JP7220761B1 - Water-based paint composition and coated article - Google Patents

Abstract

An object of the present invention is to provide a water-based coating composition capable of forming a coating film having low odor, gloss, reduced tackiness, and excellent water resistance and low-temperature film-forming properties. The acrylic resin (A) and (B) having a specific glass transition temperature are contained in a specific mass ratio, and selected from the group consisting of alkaline inorganic compounds excluding ammonia and alkaline organic compounds having a boiling point of over 260°C. A water-based coating composition comprising a selected neutralizing agent (C), wherein the acrylic resin (A) and the acrylic resin (B) are each dispersed in the form of an emulsion, containing an organic compound having a boiling point of 260°C or less. The content is 3.0% by mass or less, the ammonia concentration measured by a specific ammonia concentration measurement method is 12 ppm by volume or less, and the gloss at 60 ° of the coating film obtained from the water-based coating composition is It is a water-based coating composition characterized by being 10 or more. [Selection figure] None

Description

The present invention relates to a water-based coating composition and a coated article using the water-based coating composition, and in particular, a coating film that has low odor, has gloss, suppresses tackiness, and has excellent water resistance and low-temperature film-forming properties. It relates to formable water-based coating compositions.

In recent years, interior and exterior architectural paints, especially indoor paints, have been demanded to switch from solvent-based paints to water-based paints from the viewpoint of air pollution, odor, safety, etc. Currently, water-based emulsions are used as binders in most applications. water-based paints are the mainstream. However, a small amount of volatile organic compounds (VOC) contained in water-based paints still remains a problem of odor, and there is a strong demand for their further reduction.

Even if the amount of residual monomers is very small, water-based emulsions and paints using the same pose a problem of odors, especially those derived from acrylic monomers, and there has been a strong demand for their reduction. In addition, a small amount of an acidic group-containing polymerizable unsaturated monomer such as carboxylic acid is copolymerized in the emulsion as a component for ensuring the coating workability and stability of the paint and the adhesive strength to the object to be coated. Conventionally, various amines and volatile alkalis such as ammonia, which are not included in VOCs, have been used as neutralizing agents.

For example, it is also known to use other neutralizing agents instead of ammonia. Although the problem of odor can be solved by this method, another problem has arisen in that the water resistance is lowered. In response to such problems, in International Publication No. 2020/184722 (Patent Document 1), alkaline inorganic compounds other than ammonia or alkaline organic compounds with a boiling point of over 260 ° C. are mixed in order to avoid the use of odorous components. It is described that by using a reactive emulsifier as a part of the acrylic resin raw material in addition to using it as a blending agent, it is possible to suppress the decrease in water resistance that may occur due to the use of the neutralizer.

WO2020/184722

The inventors of the present invention have studied a coating composition suitable for forming a low-odor and glossy coating film, and found that a glossy coating film (glossy coating film) has a tacky feel (sticky feeling). It was found that water resistance may be lowered in some cases. A method using a resin with a high glass transition temperature was also considered to suppress the tackiness and improve water resistance, but in this case, it would be necessary to add a large amount of film-forming aid, and There was a problem that an odor was generated.

Accordingly, an object of the present invention is to provide a water-based coating composition that solves the above-described problems of the prior art and is capable of forming a coating film with low odor, gloss, reduced tackiness, and excellent water resistance and low-temperature film-forming properties. is to provide Another object of the present invention is to provide a coated article using such a water-based coating composition.

As a result of intensive studies to achieve the above object, the present inventors found that in order to avoid the use of odorous components in coating compositions for forming glossy coating films, alkaline inorganic compounds other than ammonia or boiling point By using an alkaline organic compound with a temperature of over 260°C as a neutralizing agent, and then using a specific amount of two types of acrylic resins with a specific glass transition temperature together, film formation can be achieved without using a film-forming aid. The present inventors have found that it is possible to form a coating film that is capable of forming a film, has a low odor, has gloss, suppresses tackiness, and is excellent in water resistance and low-temperature film-forming properties, and has completed the present invention.

Therefore, the water-based coating composition according to the present invention comprises an acrylic resin (A) having a glass transition temperature of less than 5°C, an acrylic resin (B) having a glass transition temperature of 5°C or more and 100°C or less, and an alkaline inorganic material other than ammonia. compound and a neutralizing agent (C) selected from the group consisting of alkaline organic compounds having a boiling point of over 260°C, wherein the acrylic resin (A) and the acrylic resin (B) are each dispersed in the form of an emulsion. A water-based coating composition, wherein the mass ratio (A)/(B) of the acrylic resin (A) and the acrylic resin (B) is 50/50 to 90/10, and an organic compound having a boiling point of 260 ° C. or less The content is 3.0% by mass or less, the ammonia concentration measured by the ammonia concentration measurement method described below is 12 ppm by volume or less, and the glossiness at 60 ° of the coating film obtained from the water-based coating composition is 10 or more.
<Method for measuring ammonia concentration>
A 3 L polyvinyl fluoride sampling bag is filled with 3 L of odorless air, 20 g of the coating composition is poured into the sampling bag, and the sampling bag is sealed. Then, after standing at 23° C. for 30 minutes, the ammonia concentration in the sampling bag is measured using an ammonia gas detector tube.

In a preferred embodiment of the water-based coating composition according to the present invention, the acrylic resin (B) has a glass transition temperature of 10 to 70°C.

In another preferred embodiment of the water-based coating composition according to the present invention, the glossiness at 60° of the coating film obtained from the water-based coating composition is 70-90.

Another preferred embodiment of the water-based paint composition according to the present invention further comprises a color pigment (D).

Another preferred example of the water-based coating composition according to the present invention does not contain organic compounds having a boiling point of 260° C. or less.

Also, the coated article according to the present invention is a coated article obtained by applying the water-based coating composition according to the present invention to an interior base material of a building.

According to the water-based coating composition according to the present invention, it is possible to provide a water-based coating composition capable of forming a coating film having low odor, gloss, suppressed tackiness, and excellent water resistance and low-temperature film-forming properties. . Also, according to the coated article according to the present invention, it is possible to provide a coated article using such a water-based coating composition.

The present invention will be described in detail below.

One aspect of the present invention includes an acrylic resin (A) having a glass transition temperature of less than 5 ° C., an acrylic resin (B) having a glass transition temperature of 5 ° C. or higher and 100 ° C. or lower, and an alkaline inorganic compound other than ammonia and a boiling point and a neutralizing agent (C) selected from the group consisting of organic compounds having an alkalinity above 260°C. In this specification, this coating composition is also referred to as "the water-based coating composition of the present invention" or "the coating composition of the present invention".

The coating composition of the present invention contains an acrylic resin. In the present specification, the acrylic resin is a polymer of acrylic acid esters or methacrylic acid esters, for example, one or more acrylic components selected from acrylic acid, methacrylic acid and its esters, amides and nitriles. Examples include polymers obtained by polymerizing seeds, and further include polymers obtained by polymerizing an acrylic component with a non-acrylic component such as styrene.

Examples of acrylic components include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate , n-amyl (meth)acrylate, isoamyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, methoxyethyl (meth)acrylate (Meth)acrylate monomers such as acrylate, ethoxyethyl (meth)acrylate, methoxypropyl (meth)acrylate, ethoxypropyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl acrylate, 2-aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, 3-aminopropyl (meth) acrylate, 2-butylaminoethyl (meth) ) Functional group-containing monomers such as acrylate, glycidyl (meth)acrylate, and allyl glycidyl ether. acrylic acid and methacrylic acid; amide-based monomers such as acrylic amide and methacrylic amide; γ-(meth)acryloxypropyltrimethoxysilane, γ-(meth)acryloxypropyltriethoxysilane, β-(meth) Acryloxyethyltrimethoxysilane, β-(meth)acryloxyethyltriethoxysilane, γ-(meth)acryloxypropylmethyldimethoxysilane, γ-(meth)acryloxypropylmethyldiethoxysilane, γ-(meth)acrylic alkoxysilyl group-containing monomers such as oxypropylmethyldipropoxysilane, γ-(meth)acryloxybutylphenyldimethoxysilane, γ-(meth)acryloxypropyldimethylmethoxysilane, and γ-(meth)acryloxypropyldiethylmethoxysilane; Polymers and the like are also included in acrylic components.

The ratio of the acrylic component to the total components constituting the acrylic resin is, for example, 40 to 100% by mass. The ratio of the acrylic component here refers to the entire acrylic resin contained in the coating composition, but it also applies to each of the acrylic resin (A) and the acrylic resin (B) described later.

Examples of non-acrylic components include carboxyl group-containing monomers such as fumaric acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, crotonic acid, and vinylversatic acid; styrene, methylstyrene, chlorostyrene, methoxy aromatic monomers such as styrene and vinyltoluene; olefin monomers such as ethylene and propylene; vinyl monomers such as vinyl acetate and vinyl chloride; amide monomers such as maleamide; Alkoxysilyl group-containing monomers such as vinylmethyldimethoxysilane and vinylmethyldiethoxysilane; dialkyl fumarate, allyl alcohol, vinylpyridine, butadiene and the like.

In the coating composition of the present invention, the amount of the acrylic resin in the nonvolatile matter is preferably 15% by mass or more and less than 100% by mass, more preferably 15 to 99% by mass, and 15 to 80% by mass. It is even more preferable to have Acrylic resins may be used singly or in combination of two or more.

The content of nonvolatile matter in the coating composition of the present invention is preferably 30 to 80% by mass. In the present specification, the non-volatile content refers to components excluding volatile components such as solvents, and is a component that will eventually form a coating film. The components remaining after drying for 60 minutes are treated as non-volatiles.

The coating composition of the present invention contains two acrylic resins with different glass transition temperatures. One is an acrylic resin with a glass transition temperature of less than 5°C, and the other is an acrylic resin with a glass transition temperature of 5°C or higher and 100°C or lower. In this specification, an acrylic resin having a glass transition temperature of less than 5°C is also referred to as "acrylic resin (A)", and an acrylic resin having a glass transition temperature of 5°C or higher and 100°C or lower is also referred to as "acrylic resin (B)".

The acrylic resin (A) is an acrylic resin having a glass transition temperature of less than 5°C and can improve film formability. Therefore, even when the acrylic resin (B) is used, by using the acrylic resin (A) in combination, it is possible to ensure low-temperature film-forming properties without using a film-forming aid. The glass transition temperature of the acrylic resin (A) is preferably 0°C or lower, more preferably -50 to 0°C, and even more preferably -10 to 0°C.

The acrylic resin (B) is an acrylic resin having a glass transition temperature of 5° C. or higher and 100° C. or lower, and can suppress the tackiness (stickiness) of the coating film and improve the water resistance of the coating film. For example, when forming a glossy coating film, particularly a glossy coating film, tackiness (stickiness) and water resistance may be a problem, so it is effective to use an acrylic resin (B). On the other hand, when the acrylic resin (B) is used, the use of a film-forming aid is usually required, so there is the problem of odor. However, according to the present invention, by using an acrylic resin having a glass transition temperature of less than 5° C. together with the acrylic resin (B) having a glass transition temperature of 5° C. or more and 100° C. or less, it is possible to form a good film. The use of deposition aids can be avoided. The glass transition temperature of the acrylic resin (B) is preferably 10 to 70°C, more preferably 20 to 60°C.

In the coating composition of the present invention, the mass ratio (A)/(B) of the acrylic resin (A) and the acrylic resin (B), that is, the mass ratio of the acrylic resin (A)/acrylic resin (B) is 50/50. ~90/10 is preferred, and 60/40 to 80/20 is more preferred. By using the acrylic resin (A) and the acrylic resin (B) in such a mass ratio, it is possible to suppress the tackiness without using a film-forming aid, and to form a coating film that is excellent in water resistance and low-temperature film-forming properties. A formable coating composition can be provided. In addition, when replacing with acrylic resin (B) and using the acrylic resin whose glass transition temperature exceeds 100 degreeC, there exists a possibility that film-forming defect may arise.

As used herein, the glass transition temperature (Tg) of an acrylic resin is calculated using the following FOX formula.
1/Tg=W1/Tg1+W2/Tg2+...+Wi/Tgi+...+Wn/Tgn
In the FOX formula, Tg is the glass transition temperature (K) of a polymer consisting of n types of monomers, and Tg(1,2,i,n) is the glass transition temperature (K) of a homopolymer of each monomer. , W(1,2,i,n) are the mass fractions of each monomer, and W1+W2+...+Wi+...+Wn=1.

The glass transition temperature of homopolymers is common technical knowledge, but when using a monomer whose glass transition temperature is unknown, the glass transition temperature of the monomer can be determined by differential scanning calorimetry (DSC) or differential calorimetry (DTA). , thermomechanical analysis (TMA), or the like.

In the coating composition of the present invention, the acrylic resin may be an acrylic resin containing structural units derived from a reactive emulsifier. By containing the reactive emulsifier as a structural unit, the elution of the emulsifier from the coating film obtained from the coating composition can be suppressed, and the water resistance of the coating film can be improved. Furthermore, by including a reactive emulsifier as a structural unit, low-temperature stability can also be improved. For this reason, even if the paint is repeatedly frozen and thawed as specified in JIS K5663:2008 "7.6 Low temperature stability test", the paint after thawing retains its original properties. It is possible to return to Emulsifiers are generally used to facilitate the formation of emulsions or to aid in the stability of emulsions. Since it is sometimes incorporated as a constituent unit of the polymer as a monomer, it is also preferable from the viewpoint of suppressing bleeding out of the emulsifier.

Reactive emulsifiers include, for example, anionic or nonionic reactive emulsifiers.

From the viewpoint of emulsion stability, the reactive emulsifier preferably has a polyalkylene glycol chain. Examples of polyalkylene glycol chains include polyethylene glycol chains and polypropylene glycol chains. Further, the reactive emulsifier preferably has a molecular weight within the range of 200 to 3,500 from the viewpoint of water resistance and emulsion stability.

Examples of reactive emulsifiers include emulsifiers having a polymerizable unsaturated bond such as a vinyl group in the molecule. Such a reactive emulsifier not only has an emulsifying function, but is also a polymerizable monomer having a polymerizable unsaturated bond such as a vinyl group and a hydrophilic group in the molecule. Whereas ordinary emulsifiers only adsorb to the surfaces of produced particles, reactive emulsifiers may be incorporated into the polymer as one component of the polymer during the polymerization process of the polymer, although not all of them. After forming the coating film, the emulsifier is not or hardly released from the polymer due to external factors such as water vapor.

Examples of anionic reactive emulsifiers include alkyl ether type (commercially available products include Aqualon KH-05 and KH-10 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Adekaria Soap SR-10 manufactured by ADEKA Co., Ltd., SR-1025, SR-20, R-3025, Latemul PD-104 manufactured by Kao Corporation), sulfosuccinate ester type (commercially available products include, for example, Latemul S-120, S-120A manufactured by Kao Corporation, S-180P, S-180A, eleminol JS-20 manufactured by Sanyo Kasei Co., Ltd.), alkylphenyl ether type or alkylphenyl ester type (commercially available products include, for example, Aqualon HS-10 manufactured by Daiichi Kogyo Seiyaku Co., Ltd. , HS-1025, AR-10, AR-1025, AR-20, AR-2020, BC-10, BC-1025, BC-20, BC-2020, Adekaria Soap SE-10N, SE manufactured by ADEKA Co., Ltd. -1025A, etc.), (meth) acrylate sulfate ester type (commercially available products include, for example, Antox MS-60, SAD, MS-2N manufactured by Nippon Nyukazai Co., Ltd., Eleminol RS-3000 manufactured by Sanyo Chemical Industries, Ltd., etc. ), phosphate ester type (commercially available products include, for example, H-3330PL manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., and Adekaria Soap PP-70 manufactured by ADEKA Co., Ltd.).

Examples of nonionic reactive emulsifiers include alkyl ether type (commercially available products include Aqualon KN-10, KN-20, KN-30, KN-5065 manufactured by Daiichi Kogyo Seiyaku Co., Ltd., manufactured by ADEKA Co., Ltd. Adekaria Soap ER-10, ER-20, ER-30, ER-40, Kao Corporation Latemul PD-420, PD-430, PD-450, etc.), alkylphenyl ether type or alkylphenyl ester type ( Commercial products include, for example, Aqualon RN-10, RN-20, RN-30, RN-50, AN-10, AN-20, AN-30, AN-5065 manufactured by Daiichi Kogyo Seiyaku Co., Ltd. Adekaria soap NE-10, NE-20, NE-30, etc. manufactured by ADEKA), (meth) acrylate ester type (commercially available products include, for example, MA-50A, MA-100A, MPG- 130MA, NOF CORPORATION BLEMMER PE-90, PP-1000, 50PEP-300, AE-200, AP-400, etc.).

In the coating composition of the present invention, one or both of the acrylic resin (A) and the acrylic resin (B) may be an acrylic resin containing a structural unit derived from a reactive emulsifier.

The ratio of the reactive emulsifier to the total components constituting the acrylic resin is preferably, for example, in the range of 0.5 to 10% by mass. Reactive emulsifiers may be used singly or in combination of two or more.

In the coating composition of the present invention, the acrylic resin is preferably an acrylic resin containing structural units derived from an acidic group-containing monomer. Adhesion of the coating film can be improved by using the acidic group-containing monomer. Examples of acid groups include carboxylic acid groups and sulfonic acid groups. Examples of acidic group-containing monomers include acrylic acid, ethyl acrylic acid, propyl acrylic acid, isopropyl acrylic acid, methacrylic acid, fumaric acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, crotonic acid, and vinyl versatic. Examples thereof include carboxyl group-containing monomers such as acids and sulfonic acid group-containing monomers such as t-butylacrylamide sulfonic acid. In the coating composition of the present invention, one or both of the acrylic resin (A) and the acrylic resin (B) may be an acrylic resin containing a structural unit derived from an acidic group-containing monomer.

The ratio of the acidic group-containing monomer to the total components constituting the acrylic resin is preferably, for example, in the range of 0.1 to 5% by mass. Although the ratio of the acidic group-containing monomer here is for the entire acrylic resin contained in the coating composition, it also applies to each of the acrylic resin (A) and the acrylic resin (B). The acidic group-containing monomers may be used singly or in combination of two or more.

In the coating composition of the present invention, the acrylic resin is preferably dispersed in the coating composition in the form of an emulsion, and the acrylic resin (A) and the acrylic resin (B) are each dispersed in the form of an emulsion. preferably. Therefore, it is preferable to use an acrylic resin emulsion when preparing the coating composition of the present invention. An acrylic resin emulsion means an emulsion in which an acrylic resin is stably dispersed in water, and additives such as emulsifiers are included as necessary. A paint in which a resin is dispersed in the form of an emulsion is also called an emulsion paint.

In the coating composition of the present invention, the acrylic resin emulsion can be prepared, for example, by using water as a medium and performing emulsion polymerization in water. More preferably, an acrylic resin emulsion having a uniform structure obtained by emulsion polymerization, an acrylic resin emulsion having a heterogeneous structure obtained by a multistage emulsion polymerization method, and the like may be used together. Alternatively, an acrylic resin emulsion can be prepared as follows. For example, it may be prepared by emulsifying the acrylic resin in water while applying a compulsory shearing force using a high-speed stirrer or the like. An acrylic resin emulsion can be prepared by subjecting an acrylic resin polymerized in an organic solvent medium to phase conversion to water, and if necessary, the organic solvent contained in the acrylic resin emulsion can be removed by distillation or the like. You may

Furthermore, in order to improve the function of the resulting coating film, it is possible to introduce a crosslinked structure into the acrylic resin. In general, crosslinked structures are broadly classified into two types: "internal crosslinked structure of particles" and "crosslinked structure between particles".

By introducing this "intra-particle cross-linking structure" and "inter-particle cross-linking structure" into the acrylic resin, the coating film performance such as toughness, blocking resistance, non-adhesiveness, and suppression of tackiness when made into a coating film can be improved. can be greatly improved.

In order to obtain intra-particle cross-linked structures and inter-particle cross-linked structures, for example, the following method may be used.

Intra-particle cross-linking: A monomer having two or more polymerizable unsaturated double bonds in the molecule is used.
A method using divinylbenzene, ethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, allyl(meth)acrylate, etc.; using monomers having functional groups that react with each other at the emulsion polymerization reaction temperature. method, for example, a method using a monomer having a combination of functional groups such as a carboxyl group and a glycidyl group or a hydroxyl group and an isocyanate group; (meth)acryloxypropyltrimethoxysilane, (meth)acryloxypropylmethyldimethoxysilane, etc. Examples include a method using a hydrolyzable silyl group-containing monomer that undergoes a decomposition-condensation reaction.

Cross-linking between particles: The most representative method is a method of copolymerizing a monomer having a carbonyl group and then mixing a compound (curing agent) having two or more hydrazide groups in the molecule.
Examples of carbonyl group-containing monomers include acrolein, diacetone (meth)acrylamide, formylstyrene, (meth)acryloxyalkylpropanal, diacetone (meth)acrylate, acetonyl (meth)acrylate, acetoacetoxyethyl (meth)acrylate, 2 -hydroxypropyl (meth)acrylate-acetylacetate, butanediol-1,4-acrylate-acetylacrylate, vinyl ethyl ketone, vinyl isobutyl ketone and the like. Acrolein, diacetone acrylamide and vinyl ethyl ketone are particularly preferred. On the other hand, examples of the compound having two or more hydrazide groups in the molecule to be paired with the carbonyl group include carbohydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide, isophthalic acid dihydrazide, citric acid trihydrazide, 1,2,4-benzenetrihydrazide, thiocarbodihydrazide and the like. Among these, carbohydrazide, adipic acid dihydrazide and succinic acid dihydrazide are preferable from the viewpoint of the balance of dispersibility in emulsion and water resistance.

For emulsion polymerization, a surfactant generally used in emulsion polymerization can be used as an emulsifier. For example, fatty acid salts such as sodium lauryl sulfate, higher alcohol sulfate salts, alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate, polyoxyethylene alkyl ether sulfates, ammonium polyoxynonylphenyl ether sulfonate, polyoxyethylene styrene Anions such as so-called reactive emulsifiers having a sulfonic acid group or a sulfate ester group and a polymerizable carbon-carbon unsaturated double bond in the molecule surfactant; polyoxyethylene alkyl ether, polyoxyethylene nonylphenyl ether, sorbitan fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene-polyoxypropylene block copolymer, or carbon-carbon polymerizable with the aforementioned skeleton Examples include nonionic surfactants such as reactive nonionic surfactants having an unsaturated double bond in the molecule; cationic surfactants such as alkylamine salts and quaternary ammonium salts. Among these, the anionic surfactant which is an ammonium salt is preferable because of its high water resistance effect.

In the present invention, a reactive emulsifier and a non-reactive emulsifier may be used in combination to prepare the acrylic resin emulsion.

In the coating composition of the present invention, the acrylic resin emulsion preferably has a pH of 7-10. For example, a neutralizing agent can be used to adjust the pH of the acrylic resin emulsion within the range specified above. If the pH of the acrylic resin emulsion is less than 7, various stability such as storage stability and mechanical stability of the paint may decrease. The neutralizing agent that can be used here is preferably a neutralizing agent selected from the group consisting of alkaline inorganic compounds other than ammonia and alkaline organic compounds having a boiling point of over 260° C., as described later.

In the acrylic resin emulsion, the acrylic component and the non-acrylic component used as raw materials for the acrylic resin may remain without being polymerized. In addition, raw materials for the acrylic resin emulsion may contain ammonia and VOC compounds. It is preferable to remove the unreacted monomers, ammonia, and VOC compounds remaining in this way from the viewpoint of suppressing the generation of odors. Therefore, it is preferable to remove them under reduced pressure during or after preparation of the acrylic resin emulsion.

In the coating composition of the present invention, the acrylic resin (A) and the acrylic resin (B) each independently have a volume average particle diameter of preferably 30 to 300 nm, more preferably 60 to 300 nm. . By adjusting the volume-average particle size of the acrylic resin dispersed in the coating composition of the present invention to 30 to 300 nm, low-temperature film-forming properties and low-temperature stability can be improved.

As used herein, the volume average particle size refers to the 50% particle size (D ₅₀ ) of the volume-based particle size distribution, and is a particle size measured using a particle size distribution analyzer (e.g., a laser diffraction/scattering particle size distribution analyzer). It can be obtained from the distribution. The particle diameter is represented by a sphere-equivalent diameter measured by a laser diffraction/scattering method.

The coating composition of the present invention contains a neutralizing agent selected from the group consisting of alkaline inorganic compounds excluding ammonia and alkaline organic compounds having a boiling point of over 260°C. This neutralizing agent is also referred to herein as "neutralizing agent (C)". Except for ammonia, alkaline inorganic compounds that can be used as neutralizers are odorless or have a low odor, and are therefore suitable from the viewpoint of suppressing the generation of odor from the coating composition. In addition, if the alkaline organic compound that can be used as a neutralizing agent has a boiling point of more than 260° C., it usually does not evaporate during coating and remains in the coating film, so the odor of the coating composition is reduced. It is suitable from the viewpoint of suppressing the occurrence. As used herein, boiling point is the boiling point at 1 atmosphere.

Examples of the alkaline inorganic compound that can be used as a neutralizing agent in the coating composition of the present invention include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkali metal hydrogen carbonates such as sodium hydrogen carbonate, and carbonates. Examples thereof include alkali metal carbonates such as sodium, and among these, sodium hydroxide is preferred.

Examples of the alkaline organic compound that can be used as the neutralizing agent in the coating composition of the present invention include amine compounds, specifically amine compounds capable of forming an ion pair with an acid group. Here, examples of the amine compound having a boiling point of over 260° C. include triethanolamine, diethanolamine, N-butyldiethanolamine, and the like.

In the coating composition of the present invention, the content of the neutralizing agent is not particularly limited, but the neutralizing agent can be used so that the pH of the above acrylic resin emulsion or coating composition is 7 to 10. preferable. Part or all of the neutralizing agent contained in the coating composition of the present invention is preferably contained in the acrylic resin emulsion. Neutralizing agents may be used singly or in combination of two or more.

In the coating composition of the present invention, the total content of the acrylic resin and the neutralizing agent in the nonvolatile matter is preferably 15 to 100% by mass.

The coating composition of the present invention may contain color pigments. Coloring pigments are also referred to herein as “coloring pigments (D)”. The coloring pigment is not particularly limited, and pigments commonly used in the paint industry can be used. Specific examples include inorganic pigments such as titanium dioxide, iron oxide and carbon black, and organic pigments such as phthalocyanine pigments and azo pigments. In the coating composition of the present invention, the amount of the color pigment in the non-volatile matter is preferably 1-80% by mass, more preferably 20-75% by mass. Coloring pigments may be used singly or in combination of two or more.

The coating composition of the present invention may contain an extender pigment. Examples of extender pigments include silica, talc, mica, calcium carbonate, barium sulfate, clay and the like. Kaolin, silica and calcium carbonate are preferred extender pigments due to their low odor. In the coating composition of the present invention, the amount of the extender pigment in the nonvolatile matter is preferably 1 to 65% by mass. Extender pigments may be used singly or in combination of two or more. The extender pigment may be used from the viewpoint of adjusting the glossiness of the coating film.

The coating composition of the present invention may contain other pigments classified into metallic pigments, luster pigments, scaly pigments, and the like. For example, aluminum powder pigment, nickel powder pigment, gold powder, silver powder, bronze powder, copper powder, stainless steel powder pigment, mica (mica) pigment, graphite pigment, glass flake pigment, metal coated glass powder, metal coated mica powder, Examples include metal-coated plastic powder and scaly iron oxide pigments.

In one embodiment of the present invention, the pigment can be appropriately selected according to the coloration and luster of the coating film, coating workability, strength of the coating film, physical properties, and the like. In the coating composition of the present invention, the amount of pigment in the nonvolatile matter is preferably 0 to 80% by mass. When the paint composition does not contain pigment, the paint composition of the present invention can be used as a clear paint.

The coating composition of the present invention may contain an antifoaming agent. Commercially available antifoaming agents can be used as appropriate, but it is preferable to use those with little odor. Antifoaming agents are generally classified into mineral oil-based, silicone-based, polyether-based, etc., depending on the carrier oil, and usually contain a nucleating agent such as hydrophobic silica, wax, amide, metal soap, etc. as a constituent component in addition to the carrier. . The amount of antifoaming agent in the coating composition of the present invention is preferably 0.01 to 5% by weight. Antifoaming agents may be used singly or in combination of two or more.

The coating composition of the present invention may contain a viscosity modifier. The viscosity modifier is preferably a polyacrylic acid-based viscosity modifier or a polyurethane-based viscosity modifier. The polyacrylic acid-based viscosity modifier is, for example, an amine salt, an amide salt or a sodium salt of a polymer obtained by polymerizing one or more acrylic components selected from acrylic acid or its esters, amides and nitriles. and has multiple carboxyl groups or salts thereof in the molecule. Commercially available polyacrylic acid-based viscosity modifiers include, for example, Thikzol K-130B (Kyoeisha Co., Ltd., aqueous dispersion of polyacrylic acid aliphatic polyamide). Polyurethane-based viscosity modifiers include, for example, compounds having urethane sites and hydrophilic sites formed by the reaction of hydroxyl groups and isocyanate groups in the molecule, and urea sites and hydrophilic sites formed by the reaction of amino groups and isocyanate groups. A compound having a site in the molecule, or a compound having a urethane site, a urea site and a hydrophilic site in the molecule can be mentioned. Examples of commercially available polyurethane-based viscosity modifiers include BYK-7420ES (BYK, ureaurethane solution).

The amount of viscosity modifier in the coating composition of the present invention is, for example, 0 to 5% by weight, preferably 0.15 to 3% by weight. A viscosity modifier may be used individually by 1 type, and may be used in combination of 2 or more types.

The coating composition of the present invention is a water-based coating composition. As used herein, a water-based coating composition is a coating composition containing water as a main solvent. Here, the water used in the coating composition is not particularly limited, and preferably includes pure water such as ion-exchanged water and distilled water, but ground water and tap water may also be used. Moreover, when the coating composition is to be stored for a long period of time, water sterilized by ultraviolet irradiation or the like may be used in order to prevent the generation of mold or bacteria. The amount of water in the coating composition of the present invention is preferably 20-70 mass %. Also, the coating composition of the present invention can be completely water-based, and the ratio of water in the solvent used is preferably 85% by mass or more, most preferably 100% by mass.

The water-based coating composition of the present invention contains, as other components, other resins, surface conditioners, wetting agents, dispersants, emulsifiers, thickeners, anti-settling agents, anti-skinning agents, anti-sagging agents, and color separation agents. Inhibitors, matting agents, leveling agents, desiccants, plasticizers, film-forming aids, antifungal agents, antibacterial agents, antiviral agents, preservatives, insecticides, light stabilizers, ultraviolet absorbers, antistatic agents and a conductivity-imparting agent, etc., can be appropriately blended depending on the purpose. Commercially available products can be suitably used as these components.

An organic solvent (for example, an organic solvent contained in a film-forming aid or an additive) may be used in the water-based coating composition of the present invention. The amount is preferably 15% by weight or less, most preferably 0% by weight. Also, in preferred embodiments of the present invention, it is preferred not to use a deposition aid.

From the viewpoint of suppressing the generation of odor, the water-based coating composition of the present invention preferably contains 3.0% by mass or less of an organic compound having a boiling point of 260°C or less, and does not contain an organic compound having a boiling point of 260°C or less. is particularly preferred. Examples of organic compounds having a boiling point of 260° C. or lower that are used in the coating composition include organic solvents.

The coating composition of the present invention can be prepared by mixing various components appropriately selected according to need. The coating composition of the present invention may be of a one-pack type or a two-pack type, but is preferably used as a one-pack type, and is preferably a water-based coating composition that dries at room temperature. Here, "normal temperature" means 5 to 35 ° C., and according to the coating composition of the present invention, it is possible to dry within 16 hours at 23 ° C. and within 24 hours at 5 ° C. is.

The coating composition (emulsion coating) of the present invention and the acrylic resin emulsion that can be blended in the coating composition preferably have a minimum film-forming temperature of 5° C. or lower, more preferably 0° C. or lower. In this specification, the minimum film-forming temperature is measured according to JIS K6828-2:2003.

The coating composition of the present invention has a viscosity of 0.1 to 10,000 Pa s at a shear rate of 0.1 s ^-1 and a viscosity of 0.05 to 10 Pa s at a shear rate of 1,000 s ^-1 . is preferred. In this specification, the viscosity is measured after adjusting the liquid temperature to 23° C. using a rheometer (such as rheometer ARES manufactured by TA Instruments).

The coating composition of the present invention preferably has an ammonia concentration of 12 ppm by volume or less as measured by the ammonia concentration measuring method described below.
<Method for measuring ammonia concentration>
A 3 L polyvinyl fluoride sampling bag is filled with 3 L of odorless air, 20 g of the coating composition is poured into the sampling bag, and the sampling bag is sealed. Then, after standing at 23° C. for 30 minutes, the ammonia concentration in the sampling bag is measured using an ammonia gas detector tube.
In this specification, odorless air can be general odorless air used for odor analysis, and usually air from which impurities have been removed with activated carbon is used as odorless air.

In addition, the coating composition of the present invention preferably has a concentration of unreacted monomers of 100 ppm by volume or less as measured by the following measuring method.
<Method for measuring concentration of unreacted monomer>
A 3 L polyvinyl fluoride sampling bag is filled with 3 L of odorless air, 20 g of the coating composition is injected into the sampling bag, the sampling bag is sealed, and then left at 23 ° C. for 30 minutes. Measure the concentration of unreacted monomer in the sampling bag using a detector tube capable of detecting the monomers that react.
In this specification, odorless air can be general odorless air used for odor analysis, and usually air from which impurities have been removed with activated carbon is used as odorless air.

The coating composition of the present invention preferably has a glossiness of 10 or more at 60° of the coating film obtained from the coating composition. For example, when forming a glossy coating film, the coating composition The glossiness at 60° of the resulting coating film is preferably 70-90.

In this specification, the glossiness at 60° is defined by JIS K5600-4-7 (ISO 2813: 1994) according to the specular glossiness (D60) at 60°, for example, gloss meter VG manufactured by Nippon Denshoku Co., Ltd. It can be measured using -2000.

The coating means of the coating composition of the present invention is not particularly limited, and known coating means such as brush coating, roller coating, trowel coating, spatula coating, flow coater coating, spray coating (e.g. air spray coating, airless spray coating) ) etc. can be used.

The method for drying the coating composition of the present invention is not particularly limited, and may be natural drying at ambient temperature or forced drying using a dryer or the like.

Another aspect of the present invention is a coated article obtained by applying the water-based coating composition of the present invention onto a substrate. This coated article is also referred to herein as the "coated article of the present invention". The coated article of the present invention can also be referred to as a coated article having a coating film obtained from the aqueous coating composition of the present invention on a substrate.

The film thickness of the coating film obtained from the water-based coating composition of the present invention is, for example, 20 to 80 μm.

In the coated article of the present invention, examples of substrates include epoxy resins, ABS resins, polycarbonates, polyvinyl chloride, polystyrene, acrylic resins such as polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polyolefins such as polypropylene. (PP) and other plastic substrates, steel, galvanized steel, tinned steel, stainless steel, magnesium alloys, aluminum, aluminum alloys, titanium, titanium alloys and other metal substrates, cement, mortar, concrete, slate, gypsum, Inorganic base materials other than metals such as calcium silicate, glass, ceramics, calcium carbonate, marble and artificial marble, woody base materials such as wood, and composite base materials such as a combination of two or more of these base materials. mentioned. Examples of composite base materials include composite base materials such as wood fiber reinforced cement boards, fiber reinforced cement boards, fiber reinforced cement/calcium silicate boards, metal base materials subjected to various surface treatments such as oxidation treatment, and the like. A plastic substrate whose surface is coated with an inorganic substance (for example, a plastic substrate coated with a vitreous substance) and the like can be mentioned.

The base material has various shapes, such as a plate-like base material. The surface of the substrate may be smooth or may have unevenness.

Specific examples of the substrate preferably include structures such as buildings and constructions, vehicles (automobiles, etc.), furniture, fittings, electronic devices (home appliances, etc.), and parts thereof. Here, the coated article of the present invention is suitable as a base material for the interior and exterior (for interior and/or exterior) of structures. In the present invention, a building means a structure built for the purpose of human residence or stay, for example, a house (especially a detached house or collective housing), a building, a factory, etc. Structures constructed for purposes other than human habitation or residence, such as bridges, tanks, plant piping, chimneys, and the like. Examples of structural members include roofs and walls (inner walls, outer walls, particularly curtain walls).

The coated article of the present invention is preferably a building material, particularly a building board. Specific examples of building base materials include wooden building materials such as veneers, plywoods, particle boards, and medium density fiberboards (MDF); ceramic siding boards, flexible boards, calcium silicate boards, gypsum slag barlite boards, and wood chips. Ceramic building materials such as cement board, asbestos cement board, pulp cement board, precast concrete board, lightweight aerated concrete (ALC) board or ALC panel, gypsum board; various building materials such as metal siding board, metal building materials such as aluminum, iron, stainless steel, etc. (especially building boards) are preferred. Specific examples of the substrate include plastic substrates such as vinyl chloride sheets, tarpaulins, plastic cardboard (plastic cardboard), acrylic plates, tiles, and glass plates.

The surface of the base material may be subjected to pretreatment such as degreasing treatment, chemical conversion treatment, polishing, sealer, primer coating, or the like. For example, if the base material is a base material (especially a porous base material) that may absorb excessive paint such as ceramic building materials, the surface of the base material is coated with a sealer to form a sealer layer on the base material. may have been. Moreover, when the base material is a metal building material or the like, the surface of the base material may be coated with a primer to form a primer layer on the base material.

In a preferred embodiment of the present invention, the coating composition of the present invention can be applied to a building interior substrate.

The coated article of the present invention is not limited to the embodiment in which the coating composition of the present invention is directly applied to the substrate, but a coating layer is formed on the substrate, and the coating layer of the present invention is formed on the coating layer. A mode of applying the composition is also included.

The coating film layer that can be formed between the coating film obtained from the aqueous coating composition of the present invention and the substrate may be a single layer or multiple layers, and is coated for various purposes. For example, when a design is applied to a substrate, a design layer can be coated, and when protecting the surface of a substrate, a protective layer can be coated. A coating layer can also be applied for the purpose of improving the adhesion between the coating obtained from the article and the substrate. The coating layer may be composed of a plurality of coating layers for different purposes, and for example, a design layer and a protective layer may be laminated.

Hereinafter, the coating film layer that can be formed between the coating film obtained from the water-based coating composition of the present invention and the substrate is also simply referred to as "coating layer". The film thickness of the coating layer is, for example, 20 to 80 μm.

The coating layer preferably contains a resin, for example, acrylic resin, silicone resin, acrylic silicone resin, styrene-acrylic copolymer resin, polyester resin, fluorine resin, rosin resin, petroleum resin, coumarone resin, phenol resin, urethane resin. , melamine resins, urea resins, epoxy resins, cellulose resins, xylene resins, alkyd resins, aliphatic hydrocarbon resins, butyral resins, maleic acid resins, fumaric acid resins, vinyl resins, amine resins, ketimine resins, and these resins. Examples include modified resins (modified resins). The resin may be used singly or in combination of two or more.

The coating film layer preferably contains the same resin as the coating film obtained from the aqueous coating composition of the present invention. This can improve the adhesion between the coating film layer and the coating film obtained from the water-based coating composition of the present invention.

The coating layer preferably contains a pigment. As the pigment, for example, pigments commonly used in the paint industry, such as coloring pigments, extender pigments, rust-preventing pigments, and luster pigments, can be used. A pigment may be used individually by 1 type, and may be used in combination of 2 or more types.

Other components of the coating layer include dispersants, surface modifiers, antioxidants, plasticizers, rust inhibitors, solvents, antibacterial agents, antiviral agents, viscosity modifiers, fillers, antifoaming agents, and charge control agents. Additives such as agents, stress relieving agents, penetrating agents, light guiding materials, glittering materials, magnetic materials, phosphors, ultraviolet absorbers, radical scavengers, etc. may be included as necessary.

The coating film layer is formed from various coatings such as, for example, an organic solvent-based coating using an organic solvent as the main solvent, a water-based coating using water as the main solvent, a photocurable coating using a photopolymerizable compound, and a powder coating. be able to. In a preferred embodiment of the present invention, the coating layer can be a coating layer formed from a low-odor water-based paint, and an example of a low-odor water-based paint is an organic A solvent-free water-dispersible resin-based paint and a water-dispersible resin-based paint having a residual monomer content of less than 100 ppm by weight can be used. In a more preferred embodiment, it can be a coating film layer formed from a water-based coating composition described in International Publication No. 2020/184722.

Specifically, the coating composition for forming the coating film layer is selected from the group consisting of an acrylic resin containing a structural unit derived from a reactive emulsifier, an alkaline inorganic compound excluding ammonia, and an alkaline organic compound having a boiling point of over 260 ° C. It is more preferable that the water-based coating composition contains a selected neutralizing agent and the acrylic resin is dispersed in the water-based coating composition in the form of an emulsion. Here, "reactive emulsifier", "acrylic resin", "alkaline inorganic compounds other than ammonia", "alkaline organic compounds with a boiling point of over 260 ° C.", "aqueous coating composition", etc. The description of the "reactive emulsifier", "acrylic resin", "alkaline inorganic compounds other than ammonia", "alkaline organic compounds having a boiling point of over 260°C", "aqueous coating composition", etc. in the coating composition of the invention is the same. applies to

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

<Synthesis example A1 of acrylic resin (A) emulsion>
In a five-necked flask equipped with a stirrer, a reflux condenser, a thermometer, a dropping device, and a nitrogen inlet tube, 44 parts by mass of ion-exchanged water and 1.0 part by mass of a reactive anion emulsifier KH10 (Daiichi Kogyo Seiyaku), non- 2.0 parts by mass of reactive nonionic emulsifier ET170 (Daiichi Kogyo Seiyaku Co., Ltd.) was charged, and the temperature was raised to 80 ° C. while replacing the inside of the reaction vessel with nitrogen. 39.0 parts by mass of methyl methacrylate, 56.0 parts by mass of butyl acrylate, 3.0 parts by mass of styrene, 2.0 parts by mass of acrylic acid, 49 parts by mass of ion-exchanged water, and non-reactive A mixture of 3.0 parts by mass of an anionic emulsifier NF08 (Daiichi Kogyo Seiyaku Co., Ltd.) was continuously added dropwise over 4 hours. Then, after aging at 80° C. for 2 hours while stirring, after cooling to room temperature, an aqueous sodium hydroxide solution was adjusted to pH 9.0 to obtain an acrylic resin in the form of an emulsion. Table 1 shows the glass transition temperature (Tg, °C) of the acrylic resin obtained in Synthesis Example A1. The glass transition temperature was obtained from the FOX formula.

<Synthesis example B1 of acrylic resin (B) emulsion>
40 parts by mass of ion-exchanged water and 1.0 part by mass of reactive anion emulsifier KH10 (Daiichi Kogyo Seiyaku Co., Ltd.) were added to a five-necked flask equipped with a stirrer, reflux condenser, thermometer, dropping device, and nitrogen inlet tube. While replacing the inside of the container with nitrogen, the temperature was raised to 80° C., 1.0 parts by mass of potassium persulfate was added, and then "60.5 parts by mass of methyl methacrylate, 31 parts by mass of butyl acrylate" which had been stirred and mixed in a separate container in advance. .0 parts by mass, 5.0 parts by mass of styrene, 2.5 parts by mass of acrylic acid, 1.0 parts by mass of diacetone acrylamide, 53 parts by mass of ion-exchanged water, and non-reactive anionic emulsifier NF08 (Daiichi Kogyo Seiyaku) 5 .0 parts by mass” of the mixture was continuously added dropwise over 3.5 hours. Then, after aging at 80° C. for 2 hours while stirring, after cooling to room temperature, an aqueous sodium hydroxide solution was adjusted to pH 9.0 to obtain an acrylic resin in the form of an emulsion. Table 2 shows the glass transition temperature (Tg, °C) of the acrylic resin obtained in Synthesis Example B1. The glass transition temperature was obtained from the FOX formula.

<Synthesis Example A2 to Synthesis Example A9>
The acrylic resins of Synthesis Examples A2 to A9 were prepared in the form of emulsions under the same conditions as in Synthesis Example A1, except that the monomer formulation of the acrylic resin of Synthesis Example A1 was changed to that shown in Table 1. Table 1 shows the content (parts by mass) and the glass transition temperature (Tg, °C) of each acrylic resin.

<Synthesis Example B2 to Synthesis Example B14>
The acrylic resins of Synthesis Examples B2 to B14 were prepared in the form of emulsions under the same conditions as in Synthesis Example B1, except that the monomer formulation of the acrylic resin of Synthesis Example B1 was changed to that shown in Table 2. Further, in Synthesis Examples B7 to B9, B13 and B14, the sodium hydroxide used as the neutralizing agent in Synthesis Example B1 was changed to the neutralizing agent shown in Table 2. Table 2 shows the content (parts by mass) and glass transition temperature (Tg, °C) of each acrylic resin.

<Example 1>
10.0 parts by mass of ion-exchanged water was put into a mixer, and 0.5 parts by mass of a dispersant, 0.1 part by mass of an antifoaming agent, and a pigment component (20.0 parts by mass of titanium oxide) were added thereto under a stirring environment. Gradually added and after complete addition mixed until particle size was less than 10 μm. Next, in a mixer, 46.2 parts by mass of the resin emulsion containing the acrylic resin of Synthesis Example A1 (solid content concentration 50% by mass, solvent: water), the resin emulsion containing the acrylic resin of Synthesis Example B1 (solid content concentration 42% by mass) , solvent: water) 23.6 parts by mass, 2.0 parts by mass of a viscosity modifier, 0.3 parts by mass of an antifoaming agent, and 0.05 parts by mass of a curing agent were gradually added under a stirring environment and thoroughly mixed. After that, a water-based coating composition of Example 1 was obtained.

<Examples 2 to 22, Comparative Examples 1 to 9>
Water-based paint compositions of Examples 2 to 22 and Comparative Examples 1 to 9 were obtained in the same manner as in Example 1, except that the formulations were changed to those shown in Tables 3 to 5.

The components shown in Tables 3 to 5 are as follows.
(Note 1) Dispersant (manufactured by BYK-Chemie: BYK-190)
(Note 2) Antifoaming agent (BYK-Chemie: BYK-038)
(Note 3) Viscosity modifier (Dow Chemical Company: PRIMAL RM-2020NPR)
(Note 4) Titanium oxide (manufactured by Tayca: JR-806)
(Note 5) Calcium carbonate (manufactured by Takehara Chemical Industry Co., Ltd.: Sunlight SL-100)
(Note 6) Silica (manufactured by EP Minerals: Celatom MW-25)
(Note 7) Film formation aid A (2,2,4-trimethyl-1,3-pentanediol diisobutyrate (TXIB), boiling point: 281.5°C)
(Note 8) Film formation aid B (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (Texanol), boiling point: 253°C)
(Note 9) Curing agent (dihydrazide adipic acid)

The obtained coating compositions were evaluated as follows. The results are shown in Tables 3-5.

<Odor (ammonia concentration)>
A 3 L polyvinyl fluoride sampling bag was filled with 3 L of odorless air treated with activated charcoal into which 20 g of paint was poured and sealed. Then, after standing for 30 minutes in a room at room temperature of 23° C., ammonia concentration was measured using an ammonia gas detector tube manufactured by Gastech. The evaluation criteria were as follows.
○: 12 ppm by volume or less ×: Value exceeding 12 ppm by volume

<Odor (sensory evaluation)>
50 g of the paint was placed in a 100 ml glass bottle, and an odor sensory test was conducted in a room at room temperature of 23° C. by 10 panelists. "No odor", "Slight odor", and "Odor" are evaluated. 0 point is added for "No odor", 1 point is added for "Slight odor", and 2 points are added for "Odor". The paint odor was evaluated by The evaluation criteria were as follows.
○: The total score of 10 people is 4 points or less.
x: The total score of 10 persons is 5 points or more.

<Feeling of tack>
Under standard conditions (temperature 23 ° C., relative humidity 50%), paint is applied to a glass plate of 150 × 70 × 2 mm with a film applicator with a gap of 150 μm, dried for 7 days, and then coated with the pad of a finger. The tack feeling was evaluated according to the following criteria based on the feeling of touching the surface.
⊚+: There is no stickiness to the finger even when the finger is strongly pressed.
⊚: Slightly sticky when pressed strongly with a finger.
◯: Slightly sticky when pressed with a finger.
x: There is a feeling of stickiness.

<Low temperature film formability>
Under the conditions of 5 ° C., the paint was applied to a 150 × 70 × 2 mm glass plate with a 6 mil applicator, dried under the same conditions for 24 hours, and then returned to room temperature (23 ° C.). From the appearance of , the low-temperature film-forming properties were evaluated according to the following criteria.
⊚: No cracks or peeling of the paint film was observed.
◯: Fine cracks at a level that cannot be visually confirmed are observed in the coating film.
x: Abnormalities such as cracks and peeling of the coating film.

<Water resistance>
The paint was applied with a brush to a flexible board of 150×70×4 mm under standard conditions (temperature 23° C., relative humidity 50%). After drying for 6 hours, a second layer was applied in the same manner and dried for 14 days to obtain a test piece. The obtained test piece was immersed in ion-exchanged water (23° C.) for 96 hours and then taken out. From the appearance of the test piece 2 hours after taking out, the water resistance was evaluated according to the following criteria. The gloss change rate was calculated from the specular gloss at a geometric angle of 60° using the following formula.
R=|G ₀ −G ₁ |/G ₀ ×100
(R: gloss change rate, G ₀ : specular glossiness before water resistance test, G ₁ : specular glossiness after water resistance test)
⊚+: The rate of change in luster before and after the water resistance test is 5% or less.
⊚: Change rate of gloss before and after water resistance test is 6 to 10%.
◯: Change in luster before and after the water resistance test is 11 to 20%.
x: Change rate of gloss before and after the water resistance test is more than 20%.

<60° gloss>
Under standard conditions (temperature of 23° C., relative humidity of 50%), the paint was applied to a glass plate of 150×70×2 mm with a film applicator with a gap of 150 μm, and dried for 48 hours. Specular gloss at a geometric angle of 60° was measured for the obtained test piece.

The "solid content concentration" in the table has the same meaning as the "content of non-volatile matter". In addition, "total (parts by mass)" indicates the total parts by mass of the components contained in the paint, and "non-volatile content (mass%)" is the non-volatile content (mass%) contained in the paint. , "content of organic compounds with a boiling point of 260 ° C. or lower" indicates the content (% by mass) of organic compounds with a boiling point of 260 ° C. or lower in the paint, and "mass ratio of acrylic resin A / acrylic resin B" is , shows the mass ratio of acrylic resin A (synthesis examples A1 to A9) and acrylic resin B (synthesis examples B1 to B14) contained in the paint.

Claims (6)

An acrylic resin (A) having a glass transition temperature of less than 5°C, an acrylic resin (B) having a glass transition temperature of 20 °C or more and 100°C or less, alkaline inorganic compounds other than ammonia, and alkaline organic compounds having a boiling point of more than 260°C. and a neutralizing agent (C) selected from the group consisting of: the acrylic resin (A) and the acrylic resin (B) are each dispersed in the form of an emulsion, wherein the acrylic resin The mass ratio (A)/(B) between (A) and the acrylic resin (B) is 50/50 to 90/10, and the content of organic compounds having a boiling point of 260° C. or less is 3.0% by mass or less. , the ammonia concentration measured by the ammonia concentration measurement method described below is 12 ppm by volume or less, the glossiness at 60 ° of the coating film obtained from the water-based coating composition is 10 or more, and the acrylic resin ( A water-based coating composition characterized in that one or both of A) and the acrylic resin (B) contain a crosslinked structure :
<Method for measuring ammonia concentration>
A 3 L polyvinyl fluoride sampling bag is filled with 3 L of odorless air, 20 g of the coating composition is poured into the sampling bag, and the sampling bag is sealed. Then, after standing at 23° C. for 30 minutes, the ammonia concentration in the sampling bag is measured using an ammonia gas detector tube. The water-based coating composition according to claim 1, wherein the acrylic resin (B) has a glass transition temperature of 20 to 70°C. 3. The water-based coating composition according to claim 1, wherein the glossiness at 60° of the coating film obtained from the water-based coating composition is 70 to 90. 4. The water-based coating composition according to any one of claims 1 to 3, further comprising a coloring pigment (D). The water-based coating composition according to any one of claims 1 to 4, which does not contain an organic compound having a boiling point of 260°C or less. A coated article obtained by applying the water-based coating composition according to any one of claims 1 to 5 to an interior base material of a building.