Base adjustment water-based coating material composition, base adjustment method using the same, and coated finish structure

Abstract

To provide an aqueous coating material composition for substrate adjustment which is excellent in quick drying property and low temperature curability, has both water vapor permeability and water-shielding property, has sufficient elongation physical property and substrate followability, and has viscosity and a TI value suitable for construction by a roller brush.SOLUTION: An aqueous coating material composition for substrate adjustment is composed of crosslinked type acrylic resin-based emulsion having a glass transition temperature of -20 to 10°C, nano-composite emulsion in which a micelle with a particle diameter of 60-120 nm formed of an acrylic resin containing one or two or more silica particles with a primary particle diameter of 15-30 nm and an emulsifier is dispersed in water, a water-soluble cationized polymer, a volatile base, a filler, an organic thickener, a film formation auxiliary and a pigment, and has a pH of the whole composition of 9.5-11.5.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an aqueous primer coating composition used for the purpose of adjusting the surface of a substrate on which a coating finish material is applied, a primer coating method using the same, and a coating finish structure.

Background Art

[0002] Conventionally, a coating finish applied to the outer wall of a building or the like is finished using a primer or an undercoat, an intermediate coat if necessary, and a topcoat.

[0003] Patent Document 1 proposes a primer (I) containing a copolymer aqueous dispersion (A) having a glass transition temperature of -20°C or lower. On the coating film of the primer (I), a copolymer aqueous dispersion (B) having a glass transition temperature of the copolymer of -60 to 0°C and a copolymer aqueous dispersion (C) having a glass transition temperature of the copolymer of 15 to 50°C are solid content mass ratios of (B) / (C). A coating finish method has been proposed in which a topcoat paint (II) is applied at a ratio of 20 / 80 to 80 / 20, and it has been shown that it can follow cracks in the substrate and has excellent waterproof properties. However, aqueous compositions such as the primer and topcoat paint of Patent Document 1 cause resin fusion due to the evaporation of water, which is a solvent, during the coating film formation process. However, since the evaporation rate of water is slow, it takes time to form a coating film, and there is a problem that it may not have quick-drying properties. In addition, in a low-temperature environment where the evaporation rate of water particularly decreases, a coating film with insufficient drying may be formed, resulting in poor coating film formation, or whitening of the coating film may occur due to the difference in the refractive index of light between water and resin.

[0004] In order to solve the above problems, Patent Document 2 proposes a storage-stable aqueous composition suitable for a traffic paint having quick-drying properties, which comprises: (a) an aqueous dispersion of an anionically stabilized polymer; (b) a water-soluble polyfunctional amine polymer; and (c) a suspension or dispersion of a phyllosilicate in a volatile base, wherein the concentration of the phyllosilicate is 1% by weight to 18% by weight based on the total weight of the suspension or the dispersion. The volatile base is used in an amount such that the composition has a pH at which substantially all of the polyfunctional amine polymer is in a non-ionic state.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

[0006] However, the storage-stable aqueous composition of Patent Document 2 has a problem in that it may have no water vapor permeability in some cases such as when it does not contain an aggregate, and as a result, swelling or peeling may occur in the coating film.

[0007] In addition, since the composition of Patent Document 2 contains a synthetic phyllosilicate which is an inorganic thickener, it has a problem that preliminary mixing is required during production, which is time-consuming. Also, high-speed stirring for a long time may be required to uniformly disperse it, resulting in high costs. Further, when a clay-based material such as synthetic phyllosilicate is blended, the composition may be colored by the material, making it difficult to adjust the color tone, and may have an adverse effect on the hiding power and the color development of the topcoat.

Summary of the Invention

Problems to be Solved by the Invention

[0008] The problem to be solved by the present invention is to provide an aqueous coating composition for substrate conditioning that has quick-drying properties, excellent curability in a low-temperature environment, good water vapor permeability so that swelling or peeling of the coating film caused by moisture contained in the substrate does not occur, has water-blocking properties despite having such water vapor permeability, has good substrate followability, excellent storage stability, does not require premixing or long-time high-speed stirring when blending a thickener, and has a viscosity and TI value (thixotropic index) suitable for application with a roller or brush, a substrate conditioning method using the same, and a coating finish structure.

Means for Solving the Problem

[0009] In order to solve the above problems, the invention according to claim 1 is a composition containing a crosslinked acrylic resin emulsion having a glass transition temperature of -20 to 10°C, an acrylic resin containing one or more silica particles having a primary particle diameter of 15 to 30 nm, a nanocomposite emulsion in which micelles having a particle diameter of 60 to 120 nm formed by the acrylic resin and an emulsifier are dispersed in water, a water-soluble cationized polymer, a volatile base having a boiling point of 100°C or lower, a filler, an organic thickener, a film-forming aid, and a pigment, The weight ratio of the solid content of the crosslinked acrylic resin emulsion to the solid content of the nanocomposite emulsion is 4 to 15:1, The silica particles are 10 to 20 parts by weight per 100 parts by weight of the nanocomposite emulsion, The blending amount of the water-soluble cationized polymer is 0.2 to 1.2 parts by weight per 100 parts by weight of the entire composition, The pH of the entire composition is 9.5 to 11.5, and provides an aqueous coating composition for substrate conditioning characterized by this.

[0010] The invention according to claim 2 provides the aqueous coating composition for substrate conditioning according to claim 1, characterized in that the water-soluble cationized polymer is a polyalkyleneimine compound.

[0011] The invention according to claim 3 is that the volatile base is ammonia, carbon number C 1 -C4 Provided is the aqueous coating composition for substrate conditioning according to claim 1 or claim 2, which is characterized by comprising any one or a mixture of two or more of lower alkylamines and dimethylaminomethanol.

[0012] The invention according to claim 4 provides the aqueous coating composition for substrate conditioning according to any one of claims 1 to 3, wherein the organic thickener is a urethane-modified polyether having a weight average molecular weight (Mw) of 10,000 to 35,000.

[0013] The invention according to claim 5 provides the aqueous coating composition for substrate conditioning according to any one of claims 1 to 4, wherein the viscosity of the composition is 60 to 150 Pa·s / 23°C at 2 rpm of a BH viscometer, and the TI value of the composition obtained by dividing the viscosity of the composition at 2 rpm of the BH viscometer by the viscosity at 20 rpm is 4 to 7.

[0014] The invention according to claim 6 provides a substrate conditioning method, which is characterized by coating the aqueous coating composition for substrate conditioning according to any one of claims 1 to 5 on the substrate at least twice with a coating thickness of 0.15 to 0.5 mm.

[0015] The invention according to claim 7 provides a coating finish structure, which is characterized by comprising an aqueous coating composition layer for substrate conditioning formed by coating the aqueous coating composition for substrate conditioning according to any one of claims 1 to 5, and a topcoat layer formed by coating a topcoat material on the aqueous coating composition layer for substrate conditioning at least once.

Advantages of the Invention

[0016] The aqueous coating composition for substrate adjustment of the present invention has the effect of having quick-drying properties. This is presumably based on the fact that the acrylic resin polymer in the crosslinked acrylic resin-based emulsion and the nanocomposite emulsion contains micelles (anionic micelles) that are charged with anions, and the water-soluble cationized polymer aggregates due to electrical interaction, promoting the fusion and fixation of the acrylic resin polymer. Since the quick-drying property also works in a low-temperature environment where the moisture in the composition is difficult to evaporate, it has the effect of suppressing the whitening of the coating film and the poor formation of the coating film that may occur when a general aqueous coating composition is used in a low-temperature environment. In addition, the aqueous coating composition for substrate adjustment of the present invention has a sufficient pot life (usable time) for good coating application even in a high-temperature environment such as in summer, and has the effect of having good coating workability.

[0017] In addition, although the aqueous coating composition for substrate adjustment of the present invention is an aqueous coating composition, it forms a dense coating film and contains nano-sized silica particles, so it has the effect of having both water vapor permeability and water barrier properties. It is presumed that the nano-sized silica particles are dispersed in the coating film to form a pore structure of a size that cannot be visually confirmed, resulting in a porous coating film through which water vapor can permeate.

[0018] Due to this water vapor permeability, the moisture contained in the substrate permeates through the coating film formed by this composition as water vapor and is released, or moves in the coating film continuous direction. Therefore, no local water vapor pressure is applied to a part of the coating film. Also, even if moisture is continuously supplied to the substrate for some reason and accumulates at the interface with the coating film, the moisture can be released outside the coating film or in the coating film continuous direction as water vapor, so the occurrence of swelling and peeling of the coating film is suppressed (anti-swelling property).

[0019] In addition, since the aqueous base-coating composition of the present invention uses a crosslinked acrylic resin emulsion having a glass transition temperature of -20 to 10°C, it has the effect of being excellent in elongation physical properties and substrate followability. Even when a topcoat material conforming to the provisions of the architectural finish coating material of JISA 6909 is applied on the aqueous base-coating composition of the present invention to form a coating finish structure, there is an effect that peeling and cracking are less likely to occur in the coating film.

[0020] In addition, since the aqueous base-coating composition of the present invention uses an organic thickener instead of an inorganic thickener, it does not require preliminary mixing or long-time high-speed stirring during production, and as a result, it has the effect of being low-cost. Further, by setting the viscosity of the aqueous base-coating composition of the present invention to 60 to 150 Pa·s / 23°C and the TI value to 4 to 7 with the organic thickener, it is possible to apply it with good workability to a vertical substrate such as the outer wall of a building using a construction tool such as a roller brush so that the single-pass coating thickness is 0.15 to 0.5 mm.

[0021] In addition, the base-coating method according to claim 6 has the effect that by applying in at least two portions with a coating thickness of 0.15 to 0.5 mm, a coating thickness sufficient to fully exhibit both excellent water vapor permeability and water shielding property can be ensured with good coating workability without causing sagging. In addition, even when there is a large unevenness in the substrate, for example, an unevenness exceeding 0.5 mm, there is an effect that the large unevenness of the substrate can be adjusted without impairing the water vapor permeability and water shielding property.

[0022] Since the coating finish structure according to claim 7 has a substrate conditioning material layer excellent in water vapor permeability and substrate followability, there is an effect that swelling and peeling are less likely to occur. As described above, the substrate conditioning material layer has water vapor permeability, and this water vapor permeability allows water vapor to permeate not only in the thickness direction of the coating film but also in the continuous direction of the coating film. Therefore, whether the topcoat layer forming the coating finish structure has water vapor permeability or not, water vapor related to the moisture contained in the substrate can be released in the continuous direction of the coating film. As a result, local water vapor pressure is not applied to a part of the coating finish structure, and even if moisture is continuously supplied to the substrate for some reason and accumulates at the interface with the coating film, the moisture can be released as water vapor in the continuous direction of the coating film. Therefore, there is an effect that swelling and peeling do not occur due to these influences.

Mode for Carrying Out the Invention

[0023] Hereinafter, the present invention will be described in detail.

[0024] The aqueous coating material composition for substrate conditioning of the present invention comprises a crosslinked acrylic resin emulsion having a glass transition temperature of -20 to 10°C, an acrylic resin containing one or more silica particles having a primary particle diameter of 15 to 30 nm, and a nano composite emulsion in which micelles having a particle diameter of 60 to 120 nm formed by the acrylic resin and an emulsifier are dispersed in water, a water-soluble cationized polymer, a volatile base having a boiling point of 100°C or lower, a filler, an organic thickener, a film-forming aid, and a pigment. The weight ratio of the solid content of the crosslinked acrylic resin emulsion to the solid content of the nano composite emulsion is 4 to 15:1. The silica particles are 10 to 20 parts by weight per 100 parts by weight of the nano composite emulsion. The blending amount of the water-soluble cationized polymer is 0.2 to 1.2 parts by weight per 100 parts by weight of the whole composition. The pH of the whole composition is 9.5 to 11.5. It is an aqueous coating material composition for substrate conditioning, and if necessary, additives such as a dispersant, an antifoaming agent, a preservative, and an antifreezing agent can be blended in addition to these.

[0025] <Crosslinked acrylic resin emulsion> The crosslinked acrylic resin emulsion used in the present invention is the main component constituting the aqueous coating composition for substrate adjustment of the present invention. It is an aqueous resin in which an acrylic resin emulsified by an emulsifier to form micelles is dispersed in water together with a water-soluble crosslinking agent such as a hydrazine derivative to form an emulsion. The crosslinked type is used for the purpose of improving water barrier properties by improving elongation physical properties and making the coating film dense. As the emulsifier, an anionic emulsifier having a carboxylic acid, a sulfonic acid, or a phosphoric acid, etc. in the hydrophilic group and being charged to anions in an aqueous solution can be used. Therefore, the micelles constituting the crosslinked acrylic resin emulsion used in the present invention are charged to anions.

[0026] As the acrylic resin, an acrylic acid ester copolymer resin, a vinyl acetate-acrylic acid ester copolymer resin, a silicone-modified acrylic resin, etc. can be used. As the acrylic monomer for the acrylic resin, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, t-butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, nonyl acrylate, decyl acrylate, dodecyl acrylate, n-amyl acrylate, isoamyl acrylate, lauryl acrylate, stearyl acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, t-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, ethoxyethyl (meth)acrylate, methoxypropyl (meth)acrylate, ethoxypropyl (meth)acrylate, etc. can be used, and they can be used alone or in combination of two or more kinds.Examples of other unsaturated monomers include styrene derivatives such as styrene, α-methylstyrene, chlorostyrene, vinyltoluene, and methoxystyrene; carboxyl group-containing monomers such as (meth)acrylic acid, fumaric acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, and crotonic acid; (meth)acrylic acid, crotonic acid, and itaconic acid; hydroxyl group-containing monomers such as 2-hydroxyethyl (meth)acrylate, 2(3)-hydroxypropyl (meth)acrylate, 4-hydroxybutyl acrylate, allyl alcohol, and mono(meth)acrylic esters of polyhydric alcohols; amide group-containing monomers such as (meth)acrylamide and maleamide; amino group-containing monomers such as 2-aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, 3-aminopropyl (meth)acrylate, 2-butylaminoethyl (meth)acrylate, and vinylpyridine; epoxy group-containing monomers or oligomers obtained by reacting glycidyl (meth)acrylate, allyl glycidyl ether, or an epoxy compound having two or more glycidyl groups with an ethylenically unsaturated monomer having an active hydrogen atom; alkoxysilyl group-containing monomers such as vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 2-(meth)acryloxyethyltrimethoxysilane, 2-(meth)acryloxyethyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, 3-(meth)acryloxypropylmethyldipropoxysilane, 3-(meth)acryloxybutylphenyldimethoxysilane, 3-(meth)acryloxypropyldimethylmethoxysilane, and 3-(meth)acryloxypropyldiethylmethoxysilane; and others such as vinyl acetate, vinyl chloride, and further ethylene, butadiene, acrylonitrile, dialkyl fumarate, etc. can be used, and they can be used alone or in combination of two or more.

[0027] The crosslinking agent includes adipic acid dihydrazide, glutaric acid dihydrazide, isophthalic acid dihydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, itaconic acid dihydrazide, etc., which are carbonyl hydrazides, or hydrazine derivatives such as ethylene-1,2-dihydrazine, propylene-1,3-dihydrazine, butylene-1,4-dihydrazide, etc., which are alkyl hydrazides. These can be used alone or in combination of two or more. The compounding amount of the crosslinking agent is preferably 0.05 to 2.0 parts by weight per 100 parts by weight of the crosslinkable acrylic resin emulsion. If it is less than 0.05 parts by weight, the elongation physical properties may decrease, and if it exceeds 2.0 parts by weight, the coating film may become too dense and the water vapor permeability may decrease.

[0028] The glass transition temperature of the acrylic resin constituting the crosslinked acrylic resin emulsion of the present invention is preferably -20 to 10°C. When the glass transition temperature is less than -20°C, depending on the topcoat applied on the aqueous coating composition for substrate conditioning of the present invention, cracks may occur in the topcoat. This is because the glass transition temperature of a general topcoat is often about 20°C. When the difference in the glass transition temperature between the aqueous coating composition for substrate conditioning of the present invention and the topcoat exceeds approximately 30 to 40°C, the topcoat cannot follow the movement of the aqueous coating composition for substrate conditioning of the present invention that follows the movement of the substrate, and eventually cracks may occur in the topcoat. This is based on the fact that the cracks are less likely to occur when the topcoat is applied relatively thickly, such as several millimeters like a coating material, but are significantly likely to occur when the topcoat is applied relatively thinly, such as several tens of micrometers like a paint. On the other hand, when the glass transition temperature of the acrylic resin constituting the crosslinked acrylic resin emulsion of the present invention exceeds 10°C, the substrate followability may decrease. The glass transition temperature referred to here is a value measured by a differential scanning calorimeter (DSC). Further, the solid content of the crosslinked acrylic resin emulsion of the present invention is preferably 10 to 30 parts by weight in 100 parts by weight of the aqueous coating composition for substrate conditioning. If it is less than 10 parts by weight, various coating film strengths decrease, and if it exceeds 30 parts by weight, the coating workability decreases.

[0029] <Nanocomposite emulsion> The nanocomposite emulsion used in the present invention is an aqueous resin in which acrylic resin containing one or more silica particles having a primary particle diameter of 15 to 30 nm is emulsified by the action of an emulsifier to form micelles of 60 to 120 nm, and the micelles are dispersed in water. As the emulsifier, an anionic emulsifier having a carboxylic acid, sulfonic acid, phosphoric acid, etc. in the hydrophilic group and being charged anionic in an aqueous solution can be used. Therefore, the micelles constituting the nanocomposite emulsion used in the present invention are charged anionic.

[0030] The nanocomposite emulsion is contained for the purpose of imparting water vapor permeability to the aqueous coating composition for substrate conditioning of the present invention. It is presumed that this water vapor permeability is manifested by the formation of a pore structure through which water vapor can permeate by the nano-sized silica particles contained in the nanocomposite emulsion, and the movement of water vapor along the surface of the silica particles.

[0031] As the acrylic resin, those described in paragraph

[0026] can be used. Further, as the silica particles, those having a primary particle size in the nano-size range of 15 to 30 nm may be used, and those having unmodified SiOH groups present on the particle surface and those surface-modified with amino groups, carboxyl groups, etc. can be used, and there is no particular limitation. As a method for producing an acrylic resin containing nano-sized silica particles, for example, miniemulsion polymerization can be mentioned, in which submicron-sized monomer oil droplets (miniemulsion) containing the silica particles are generated by a method such as ultrasonic irradiation, and the monomer oil droplets are polymerized as they are to be converted into submicron-sized polymer fine particles. There is also a method of growing a polymer on the surface of the silica particles by graft polymerization. Emulsion polymerization is carried out using a silica particle surface-modified with an acrylic monomer-based silane coupling agent to grow the shell polymer layer in core-acrylic shell particles. When adjusting an acrylic resin containing nano-sized silica particles by these methods, there may be a case where only 1 silica particle is contained or a case where 2 or more are contained, and the weight ratio of the acrylic resin to the silica particles may be on average 1:3 to 3:1, and this weight ratio can be controlled by the production method, the type of acrylic resin, and additives used, etc. Further, the amount of the silica particles in 100 parts by weight of the nanocomposite emulsion is preferably 10 to 20 parts by weight. If it is less than 10 parts by weight, water vapor permeability may not be obtained, and if it exceeds 20 parts by weight, elongation physical properties and water barrier properties may decrease.

[0032] The blending amount of the nanocomposite emulsion is preferably such that the weight ratio of the solid content of the crosslinked acrylic resin emulsion to the solid content of the nanocomposite emulsion is 4 to 15:1. When the solid content of the nanocomposite emulsion is less than this range, as a result, the content of nanosized silica particles decreases and the water vapor permeability may be impaired. When the solid content of the nanocomposite emulsion exceeds this range, as a result, the content of the silica particles becomes excessive, and the denseness of the coating film may decrease and the water barrier property may be reduced.

[0033] <Water-soluble cationized polymer> The water-soluble cationized polymer used in the present invention is blended for the purpose of imparting quick-drying properties. Specifically, by electrically interacting with micelles (anionic micelles) charged with anions by the action of an anionic emulsifier constituting the crosslinked acrylic resin emulsion and the nanocomposite emulsion, it promotes the aggregation of resins without waiting for the fusion of resins due to the evaporation of water in the coating film formation process of a general aqueous composition, thereby promoting the coating film formation reaction. The water-soluble cationized polymer is in a state where all cationic functional groups are apparently neutral due to the interaction with a volatile base described later before the composition is applied, and does not cause an electrical interaction with the anionic micelles, and is controlled so that the composition does not aggregate during production or storage.

[0034] The water-soluble cationized polymer of the present invention is not particularly limited as long as it is a polymer having a cationic functional group. For example, a polyalkyleneimine compound having an amino group, a polyamide compound, an aminosulfopolyester compound, a polyallylamine compound, a polyvinylamine compound, and a basic nitrogen-containing polymer obtained by modifying these can be used. Preferably, it is a polyalkyleneimine compound obtained by ionic polymerization of an imine compound. Among them, polyethyleneimine obtained by polymerizing ethyleneimine is particularly preferred because the ratio of cationic functional groups in the molecule is large. The molecular weight is preferably such that the weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) is 600 to 200,000. When the weight average molecular weight (Mw) increases, the viscosity as an additive becomes high and it is difficult to handle. Therefore, more preferably, the weight average molecular weight (Mw) is 600 to 100,000. If it is less than 600, the quick-drying property may decrease due to a decrease in the aggregability with anionic micelles in the crosslinked acrylic resin-based emulsion and the nanocomposite emulsion. If it exceeds 100,000, the viscosity as an additive tends to increase in a low-temperature environment such as in winter, making it difficult to handle.

[0035] The blending amount of the water-soluble cationized polymer is appropriately adjusted according to its type, molecular weight, and the ratio of cationic functional groups in the molecule. However, in the aqueous coating composition for substrate adjustment of the present invention, 0.2 to 1.2 parts by weight is preferably used per 100 parts by weight of the aqueous coating composition for substrate adjustment. If it is less than 0.2 part by weight, the quick-drying property may decrease. If it exceeds 1.2 parts by weight, the pot life may be shortened, which may have an adverse effect on the coating workability.

[0036] <Volatile base> The volatile base used in the present invention interacts with the cationic functional groups of the above-mentioned water-soluble cationized polymer until the aqueous base-adjusting coating composition of the present invention is manufactured and applied to the substrate, so that the cationic functional groups are seemingly in a neutral state, suppressing aggregation with anionic micelles in the crosslinked acrylic resin emulsion and the nanocomposite emulsion, and is compounded for the purpose of improving the storage stability of the composition. The volatile base refers to a base that easily volatilizes into the atmosphere at standard atmospheric pressure (1 atm or 760 mmHg), and examples include ammonia, morpholine, lower alkylamines having C 1 -C 5 , dimethylaminomethanol, 2-dimethylaminoethanol, N-methylmorpholine, ethylenediamine, or a mixture thereof, etc. The volatile base is usually in the form of an aqueous solution. In the aqueous base-adjusting coating composition of the present invention, it is more preferable to use a volatile base having a boiling point of 100°C or lower in order to make the quick-drying property sufficient. Specifically, ammonia, lower alkylamines having C 1 -C 4 , dimethylaminomethanol, etc. are mentioned. In particular, an aqueous solution of ammonia is inexpensive and low-cost.

[0037] The compounding amount of the volatile base is preferably an amount such that the pH of the aqueous base-adjusting coating composition of the present invention is 9.5 to 11.5, and it depends on the basicity of the volatile base used. If the amount is such that the pH is less than 9.5, the storage stability may decrease. If the amount is such that the pH exceeds 11.5, it may take time for the volatile base to volatilize, resulting in a decrease in the quick-drying property, or the odor of the volatilized base may become intense and have an adverse effect on the working environment.

[0038] In addition, since the volatile base lowers the freezing point of water when dissolved in water, it also has an effect as an antifreeze in the aqueous base-adjusting coating composition of the present invention using water as a solvent. This effect has the effect of synergistically improving the antifreeze effect when used in combination with a commercially available antifreeze.

[0039] <Filler> The filler of the present invention refers to those with an average particle size D50 (particle size at 50% cumulative by weight) of less than 100 μm, and does not contain synthetic layered silicate, which is compounded in an amount of 5 parts by weight or less per 100 parts by weight of the whole composition and is also treated as a thickener. For the purpose of adjusting the viscosity and coating properties of the composition, heavy calcium carbonate, clay, kaolin, talc, precipitated barium sulfate, barium carbonate, silica powder, etc. can be used. Among them, heavy calcium carbonate is inexpensive and can reduce the cost burden. The compounding amount of the filler is preferably 25 to 45 parts by weight, more preferably 30 to 40 parts by weight, per 100 parts by weight of the whole aqueous coating composition for substrate adjustment. If it is less than 25 parts by weight, the hiding power is insufficient, such as the color of the substrate showing through. If it exceeds 45 parts by weight, the viscosity of the composition becomes high and the coating workability may become poor. Also, if it is less than 30 parts by weight, the hiding power may decrease depending on the color tone, and if it exceeds 40 parts by weight, the coating workability tends to decrease in a low-temperature environment such as in winter.

[0040] <Organic thickener> The organic thickener of the present invention is compounded for the purpose of improving the coating workability and improving the water retention property to prevent the aggregation of the composition during storage. It is not particularly limited as long as the viscosity of the aqueous coating composition for substrate adjustment of the present invention is 60 to 150 Pa·s / 23°C and the TI value is 4 to 7. Water-soluble cellulose ether, urethane-modified polyether, polycarboxylic acid, or a mixture thereof can be used. Since it is preferable to keep the pH of the composition within the range of 9.5 to 11.5 from the viewpoint of storage stability of the aqueous coating composition for substrate adjustment of the present invention, it is preferable to use urethane-modified polyether, which hardly affects the pH of the composition, as the organic thickener. Of course, even if other organic thickeners that can affect the reduction of pH are used, as long as the pH of the composition can be adjusted within the range of 9.5 to 11.5 by adjusting the compounding amount of the volatile base, any of them can be used without problems.

[0041] The blending amount of the organic thickener of the present invention is preferably 0.1 to 5.0 parts by weight in 100 parts by weight of the base-adjusting water-based coating composition. If it is less than 0.1 part by weight, a sufficient thickening effect cannot be obtained, which may cause sagging when the composition is applied. If it exceeds 5.0 parts by weight, the coating workability may deteriorate. Further, the organic thickener preferably has a weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) of 10,000 to 35,000. If it is less than 10,000, the thickening effect may be insufficient. If it exceeds 35,000, it may thicken excessively and have an adverse effect on the coating workability.

[0042] In addition, as thickeners used in water-based compositions, there are also inorganic thickeners such as silicates, metal silicates, montmorillonite, and colloidal alumina. However, inorganic thickeners often have poor dispersibility, and it is necessary to perform preliminary mixing to prepare a mill base before mixing with the water-based resin, and it may be necessary to stir at high speed for a long time to disperse them uniformly, which may be time-consuming and costly. Further, even if an inorganic thickener is used in this way, coloring such as mineral-derived mud may occur, which may have an adverse effect on the hiding property of the base and the color development of the topcoat. Therefore, it is preferable to use an organic thickener in the present invention.

[0043] <Film-forming aid> The film-forming aid used in the present invention is blended for the purpose of promoting the fusion of polymer particles of acrylic resin in the crosslinked acrylic resin-based emulsion and the nanocomposite emulsion and forming a uniform film, and ethylene glycol diethyl ether, ethylene glycol monoethyl ether acetate, benzyl alcohol, butyl cellosolve, ester alcohol, or a mixture thereof can be used. The blending amount of the film-forming aid is preferably 0.5 to 10 parts by weight in 100 parts by weight of the base-adjusting water-based coating composition. If it is less than 0.5 part by weight, film formation may be insufficient in a low-temperature environment such as winter. If it exceeds 10 parts by weight, the surface of the coating film may become sticky and easily contaminated.

[0044] <Pigment> As the pigments used in the present invention, inorganic pigments such as titanium oxide, zinc oxide, carbon black, ferric oxide (red iron oxide), lead chromate, yellow lead, and yellow iron oxide can be used. Among them, titanium oxide is excellent in the hiding power of the base layer and can be used as the main pigment for imparting hiding power because it is white.

[0045] In addition to the above, it is preferable to incorporate into the aqueous coating composition for substrate adjustment of the present invention, defoamers, preservatives, dispersants, anti-algal and anti-fungal agents, and anti-freezing agents generally used in aqueous compositions.

[0046] The aqueous coating composition for substrate adjustment of the present invention can be applied to mortar substrates, concrete substrates, panels made of autoclaved lightweight aerated concrete (ALC panels), ceramic siding substrates, and painted substrates. Examples of the painted substrates include coatings of acrylic resin-based, acrylic urethane resin-based, polyurethane resin-based, fluororesin-based, silicone acrylic resin-based, vinyl acetate resin-based, and epoxy resin-based. In order to maintain sufficient adhesion to the aqueous coating composition for substrate adjustment of the present invention, it is desirable to perform a substrate treatment suitable for each substrate and use a clean and dry substrate.

[0047] Further, among the above substrates, there are those having portions where the butting portions and joint portions of the panels are sealed. In such portions, the movement of the substrate is particularly intense and cracks are likely to occur in the coating film. In order to solve this problem, before applying the aqueous coating composition for substrate adjustment of the present invention, by attaching a fiber sheet having flexibility and air permeability such as a non-woven fabric, it is possible to suppress the occurrence of cracks in the aqueous coating composition for substrate adjustment of the present invention and the coating finish structure applied thereon. For attaching the non-woven fabric, for example, a composition obtained by adding 25 to 45 parts by weight of fibrous aggregate and 5 to 10 parts by weight of water to 100 parts by weight of the aqueous coating composition for substrate adjustment of the present invention and mixing them can be used. Examples of the fibrous aggregate include wollastonite ore, and those having a fiber length of 100 to 1500 μm and a fiber diameter of 20 to 80 μm are preferable because the impregnation of the composition into the fiber sheet is good.

[0048] In the application of the aqueous coating composition for substrate adjustment of the present invention, a roller brush can be used, and it is suitable for coating to a thickness of 0.15 to 0.5 mm. Of course, other painting tools or the like may be used as long as it can be coated to a thickness of 0.15 to 0.5 mm.

[0049] The aqueous coating composition for substrate adjustment of the present invention preferably has a viscosity of 60 to 150 Pa·s / 23°C and a TI value of 4 to 7 for coating workability and sag prevention. The viscosity is the viscosity measured at a rotational speed of 2 rpm using a BH-type viscometer TVB-10 (manufactured by Toki Sangyo Co., Ltd., trade name), and the TI value is the value measured in accordance with JIS A 6024. When the temperature is high, the viscosity tends to decrease and sag is likely to occur. On the other hand, when the temperature is low, the viscosity increases and the coating workability decreases. Therefore, an appropriate amount of water can be added to adjust the viscosity within a range where various physical properties evaluated below do not decrease significantly. To prevent these problems, it is preferably used at a temperature of 5 to 35°C.

[0050] Also, the aqueous coating composition for substrate adjustment of the present invention preferably has a single coating thickness of 0.15 to 0.5 mm, and when coated two or more times, the total thickness is preferably 0.3 to 1.0 mm. If it is less than 0.3 mm, the water shielding property may decrease, and if it exceeds 1.0 mm, the water vapor permeability may decrease. Also, when the single coating thickness exceeds 0.5 mm, the quick-drying property may decrease. Also, when the substrate is porous and the absorption of the coated composition is intense, it is necessary to increase the number of coatings to obtain a sufficient film thickness.

[0051] Hereinafter, the details of the quick-drying property, storage stability, water vapor permeability, and water shielding property, which are the effects of the aqueous coating composition for substrate adjustment of the present invention, will be described.

[0052] The quick-drying property of the aqueous coating composition for substrate adjustment of the present invention is exhibited by the electrical interaction between anionic micelles containing acrylic resin polymers in a crosslinked acrylic resin emulsion and a nanocomposite emulsion, and a water-soluble cationized polymer. It is considered that the anionic micelles and the water-soluble cationized polymer in this electrical interaction state aggregate, promoting the fusion and fixation of the polymers. In the film formation process of conventional aqueous coating compositions, resin fusion occurs due to the evaporation of water, whereas in the aqueous coating composition for substrate adjustment of the present invention, resin fusion is promoted without waiting for water evaporation by this mechanism, so it is considered that quick-drying property can be obtained.

[0053] Incidentally, there was a problem that the above-mentioned quick-drying property could also occur during the production and storage of the aqueous coating composition for substrate adjustment of the present invention. However, the present inventor has successfully solved this problem by blending a volatile base having a boiling point of 100°C or lower into the composition. The aqueous coating composition for substrate adjustment of the present invention is prepared by adding a water-soluble cationized polymer in the presence of a crosslinked acrylic resin emulsion and a nanocomposite emulsion. Before adding the water-soluble cationized polymer, a volatile base is added in advance to make the pH of the whole composition basic in the range of 9.5 to 11.5. When the water-soluble cationized polymer is added, the volatile base interacts with the cationic functional groups of the water-soluble cationized polymer, causing the water-soluble cationized polymer to behave as if it were neutral. As a result, the water-soluble cationized polymer does not interact electrically with the anionic micelles of the crosslinked acrylic resin emulsion and the nanocomposite emulsion, that is, it is designed so that they do not aggregate during production and storage. By controlling the pH of the whole composition using a volatile base in this way, good storage stability has been obtained in the aqueous coating composition for substrate adjustment of the present invention.

[0054] On the other hand, when the coating film is formed, the volatile base volatilizes, the cationic functional groups of the water-soluble cationized polymer are exposed, and the quick-drying property by the above mechanism is exhibited, promoting the formation of the coating film.

[0055] Moreover, one of the major features of the aqueous coating composition for substrate adjustment of the present invention is that it has both water vapor permeability and water resistance, which is due to the use of a crosslinked acrylic resin-based emulsion and a nanocomposite emulsion. The crosslinked acrylic resin-based emulsion increases the crosslink density of the resin, forming a dense coating film and providing water resistance. On the other hand, the nano-sized silica particles contained in the nanocomposite emulsion are dispersed in the coating film but do not chemically bond with the acrylic resin, so there are extremely fine gaps around them. It is presumed that the continuous connection of these gaps forms a pore structure of a size that cannot be visually confirmed in the coating film, making the coating film porous and allowing water vapor to permeate.

[0056] The inventors discovered that water vapor permeability can be imparted by mixing nano-sized silica particles into a conventional acrylic resin-based emulsion. However, simply blending the silica particles into the existing acrylic resin-based emulsion makes it difficult for the silica particles to appear on the coating film surface, and it is also difficult to uniformly disperse the silica particles throughout the coating film. As a result, the water vapor permeability was not stable depending on the degree of dispersion. On the other hand, attempting to stabilize the water vapor permeability by increasing the amount of the silica particles added posed the problem of reducing water resistance and coating film strength. Through repeated trial and error and experiments, the inventors found that by using an appropriate amount of a nanocomposite emulsion containing nano-sized silica particles in acrylic resin in advance, the nano-sized silica particles can be uniformly dispersed throughout the coating film and also appear on the coating film surface, ultimately achieving a formulation with an excellent balance of water vapor permeability and water resistance.

[0057] In addition, the pore structure formed by the nano-sized silica particles is formed not only in the thickness direction of the coating film but also in the continuous direction of the coating film, and water vapor can permeate in the thickness direction and the continuous direction of the coating film. As shown in the following evaluation, even when the coating finish structure formed by applying a topcoat material having no water vapor permeability on the aqueous coating material composition for substrate adjustment of the present invention is subjected to a swelling resistance test, no swelling or peeling occurs in the coating finish structure. Therefore, even if a topcoat material having no water vapor permeability is applied on the aqueous coating material composition for substrate adjustment of the present invention, due to the water vapor pressure related to the moisture contained in the substrate, or for some reason, moisture is continuously supplied to the substrate and accumulates at the interface with the coating film, and if the moisture cannot escape as water vapor, a coating finish structure that does not cause swelling or peeling can be formed. Of course, in order to further improve the performance of the coating finish structure, for example, it is preferable to form a coating finish structure by applying a topcoat material having water vapor permeability by increasing the aggregate content.

[0058] As the topcoat material for forming the coating finish structure of the present invention, various topcoat materials can be used regardless of the presence or absence of water vapor permeability as described above. Examples of commercially available topcoat materials having water vapor permeability include Jolyput Fresh JQ-800 (acrylic resin emulsion paint, resin content: 10 to 20 parts by weight, aggregate and filler: 40 to 60 parts by weight, manufactured by Aika Kogyo Co., Ltd., trade name). Examples of those having no water vapor permeability include Jolyput Top Silicone JC-870 (acrylic silicone resin emulsion paint, resin content: 60 to 70 parts by weight, pigment: 10 to 20 parts by weight, manufactured by Aika Kogyo Co., Ltd., trade name), and Aika Linopaint Silicone JCS-H1 (two-component weak solvent silicone paint, resin content 50 to 60 parts by weight, pigment: 10 to 20 parts by weight, manufactured by Aika Kogyo Co., Ltd., trade name), etc., which can be used for forming the coating finish structure of the present invention.

[0059] Hereinafter, it will be specifically described with reference to Examples and Comparative Examples.

Examples

[0060] <Examples and Comparative Examples> According to the formulations in Table 1 and Table 2, aqueous base-adjusting coating compositions of the examples and comparative examples were prepared. In Table 1 and Table 2, Acronal YJ2741D (solid content: 56%, glass transition temperature of the resin: -14 °C, copolymer of acrylic and styrene, containing 0.1 to 1.0 wt% of carbonyl hydrazide as a crosslinking agent, manufactured by BASF, trade name) was used as the crosslinked acrylic resin emulsion, Primacor EC-1791 (solid content: 55%, glass transition temperature of the resin: -40 °C, copolymer of acrylic, manufactured by DOW, trade name) was used as the non-crosslinked acrylic resin emulsion, Col.9 1200 (solid content: 40%, silica content: 15%, primary particle diameter of silica particles: 15 to 30 nm, average particle diameter of micelles: 90 nm, glass transition temperature of the resin: 2 °C, copolymer of acrylic, manufactured by BASF, trade name) was used as the nanocomposite emulsion, Lupasol FG (polyethyleneimine, solid content: 99%, weight average molecular weight (Mw): 800, manufactured by BASF, trade name) was used as the water-soluble cationized polymer, 25% aqueous ammonia solution (boiling point: 37.7 °C) was used as the volatile base, and heavy calcium carbonate WA (average particle diameter D 50: 10 μm, manufactured by Shiraishi Calcium Co., Ltd., product name), as organic thickener A, Nopco 700N (weight average molecular weight (Mw): 25,600, manufactured by San Nopco Ltd., product name) was used, as organic thickener B, SN Thickener 665T (weight average molecular weight (Mw): 19,800, manufactured by San Nopco Ltd., product name) was used, as film-forming aid A, Texanol CS-12 (manufactured by Chisso Corporation, product name) was used, as film-forming aid B, ethylene glycol monoethyl ether acetate (manufactured by OXITENO) was used, as pigment, titanium oxide R-820 (manufactured by Ishihara Sangyo Co., Ltd., product name) was used, and as other additives, defoamers, dispersants, preservatives, and antifreeze agents were added, appropriately selected from commercially available additives used in aqueous compositions. In addition, the blending amounts were adjusted so that the sum of the solid content of the crosslinked acrylic resin emulsion or non-crosslinked acrylic resin emulsion and the solid content of the nanocomposite emulsion in each example and comparative example would be equal. Also, Table 1 and Table 2 show the weight ratio of the solid content of the crosslinked acrylic resin emulsion or non-crosslinked acrylic resin emulsion to the solid content of the nanocomposite emulsion, and the pH of the composition.

[0061] <Production Method> This is the production method of the aqueous coating composition for substrate adjustment in Examples and Comparative Examples. First, a crosslinked acrylic resin emulsion or non-crosslinked acrylic resin emulsion, a nanocomposite emulsion, a filler, a film-forming aid, a pigment, and other additives were weighed into a specific container, mixed for about 5 minutes to make it uniform, then a volatile base was added and mixed for about 1 minute to disperse it uniformly. Next, an organic thickener was added and mixed, and a water-soluble cationized polymer was added and mixed for about 5 minutes to disperse it uniformly, thereby producing the aqueous coating composition for substrate adjustment in Examples and Comparative Examples. Finally, the pH of the composition was measured using a pH meter. The produced aqueous coating composition for substrate adjustment was transferred to a sealed container to prevent the volatile base from volatilizing and stored in an environment of 23°C and 50% RH until used for evaluation.

[0062]

Table 1

[0063]

Table 2

[0064] <Evaluation Method for Substrate-Adjusting Waterborne Coating Composition> The following evaluations were conducted on the substrate-adjusting waterborne coating compositions of the above Examples and Comparative Examples. Unless otherwise specified, the preparation, curing, and evaluation tests of the specimens were carried out under the environment of 23°C and 50% RH.

[0065] <Quick Drying / Curing Property> The substrate-adjusting waterborne coating composition of the Example or Comparative Example was applied to a glass plate using a roller brush at an application rate of 0.4 kg / m 2 . After 1.5 hours, the drying status was observed visually and by touch. Those that formed a smooth coating film without drying and whitening were rated as ○, those with only the surface dried and the inside of the coating film uncured (so-called skinning state) were rated as △, and those that were not dried, whitened, or had poor curing were rated as ×.

[0066] The tests were also carried out and evaluated in the same manner at 35°C, 5°C, and -5°C.

[0067] <Coating Workability> Using the ceramic siding specified in JIS A5422, which was set up horizontally and vertically as the substrate, the substrate-adjusting waterborne coating compositions of the Examples and Comparative Examples were applied with a roller brush at an application rate of 0.4 kg / m 2 , and the coating workability was confirmed. Those without dripping and splashing during coating were rated as ○, those without dripping but with poor coating workability due to the progress of aggregation and curing of the composition or with splashing were rated as △, and those with dripping, severe splashing, or the composition hardened during coating and unable to be coated were rated as ×. Note that the splashing refers to the composition scattering around or onto the operator when the roller brush is rolled for coating.

[0068] The coating workability was also confirmed and evaluated in the same manner at 35°C, 5°C, and -5°C.

[0069] <Viscosity / TI value> For the aqueous coating compositions for substrate adjustment of the examples and comparative examples, the viscosity at a rotational speed of 2 rpm and the viscosity at a rotational speed of 20 rpm were measured using a BH-type viscometer TVB-10 (manufactured by Toki Sangyo Co., Ltd., trade name). The TI value (thixotropic index) was determined in accordance with JIS A 6024, and was obtained by dividing the viscosity at 2 rpm by the viscosity at 20 rpm. Those with a viscosity at 2 rpm of 60 to 150 Pa·s were evaluated as ○, and those otherwise were evaluated as ×. Those with a TI value of 4 to 7 were evaluated as ○, and those otherwise were evaluated as ×.

[0070] <Elongation property> The aqueous coating compositions for substrate adjustment of the examples and comparative examples were applied with a roller brush to a thickness of 0.5 mm, cured for 1 hour, and dried. The same aqueous coating composition for substrate adjustment was applied to a thickness of 0.5 mm to make a total thickness of 1.0 mm, cured for 1 week to prepare a coating film sheet, and punched into a dumbbell shape No. 3 specified in JIS K 6251 to obtain a test piece. The test piece was subjected to a tensile performance test specified in JIS A 6021 to measure the elongation at break. Those with an elongation at break of 230% or more were evaluated as ○, and those less than 230% were evaluated as ×.

[0071] <Water vapor permeability> The aqueous coating compositions for substrate adjustment of the examples and comparative examples were applied to one side of a circular filter paper (diameter 150 mm, thickness 0.2 mm, manufactured by Whatman, grade 41) at an application amount of 0.4 kg / m 2 using a roller brush, cured for 1 hour, and dried. Then, the same aqueous coating composition for substrate adjustment was applied at an application amount of 0.4 kg / m 2It was applied with a roller brush and cured for one week to obtain a test piece. 400 mL of water was put into a cylindrical aluminum alloy cup with a height of 75 mm and a diameter of 140 mm. The test piece was placed on the upper part of the cup with the coated surface facing up. The end of the test piece was sealed to prevent water vapor from escaping through the gap between the test piece and the cup, and it was left standing for 3 days. After standing, the weight of the entire container was measured, and this value was taken as the value before the test. After further standing for 7 days, the weight of the entire container was measured as the value after the test. The value obtained by dividing the decrease in the weight of the entire container before and after the test by the number of test days was defined as the water vapor permeability (g / day). Those with a water vapor permeability (g / day) of 0.6 or more were evaluated as ○, indicating excellent water vapor permeability, and those with a water vapor permeability of less than 0.6 were evaluated as ×, indicating insufficient water vapor permeability.

[0072] <Water repellency> For the flexible board (400×200 mm, thickness 4 mm) specified in JIS A 5430, the aqueous coating composition for substrate adjustment of the examples and comparative examples was applied with a roller brush so that the coating amount was 0.4 kg / m 2 After coating and curing for 1 hour and drying, the same aqueous coating composition for substrate adjustment was applied with a roller brush so that the coating amount was 0.4 kg / m 2 After coating and curing for 14 days to obtain a test piece. Using the prepared test piece, the water permeation amount in Test Method B of the water permeability test of JIS A6909 was measured. Those with a water permeation amount of 0.5 mL or less in this test method were evaluated as having water repellency and marked as ○, and those with a water permeation amount exceeding 0.5 mL were evaluated as not having water repellency and marked as ×.

[0073] <Swelling resistance> The test piece was prepared and tested by a method conforming to JIS A 6909. The aqueous coating composition for substrate adjustment of the examples or comparative examples was applied to the mortar (70×70 mm, thickness 20 mm) specified in JISR 5201 with a coating amount of 0.4 kg / m 2 using a roller brush, cured for 1 hour and dried. Then, the same aqueous coating composition for substrate adjustment was applied with a coating amount of 0.4 kg / m 2It was applied with a roller brush and dried. Then, the four sides of the mortar were water-stopped with a paste-like epoxy resin and cured for 14 days to obtain test specimens. The test specimens were subjected to 10 cycles of the cycle of "immersed in water at 23°C for 18 hours → at -20°C for 3 hours → at 50°C for 3 hours", and the presence or absence of swelling on the coating film surface was visually observed. Those without swelling were evaluated as ○, those with small swelling were evaluated as △, and the others were evaluated as ×.

[0074] <Storage stability> The viscosities of the aqueous coating compositions for substrate adjustment in the examples and comparative examples were measured with a BH-type viscometer TVB-10 (trade name, manufactured by Toki Sangyo Co., Ltd.), placed in a sealed container with a capacity of 500 mL, and allowed to stand in an atmosphere of 50°C for 60 days, and then the viscosity was measured again, and the viscosities before and after the test were compared. Also, the appearance was visually observed. Those without significant viscosity change, separation of the composition, and aggregation were evaluated as ○, those with slight viscosity change or small aggregates confirmed were evaluated as △, and those with any abnormality such as significant viscosity change, separation of the composition, and aggregation were evaluated as ×.

[0075] It was allowed to stand at 5°C for 60 days in the same manner as above, the viscosities before and after the test were compared, and the appearance was observed and evaluated in the same manner.

[0076] <Evaluation results of the aqueous coating composition for substrate adjustment> Table 3 and Table 4 show the evaluation results of the aqueous coating composition for substrate adjustment. Note that those not subjected to evaluation due to aggregation, curing, etc. of the composition are indicated as "-".

[0077]

Table 3

[0078]

Table 4

[0079] <Evaluation of the coating finish structure> Table 5 shows the composition of the coating finish structure and its evaluation results. As shown in Table 5, as the aqueous coating composition for substrate adjustment, Examples 2, 3, Comparative Example 3, and Comparative Example 4 were used. As the topcoat, Jolipat Fresh JQ-800 (acrylic resin emulsion paint, resin content: 10 - 20 wt%, aggregate and filler: 40 - 60 wt%, manufactured by Aika Industries Co., Ltd., trade name), which is a topcoat with water vapor permeability, was used as topcoat A, and Jolipat Top Silicone JC-870 (acrylic silicone resin emulsion paint, resin content: 60 - 70 wt%, pigment: 10 - 20 wt%, manufactured by Aika Industries Co., Ltd., trade name), which is a topcoat without water vapor permeability, was used as topcoat B. The coating finish structures of Examples I to IV and Comparative Examples I to IV were formed and the following evaluations were conducted. Unless otherwise specified, the preparation, curing, and evaluation tests of the specimens were carried out under the environment of 23°C and 50% RH.

[0080]

Table 5

[0081] <Water vapor permeability> Apply the aqueous coating composition for substrate adjustment of the examples and comparative examples in Table 5 to one side of a circular filter paper (diameter 150 mm, thickness 0.2 mm, manufactured by Whatman, grade 41) at an application rate of 0.4 kg / m 2 using a roller brush, cure for 1 hour and dry. Then, apply the same aqueous coating composition for substrate adjustment at an application rate of 0.4 kg / m 2 using a roller brush and dry to form a layer of the aqueous coating composition for substrate adjustment. Then, apply topcoat A at an application rate of 0.35 kg / m 2 , or apply topcoat B at an application rate of 0.15 kg / m 2 using a roller brush, dry for 5 hours or more, and then apply topcoat A again at an application rate of 0.35 kg / m 2 , or apply topcoat B at an application rate of 0.15 kg / m 2It was applied with a roller brush and dried, and then cured for one week to obtain a test piece. 400 mL of water was put into a cylindrical aluminum alloy cup with a height of 75 mm and a diameter of 140 mm. The test piece was placed on the upper part of the cup with the coated surface facing up. The end of the test piece was sealed to prevent water vapor from escaping through the gap between the test piece and the cup, and it was left standing for 3 days. After standing, the weight of the entire container was measured, and this value was taken as the value before the test. After further standing for 7 days, the weight of the entire container was measured and taken as the value after the test. The value obtained by dividing the decrease in the weight of the entire container before and after the test by the number of test days was defined as the water vapor permeability (g / day). Those with a water vapor permeability (g / day) of 0.6 or more were evaluated as ○, indicating excellent water vapor permeability, and those with less than 0.6 were evaluated as ×, indicating insufficient water vapor permeability.

[0082] <Swelling resistance> Test pieces were prepared and tested by a method compliant with JIS A 6909. The aqueous coating composition for substrate adjustment of the examples and comparative examples was applied to the mortar (70×70×20 mm) specified in JISR 5201 at an application rate of 0.4 kg / m 2 by a roller brush, cured for 1 hour and dried. Then, the same aqueous coating composition for substrate adjustment was applied at an application rate of 0.4 kg / m 2 by a roller brush and dried to form a layer of the aqueous coating composition for substrate adjustment. Onto this, topcoat A was applied at an application rate of 0.35 kg / m 2 , or topcoat B was applied at an application rate of 0.15 kg / m 2 by a roller brush and dried for 5 hours or more. Then, topcoat A was applied again at an application rate of 0.35 kg / m 2 , or topcoat B was applied at an application rate of 0.15 kg / m 2 by a roller brush and dried. After drying, the four side surfaces of the mortar were sealed with a paste-like epoxy resin and cured for 14 days to obtain test pieces. The test pieces were subjected to 10 cycles of the cycle of "immersion in water at 23°C for 18 hours → -20°C for 3 hours → 50°C for 3 hours", and the state of the coating film surface was observed visually. Those without swelling were evaluated as ○, those with slight swelling were evaluated as △, and the others were evaluated as ×.

[0083] <Zero-span tensile elongation> Use a flexible board (100×100 mm, thickness 10 mm) specified in JISA 5430 as the base. Butt the short sides of two such bases against each other, and temporarily fix their back surfaces with curing tape. Apply the aqueous coating composition for base adjustment of the examples and comparative examples on the base surface at an application rate of 0.4 kg / m 2 using a roller brush, cure for 1 hour and dry. Then, apply the same aqueous coating composition for base adjustment at an application rate of 0.4 kg / m 2 using a roller brush, dry for 4 hours or more to form an aqueous coating composition layer for base adjustment. Apply topcoat A thereon at an application rate of 0.35 kg / m 2 or topcoat B at an application rate of 0.15 kg / m 2 using a roller brush, dry for 5 hours or more. Then, apply topcoat A again at an application rate of 0.35 kg / m 2 or topcoat B at an application rate of 0.15 kg / m 2 using a roller brush, cure for 14 days to obtain test specimens. Remove the temporary fixing curing tape on the back surface of the test specimens. Using a universal testing machine (manufactured by Instron), pull both ends of the test specimens at 2 mm / min. Evaluate those with a distance of 0.5 mm or more when pinholes occur in the coating film at the butted part as ○, and those with a distance less than 0.5 mm as ×.

Claims

1. A crosslinked acrylic resin emulsion having a glass transition temperature of -20 to 10°C, an acrylic resin containing one or more silica particles having a primary particle diameter of 15 to 30 nm, and a micelle having a particle diameter of 60 to 120 nm formed by an emulsifier dispersed in water, a water-soluble cationized polymer, a volatile base having a boiling point of 100°C or lower, a filler, an organic thickener, a film-forming aid, and a pigment, and the weight ratio of the solid content of the crosslinked acrylic resin emulsion to the solid content of the nanocomposite emulsion is 4 to 15:1, the silica particles are 10 to 20 parts by weight per 100 parts by weight of the nanocomposite emulsion, the blending amount of the water-soluble cationized polymer is 0.2 to 1.2 parts by weight per 100 parts by weight of the whole composition, the pH of the whole composition is 9.5 to 11.5, A water-based coating composition for substrate conditioning, characterized by the above.

2. The water-based coating composition for substrate conditioning according to Claim 1, wherein the water-soluble cationized polymer is a polyalkyleneimine compound.

3. The volatile base is ammonia, a lower alkylamine having C １ -C ４ The aqueous coating composition for substrate conditioning according to claim 1 or claim 2, characterized in that it consists of any one or a mixture of two or more of these, and dimethylaminomethanol.

4. The water-based coating composition for substrate conditioning according to any one of Claims 1 to 3, wherein the organic thickener is a urethane-modified polyether having a weight average molecular weight (Mw) of 10,000 to 35,000.

5. The viscosity of the composition is 60 to 150 Pa·s / 23°C at 2 rpm of a BH-type viscometer, and the TI value of the composition obtained by dividing the viscosity of the composition at 2 rpm of the BH-type viscometer by the viscosity at 20 rpm is 4 to 7. The water-based coating composition for substrate conditioning according to any one of Claims 1 to 4.

6. A substrate conditioning method, characterized by coating the water-based coating composition for substrate conditioning according to any one of Claims 1 to 5 on the substrate at least twice with a coating thickness of 0.15 to 0.5 mm.

7. A coating finish structure, characterized by comprising a water-based coating composition layer for substrate conditioning formed by coating the water-based coating composition for substrate conditioning according to any one of Claims 1 to 5, and a topcoat layer formed by coating a topcoat material on the water-based coating composition layer for substrate conditioning at least once.

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