Aqueous coating composition for two-component urethane coating film waterproofing material

Abstract

To provide an aqueous coating composition for a two-component urethane coating waterproofing material, which offers extended workability time while achieving both storage stability and usability.SOLUTION: There is provided a coating composition comprising (a) an acrylic emulsion, (b) a polyurethane dispersion, and (c) a pigment. The glass transition temperature of the (a) component is between 0 and 50°C. The solid content mass ratio of the (a) component to the (b) component is 80 / 20 to 20 / 80. The (a) component is present in a first liquid and / or a second liquid, the (b) component is present in the first liquid and / or the second liquid, and the (c) component is present only in the first liquid. The viscosity of the first liquid, measured using a type B viscometer, is between 1,000 and 10,000 mPa s under conditions of 20 rpm of rotational speed and a liquid temperature of 25°C. At a liquid temperature of 25°C, the Ti value, expressed as the viscosity of the first liquid at a rotational speed of 2 rpm divided by the viscosity of the same at a rotational speed of 20 rpm for the first liquid, is between 1.5 and 6.0. The viscosity of the mixture of the first liquid and the second liquid is 2,000 mPa s or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a water-based coating composition for a two-component urethane coating waterproofing material. [Background technology]

[0002] BACKGROUND ART Conventionally, a coating waterproofing method has been widely used as a waterproofing construction method for rooftops, verandas, balconies, open corridors, and the like of buildings. In this construction method, a multi-layer waterproof structure is typically created by forming a primer layer on the surface of a substrate such as concrete or mortar, then forming a urethane-based waterproofing material layer on top of that, and then forming a top coat layer on top of that.

[0003] In this case, the top coat is applied for the purpose of protecting the urethane-based waterproofing material layer and improving its appearance, and conventionally, acrylic urethane cross-linked two-component top coat compositions (see Patent Document 1) and room temperature drying one-component top coat compositions (see Patent Document 2) have been widely used.

[0004] However, the two-component top coat composition described in Patent Document 1 has the problem that it thickens within the usable time after mixing, resulting in poor workability. On the other hand, the one-component top coat composition described in Patent Document 2 has a trade-off between storage stability and workability, and when workability is prioritized, the viscosity is designed to be low, which leads to problems such as pigment settling. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-146268 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-112782 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in view of the above circumstances, and aims to provide an aqueous coating composition for a two-component urethane coating film waterproofing material that has a long pot life and is capable of achieving both storage stability and workability. [Means for solving the problem]

[0007] As a result of extensive research into achieving the above-mentioned object, the inventors have discovered that in an aqueous paint composition for a two-component urethane coating waterproofing material containing an acrylic emulsion, a polyurethane dispersion, and a pigment, by using an acrylic emulsion having a glass transition temperature within a predetermined range and adjusting the viscosity of the first component and the viscosity when the first component and the second component are mixed within a predetermined range, a paint composition can be obtained that has a long pot life and is capable of achieving both storage stability and workability, and have completed the present invention.

[0008] That is, the present invention is 1. (a) acrylic emulsion, (b) a polyurethane dispersion, and (c) Pigments Contains The glass transition temperature of the component (a) is 0 to 50°C, the solid content mass ratio of the component (a) to the component (b) is 80 / 20 to 20 / 80; The component (a) is present in the first liquid and / or the second liquid, The component (b) is present in the first liquid and / or the second liquid, The component (c) is present only in the first liquid, the viscosity of the first liquid measured by a Brookfield viscometer is 1,000 to 10,000 mPa s under conditions of a rotation speed of 20 rpm and a liquid temperature of 25°C, and the Ti value, expressed as the viscosity of the first liquid at a rotation speed of 2 rpm / the viscosity at a rotation speed of 20 rpm at a liquid temperature of 25°C, is 1.5 to 6.0; a water-based coating composition for a two-component urethane coating film waterproofing material, characterized in that the viscosity of a mixture of the first and second components is 2,000 mPa·s or less under conditions of a rotation speed of 20 rpm and a component temperature of 25°C; 2. The two-component aqueous coating composition for a urethane coating waterproofing material according to 1, wherein the solid content mass ratio of the component (a) to the component (b) is 75 / 25 to 25 / 75. 3. The two-component aqueous coating composition for a urethane coating film waterproofing material according to 1, wherein the viscosity of the first component measured with a Brookfield viscometer is 1,200 to 9,000 mPa·s and the Ti value is 1.5 to 6.0. 4. The two-component aqueous coating composition for urethane coating waterproofing material according to 1, wherein the viscosity of the mixture of the first and second components is 1 to 1,000 mPa·s. 5. The two-component aqueous coating composition for urethane coating film waterproofing material of 1, wherein the component (a) is an emulsion of a copolymer of alkyl methacrylate, alkyl acrylate, and acrylic acid. 6. The two-component aqueous coating composition for urethane coating waterproofing material of 1, wherein the component (b) is a dispersion of a reaction product of a urethane prepolymer obtained from a polyether polyol, an aliphatic or alicyclic diisocyanate, and a polyhydroxycarboxylic acid with a chain extender, dispersed in a mixed solvent of water and an organic solvent. to provide. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a two-component aqueous coating composition for a urethane coating film waterproofing material, which has a long pot life and is capable of achieving both storage stability and workability. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described in more detail below. The aqueous coating composition for a two-component urethane coating waterproofing material according to the present invention contains (a) an acrylic emulsion, (b) a polyurethane dispersion, and (c) a pigment, and is characterized in that the glass transition temperature of component (a) is 0 to 50°C, the solids mass ratio of components (a) and (b) is 80 / 20 to 20 / 80, component (a) is present in the first and / or second liquids, component (b) is present in the first and / or second liquids, and component (c) is present only in the first liquid, the viscosity of the first liquid measured with a Brookfield viscometer at a rotation speed of 20 rpm and a coating temperature of 25°C is 1,000 to 10,000 mPa·s or less, the Ti value, expressed as the viscosity of the first liquid at a rotation speed of 2 rpm / the viscosity at a rotation speed of 20 rpm at a coating temperature of 25°C, is 1.5 to 6.0 or less, and the viscosity of the mixture of the first and second liquids is 2,000 mPa·s or less.

[0011] (1)(a) Component The acrylic emulsion of component (a) is a component that improves the crack resistance of the coating film, and can be appropriately selected from, for example, aqueous solutions of known acrylic copolymers obtained by emulsion polymerization of acrylic monomers. In the present invention, however, it is necessary to adjust the monomer ratio during polymerization so that the glass transition temperature, calculated by the FOX equation, is 0 to 50°C, preferably 1 to 49°C.

[0012] Specific examples of acrylic monomers include alkyl acrylates such as methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate; alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, and lauryl methacrylate; acrylic acid, methacrylic acid; alkyl (meth)acrylates having a hydroxyl group such as 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, 2-hydroxyethyl acrylate, and hydroxypropyl acrylate; and (meth)acrylates having an epoxy group such as glycidyl methacrylate. These may be used alone or in combination of two or more.

[0013] Among these, it is preferable to use a combination of a monomer having excellent weather resistance, such as methyl methacrylate, ethyl methacrylate, cyclohexyl methacrylate, or methacrylic acid, and a monomer that can contribute to adhesion, such as n-butyl acrylate, hydroxyethyl methacrylate, or acrylic acid. In particular, in the present invention, it is more preferable to use a combination of alkyl methacrylate, alkyl acrylate, and acrylic acid in a ratio (mass ratio) that gives a glass transition temperature of 0 to 50°C according to the FOX equation.

[0014] The acrylic copolymer may be a copolymer of the acrylic monomer and another monomer, as long as the glass transition temperature is within the range mentioned above. Specific examples of other monomers include styrene, vinyl toluene, vinyl acetate, acrylonitrile, acrylamide, N-methylolacrylamide, diacetone acrylamide, maleic acid, and itaconic acid.

[0015] The acrylic emulsion can be produced by a known method, for example, by emulsifying a monomer such as the above-mentioned acrylic monomer in water with an emulsifier, and then emulsion-polymerizing the resulting emulsion in the presence of a polymerization initiator. As the water, it is preferable to use deionized water or pure water. The emulsifier can be appropriately selected from known anionic surfactants, cationic surfactants, and nonionic surfactants. Specific examples of the initiator include potassium peroxodisulfate, ammonium peroxodisulfate, sodium persulfate, and hydrogen peroxide. The reaction temperature is usually about 60 to 150° C. The reaction time is usually about 1 to 12 hours.

[0016] (2)(b) Component The urethane dispersion of component (b) is a component that increases the crack resistance of the coating film when it dries and also imparts elasticity to the coating film, and can be obtained, for example, by reacting a polyol, a diisocyanate, and a polyhydroxycarboxylic acid.

[0017] As the polyol, it is preferable to use a polyether polyol in consideration of the adhesion, extensibility, stain resistance, alkali resistance, acid resistance, abrasion resistance, etc. of the coating film. Specific examples of polyether polyols include homopolymers, block copolymers, and random copolymers of polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like. The weight average molecular weight (Mw) of the polyether polyol is not particularly limited, but is preferably 400 to 5,000, more preferably 700 to 3,000, from the viewpoint of the hydrolysis resistance of the coating material and the ability of the waterproofing material to follow the elongation.

[0018] As the diisocyanate, a non-yellowing type aliphatic or alicyclic diisocyanate is preferred, and specific examples thereof include hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, lysine diisocyanate, isopropylidenebis(4-cyclohexylisocyanate), hydrogenated xylylene diisocyanate, and dicyclohexyl diisocyanate. Of these, hexamethylene diisocyanate, isophorone diisocyanate, and hydrogenated xylylene diisocyanate are preferred.

[0019] Polyhydroxycarboxylic acids are components that are introduced to improve the dispersibility of polyurethane in water, and specific examples thereof include dimethylolpropionic acid, dimethylolbutanoic acid, 2,2-dimethylolbutyric acid, and 2,2-dimethylolvaleric acid. Among these, dimethylolpropionic acid and dimethylolbutanoic acid are preferred in consideration of compatibility with the acrylic copolymer.

[0020] Urethane dispersions can be obtained, for example, by reacting a polyol, a diisocyanate, and a polyhydroxycarboxylic acid in an organic solvent to produce a prepolymer, adding a neutralizing agent and a chain extender to the resulting prepolymer as appropriate, and then adding deionized water or pure water. The organic solvent is preferably one that is inert to isocyanate groups and has high affinity for water, and examples thereof include glycol ether solvents such as diethylene glycol dimethyl ether; cyclic ether solvents such as dioxane and tetrahydrofuran; ketone solvents such as acetone and methyl ethyl ketone; and cyclic amide solvents such as N-methylpyrrolidone.

[0021] Specific examples of chain extenders include polyols such as ethylene glycol and propylene glycol; aliphatic, alicyclic, and aromatic diamines such as ethylenediamine, propylenediamine, hexamethylenediamine, tolylenediamine, xylylenediamine, diphenyldiamine, diaminodiphenylmethane, diaminocyclohexylmethane, piperazine, 2-methylpiperazine, and isophoronediamine; and water. Specific examples of the neutralizing agent include amines such as trimethylamine, triethylamine, tri-n-propylamine, tributylamine, and triethanolamine; sodium hydroxide, potassium hydroxide, and ammonia.

[0022] The reaction temperature during production of the prepolymer is usually about 60 to 150° C. The reaction time is usually about 1 to 12 hours. The reaction temperature between the prepolymer and the chain extender is usually about 20 to 100° C. The reaction time is usually about 0.1 to 5 hours. The solid content of the urethane dispersion is preferably from 20 to 60% by mass, more preferably from 25 to 40% by mass.

[0023] (3)(c) component The pigment of component (c) is not particularly limited, and can be appropriately selected from conventionally known color pigments, extender pigments, and the like. Examples of color pigments include inorganic pigments such as titanium oxide, zinc oxide, carbon black, ferric oxide (red iron oxide), yellow lead, yellow iron oxide, ochre, ultramarine, and cobalt green; and organic pigments such as azo pigments, naphthol pigments, pyrazolone pigments, anthraquinone pigments, perylene pigments, quinacridone pigments, disazo pigments, isoindolinone pigments, benzimidazole pigments, phthalocyanine pigments, and quinophthalone pigments. Examples of extender pigments include heavy calcium carbonate, clay, kaolin, talc, precipitated barium sulfate, barium carbonate, white carbon, and diatomaceous earth.

[0024] In the two-component aqueous coating composition for a urethane coating film waterproofing material of the present invention, the blending ratio of the above-mentioned components (a) and (b) is preferably 80 / 20 to 20 / 80, more preferably 75 / 25 to 25 / 75, in terms of solid mass ratio. The blending ratio of component (c) is about 1 to 1,000 parts by mass, and preferably about 40 to 500 parts by mass, per 100 parts by mass of the solid content of component (a).

[0025] In the aqueous coating composition for two-component urethane coating film waterproofing materials of the present invention, each component may be present in either the first or second liquid. However, in consideration of extending the usable life of the coating composition and achieving both storage stability and workability, it is preferable that component (a) be present in the first and / or second liquid, component (b) be present in the first and / or second liquid, and component (c) be present only in the first liquid, and it is even more preferable that components (a) and (c) be present only in the first liquid, and component (b) be present only in the second liquid.

[0026] Furthermore, taking into consideration workability and the like, the viscosity of the first liquid as measured by a Brookfield viscometer at a rotation speed of 20 rpm and a temperature of 25°C is preferably 1,000 to 10,000 mPa·s, more preferably 1,200 to 9,000 mPa·s, and even more preferably 1,500 to 8,500 mPa·s, and the Ti value, expressed as the viscosity of the first liquid at a rotation speed of 2 rpm / the viscosity at a rotation speed of 20 rpm under the same temperature of 25°C, is preferably 1.5 to 6.0, more preferably 2.0 to 5.0, and even more preferably 2.1 to 4.5.

[0027] Furthermore, in order to extend the usable time and achieve both storage stability and workability, the viscosity of the coating composition obtained by mixing the first and second liquids is preferably 2,000 mPa·s or less, more preferably 1,000 mPa·s or less, and even more preferably 500 mPa·s or less, at a rotation speed of 20 rpm and a liquid temperature of 25°C. There is no particular restriction on the lower limit of the viscosity, but it is preferably 1 mPa·s or more, and more preferably 10 mPa·s or more.

[0028] The aqueous coating composition for two-component urethane coating film waterproofing materials of the present invention may contain 0.1 to 30 mass % of various additives such as viscosity adjusters, plasticizers, preservatives, mildew inhibitors, anti-algae agents, antifoaming agents, leveling agents, pigment dispersants, anti-settling agents, anti-sagging agents, matting agents, UV absorbers, thickeners, light stabilizers, and catalysts, as long as the effects of the present invention are not impaired. These additives may be blended into either the first liquid or the second liquid, or into both, but are preferably blended into the first liquid.

[0029] The two-component aqueous coating composition for urethane coating film waterproofing materials of the present invention can be suitably used as a two-component room temperature curing composition in which the two components are mixed on-site and applied. In this case, the application method is not particularly limited and may be appropriately selected from known methods such as brush application, roller application, etc. The amount of application, thickness of the coating film, drying time, etc. may be appropriately set depending on the type of urethane waterproofing material, etc. [Example]

[0030] The present invention will be specifically described below with reference to Synthesis Examples, Comparative Synthesis Examples, Examples, and Comparative Examples, but the present invention is not limited to the following Examples. In the following, "parts" means "parts by mass" and "%" means "% by mass."

[0031] [Synthesis Example 1] Synthesis of acrylic emulsion a-1 A reactor equipped with a stirrer, reflux condenser, thermometer, dropping device, and nitrogen inlet tube was charged with 45.0 parts of deionized water and 1.0 part of the reactive anionic surfactant Aqualon KH-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.). The atmosphere inside the reactor was replaced with nitrogen and the temperature was raised to 80°C. A mixture of 46.0 parts of methyl methacrylate, 52.0 parts of butyl acrylate, 2.0 parts of acrylic acid, 60.0 parts of deionized water, 2.5 parts of Aqualon KH-10, and 0.5 parts of potassium peroxodisulfate, which had been mixed and stirred in a separate container, was then added dropwise over 3 hours. The mixture was then aged at 80°C for 2 hours with continued stirring, cooled to room temperature, and the pH was adjusted to 8.0 with dimethylaminoethanol to obtain an acrylic emulsion.

[0032] [Synthesis Examples 2 and 3 and Comparative Synthesis Examples 1 and 2] Acrylic emulsions a-2 to a-5 were obtained in the same manner as in Synthesis Example 1, except that the composition of each component was changed to the allocation shown in Table 1. The glass transition temperatures of the acrylic emulsions shown in Table 1 are values ​​calculated using the FOX formula.

[0033] [Table 1]

[0034] [Synthesis Example 4] Synthesis of urethane dispersion b-1 A reactor equipped with a stirrer, cooling tube, nitrogen inlet tube, and thermometer was charged with 21.0 parts of isophorone diisocyanate, 74.0 parts of Sannix PP-3000 (polypropylene glycol, manufactured by Sanyo Chemical Industries, Ltd.), 5.0 parts of dimethylolpropionic acid, and 60.0 parts of diethylene glycol dimethyl ether under a nitrogen atmosphere at 80°C for 3.0 hours to obtain an NCO-terminated prepolymer solution. The resulting prepolymer solution was cooled to 40°C, and 3.8 parts of triethylamine was added for neutralization. The neutralized prepolymer solution was then dispersed in 150.0 parts of deionized water to obtain a prepolymer dispersion. A solution containing 3.2 parts of N-(2-aminoethyl)ethanolamine in 27.0 parts of deionized water was added to the prepolymer dispersion and stirred at 30°C for 1 hour to obtain polyurethane dispersion b-1 with a solids content of 30.0%.

[0035] [Table 2]

[0036] [1] Preparation of aqueous coating composition [Example 1] To 40.0 parts of water, 80.0 parts of titanium dioxide (TIPAQUE PFC-105, manufactured by Ishihara Sangyo Kaisha), 4.0 parts of pigment dispersant (DISPERBYK-190, manufactured by BYK Japan Co., Ltd.), and 1.0 part of defoamer (SN DEFOAMER 1311, manufactured by San Nopco Co., Ltd.) were added, and 126 parts of glass beads were added. The mixture was dispersed for 1 hour using a paint shaker. After removing the glass beads, 280.0 parts of the acrylic emulsion a-1 obtained in Synthesis Example 1 was added to the resulting dispersion. 60.0 parts of water, 30.0 parts of a film-forming aid (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate), 2.0 parts of a defoamer (SN DEFOAMER 1311), and 3.0 parts of a viscosity modifier (ADEKA NOL UH-420, manufactured by ADEKA Corporation) were added and further stirred to prepare the first liquid of aqueous coating composition P-1. Separately, 470.0 parts of the urethane dispersion b-1 obtained in Synthesis Example 4 was added to 30.0 parts of water and stirred to prepare the second liquid of aqueous coating composition P-1.

[0037] [Examples 2 to 8, Comparative Examples 1 to 8] The first and second liquids of the aqueous coating composition were prepared in the same manner as in Example 1, except that the compositions were changed to those shown in Tables 3 and 4 below. The components in Tables 3 and 4 are as follows: [Component (a)] a-1 to a-5: Acrylic emulsions obtained in the above Synthesis Examples 1 to 4 and Comparative Synthesis Examples 1 and 2 [(b) component] b-1: Urethane dispersion obtained in Synthesis Example 4 above [(c) component] TIPAQUE PFC-105: Titanium oxide, manufactured by Ishihara Sangyo Kaisha, Ltd. [Viscosity adjuster] ADEKA NOL UH-420: Special non-ionic polymer surfactant, manufactured by ADEKA Corporation ADEKA NOL UH-438: Special non-ionic polymer surfactant, manufactured by ADEKA Corporation ADEKA NOL UH-752: Special nonionic polymer surfactant, manufactured by ADEKA Corporation [Dispersant] DISPERBYK-190: Block copolymer, manufactured by BYK Japan Co., Ltd. [Antifoaming agent] SN Deformer 1311: Silicone defoamer, manufactured by San Nopco Ltd.

[0038] [Table 3]

[0039] [Table 4]

[0040] [2] Evaluation of water-based paint compositions The aqueous coating compositions prepared in the above Examples and Comparative Examples were evaluated as follows, and the results are shown in Table 5. (1) Storage stability The aqueous coating compositions obtained in the Examples and Comparative Examples were poured into 250 mL containers up to three-quarters of the capacity, the containers were sealed, and the containers were left to stand at 35°C for 30 days. After the specified time, the containers were opened, and the state inside the containers was checked using a spatula and evaluated according to the following criteria. <Evaluation criteria> ○: No abnormalities were observed. ×: Caking is observed at the bottom of the container. (2) Application efficiency when using a roller Two-component room temperature curing urethane waterproofing coating material was applied to the surface of release paper (30cm x 30cm) at 2kg / m 2 The coating was then left to cure for 24 hours under conditions of 23°C and 50% RH. 2 The coating was applied using a medium-pile roller at a ratio of 100% and then cured for 24 hours at 23°C and 50% RH. The workability of the roller coating was evaluated according to the following criteria. <Evaluation criteria> ○: There is no problem with workability and no roller marks are observed. ×: Poor workability, roller marks observed. (3) Stretchability The coating film prepared in (2) above was peeled from the release paper and punched out using a No. 2 dumbbell to prepare a test specimen. The extensibility was evaluated using a tensile tester (Shimadzu Corporation, Autograph AG-5000C) at a pulling rate of 200 mm / min to measure the elongation rate until the test specimen broke, and was rated on the following three-point scale. <Evaluation criteria> ○: Elongation rate 100% or more △: Elongation rate 50% or more but less than 100% ×: Elongation rate less than 50% (4) Accelerated weather resistance The accelerated weathering test was carried out using an ultra-accelerated weathering tester (Iwasaki Electric Co., Ltd., Eye Super UV Tester). Test specimens were prepared by peeling the coating film prepared in (2) above from the release paper and cutting it into 50 x 50 x 4 mm. The test conditions were: wavelength 295 to 450 nm, ultraviolet irradiation intensity 100 mW / cm 2 The test was conducted for 75 cycles (600 hours) at a black panel temperature of 63°C and 50% RH, with one cycle consisting of 4 hours of irradiation and 4 hours of condensation. After the test, the gloss retention rate of the coating film relative to the initial 60-degree specular gloss value was calculated and rated on the following three scales. <Evaluation criteria> ○: Gloss retention rate 70% or more △: Gloss retention rate is 50% or more but less than 70% ×: Gloss retention rate less than 50%

[0041] [Table 5]

Claims

1. (a) an acrylic emulsion; (b) a polyurethane dispersion, and (c) Pigment Contains The glass transition temperature of the component (a) is 0 to 50°C, the solid content mass ratio of the component (a) to the component (b) is 80 / 20 to 20 / 80; The component (a) is present in the first liquid and / or the second liquid, The component (b) is present in the first liquid and / or the second liquid, The component (c) is present only in the first liquid, the viscosity of the first liquid measured by a Brookfield viscometer at a rotation speed of 20 rpm and a liquid temperature of 25°C is 1,000 to 10,000 mPa s, and the Ti value, expressed as the viscosity of the first liquid at a rotation speed of 2 rpm / the viscosity at a rotation speed of 20 rpm at a liquid temperature of 25°C, is 1.5 to 6.0; A two-component aqueous coating composition for urethane coating waterproofing, characterized in that the viscosity of the mixture of the first and second liquids is 2,000 mPa·s or less under conditions of a rotation speed of 20 rpm and a liquid temperature of 25°C.

2. 2. The aqueous coating composition for a two-component urethane coating film waterproofing material according to claim 1, wherein the mass ratio of solid content of said component (a) to said component (b) is 75 / 25 to 25 / 75.

3. 2. The aqueous coating composition for a two-component urethane coating film waterproofing material according to claim 1, wherein the viscosity of the first component measured by a Brookfield viscometer is 1,200 to 9,000 mPa·s, and the Ti value is 1.5 to 6.

0.

4. 2. The aqueous coating composition for a two-component urethane coating waterproofing material according to claim 1, wherein the viscosity of the mixture of the first and second components is 1 to 1,000 mPa·s.

5. 2. The two-component aqueous coating composition for a urethane coating film waterproofing material according to claim 1, wherein said component (a) is an emulsion of a copolymer of alkyl methacrylate, alkyl acrylate and acrylic acid.

6. 2. The aqueous coating composition for a two-component urethane coating waterproofing material according to claim 1, wherein component (b) is a dispersion in a mixed solvent of water and an organic solvent of a reaction product of a urethane prepolymer obtained from a polyether polyol, an aliphatic or alicyclic diisocyanate, and a polyhydroxycarboxylic acid with a chain extender.

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