Water-based components

Abstract

Even when containing an epoxy resin containing a cardanol skeleton, an aqueous composition with excellent adhesion of the coating film can be provided. [Solution] An aqueous composition containing an epoxy resin containing a cardanol skeleton, a neutralized product of an acid group-containing acrylic resin, a surfactant, and water, wherein the neutralized product of the acid group-containing acrylic resin satisfies the following conditions (A) and / or (B). (A) The above-mentioned acid group-containing acrylic resin includes an acid group-containing acrylic resin having a glass transition temperature of 100°C or lower. (B) The above acid group-containing acrylic resin includes an acid group-containing acrylic resin having a glass transition temperature of over 100°C, and the variable X in the following formula (I) is 0.60 or less. X = Mass of solids of acid-containing acrylic resin with a glass transition temperature exceeding 100°C contained in the aqueous composition / (Mass of solids of acid-containing acrylic resin with a glass transition temperature exceeding 100°C contained in the aqueous composition + Mass of solids of surfactant contained in the aqueous composition) ... (I)

Description

[Technical Field]

[0001] This invention relates to an aqueous composition. [Background technology]

[0002] Water-based epoxy resin emulsions are used as binder resins in paints and other applications, and various types are publicly known.

[0003] In recent years, there has been a growing demand for biomass-based epoxy resins.

[0004] For example, Patent Document 1 discloses a low-VOC aqueous dispersion containing an epoxy resin with a cardanol skeleton, water, and a surfactant as a biomass-derived epoxy resin. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Special Publication No. 2016-506980 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, there were issues with the adhesion of coating films obtained from aqueous dispersions using epoxy resins containing a cardanol skeleton as described in Patent Document 1.

[0007] Therefore, the present invention aims to provide an aqueous composition that exhibits excellent adhesion of the coating film, even when containing an epoxy resin containing a cardanol skeleton. [Means for solving the problem]

[0008] As a result of diligent research by the present inventors, we have discovered that in an aqueous dispersion system of an epoxy resin containing a cardanol skeleton, comprising an epoxy resin containing a cardanol skeleton, a neutralized acid group-containing acrylic resin, a surfactant, and water, by using an acid group-containing acrylic resin with a glass transition temperature within a specific range as the neutralized acid group-containing acrylic resin, an aqueous composition with excellent adhesion of the coating film can be obtained, thus completing the present invention.

[0009] The present invention relates to an aqueous composition containing an epoxy resin containing a cardanol skeleton, a neutralized product of an acid group-containing acrylic resin, a surfactant, and water, wherein the neutralized product of the acid group-containing acrylic resin satisfies the following conditions (A) and / or (B). (A) The above-mentioned acid group-containing acrylic resin includes an acid group-containing acrylic resin having a glass transition temperature of 100°C or lower. (B) The above acid group-containing acrylic resin includes an acid group-containing acrylic resin having a glass transition temperature of over 100°C, and the variable X in the following formula (I) is 0.60 or less. X = Mass of solids of acid-containing acrylic resin with a glass transition temperature exceeding 100°C contained in the aqueous composition / (Mass of solids of acid-containing acrylic resin with a glass transition temperature exceeding 100°C contained in the aqueous composition + Mass of solids of surfactant contained in the aqueous composition) ... (I)

[0010] In the aqueous composition of the present invention, the epoxy resin preferably contains a polymerized cardanol skeleton. Furthermore, it is preferable that the epoxy resin contains a bisphenol skeleton. Furthermore, the above-mentioned acid group-containing acrylic resin preferably has a weight-average molecular weight of 5000 or more. Furthermore, the above-mentioned acid group-containing acrylic resin preferably has an acid value of 50 mgKOH / g or higher. Furthermore, it is preferable that the above-mentioned surfactant has an HLB value of 15 or higher. Furthermore, it is preferable that the above-mentioned surfactant is at least one selected from the group consisting of polyalkylene oxide-based surfactants, polyoxyalkylene alkyl ether-based surfactants, and acetylene glycol-based surfactants. [Effects of the Invention]

[0011] The present invention provides an aqueous composition that exhibits excellent adhesion of the coating film, even when containing an epoxy resin containing a cardanol skeleton. [Modes for carrying out the invention]

[0012] <Aqueous composition> The aqueous composition of the present invention contains an epoxy resin containing a cardanol skeleton, a neutralized product of an acid group-containing acrylic resin, a surfactant, and water, wherein the neutralized product of the acid group-containing acrylic resin satisfies the following conditions (A) and / or (B). (A) The above-mentioned acid group-containing acrylic resin includes an acid group-containing acrylic resin having a glass transition temperature of 100°C or lower. (B) The above acid group-containing acrylic resin includes an acid group-containing acrylic resin having a glass transition temperature of over 100°C, and the variable X in the following formula (I) is 0.60 or less. X = Mass of solids of acid-containing acrylic resin with a glass transition temperature exceeding 100°C contained in the aqueous composition / (Mass of solids of acid-containing acrylic resin with a glass transition temperature exceeding 100°C contained in the aqueous composition + Mass of solids of surfactant contained in the aqueous composition) ... (I)

[0013] (Epoxy resin containing a cardanol skeleton) The aqueous composition of the present invention contains an epoxy resin containing a cardanol skeleton.

[0014] An epoxy resin containing the above-mentioned cardanol skeleton can be obtained by a reaction between an epoxy resin and cardanol.

[0015] The epoxy resin described above preferably contains a bisphenol skeleton. The bisphenol skeleton may be bisphenol A type, bisphenol S type, or bisphenol F type, but bisphenol A type is preferred.

[0016] Examples of commercially available products of the above epoxy resin include jER-828 (manufactured by Mitsubishi Chemical Corporation), Epomic-R140 (manufactured by Mitsui Chemicals, Inc.), EP-4100 (manufactured by ADEKA Corporation), YD-128 (manufactured by Nippon Steel Chemical & Material Co., Ltd.), D.E.R.331, D.E.R.354, D.E.R.332, D.E.R.330, D.E.R.383 (all manufactured by Dow Chemical Company), etc.

[0017] The above cardanol is a component derived from cashew nut shell liquid and has, for example, the structure of the following formula (1).

Chemical formula

[0018] The epoxy resin containing the above cardanol skeleton may be modified. For example, a part of the epoxy group may be acrylate-modified or urethane-modified.

[0019] Examples of the method for producing the epoxy resin containing the above cardanol skeleton include, for example, the following method. React the above cardanol in the presence of an acid catalyst to form a polymer (Reaction 1). Next, react the obtained polymer with the above epoxy resin under basic conditions (Reaction 2). If necessary, modify the obtained epoxy resin containing the cardanol skeleton (Reaction 3).

[0020] As the acid catalyst used in reaction 1 above, known ones can be used, for example, inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid, or organic acids such as acetic acid, citric acid, propionic acid, oxalic acid, and p-toluenesulfonic acid. In particular, from the viewpoint of catalytic activity and solubility in solution, it is preferable to use p-toluenesulfonic acid. The amount of the above-mentioned acid catalyst used is approximately 0.1 to 4 parts by mass per 100 parts by mass of cardanol.

[0021] The polymer obtained in reaction 1 above is preferably a 2-20-mer of cardanol. The above polymer forms a polymerized cardanol skeleton in an epoxy resin containing the desired cardanol skeleton.

[0022] The reaction temperature for reaction 1 described above is, for example, around 80 to 180°C. The reaction time is, for example, around 1 to 10 hours. Furthermore, the successful acquisition of the target polymer can be confirmed, for example, by using gel permeation chromatography (GPC) to observe a decrease in the peak derived from cardanol and the distillation of new components.

[0023] The apparatus used in reaction 1 above (stirring apparatus, reflux apparatus, etc.) can be appropriately selected from known equipment. After the above reaction, the product may be purified by a known method, or it may not be purified. Purification by a known method is more preferable.

[0024] In reaction 2 described above, it is preferable to react the polymer with the epoxy resin under basic conditions.

[0025] In reaction 2 described above, the mass ratio of the polymer to the epoxy resin is preferably 1:0.5 to 1.5.

[0026] The base used in reaction 2 above is not particularly limited, but examples include alkali metal hydrides, alkaline earth metal hydrides, alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal carbonates, alkaline earth metal carbonates, alkali metal bicarbonates, alkali metal alkoxides, alkaline earth metal alkoxides, alkali metal fluorides, amines, organophosphorus compounds, and the like. The amount of the above-mentioned base used varies depending on the type of base, but for example, it is about 0.1 to 2.0 parts by mass per 100 parts by mass of the polymer.

[0027] In reaction 2 described above, a solvent may be used if necessary. The above solvents are not particularly limited, but preferred examples include water, alcohols such as methanol, ethanol, and 2-propanol, aprotic polar solvents such as dimethyl sulfone, dimethyl sulfoxide, tetrahydrofuran, dioxane, methyl ethyl ketone, methyl isobutyl ketone, acetonitrile, methylene chloride, and dimethylformamide, aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as hexane, chloroform, and carbon tetrachloride, but are not limited to these. The above solvents may be used individually or in combination of multiple types. The amount of solvent used is, for example, about 30 parts by mass or less per 100 parts by mass of the polymer.

[0028] The reaction temperature for reaction 2 described above is, for example, around 60 to 120°C. The reaction time is, for example, around 1 to 10 hours. Furthermore, the target compound can be analyzed using, for example, gel permeation chromatography (GPC), to confirm the decrease in the peak originating from the raw material (e.g., the epoxy resin mentioned above) and the distillation of new components.

[0029] The apparatus used in reaction 2 above (stirring apparatus, reflux apparatus, etc.) can be appropriately selected from known sources. After the above reaction, the product may be purified by a known method, or it may not be purified. Purification by a known method is more preferable.

[0030] In reaction 3 described above, the epoxy groups of the epoxy resin containing the cardanol skeleton may be modified by acrylic, urethane, amine, phenol, carboxylic acid, etc., using known methods. For example, the epoxy groups of an epoxy resin containing a cardanol skeleton may be reacted with acrylic acid and / or methacrylic acid in the presence of a base catalyst, or with isocyanate compounds, polyamine resins, phenolic resins, or carboxylic acid compounds. The amount of acrylic acid and / or methacrylic acid, isocyanate compounds, polyamine resins, phenolic resins, and carboxylic acid compounds added can be appropriately adjusted according to the desired degree of modification.

[0031] The content (solids) of the epoxy resin containing the cardanol skeleton described above is preferably 30% by mass or more and 95% by mass or less, relative to the total solids of the aqueous composition.

[0032] (Neutralized product of acid-containing acrylic resin) The aqueous composition of the present invention contains a neutralized product of an acid group-containing acrylic resin. The neutralized product of the above acid group-containing acrylic resin satisfies the following conditions (A) and / or (B). (A) The above-mentioned acid group-containing acrylic resin includes an acid group-containing acrylic resin having a glass transition temperature of 100°C or lower. (B) The above acid group-containing acrylic resin includes an acid group-containing acrylic resin having a glass transition temperature of over 100°C, and the variable X in the following formula (I) is 0.60 or less. X = Mass of solids of acid-containing acrylic resin with a glass transition temperature exceeding 100°C contained in the aqueous composition / (Mass of solids of acid-containing acrylic resin with a glass transition temperature exceeding 100°C contained in the aqueous composition + Mass of solids of surfactant contained in the aqueous composition) ... (I)

[0033] The above (A) will be explained. Because the neutralized acid group-containing acrylic resin has a glass transition temperature of 100°C or lower, even if epoxy resins containing a cardanol skeleton or surfactants are included, the overall coating film has appropriate properties, making it possible to obtain a water-based resin with excellent coating adhesion.

[0034] If the above (A) is satisfied, the above acid group-containing acrylic resin preferably has a glass transition temperature of 90°C or lower, and more preferably 80°C or lower. Furthermore, if the above (A) is satisfied, the acid group-containing acrylic resin preferably has a glass transition temperature of 30°C or higher, and more preferably 50°C or higher. The "glass transition temperature" may be measured using a thermal analysis device such as a differential scanning calorimeter (DSC), but if Wood's equation can be applied, it is preferable to use the theoretical glass transition temperature obtained by Wood's equation.

[0035] The above (B) will be explained. Since the glass transition temperature of the above acid group-containing acrylic resin exceeds 100°C and the variable X in formula (I) is 0.60 or less, by using the above acid group-containing resin within a specific range, the overall coating film has appropriate properties, and thus an aqueous resin with excellent coating film adhesion can be obtained.

[0036] If the above condition (B) is met, the glass transition temperature is preferably 130°C or lower, and more preferably 120°C or lower. Furthermore, the above variable X is preferably 0.55 or less, and more preferably 0.5 or less.

[0037] The above-mentioned acid group-containing acrylic resin is preferably, from the viewpoint of storage stability of the aqueous composition of the present invention and the various resistances of the coating obtained from the aqueous composition of the present invention, has a weight-average molecular weight of 5000 or more, more preferably 10000 or more, even more preferably 12000 or more, and particularly preferably 14000 or more. In this specification, "weight-average molecular weight" refers to a value measured, for example, as a polystyrene equivalent by gel permeation chromatography (GPC).

[0038] From the viewpoint of storage stability of the aqueous composition of the present invention, the above acid group-containing acrylic resin is preferably such that the above acid value is 50 mg KOH / g or more, more preferably 120 mg KOH / g or more, and even more preferably 150 mg KOH / g or more. In this specification, "acid value" refers to the theoretical acid value obtained by arithmetically calculating the number of mg of potassium hydroxide theoretically required to neutralize 1 g of the unneutralized acid group-containing acrylic resin.

[0039] From the viewpoint of affinity with the epoxy resin, the above acid group-containing acrylic resin is preferably a styrene acrylic resin, and more preferably a styrene acrylic maleic acid resin.

[0040] The neutralized product of the acid group-containing acrylic resin described above is obtained by neutralizing the acid group-containing acrylic resin mentioned above. A base can be used to neutralize the above-mentioned acid group-containing acrylic resin. Examples of the above-mentioned bases include ammonia, organic amines such as dimethylethanolamine, and alkali metals such as sodium hydroxide and potassium hydroxide.

[0041] The neutralized product of the above acid group-containing acrylic resin preferably has a pH of 8 to 9. The above pH values ​​were measured in accordance with JIS Z8802:2011.

[0042] The content (solids) of the neutralized acid group-containing acrylic resin is preferably 5% by mass or more and 80% by mass or less, relative to the total solids of the aqueous composition. The content (solids) of the neutralized product of the above acid group-containing acrylic resin is preferably 5% by mass or more and 80% by mass or less, relative to the solids mass of the epoxy resin containing the cardanol skeleton.

[0043] (Surfactants) The aqueous composition of the present invention contains a surfactant.

[0044] As for the surfactant mentioned above, from the viewpoint of adhesion of the aqueous composition coating film, it is preferable that the HLB value is 10 or higher, and more preferably 15 or higher. In this specification, "HLB value" refers to the HLB value calculated using the Griffin method.

[0045] The surfactants mentioned above are not particularly limited as long as they satisfy the numerical range of the above HLB value, but examples include polyalkylene oxides, polyoxyalkylene alkyl ethers, acetylene glycols, and the like.

[0046] The amount of the surfactant is preferably 2% by mass or more and 10% by mass or less, based on the total mass of the aqueous composition.

[0047] (water) The aqueous composition of the present invention contains water.

[0048] For the water used, deionized water or purified water can be used.

[0049] The water content is preferably 30% by mass or more and 99% by mass or less, relative to the total mass of the aqueous composition.

[0050] (others) The aqueous composition of the present invention may optionally contain additives.

[0051] Examples of the above-mentioned additives include pH adjusters, preservatives / fungicides, rust inhibitors, chelating agents, viscosity modifiers, solubilizers, and antioxidants. The amount of each additive can be determined appropriately depending on the type of additive.

[0052] (Method for producing aqueous compositions) The method for producing the aqueous composition of the present invention is not particularly limited, and the various materials described above may be mixed by known methods. If the epoxy resin containing the cardanol skeleton is not a water-based resin, it can be emulsified and dispersed with an acid group-containing acrylic resin or surfactant. The above mixture may be heated, and if a solvent is used, it may be removed by distillation using a known method.

[0053] This specification discloses the following: (1) of this disclosure contains an epoxy resin containing a cardanol skeleton, a neutralized acid group-containing acrylic resin, a surfactant, and water, wherein the neutralized acid group-containing acrylic resin is an aqueous composition satisfying the following (A) and / or (B). (A) The above-mentioned acid group-containing acrylic resin includes an acid group-containing acrylic resin having a glass transition temperature of 100°C or lower. (B) The above acid group-containing acrylic resin includes an acid group-containing acrylic resin having a glass transition temperature of over 100°C, and the variable X in the following formula (I) is 0.60 or less. X = Mass of solids of acid-containing acrylic resin with a glass transition temperature exceeding 100°C contained in the aqueous composition / (Mass of solids of acid-containing acrylic resin with a glass transition temperature exceeding 100°C contained in the aqueous composition + Mass of solids of surfactant contained in the aqueous composition) ... (I) Disclosure (2) is an aqueous composition according to Disclosure (1) in which the epoxy resin contains a polymerized cardanol skeleton. Disclosure (3) is the aqueous composition according to Disclosure (1) or (2) wherein the epoxy resin contains a bisphenol skeleton. Disclosure (4) is an aqueous composition according to any one of Disclosures (1) to (3) wherein the acid group-containing acrylic resin has a weight-average molecular weight of 5000 or more. Disclosure (5) is an aqueous composition according to any one of Disclosures (1) to (4), wherein the acid group-containing acrylic resin is 50 mg KOH / g or more. Disclosure (6) is an aqueous composition according to any one of Disclosures (1) to (5) wherein the surfactant has an HLB value of 15 or more. Disclosure (7) is an aqueous composition according to any one of Disclosures (1) to (6), wherein the surfactant is at least one selected from the group consisting of polyalkylene oxides, polyoxyalkylene alkyl ethers, and acetylene glycols. [Examples]

[0054] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "%" means "mass%" and "parts" means "parts by mass".

[0055] <Preparation of resin varnish 1-5> The following materials were prepared as resin. Resin 1 (Styrene acrylic maleic acid resin, acid value 170 mg KOH / g, glass transition temperature 71°C, weight-average molecular weight 18000) Resin 2 (Product name "Joncryl JDX-5050", styrene-acrylic resin, acid value 190 mg KOH / g, glass transition temperature 115°C, weight-average molecular weight 14000, manufactured by BASF) Resin 3 (Acrylic resin, acid value 100 mg KOH / g, glass transition temperature 107°C, weight-average molecular weight 11000) Resin 4 (polymerized rosin, acid value 145mgKOH / g, weight average molecular weight 800) Resin 5 (Product name "Hyros-X AW-36H", acrylic resin, acid value 60 mg KOH / g, glass transition temperature 53°C, weight-average molecular weight 16000, solids content 25% by mass, manufactured by Seikoh PMC Co., Ltd.) The glass transition temperature, acid value, and weight-average molecular weight of the acid group-containing acrylic resin were determined by the method described herein.

[0056] Each resin was neutralized and converted to an aqueous solution using purified water and 25% ammonia water to prepare resin varnishes 1 to 5 with a resin solids content of 30% by mass and a pH of 8.0 to 9.0. Regarding resin 5, since its resin solids content was 25% by mass and its pH was in the range of 8.0 to 9.0, it was used as is as a resin varnish.

[0057] <Surfactants> Surfactant 1 (Product name "Newpol PE-128", ethylene oxide / propylene oxide block polymer, HLB value 15, manufactured by Sanyo Chemical Industries, Ltd.) Surfactant 2 (Product name "Sunnonic SS-70", polyoxyalkylene alkyl ether, HLB value 12.1, manufactured by Sanyo Chemical Industries, Ltd.) Surfactant 3 (Product name "Triton HW-1000", polyoxyethylene alkyl ether, HLB value 10, manufactured by Dow Chemical) Surfactant 4 (Product name "Emulgen A500", polyoxyethylene distyrenated phenyl ether, HLB value 18, manufactured by Kao Corporation) Surfactant 5 (Product name "Nikanol AM-2000", contains ethylene oxide adduct of xylene resin, HLB value 13.2, manufactured by Fudo Co., Ltd.)

[0058] <Preparation of epoxy resin solution containing cardanol skeleton> (Epoxy resin solution 1) In a flask equipped with a stirrer, reflux condenser, and stirring device, 100 parts by mass of purified cardanol were weighed out while purging with nitrogen, and 3.1 parts by mass of p-toluenesulfonic acid monohydrate were added to prepare the reaction solution. The reaction solution was then heated to 100°C and stirred for 4 hours. 25 parts by mass of an aqueous sodium hydroxide solution (1.3 parts by mass of sodium hydroxide dissolved in 23.7 parts by mass of deionized water) was added to the reaction solution, and the mixture was stirred for 30 minutes while cooling to 75°C. Next, 95.1 parts by mass of bisphenol A type epoxy resin jER-828 (manufactured by Mitsubishi Chemical Corporation) was added, and the mixture was stirred at 75°C for 1 hour. The reaction temperature was returned to room temperature, the aqueous layer was extracted three times with ethyl acetate, and then the organic layer was dehydrated with sodium sulfate. Afterward, the sodium sulfate was removed by filtration, and the solvent was removed by distillation using an evaporator. 100 parts by mass of the obtained epoxy resin, 53.8 parts by mass of YS Polystar K125 (manufactured by Yasuhara Chemical Co., Ltd., softening point 125°C), and 1.3 parts by mass of triphenylphosphine were added and reacted at 160°C for 3 hours. After returning to room temperature, the mixture was diluted with methyl ethyl ketone to a solid content of 40% by mass to obtain epoxy resin solution 1.

[0059] (Epoxy resin solution 2) In a flask equipped with a stirrer, reflux condenser, and stirring device, 100 parts by mass of purified cardanol were weighed out while purging with nitrogen, and 3.1 parts by mass of p-toluenesulfonic acid monohydrate were added to prepare the reaction solution. The reaction solution was then heated to 100°C and stirred for 4 hours. 25 parts by mass of an aqueous sodium hydroxide solution (1.3 parts by mass of sodium hydroxide dissolved in 23.7 parts by mass of deionized water) was added to the reaction solution, and the mixture was stirred for 30 minutes while cooling to 75°C. Next, 67.1 parts by mass of bisphenol A type epoxy resin jER-828 (manufactured by Mitsubishi Chemical Corporation) was added, and the mixture was stirred at 75°C for 1 hour. The reaction temperature was returned to room temperature, the aqueous layer was extracted three times with ethyl acetate, and then the organic layer was dehydrated with sodium sulfate. Afterward, the sodium sulfate was removed by filtration, and the solvent was removed by distillation using an evaporator. 100 parts by mass of the obtained epoxy resin, 44 parts by mass of YS Polystar K125 (manufactured by Yasuhara Chemical Co., Ltd., softening point 125°C), and 1.4 parts by mass of triphenylphosphine were added and reacted at 160°C for 3 hours. After returning to room temperature, the mixture was diluted with methyl ethyl ketone to a solid content of 33% by mass. 7.3 parts by mass of diphenylmethane diisocyanate, 14.8 parts by mass of methyl ethyl ketone, and 0.03 parts by mass of triethylenediamine were added to the resin solution and reacted at room temperature for 2 hours to obtain epoxy resin solution 2.

[0060] <Manufacturing of aqueous compositions> As shown in the table, each material was placed in a flask, heated to 50°C while stirring at 8000 rpm using a homomixer, and after removing the methyl ethyl ketone under reduced pressure, the aqueous composition was prepared by filtering through a mesh filter. Note that the "Total" in the table refers to the total (parts by mass) after solvent removal. Furthermore, the "variable X" in the table was calculated using the following formula (I). X = Mass of solids of acid-containing acrylic resin with a glass transition temperature exceeding 100°C contained in the aqueous composition / (Mass of solids of acid-containing acrylic resin with a glass transition temperature exceeding 100°C contained in the aqueous composition + Mass of solids of surfactant contained in the aqueous composition) ... (I)

[0061] <Adhesion> In accordance with JIS K5600-5-6:1999 (cross-cut method), a cutter guide with a 2 mm gap spacing was used to make a grid pattern (25 squares; 5 vertically x 5 horizontally) on the test specimen. Cellophane adhesive tape was then applied to this grid pattern, and the tape was peeled off over 0.5 to 1.0 seconds by holding one end of the tape, and the area of ​​the peeled coating was measured. For the test specimens, an aqueous composition prepared to achieve a dry film thickness of 60 μm was applied to a steel plate (product name "SPCC-SB (0.8 mm x 70 mm x 150 mm)", manufactured by Paltec Co., Ltd.) using an applicator, and dried for one day under conditions of 23°C and 50% RH. The adhesion of the coating film was evaluated based on the area of ​​peeling relative to the total surface area of ​​the coating film, according to the following criteria. Those receiving a rating of 1 or 2 in the evaluation below were judged as "passing." Furthermore, those that failed to form a coating film with the aqueous composition were indicated as "no film formation" in the table. (Evaluation Criteria) 1: If the area of ​​paint peeling is less than 5% of the total area. 2: If the area of ​​paint peeling is 5% or more but less than 15% of the total area. 3. When the area of ​​paint peeling is 15% or more but less than 35% of the total area. 4. If the area of ​​paint peeling is 35% or more but less than 65% of the total area. 5. If the area where the paint film has peeled off is 65% or more of the total area.

[0062] [Table 1]

[0063] [Table 2]

[0064] The results from the examples confirmed that the aqueous compositions of the examples, which contain a neutralized acid group-containing acrylic resin with a glass transition temperature within a specific range, exhibit excellent adhesion to the coating film even when an epoxy resin containing a cardanol skeleton is included. [Industrial applicability]

[0065] The present invention provides an aqueous composition that exhibits excellent adhesion of the coating film, even when containing an epoxy resin containing a cardanol skeleton.

Claims

1. It contains an epoxy resin containing a cardanol skeleton, a neutralized acid group-containing acrylic resin, a surfactant, and water. The neutralized product of the acid group-containing acrylic resin is an aqueous composition satisfying the following (A) and / or (B). (A) The acid group-containing acrylic resin includes an acid group-containing acrylic resin having a glass transition temperature of 100°C or less. (B) The acid group-containing acrylic resin includes an acid group-containing acrylic resin having a glass transition temperature of over 100°C, and the variable X in the following formula (I) is 0.60 or less. X = Mass of solids of acid-containing acrylic resin with a glass transition temperature exceeding 100°C contained in the aqueous composition / (Mass of solids of acid-containing acrylic resin with a glass transition temperature exceeding 100°C contained in the aqueous composition + Mass of solids of surfactant contained in the aqueous composition) ... (I)

2. The aqueous composition according to claim 1, wherein the epoxy resin contains a polymerized cardanol skeleton.

3. The aqueous composition according to claim 1 or 2, wherein the epoxy resin contains a bisphenol skeleton.

4. The aqueous composition according to claim 1 or 2, wherein the acid group-containing acrylic resin has a weight-average molecular weight of 5,000 or more.

5. The aqueous composition according to claim 1 or 2, wherein the acid group-containing acrylic resin has an acid value of 50 mg KOH / g or more.

6. The aqueous composition according to claim 1 or 2, wherein the surfactant has an HLB value of 15 or more.

7. The aqueous composition according to claim 1 or 2, wherein the surfactant is at least one selected from the group consisting of polyalkylene oxide-based, polyoxyalkylene alkyl ether-based, and acetylene glycol-based surfactants.

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