Two-part aqueous coating composition

Abstract

To provide a two-part aqueous coating composition capable of forming a coating layer with superior adhesive strength and corrosion resistance.SOLUTION: A two-part aqueous coating composition contains (A) an epoxy resin, (B) a resin reactable with an epoxy resin, (C) a pigment, and (D) water. The coating composition is applied and dried for 7 days under conditions of 23°C and 50% humidity to form a coating layer, which exhibits an elastic modulus of 600-2400 N / mm2.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a two-liquid water-based coating composition, and in particular to a coating film having excellent adhesion and corrosion resistance. The present invention relates to a two-component water-based coating composition that can be formed. [Background technology]

[0002] In the field of coating for architectural and civil engineering structures, there have been concerns about the health of painters and residents. From the viewpoint of reducing damage and odor, solvent-based materials are being replaced by water-based materials. In response to this, a room temperature curing two-component water-based epoxy resin paint with excellent film strength, adhesion, and rust resistance has been developed. It is being done.

[0003] Japanese Patent Application Laid-Open No. 2021-1314 (Patent Document 1) describes a coating composition containing a coating component and a powder component. The coating material is an aqueous coating material including a resin component, and the coating forming component is an aqueous epoxy resin emulsion. The formed coating has a gel fraction of 10% or more, and the powder component is a rust-preventive pigment, and calcium carbonate, and the powder component is mixed in an amount of 50 to 30 parts by weight of the resin component. 00 parts by weight, and the powder component contains 30 to 90% by weight of the calcium carbonate. The invention of the water-based coating material is described, and the water-based coating material has the following characteristics: coating film strength, adhesion, rust prevention In addition, JP 2021-1315 A (Patent Document 2) states that The water-based coating material described in Patent Document 1 contains a color pigment containing titanium oxide and a red iron oxide pigment. A combined invention is described.

[0004] Japanese Patent Application Laid-Open No. 2009-149791 (Patent Document 3) describes: (I) an epoxy resin emulsion The combination of the base material containing amine and pigment and (II) an amine hardener is used immediately after use. It is a two-component water-based anticorrosive paint that is mixed before application, and the pigment content in the main component (I) is The composition contains a phosphoric acid-based rust-preventive pigment as a part of the composition, and an amine curing agent (II) is one of the components. The active hydrogen equivalent of the cyclic structure is in the range of 80 or more and less than 1000. The present invention describes an invention for a two-component water-based anticorrosive paint that contains triamine (IIa), Liquid-type water-based anticorrosive paints have good hardening properties even under room temperature drying conditions, and are also effective against iron, zinc, and other metals. It is possible to form an anticorrosive coating film with excellent corrosion resistance on substrates such as steel and non-ferrous materials. This allows the beauty of the coated object to be maintained for a long time even in harsh environments. It states that:

[0005] JP 2019-515991 A (Patent Document 4) is a two-component epoxy resin paint. (a) an epoxy resin component; and (b) an amine component for curing the epoxy resin component. The amine component comprises: (i) at least one polyamide curing agent; and (ii) at least one amine component selected from the group consisting of: and at least one Mannich base hardener, At least one of the curing agents comprises at least one alicyclic polyfunctional amine. Derived from a polyfunctional amine, the alicyclic polyfunctional amine accounts for 3% of the total amount of the polyfunctional amine. 0% by weight or more, and the weight ratio of the epoxy resin component (a) to the amine component (b) is The invention of a two-component epoxy resin coating with a ratio of 100:8 to 100:20 is described, which This two-component epoxy resin coating offers a good balance between long pot life and fast drying speed. It states that

[0006] Japanese Patent Application Laid-Open No. 2018-53028 (Patent Document 5) describes a method for producing a cellulose ester resin by mixing an epoxy resin and an amine resin. A two-component reactive curing type water-based coating composition for undercoat coating, comprising: Epoxy resin with epoxy equivalent of 400-1000g / eq and epoxy equivalent of 150-300g The invention relates to a coating composition having a weight ratio of 90:10 to 60:40 / eq epoxy resin. This provides a two-component reactive curing type primer for undercoat paint that provides an undercoat film with excellent chemical resistance. It is described that a water-based coating composition can be provided. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent Publication No. 2021-1314 [Patent Document 2] Patent Publication No. 2021-1315 [Patent Document 3] JP 2009-149791 A [Patent Document 4] JP 2019-515991 A [Patent Document 5] JP 2018-53028 A Summary of the Invention [Problem to be solved by the invention]

[0008] As mentioned above, epoxy resin-based water-based coating compositions have been proposed. Generally, alkoxy resin is known as a resin with excellent adhesive properties, and when used in water-based paints, In this case, the adhesive properties of the epoxy resin are not fully developed compared to when it is used in organic solvent-based paints. It was felt that they were not able to demonstrate their capabilities.

[0009] Therefore, the object of the present invention is to provide a two-component water-based paint capable of forming a coating film having excellent adhesion and corrosion resistance. The present invention provides a composition. [Means for solving the problem]

[0010] In order to achieve the above object, the present inventors have conducted research and discovered an epoxy resin-based two-component water-based The elastic modulus of the coating film formed from the coating composition is 600 to 2400 N / mm 2 When adjusted to It has been found that a coating film having excellent adhesion can be formed even with water-based paints, and the present invention has been completed. This led to...

[0011] Therefore, the coating composition of the present invention is a composition comprising (A) an epoxy resin and (B) a resin that reacts with an epoxy resin. A two-component water-based coating composition comprising a resin, (C) a pigment, and (D) water, the coating composition comprising After drying for 7 days at 23°C and 50% humidity, the elasticity of the coating is 600-240 0N / mm 2 It is a coating composition.

[0012] In a preferred embodiment of the coating composition of the present invention, the coating composition is applied and then stored at 23°C and 50% humidity. When dried under the above conditions for 7 days, the gel fraction of the coating film is 80% or more.

[0013] In another preferred embodiment of the coating composition of the present invention, the coating composition is applied and then dried at 23° C. and humidity of 5 The amount of solvent remaining in the coating film after drying for 7 days under 0% conditions is less than 8.0%.

[0014] In another preferred embodiment of the coating composition of the present invention, the resin (B) reactive with the epoxy resin is At least, the modified polyamine contains a cyclic structure.

[0015] In another preferred embodiment of the coating composition of the present invention, the resin (B) reactive with the epoxy resin is (B) a modified polyamine having at least a cyclic structure, which reacts with the epoxy resin The content of the modified polyamine having a cyclic structure in the resin is 50 to 100% by mass. It is a combination. Effect of the Invention

[0016] According to the present invention, a two-liquid water-based coating composition capable of forming a coating film having excellent adhesion and corrosion resistance is provided. can be provided. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The present invention will be described in detail below. The present invention relates to an epoxy resin, a compound that reacts with an epoxy resin, and a polyimide compound that reacts with an epoxy resin. The present invention relates to a two-component water-based coating composition comprising a resin, a pigment, and water. The product is also referred to as "the two-liquid water-based coating composition of the present invention" or "the coating composition of the present invention." The "epoxy resin" is the component (A), and is also referred to as "(A) epoxy resin." The resin that reacts with oil is the component (B), and is also called the resin that reacts with epoxy resin (B). "Pigment" is the (C) component, and is also referred to as "(C) pigment." "Water" is the (D) component, Also referred to as "(D) water."

[0018] In this specification, a water-based coating composition is a coating composition that contains water as the main solvent. The water used in the coating composition of the present invention is not particularly limited, but may be tap water or ion-exchange water. Suitable examples of water include fresh water, distilled water, and other pure water. To prevent the growth of mold and bacteria, the water used is sterilized by ultraviolet light, etc. In the coating composition of the present invention, the amount of water is preferably 20 to 60% by mass. It is preferable that the content is 30 to 50 mass %.

[0019] In addition, the amount of non-volatile matter in the coating composition of the present invention is 40 to 80 mass %. In this specification, the non-volatile content is preferably 50 to 70 mass %. This refers to the components excluding volatile components such as solvents, and is the final component that will form the coating film. In the present invention, the coating composition was dried in an oven at 110°C for 3 hours. The components remaining in the container are treated as non-volatile matter.

[0020] In this specification, a two-liquid type coating composition is a coating composition consisting of a base agent and a curing agent. Two-liquid coating compositions are made by mixing the base agent, the curing agent, and additives selected as necessary at the time of application. In the present invention, the epoxy resin-containing agent (A) is the main agent. (B) The agent containing the resin that reacts with the epoxy resin is the hardener. (C) The pigment is the main component. (D) Water may be mixed with either the base or hardener, but is usually included in the base. It is usually included in the base agent and hardener, but it may be used only in the base agent. Some of them may be used as additives when mixing the base resin and hardener.

[0021] Epoxy resin is a resin that has epoxy groups in its molecules, and hardens when the epoxy groups react. Epoxy resins are generally used for substrates, especially metal substrates. It has high adhesion to substrates, and is also resistant to environmental factors (e.g. water, acid, etc.) that affect the corrosion of substrates, especially metal substrates. It is also known as a resin with excellent corrosion resistance because it has the effect of shielding the base material from corrosion (e.g., chemicals). On the other hand, when used in water-based paint compositions, the adhesiveness and However, the present invention has not been able to fully demonstrate the effect of improving corrosion resistance. According to the study, by adjusting the elastic modulus and gel fraction of the coating film formed, it is possible to obtain a water-based coating composition having a high elasticity and a high gel content. Even if there is a coating, adhesion and corrosion resistance can be sufficiently improved.

[0022] The epoxy resin is preferably a resin having at least two epoxy groups in one molecule. Preferably, for example, a polyhydric alcohol or a polyhydric phenol is reacted with a halohydrin. Specific examples include bisphenol A epoxy resin, halogenated bisphenol A, etc. Enol A type epoxy resin, Novolac type epoxy resin, Polyglycol type epoxy resin , Bisphenol F type epoxy resin, Epoxidized oil, 1,6-hexanediol diglyceride diglycidyl ether and neopentyl glycol diglycidyl ether. Epoxy resins are made to have rigid structures such as aromatic rings in order to increase the elastic modulus of the resulting coating film. It is preferred that the compound has the following formula:

[0023] Epoxy resins include epoxy resin emulsions, epoxy resin dispersions and epoxy resins. It is preferable that the resin is blended in the form of either an aqueous solution of an oxy resin or an aqueous solution of an oxy resin. The emulsion means an emulsion in which a resin is dispersed in an aqueous medium whose main component is water. A resin dispersion is a liquid in which a resin is dispersed in an aqueous medium whose main component is water. The term "aqueous resin solution" refers to a solution in which a resin is dissolved in an aqueous medium mainly composed of water. The epoxy resin emulsion is not particularly limited, but may be prepared by a conventional forced emulsification method (emulsifier By using a method that uses a high-speed mixer, etc., epoxy resin is mixed in an aqueous medium whose main component is water. The emulsion is prepared by emulsifying fat. Here, examples of the emulsifier include polyoxyethylene. Polyethylene alkylphenol ether nonionic surfactant, polyoxyethylene polyoxyethylene polyethers such as propylene block copolymers; nonionic surfactants and poly Examples of the compound include an adduct of at least one of ethers and a diisocyanate compound. The emulsifier may be used alone or in combination of two or more. Commercially available epoxiresin emulsions include, for example, Epolsion EA-1, 2, 3, 7, 12, 20, 55, and HD2 (Henkel Japan); Yukaresin KE-002, K E-116, E-1022, KE-301C (Yoshimura Oil Chemicals); Adeka Resin EM-1 01-50 (Adeka); jER W1155R55, jER W3435R67, j ER W2821R70 (manufactured by Mitsubishi Chemical Corporation), etc. Examples of commercially available products of ethylene glycol include Beckpox EP2381 (manufactured by Allnex); I-REZ6530-WH-53 (manufactured by Momentive) and others.

[0024] The epoxy resin may be a modified epoxy resin. For example, urethane modified epoxy resin, amine modified epoxy resin, isocyanate modified epoxy Resin, acrylic modified epoxy resin, polyester modified epoxy resin, dimer acid modified epoxy Examples of the resin include alkoxy resin.

[0025] The epoxy equivalent of the epoxy resin is preferably 100 to 1,000 g / eq. 200-700g / eq is more preferable, and 300-600g / eq is more preferable. More preferably, the epoxy equivalent is 100 g / eq or more. On the other hand, if the epoxy equivalent is less than 1,000g / eq, the leveling ability decreases. When using multiple epoxy resins, each epoxy resin should be It is preferred that the average epoxy equivalent weight of the epoxy resin mixture is within the range specified above. The epoxy equivalent of the resin is based on JIS K 7236:2001 "Epoxy equivalent of epoxy resin This can be found by following the procedure for finding the answer.

[0026] In the coating composition of the present invention, the amount of epoxy resin in the non-volatile matter is 30 to 70 mass %. The epoxy resin may be used alone or in combination of two or more kinds. It may also be used.

[0027] Resins that react with epoxy resins react with epoxy resins, especially with their epoxy groups, to cause a curing reaction. It is a resin used to promote or control the reaction. The resin is preferably a resin having an active hydrogen that reacts with an epoxy group, and more preferably a polyamine resin. Polyamine resin is a resin that has at least two amino groups in one molecule. For example, triamine resins are produced by polycondensation of amines and aldehydes into alcohols. By etherifying amines with ethyleneimine, amines with heterocyclic structures (e.g., ethyleneimine) can be obtained. by ring-opening polymerization of amines and carboxylic acids, or by condensation of amines and formaldehyde. Resins made by the Mannich reaction of aldehydes and ketones or phenols. Here, resins made by condensation of amines and carboxylic acids contain amines in the molecule. Polyamine resins that also contain amido bonds are called "polyamidoamine resins" or "polyamidoamines." Also, ethylene oxide is used for the etherification of amines with alcohols. Ring-opening polymerization of alkylene oxides such as propylene oxide can be utilized.

[0028] Examples of amines that can be used in the production of polyamine resins include ethylenediamine, thiamine, and ethylenediamine. Trimethylenediamine, tetramethylenediamine, pentamethylenediamine, triamine propane, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, Aliphatic polyamines such as isophoronediamine and 1,3-bisaminomethylcyclohexane; Phenylenediamine, metaxylylenediamine, paraxylylenediamine, diaminodiphenyl Aromatic polyamines such as phenylmethane; amines with heterocyclic structures such as ethyleneimine, etc. Examples include:

[0029] The polyamine resin may be a modified polyamine resin. The polyamine resin is a polyamine resin in which some of the amino groups have been modified. The amino groups can be modified by known methods. For example, amidation of amino groups, Mannich reaction of amino groups with carbonyl compounds, etc. reaction, and addition reaction of amino group with epoxy group.

[0030] The resin that reacts with the epoxy resin contains at least a modified polyamine having a cyclic structure. It is preferable to use a modified polyamine having a cyclic structure as the resin that reacts with the epoxy resin. By using it, the elastic modulus of the resulting coating film can be increased. The polyamine resin is a polyamine resin in which some of the amino groups are modified. The modification can be, for example, the aryl group of the amino group. Amidation, Mannich reaction of amino groups with carbonyl compounds, addition reaction of amino groups with epoxy groups As the modified polyamine, Mannich modified polyamidoamine is preferable. stomach.

[0031] The content of the modified polyamine having a cyclic structure in the resin that reacts with the epoxy resin is The ratio is preferably 50 to 100% by mass, and more preferably 60 to 90% by mass. More preferred.

[0032] The resin that reacts with the epoxy resin contains at least a modified polyamine having a cyclic structure. It is more preferable to use a modified polyamine having a cyclic structure. The modified polyamine having a cyclic structure is produced by condensing the cyclic structure during its production. It is possible to obtain the polyamine resin by using a substance having the structure: Examples of amines having a cyclic structure that can be used include N-aminoethylpiperazine. Piperazines such as 1,3-bisaminoethylcyclohexane, isophoronediamine, 1 -Cyclohexylamino-3-aminopropane, 1,4-diaminocyclohexane, di( (aminocyclohexyl)methane, 1,3-di-(aminocyclohexyl)propane, 2, 4-diamino-cyclohexane N,N'-diethyl-1,4-diaminocyclohexane, Aliphatic polyamines such as 3,3'-dimethyl-4,4'-diaminocyclohexylmethane; Phenylenediamine, metaxylylenediamine, paraxylylenediamine, diaminodiphenyl Examples of the polyamines include aromatic polyamines such as phenylmethane and the like. Amines are sometimes called alicyclic polyamines. They can also be used to produce polyamine resins. Examples of the alcohols having a cyclic structure include phenol and its derivatives. Examples of phenol derivatives include phenols in which the benzene ring is substituted with a hydrocarbon group. and in particular linear or branched hydrocarbons which may have one or more unsaturated bonds. The hydrocarbon group may be a phenol substituted with a hydrocarbon group having 10 to 2 carbon atoms. 0 long chain hydrocarbon group, particularly an alkyl group. Examples of the epoxy resin include cardanol. The resin that reacts with the epoxy resin has a cyclic structure. From the viewpoint of increasing the elastic modulus of the resulting coating film, it is preferable to use a compound having a rigid structure such as an aromatic ring. More preferably, the structure is

[0033] From the viewpoint of increasing the elastic modulus of the coating film, modified polyamines having a cyclic structure are used in combination with amines and holoamines. A polyamine resin obtained by the Mannich reaction of aldehyde and a phenol derivative. Here, the cyclic structure is preferably derived from a phenol derivative, and The amine is preferably a chain compound (or a non-cyclic compound) such as ethylenediamine. The phenol derivative is as described above, and cardanol is particularly preferred. Such modified polyamine resins are also called phenalkamine-based hardeners.

[0034] As described above, by using a modified polyamine, particularly a modified polyamine having a cyclic structure, The effect of increasing the elastic modulus of the coating film is obtained. On the other hand, modified polyamines, especially those having a cyclic structure, The modified polyamines tend to have low reactivity with epoxy resins. The resin that reacts with the modified polyamine is a modified polyamine having a cyclic structure, and the modified It is preferable to use a resin that does not fall under the category of polyamine in combination with the epoxy resin. The reactivity of the resin that reacts with the modified polyamine can be ensured. The resin is not particularly limited, and examples thereof include polyoxyethylenediamine, ... Polyoxyethylene amines such as dipropylene diamine (also called polyether amines) ) etc. can be used.

[0035] Resins that react with epoxy resins are modified polyamines and resins that do not fall under modified polyamines. In the case where the epoxy resin is reacted with the modified polyamine, the ratio of the modified polyamine to the total resin reacting with the epoxy resin is 50 to 100%. 99% by mass, and the proportion of resins that do not fall under the category of modified polyamines is 1-50% by mass. is preferred.

[0036] Resins that react with epoxy resins are available in the form of emulsions, dispersions, and aqueous solutions. It is preferable to incorporate it in this form.

[0037] The active hydrogen equivalent of the resin that reacts with the epoxy resin is preferably 80 to 350 g / eq. The viscosity of the resin reacting with the epoxy resin is preferably 100 to 250 g / eq, and more preferably 100 to 250 g / eq. The active hydrogen equivalent of a resin is the number of grams of resin that contains 1 equivalent of active hydrogen [g / eq]. It is the value obtained by dividing the molecular weight of the resin reacting with the amino group by the number of hydrogen atoms of the amino group per molecule. .

[0038] In the coating composition of the present invention, the amount of resin reacting with the epoxy resin in the non-volatile matter is 5 to 100%. The content of the epoxy resin in the epoxy resin-reactive resin composition is preferably 20% by mass. Two or more of them may be used in combination.

[0039] The pigment is not particularly limited, and may be any pigment commonly used in the paint industry, such as an anti-rust pigment, an extender pigment, or a color pigment. The pigments used in the present invention can be used. The pigments may be used alone or in combination of two or more. They may also be used in combination.

[0040] Examples of anti-rust pigments include zinc powder, zinc oxide, barium metaborate, and calcium silicate. Aluminum phosphate, condensed aluminum phosphate, aluminum tripolyphosphate, phosphorus Zinc acid, zinc phosphite, potassium phosphite, calcium phosphite, aluminum phosphite , zinc calcium phosphate, zinc aluminum phosphate, zinc phosphomolybdate, phosphomolybdate Examples include aluminum vanadate, magnesium phosphate, and mixed vanadate / phosphate pigments. Among these, phosphoric acid-based rust-preventive pigments are preferred from the viewpoint of corrosion prevention. Examples of pigments include salts of phosphoric acid compounds such as phosphoric acid, phosphorous acid, and polyphosphoric acid (magnesium salts, etc.). Examples of the salts include sodium salts, calcium salts, zinc salts, aluminum salts, and phosphomolybdates. In the coating composition of the present invention, the amount of the rust-preventive pigment in the non-volatile matter is, for example, 1 to 20% by mass. It is.

[0041] Examples of extender pigments include silica, talc, mica, calcium carbonate, and barium sulfate. Among these, calcium carbonate is preferred from the viewpoint of chemical resistance. In the coating composition of the present invention, the amount of the extender pigment in the non-volatile matter is, for example, 10 to 50% by mass. do.

[0042] Examples of color pigments include titanium oxide, iron oxide, carbon black, yellow lead, and molybdenum. Orange, Ultramarine, Prussian Blue, Phthalocyanine Blue, Phthalocyanine Green, Cinchona Don Red, Naphthol Red, Benzimidazolone Yellow, Hansa Yellow, Benz imidazolone orange, dioxazine violet, etc. In the composition, the amount of the color pigment in the nonvolatile content is, for example, 1 to 20% by mass.

[0043] At least a part of the pigment may be a scaly pigment. Based on the scale shape, the coating film has the effect of inhibiting the intrusion of corrosive factors such as water, oxygen, and chlorides, and By reducing the internal stress of the coating film, the adhesion of the coating film is improved. The scaly pigment can be further improved and a thick coating film can be advantageously formed. , talc, mica, kaolin clay, glass flakes, micaceous iron oxide, aluminum and Other examples include metal pigments. The scale-like pigments are the above-mentioned anti-rust pigments, extender pigments, and coloring pigments. In the coating composition of the present invention, the amount of the scaly pigment in the nonvolatile matter is , for example, 0 to 50% by mass.

[0044] In the present invention, in order to increase the elastic modulus of the resulting coating film, the aspect ratio is preferably greater than 1. It is preferable to use a scale-like pigment having an elastic modulus of less than 120. From the viewpoint of increasing the size of the particles, it is preferable to use an average aspect ratio of 30 or more. is preferably from 1 to 30.

[0045] In this specification, the average aspect ratio of the scaly pigment is the average particle diameter (D) of the scaly pigment. The average particle size is the ratio (D / T) of the average thickness (T) to the volumetric particle size distribution. 50% particle size (D 50 ) and is measured using a laser diffraction / scattering particle size distribution analyzer. The particle size of the scaly pigment is calculated from the particle size distribution obtained by the laser diffraction / scattering method. The average thickness is expressed as the diameter of 100 or more particles using a SEM (scanning electron microscope). The thickness of the scaly pigment is measured, and the average value of these thicknesses is referred to.

[0046] The average particle size of the scale-like pigment is preferably 3 to 40 μm, and more preferably 3 to 20 μm. It is more preferable that

[0047] The coating composition of the present invention preferably has a pigment volume concentration (PVC) of 10 to 40%. In the present invention, in order to increase the elastic modulus of the resulting coating film, From the viewpoint of reducing the amount of PVC, it is preferable that the PVC is high. It is preferable that the above.

[0048] In this specification, the pigment volume concentration (PVC) entration is the ratio of the total volume of pigments to the total volume of non-volatile matter in a paint composition. This is the percentage of non-volatile matter, calculated from the composition and specific gravity of the components that make up the non-volatile matter. can be done.

[0049] The coating composition of the present invention is applied and dried for 7 days under conditions of 23°C and 50% humidity. The elastic modulus of the coating film when it is heated is 600 to 2400 N / mm 2 900~2400N / m m 2 It is preferable that the strength is 1300 to 2400 N / mm 2 It is more preferable that: The inventors set the elastic modulus of the coating to 600 N / mm 2 By doing so, the adhesion of the coating film can be improved. The elastic modulus is a physical property that indicates resistance to deformation. The higher the modulus, the higher the resistance to deformation, which improves the adhesion of the coating. It is believed that the elastic modulus of the coating is 2400N / mm 2 If it is less than this, adhesion is It exhibits excellent corrosion prevention without causing poor coating film formation.

[0050] (How to determine the elastic modulus of a coating film) Using an applicator, apply a dry film thickness of 50 to 70 μm onto a substrate (e.g., a polypropylene plate). The coating composition is applied so that the thickness becomes 1.0 mm, and then dried for 7 days under conditions of 23°C and 50% humidity. Cut out a strip of 50mm x 10mm from the coating to prepare a sample for measurement. The tensile test was carried out at 23°C and 50% humidity at a speed of 5mm / min. It is calculated from the slope (proportionality constant) within the range in which the change is proportional.

[0051] Conventional epoxy resin-based water-based paint compositions have a coating film elasticity of 600N / mm 2 However, the inventors of the present invention have used modified polypropylene as a resin that reacts with epoxy resin. By using amines, particularly modified polyamines having a cyclic structure, the elastic modulus of the resulting coating film can be improved. Higher, 600N / mm 2 It was found that a coating film having an elastic modulus of 100% or more can be formed. In addition, when drying the coating at high temperatures (for example, temperatures above 50°C) or when the pigment volume concentration (PVC ) exceeds 40%, the elastic modulus of the coating film formed is 2400N / mm 2 Exceeding It is expected that the elastic modulus will be 2400N / mm 2 Coatings exceeding this value tend to become hard and brittle. The toughness is lost, and poor film formation and cracks may occur.

[0052] The coating composition of the present invention is applied and dried for 7 days under conditions of 23°C and 50% humidity. The gel fraction of the coating film when it is heated is preferably 80% or more, and more preferably 90% or more. The gel fraction is an index of the reactivity of an epoxy resin and a resin that reacts with the epoxy resin. In the present invention, if the gel fraction of the coating film is less than 80%, the reactivity between these resins becomes The water resistance is not sufficient, and re-dissolution occurs when a paint is applied over the coating. In some cases, defects such as failure to exhibit corrosion resistance or anticorrosion properties may occur.

[0053] For example, modified polyamines, particularly those having a cyclic structure, are used as resins that react with epoxy resins. When modified polyamines are used, the effect of increasing the elastic modulus can be obtained, but the epoxy resin The reactivity with the solvent tends to decrease, and the gel fraction of the coating film may fall below 80%. In such a case, the resin that reacts with the epoxy resin corresponds to a modified polyamine having a cyclic structure. It is preferable to use a resin that does not have a high elasticity. N / mm 2 It is possible to achieve a gel fraction of 90% or more while still being within the range of .

[0054] (How to determine the gel fraction of a coating film) Using an applicator, apply a dry film thickness of 50 to 70 μm onto a substrate (e.g., a polypropylene plate). The coating composition was applied so that the thickness of the coating was m, and the coating was dried for 7 days under conditions of 23°C and 50% humidity. The coating film is peeled off from the plate, the mass of the coating film obtained is measured, and this mass is designated as W0. Soak in tetrahydrofuran (THF) at 23°C for one day. After soaking, take it out of the THF. The coating film is then completely dried and its mass is measured. The mass of the coating film at this point is designated as Wd. . Then, the mass loss amount ΔW (= W0-Wd) is divided by W0 to convert it into a percentage. The gel fraction is calculated from the difference between 100% and the mass reduction rate. Calculation formula: Gel fraction = 100-(W0-Wd) / W0 x 100

[0055] The coating composition of the present invention is applied and dried for 7 days under conditions of 23°C and 50% humidity. The amount of solvent remaining in the coating film when the coating is heated is preferably less than 8.0%, and more preferably 7.0% or less. It is preferable that the content of the solvent is 6.5% or less, and more preferable that the content of the solvent is 6.5% or less. The plasticizing effect may cause problems such as a decrease in elasticity and insufficient adhesion. By reducing the proportion of volatile matter such as water and film-forming agents used in the coating composition, The residual amount of the solvent can be kept low.

[0056] (How to determine the amount of solvent remaining in a coating film) Using an applicator, apply a dry film thickness of 50 to 70 μm onto a substrate (e.g., a polypropylene plate). The paint composition is applied so that the mass of the paint composition used for painting is W0 After painting, the coating is dried for 7 days at 23°C and 50% humidity, and the weight of the resulting coating is This is the actual coating mass W. From the mass of the dispersion, the theoretical value of the final dry coating mass is calculated, and this is taken as the theoretical coating mass Wz. The difference between the measured and theoretical coating weights (W-Wz) is divided by the coating weight W0 and converted into a percentage. The remaining amount of solvent is calculated by the above calculation. Calculation formula: remaining amount of solvent = (W-Wz) / W0 x 100

[0057] The coating composition of the present invention contains, as other components, components other than component (A) or component (B). Resins that do not fall under component (B), crosslinking agents, film-forming aids, antifreeze agents, surface conditioners (or wetting agents), etc. agents), dispersants, defoamers, viscosity adjusters, thickeners, rust inhibitors that do not fall under the category of anti-rust pigments, Lash rust prevention agent, anti-settling agent, anti-skinning agent, anti-dripping agent, anti-color separation agent, gloss Desiccant, adhesion promoter, leveling agent, drying agent, catalyst, plasticizer, anti-mold agent, antibacterial agent, anti-virus Depending on the purpose, additives such as antiseptics, preservatives, insecticides, antistatic agents and conductive agents may be added appropriately. This can be done.

[0058] The coating composition of the present invention is prepared by preparing the base agent and the curing agent in advance, and then mixing the base agent, the curing agent and any necessary components. Depending on the type of paint, additives can be mixed at the time of painting. can be prepared by mixing various components appropriately selected as needed. .

[0059] The coating composition of the present invention has a viscosity of 1 to 1000 (P a s, 23°C) and the viscosity at a shear rate of 1000 (1 / s) is 0.05 to 10 (Pa·s, 23°C).

[0060] In this specification, the viscosity is measured using a rheometer (e.g., a rheometer manufactured by TA Instruments). The measurement is performed using a thermometer (ARES) after adjusting the liquid temperature to 23°C.

[0061] The coating method for the coating composition of the present invention is not particularly limited, and may be any known coating method, such as brush coating. Coating, roller painting, trowel painting, spatula painting, flow coater painting, spray painting (e.g. Earth spray painting, airless spray painting, etc. can be used.

[0062] The drying method of the coating composition of the present invention is not particularly limited, and may be natural drying at ambient temperature or drying with a dryer, etc. or forced drying using a dryer.

[0063] The coating composition of the present invention is capable of forming a coating film having excellent adhesion, and preferably It is also possible to improve the corrosion resistance. For this reason, the coating composition of the present invention can be used as an undercoat coating. This is preferable.

[0064] The substrate to be coated with the coating composition of the present invention is, for example, epoxy resin, ABS resin, polycarbonate. polycarbonate, polyvinyl chloride, polystyrene, acrylic resins, such as polymethylmethacrylate Acrylates (PMMA), Polyethylene Terephthalate (PET), Polyolefins, e.g. For example, plastic substrates such as polypropylene (PP), steel, zinc-plated steel, tin-plated steel, Stainless steel, magnesium alloy, aluminum, aluminum alloy, titanium, titanium alloy Metal substrates such as gold, cement, mortar, concrete, slate, gypsum, calcium silicate Non-metallic inorganic substrates such as rubber, glass, ceramics, calcium carbonate, marble, and artificial marble Materials based on wood, wood-based materials, paper-based materials, composite materials that combine two or more of these materials Examples of the composite substrate include wood fiber reinforced cement boards, fiber reinforced Composite substrates such as strong cement boards, fiber reinforced cement / calcium silicate boards, various surface treatments, e.g. For example, metal substrates that have been oxidized, plastics whose surfaces are coated with inorganic substances, etc. Substrates (eg, glass-coated plastic substrates) and the like.

[0065] The coating composition of the present invention is capable of forming a coating film having excellent adhesion and preferably excellent corrosion resistance. Therefore, the coating target is a metal substrate or a composite substrate made of metal and other materials. It is preferred.

[0066] The substrates are available in various shapes, for example, two-dimensional shapes such as films, sheets, and plates. The surface of the substrate is smooth and has a three-dimensional shape. Alternatively, it may have projections and recesses.

[0067] The surface of the base material is pretreated with degreasing, chemical conversion coating, polishing, etc., and is also treated with sealers and primers. The surface may be coated with paint such as zinc-rich paint, plated, or metal sprayed.

[0068] The substrate may have a previous coating film on its surface. The previous coating film may be a part of the substrate surface or In this specification, the old coating film refers to a coating film that has not yet been painted, particularly a coating film that has not yet been repaired. This refers to a coating that is already present on the substrate at the time of application.

[0069] When the substrate has a previous coating film on its surface, the substrate surface including the previous coating film is coated with the coating composition of the present invention. If the old coating is in good condition, it can be peeled or removed from the surface of the substrate. The coating composition of the present invention can be applied onto the old coating film without the need for any additional coating. Since contaminants such as dust and dirt are attached, removing the contaminants will allow new paint to be applied to the old coating. The adhesion of the new coating can be improved. As a method for removing contaminants, high-pressure water washing is used. Alkaline cleaning with caustic soda, acid cleaning with inorganic or organic acids, bleaching with perchloric acid, etc. Examples of cleaning methods include cleaning with a whitening agent, scraping and wiping with a cloth.

[0070] The old coating preferably contains a resin, for example, an acrylic resin or a silicone resin. , acrylic silicone resin, styrene acrylic copolymer resin, polyester resin, fluororesin Fat, rosin resin, petroleum resin, coumarone resin, phenolic resin, urethane resin, melamine resin Grease, urea resin, epoxy resin, cellulose resin, xylene resin, alkyd resin, aliphatic carbon Hydrogen resin, butyral resin, maleic acid resin, fumaric acid resin, vinyl resin, amine resin , ketimine resins, and resins obtained by modifying these resins (modified resins). may be used alone or in combination of two or more.

[0071] Other ingredients in the old coating include pigments, dispersants, surface conditioners, antioxidants, plasticizers, Rust inhibitors, solvents, antibacterial agents, antiviral agents, viscosity regulators, fillers, defoamers, charge control agents, stress Relaxants, penetrants, light-guiding materials, glittering materials, magnetic materials, fluorescent materials, UV absorbers, radical scavengers, etc. Various additives may be included.

[0072] The coating composition of the present invention has a coating film elasticity modulus of 7 days after drying at 23°C and 50% humidity. 600~2400N / mm 2 Therefore, the resistance to external stress is increased, resulting in As a result, it is possible to form a coating film that has excellent adhesion to the substrate and the old coating film, and preferably also has excellent corrosion resistance. In addition, it is possible to select the appropriate undercoat or topcoat paint according to the exterior environment. In addition to providing adhesion and corrosion resistance to the substrate and old coating, it also provides stain resistance and water repellency. To create a coating film with properties that are adapted to the environment, such as durability, weather resistance, and environmental barrier properties. This becomes possible.

[0073] When the coating composition of the present invention is used as an undercoat coating, a topcoat coating is applied on the undercoat coating. Alternatively, a middle coat film and a top coat film can be formed in that order.

[0074] The paint for forming the intermediate coating film or the top coating film is water-soluble, like the paint composition of the present invention. These coating compositions preferably contain a resin, a crosslinker, a pigment, water, , film-forming aid, antifreeze agent, surface conditioner (also called wetting agent), dispersant, defoamer, viscosity adjuster Stabilizer, thickener, rust inhibitor, anti-settling agent, anti-skinning agent, anti-dripping agent, anti-color separation agent, gloss Desiccant, adhesion promoter, leveling agent, drying agent, catalyst, plasticizer, anti-mold agent, antibacterial agent, anti-virus Antiseptics, preservatives, insecticides, UV absorbers, radical scavengers, antistatic agents and conductive agents etc. can be appropriately blended depending on the purpose. EXAMPLES

[0075] The present invention will be described in more detail below with reference to examples. Not limited to this.

[0076] <Preparation example of coating composition> The raw materials were mixed according to the formulations shown in Tables 1 and 2 to prepare the base resin and the hardener. The base resin and the hardener were mixed with water for dilution in the mixing ratio shown in Table 3 to prepare a coating composition. The coating composition was evaluated. The formulations and mixing ratios shown in Tables 1 to 3 are based on mass.

[0077] Details of the materials used in preparing the coating compositions are provided below. Epoxy resin 1: ADEKA Resin EM101-50 (Epoxy resin emulsion manufactured by ADEKA) John: Non-volatile content 47% by mass, epoxy equivalent 1075 g / eq) Epoxy resin 2: jER W2821R70 (Epoxy resin emulsion manufactured by Mitsubishi Chemical Corporation: Non-volatile content 70% by mass, epoxy equivalent 220-240g / eq) Anti-rust pigment: Aluminum tripolyphosphate K-WHITE#84S (manufactured by Teika Co., Ltd.) Extender pigment 1: Calcium carbonate (average particle size 6 μm) Extender pigment 2: Talc (average particle size 13 μm, aspect ratio less than 20) Color pigment 1: Titanium dioxide (white pigment) Color pigment 2: Carbon black (black pigment) Color pigment 3: Iron oxide (Oukatsu color pigment) Color pigment 4: Iron oxide (rust pigment) Dispersant: FLORENE GW-1640 (Kyoeisha Chemical Co., Ltd.) Film forming agent: Dipropylene glycol n-butyl ether Defoamer: SN DEFOAMER 1312 (San Nopco) Thickener: SN Thickener 665T (San Nopco, urethane modified polyether compound, Non-volatile content 30%) Polyamine resin 1: Cardolite NX-8401 (Cardolite Co., Ltd.) Resin emulsion; non-volatile content 57% by mass, active hydrogen equivalent 290g / eq) Polyamine resin 2: Daitoclar X-7024 (amine resin emulsion manufactured by Daito Sangyo Co., Ltd.) (Non-volatile content 50%, active hydrogen equivalent 392 g / eq) Polyamine resin 3: Jeffamine T-403 (polyamine resin manufactured by HUNTSUMAN) Teramine; non-volatile content 100% by mass, active hydrogen equivalent 81 g / eq) Polyamine resin 4: BECKOPOX EH623W (water-soluble amine resin manufactured by ALLNEX) Fat: non-volatile content 80% by mass, active hydrogen equivalent 200 g / eq) Rust inhibitor 1: HALOX650 (manufactured by ICL Phosphate Specialty) Machine rust inhibitor, non-volatile content 100% by mass Rust inhibitor 2: Sodium nitrite

[0078] <Coating film preparation method 1> The paint prepared in the above <Preparation Example of Paint Composition> was applied to a polypropylene board (2.0 x 70 x 1 50 mm) using an applicator so that the dry film thickness is 50 to 70 μm. The plate was dried for 7 days in an environment of 23°C and 50% relative humidity to obtain a coated plate.

[0079] <Coating film preparation method 2> Sandblasted board (3.2 x 70 x 150 mm) with modified epoxy resin paint weak solvent type (large "Epool Smile" (manufactured by Nippon Paint Co., Ltd.) was applied to the paint so that the dry film thickness was 55 to 65 μm. Earth spray paint, dry for 1 day at 23℃ 50% relative humidity, then store at 50℃ for 7 days The resulting base was dried under atmospheric conditions to obtain a base coat. The dry film thickness on the resulting base coat was 50 to 70 μm. The coating material prepared in the above <Preparation Example of Coating Composition> was applied using an applicator as shown in FIG. The plate was dried for 7 days in an environment of 23°C and 50% relative humidity to obtain a coated plate.

[0080] <Coating film preparation method 3> The paint prepared in the above <Preparation Example of Paint Composition> was applied to a sandblasted board (3.2 x 70 x 1 50 mm) and the dry film thickness was 55-65 μm. The coated plate was dried for 7 days in a 0% relative humidity environment to obtain a coated plate. Painted with paint and sealed.

[0081] <Elasticity modulus> From the coated plate prepared by coating method 1, a strip of coating film measuring 50 mm x 10 mm was used as a test piece. After cutting out the specimen, the specimen was subjected to a test at a speed of 5 mm / min under an environment of 23°C and 50% humidity. A tensile test is performed under the above conditions, and the slope (proportionality constant) within the range in which stress and strain are proportional is determined. Elastic modulus (N / mm 2 The results are shown in Table 3.

[0082] <Gel fraction> From the coated plate prepared by coating method 1, a strip of coating film measuring 20 mm x 50 mm was used as a test piece. The mass (W0) of the resulting coating film (test piece) was measured, and the coating film (test piece) The sample was immersed in tetrahydrofuran (THF) at 23°C for one day. After immersion, it was taken out of the THF. The removed coating film (test piece) was washed with THF, then completely dried, and its mass (Wd) was The gel fraction was calculated from the following formula and evaluated based on the following criteria. The results are shown in Table 3. As shown in. Calculation formula: Gel fraction = 100-(W0-Wd) / W0 x 100 (standard) 〇: 85% or more △: 80% or more, less than 85% ×: Less than 80%

[0083] <Solvent Residual Rate> The mass (W) of the coating film on the coated plate prepared by coating film preparation method 1 and the paint used to prepare the coating film The mass of the coating (W0) is measured, and the theoretical coating mass when completely dry (Wz ) was calculated, and the remaining amount of solvent was calculated according to the following calculation formula, and evaluated based on the following criteria. The results are shown in Table 3. Calculation formula: remaining amount of solvent = (W-Wz) / W0 x 100 (standard) ○: Less than 6.0% △: 6.0% or more, less than 8.0% ×: 8.0% or more

[0084] <Adhesion> The coating surface of the coated plate prepared by coating method 2 (test) was measured under an environment of 23°C and 50% RH. Using a cutter knife, cut the test surface at 5mm intervals vertically and horizontally so as to reach the base material. Nine grids were created by cutting four lines each. A crease was made on one side of the grid surface. Press the tape firmly against the surface and pull it off forcefully at an angle of 60 to 90 degrees to remove the remaining coating. The adhesion of the coating was evaluated according to the following criteria based on the area of ​​the remaining coating. The results are shown in Table 3. If the area is equivalent to four or more squares, the coating has excellent adhesion. (standard) ◎: The area of ​​the remaining coating film corresponds to 8 or more squares. ○: The area of ​​the remaining coating film corresponds to 6 or more but less than 8 squares. △: The area of ​​the remaining coating film corresponds to 4 or more but less than 7 squares. ×: The area of ​​the remaining coating film corresponds to less than 4 squares.

[0085] <Corrosion resistance> The lower half of the coating on the plate prepared using coating method 3 was cut with a cutter knife. Test pieces were prepared by making cuts that reached the blasted plate (base material). The condition of rust and blisters was evaluated after 336 hours of neutral salt spray testing of 2371. The evaluation criteria are as follows, and the results are shown in Table 3. Rust and blister width at the cut part are 3 mm or less. If it is within this range, the coating film has excellent corrosion resistance. (standard) ○: Rust and swelling width of cut area is less than 2mm △: Rust / bulge width of cut area is greater than 2mm and less than 3mm ×: Rust or blister width in cut area is 3mm or more, or abnormality is found in general area

[0086] [Table 1]

[0087] [Table 2]

[0088] [Table 3]

Claims

1. (A) an epoxy resin, (B) a resin that reacts with the epoxy resin, (C) a pigment, and (D) water. A two-liquid water-based paint composition comprising the above composition, and applying the composition under conditions of 23°C and 50% humidity. The elastic modulus of the coating film after drying for 7 days under ２ The coating composition.

2. The coating composition was applied and dried at 23°C and 50% humidity for 7 days. The coating composition according to claim 1, characterized in that the ratio is 80% or more.

3. The coating composition was applied and dried at 23°C and 50% humidity for 7 days.

3. The coating composition according to claim 1, wherein the residual amount is less than 8.0%.

4. The resin (B) that reacts with the epoxy resin is at least a modified polyamide having a cyclic structure.

3. The coating composition according to claim 1, further comprising amine.

5. The resin (B) that reacts with the epoxy resin is at least a modified polyamide having a cyclic structure. (B) a modified polyimide having a cyclic structure that is contained in the resin that reacts with the epoxy resin; Claim 1 or 2, characterized in that the content of triamine is 50 to 100 mass%. The coating composition according to claim 1.

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