Quick-drying and corrosion-resistant two-component aqueous coating composition and coated substrate

Abstract

The invention discloses a quick-drying and corrosion-resistant two-component water-based coating composition which comprises a first component and a second component, the first component comprises epoxy resin, the second component comprises an amine curing agent, and the amine curing agent comprises (a) a part containing primary amine and / or secondary amine, (b) an epoxy part and (c) a part containing tertiary amine. Also disclosed is a coated substrate comprising a substrate and the two-component aqueous coating composition applied to at least a portion of the substrate.

Description

Fast-drying and corrosion-resistant two-component water-based coating composition and coated substrate

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese invention patent application No. 202310277843.5, entitled “Quick-drying and corrosion-resistant two-component aqueous coating composition,” filed on March 21, 2023, which is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention relates to the field of coatings, and in particular to a two-component water-based coating composition and a coated substrate. Background Art

[0004] As China's environmental protection requirements become increasingly stringent, the use of solvent-based coatings is increasingly restricted, and the market demand for water-based coatings continues to expand. However, the performance of currently available water-based coatings is insufficient, failing to match that of solvent-based coatings. Therefore, improving the performance of water-based coatings is currently a hot topic in the coatings industry.

[0005] For being used as two-component water-based paint such as primer, performance requirements mainly include quick-drying property, good moisture resistance and corrosion resistance. However, the prior art methods cannot meet these performance requirements simultaneously. Therefore, it is desirable to develop a two-component water-based paint having excellent overall properties, for example, quick-drying property, moisture resistance, corrosion resistance etc.

[0006] Summary of the Invention

[0007] The present inventors have conducted extensive research and developed a two-component waterborne coating composition having excellent comprehensive properties, such as quick drying, moisture resistance, corrosion resistance, etc.

[0008] The present invention provides a two-component waterborne coating composition, comprising a first component and a second component, wherein the first component comprises an epoxy resin, and the second component comprises an amine curing agent, wherein the amine curing agent comprises: (a) a portion containing a primary amine and / or a secondary amine, (b) an epoxy portion, and (c) a portion containing a tertiary amine.

[0009] The present invention also provides a coated substrate, comprising a substrate and the above two-component water-based coating composition coated on at least a portion of the substrate. DETAILED DESCRIPTION

[0010] In this application, unless expressly stated otherwise, the use of the singular includes the plural and the plural includes the singular. For example, although reference is made herein to "a" resin, one or more of the material may be used.

[0011] Throughout this application, the terms "comprise," "include," and "contain" are not intended to limit the invention to exclude any variations or additions. Furthermore, although the present invention has described coating compositions, methods of preparation, and the like using terms such as "comprising," the coating compositions, methods of preparation, and the like described herein may also be described as "consisting essentially of" or "consisting of." In this context, "consisting essentially of" means that any additional ingredients do not materially affect the properties of the coating formed from the coating composition.

[0012] In this application, unless otherwise expressly stated, the use of "or" means "and / or", even though "and / or" may be explicitly used in certain circumstances. In addition, it should be understood that any numerical range listed herein is intended to include all subranges contained therein. For example, a range of "1 to 10" is intended to include all subranges between the recited minimum value of 1 and the recited maximum value of 10 (including the end values), that is, all subranges having a minimum value equal to or greater than 1 and a maximum value equal to or less than 10.

[0013] Except as provided in the Examples or where otherwise explicitly stated, all numerical values ​​used in the specification and claims, representing quantities of ingredients, etc., should be interpreted as varying in all instances according to the term "about." Therefore, unless otherwise indicated, the numerical parameters listed in the following specification and claims are approximate and may vary depending on the desired performance of the present invention. At the very least, this is not intended to limit the application of the doctrine of equivalents to the scope of the claims. Each numerical parameter should at least be interpreted in terms of significant figures and subjected to ordinary rounding.

[0014] Although the numerical ranges and parameters setting forth the broad scope of the invention are approximate, the numerical values ​​set forth in the specific examples are reported as accurately as possible. However, any numerical value inherently has certain errors which are the inevitable result of the standard deviation obtained in its respective measurement methods.

[0015] As described above, the present invention relates to a two-component waterborne coating composition comprising a first component and a second component, wherein the first component comprises an epoxy resin, and the second component comprises an amine curing agent, wherein the amine curing agent comprises: (a) a portion containing a primary amine and / or a secondary amine, (b) an epoxy portion, and (c) a portion containing a tertiary amine.

[0016] In this article, the term "two-component coating (2K)", also known as two-pack coating or two-can coating, refers to a coating that contains two components packaged separately and then mixed in an accurate proportion to cure into a film before use.

[0017] As used herein, the term "aqueous" means that the solvent of the coating composition may contain at least about 50 wt% water, for example, at least about 60 wt%, at least about 70 wt%, at least about 80 wt%, at least about 90 wt% or at least about 95 wt% water. The two-component waterborne coating composition according to the present invention may be a coating composition with a low VOC content. As used herein, the term "VOC (volatile organic compound)" refers to any organic compound having a boiling point less than or equal to about 250°C (about 482°F) measured at a standard atmospheric pressure of about 101.3 kPa. Organic solvents are generally the main source of VOCs; the term "low VOC content" refers to a VOC content of less than, for example, about 400 g / L, such as less than about 300 g / L, less than about 200 g / L or less than about 100 g / L, etc. In some embodiments, the VOC content (excluding water) of the water-based coating composition according to the present invention can be, for example, less than about 100 g / L, meeting the Chinese national environmental protection regulations for water-based coatings requiring a VOC of less than about 420 g / L. The VOC value can be determined by measuring the content of each organic compound component in the coating using gas chromatography and then adding the contents of each component.

[0018] Suitably, the two-component aqueous coating composition according to the present invention may be a thermosetting coating composition, i.e., the coating composition may irreversibly form a coating film upon curing, which does not melt upon reheating and does not dissolve in a solvent. In this context, the term "curing" means that at least a portion of the components of the coating composition may be polymerized and / or cross-linked, or may be dried to form a hardened coating film.

[0019] Suitably, the two-component aqueous coating composition according to the present invention can be cured at about 5° C. to about 80° C. Suitably, the two-component aqueous coating composition according to the present invention can be cured at room temperature, for example, at about 15° C. to about 30° C.

[0020] Suitably, the two-component waterborne coating composition according to the present invention can be quick-drying. Suitably, the coating composition can be tack-free at room temperature in about 5 minutes to about 20 minutes. As used herein, the term "tack-free," also known as surface dry, refers to a coating film that is not sticky when touched directly with a finger.

[0021] Suitably, the two-component aqueous coating composition according to the present invention can be used as a primer. As used herein, the term "primer" refers to a coating between a substrate and a color paint. The primer can be applied directly to the substrate. Alternatively, the primer can be applied to a substrate that has already contained a coating.

[0022] Suitably, the two-component aqueous coating composition according to the present invention may have a solid content of about 40 to 60 wt%. As used herein, the "solid content" of a coating composition refers to the ratio of the mass remaining after drying and evaporation of the coating composition to the total mass of the composition.

[0023] Suitably, in the two-component waterborne coating composition of the present invention, the epoxy resin used for the first component may include a polymer containing two or more epoxy groups in the molecule. The epoxy group content in the epoxy resin can be expressed by epoxy equivalent. As used herein, the term "epoxy equivalent" refers to the mass grams of epoxy resin containing 1 gram equivalent of epoxy groups. Suitably, the epoxy resin can have an epoxy equivalent of about 450 to 550 g / eq. For example, the epoxy resin can have an epoxy equivalent of, for example, about 450 to 530 g / eq, about 480 to 530 g / eq, about 480 to 500 g / eq, or within the range of any other combination of these end values, for example, an epoxy equivalent of about 480 g / eq, an epoxy equivalent of about 500 g / eq, or an epoxy equivalent of about 530 g / eq.

[0024] Suitably, the epoxy resin may have a hydroxyl value of about 50 to 200 mgKOH / g. As used herein, the term "hydroxyl value" refers to the number of milligrams of potassium hydroxide (KOH) equivalent to the hydroxyl groups in 1 gram of resin. For example, the epoxy resin may have a hydroxyl value of about 50 to 180 mgKOH / g, a hydroxyl value of about 50 to 160 mgKOH / g, a hydroxyl value of about 80 to 160 mgKOH / g, a hydroxyl value of about 80 to 140 mgKOH / g, a hydroxyl value of about 80 to 120 mgKOH / g, a hydroxyl value of about 80 to 100 mgKOH / g, or within any other combination range using these end values, for example, a hydroxyl value of about 100 mgKOH / g, a hydroxyl value of about 120 mgKOH / g, a hydroxyl value of about 140 mgKOH / g, a hydroxyl value of about 160 mgKOH / g, or a hydroxyl value of about 180 mgKOH / g.

[0025] In the two-component waterborne coating composition according to the present invention, the epoxy resin having an appropriate epoxy equivalent and hydroxyl value can provide crosslinking points required for crosslinking with the curing agent, so that the coating has excellent resistance and various mechanical properties, and imparts polarity to the coating, thereby enhancing the adhesion between the coating and the substrate.

[0026] Suitably, the epoxy resin may be in the form of an emulsion. The epoxy resin emulsion may have a solid content of about 45 to 60 wt%. As used herein, the "solid content" of an emulsion refers to the percentage of the mass remaining after evaporation to the mass of the original emulsion.

[0027] Suitably, the epoxy resin may be greater than about 10 wt %, suitably at least about 15 wt %, suitably at least about 20 wt %, and / or up to about 35 wt %, such as up to about 30 wt %, suitably up to about 25 wt %, based on the total weight of the first component. For example, the epoxy resin may be about 10-35 wt %, suitably about 15-30 wt %, such as about 20-25 wt %, based on the total weight of the first component, or within any other range combining these values.

[0028] Suitably, in the two-component waterborne coating composition of the present invention, the amine curing agent for the second component can react with the above-mentioned epoxy resin to form a cross-linked film. Suitably, the amine curing agent may include: (a) a portion containing a primary amine and / or a secondary amine, (b) an epoxy portion, and (c) a portion containing a tertiary amine. The (a) portion containing a primary amine and / or a secondary amine may contain a primary amine and / or a secondary amine group; the (b) epoxy portion may contain an epoxy group; and the (c) portion containing a tertiary amine may contain a collection of monomers (or repeating units) containing tertiary amines in the amine curing agent.

[0029] Suitably, the portion (c) containing tertiary amines may be about 3-10 wt % based on the total solid weight of the amine curing agent. For example, the portion (c) containing tertiary amines may be about 4-10 wt %, about 5-10 wt %, about 6-10 wt %, about 6-9 wt %, about 6-8 wt %, about 6-7 wt % based on the total solid weight of the amine curing agent, or any other combination thereof, such as about 4 wt %, about 5 wt %, about 6 wt %, about 7 wt %, about 8 wt % or about 9 wt %, etc. As used herein, the total solid weight of the amine curing agent refers to the mass remaining after the solvent is dried and evaporated.

[0030] Suitably, the amine curing agent may have a branched structure comprising a main chain and at least one side chain. Suitably, the (a) portion containing a primary amine and / or secondary amine and the (b) epoxy portion may be located on the main chain to form a block structure. Suitably, the (c) portion containing a tertiary amine may be located on a side chain.

[0031] Alternatively, the amine curing agent may have a linear structure. Suitably, in the amine curing agent, (a) the portion containing a primary amine and / or a secondary amine may be located at at least one end of the main chain. For example, in the amine curing agent, (a) the portion containing a primary amine and / or a secondary amine may be located at both ends of the main chain.

[0032] Suitably, the amine curing agent may further include other hydrophilic and / or hydrophobic moieties to adjust the hydrophilicity of the amine curing agent. The hydrophilicity of the amine curing agent can be represented by an HLB value (hydrophilic-hydrophobic balance). Suitably, the HLB value of the amine curing agent may be about 5 to 15. For example, the HLB value of the amine curing agent may be about 6 to 15, about 7 to 15, about 8 to 15, about 8 to 14, about 8 to 13, about 8 to 12, or within any other combination of these end values, for example, about 6, about 7, about 8, about 9, about 10, about 11, about 12, about 13, or 14.

[0033] Suitably, the other hydrophilic and / or hydrophobic moieties may be different from the above-mentioned (a), (b) and (c) moieties. Suitably, the other hydrophilic and / or hydrophobic moieties may be blocks in the backbone or linear structure. Suitably, the hydrophilic moiety may comprise a polyether unit. Suitably, the hydrophobic moiety may comprise an aromatic unit and / or an aliphatic unit.

[0034] Suitably, the (b) epoxy moiety may comprise a bisphenol A type epoxy unit, ie, a unit obtainable by polymerization of bisphenol A and epichlorohydrin. The (b) epoxy moiety may improve the compatibility of the amine curing agent in the coating system of the present invention.

[0035] Suitably, in the above-mentioned amine curing agent, primary amine and / or secondary amine can provide active hydrogen. In the presence of a specific ratio of tertiary amine, primary amine and / or secondary amine can effectively react with the resin (e.g., epoxy resin) in the first component. In some examples, the active hydrogen equivalent of the amine curing agent can be about 300 to 400 g / eq. As used herein, the term "active hydrogen equivalent" refers to the number of hydrogens in the amine curing agent that can break hydrogen bonds when a chemical reaction occurs. For example, the active hydrogen equivalent of the amine curing agent can be about 320 to 380 g / eq, about 340 to 380 g / eq, about 340 to 360 g / eq, about 360 to 380 g / eq, or within any other combination range using these end values, for example, 320 g / eq, 340 g / eq, 360 g / eq, or 380 g / eq. In the amine curing agent, the source of active hydrogen can be primary amine and / or secondary amine.

[0036] Suitably, the amine curing agent may have a high molecular weight, thereby improving quick-drying properties while maintaining good compatibility. In some examples, the weight average molecular weight of the amine curing agent may be at least about 50,000, such as about 50,000 to 100,000. The weight average molecular weight may be determined by gel permeation chromatography using appropriate standards such as polystyrene standards. For example, the weight average molecular weight of the amine curing agent may be about 50,000 to 90,000, about 50,000 to 80,000, about 60,000 to 80,000, about 60,000 to 70,000, or within any other combination of these end values, for example, about 60,000, about 70,000, about 80,000, or about 90,000.

[0037] Suitably, the amine curing agent may be in the form of a self-emulsifying emulsion. As used herein, the term "self-emulsifying emulsion" refers to an emulsion of an amine curing agent that can be formed without the addition of an additional emulsifier. Suitably, the amine curing agent in the form of a self-emulsifying emulsion may have a solid content of about 30 to 40 wt%. As used herein, the "solid content" of a self-emulsifying emulsion refers to the percentage of the mass remaining after evaporation to the mass of the original emulsion. In the coating system of the present invention, the emulsion of the amine curing agent can exist stably, so that the service life of the coating composition is extended, drying is rapid, and excellent initial water resistance is imparted to the coating.

[0038] Suitably, the amine curing agent can be a commercially available product or prepared by methods known in the art, such as phase inversion. In some examples, the amine curing agent can be prepared, for example, by subjecting a polyamine compound, a low molecular weight epoxy resin, and a hydrophilic glycidyl ether to a chain extension reaction in a suitable solvent; adding an amine-containing reactive emulsifier during the reaction; terminating the reaction when a certain amine value or molecular weight is reached; and adding water dropwise with high-speed stirring to cause phase inversion, thereby preparing a water-dispersible curing agent emulsion. Various reactants suitable for use in the above-mentioned reaction are known in the art or can be purchased through commercial channels, and the present invention does not impose specific limitations thereon. In the above method, the polyamine compound is used to provide the primary amine, secondary amine and tertiary amine in the amine curing agent. Therefore, by selecting the type of polyamine compound having primary amine, secondary amine and tertiary amine and adjusting the dosage, the primary amine and / or secondary amine part of the amine curing agent and a specific content of the tertiary amine part can be obtained; the epoxy resin is used to react with the polyamine compound to provide the epoxy part in the amine curing agent, thereby improving the compatibility of the amine curing agent with the resin in the coating composition and increasing the molecular weight of the amine curing agent; the molecular weight of the amine curing agent can be controlled by adjusting the reaction endpoint.

[0039] Suitably, the amine curing agent may be at least about 15 wt %, suitably at least about 20 wt %, suitably at least about 25 wt %, and / or at most about 60 wt %, such as at most about 55 wt %, suitably at most about 50 wt %, based on the total weight of the second component. For example, the amine curing agent may be about 15-60 wt %, suitably 20-55 wt %, such as 25-50 wt %, based on the total weight of the second component, or within any other range combining these values.

[0040] Suitably, in the two-component water-based coating composition of the present invention, the solid weight ratio of the epoxy resin to the amine curing agent can be from about 3.5:1 to about 6:1. For example, the solid weight ratio of the epoxy resin to the amine curing agent can be from about 4:1 to about 5.5:1, from about 4.5:1 to about 5.5:1 or from about 5:1 to about 5.5:1 or within the range of any other combination of these end values, for example, it can be about 4:1, about 4.5:1, about 5:1 or about 5.5:1. The epoxy resin and the amine curing agent can effectively react to form a film, providing excellent performance. Therefore, the two-component water-based coating composition according to the present invention can be substantially free of a separate curing accelerator. As used herein, the separate curing accelerator refers to a compound that is independent of / free from the amine curing agent and can promote the crosslinking of the epoxy resin and the amine curing agent. A separate curing accelerator can have a relatively small molecular weight and is easily soluble, affecting the appearance of the coating, such as bubbling after being soaked in water or under hot and humid conditions. For example, the separate curing accelerator may include a tertiary amine compound, such as DMP-30 (2,4,6-tris(dimethylaminomethyl)phenol). The two-component aqueous coating composition according to the present invention may be substantially free of a separate tertiary amine compound. The separate tertiary amine compound may be different from the above-mentioned amine curing agent. As used herein, "substantially free of" a separate curing accelerator means that the content of the separate curing accelerator is less than about 0.1 wt % based on the total weight of the coating composition.

[0041] Suitably, in the two-component waterborne coating composition of the present invention, the first component may further comprise pigments and fillers. As used herein, the term "pigments and fillers" refers to materials that can provide color, effects, and / or functionality to the coating composition, including coloring pigments and fillers (also known as extenders).

[0042] Suitably, the pigments and fillers used in the first component may include anti-rust pigments. Suitably, the anti-rust pigments may include zinc phosphate, aluminum phosphate, and / or silica sol, etc. Suitably, the pigments and fillers used in the first component may also include carbon black, titanium dioxide, iron yellow, iron red, talc, mica powder, and / or barium sulfate. Suitably, the pigments and fillers used in the first component may include a combination of anti-rust pigments and talc and / or barium sulfate. Suitably, in the combination of anti-rust pigments and talc and / or barium sulfate, the weight ratio of the anti-rust pigments to the talc and / or barium sulfate may be from about 1:1 to about 1:7. For example, the weight ratio of the anti-rust pigment to the talc and / or barium sulfate can be about 1:1.5 to about 1:7, about 1:2 to about 1:7, about 1:2.5 to about 1:7, about 1:3 to about 1:7, about 1:3 to about 1:6.5, about 1:3 to about 1:6, about 1:3 to about 1:5.5, about 1:3 to about 1:5, or any other combination of these end values, for example, about 1:1.5, about 1:2, about 1:2.5, about 1:3, about 1:3.5, about 1:4, about 1:4.5, about 1:5, about 1:5.5, about 1:6, or about 1:6.5. By using a combination of the anti-rust pigment and talc and / or barium sulfate, the anti-rust pigment can passivate the metal substrate, and can further increase the density of the coating film when combined with talc and / or barium sulfate, thereby physically isolating the metal substrate from corrosion.

[0043] Suitably, the pigments and fillers may be greater than about 20 wt %, suitably at least about 25 wt %, suitably at least about 30 wt %, and / or up to about 55 wt %, such as up to about 50 wt %, and suitably up to about 45 wt %, based on the total weight of the first component. The pigments and fillers may be about 20-55 wt %, suitably about 25-50 wt %, such as about 30-45 wt %, based on the total weight of the first component, or within any other range combining these values.

[0044] Suitably, in the two-component waterborne coating composition of the present invention, the pigments and fillers may be substantially entirely present in the first component. In other words, in the two-component waterborne coating composition of the present invention, the second component may be substantially free of pigments and fillers. As used herein, "substantially free of" pigments and fillers means that the pigment and filler content of the second component is less than about 0.1 wt % based on the total weight of the second component.

[0045] Suitably, the two-component aqueous coating composition according to the present invention may have a pigment volume concentration (also known as PVC) of about 20 to 35. As used herein, the term "pigment volume concentration" refers to the volume ratio of pigments and fillers in a dry film formed from the coating composition to all non-volatile components in the coating composition, wherein the pigments and fillers may include color pigments and fillers (i.e., extender pigments), and all non-volatile components may include resin solids and pigments and fillers.

[0046] Suitably, in the two-component water-based coating composition of the present invention, the first component may further include a nonionic dispersant to promote compatibility of the various components in the water-based coating composition. The use of a nonionic dispersant in the two-component water-based coating composition of the present invention can avoid the epoxy ring opening that may occur during long-term storage due to the use of an ionic dispersant, which affects the stability and performance of the paint film after curing. In some examples, suitable nonionic dispersants may include, but are not limited to, ALLNEX ADDITOL VXW 6208 / 60, BYK 190, BYK 2080, OMG Borchers 1252, BASF 4550, and the like. Suitably, the dispersant may be about 0 to 5 wt %, for example, about 0.5 to 3 wt %, based on the total weight of the first component.

[0047] Suitably, in the two-component aqueous coating composition of the present invention, the first component may further include a defoamer. As used herein, the term "defoamer" refers to a substance that can inhibit the formation of bubbles and help the generated bubbles to escape or burst during the production process. Suitably, the defoamer may include a silicone defoamer. In some examples, suitable defoamers may include, but are not limited to, BYK-024, BYK022, BYK019, BASF FoamStar SI2299, Tego901W, Tego902W, etc. Suitably, based on the total weight of the first component, the defoamer may be about 0 to 2 wt%, for example, about 0.1 to 1.5 wt%.

[0048] Suitably, in the two-component waterborne coating composition of the present invention, the first component may further include a film-forming aid. As used herein, the term "film-forming aid" refers to a substance that can help lower the minimum film-forming temperature of the resin, improve film-forming properties, and increase the gloss of the paint film. In some examples, suitable film-forming aids may include, but are not limited to, DPNB, DPM, PPH, alcohol ester 12, and the like. Suitably, based on the total weight of the first component, the film-forming aid may be about 0 to 5 wt%, for example, about 0.5 to 3 wt%.

[0049] Suitably, the first component of the two-component waterborne coating composition of the present invention may further include a substrate wetting agent. As used herein, the term "substrate wetting agent" refers to a substance that can improve the surface tension and permeability of the waterborne coating composition, better wet the substrate, and improve the adhesion of the coating. Suitably, the substrate wetting agent can be present in an amount of about 0 to 2 wt %, such as about 0.1 to 1 wt %, based on the total weight of the first component.

[0050] Suitably, in the two-component waterborne coating composition of the present invention, the first component may further include a rheological thickener. As used herein, the term "rheological thickener" refers to a substance that can increase the viscosity of the coating, improve the wet film thickness, and protect the coating from sedimentation and stratification. In some examples, the thickener may include bentonite, fumed silica, and / or hydrophobically modified polyurethane, etc. Suitably, based on the total weight of the first component, the rheological thickener may be about 0 to 2 wt%, for example, about 0.1 to 1 wt%.

[0051] Suitably, in the two-component waterborne coating composition of the present invention, the first component may further comprise water. Suitably, the water may be in an amount of about 10 to 40 wt % based on the total weight of the first component.

[0052] Suitably, the first component of the two-component waterborne coating composition of the present invention may further include one or more other film-forming substances (e.g., resins other than the epoxy resin) to provide desired properties. In some examples, the first component of the two-component waterborne coating composition of the present invention may further include one or more other additives; such additives are suitable for waterborne coating systems, and the amount used can be determined by those skilled in the art based on the desired properties.

[0053] Suitably, in the two-component water-based coating composition of the present invention, the second component may further include one or more of the above-mentioned adjuvants or other adjuvants. The adjuvants used in the first component and the corresponding adjuvants used in the second component may be the same or different. For example, in the two-component water-based coating composition of the present invention, the second component may further include an appropriate amount of a film-forming aid to improve the film-forming properties without affecting the drying of the paint film. Based on the total weight of the second component, the film-forming aid may be about 0 to 2 wt%, for example, about 0.1 to 1 wt%.

[0054] Suitably, in the two-component waterborne coating composition of the present invention, the second component may further comprise water. Suitably, the water may be in an amount of about 10 to 40 wt % based on the total weight of the second component.

[0055] In some embodiments, the two-component water-based coating composition according to the present invention can be prepared by the following method:

[0056] I. Prepare the first component, comprising:

[0057] (1) grinding a mixture comprising pigments, fillers, additives, and solvents at a temperature of about <50° C. for about 1 to 2 hours to a maximum particle size of <about 15 μm;

[0058] (2) adding epoxy resin, additives, solvent, etc. to the mixture of step (1) at a temperature of about 10 to 40° C. and stirring for about 10 to 20 minutes;

[0059] II. Prepare the second component, comprising:

[0060] At a temperature of about 10 to 40° C., adding an amine curing agent, optional additives, and a solvent in steps, and stirring for about 10 to 20 minutes; and

[0061] III. At a temperature of about 10 to 40°C, mix the first component and the second component evenly.

[0062] Suitably, in the above step (1), the pigments, fillers, additives and solvents can be added to the container one by one and mixed, and the time interval between adding each material is about 1 to 5 minutes.

[0063] Suitably, in the above step (2), the epoxy resin, the auxiliary agent and the solvent can be added into the container one by one and mixed, and the time interval between adding each material is about 1 to 5 minutes.

[0064] Suitably, the first component and the second component can be mixed in a volume ratio of about 3.5: 1 to about 6: 1. For example, the volume ratio of the first component to the second component can be about 4: 1 to about 5.5: 1, about 5: 1 to about 5.5: 1, or any other combination of these values, for example, about 4: 1, about 4.5: 1, about 5: 1, or about 5.5: 1.

[0065] In other embodiments, the present invention also provides a coated substrate. The coated substrate may include a substrate and the above-mentioned two-component water-based coating composition applied on at least a portion of the substrate. The two-component water-based coating composition may be directly applied to an uncoated substrate. Alternatively, the water-based coating composition may be applied to a coated substrate. Suitably, the substrate may include a metal, for example, a metal substrate. Suitably, the substrate may be part of an industrial plant, a vehicle, or a building steel structure.

[0066] Suitably, the two-component aqueous coating composition according to the present invention can be applied by methods known to those skilled in the art, such as electrocoating, spraying, electrostatic spraying, dipping, roller coating, brushing, etc., and then cured to form a coating.

[0067] Suitably, the two-component aqueous coating composition according to the present invention can be cured at a temperature of about 5° C. to about 80° C. Suitably, the aqueous coating composition according to the present invention can be cured at room temperature, for example, at a temperature of about 15 to 30° C. Suitably, the two-component aqueous coating composition according to the present invention can be tack-free at room temperature in about 5 to 20 minutes.

[0068] Suitably, the two-component aqueous coating composition according to the present invention can form a coating having a dry film thickness of about 30 μm to about 150 μm. As used herein, the term "dry film thickness" is the thickness of the coating composition after it is fully cured.

[0069] In other embodiments, the present invention further provides use of the two-component aqueous coating composition for coating a substrate.

[0070] Example

[0071] The following examples are provided to further illustrate the present invention but should not be construed as limiting the invention to the details described in the examples. Unless otherwise indicated, all parts and percentages in the following examples are by weight.

[0072] The two-component aqueous coating compositions Ex1, Ex2 and Ex3 according to the present invention were prepared using the materials and amounts listed in Table 1 below:

[0073] (1) adding materials 1 to 6 of the first component into a container one by one and mixing at a temperature of about 10 to 40° C., with the time interval between adding each material being about 1 to 5 minutes;

[0074] (2) grinding materials 1 to 6 in the first component at a temperature of about <50° C. for about 1 to 2 hours to a maximum particle size of <15 μm;

[0075] (3) adding materials 7 to 11 of the first component into the container one by one at a temperature of about 10 to 40° C., mixing them with the time interval of adding each material being about 1 to 5 minutes, and then stirring for 10 to 20 minutes;

[0076] (4) adding materials 1 to 3 of the second component step by step at a temperature of about 10 to 40° C. and stirring for 10 to 20 minutes; and

[0077] (5) At a temperature of about 10-40° C., mix the first component and the second component uniformly, with the volume ratio of the first component to the second component being 5 / 1.

[0078] Table 1. Two-component aqueous coating compositions Ex1, Ex2 and Ex3 according to the present invention

[0079] Note:

[0080] a Allnex ADDITOL VXW 6208;

[0081] b talc and barium sulfate;

[0082] cHEUCOPHOS ZPA;

[0083] d Selected from titanium white, iron yellow, iron red, and / or carbon black;

[0084] e BYK024;

[0085] f Aqueous epoxy emulsion with a solid content of 50-60 wt%, an epoxy equivalent weight of 450-550 g / eq, and a hydroxyl value of 50-200 mgKOH / g;

[0086] g Selected from BYK348, and / or TEGO TWIN 4100;

[0087] h Selected from DPNB, and / or DPM;

[0088] i DOW ACRYSOL RM-12W and / or ACRYSOL RM-2020;

[0089] j An amine curing agent emulsion has a solid content of about 30-40 wt%. The amine curing agent includes (a) a portion containing primary amines and / or secondary amines, (b) an epoxy portion, and 3-10 wt% of (c) a portion containing tertiary amines. The HLB value is 5-15, the active hydrogen equivalent can be 300-400 g / eq, and the weight-average molecular weight is at least 50,000.

[0090] Comparative Example:

[0091] The two-component aqueous coating compositions CE1, CE2 and CE3 of the comparative examples were prepared using the materials and amounts listed in Table 2 below:

[0092] (1) adding materials 1 to 6 of the first component into a container one by one and mixing at a temperature of about 10 to 40° C., with the time interval between adding each material being about 1 to 5 minutes;

[0093] (2) grinding materials 1 to 6 in the first component at a temperature of about <50° C. for about 1 to 2 hours to a maximum particle size of <15 μm;

[0094] (3) adding materials 7 to 11 of the first component into the container one by one at a temperature of about 10 to 40° C., mixing them with the time interval of adding each material being about 1 to 5 minutes, and then stirring for 10 to 20 minutes;

[0095] (4) adding materials 1 to 3 of the second component step by step at a temperature of about 10 to 40° C. and stirring for 10 to 20 minutes; and

[0096] (5) At a temperature of about 10-40° C., mix the first component and the second component uniformly, with the volume ratio of the first component to the second component being 5 / 1.

[0097] Table 2. Comparative Examples of Two-Component Waterborne Coating Compositions CE1, CE2, and CE3

[0098] Note:

[0099] a Allnex ADDITOL VXW 6208;

[0100] b talc and barium sulfate;

[0101] c HEUCOPHOS ZPA;

[0102] d Selected from titanium white, iron yellow, iron red, and / or carbon black;

[0103] e BYK024;

[0104] f Aqueous epoxy emulsion with a solid content of 50-60 wt%, an epoxy equivalent weight of 450-550 g / eq, and a hydroxyl value of 50-200 mgKOH / g;

[0105] g Selected from BYK348, and / or TEGO TWIN 4100;

[0106] h Selected from DPNB, and / or DPM;

[0107] i DOW ACRYSOL RM-12W;

[0108] j1 Huntsman 3986;

[0109] j2 Hexion 8530; and

[0110] j3 ALLNEX 2188.

[0111] The two-component aqueous coating compositions CE4, CE5 and CE6 of the comparative examples were prepared using the materials and amounts listed in Table 3 below:

[0112] (1) adding materials 1 to 6 of the first component into a container one by one and mixing at a temperature of about 10 to 40° C., with the time interval between adding each material being about 1 to 5 minutes;

[0113] (2) grinding materials 1 to 6 in the first component at a temperature of about <50° C. for about 1 to 2 hours to a maximum particle size of <15 μm;

[0114] (3) adding materials 7 to 11 of the first component into the container one by one at a temperature of about 10 to 40° C., mixing them with the time interval of adding each material being about 1 to 5 minutes, and then stirring for 10 to 20 minutes;

[0115] (4) adding materials 1 to 3 of the second component step by step at a temperature of about 10 to 40° C. and stirring for 10 to 20 minutes; and

[0116] (5) At a temperature of about 10-40° C., mix the first component and the second component uniformly, with the volume ratio of the first component to the second component being 5 / 1.

[0117] Table 3. Comparative Example Two-Component Waterborne Coating Compositions CE4, CE5, and CE6

[0118] Note:

[0119] a Allnex ADDITOL VXW 6208;

[0120] b talc and barium sulfate;

[0121] c HEUCOPHOS ZPA;

[0122] d Selected from titanium white, iron yellow, iron red, and / or carbon black;

[0123] e BYK024;

[0124] f Aqueous epoxy emulsion with a solid content of 50-60 wt%, an epoxy equivalent weight of 450-550 g / eq, and a hydroxyl value of 50-200 mgKOH / g;

[0125] g Selected from BYK348, and / or TEGO TWIN 4100;

[0126] h Selected from DPNB, and / or DPM;

[0127] iDOW ACRYSOL RM-12W;

[0128] j1 Huntsman 3986;

[0129] j2 Hexion 8530;

[0130] j3 ALLNEX 2188; and

[0131] k DMP-30.

[0132] The materials and amounts listed in Table 4 below were used to prepare a two-component aqueous coating composition CE7 of the comparative example:

[0133] (1) adding materials 1 to 6 of the first component into a container one by one and mixing at a temperature of about 10 to 40° C., with the time interval between adding each material being about 1 to 5 minutes;

[0134] (2) grinding materials 1 to 6 in the first component at a temperature of about <50° C. for about 1 to 2 hours to a maximum particle size of <15 μm;

[0135] (3) adding materials 7 to 11 of the first component into the container one by one at a temperature of about 10 to 40° C., mixing them with the time interval of adding each material being about 1 to 5 minutes, and then stirring for 10 to 20 minutes;

[0136] (4) adding materials 1 to 3 of the second component step by step at a temperature of about 10 to 40° C. and stirring for 10 to 20 minutes; and

[0137] (5) At a temperature of about 10-40° C., mix the first component and the second component uniformly, with the volume ratio of the first component to the second component being 5 / 1.

[0138] Table 4. Comparative Example Two-Component Waterborne Coating Composition CE7

[0139] Note:

[0140] a Ionic dispersant: BYK151;

[0141] b talc and barium sulfate;

[0142] c HEUCOPHOS ZPA;

[0143] d Selected from titanium white, iron yellow, iron red, and / or carbon black;

[0144] e BYK024;

[0145] f Aqueous epoxy emulsion with a solid content of 50-60 wt%, an epoxy equivalent weight of 450-550 g / eq, and a hydroxyl value of 50-200 mgKOH / g;

[0146] g Selected from BYK348, and / or TEGO TWIN 4100;

[0147] h Selected from DPNB, and / or DPM;

[0148] i DOW ACRYSOL RM-12W and / or ACRYSOL RM-2020;

[0149] j An amine curing agent emulsion has a solid content of about 30-40 wt%. The amine curing agent includes: (a) a portion containing primary amines and / or secondary amines, (b) an epoxy portion, and 3-10 wt% of (c) a portion containing tertiary amines. The HLB value is 5-15, the active hydrogen equivalent can be 300-400 g / eq, and the weight-average molecular weight is at least 50,000.

[0150] Performance testing:

[0151] First, the two-component waterborne coating composition Ex1-3 prepared as above and the comparative coating composition CE1-7 were applied to a metal substrate, baked at 80° C. for 30 minutes, and then left at room temperature for 7 days.

[0152] Then, the coated substrates were subjected to the following performance tests:

[0153] 1-Sag: Determine the dry film thickness that does not sag after spraying with the TU4 viscosity cup in 40-50 seconds.

[0154] 2-Salt spray resistance: Conduct salt spray resistance test according to GB / T 1771 standard to determine the corrosion width after 1000 hours. Test requirement: The corrosion width after 1000 hours is <2mm.

[0155] 3. Moisture and Heat Resistance: Conduct a moisture and heat resistance test according to GB / T 1740 to observe whether the coating shows any blistering, rusting, or shedding after 1000 hours. Test requirement: After 1000 hours, the coating must show no blistering, rusting, or shedding.

[0156] The two-component waterborne coating compositions Ex1-3 and comparative coating compositions CE1-7 prepared above were coated on 8 mm thick metal substrates, allowed to air dry at room temperature for 4 to 6 hours, and then tested for quick-drying properties of the coatings.

[0157] 4-Quick drying: Use 280 grit sandpaper for polishing, and it should be able to be polished without getting stuck to the sandpaper.

[0158] The two-component waterborne coating compositions Ex1-3 and comparative coating compositions CE1-7 prepared above were applied to metal substrates, allowed to air dry at room temperature for 24 hours, and then the initial water resistance of the coatings was tested.

[0159] 5- Initial Water Resistance: After soaking the coating in water for 96 hours, observe whether the coating has any blistering or peeling. Test requirement: After soaking in water for 96 hours, the coating has no blistering or peeling.

[0160] Table 5. Test results of Ex1, Ex2 and Ex3

[0161] Table 6. Test results for CE1, CE2, CE3, CE4, CE5, CE6, and CE7

[0162] While particular aspects of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various other changes and modifications may be made without departing from the spirit and scope of the invention. It is therefore intended that the appended claims cover all such changes and modifications as fall within the scope of the invention.

Claims

1. A two-component water-based coating composition, comprising a first component and a second component, wherein The first component includes epoxy resin, The second component includes an amine curing agent, wherein the amine curing agent includes: (a) a primary and / or secondary amine containing moiety, (b) an epoxy moiety, and (c) a tertiary amine containing moiety.

2. The coating composition according to claim 1, wherein the portion (c) containing the tertiary amine accounts for 3 to 10 wt% of the total solid weight of the amine curing agent.

3. The coating composition according to claim 2 or 3, wherein the active hydrogen equivalent of the amine curing agent is 300 to 400 g / eq.

4. The coating composition according to any one of claims 1 to 3, wherein the weight average molecular weight of the amine curing agent is 50,000 to 100,000.

5. The coating composition according to any one of claims 1 to 4, wherein the amine curing agent further comprises other hydrophilic parts and / or hydrophobic parts for adjusting the hydrophilicity of the amine curing agent, so that the HLB value of the amine curing agent can be 5 to 15.

6. The coating composition according to any one of claims 1 to 5, wherein the amine curing agent is in the form of a self-emulsifying emulsion.

7. The coating composition according to any one of claims 1 to 6, wherein the amine curing agent has a branched structure comprising a main chain and at least one branch chain.

8. The coating composition according to claim 7, wherein (a) the portion containing primary amine and / or secondary amine and (b) the epoxy portion in the amine curing agent are located on the main chain to form a block structure.

9. The coating composition according to claim 7 or 8, wherein the portion containing a tertiary amine in (c) the amine curing agent is located on a side chain.

10. The coating composition according to any one of claims 1 to 6, wherein the amine curing agent has a linear structure.

11. The coating composition according to any one of claims 1 to 10, wherein the epoxy resin has an epoxy equivalent weight of 450 to 550 g / eq.

12. The coating composition according to any one of claims 1 to 11, wherein the epoxy resin has a hydroxyl value of 50 to 200 mgKOH / g.

13. The coating composition of any one of claims 1 to 12, wherein the solid weight ratio of the epoxy resin to the amine curing agent is 3.5:1 to 6:

1.

14. The coating composition of any one of claims 1 to 13, wherein the coating composition is substantially free of a separate curing accelerator.

15. The coating composition of claims 1-14, wherein the coating composition is substantially free of separate tertiary amine compounds.

16. The coating composition according to any one of claims 1 to 15, wherein the first component comprises pigments and fillers, and the pigments and fillers comprise anti-rust pigments and talc and / or barium sulfate.

17. The coating composition of any one of claims 1 to 16, wherein the second component is substantially free of pigments or fillers.

18. The coating composition of any one of claims 1-17, wherein the first component comprises a nonionic dispersant.

19. The coating composition according to any one of claims 1 to 18, wherein the coating composition can be tack-dried at room temperature in 5 to 20 minutes.

20. A coated substrate comprising a substrate and a coating composition according to claims 1 to 19 applied to at least a portion of the substrate.

21. The coated substrate of claim 20, wherein the substrate comprises a metal.

22. The coated substrate of claim 20 or 21, wherein the substrate is part of: industrial equipment, a vehicle, or a building steel structure.