Waterborne epoxy anticorrosive paint of biomass phenol modified graphene oxide and preparation method of waterborne epoxy anticorrosive paint

Abstract

The invention discloses a waterborne epoxy anticorrosive coating of biomass phenol modified graphene oxide and a preparation method of the waterborne epoxy anticorrosive coating. The coating is composed of a component A and a component B, wherein the component A comprises a waterborne epoxy emulsion, biomass phenol modified graphene oxide, a pigment filler, an auxiliary agent and water; and the component B is a waterborne epoxy curing agent. A coating formed by the paint has excellent corrosion resistance, and is suitable for primer protection in the industrial fields of steel structures, mechanical equipment and the like.

Description

Technical Field

[0001] This invention belongs to the field of chemical coating technology, specifically relating to a waterborne epoxy anticorrosive coating of biomass phenol-modified graphene oxide and its preparation method. Background Technology

[0002] With increasingly stringent requirements for metal corrosion protection, graphene and its derivatives, due to their unique two-dimensional sheet structure, high specific surface area, and excellent physical barrier properties, have shown broad application prospects in the field of anti-corrosion coatings. Graphene oxide (GO) is rich in oxygen-containing functional groups such as hydroxyl, epoxy, and carboxyl groups, which not only endow it with good hydrophilicity and dispersion potential but also provide the possibility for interfacial bonding between it and the polymer matrix. Introducing GO into coating systems can effectively extend the penetration path of corrosive media, improve the physical barrier performance of the coating, and enhance its corrosion resistance life.

[0003] Currently, several patents disclose the modification and application of graphene in anti-corrosion coatings. For example: CN118755347A proposes a graphene composite material EP@DA@GO@M modified with dopamine and 1,6-hexanediol diglycidyl ether. This material utilizes the hydrogen bonding and electronic coupling between the catechol structure of dopamine and GO and the corrosion inhibitor to construct an anti-corrosion coating with dual functions of "physical shielding and chemical slow release." Although this coating exhibits excellent anti-corrosion performance, the high cost of dopamine and the cumbersome synthesis process limit its large-scale application.

[0004] CN114539877B reports an anti-corrosion coating based on phytic acid and divalent zinc ions modified graphene oxide. Phytic acid and Zn(II) are loaded onto the GO surface through electrostatic self-assembly, utilizing the film-forming properties of phytic acid and the corrosion-inhibiting effect of Zn²⁺ to improve the coating's self-healing ability and corrosion resistance. However, in this method, phytic acid easily forms precipitates with metal ions, affecting the dispersion stability of graphene.

[0005] CN108559361B discloses a graphene composite coating based on intercalation modification of tannic acid (TA) and silane coupling agent KH560. The intercalation dispersion is achieved through the π-π conjugation between tannic acid and graphene, and KH560 is used to enhance the bonding force between graphene and epoxy resin, thereby improving the corrosion resistance of the coating. However, in this method, tannic acid only acts as an intercalating molecule, and the tannic acid content in the modified graphene is relatively low, failing to fully utilize the structural characteristics of tannic acid.

[0006] In addition, existing graphene modification methods mostly rely on silane coupling agents, polymer coating, or organic amine modification. Although these methods improve dispersibility to some extent, they still have problems such as complex processes, high costs, and poor environmental compatibility. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a waterborne epoxy anticorrosive coating and its preparation method for biomass phenol-modified graphene oxide. The purpose of this invention is to significantly improve the dispersibility and interfacial compatibility of graphene oxide in a waterborne epoxy system by using a green and mild modification process with biomass phenolic compounds to modify the surface of the graphene oxide, thereby obtaining an anticorrosive coating with excellent physical shielding and corrosion resistance.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows: A coating is composed of two components, A and B. The first component comprises an aqueous epoxy emulsion, biomass phenol-modified graphene oxide, pigments and fillers, additives, and water; Component B is a water-based epoxy curing agent.

[0009] According to an embodiment of the present invention, the A component comprises, by weight: 30-70 parts of aqueous epoxy emulsion, 0.5-10 parts of biomass phenol-modified graphene oxide, 10-30 parts of pigments and fillers, and 10-40 parts of water. Preferably, by weight, component A comprises: 30-50 parts of aqueous epoxy emulsion, 0.5-6 parts of biomass phenol-modified graphene oxide, 10-30 parts of pigments and fillers, and 15-30 parts of water.

[0010] According to an embodiment of the present invention, the biomass phenols are selected from polyphenolic compounds or phenolic acid compounds, such as one or more of p-hydroxybenzoic acid, gallic acid, vanillic acid, protocatechuic acid, and tannic acid.

[0011] According to an embodiment of the present invention, the biomass phenolic modified graphene oxide is selected from one or more of gallic acid modified graphene oxide, vanillic acid and protocatechuic acid composite modified graphene oxide, and tannic acid modified graphene oxide.

[0012] According to an embodiment of the present invention, the biomass phenolic modified graphene oxide is prepared by the following method: dispersing graphene oxide in a buffer solution with pH 7.5 to 9.5, sonicating for 1 to 5 hours to form a dispersion with a concentration of 1 to 10 mg / mL; then adding biomass phenolic compounds, and reacting at 60 to 100°C for 6 to 24 hours; after the reaction is completed, centrifuging, washing, and drying are performed to obtain the biomass phenolic modified graphene oxide.

[0013] According to an embodiment of the present invention, the waterborne epoxy emulsion in component A is 30, 35, 40, 45, 50, 55, 60, 65 or 70 parts by weight.

[0014] According to an embodiment of the present invention, the solid content of the aqueous epoxy emulsion is 30-70%, for example 40%, 50%, or 60%.

[0015] According to an embodiment of the present invention, the biomass phenolic modified graphene oxide in component A is 0.5, 1, 1.5, 2, 3, 4, 5, 6, 7, 8, 9 or 10 parts by weight.

[0016] According to an embodiment of the present invention, the pigments and fillers in component A are 10, 15, 20, 25 or 30 parts by weight.

[0017] According to an embodiment of the present invention, the pigments and fillers are selected from one or both of titanium dioxide and light calcium carbonate.

[0018] According to an embodiment of the present invention, the water in component A is 10, 15, 20, 25, 30, 35 or 40 parts by weight.

[0019] According to an embodiment of the present invention, the water is deionized water.

[0020] According to embodiments of the present invention, the additives include, but are not limited to, one or more of dispersants, defoamers, leveling agents, and thickeners.

[0021] According to an embodiment of the present invention, the A component comprises 0.5 to 10 parts by weight, for example 1.0 to 8 parts, exemplarily 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 parts of an adjuvant.

[0022] According to some embodiments of the present invention, the additives include 0.5 to 3 parts of dispersant, 0.1 to 1 part of defoamer, 0.2 to 2 parts of leveling agent, and 0.1 to 2 parts of thickener.

[0023] According to some embodiments of the present invention, the dispersant is selected from polyether-modified styrene-maleic anhydride copolymer polymeric dispersants, the defoamer is selected from polyether-modified fatty acid ester composite defoamers, the leveling agent is selected from nonionic polyether-modified polysiloxane leveling agents, and the thickener is selected from waterborne polyurethane thickeners.

[0024] According to an embodiment of the present invention, the weight ratio of component B to the solid substance of the aqueous epoxy emulsion is (20~40):100, for example 25:100, 30:100, or 35:100.

[0025] According to an embodiment of the present invention, the waterborne epoxy curing agent is selected from nonionic amine adduct waterborne epoxy curing agents.

[0026] According to an embodiment of the present invention, the average particle size of the biomass phenol-modified graphene oxide, pigments, fillers, and / or additives does not exceed 50 μm.

[0027] The present invention also provides a method for preparing the coating, comprising the following steps: (1) Disperse water, biomass phenol-modified graphene oxide, additives (such as one or more of dispersants, defoamers, leveling agents and thickeners) and pigments and fillers at high speed, and then grind them to a fineness of ≤ 50 μm; (2) After step (1) is completed, add water-based epoxy emulsion and mix to obtain component A; (3) When using, mix component A and component B to obtain the coating.

[0028] According to an embodiment of the present invention, the preparation method of the biomass phenolic modified graphene oxide includes the following steps: dispersing graphene oxide in a buffer solution with pH 7.5 to 9.5, sonicating for 1 to 5 hours to form a dispersion with a concentration of 1 to 10 mg / mL; then adding a biomass phenolic compound and reacting at 60 to 100°C for 6 to 24 hours; after the reaction is completed, centrifuging, washing, and drying are performed to obtain the biomass phenolic modified graphene oxide. Furthermore, the concentration of the biomass phenols in the buffer solution is 0.05–4 mg / mL.

[0029] The present invention also provides a coating formed by curing the above-mentioned coating material.

[0030] According to an embodiment of the present invention, the coating has any one or more of the following properties: Pencil hardness ≥ 3; Flexibility ≤1mm; The resistance time to neutral salt spray is ≥420h, for example, 420h~550h; Acid resistance time ≥250h, for example 300h~800h; Salt water tolerance time ≥550h, for example 600h~1200h.

[0031] According to an embodiment of the present invention, the coating is a primer protective layer for steel structures, mechanical equipment, etc.

[0032] This invention also provides the application of the above-mentioned coating in the preparation of coatings, wherein the coating has any one or more of the following properties: Pencil hardness ≥ 3; Flexibility ≤1mm; The resistance time to neutral salt spray is ≥420h, for example, 420h~550h; Acid resistance time ≥250h, for example 300h~800h; Salt water tolerance time ≥550h, for example 600h~1200h.

[0033] The present invention has the following beneficial effects: The surface modification of graphene oxide is carried out using widely available, green, and renewable biomass phenolic compounds. The modification process is mild, easy to operate, and environmentally friendly.

[0034] Biomass phenolic compounds contain abundant catechol / pyrogallol groups and phenolic hydroxyl groups in their molecular structure. These polyphenolic structures can be oxidized and polymerized under weakly alkaline conditions, anchoring firmly to the surface and edges of graphene oxide sheets through covalent bonding, π-π stacking, and hydrogen bonding, forming a stable coating layer. This coating layer not only effectively prevents the recombination of graphene sheets and significantly improves their dispersion stability in aqueous systems, but also introduces a large number of active phenolic hydroxyl groups into the coating. These phenolic hydroxyl groups can form a strong hydrogen bond network with epoxy resin molecular chains, enhancing the interfacial bonding between modified graphene oxide and the resin matrix. The resulting coating / coating exhibits excellent corrosion resistance and is suitable as an anti-corrosion primer for industrial applications such as steel structures and mechanical equipment, showing promising application prospects. Detailed Implementation

[0035] The present invention will be further described below with reference to embodiments, but these are not intended to limit the scope of the invention. Unless otherwise specified, the raw materials involved in the following embodiments are all common products that can be purchased through conventional commercial channels.

[0036] Example 1: Waterborne epoxy anticorrosion coating and its preparation 1. Preparation of gallic acid-modified graphene oxide (GA-GO) 50 mg of graphene oxide (GO) was dispersed in 100 mL of Tris-HCl buffer at pH 8.5 and sonicated for 2 hours to form a homogeneous dispersion. Then, 0.5 mM gallic acid (GA) was added, and the mixture was stirred in an 85°C water bath for 12 hours to complete the polymerization of gallic acid on the GO surface. After the reaction, the mixture was centrifuged (10000 r / min, 10 min), and the precipitate was washed three times successively with deionized water and anhydrous ethanol. Finally, it was dried in a vacuum drying oven at 60°C for 6 hours to obtain gallic acid-modified graphene oxide (GA-GO).

[0037] 2. Preparation of component A of the coating Weigh each raw material according to the following proportions by weight: Deionized water: 20 parts GA-GO: 3 servings Dispersant (BYK-190): 1 part Defoamer (Foamex 830): 0.3 parts Leveling agent (BYK-333): 0.5 parts Thickener (XS 83): 0.5 parts Titanium dioxide: 15 parts Light calcium carbonate: 10 parts Waterborne epoxy emulsion (E51 type, solid content 50%): 30 parts Preparation process: Deionized water, GA-GO, dispersant, defoamer, leveling agent, thickener, and colorant are added. The fillers (titanium dioxide and light calcium carbonate) were sequentially added to a dispersion tank and dispersed at a high speed of 800 r / min for 30 minutes. The slurry was then transferred to a sand mill and ground until the fineness was ≤ 50 μm. Finally, an aqueous epoxy emulsion was added under low-speed stirring (300 r / min), mixed evenly, and filtered to obtain component A of the coating.

[0038] 3. Component B is a water-based epoxy curing agent (Banco 920). Component B is mixed with component A at a dosage of 30% of the solid content of the epoxy emulsion in component A to obtain a water-based epoxy anti-corrosion coating.

[0039] Example 2 Waterborne epoxy anticorrosion coating and its preparation 1. Preparation of vanillic acid / protocatechuic acid composite modified graphene oxide (VA / PCA-GO) 50 mg of graphene oxide (GO) was dispersed in 100 mL of Tris-HCl buffer at pH 8.5 and sonicated for 2 hours. Then, 0.3 mM vanillic acid (VA) and 0.3 mM protocatechuic acid (PCA) were added, and the mixture was stirred in an 80°C water bath for 18 hours. After the reaction, the mixture was centrifuged (10000 r / min, 10 min), and the precipitate was washed three times successively with deionized water and anhydrous ethanol. The precipitate was then dried under vacuum at 60°C to obtain vanillic acid / protocatechuic acid composite modified graphene oxide (VA / PCA-GO).

[0040] 2. Preparation of component A of the coating Weigh each raw material according to the following proportions by weight: Deionized water: 18 parts VA / PCA-GO: 5 copies Dispersant (BYK-190): 1 part Defoamer (Foamex 830): 0.3 parts Leveling agent (BYK-333): 0.5 parts Thickener (XS 83): 0.5 parts Titanium dioxide: 15 parts Light calcium carbonate: 10 parts Waterborne epoxy emulsion (E51 type, solid content 50%): 30 parts The preparation process of component A is the same as in Example 1.

[0041] 3. The B component and its dosage are the same as in step 3 of Example 1, to obtain the water-based epoxy anti-corrosion coating.

[0042] Example 3 Waterborne epoxy anticorrosion coating and its preparation 1. Preparation of tannic acid-modified graphene oxide (TA-GO) 50 mg of graphene oxide (GO) was dispersed in 100 mL of Tris-HCl buffer at pH 8.5 and sonicated for 3 hours. Then, 1.0 mM tannic acid (TA) was added, and the mixture was stirred in a 90°C water bath for 6 hours. After the reaction was complete, the mixture was centrifuged, washed (using the same steps as in Example 1), and vacuum dried at 60°C to obtain tannic acid-modified graphene oxide (TA-GO).

[0043] 2. Preparation of component A of the coating Weigh each raw material according to the following proportions by weight: Deionized water: 22 parts TA-GO: 2 servings Dispersant (BYK-190): 1 part Defoamer (Foamex 830): 0.3 parts Leveling agent (BYK-333): 0.5 parts Thickener (XS 83): 0.5 parts Titanium dioxide: 15 parts Light calcium carbonate: 10 parts Waterborne epoxy emulsion (E51 type, solid content 50%): 30 parts The preparation process of component A is the same as in Example 1.

[0044] 3. The B component and its dosage are the same as in step 3 of Example 1, to obtain the water-based epoxy anti-corrosion coating.

[0045] Comparative Example 1: Coatings without added graphene The difference from Example 1 is that GA-GO is not added, and the titanium dioxide content is 18 parts by weight.

[0046] Comparative Example 2: Coatings with added unmodified graphene oxide (GO) The difference from Example 1 is that GA-GO is replaced with unmodified graphene oxide (GO).

[0047] Test Example 1: Coating Performance Test and Results The coatings prepared in Examples 1-3 and Comparative Examples 1 and 2 were sprayed onto sandblasted Q235 carbon steel plates and cured at room temperature for 7 days to obtain a coating with a thickness of approximately 70 μm. The salt spray resistance of the coating was determined according to GB / T 1771-2007; the acid and salt water resistance of the coating was tested according to GB / T 9274-1988; the flexibility of the coating was tested according to GB / T 6742-2007; and the hardness of the coating was tested according to GB / T 6739-2022. The results are shown in Table 1.

[0048] Table 1 Coating performance test results

[0049] As shown in Table 1, the coatings prepared in Examples 1-3 of this invention exhibit significantly better adhesion, impact resistance, and salt spray corrosion resistance than Comparative Example 1 (without graphene) and Comparative Example 2 (unmodified GO). This indicates that biomass phenolic modification can effectively improve the dispersibility and interfacial compatibility of graphene oxide in the coating, thereby synergistically enhancing the overall protective performance of the coating. Among them, Example 3 demonstrates the best performance. The performance of Comparative Example 2 is better than that of Comparative Example 1 but far inferior to that of the embodiments of this invention, proving that the unmodified GO has limited reinforcing effect due to dispersibility and interfacial bonding issues, and may introduce defects due to agglomeration.

[0050] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A coating, characterized in that, The coating is composed of component A and component B, wherein, Component A, by weight, comprises: 30-70 parts of aqueous epoxy emulsion, 0.5-10 parts of biomass phenol-modified graphene oxide, 10-30 parts of pigments and fillers, 0.5-10 parts of additives, and 10-40 parts of water. Component B is a water-based epoxy curing agent, and its dosage is 20% to 40% of the solid weight of the water-based epoxy emulsion in Component A.

2. The coating according to claim 1, characterized in that, The biomass phenols are selected from polyphenolic compounds or phenolic acid compounds, such as one or more of p-hydroxybenzoic acid, gallic acid, vanillic acid, protocatechuic acid, and tannic acid.

3. The coating according to claim 1, characterized in that, The biomass phenol-modified graphene oxide is selected from one or more of gallic acid-modified graphene oxide, vanillic acid and protocatechuic acid composite-modified graphene oxide, and tannic acid-modified graphene oxide.

4. The coating according to claim 1, characterized in that, The solid content of the aqueous epoxy emulsion is 30-70%.

5. The coating according to claim 1, characterized in that, The additives include, but are not limited to, one or more of the following: dispersants, defoamers, leveling agents, and thickeners; Preferably, the additives include 0.5 to 3 parts of dispersant, 0.1 to 1 part of defoamer, 0.2 to 2 parts of leveling agent, and 0.1 to 2 parts of thickener.

6. The coating according to claim 1, characterized in that, The dispersant is selected from polyether-modified styrene-maleic anhydride copolymer polymeric dispersant, the defoamer is selected from polyether-modified fatty acid ester composite defoamer, the leveling agent is selected from nonionic polyether-modified polysiloxane leveling agent, and the thickener is selected from waterborne polyurethane thickener.

7. The coating according to claim 1, characterized in that, The average particle size of the biomass phenol-modified graphene oxide, pigments, fillers, and / or additives does not exceed 50 μm.

8. The method for preparing the coating according to claims 1-7, characterized in that, Includes the following steps: (1) Water, biomass phenol-modified graphene oxide, additives and pigments are dispersed at high speed and then ground to a fineness of ≤ 50μm; (2) After step (1) is completed, add water-based epoxy emulsion and mix to obtain component A; (3) When using, mix component A and component B to obtain the coating; Preferably, the preparation method of the biomass phenol-modified graphene oxide includes: dispersing graphene oxide in a buffer solution with pH 7.5-9.5 and sonicating for 1-5 hours to form a dispersion with a concentration of 1-10 mg / mL; adding biomass phenols and reacting at 60-100℃ for 6-24 hours; after the reaction is completed, centrifuging, washing, and drying are performed to obtain biomass phenol-modified graphene oxide.

9. A coating formed by curing the coating according to any one of claims 1 to 8; Preferably, the coating has any one or more of the following properties: Pencil hardness ≥ 3; Flexibility ≤1mm; Resistance to neutral salt spray ≥420h; Acid resistance time ≥250h; Salt water tolerance time ≥550h; Preferably, the coating is a primer protective layer for steel structures and mechanical equipment.

10. The use of the coating of any one of claims 1 to 8 in the preparation of the coating of claim 9.

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