Environment-friendly water-based phenolic resin anticorrosive coating and preparation process thereof

Abstract

The present application relates to a kind of environment-friendly water-based phenolic resin anticorrosive coating and its preparation process, belong to the field of coating technology.The coating is made of water-based phenolic resin emulsion, hyaluronic acid-lysine composition load nano SiO2-ZnO composite filler, synergistic anticorrosive filler, wetting dispersant, film forming aid, leveling thickener, defoaming agent and deionized water.The superhydrophilic of hyaluronic acid fundamentally solves the dispersion and storage stability problem of phenolic resin in aqueous phase, and the amino group of its lysine side chain can also chemically bond with resin during curing, significantly enhancing the adhesion, flexibility and interfacial bonding strength of coating.At the same time, nano SiO2, ZnO and synergistic anticorrosive filler construct a multiple synergistic anticorrosive network of physical shielding, sacrificial anode and chemical passivation, achieving long-term active protection.The whole system uses water as medium, selects bio-based raw materials and low VOC additives, and the environmental protection is outstanding.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and in particular to an environmentally friendly water-based phenolic resin anticorrosive coating and its preparation process. Background Technology

[0002] With increasingly stringent environmental regulations and a deepening of the concept of sustainable development, the coatings industry is rapidly developing towards water-based, high-solids, and solvent-free technologies. Water-based coatings, using water as the dispersion medium, offer significant advantages such as safety, non-toxicity, non-flammability, and extremely low VOC content, making them a major development direction for environmentally friendly coatings. Phenolic resins hold an irreplaceable position in the field of anti-corrosion coatings due to their excellent bonding strength, heat resistance, chemical resistance (especially acid resistance), and relatively low cost. However, the water-based application of phenolic resins in high-performance anti-corrosion coatings still faces a series of severe technical challenges:

[0003] First, poor water-based compatibility and storage stability are the primary challenges. Phenolic resins are inherently hydrophobic and have extremely poor compatibility with water. Direct dispersion in an aqueous phase easily leads to flocculation, stratification, and sedimentation, resulting in short shelf life, unstable application performance, and difficulty in producing uniform and stable water-based products. Traditional physical blending or simple emulsification methods cannot fundamentally solve this problem.

[0004] Secondly, the overall mechanical properties of the coating are insufficient. After curing, pure phenolic resin has a high cross-linking network density, which leads to the coating being brittle and lacking flexibility. When subjected to impact or substrate deformation, it is prone to micro-cracks or even peeling, which seriously affects its adhesion and long service life as an anti-corrosion coating.

[0005] Furthermore, the anti-corrosion mechanism is singular and lacks long-term effectiveness. Traditional phenolic resin anti-corrosion coatings mainly rely on the chemical resistance of the resin itself as a physical barrier, resulting in passive and limited anti-corrosion function. Adding conventional anti-corrosion fillers (such as zinc powder and zinc phosphate) often leads to problems such as uneven dispersion, weak bonding with the resin interface, and easy "filler-matrix" delamination. Moreover, they are difficult to cope with harsh salt spray, acid-alkali alternation and other complex corrosive environments, and cannot meet the modern industrial demand for long-term and heavy-duty anti-corrosion.

[0006] Furthermore, the agglomeration problem of functional nanofillers also restricts performance improvement. To enhance corrosion resistance, wear resistance, and other properties, it is often necessary to introduce functional fillers such as nano-SiO2 and ZnO. However, these nanoparticles have a large specific surface area and high surface energy, making them extremely prone to agglomeration in aqueous systems. Not only do they fail to exert their nano-effects, but they also become coating defects, accelerating the penetration of corrosive media.

[0007] Therefore, developing an environmentally friendly waterborne coating that can simultaneously solve the problems of stable dispersion, reinforcement and toughening of waterborne phenolic resins, and achieve multifunctional synergistic long-term corrosion protection has become an urgent technical need in this field. Summary of the Invention

[0008] The purpose of this invention is to address the shortcomings of existing technologies by proposing an environmentally friendly water-based phenolic resin anti-corrosion coating and its preparation process.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] This invention provides an environmentally friendly waterborne phenolic resin anticorrosive coating, which, by weight, is composed of the following components: 55-70 parts waterborne phenolic resin emulsion; 15-25 parts hyaluronic acid-lysine composition supported on nano-SiO2-ZnO composite filler; 5-10 parts synergistic anticorrosive filler; 1-2 parts wetting and dispersing agent; 2-4 parts film-forming aid; 0.5-1.5 parts leveling and thickening agent; 0.3-0.8 parts defoamer; and 10-20 parts deionized water.

[0011] Preferably, the aqueous phenolic resin emulsion is PF-EMUL-01 with a solid content of 40-45%, purchased from Shanghai Aoke New Material Technology Co., Ltd.

[0012] Preferably, the synergistic anti-corrosion filler is zinc phosphate or modified polyaniline, wherein the zinc phosphate is ultrafine anti-rust grade zinc phosphate with a particle size of 3-5 μm; and the modified polyaniline is water-based doped polyaniline with a conductivity of 0.5-2.0 S / cm.

[0013] Preferably, the wetting and dispersing agent is BYK-190.

[0014] Preferably, the film-forming aid is a dodecyl alcohol ester.

[0015] Preferably, the leveling thickener is an associative waterborne polyurethane thickener, model QHR 701 or LX-LS-2020.

[0016] Preferably, the defoamer is a mineral oil-based defoamer, specifically DAPRO® AP 7015S or SILCOAF 837.

[0017] Preferably, the preparation method of the hyaluronic acid-lysine composition supporting nano-SiO2-ZnO composite filler is as follows:

[0018] Step 1. Preparation of the hyaluronic acid-lysine composition: Dissolve sodium hyaluronate in 0.1M MES buffer to prepare a 1-2 wt% hyaluronic acid solution. Dissolve lysine in 0.1M MES buffer to prepare a 3-5 wt% lysine solution. In an ice-water bath at 0-4°C and 300-500 rpm, add NHS and EDC sequentially to the HA solution and activate for 15-30 min. Then, slowly add the lysine solution dropwise to the activated hyaluronic acid solution. Adjust the pH of the reaction mixture to 7-8 with 0.1M sodium hydroxide solution. Remove the ice-water bath and heat the reaction system to 20-25°C. Stir continuously for 18-24 h under light-protected conditions. After the reaction is complete, adjust the pH with 0.1M hydrochloric acid solution. The reaction was terminated at 3-4 minutes. The reaction solution was poured into 3-5 times the volume of pre-cooled anhydrous ethanol, allowing the product to precipitate as a flocculent or fibrous precipitate. The crude product was collected by centrifugation at 10000-12000 rpm for 10-15 minutes. The crude product was redissolved in deionized water and dialyzed for 70-75 hours using a dialysis bag with a molecular weight cutoff of 3500-4000 Da, changing the water 3-4 times a day. Finally, the purified solution was freeze-dried for 24-72 hours to obtain the hyaluronic acid-lysine composition (HA-Lys). The reaction equation is as follows:

[0019] .

[0020] Step 2. Directional Loading Composite: Dissolve the hyaluronic acid-lysine composition in deionized water to prepare a 1.0-2.0 wt% solution. Adjust the pH to 8.0-9.0 with 0.1M dilute ammonia. Add nano-SiO2 and nano-ZnO, and stir at 600-800 rpm for 2-4 hours to form a mixed suspension. Transfer the mixed suspension to a high-pressure hydrothermal reactor and heat the reactor to 110-130°C. React for 4-8 hours. After the reaction, cool the reactor to room temperature and centrifuge at 10000-12000 rpm for 10-15 minutes. Discard the supernatant and wash the precipitate 3-5 times with deionized water and ethanol by alternating centrifugation. Place the washed precipitate in a vacuum drying oven and dry at 60-80°C for 20-24 hours to obtain the hyaluronic acid-lysine composition loaded with nano-SiO2-ZnO.

[0021] Preferably, the sodium hyaluronate has a molecular weight of 50-200 kDa, and the mass ratio of sodium hyaluronate to lysine is 1:0.5-2; the molar ratio of EDC to lysine is 2-3:1, and the molar ratio of EDC to NHS is 1:0.5-1.

[0022] Preferably, the mass ratio of the hyaluronic acid-lysine composition, SiO2, and ZnO is 1:2-3:2, and the particle size of the nano-SiO2 and ZnO is 10-30 nm.

[0023] The preparation of the hyaluronic acid-lysine composition (HA-Lys) involves an EDC / NHS-mediated amidation coupling reaction. In this process, sodium hyaluronate dissolves in MES buffer, and the sodium carboxylate group (-COONa) on its side chain is partially protonated to form a reactive carboxyl group (-COOH). Under low-temperature ice bath conditions, the carboxyl group (-COOH) on the side chain is first activated by EDC and forms a stable active ester intermediate with NHS. Subsequently, the ε-amino group on the lysine side chain, which has stronger nucleophilicity, attacks the active ester under weakly alkaline conditions (pH 7-8) to form a covalent amide bond, thereby grafting lysine onto the hyaluronic acid chain as a side chain. After the reaction, the product is precipitated by adjusting the pH to an acidic environment, and then purified by dialysis and freeze-dried to finally obtain the HA-Lys complex rich in free primary amino groups (-NH2). These amino groups are the key sites for subsequent reactions with the resin matrix.

[0024] This composite further achieves directional loading and composite with nano-SiO2 and ZnO through hydrothermal assisted self-assembly. Under alkaline conditions (pH 8.0-9.0), the HA-Lys chains are fully extended and negatively charged, and their carboxyl and amino groups can interact with Zn through electrostatic interactions, hydrogen bonds, and coordination bonds. 2+ The initial adsorption onto the surface of nanoparticles is followed by a hydrothermal reaction (110-130°C), which is a key step. This process provides a high-temperature and high-pressure environment, which greatly promotes the rearrangement, tight adsorption, and enhanced interfacial interaction of HA-Lys molecular chains on the surface of inorganic particles. This may lead to a more stable chemical bond, thereby constructing an organic-inorganic hybrid core-shell structure with SiO2 / ZnO as the "core" and HA-Lys as the strong "shell". After centrifugation, washing, and drying, a composite filler with good dispersibility, strong interfacial bonding, and multiple reactivity and functions is obtained.

[0025] This invention provides a preparation process for the above-mentioned environmentally friendly water-based phenolic resin anticorrosive coating, comprising the following steps:

[0026] S1. Pre-made base material slurry: Take hyaluronic acid-lysine composition loaded with nano-SiO2-ZnO composite filler, wetting and dispersing agent, 50-60% of defoamer and 50-60% of deionized water, mix them, transfer them into a high-speed disperser, and disperse them at a speed of 2000-3000 r / min for 30-45 min to obtain a uniform base material slurry without particle agglomeration;

[0027] S2. Low-speed mixing to form paint: While maintaining low-speed stirring, add water-based phenolic resin emulsion, synergistic anti-corrosion filler, film-forming aid, leveling thickener and 40-50% of defoamer to the above base slurry in sequence, and stir at low speed of 500-800r / min for 20-30min.

[0028] S3. Viscosity Adjustment and Fine Filtration: Add 40-50% deionized water to adjust the viscosity of the coating system, stir at low speed of 300-500 rpm for 40-60 seconds, let stand to defoam for 30-60 minutes, filter through a 200-mesh filter to remove impurities, and obtain an environmentally friendly water-based phenolic resin anti-corrosion coating.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] 1. This invention fundamentally solves the compatibility and stability problems of waterborne phenolic resins: Traditional phenolic resins have poor hydrophilicity and are difficult to disperse stably in aqueous systems, which easily leads to stratification and sedimentation during coating storage. This invention introduces a hyaluronic acid-lysine composition as a modified bridge and coating material. Hyaluronic acid has extremely strong hydrophilicity and hydration ability, which enables the nanofillers and resin systems it supports to obtain superhydrophilic properties, thereby achieving ultra-uniform and ultra-stable dispersion of phenolic resins in the aqueous phase, and revolutionizing the storage stability of coatings.

[0031] 2. Significantly enhanced mechanical properties and interfacial bonding of the coating: Traditional phenolic resin coatings are brittle and have limited adhesion to the substrate. In this invention, nano-SiO2 loaded with a hyaluronic acid-lysine composition serves as reinforcing particles, effectively improving the coating's hardness and toughness. More importantly, the primary amino groups (-NH2) abundant in the lysine side chain can chemically react with the active groups (such as hydroxymethyl) of the phenolic resin during the coating curing process, forming covalent bonds. This "chemically welds" the inorganic filler into the organic resin network, greatly strengthening the interfacial bonding. As a result, the coating achieves excellent adhesion, flexibility, and impact resistance, overcoming the brittleness of pure phenolic resin.

[0032] 3. A multi-layered, long-lasting, active-passive integrated anti-corrosion system was constructed: This invention is not a simple physical mixture of fillers, but rather a synergistic protective network constructed through an "organic-inorganic hybrid" design. Nano-SiO2 and a dense resin-filler composite network form a super-strong physical barrier layer, nano-ZnO provides sacrificial anode protection, and synergistic fillers (zinc phosphate or polyaniline) can passivate the metal substrate. The three work together to achieve all-round anti-corrosion from physical shielding to active electrochemical protection. This composite structure enhances the overall resistance of the coating to acid, alkali, and salt spray erosion, achieving a long-lasting anti-corrosion effect that surpasses the superposition of single mechanisms.

[0033] 4. Achieved high environmental friendliness across the entire system: The entire formulation uses water as the dispersion medium, the selected resin emulsion has a low free phenol content, and the core modifiers sodium hyaluronate and lysine are bio-based raw materials. Combined with environmentally friendly additives, this ensures that the coating has extremely low VOC content, fully meeting the stringent requirements of green chemistry and sustainable development. Detailed Implementation

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with existing known technologies. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0035] Preparation Example 1: The preparation method of hyaluronic acid-lysine composition supported on nano-SiO2-ZnO composite filler is as follows:

[0036] Step 1. Preparation of hyaluronic acid-lysine composition: Take 5.0 g of sodium hyaluronate with a molecular weight of 100 kDa, dissolve it in 325 mL of 0.1 M MES buffer, take 5.0 g of lysine, dissolve it in 120 mL of 0.1 M MES buffer, and stir in an ice-water bath at 400 rpm. Add 7.87 g of NHS and 16.39 g of EDC to the hyaluronic acid solution in sequence. After activation for 20 min, add lysine solution dropwise, adjust the pH to 7.5 with 0.1 M NaOH, react at 25 °C in the dark for 20 h, adjust the pH to 3.5 with 0.1 M HCl, pour in 2 L of pre-cooled ethanol to precipitate, centrifuge at 10000 rpm for 15 min, collect the crude product, redissolve the crude product in deionized water, dialyze using a dialysis bag with a molecular weight cutoff of 3500 Da for 72 h, change the water 3 times a day, and finally freeze-dry the purified solution for 72 h to obtain the hyaluronic acid-lysine composition.

[0037] Step 2. Directional Loading Composite: Take 4g of the hyaluronic acid-lysine composition, dissolve it in 260mL of deionized water, adjust the pH to 8.5 with 0.1M ammonia water, add 10g of 20nm nano-SiO2 and 8g of 20nm nano-ZnO, stir at 700rpm for 3h to form a mixed suspension, transfer the suspension to a hydrothermal reactor, react at 120℃ for 6h, after the reaction is completed, cool the reactor to room temperature, centrifuge at 10000rpm for 15min, discard the supernatant, wash the precipitate 4 times with deionized water and ethanol by alternating centrifugation, place the washed precipitate in a vacuum drying oven, dry at 60°C for 24h to obtain the hyaluronic acid-lysine composition loaded with nano-SiO2-ZnO.

[0038] Preparation Example 2: The preparation method of hyaluronic acid-lysine composition supported on nano-SiO2-ZnO composite filler is as follows:

[0039] Step 1. Preparation of hyaluronic acid-lysine composition: Take 5.0 g of hyaluronic acid with a molecular weight of 100 kDa, dissolve it in 245 mL of 0.1 M MES buffer, take 10.0 g of lysine, dissolve it in 190 mL of 0.1 M MES buffer, and in an ice-water bath, stir at 400 rpm. Add 23.61 g of NHS and 39.33 g of EDC to the hyaluronic acid solution in sequence. After activation for 30 min, add lysine solution dropwise, adjust the pH to 7.5 with 0.1 M NaOH, react at 25 °C in the dark for 24 h, adjust the pH to 3.5 with 0.1 M HCl, pour in 2 L of pre-cooled ethanol to precipitate, centrifuge at 10000 rpm for 15 min, collect the crude product, redissolve the crude product in deionized water, dialyze using a dialysis bag with a molecular weight cutoff of 3500 Da for 75 h, change the water 3 times a day, and finally freeze-dry the purified solution for 72 h to obtain the hyaluronic acid-lysine composition.

[0040] Step 2. Targeted Loading and Composite: Dissolve 4g of the hyaluronic acid-lysine composition in 200mL of deionized water, adjust the pH to 8.5 with 0.1M ammonia, and add 12g of nanoparticles with a particle size of 20nm. 8g of 20nm nano-ZnO was stirred at 700rpm for 4h to form a mixed suspension. The suspension was transferred to a hydrothermal reactor and reacted at 120℃ for 8h. After the reaction was completed, the reactor was cooled to room temperature and centrifuged at 10000rpm for 15min. The supernatant was discarded, and the precipitate was washed 5 times with deionized water and ethanol by alternating centrifugation. The washed precipitate was placed in a vacuum drying oven and dried at 60°C for 24h to obtain hyaluronic acid-lysine composition supported on nano-SiO2-ZnO.

[0041] Preparation Example 3: The preparation method of hyaluronic acid-lysine composition supported on nano-SiO2-ZnO composite filler is as follows:

[0042] Step 1. Preparation of hyaluronic acid-lysine composition: Take 5.0 g of hyaluronic acid with a molecular weight of 100 kDa and dissolve it in 495 mL of 0.1 M MES buffer. Take 2.5 g of lysine and dissolve it in 80 mL of 0.1 M MES buffer. In an ice-water bath, with stirring at 400 rpm, add 7.87 g of NHS and 6.56 g of EDC to the hyaluronic acid solution in sequence. After activation for 20 min, add lysine solution dropwise. Adjust the pH to 7.5 with 0.1 M NaOH and react at 25 °C in the dark for 20 h. Adjust the pH to 3.5 with 0.1 M HCl. Pour in 2 L of pre-cooled ethanol to precipitate. Centrifuge at 10000 rpm for 15 min and collect the crude product. Redissolve the crude product in deionized water and dialyze for 72 h using a dialysis bag with a molecular weight cutoff of 3500 Da. Change the water 3 times a day. Finally, freeze-dry the purified solution for 72 h to obtain the hyaluronic acid-lysine composition.

[0043] Step 2. Directional Loading Composite: Take 4g of the hyaluronic acid-lysine composition, dissolve it in 396mL of deionized water, adjust the pH to 8.5 with 0.1M ammonia water, add 8g of 20nm nano-SiO2 and 8g of 20nm nano-ZnO, stir at 700rpm for 2h to form a mixed suspension, transfer the suspension to a hydrothermal reactor, react at 120℃ for 4h, after the reaction is completed, cool the reactor to room temperature, centrifuge at 10000rpm for 15min, discard the supernatant, wash the precipitate 3 times with deionized water and ethanol by alternating centrifugation, place the washed precipitate in a vacuum drying oven, dry at 60°C for 24h to obtain the hyaluronic acid-lysine composition loaded with nano-SiO2-ZnO.

[0044] Example 1: A preparation process for an environmentally friendly water-based phenolic resin anticorrosive coating, comprising the following steps:

[0045] S1. Pre-made base material slurry: Take 20 parts of the hyaluronic acid-lysine composition prepared in Preparation Example 1, load nano-SiO2-ZnO composite filler, 1.5 parts of wetting and dispersing agent (BYK-190), 0.275 parts of defoamer (DAPRO® AP7015S), and 7.5 parts of deionized water, mix them, transfer them to a high-speed disperser, and disperse them at a high speed of 2500 r / min for 35 min to obtain a uniform base material slurry without particle agglomeration;

[0046] S2. Low-speed mixing to form paint: Add 62.5 parts of water-based phenolic resin emulsion (PF-EMUL-01, solid content 42%), 7.5 parts of synergistic anti-corrosion filler (ultra-fine anti-rust grade zinc phosphate, particle size 4μm), 3 parts of film-forming aid (alcohol ester dodecyl), 1.0 part of leveling thickener (QHR 701) and 0.275 parts of defoamer (DAPRO® AP 7015S) to the above base slurry in sequence, and stir at a low speed of 600r / min for 25min;

[0047] S3. Viscosity Adjustment and Fine Filtration: Add 7.5 parts of deionized water to adjust the viscosity of the coating system, stir at low speed of 400 rpm for 50 seconds, let stand to defoam for 45 minutes, filter through a 200-mesh filter to remove impurities, and obtain an environmentally friendly water-based phenolic resin anti-corrosion coating.

[0048] Example 2: A preparation process for an environmentally friendly water-based phenolic resin anticorrosive coating, comprising the following steps:

[0049] S1. Pre-made base material slurry: Take 25 parts of the hyaluronic acid-lysine composition prepared in Preparation Example 2, load nano-SiO2-ZnO composite filler, 2 parts of wetting and dispersing agent (BYK-190), 0.48 parts of defoamer (SILCO AF 837) and 12 parts of deionized water, mix them, transfer them into a high-speed disperser, and disperse them at a high speed of 3000 r / min for 45 min to obtain a uniform base material slurry without particle agglomeration;

[0050] S2. Low-speed mixing to form paint: Add 70 parts of waterborne phenolic resin emulsion (PF-EMUL-01, solid content 42%), 10 parts of synergistic anti-corrosion filler (waterborne doped polyaniline, conductivity 2.0 S / cm), 4 parts of film-forming aid (alcohol ester dodecyl), 1.5 parts of leveling thickener (LX-LS-2020) and 0.32 parts of defoamer (SILCO AF 837) to the above base slurry in sequence, and stir at a low speed of 800 r / min for 30 min;

[0051] S3. Viscosity Adjustment and Fine Filtration: Add 8 parts of deionized water to adjust the viscosity of the coating system, stir at low speed of 500 rpm for 60 seconds, let stand to defoam for 60 minutes, filter through a 200-mesh filter to remove impurities, and obtain an environmentally friendly water-based phenolic resin anti-corrosion coating.

[0052] Example 3: A preparation process for an environmentally friendly water-based phenolic resin anticorrosive coating, comprising the following steps:

[0053] S1. Pre-made base material slurry: Take 15 parts of the hyaluronic acid-lysine composition prepared in Preparation Example 3, load nano-SiO2-ZnO composite filler, 1 part of wetting and dispersing agent (BYK-190), 0.15 parts of defoamer (Haimingsi DAPRO® AP7015S) and 5 parts of deionized water, mix them, transfer them to a high-speed disperser, and disperse them at a high speed of 2000 r / min for 30 min to obtain a uniform base material slurry without particle agglomeration;

[0054] S2. Low-speed mixing to form paint: Add 55 parts of water-based phenolic resin emulsion (PF-EMUL-01, solid content 42%), 5 parts of synergistic anti-corrosion filler (ultra-fine anti-rust grade zinc phosphate, particle size 4μm), 2 parts of film-forming aid (alcohol ester dodecyl), 0.5 parts of leveling thickener (QHR 701) and 0.15 parts of defoamer (DAPRO® AP 7015S) to the above base slurry in sequence, and stir at a low speed of 500r / min for 20min;

[0055] S3. Viscosity Adjustment and Fine Filtration: Add 5 parts of deionized water to adjust the viscosity of the coating system, stir at low speed of 300 rpm for 40 seconds, let stand to defoam for 30 minutes, filter through a 200-mesh filter to remove impurities, and obtain an environmentally friendly water-based phenolic resin anti-corrosion coating.

[0056] Comparative Example 1: Based on Example 1, the difference is that the hyaluronic acid-lysine composition supporting nano-SiO2-ZnO composite filler is not added, otherwise it is the same as Example 1.

[0057] Comparative Example 2: Based on Example 1, the difference is that 3.33g of the hyaluronic acid-lysine composition obtained in Preparation Example 1, 10g of nano SiO2, and 6.67g of nano ZnO were simply physically ground and mixed in a mortar for 5 minutes, and the rest was the same as in Example 1.

[0058] Comparative Example 3: Based on Example 1, the difference is that the hyaluronic acid-lysine composition was not used, and 12g of nano-SiO2 and 8g of nano-ZnO were directly mixed. The rest was the same as in Example 1.

[0059] Comparative Example 4: Based on Example 1, the difference is that only 20 parts of the hyaluronic acid-lysine composition were added, and the rest was the same as in Example 1.

[0060] Comparative Example 5: Based on Example 1, the difference is that the hyaluronic acid-lysine composition loaded with nano-SiO2-ZnO composite filler was replaced with an equal amount of single nano-SiO2, and the rest was the same as in Example 1.

[0061] Comparative Example 6: Based on Example 1, the difference is that the hyaluronic acid-lysine composition-supported nano-SiO2-ZnO composite filler was replaced with an equal amount of single nano-ZnO, and the rest was the same as in Example 1.

[0062] Comparative Example 7: Based on Example 1, the difference is that no synergistic anti-corrosion filler is added, otherwise it is the same as Example 1.

[0063] Comparative Example 8: Based on Example 1, the difference is that ultrafine zinc phosphate (3-5 μm) was replaced with an equal amount of ordinary zinc phosphate (particle size >10 μm), and the rest is the same as in Example 1.

[0064] The environmentally friendly waterborne phenolic resin anti-corrosion coatings obtained in Examples 1-3 and Comparative Examples 1-8 were used to prepare coatings on sandblasted Q235 steel plates (150mm×70mm×1mm). After surface drying at room temperature for 10-30 minutes, the coatings were transferred to an oven for curing. The temperature was increased from room temperature to 80-90°C at a rate of 2-5°C / min and held at this temperature for 20-40 minutes. Then, the temperature was increased to 120-140°C and held at this final temperature for 40-60 minutes. The coatings were then allowed to cool naturally to room temperature to obtain the anti-corrosion coating. The dry film thickness was controlled at 80±5μm. The coated test plates were cured in a standard environment of (23±2)°C and (50±5)% relative humidity for at least 16 hours before testing.

[0065] Performance testing:

[0066] 1. Adhesion: Referring to GB / T 9286-2021 standard, use a 1mm pitch multi-blade cutter to cut a cross grid of horizontal and vertical lines on the paint film surface, with the cutting depth penetrating the paint film to the substrate; after applying standard pressure-sensitive tape, peel it off vertically and quickly, and evaluate it according to the standard chart from 0 to 5, with 0 being the best and the higher the grade, the worse the adhesion.

[0067] 2. Flexibility: Referring to GB / T 1731-2020 standard, the shaft bending method is adopted. The test plate is bent at a constant speed of 180° around the shaft of the corresponding diameter with the paint film facing upward. The minimum shaft diameter (mm) without paint film cracking or peeling is recorded. The smaller the value, the better the flexibility.

[0068] 3. Impact resistance: Referring to GB / T 1732-2020, the frontal impact method is adopted. A 1kg hammer is dropped freely, and the maximum impact height (cm) without cracking, peeling, or wrinkling of the paint film is recorded. The higher the value, the better the impact resistance.

[0069] 4. Resistance to neutral salt spray (5% NaCl): Refer to GB / T 1771-2007 standard, spray continuously at 35±2℃, and record the time (h) when the paint film first appears to blister, rust, and peel off. At the same time, record the degree of paint film damage within 1000h. The longer the time, the better the salt spray resistance.

[0070] 5. Acid resistance ( (Refer to GB / T 9274-1988 standard, soak at room temperature for 168 hours, and observe the condition of the paint film after removal. The rating is as follows: no abnormality, slight blistering / loss of gloss, obvious blistering / rust, large area peeling / substrate corrosion.)

[0071] 6. Alkali resistance (10% NaOH): Refer to GB / T 9274-1988 standard, immerse at room temperature for 168 hours, remove and observe the paint film condition, and evaluate the grade in the same way as the acid resistance test.

[0072] 7. Storage stability (50℃, 30 days): According to GB / T 6753.3-1986 standard, after sealing the sample, place it in an oven at 50±2℃ and let it stand for 30 days. After cooling to room temperature, evaluate the sedimentation (no sedimentation, slight sedimentation that can be dispersed by stirring, severe sedimentation and agglomeration) and viscosity change rate (≤5% is excellent, 5%-10% is qualified, and >10% is unqualified).

[0073] Table 1. Test results of physical and mechanical properties and storage stability of the coating

[0074]

[0075] Table 2. Test results of coating corrosion resistance

[0076]

[0077] Data Analysis:

[0078] 1. Analysis of the physical and mechanical properties of the coating

[0079] Adhesion: Examples 1-3 all achieved a grade of 0 (optimal), while Comparative Examples 1-8 generally ranged from 1 to 3. This indicates that the chemical bonding between the amino groups of lysine in the hyaluronic acid-lysine (HA-Lys) composition and the phenolic resin "welds" the filler to the resin network, achieving the strongest interfacial bonding. Comparative Examples 1 (without composite filler) and 3 (without HA-Lys) exhibited the worst adhesion (grades 2-3), directly demonstrating the lack of chemical bridging effect of HA-Lys and resulting in weak interfacial bonding.

[0080] Flexibility and Impact Resistance: Examples 1-3 exhibited the best flexibility (Φ2mm) and impact resistance (≥50cm). Comparative Examples 1 (without composite filler) and 3 (without HA-Lys) again showed the worst performance, demonstrating that the composite of HA-Lys and nano-SiO2 plays a crucial role in toughening and strengthening, effectively overcoming the brittleness of phenolic resin. Comparative Example 2 (physical mixing) showed performance in between, indicating that the robust core-shell structure formed by the hydrothermal method contributes more to stress transfer and energy dissipation than simple physical mixing.

[0081] 2. Storage stability analysis

[0082] Examples 1-3 showed no sedimentation after 30 days of accelerated storage at 50°C, with a viscosity change rate of <5%, demonstrating excellent stability. This is entirely due to the strong hydrophilicity and steric hindrance effect of hyaluronic acid. Comparative Examples 1, 3, 4, and 2, 5, 6 all exhibited varying degrees of sedimentation or significant increases in viscosity, indicating that whether it is the lack of dispersion and stabilization by HA-Lys or the failure to form an effective coating through physical mixing alone, both lead to a decrease in system stability.

[0083] 3. Analysis of long-term corrosion resistance

[0084] Resistance to neutral salt spray: Examples 1-3 showed significantly superior performance, all exceeding 1000 hours without defects. In contrast, the best of Comparative Examples 1-8 (Comparative Example 7) only lasted 600 hours, and the worst (Comparative Example 1) only 120 hours. This strongly demonstrates the effectiveness of the multi-layered synergistic anti-corrosion network constructed in this invention: nano-SiO2 and the dense resin network form a physical barrier; nano-ZnO provides sacrificial anode protection; and zinc phosphate / polyaniline further passivates the metal substrate. These three elements work closely together through an organic-inorganic hybrid structure, achieving an anti-corrosion effect of "1+1+1>3". Comparative Example 1 (without composite filler): Relying solely on the resin body, it exhibits poor barrier properties and the lowest anti-corrosion performance. Comparative Example 3 (without HA-Lys) and Comparative Example 2 (physical mixture): Nanoparticles exhibit severe agglomeration or weak interfacial bonding, forming defective channels that allow easy penetration of corrosive media, resulting in performance far inferior to Examples 1-3. Comparative Example 4 (HA-Lys only): Lacking the active corrosion protection function of nano-SiO2 / ZnO, relying solely on the organic barrier, its salt spray resistance (450h) is limited. Comparative Examples 5 and 6 (single nanofiller): Using only SiO2 or ZnO respectively, the performance (350h, 380h) indicates that the two are complementary and synergistic in their corrosion protection mechanisms; the absence of either leads to performance limitations. Comparative Examples 7 and 8: Lacking synergistic fillers or using coarse-grained fillers, the performance (600h, 550h) is acceptable but not optimal, demonstrating that the auxiliary passivation effect of zinc phosphate / polyaniline and the fineness of the filler significantly contribute to improving the corrosion resistance limit.

[0085] Acid and alkali resistance: The coating films in Examples 1-3 remained intact after 168 hours of immersion, demonstrating excellent resistance to chemical media. This is not only an inherent characteristic of phenolic resin, but also due to the dense composite filler network significantly delaying media penetration. Comparative Examples 1, 2, and 3 all exhibited significant blistering and peeling in acidic and alkaline media, indirectly confirming the integrity advantage of the composite coating structure of this invention under harsh chemical environments.

[0086] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An environmentally friendly water-based phenolic resin anticorrosive coating, characterized in that, It is composed of the following components by weight: 55-70 parts of waterborne phenolic resin emulsion; 15-25 parts of hyaluronic acid-lysine composition supported on nano-SiO2-ZnO composite filler; 5-10 parts of synergistic anti-corrosion filler; 1-2 parts of wetting and dispersing agent; 2-4 parts of film-forming aid; 0.5-1.5 parts of leveling and thickening agent; 0.3-0.8 parts of defoamer; 10-20 parts of deionized water; wherein, the hyaluronic acid-lysine composition supported on nano-SiO2-ZnO composite filler is a composite filler in which sodium hyaluronate and lysine are directionally grafted through low-temperature activation via EDC / NHS, and then used as an organic carrier to hydrothermally support nano-SiO2 and nano-ZnO.

2. The environmentally friendly water-based phenolic resin anticorrosive coating according to claim 1, characterized in that, The aqueous phenolic resin emulsion is model PF-EMUL-01 with a solid content of 40-45%.

3. The environmentally friendly water-based phenolic resin anticorrosive coating according to claim 1, characterized in that, The synergistic anti-corrosion filler is zinc phosphate or modified polyaniline, wherein the zinc phosphate is ultrafine anti-rust grade zinc phosphate with a particle size of 3-5 μm; and the modified polyaniline is water-based doped polyaniline with a conductivity of 0.5-2.0 S / cm.

4. The environmentally friendly water-based phenolic resin anticorrosive coating according to claim 1, characterized in that, The wetting and dispersing agent is BYK-190; the film-forming aid is 12-ol ester; the leveling and thickening agent is an associative waterborne polyurethane thickener, model QHR 701 or LX-LS-2020; the defoamer is a mineral oil-based defoamer, model DAPRO®AP 7015S or SILCO AF 837.

5. The environmentally friendly water-based phenolic resin anticorrosive coating according to claim 1, characterized in that, The hyaluronic acid-lysine composition supported on nano-SiO2-ZnO composite filler is prepared by a method comprising the following steps: Step 1. Preparation of hyaluronic acid-lysine composition: Dissolve sodium hyaluronate in 0.1M MES buffer to prepare a 1-2 wt% solution, and dissolve lysine in 0.1M MES buffer to prepare a 3-5 wt% solution. In an ice-water bath at 0-4°C and 300-500 rpm, add NHS and EDC sequentially to the hyaluronic acid solution and activate at low temperature for 15-30 min. Then, slowly add the lysine solution dropwise to the activated hyaluronic acid solution. After the addition is complete, adjust the pH of the system to 7-8 with dilute alkali solution, remove the ice-water bath, and react at 20-25°C in the dark for 18-24 h. After the reaction is complete, adjust the pH of the system to 3-4 with dilute acid, slowly pour the reaction solution into pre-cooled anhydrous ethanol for full precipitation, collect the crude product by centrifugation, remove impurities by dialysis, and freeze-dry to obtain the hyaluronic acid-lysine composition. Step 2. Directional Loading Composite: Dissolve the hyaluronic acid-lysine composition in deionized water to prepare a 1.0-2.0 wt% solution. Adjust the pH of the system to 8.0-9.0 with dilute ammonia. Add nano-SiO2 and nano-ZnO, and stir continuously for 2-4 hours to form a mixed suspension. Transfer the mixed suspension to a hydrothermal reactor and hydrothermally react at a constant temperature of 110-130℃ for 4-8 hours. After the reaction is completed, centrifuge to separate the solid product, wash with deionized water until neutral, and dry to obtain the hyaluronic acid-lysine composition-loaded nano-SiO2-ZnO composite filler.

6. The environmentally friendly water-based phenolic resin anticorrosive coating according to claim 5, characterized in that, In step 1, the molecular weight of sodium hyaluronate is 50-200 kDa, and the mass ratio of sodium hyaluronate to lysine is 1:0.5-2; the molar ratio of EDC to lysine is 2-3:1, and the molar ratio of EDC to NHS is 1:0.5-1.

7. The environmentally friendly water-based phenolic resin anticorrosive coating according to claim 5, characterized in that, In step 2, the mass ratio of the hyaluronic acid-lysine composition, nano-SiO2, and nano-ZnO is 1:2-3:2, and the particle size of nano-SiO2 and nano-ZnO is 10-30 nm.

8. A preparation process for an environmentally friendly waterborne phenolic resin anticorrosive coating as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Pre-made base material slurry: Take hyaluronic acid-lysine composition loaded with nano-SiO2-ZnO composite filler, wetting and dispersing agent, 50-60% of defoamer and 50-60% of deionized water, mix them, transfer them into a high-speed disperser, and disperse them at a speed of 2000-3000 r / min for 30-45 min to obtain a uniform base material slurry without particle agglomeration; S2. Low-speed mixing to form paint: While maintaining low-speed stirring, add water-based phenolic resin emulsion, synergistic anti-corrosion filler, film-forming aid, leveling thickener and 40-50% of defoamer to the above base slurry in sequence, and stir at low speed of 500-800r / min for 20-30min. S3. Viscosity Adjustment and Fine Filtration: Add 40-50% deionized water to adjust the viscosity of the coating system, stir at low speed of 300-500 rpm for 40-60 seconds, let stand to defoam for 30-60 minutes, filter through a 200-mesh filter to remove impurities, and obtain an environmentally friendly water-based phenolic resin anti-corrosion coating.

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