Hyperbranched epoxy resin anticorrosive paint and preparation method thereof
By introducing hydroxyl-terminated hyperbranched polyester and flake fillers into epoxy resin coatings, a coating with high flexibility and multi-layered shielding structure is constructed, solving the problems of high brittleness and poor impact resistance of traditional epoxy resin coatings, and achieving high-performance anti-corrosion effect and construction applicability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- LONGYUAN SHAANXI WIND POWER GENERATION CO LTD
- Filing Date
- 2025-12-22
- Publication Date
- 2026-05-01
AI Technical Summary
Traditional epoxy resin coatings are brittle, have poor impact resistance and peel resistance due to their high crosslinking density and poor molecular chain mobility. They are prone to microcracks when equipment vibrates or the substrate is deformed, which leads to corrosion failure.
Hydroxyl-terminated hyperbranched polyester was used as a modifier, combined with sheet fillers and specific additives, to construct a coating with high flexibility and multi-layer shielding structure. Through the synergistic effect of the three-dimensional spherical structure of the hydroxyl-terminated hyperbranched polyester and the sheet fillers, a dense, interpenetrating network was formed, which enhanced the toughness and anti-corrosion performance of the coating. Polyamide curing agent and silane coupling agent were used to improve adhesion and flexibility.
It significantly improves the toughness, impact resistance and peel resistance of the coating, extends the anti-corrosion performance, ensures the long-term reliability of the coating in harsh environments, and maintains good application performance and adhesion.
Smart Images
Figure CN121950141A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of anti-corrosion coatings, and more particularly to a hyperbranched epoxy resin anti-corrosion coating and its preparation method. Background Technology
[0002] Epoxy resin coatings have become one of the most widely used coating types in heavy-duty anti-corrosion fields (such as marine engineering, petrochemicals, bridges, and ships) due to their excellent adhesion, outstanding chemical stability, high mechanical strength, and good corrosion resistance. Their anti-corrosion mechanism mainly relies on forming a strong chemical bond with the metal substrate to provide excellent adhesion. Simultaneously, after curing, they form a highly cross-linked, dense three-dimensional network structure, effectively blocking the penetration of water, oxygen, and corrosive ions.
[0003] Traditional epoxy resins have high crosslinking density and poor molecular chain mobility after curing, resulting in high brittleness, poor impact resistance and peel resistance. They are prone to microcracks when subjected to equipment vibration, thermal cycling or substrate deformation, leading to corrosion failure. Summary of the Invention
[0004] The present invention aims to provide a hyperbranched epoxy resin anti-corrosion coating and its preparation method to solve the problems mentioned in the background art.
[0005] To achieve the above objectives, the present invention provides the following technical solution: A hyperbranched epoxy resin anti-corrosion coating is a two-component system, comprising component A and component B: Component A, by weight, includes the following components: Epoxy resin matrix: 40-70 parts; Hyperbranched polymer modifier: 5-20 parts; the hyperbranched polymer modifier is a hydroxyl-terminated hyperbranched polyester with a generation number of G2 to G4 and a hydroxyl functionality of 8-32; the hydroxyl-terminated hyperbranched polyester is prepared by melt polycondensation reaction of trimethylolpropane as the core and 2,2-dimethylolpropionic acid. Flake packing: 10-30 parts; Rust-preventive pigment: 5-15 parts; Reactive diluent: 0-10 parts; Additives: 1-5 parts; Component B is a curing agent, specifically a polyamide curing agent; wherein, components A and B are configured to be mixed in a weight ratio of 4:1 to 5:1.
[0006] Preferably, the epoxy resin matrix is bisphenol A type epoxy resin.
[0007] Preferably, the sheet-like filler is selected from at least one of mica iron oxide, glass flakes, or ferrophosphorus powder.
[0008] Preferably, the anti-rust pigment is zinc phosphate.
[0009] Preferably, the additives include dispersants, defoamers, and leveling agents.
[0010] A method for preparing a hyperbranched epoxy resin anticorrosive coating, used in any one of claims 1 to 5, comprising the following steps: (1) Preparation of component A: a. Premixing: The epoxy resin matrix and the hyperbranched polymer modifier are stirred and mixed at 60-75°C for 30-60 minutes to obtain the modified epoxy resin base material; b. Grinding and dispersing: The modified epoxy resin base material obtained in step a is pre-dispersed with all the flake fillers, anti-rust pigments and dispersants, and then ground to a fineness of ≤50μm to obtain a slurry; c. Paint mixing: Add the defoamer, leveling agent and reactive diluent to the slurry obtained in step b, stir evenly and filter to obtain component A; (2) Preparation of component B: The polyamide curing agent and coupling agent are mixed evenly to obtain component B.
[0011] Preferably, in step a, the preparation method of the hyperbranched polymer modifier is as follows: under nitrogen protection and in the presence of an esterification catalyst, trimethylolpropane and excess 2,2-dimethylolpropionic acid are subjected to a melt polycondensation reaction at 135-150°C, and the reaction endpoint is controlled by monitoring the acid value of the system to obtain a terminal hydroxyl hyperbranched polyester of the target generation, wherein the esterification catalyst is p-toluenesulfonic acid.
[0012] Preferably, in step b, the grinding is performed using a three-roll mill.
[0013] Preferably, in step c, the active diluent is selected from at least one of benzyl glycidyl ether, butyl glycidyl ether, or polyethylene glycol diglycidyl ether.
[0014] Preferably, in step (2), the coupling agent is a silane coupling agent, and the amount added is 0.5-2.0% of the weight of the polyamide curing agent.
[0015] The beneficial effects of this technical solution compared to existing technologies are as follows: (1) This solution uses hydroxyl-terminated hyperbranched polyester (HBP-OH) as an internal toughening modifier. Its highly branched three-dimensional spherical structure acts as an "elastic micro-region" in the epoxy curing network, which can effectively induce creasing, terminate crack propagation, and absorb impact energy. Without sacrificing the coating hardness and crosslinking density, it significantly improves the coating's toughness, impact resistance, and peel resistance. This fundamentally overcomes the defects of traditional epoxy resins, which are brittle and prone to microcracks due to high crosslinking density and poor chain segment mobility. It allows the coating to remain intact when subjected to equipment vibration, thermal cycling, or substrate deformation, avoiding corrosion media penetration and anti-corrosion failure caused by microcracks. At the same time, by setting hydroxyl-terminated hyperbranched polyesters with specific generations (G2-G4) and functionalities (8-32), it achieves the best balance between molecular size, solubility, and reactivity. Lower-generation hydroxyl-terminated hyperbranched polyesters can more effectively reduce system viscosity, while the abundant hydroxyl groups can deeply participate in curing and crosslinking, forming a denser and more uniform "rigid-tough interpenetrating network". This molecular design not only ensures excellent toughening effect, but also enhances the cohesive strength and integrity of the coating.
[0016] (2) By setting up a synergistic system of terminal hydroxyl hyperbranched polyester and sheet filler, the excellent dispersibility and wettability of terminal hydroxyl hyperbranched polyester are utilized to promote the parallel orientation of sheet filler in the resin matrix, and together with sheet filler, a multi-layered and more tortuous physical shielding barrier is constructed, which greatly prolongs the penetration path of water, oxygen and corrosive ions, thereby significantly improving the long-term shielding and anti-corrosion performance of the coating.
[0017] (3) By setting up a formulation system containing reactive diluents and specific additives, and combining the viscosity-reducing properties of hydroxyl-terminated hyperbranched polyester, a low application viscosity with high filler content was achieved. This gives the coating good leveling properties and application applicability, making it easy to prepare environmentally friendly coatings with high solids content and low VOCs, while ensuring that the coating surface is smooth, dense, and free of defects.
[0018] (4) By setting up component B, which is a compound of polyamide curing agent and silane coupling agent, the good flexibility and curing characteristics of polyamide curing agent on wet surfaces, and the effect of silane coupling agent to enhance the chemical bonding between the coating and the substrate interface, further synergistically improve the adhesion (especially wet adhesion), flexibility and environmental aging resistance of the coating, ensuring the long-term service reliability of the coating in harsh corrosive environments. Attached Figure Description
[0019] Figure 1 The preparation process flowchart provided by the present invention; Detailed Implementation The present invention will now be described in further detail with reference to the accompanying drawings and embodiments: A hyperbranched epoxy resin anti-corrosion coating is a two-component system, comprising component A and component B: Component A, by weight, includes the following components: Epoxy resin matrix: 40-70 parts, which is bisphenol A type epoxy resin E-51 (epoxy equivalent of about 184-190 g / eq); This resin has excellent adhesion, chemical corrosion resistance and mechanical properties, and is the core component of the coating film matrix, providing basic protective performance and structural support for the coating.
[0020] Hyperbranched polymer modifier: 5-20 parts, which is a hydroxyl-terminated hyperbranched polyester with a generation number of G2-G4 and a hydroxyl functionality of 8-32. The hydroxyl-terminated hyperbranched polyester is prepared by melt polycondensation reaction of trimethylolpropane as the core and 2,2-dimethylolpropionic acid. After addition, it can significantly improve the compatibility, leveling and flexibility of epoxy resin and the flexibility after curing, while improving the impermeability and corrosion resistance of the coating. Flaky filler: 10-30 parts, selected from at least one of mica iron oxide, glass flakes, or ferrophosphorus powder. Flaky filler is used to enhance the physical barrier effect of the coating, extend the penetration path of corrosive media, effectively block corrosive agents such as water and oxygen from contacting the substrate, and significantly improve the anti-corrosion performance of the coating.
[0021] Rust-preventive pigment: 5-15 parts, zinc phosphate; zinc phosphate can chemically react with the surface of the coated metal substrate to form a stable passivation film, inhibiting anodic dissolution of the metal. Simultaneously, its hydrolysis products can block coating pores, further enhancing the coating's rust-preventive ability. It should be noted that the metal substrates in this solution include, but are not limited to, common easily corroded metal materials such as carbon steel, low-alloy steel, and cast iron. After the coating is applied to the metal substrate surface and cured, zinc phosphate slowly releases phosphate ions, which react with iron ions on the metal substrate surface to form a dense iron phosphate passivation film, isolating the corrosive medium from contact with the metal substrate. At the same time, the hydrolysis products fill the internal pores of the coating, significantly reducing the coating's water permeability and air permeability.
[0022] Reactive diluent: 0-10 parts, selected from at least one of benzyl glycidyl ether, butyl glycidyl ether, or polyethylene glycol diglycidyl ether. The reactive diluent can adjust the viscosity of component A, improve the application performance of the coating, and participate in the curing reaction, preventing pinholes and other defects in the coating due to solvent evaporation.
[0023] Additives: 1-5 parts, including dispersant (0.5-2.0 parts), defoamer (0.2-1.0 parts), and leveling agent (0.3-2.0 parts); the dispersant is a polycarboxylate dispersant, the defoamer is an organosilicon defoamer, and the leveling agent is an acrylate leveling agent. The dispersant improves the dispersion stability of fillers and pigments in the resin matrix and prevents agglomeration; the defoamer eliminates bubbles generated during paint preparation and application, ensuring a smooth coating surface; the leveling agent allows the paint to quickly level after application, forming a smooth and uniform paint film.
[0024] Component B is the curing agent, with polyamide as its core component and a coupling agent added. The coupling agent is silane coupling agent KH-550, added at 0.5-2.0% of the weight of the polyamide curing agent. The silane coupling agent possesses both organic and inorganic affinity groups, enhancing the interfacial bonding between components A and B, while also improving the adhesion of the coating to the metal substrate and enhancing the coating's water resistance and weather resistance. Components A and B are mixed in a weight ratio of 4:1 to 5:1.
[0025] A method for preparing a hyperbranched epoxy resin anticorrosive coating, used in any one of claims 1 to 5, comprising the following steps: (1) Preparation of component A: Step a: Premixing Add the formulated amount of epoxy resin matrix (bisphenol A type epoxy resin E-51) and hyperbranched polymer modifier into the reactor, control the stirring speed at 200-300 r / min, and the temperature at 60-75℃, and stir and mix at a constant temperature and speed for 30-60 minutes to obtain a uniform modified epoxy resin base material. The preparation method of the hyperbranched polymer modifier is as follows: Trimethylolpropane and excess 2,2-dimethylolpropionic acid are added to the reaction apparatus. The molar ratio of trimethylolpropane to 2,2-dimethylolpropionic acid is 1:(8-40), adjusted according to the generation (G2-G4) of the target product. 0.5%-1.5% of p-toluenesulfonic acid is added as an esterification catalyst. Under continuous nitrogen flow (flow rate 0.5-1.0 L / min), the material is heated to 135-150℃ for melt polycondensation. The water generated in the reaction is distilled off through a condenser. During the reaction, the acid value of the system is continuously monitored to control the reaction endpoint. Samples are taken approximately every hour, and the acid value (AV) of the system is monitored using the standard potassium hydroxide-ethanol titration method. The reaction endpoint can be determined by adjusting the initial molar ratio of the reactants and controlling the reaction until the acid value of the system decreases to the corresponding preset range (e.g., for G2 generation products, the target acid value range is 12-18 mgKOH / g; for G3 generation products, the target acid value range is 8-12 mgKOH / g; for G4 generation products, the target acid value range is 5-8 mgKOH / g). After reaching the endpoint, heating is stopped and the mixture is cooled to obtain the terminal hydroxyl hyperbranched polyester of the target generation (G2-G4). Nitrogen protection prevents the raw materials from oxidizing and deteriorating at high temperatures, while p-toluenesulfonic acid efficiently catalyzes the esterification reaction, shortening the reaction time.
[0026] The reaction apparatus is a four-necked flask equipped with a mechanical stirrer, a thermocouple thermometer, a nitrogen inlet pipe, and a condenser. The stirring speed of the mechanical stirrer can be adjusted to 200-400 r / min, the temperature measurement range of the thermocouple thermometer is 0-300℃, the outlet of the nitrogen inlet pipe extends below the liquid surface to ensure that the nitrogen fully removes oxygen, and the condenser is used to separate and collect the water generated in the reaction.
[0027] Step b: Grinding and dispersing The modified epoxy resin matrix obtained in step a, along with all the flake fillers, anti-rust pigments, and dispersants, is added to a high-speed disperser for pre-dispersion treatment. The stirring speed is controlled at 800-1200 r / min, and the stirring time is 15-25 minutes, so that the solid components are initially dispersed in the resin matrix, forming a mixture without obvious large particle agglomeration. Subsequently, the pre-dispersed mixture is transferred to a three-roll mill for grinding until the material fineness is ≤50μm, resulting in a uniform and stable slurry. Grinding to this fineness ensures that the fillers and pigments are fully dispersed, avoiding surface defects or reduced protective performance of the coating due to excessively large particles.
[0028] Step c: Mixing paint Transfer the slurry obtained in step b to a paint mixing tank, add the prescribed amounts of defoamer, leveling agent and reactive diluent and mix. Stir at 300-500 r / min for 10-20 minutes at room temperature to ensure that the additives are fully dispersed. Finally, filter the mixture through a 200-300 mesh stainless steel filter to remove incompletely ground coarse particles and impurities to obtain component A. (2) Preparation of component B: Add polyamide curing agent to a low-speed mixer, add silane coupling agent KH-550 (0.5-2.0% of the weight of polyamide curing agent) in proportion, and stir at 200-300 r / min for 5-10 minutes until the mixture is uniform (the low-speed mixer can ensure that the coupling agent and polyamide curing agent are uniformly dispersed); then use a 100-150 mesh stainless steel filter screen for normal pressure filtration to remove trace solid impurities that may exist in the coupling agent or a small amount of agglomeration of polyamide curing agent, and discharge the filtered material to obtain the finished component B.
[0029] When using, mix component A and component B in a weight ratio of 4:1 to 5:1. After stirring evenly, the coating can be applied. After coating, you can choose to cure at room temperature (25℃, 72 hours) or heat to cure (60-80℃, 2-4 hours) to form a hyperbranched epoxy resin coating with excellent anti-corrosion properties.
[0030] The specific implementation process is as follows: Example 1: Preparation of hyperbranched epoxy resin anti-corrosion coating 1. Raw materials and formula Component A, by weight, consists of the following raw materials: Bisphenol A type epoxy resin E-51 (epoxy equivalent approximately 184-190 g / eq): 55 parts Hydroxyl-terminated hyperbranched polyester (G3 generation, self-made, hydroxyl value approximately 280 mg KOH / g): 15 parts Mica iron oxide (325 mesh): 20 parts Zinc phosphate: 5 parts Benzyl glycidyl ether (reactive diluent): 5 parts Polycarboxylate dispersant (BYK-163): 0.8 parts Organosilicon defoamer (BYK-066N): 0.3 parts Acrylic leveling agent (BYK-331): 0.4 parts Component B is composed of the following raw materials: Polyamide curing agent (amine value approximately 220 mg KOH / g): 100 parts Silane coupling agent KH-550: 1.5 parts (i.e., 1.5% of the weight of the curing agent) The construction mixing weight ratio of component A to component B is 4.5:1.
[0031] 2. Preparation method (1) Synthesis of hydroxyl-terminated hyperbranched polyesters In a 1000 mL four-necked flask equipped with a mechanical stirrer, thermocouple, nitrogen inlet tube (with the outlet extending below the liquid surface), and condenser, 12.0 g of trimethylolpropane (TMP) and 160.0 g of 2,2-dimethylolpropionic acid (DMPA) (molar ratio TMP:DMPA = 1:12), along with 1.72 g of p-toluenesulfonic acid as a catalyst (1.0% of the total reactant mass), were added. Under continuous nitrogen purging (flow rate 0.8 L / min), the mixture was slowly heated to 140 °C, and stirring was started (300 r / min) to initiate a melt polycondensation reaction. The generated water was distilled off using a condenser. During the reaction, samples were taken every hour, and the acid value (AV) of the system was determined according to GB / T 1668-2008 standard. When the reaction proceeded for approximately 8 hours and the acid value dropped to 10 mg KOH / g, heating was stopped, the mixture was cooled, and the product was discharged, yielding a pale yellow, viscous G3 generation terminal hydroxyl hyperbranched polyester.
[0032] (2) Preparation of component A Premixing: 55 parts of epoxy resin E-51 and 15 parts of the self-made hydroxyl-terminated hyperbranched polyester were added to a heatable reactor and stirred at 250 r / min at 65°C for 40 minutes to obtain a uniform modified epoxy resin base.
[0033] Grinding and Dispersion: The modified epoxy resin base material was transferred to a high-speed disperser, and 20 parts of mica iron oxide, 5 parts of zinc phosphate, and 0.8 parts of dispersant were added. The mixture was pre-dispersed at 1000 r / min for 20 minutes. The material was then transferred to a three-roll mill and ground three times until the fineness measured by a scraper fineness gauge was ≤40 μm, resulting in a uniform slurry.
[0034] Paint mixing: Transfer the obtained slurry to a mixing tank. While stirring at low speed (300-500 rpm), add 0.3 parts of defoamer, 0.4 parts of leveling agent, and 5 parts of benzyl glycidyl ether in sequence (other reactive diluents can be added according to the same process to achieve the same effect), and stir for 15 minutes. Finally, filter through a 250-mesh stainless steel filter to obtain component A.
[0035] (3) Preparation of component B Add 100 parts of polyamide curing agent and 1.5 parts of silane coupling agent KH-550 to a container, stir at 250 r / min for 8 minutes until uniformly mixed, and then filter through a 120 mesh filter to obtain component B.
[0036] (4) Coating preparation and curing The prepared component A and component B were mixed at a weight ratio of 4.5:1, stirred for 3 minutes, and cured for 15 minutes before being brushed onto the surface of a sandblasted (Sa2.5 grade) Q235 steel plate. The coating was cured for 7 days at 25±2℃ and 50±5% relative humidity to form a test sample with a dry film thickness of approximately 120±10μm.
[0037] Comparative Example 1 (Traditional Epoxy Coating) To verify the beneficial effects of the present invention, Comparative Example 1 was set up. Its formulation and preparation method differed from Example 1 only in that: 15 parts of terminal hydroxyl hyperbranched polyester were not added to component A, and this weight was made up with an equal amount of epoxy resin E-51 (i.e., the total amount of epoxy resin used in the comparative example was 70 parts, without any hyperbranched polyester). All other raw materials, amounts, and all preparation, application, and curing process parameters were exactly the same as in Example 1.
[0038] Performance testing and effect analysis The coatings obtained in Example 1 and Comparative Example 1 were subjected to performance tests, and the results are compared in the table below: Conclusion: The above examples and comparative data fully demonstrate that by introducing a terminal hydroxyl hyperbranched polyester with a specific structure, the present invention successfully solves the problem of poor toughness, high viscosity and long-term protection of traditional epoxy coatings, and obtains a high-performance anti-corrosion coating with excellent comprehensive performance.
[0039] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.
Claims
1. A hyperbranched epoxy resin anti-corrosion coating, characterized in that, It is a two-component system, consisting of component A and component B: Component A, by weight, includes the following components: Epoxy resin matrix: 40-70 parts; Hyperbranched polymer modifier: 5-20 parts; the hyperbranched polymer modifier is a hydroxyl-terminated hyperbranched polyester with a generation number of G2 to G4 and a hydroxyl functionality of 8-32; the hydroxyl-terminated hyperbranched polyester is prepared by melt polycondensation reaction of trimethylolpropane as the core and 2,2-dimethylolpropionic acid. Flake packing: 10-30 parts; Rust-preventive pigment: 5-15 parts; Reactive diluent: 0-10 parts; Additives: 1-5 parts; Component B is a curing agent, specifically a polyamide curing agent; wherein, components A and B are configured to be mixed in a weight ratio of 4:1 to 5:
1.
2. The hyperbranched epoxy resin anti-corrosion coating as described in claim 1, characterized in that: The epoxy resin matrix is bisphenol A type epoxy resin.
3. The hyperbranched epoxy resin anti-corrosion coating as described in claim 1, characterized in that: The sheet-like filler is selected from at least one of mica iron oxide, glass flakes, or ferrophosphorus powder.
4. The hyperbranched epoxy resin anti-corrosion coating as described in claim 1, characterized in that: The rust-preventive pigment is zinc phosphate.
5. The hyperbranched epoxy resin anti-corrosion coating as described in claim 1, characterized in that: The additives include dispersants, defoamers, and leveling agents.
6. A method for preparing a hyperbranched epoxy resin anticorrosive coating, used in any one of claims 1 to 5, characterized in that, Includes the following steps: (1) Preparation of component A: a. Premixing: The epoxy resin matrix and the hyperbranched polymer modifier are stirred and mixed at 60-75°C for 30-60 minutes to obtain the modified epoxy resin base material; b. Grinding and dispersing: The modified epoxy resin base material obtained in step a is pre-dispersed with all the flake fillers, anti-rust pigments and dispersants, and then ground to a fineness of ≤50μm to obtain a slurry; c. Paint mixing: Add the defoamer, leveling agent and reactive diluent to the slurry obtained in step b, stir evenly and filter to obtain component A; (2) Preparation of component B: The polyamide curing agent and coupling agent are mixed evenly to obtain component B.
7. The method for preparing a hyperbranched epoxy resin anti-corrosion coating as described in claim 6, characterized in that, In step a, the preparation method of the hyperbranched polymer modifier is as follows: under nitrogen protection and in the presence of an esterification catalyst, trimethylolpropane and excess 2,2-dimethylolpropionic acid are subjected to a melt polycondensation reaction at 135-150°C. The reaction endpoint is controlled by monitoring the acid value of the system to obtain a terminal hydroxyl hyperbranched polyester of the target generation. The esterification catalyst is p-toluenesulfonic acid.
8. The method for preparing a hyperbranched epoxy resin anti-corrosion coating as described in claim 6, characterized in that, In step b, the grinding is performed using a three-roll mill.
9. The method for preparing a hyperbranched epoxy resin anticorrosive coating as described in claim 6, characterized in that, In step c, the active diluent is selected from at least one of benzyl glycidyl ether, butyl glycidyl ether, or polyethylene glycol diglycidyl ether.
10. The method for preparing a hyperbranched epoxy resin anti-corrosion coating as described in claim 6, characterized in that, In step (2), the coupling agent is a silane coupling agent, and its addition amount is 0.5-2.0% of the weight of the polyamide curing agent.