Anticorrosive waxy colloidal paint and wet and water carrying application method thereof

Abstract

The present application belongs to the technical field of marine engineering anticorrosion materials, and particularly relates to a kind of anticorrosive waxy colloidal paint and its wet and water construction method. In view of the problems that the existing anticorrosive coating is difficult to construct under the condition of wet and water, and the hydrophobic anticorrosive ability is insufficient, the present application proposes a kind of solvent-free two-component system, which includes component A and component B. The component A is composed of microcrystalline wax treated by KH-560 surface modification, silicone compounded epoxy resin, hydrophobic reinforcing filler, thixotropic agent, anticorrosive filler and anti-settling agent. The component B includes curing agent and curing accelerator. The low surface energy wax phase structure constructed by microcrystalline wax, combined with the stable crosslinking network formed by silicone compounded epoxy resin, makes the coating have both hydrophobic anticorrosive performance and mechanical properties. The present application also provides a wet and water construction method, which can be constructed under the condition of wet and water. The present application can improve the anticorrosive performance and construction adaptability under the complex environment of the splash zone of offshore platform.

Description

Technical Field

[0001] This invention belongs to the technical field of marine engineering anti-corrosion materials, specifically relating to an anti-corrosion waxy colloidal coating and its application method under wet conditions. Background Technology

[0002] Marine engineering equipment operates in environments characterized by high salinity, high humidity, and cyclical wet-dry cycles. The splash zone of offshore platforms, in particular, is one of the most severely corroded areas due to constant seawater erosion, salt spray deposition, moisture exposure, and wet-dry cycles. To extend the service life of offshore platform steel structures, organic anti-corrosion coatings are typically used to protect the substrate surface. Epoxy resin coatings are widely used in the field of corrosion protection for marine engineering structures due to their excellent adhesion, chemical corrosion resistance, and high mechanical strength.

[0003] However, traditional epoxy resin anti-corrosion coatings used in marine engineering still have certain shortcomings in application. On the one hand, the splash zone of offshore platforms is constantly subjected to seawater erosion, moisture exposure, and periodic wet-dry cycles. Moisture and salt ions can easily penetrate into the coating through micropores and interface defects, ultimately leading to a decrease in the coating's density and anti-corrosion performance, and subsequently causing substrate corrosion. Simultaneously, when traditional solvent-based anti-corrosion coatings are applied in humid or wet environments, the adhesion between the coating and the substrate is easily affected by a water film, making it difficult to meet the requirements of wet construction in marine engineering. On the other hand, existing epoxy resin anti-corrosion coatings typically rely on a high cross-linking density structure to improve corrosion resistance. However, a high cross-linking structure can reduce the coating's flexibility, causing cracks to form under long-term wet-dry cycles and seawater erosion. Furthermore, ordinary epoxy resins have a high surface energy, making it easy for seawater and salt spray to wet and adhere to the coating surface, hindering effective hydrophobic barrier properties. Therefore, simply increasing the resin cross-linking strength cannot simultaneously guarantee the coating's anti-corrosion performance, impact resistance, and environmental adaptability.

[0004] Currently, to improve the water resistance and flexibility of epoxy anti-corrosion coatings, modifications such as organosilicon modification, nanofiller reinforcement, or hydrophobic material compounding are commonly used. For example, organosilicon compounding with epoxy resin can reduce the surface energy of the resin system and improve its flexibility, but excessive introduction of organosilicon structures can lead to a decrease in the mechanical strength of the coating. On the other hand, using wax-based hydrophobic materials to construct low surface energy structures can improve the water repellency of the coating, but the compatibility between wax phase materials and epoxy resin is poor, easily causing phase separation and internal defects in the coating. Therefore, existing technologies still struggle to achieve the synergistic construction of hydrophobic protective structures and high-strength cross-linked networks.

[0005] To address the problem of poor adhesion and insufficient hydrophobic and anti-corrosion capabilities caused by the difficulty of wetting the interface of existing anti-corrosion coatings under humid conditions, it is of great application value to develop a coating with high performance in waterproofing and corrosion resistance that can be used in the field of marine engineering. Summary of the Invention

[0006] The purpose of this invention is to provide an anti-corrosion waxy colloidal coating and its application method under wet conditions. The anti-corrosion waxy colloidal coating is a solvent-free two-component system, comprising two components, A and B. Component A includes: microcrystalline wax surface-modified with KH-560, silicone-based epoxy resin, hydrophobic reinforcing filler surface-treated with HMDS, hydrophilic fumed silica thixotropic agent, anti-corrosion filler, and anti-settling agent. Component B includes: modified cycloaliphatic amine wet-surface curing agent and curing accelerator. The silicone-based epoxy resin in component A is prepared by compounding terminal epoxy-terminated polydimethylsiloxane and E51 bisphenol A type epoxy resin at a mass ratio of 7-9:1-3. During application, components A and B are mixed at a mass ratio of 100:18-30 for curing. After curing, the coating forms a composite protective coating with a wax phase structure and a resin cross-linking structure. A corrosion-resistant waxy colloidal coating was prepared that can adapt to the wet and dry cycle environment of the splash zone, has the ability to be applied while wet, and also has long-term corrosion resistance and mechanical stability.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A corrosion-resistant waxy colloidal coating and its application method under wet conditions, comprising the following steps: Unless otherwise specified, the parts in this invention refer to parts by mass.

[0008] The anti-corrosion waxy colloidal coating A component, by weight, includes the following components: 25-35 parts of microcrystalline wax modified with KH-560, 40-50 parts of silicone-based epoxy resin, 5-10 parts of hydrophobic reinforcing filler treated with HMDS, 1-3 parts of hydrophilic fumed silica thixotropic agent, 10-20 parts of anti-corrosion filler, and 0.5-1.5 parts of anti-settling agent; B component, by weight, includes the following components: 90-98 parts of modified cycloaliphatic amine wet surface curing agent and 2-10 parts of curing accelerator.

[0009] Preparation of coating: The microcrystalline wax, silicone-modified epoxy resin, hydrophobic reinforcing filler, thixotropic agent, anti-corrosion filler, and anti-settling agent of component A are added to a high-speed disperser in the above proportions. The mixture is dispersed and stirred at 1500 r / min for 30 minutes at room temperature and ground until uniform to obtain component A. The curing agent and curing accelerator of component B are added to a mixing tank in the above proportions and stirred at 600 r / min for 15 minutes until uniform to obtain component B.

[0010] Preferably, the organosilicon compounded epoxy resin in component A is prepared by compounding terminal epoxy-terminated polydimethylsiloxane and E51 bisphenol A type epoxy resin in a mass ratio of 7-9:1-3. The preparation method is as follows: the terminal epoxy-terminated polydimethylsiloxane and E51 bisphenol A type epoxy resin are compounded in a mass ratio of 7-9:1-3 and put into a mixing vessel equipped with a heating jacket, heated to 60°C, stirred and dispersed at 600 r / min for 30 minutes, and cooled to obtain the organosilicon compounded epoxy resin. The prepared organosilicon compounded epoxy resin is tested, and its viscosity at 25°C is tested to evaluate the processing performance of the compound system. At the same time, the stability of the compound system during storage is observed, and whether stratification, sedimentation or obvious phase separation occurs is recorded to ensure the stability of its component state and performance.

[0011] Preferably, the anti-corrosion filler is composed of ultrafine zinc phosphate, mica iron oxide and barium sulfate; the mass ratio of ultrafine zinc phosphate, mica iron oxide and barium sulfate is 0.8-1.2:1.8-2.2:0.8-1.2.

[0012] Preferably, the microcrystalline wax is No. 85 petroleum microcrystalline wax with the following physicochemical parameters: melting point of 85℃, oil content of less than 0.5%, and the No. 85 petroleum microcrystalline wax is mainly composed of high isoparaffins and cycloalkanes, accounting for more than 70%. The specific preparation steps are as follows: First, the No. 85 petroleum microcrystalline wax is heated and melted, an emulsifier and preheated deionized water are added, and a microcrystalline wax emulsion is obtained through high-speed shear emulsification. Simultaneously, 4% (by mass) of KH-560 is added to an ethanol-water solvent with a volume ratio of 3:7, the pH is adjusted with glacial acetic acid, and activation hydrolysis is performed to obtain an active silanol (-SiO-H) solution. Subsequently, the above silanol solution is added dropwise to the microcrystalline wax emulsion at a constant rate, and the reaction is carried out under constant temperature and mechanical stirring conditions. After the reaction is completed, the wax is cooled, filtered, washed, dried, ground, and sieved to obtain the microcrystalline wax with KH-560 surface modification treatment.

[0013] Preferably, the anti-settling agent is hydrogenated castor oil micropowder with the following physicochemical parameters: melting point 85℃, average particle size 15μm, and density 1.0g / cm³. 3 .

[0014] Preferably, the hydrophobic reinforcing filler is hydrophobic fumed silica with the following physicochemical parameters: specific surface area 180 m². 2 / g, the surface is chemically treated with hexamethyldisilazane (HMDS), and its contact angle is greater than 110°; the preparation includes the following steps: 100g of a material with a specific surface area of ​​180m² 2 / g of hydrophilic silica was added to a sealed reactor, and nitrogen gas was introduced three times at room temperature for purging. The mixture was stirred at 800 r / min and 1.5 mL of deionized water was sprayed in via atomization. The stirring was continued for 20 minutes. Then, 15g of hexamethyldisilazane was sprayed in uniformly and the temperature was raised to 130℃ for 2 hours. After the reaction was completed, the temperature was raised to 160℃ and the vacuum was drawn to -0.09 MPa for 1 hour for degassing. Finally, nitrogen gas was introduced and the mixture was cooled to 30℃ to obtain a hydrophobic reinforced filler with a water contact angle greater than 110°.

[0015] Preferably, the curing agent is a modified alicyclic amine wet surface curing agent with the following physicochemical parameters: active hydrogen equivalent: 120 g / eq, viscosity at 25°C: 1500 mPa·s, amine value: 320 mg KOH / g; the curing accelerator is 2,4,6-tris(dimethylaminomethyl)phenol with the following physicochemical parameters: purity greater than 98%, density 0.975 g / cm³. 3 .

[0016] Preferably, the thixotropic agent is hydrophilic fumed silica with the following physicochemical parameters: silica purity ≥ 99.8%, specific surface area 200 m². 2 The sample has a particle size of 15 nm, a bulk density of 60 g / L, and a surface rich in high-density silanol groups (-SiO-H). The preparation method is as follows: Liquid silicon tetrachloride is heated to vaporize, mixed with hydrogen and air in a 1:2:1 molar ratio, and introduced into a combustion furnace. A high-temperature gas-phase hydrolysis reaction is carried out in a 1000℃ flame. The generated aerosol is cooled by the airflow and condenses into nano-sized particles, which are then collected by a cyclone separator and sent to a deacidification furnace. In the deacidification furnace, 400℃ humid hot air is continuously introduced for stripping and deacidification to remove the translation byproduct hydrogen chloride adsorbed on the particle surface. Finally, the sample is cooled to room temperature to obtain the final product.

[0017] Application method of anti-corrosion waxy colloidal coatings while the coating is wet: S1. Substrate Treatment: Surface treatment is performed on the area to be treated to remove surface contaminants, and the treatment level of the area to be treated reaches Sa2. The parameters were measured, including surface profile / roughness, soluble salts, dust, substrate temperature, ambient temperature and humidity, and dew point difference. S2. Mixing and curing the coating: Mechanically mix component A and component B at a mass ratio of 100:18-30, and let it stand and cure at 20-30°C for 10-15 minutes; S3. Wet application: Application is carried out on the substrate surface when there is an adhering water film, a damp state, or a periodically water-exposed environment. The mixed coating is applied to the substrate surface by airless spraying, brushing, or roller coating. S4. Thick film formation: control the wet film thickness to be 510-1050μm; the dry film thickness after room temperature curing is 500-1000μm.

[0018] Preferably, the surface treatment level in S1 reaches Sa2. The grade is determined by visual comparison with the standard sample in GB / T 8923.1-2011. That is, when observed without magnification, there is no visible oil or dirt on the surface of the substrate, and the oxide scale, rust, coating and impurities have been basically removed. The only remaining slight traces are slight spots or streaks.

[0019] Preferably, a high-pressure airless spraying device with a nozzle diameter of 0.02 inches and a working pressure of 20 MPa is used to spray the mixed coating onto the damp steel structure surface with a water film.

[0020] Preferably, before construction, ensure the substrate surface remains continuously moist and record the substrate temperature, ambient temperature, and relative humidity. Use a high-pressure airless sprayer, controlling the spray pressure at 20 MPa and the spray distance at 40 cm, applying multiple cross-coats to form a 750 μm thick coating. During construction, monitor the dry film thickness and observe the coating surface for defects such as pinholes, runs, and craters.

[0021] Preferably, to ensure the curing stability of the coating system, equivalent calculations are performed during the preparation process based on the detection parameters of the epoxy resin component and the curing agent component. The number of epoxy groups in the epoxy resin component is calculated according to the mass of each epoxy resin component added and the epoxy equivalent. The number of active hydrogens in the curing agent component is calculated according to the added mass and the active hydrogen equivalent. The mixing ratio of components A and B is then determined based on these calculations. Before use, different batches of raw materials need to be tested for indicators such as epoxy equivalent, active hydrogen equivalent, amine value, and viscosity to ensure stable curing and coating performance.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention uses microcrystalline wax that has been surface modified with KH-560, which gives the microcrystalline wax good surface hydrophobicity and anti-adhesion ability. After KH-560 modification, the microcrystalline wax is combined in the epoxy resin crosslinking network and dispersed in a direction to the coating surface, increasing the water contact angle to more than 115°. This can effectively repel seawater in the splash zone and reduce the deposition of salt and the adhesion of other pollutants.

[0023] 2. This invention uses terminal epoxy-terminated polydimethylsiloxane and E-51 bisphenol A type epoxy resin in a mass ratio of 7-9:1-3 to prepare an organosilicon composite epoxy resin. This significantly improves the toughness and wet adhesion of the coating. The introduction of flexible segments from the terminal epoxy-terminated polydimethylsiloxane effectively releases internal stress during the curing of the anti-corrosion thick film and under alternating environments, greatly enhancing the coating's anchoring strength and crack resistance on damp substrates.

[0024] 3. This invention uses ultrafine zinc phosphate, mica iron oxide, and barium sulfate mixed in a mass ratio of 0.8-1.2:1.8-2.2:0.8-1.2 to form an anti-corrosion filler. Zinc phosphate mainly improves the anti-corrosion ability of the coating through a slow-release effect; mica iron oxide utilizes its lamellar structure to reduce the diffusion path of corrosive media in the coating; and barium sulfate, as a stabilizing filler component, can improve the density of the coating structure. The three fillers have complementary functions, and the overall protective performance of the coating is improved through a reasonable combination. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating the manufacturing process of the anti-corrosion waxy colloidal coating in this invention.

[0026] Figure 2 This is a dual Y-axis diagram showing the electrochemical low-frequency impedance modulus and the adhesion of the anti-corrosion waxy colloidal coating by pull-off method in this invention. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below through some embodiments and experimental examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] Reference Figure 1 The process flow diagram shown illustrates that this invention provides an anti-corrosion waxy colloidal coating and its application method under wet conditions. The technical solution is as follows: Example 1 1. Raw materials and proportions The solvent-free two-component anti-corrosion waxy colloidal coating includes component A and component B. Component A, by mass parts, includes the following components: 30 parts of microcrystalline wax surface-modified with KH-560, 45 parts of silicone-based epoxy resin, 7 parts of hydrophobic reinforcing filler surface-treated with HMDS, 2 parts of hydrophilic fumed silica thixotropic agent, 17 parts of anti-corrosion filler, and 1 part of anti-settling agent.

[0029] Component B, by mass, includes the following components: 94 parts of modified cycloaliphatic amine wet surface curing agent and 6 parts of curing accelerator. Component A and component B are mixed at a mass ratio of 25:6.

[0030] The specific parameters of the raw materials in the coating formulation are as follows: The microcrystalline wax used is No. 85 petroleum microcrystalline wax, with the following physicochemical parameters: melting point of 85℃, oil content of less than 0.5%, and the No. 85 petroleum microcrystalline wax is mainly composed of high isoparaffins and cycloalkanes, accounting for more than 70%.

[0031] The hydrophobic reinforcing filler uses hydrophobic fumed silica with the following physicochemical parameters: specific surface area 180 m². 2 / g, the surface is chemically treated with hexamethyldisilazane (HMDS), and its contact angle is greater than 110°.

[0032] The thixotropic agent is hydrophilic fumed silica, with the following physicochemical parameters: silica purity ≥ 99.8%, specific surface area 200 m² / g. 2 It has an average particle size of 15 nm and a bulk density of 60 g / L, and its surface is rich in high-density silanol groups (-SiO-H).

[0033] The anti-settling agent uses hydrogenated castor oil micropowder with the following physicochemical parameters: melting point 85℃, average particle size 15μm, and density 1.0g / cm³. 3 .

[0034] The silicone-based epoxy resin was prepared by compounding terminally epoxy-terminated polydimethylsiloxane and E-51 bisphenol A type epoxy resin at a mass ratio of 8:2. Both ends of the terminally epoxy-terminated polydimethylsiloxane molecular chain contain epoxy groups capable of undergoing ring-opening reactions with amine curing agents. The physicochemical parameters of the terminally epoxy-terminated polydimethylsiloxane are: epoxy equivalent: 600 g / eq, kinematic viscosity at 25℃: 100 mm³ / h. 2 / s; Physicochemical parameters of E-51 bisphenol A type epoxy resin: epoxy value: 0.51eq / 100g, viscosity at 25℃: 13000mPa.s.

[0035] The curing agent is a modified alicyclic amine wet surface curing agent with the following physicochemical parameters: active hydrogen equivalent: 120 g / eq, viscosity at 25℃: 1500 mPa.s, and amine value: 320 mg KOH / g.

[0036] The curing accelerator is 2,4,6-tris(dimethylaminomethyl)phenol, with the following physicochemical parameters: purity greater than 98%, density 0.975 g / cm³. 3 .

[0037] The anti-corrosion filler is composed of ultrafine zinc phosphate, mica iron oxide and barium sulfate mixed in a mass ratio of 1:2:1.

[0038] 2. Modification and preparation steps of microcrystalline wax S1. Preparation of microcrystalline wax emulsion: Weigh 100g of No. 85 petroleum microcrystalline wax solid particles with a melting point of 85℃ and an oil content of 0.3%, place them in a three-necked flask and heat them in a water bath to 95℃, and continue heating for 30 minutes to completely melt the microcrystalline wax; then add 5g of fatty alcohol polyoxyethylene ether composite emulsifier to the molten microcrystalline wax, and slowly add 200mL of deionized water preheated to 85℃; then start a high-speed shear emulsifier, set the shearing speed to 4000r / min and continue shearing and dispersing for 35 minutes. After shearing, quickly cool down to 30℃ to obtain the microcrystalline wax emulsion.

[0039] S2. Hydrolysis and activation of silane coupling agent KH-560: Measure 30 mL of anhydrous ethanol and 70 mL of deionized water to prepare an ethanol-water solvent with a volume ratio of 3:7, place it in a beaker and stir magnetically at a speed of 400 r / min; then weigh 4 g of KH-560 and slowly add it dropwise to the above ethanol-water solvent, and adjust the pH of the system to 4 with glacial acetic acid. Continue stirring at room temperature of 25°C for 30 minutes to hydrolyze and activate the methoxy group in KH-560 to fully hydrolyze and convert it into an active silanol (-SiO-H) solution.

[0040] S3. Modification of microcrystalline wax: The prepared KH-560 solution was placed in a constant pressure dropping funnel and slowly added to the microcrystalline wax emulsion at a constant rate of 2 mL / min. The reaction system was then heated in a constant temperature water bath at 45°C while mechanically stirred at a speed of 600 r / min for 2 hours.

[0041] S4. Separation, washing and drying: After the reaction is completed, the mixture is cooled to room temperature and the solid product is collected by vacuum filtration using a Buchner funnel. The solid product is then washed three times with a 50% ethanol solution to remove unreacted free KH-560 and residual emulsifier. Finally, the solid product is dried in a vacuum drying oven at 60°C until constant weight. After drying, it is ground and passed through a 100-mesh sieve to obtain the microcrystalline wax with KH-560 surface modification treatment.

[0042] 3. Preparation of hydrophobic reinforcing filler: 100g of filler with a specific surface area of ​​180m² was prepared. 2 / g of hydrophilic silica was added to a sealed reactor, and nitrogen gas was introduced three times at room temperature for purging. The reactor was stirred at 800 r / min and 1.5 mL of deionized water was sprayed in via atomization. The stirring was continued for 20 minutes. Then, 15g of hexamethyldisilazane was sprayed in uniformly and the temperature was raised to 130℃ for 2 hours. After the reaction was completed, the temperature was raised to 160℃ and the vacuum was drawn to -0.09 MPa for 1 hour for degassing. Finally, nitrogen gas was introduced and the reactor was cooled to 30℃ to obtain a hydrophobic reinforced filler with a water contact angle greater than 110°.

[0043] 4. Preparation of thixotropic agent (hydrophilic fumed silica): Liquid silicon tetrachloride is heated to vaporize it, mixed with hydrogen and air in a molar ratio of 1:2:1 and introduced into a combustion furnace. A high-temperature gas-phase hydrolysis reaction is carried out in a flame at 1000°C. The generated aerosol is cooled by the airflow and condenses into nano-sized particles, which are then collected by a cyclone separator and sent to a deacidification furnace. In the deacidification furnace, humid hot air at 400°C is introduced for continuous stripping and deacidification to remove the translation byproduct hydrogen chloride adsorbed on the surface of the particles. Finally, the mixture is cooled to room temperature to obtain the thixotropic agent.

[0044] 5. Preparation of Organosilicon Composite Epoxy Resin: Terminally epoxy-based polydimethylsiloxane and E-51 bisphenol A type epoxy resin were compounded at a mass ratio of 8:2 and added to a mixing vessel equipped with a heating mantle. The mixture was heated to 60°C and stirred at 600 rpm for 30 minutes. After cooling, the organosilicon composite epoxy resin was obtained. The prepared organosilicon composite epoxy resin was tested. Its viscosity at 25°C was measured to evaluate the processing performance of the composite system. Simultaneously, the stability of the composite system during storage was observed, and the occurrence of stratification, sedimentation, or significant phase separation was recorded to ensure the stability of its component state and performance.

[0045] 6. Preparation of the curing agent: The curing agent was prepared using a mixture of 40 parts 1,3-BAC, 15 parts E-51 epoxy resin, and 45 parts benzyl alcohol. First, 15 parts epoxy resin and 25 parts benzyl alcohol were weighed and placed in a three-necked flask equipped with a stirrer and thermometer. After stirring, the mixture was heated to 70°C. Then, 40 parts 1,3-BAC and 20 parts benzyl alcohol were weighed and placed in a four-necked flask equipped with a stirrer, thermometer, and constant-pressure dropping funnel. After stirring, the mixture was heated to 70°C. The previously prepared epoxy resin mixture was then poured into the constant-pressure dropping funnel and slowly added dropwise to the four-necked flask at a uniform rate. Finally, the mixture was kept at 70°C for 2 hours. After the reaction, it was allowed to cool naturally to obtain the curing agent. The performance of the prepared curing agent was tested to ensure that its active hydrogen equivalent, viscosity at 25°C, and amine value were within the specified range. Only those that passed the tests could be used as component B.

[0046] 7. Preparation of coating: Add the microcrystalline wax with KH-560 surface modification treatment, organosilicon compound epoxy resin, hydrophobic reinforcing filler, thixotropic agent, anti-corrosion filler, and anti-settling agent of component A to a high-speed disperser in the above proportions, disperse and stir at 1500 r / min for 30 minutes at room temperature, and grind evenly to obtain component A; add the curing agent and curing accelerator of component B to a mixing tank in the above proportions, stir at 600 r / min for 15 minutes, and stir evenly to obtain component B.

[0047] 8. Construction methods with wet surfaces: S1. Substrate Treatment: Select carbon steel structural test plates from offshore platforms and perform sandblasting to remove surface rust, salt, and contaminants, achieving a surface treatment grade of Sa2. The parameters were measured, including surface profile / roughness, soluble salts, dust, substrate temperature, ambient temperature and humidity, and dew point difference.

[0048] S2. Mixing and maturing of component A and component B: Mix component A and component B at a mass ratio of 25:6, mechanically stir evenly for 5 minutes at a speed of 600 r / min using a pneumatic explosion-proof mixer, and then let it stand at 25°C for 10 minutes to allow the modified microcrystalline wax and epoxy resin in the system to form a stable composite dispersion system.

[0049] S3. Wet construction: Simulating the splash zone environment of an offshore platform, a continuous visible water film is formed by artificial spraying on the surface of a carbon steel test plate. The mixed coating is then sprayed onto the damp steel structure surface with the water film using a high-pressure airless spraying device with a nozzle diameter of 0.02 inches and a working pressure of 20 MPa.

[0050] S4. Heavy-duty anti-corrosion thick film formation and curing: The thickness of each single layer and the total dry film is controlled by a multi-pass cross-spraying process to ensure that the dry film thickness after coating curing is stable at 750μm. Then, the coated test plate is placed in a simulated splash zone alternating humid and hot environment for room temperature curing.

[0051] Examples 2-7 differ from Example 1 in operating parameters, but the other process steps and the range of raw material selection are the same.

[0052] The specific changes in operating parameters are summarized in Table 1.

[0053] Table 1. Variations of Component A parameters in Examples 1-7 Table 2. Variations of component B parameters and mass ratio of components A and B in Examples 1-7 Comparative Example 1 Unlike Example 1, the microcrystalline wax in this comparative example was not treated with KH-560 for surface modification, but the remaining process parameters were the same as in Example 1. This was used to verify the necessity of KH-560 for surface modification of the microcrystalline wax.

[0054] Comparative Example 2 Unlike Example 1, this comparative example does not use silicone-based epoxy resin; instead, it uses ordinary E-51 bisphenol A type epoxy resin. All other process parameters are the same as in Example 1. This is used to verify the necessity of compounding terminal epoxy group polydimethylsiloxanes.

[0055] Comparative Example 3 Unlike Example 1, this comparative example uses a single anti-corrosion filler, that is, all three components in the anti-corrosion filler are replaced with a single component, namely 17 parts of ultrafine zinc phosphate. The remaining process parameters are the same as in Example 1. This is used to demonstrate the effect of the combined addition of the three components of the anti-corrosion filler.

[0056] Comparative Example 4 Unlike Example 1, this comparative example uses a single anti-corrosion filler, that is, all three components in the anti-corrosion filler are replaced with a single component, namely 17 parts of mica iron oxide. The remaining process parameters are the same as in Example 1. This is used to demonstrate the effect of the combined addition of the three components of the anti-corrosion filler.

[0057] Comparative Example 5 Unlike Example 1, this comparative example uses a single anti-corrosion filler, that is, all three components in the anti-corrosion filler are replaced with a single component, namely 17 parts of barium sulfate. The remaining process parameters are the same as in Example 1. This is used to demonstrate the effect of the combined addition of the three components of the anti-corrosion filler.

[0058] Comparative Example 6 Unlike Example 1, this comparative example sets the mass ratio of the three components in the anti-corrosion filler to 3:1:1, while keeping the other process parameters the same as in Example 1. This is to verify the necessity of the optimal ratio of the anti-corrosion filler.

[0059] Comparative Example 7 Unlike Example 1, this comparative example replaces coupling agent KH-560 with KH-550, while the remaining process parameters are the same as in Example 1.

[0060] Comparative Example 8 Unlike Example 1, this comparative example introduces nano-titanium dioxide into the composite system of the anti-corrosion filler, with a ratio of ultrafine zinc phosphate: mica iron oxide: barium sulfate: nano-titanium dioxide of 1:2:0.5:0.5. The remaining process parameters are the same as in Example 1.

[0061] Comparative Example 9 Unlike Example 1, this comparative example replaces the modified cycloaliphatic amine wet surface curing agent with a ketimine latent curing agent, while the remaining process parameters are the same as in Example 1.

[0062] Experimental Example 1 The anti-corrosion waxy colloidal coatings prepared in Examples 1-7 and Comparative Examples 1-9 were tested in a neutral salt spray test (3000 hours), a seawater alternating cycle test (2000 hours), and by the electrochemical low-frequency impedance modulus wet pull-off method for adhesion and water contact angle. The relevant results are summarized in Table 3.

[0063] (1) Neutral Salt Spray Test (3000 hours) Test Method: The edges of the carbon steel sample coated with 750μm paint were sealed, and a parallel scratch was made on the coating surface with a scriber, running through the sample to the substrate. The sample was then placed in a salt spray test chamber at a temperature of 35±2℃, and a 5% sodium chloride aqueous solution was used for continuous atomization spraying at a depth of 80cm. 2 The sedimentation rate in the collection area was 1-2 mL / h, and the pH of the solution was maintained in the range of 6.5-7.2. After a 3000-hour neutral salt spray test, the sample was taken out, rinsed with running water to remove surface salt, dried, and the corrosion resistance of the coating was immediately observed and evaluated. The coating was judged based on whether it showed continuous blistering, obvious rust, coating peeling, or decreased adhesion retention. Five samples were measured in parallel.

[0064] (2) Seawater alternating cycle test (2000 hours) Test method: The edges of the carbon steel sample coated with a 750μm thick layer of paint were sealed, and a parallel scratch was made on the coating surface, running through the sample to the substrate. The sample was then placed in a composite cyclic aging test chamber for a 2000-hour cycle of 7 days, involving the following factors: 3 consecutive days of alternating ultraviolet radiation and condensation, 3 consecutive days of neutral salt spray, and 1 day of placement in a -20℃ low-temperature freezer. After completion, the pull-off adhesion was tested, and the adhesion retention rate (%) was calculated. The formula for the adhesion retention rate is as follows: Adhesion retention rate (%) = (Pull-off adhesion of coating after cyclic treatment / Pull-off adhesion of coating before cyclic treatment) × 100% Five samples were measured in parallel and the average value was taken.

[0065] (3) Electrochemical low-frequency impedance modulus test method: The electrochemical low-frequency impedance modulus was tested according to GB / T 39482 / ISO16773. The specific test method is as follows: A three-electrode system was used to perform non-destructive electrochemical analysis on the coating sample. The cured coating sample was used as the working electrode (the exposed area was fixed at 16 cm²). 2 A saturated calomel electrode was used as the reference electrode, and a platinum mesh electrode was used as the auxiliary electrode. Both electrodes were immersed in an electrochemical cell containing a 3.5% sodium chloride solution simulating seawater. The system was connected to an electrochemical workstation. After the open-circuit potential stabilized, a sinusoidal perturbation voltage with an amplitude of 10 mV was applied, and the test frequency range was set to 10. 5 -10 -2 Hz, or 0.01Hz. By analyzing the AC impedance spectroscopy data obtained from the test, the impedance modulus at a frequency of 0.01Hz is read after a specified period of simulated seawater immersion, thus quantitatively characterizing the coating's barrier performance against electrolyte permeation. Five samples were measured in parallel, and the average value was taken.

[0066] (4) Wet pull-off adhesion test method: The wet pull-off adhesion test refers to GB / T 5210-2006 "Paints and Varnishes Pull-off Adhesion Test". The specific test method is as follows: Select a carbon steel structure test plate of an offshore platform, spray a continuous visible water film on the surface, and then apply the coating and cure the coating on the wet surface with the water film. During the test, use a special strong adhesive to vertically adhere a metal pull-off bar with a diameter of 20 mm to the surface of the cured coating. After the adhesive has completely cured, use a tool to cut through the coating around the circumference of the pull-off bar to the bottom of the substrate. Install it in an adhesion tester and apply a vertical pull force at a rate not exceeding 1 MPa / s until the coating is pulled off the substrate surface. Record the maximum load at the time of failure and calculate the wet pull-off adhesion (MPa) according to the formula. Take the average value of 5 parallel test samples.

[0067] (5) Water contact angle test method: The water contact angle test refers to ISO 19403-2:2024. The specific test method is as follows: A carbon steel sample coated with a 750μm thick coating is completely cured into a film at room temperature. In a constant temperature and humidity chamber at 23℃±2℃ and 50%±5% relative humidity, an optical contact angle measuring instrument is used. The titration method is adopted. A drop of deionized water is dropped on the coating surface through a micro-syringe. The static morphology of the water droplet on the coating surface is captured by a high-resolution CCD camera. The contact tangent between the droplet and the coating surface is automatically fitted by the matching image analysis software, thereby calculating the static water contact angle (°) under equilibrium state. In order to ensure the accuracy of the test results, five parallel tests are performed on different parts of the same coated carbon steel sample, and the average value is taken as the final test result.

[0068] (6) Curing time and recoating interval test methods: The curing time test is conducted according to the cotton ball blowing method and filter paper pressing method in GB / T 1728-2020 "Determination of Drying Time of Paint Film and Putty Film"; the maximum recoating interval test is conducted according to GB / T9271-2008. The specific method is as follows: In a windless standard curing room with a temperature of 20±1℃ and a relative humidity of 65%±5%, the paint is sprayed onto a carbon steel sample with a dry film thickness of 750μm.

[0069] The criteria for judging the surface drying time (cotton ball method): Drop a cotton ball freely onto the coating surface from a height of 10-15 mm, and gently blow on the cotton ball. When the cotton ball can be blown away and there is no degreased cotton fiber residue on the coating surface, the recorded time is the surface drying time. The experimental result was 3 hours.

[0070] The maximum recoating interval is determined as follows: After the first coat reaches surface dryness (3 hours), a second coat is applied at intervals of 0.2 hours, 0.5 hours, and 1 hour. After curing, the interlayer pull-off adhesion (referring to the wet pull-off adhesion test method) is measured. The microcrystalline wax has formed a dense hydrophobic wax phase structure on the surface of the first coat, resulting in a significant decrease in the interlayer adhesion of the second coat. However, when recoating within 3.5 hours, the epoxy crosslinking network of the first coat has not yet fully polymerized, and the microcrystalline wax has not completely sealed the pores, resulting in a higher level of interlayer adhesion retention. Therefore, the maximum recoating interval is determined to be 3.5 hours, meaning recoating must be completed within 0.5 hours after surface dryness.

[0071] Criteria for determining complete curing time (filter paper method): Place a qualitative filter paper on the coating surface, and place 200g of material with a bottom area of ​​1cm² on the filter paper. 2 The pressure block was placed for 30 seconds, and then the pressure block and filter paper were removed. The coating showed no filter paper residue and no stickiness, and the measured electrochemical impedance modulus reached a stable peak value ≥1×10⁻⁶. 9 Ω.cm 2 The recorded time is the fully solidified time.

[0072] It should be noted that surface drying time, recoating time, and complete curing time correspond to different stages in the coating formation process. Surface drying time mainly reflects the surface film formation rate, recoating time reflects the interlayer bonding requirements under continuous construction conditions, and complete curing time reflects the stable state after the cross-linked network is formed. Electrochemical impedance spectroscopy and corrosion resistance tests are used to evaluate the long-term protective capability of the cured coating in corrosive environments. Each indicator serves as the evaluation basis for its corresponding performance, and no single indicator can replace the evaluation of other performances.

[0073] Table 3 Performance test results of the anti-corrosion waxy colloidal coatings prepared in Examples 1-7 and Comparative Examples 1-9 As shown in Table 3, the anti-corrosion waxy colloidal coatings prepared in Examples 1-7 and Comparative Examples 1-9 of this invention exhibit significant differences in performance indicators, including neutral salt spray test (3000 hours), seawater alternating cycle test (2000 hours), electrochemical low-frequency impedance modulus, wet pull-off method adhesion, and water contact angle. Firstly, by comparing Example 1 with Comparative Example 1 (which did not undergo KH-560 surface modification), it is evident that the water contact angle of the KH-560-modified microcrystalline wax in Example 1 is as high as 115°, while that of the unmodified Comparative Example 1 is only 91.5°, and its performance deteriorates significantly in salt spray and alternating cycles. This indicates that the unmodified microcrystalline wax has poor compatibility with epoxy resin and cannot form stable hydrophobic microregions. KH-560 enables the microcrystalline wax to be uniformly dispersed in the system, thereby giving the coating high resistance to seawater wetting. A comparative analysis of Example 1 and Comparative Example 2, which uses ordinary E-51 bisphenol A epoxy resin, clearly shows that the wet pull-off adhesion of the coating using ordinary E-51 bisphenol A epoxy resin is only 7.8 MPa, far lower than that of Example 1. This indicates that the introduction of flexible siloxane segments effectively releases the internal stress during the curing of the anti-corrosion thick film and under alternating environments, significantly improving the anchoring strength and crack resistance of the coating on damp substrates. Finally, a comparison of Examples 1, 6, 7 and Comparative Examples 3-6 clearly shows that the electrochemical impedance modulus of Comparative Examples 3-5, which uses a single-component filler, is reduced to 10. 4 -10 5 The salt spray test failed, and the results of the extreme ratio test of the three components in Example 6 show that its physical barrier performance is far lower than that of Example 1; while the electrochemical impedance modulus of Example 1, with ultrafine zinc phosphate, mica iron oxide, and barium sulfate in a mass ratio of 1:2:1, is as high as 1.2 × 10⁻⁶. 9 Ω.cm 2 Furthermore, no bubbling occurred during 3000 hours of salt spray testing, indicating that a single-component anti-corrosion filler cannot meet the anti-corrosion requirements of the coating. The three components, through effective proportioning, can achieve effective barrier and anti-corrosion performance. Meanwhile, Experiments 6 and 7 also demonstrate that a ratio of 0.8-1.2:1.8-2.2:0.8-1.2 for the three components also exhibits good barrier and anti-corrosion performance.

[0074] In summary, this invention comprises a microcrystalline wax surface hydrophobic system constructed from a main epoxy resin and organosilicon compound, surface-modified with KH-560, a synergistic anti-corrosion system design of ultrafine zinc phosphate, mica iron oxide, and barium sulfate composites, and a wet-surface curing process, forming a complete anti-corrosion wax-based colloidal coating system. Experimental data show that the solvent-free two-component anti-corrosion wax-based colloidal coating prepared by this invention can achieve a balance between strong wet-surface adhesion and anti-corrosion performance. Under extremely complex corrosive conditions such as the splash zone of marine platforms, its good penetration resistance, extremely wet anchoring strength, and resistance to alternating aging fully meet the requirements of anti-corrosion engineering.

Claims

1. A corrosion-resistant waxy colloidal coating, characterized in that: The coating is a solvent-free two-component system, comprising: Component A and Component B. By weight, Component A comprises: 25-35 parts of microcrystalline wax modified with KH-560, 40-50 parts of silicone-based epoxy resin, 5-10 parts of hydrophobic reinforcing filler modified with HMDS, 1-3 parts of thixotropic agent, 10-20 parts of anti-corrosion filler, and 0.5-1.5 parts of anti-settling agent; Component B comprises: 90-98 parts of modified cycloaliphatic amine wet curing agent and 2-10 parts of curing accelerator; the silicone-based epoxy resin is prepared by modifying terminal epoxy group polydimethylsiloxane and E51 bisphenol A type epoxy resin at a mass ratio of 7-9:1-3; Component A and Component B are mixed at a mass ratio of 100:18-30.

2. The anti-corrosion waxy colloidal coating according to claim 1, characterized in that: The microcrystalline wax modified by KH-560 is made from No. 85 petroleum microcrystalline wax, which has a melting point of 80-90℃, an oil content of less than 0.5%, and a mass fraction of high isoparaffins and cycloparaffins greater than 70%.

3. The anti-corrosion waxy colloidal coating according to claim 1, characterized in that: The epoxy equivalent of the terminally epoxy group polydimethylsiloxane in the organosilicon compound epoxy resin is 550-650 g / eq; the epoxy value of the E51 bisphenol A type epoxy resin is 0.45-0.55 eq / 100g.

4. The anti-corrosion waxy colloidal coating according to claim 1, characterized in that: The hydrophobic reinforcing filler is hydrophobic fumed silica; the thixotropic agent is hydrophilic fumed silica; the modified alicyclic amine wet surface curing agent has an active hydrogen equivalent of 100-140 g / eq and an amine value of 300-350 mg KOH / g; and the curing accelerator is 2,4,6-tris(dimethylaminomethyl)phenol.

5. The anti-corrosion waxy colloidal coating according to claim 1, characterized in that: The anti-corrosion filler is composed of ultrafine zinc phosphate, mica iron oxide and barium sulfate; the mass ratio of ultrafine zinc phosphate, mica iron oxide and barium sulfate is 0.8-1.2:1.8-2.2:0.8-1.

2.

6. A corrosion-resistant waxy colloidal coating based on any one of claims 1-5 and its application method under wet conditions, characterized in that: The method is as follows: S1. Substrate Treatment: Surface treatment is performed on the area to be treated to remove surface contaminants, and the treatment level of the area to be treated reaches Sa2. The parameters were measured, including surface profile / roughness, soluble salts, dust, substrate temperature, ambient temperature and humidity, and dew point difference. S2. Mixing and curing the coating: Mechanically mix component A and component B at a mass ratio of 100:18-30, and allow to stand and cure at 20-30°C for 10-15 minutes; S3. Wet application: Application is carried out on the substrate surface when there is an adhering water film, a damp state, or a periodically water-exposed environment. The mixed coating is applied to the substrate surface by airless spraying, brushing, or roller coating. S4. Thick film formation: Control the wet film thickness to be 510-1050μm; The dry film thickness after curing at room temperature is 500-1000μm.

7. The anti-corrosion waxy colloidal coating and its application method under wet conditions according to claim 6, characterized in that: The anti-corrosion waxy colloidal coating, under substrate temperature of 15-25℃, has the following surface drying time: 2.5-3.5 hours; maximum recoating interval: 3-4 hours; and complete curing time to a usable state: 24-48 hours.

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