Curtain-coating thick-film resin anticorrosive paint and preparation method thereof

Abstract

The invention provides curtain-coating thick-film resin anticorrosive paint and a preparation method thereof, the resin anticorrosive paint is based on an epoxy / amine curing system, and three modules of polyvinylidene fluoride-nylon 6 friction power generation nanofibers, polyurea shell spiropyrane self-healing microcapsules and a microfluidic release channel are innovatively integrated. During preparation, low-shear dispersion-template construction of a microchannel-perfusion of a micropump and an inhibitor-ultraviolet / thermal dual-curing film forming is adopted. In service, the resin anticorrosive paint can be self-energized to collect vibration energy, an electric field promotes stress to trigger self-healing and accurately releases a corrosion inhibitor, a self-energized-self-healing-self-compensation closed loop is formed, and the impact resistance, crack resistance and corrosion resistance life of the thick-film resin anticorrosive paint are remarkably prolonged.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a thick-film resin anti-corrosion paint for spray coating and its preparation method. Background Technology

[0002] When metal components are used for extended periods in corrosive environments such as marine and chemical plants, the epoxy thick-film resin anti-corrosion paint on the surface suffers localized damage due to microcracks and defects. Corrosive media can easily penetrate the substrate through micropores, leading to protective failure and shortening the service life. To enhance the durability of resin anti-corrosion paint, self-healing technology uses polyurea-shell spiropyran self-healing microcapsules to release drugs or achieve reversible cross-linking to close cracks. However, this often relies on external excitation such as heat, light, or humidity, and the self-healing cycle and number of times are limited. Nano-triboelectric fibers can convert mechanical energy into electrical energy for cathodic protection, but it is difficult to efficiently couple with self-healing or drug release mechanisms. Microfluidic channel technology can precisely release inhibitors, but it lacks a continuous energy drive and is not easily stably constructed in high-viscosity thick-film systems.

[0003] Currently, no existing technology can organically integrate the three functions of self-powering, mechanically triggered self-healing, and microfluidic precise drug release in a thick-film epoxy coating system to form a truly active anti-corrosion closed-loop system. To address these shortcomings, this invention innovatively proposes a thick-film resin anti-corrosion paint that integrates triboelectric nanofibers, polyurea-shell spiropyran self-healing microcapsules, and microfluidic release channels. This enables self-powering, self-healing, and simultaneous targeted drug release during mechanical vibration or fluid erosion, constructing a "self-powering-self-healing-self-replenishment" intelligent protection system. Summary of the Invention

[0004] To address the problem of traditional thick-film resin anticorrosive paints failing due to microcracks, this invention proposes a coating-based thick-film resin anticorrosive paint and its preparation method. This resin anticorrosive paint constructs a self-energizing, self-healing, and self-repairing closed loop by dispersing polyvinylidene fluoride-nylon 6 triboelectric nanofibers, polyurea-spiropyran self-healing microcapsules, and water-soluble low-density polyethylene wax microspheres. This enables self-energizing of mechanical vibrations, rapid repair of micro-damage, and targeted release of inhibitors, significantly improving the corrosion resistance and service life of the thick-film resin anticorrosive paint.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A thick-film resin anti-corrosion paint for spray coating, wherein the resin anti-corrosion paint is prepared from the following raw materials in parts by weight: 100 parts of bisphenol A type epoxy resin, 50-60 parts of fatty amine curing agent, 1.0-2.0 parts of polyvinylidene fluoride-nylon 6 triboelectric nanofibers, 5-10 parts of polyurea-spiropyran self-healing microcapsules, 20-30 parts of water-soluble low-density polyethylene wax microspheres, 3-5 parts of water-soluble corrosion inhibitor, 0.5-1 part of defoamer, 0.5-1 part of leveling agent, and 1-2 parts of wetting and dispersing agent; Each component is uniformly dispersed in the epoxy resin / amine curing agent matrix.

[0006] Optionally, in the thick-film resin anti-corrosion paint, the polyvinylidene fluoride-nylon 6 triboelectric nanofibers have a diameter of 100-300 nm and an aspect ratio of 10-50.

[0007] Optionally, in the aforementioned thick-film resin anti-corrosion paint, the polyurea shell-spiropyran self-healing microcapsule shell is made of polyurea material with a shell thickness of 0.1-1.0 μm, and the core material is composed of spiropyran monomer and furan-2-yl methacrylate and N-phenylmaleimide monomer mixed in a mass ratio of 1:1-1:3.

[0008] Optionally, in the thick-film resin anticorrosive paint, the average particle size of the water-soluble low-density polyethylene wax microspheres is 20-80 μm.

[0009] Optionally, in the thick-film resin anti-corrosion paint, the water-soluble corrosion inhibitor is selected from one or more of sodium molybdate, sodium nitrite, sodium phosphate, and sodium metasilicate.

[0010] Optionally, in the thick-film resin anticorrosive paint, the defoamer is selected from one or more of siloxane defoamers, polyether defoamers, and polysiloxane-polyether copolymer defoamers, and the mass fraction is 0.1-0.2% of the total components.

[0011] Optionally, in the thick-film resin anti-corrosion paint, the leveling agent is one or more selected from polyether-modified siloxane, polyether-modified acrylate and polyfatty acid ester, and the mass fraction is 0.1-0.2% of the total components.

[0012] Optionally, in the thick-film resin anticorrosive paint for spray coating, the wetting and dispersing agent is one or more of sodium dodecylbenzene sulfonate, sodium stearate, sodium α-alkenyl sulfonate and lignin sulfonate, with a mass fraction of 0.2-0.4% of the total components.

[0013] Optionally, the preparation method of the thick-film resin anti-corrosion paint by spray coating includes the following steps: S1. Add bisphenol A type epoxy resin, fatty amine curing agent, defoamer, leveling agent and wetting and dispersing agent to a mixing container, and stir at 50-200 rpm for 5-15 min with low shear; S2. Add polyvinylidene fluoride-nylon 6 triboelectric nanofibers, polyurea chitosan pyran self-healing microcapsules and water-soluble low-density polyethylene wax microspheres in sequence, and continue to stir at 50-200 rpm for 10 min to ensure that each component is evenly dispersed and there are no agglomerates larger than 20 μm. S3. Apply the obtained wet paint to the substrate surface using a spray coating device, and expose it to ultraviolet light at an intensity of 10 mW / cm². 2 Pre-curing for 1-2 minutes; S4. Remove the water-soluble low-density polyethylene wax microspheres, then heat-cure at 80 ℃ for 1 h, and then heat-cure at 120 ℃ for another 2 h to obtain a thick film resin anti-corrosion paint with a dry film thickness of 200-500 μm.

[0014] The beneficial effects of this invention are: The resin anti-corrosion paint containing 1 wt% polyvinylidene fluoride-nylon 6 triboelectric nanofibers can sustainably output ≥0.05 mW / cm³ of electrical energy under 50 Hz vibration, without the need for external power to drive self-healing and drug release; the resin anti-corrosion paint containing 5 wt% polyurea-shell spiropyran self-healing microcapsules has a crack recovery rate of ≥90% within 3 min under 500 kPa stress; after removing 20 μm diameter water-soluble low-density polyethylene wax microspheres, microchannels are formed, which can quantitatively release inhibitors to achieve local chemical protection; the dry film thickness is 200 μm-500 μm, the adhesion is grade 5, the impact strength is increased by 20%, and the lifespan is extended by 2 times after 2000 h of salt spray test; the nanomaterial refinement structure increases the density by 30%, significantly enhancing the corrosion resistance lifespan and maintenance cycle of metal components. Attached Figure Description

[0015] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0016] Figure 1 This is a bar chart comparing the self-powered output power density and strength recovery rate of various samples in this invention; Figure 2 This is a bar chart comparing the single inhibitor release amount and local salt spray protection area of ​​each sample in this invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0018] Example 1: This embodiment 1 describes a thick-film resin anti-corrosion paint, which is prepared from the following raw materials in parts by weight: 100 parts of bisphenol A epoxy resin, 55 parts of fatty amine curing agent, 1.0 part of polyvinylidene fluoride-nylon 6 triboelectric nanofiber, 7 parts of polyurea-spiropyran self-healing microcapsules, 25 parts of water-soluble low-density polyethylene wax microspheres, 4 parts of water-soluble corrosion inhibitor, 0.8 parts of defoamer, 0.8 parts of leveling agent, and 1.5 parts of wetting and dispersing agent; The preparation method of polyvinylidene fluoride-nylon 6 triboelectric nanofibers is as follows: S1. Dissolve polyvinylidene fluoride (PVDF) and nylon 6 in a dimethylformamide / acetone mixed solvent with a volume ratio of 7:3 at a mass ratio of 8:2 to prepare a 10 wt% spinning solution. Stir at room temperature for 2 h until completely dissolved. S2. The obtained solution is drawn into a syringe with a needle. The voltage is set to 15 kV, the injection flow rate to 0.5 mL / h, and the distance between the needle and the receiving plate to 15 cm. The receiving plate is rotated at 200 rpm to collect the fibers. S3. After drying at room temperature for 24 h, polyvinylidene fluoride-nylon 6 triboelectric nanofibers with a diameter of 200 nm and an aspect ratio of 30 are obtained, which can be directly dispersed in an epoxy resin / amine curing agent matrix.

[0019] The preparation method of polyurea-chitospiran self-healing microcapsules is as follows: S1. Dissolve a mixture of spiropyran, furan-2-yl methacrylate, and N-phenylmaleimide in toluene at a mass ratio of 1:2 to obtain a 10 wt% oil phase solution; S2. Dissolve sodium dodecyl sulfate with a mass fraction of 2‰ in deionized water and stir thoroughly to form a homogeneous emulsion aqueous solution; S3. Stir the solution obtained in S2 at a speed of 750 rpm, and add the oil phase solution dropwise into it within 10 min, and continue stirring for another 30 min to form an emulsion; S4. Dissolve hexamethylenediamine in propylene glycol to prepare a 10 wt% hexamethylenediamine-propylene glycol solution. Stir continuously at 750 rpm while slowly adding the hexamethylenediamine-propylene glycol solution dropwise. After the addition is complete, continue stirring for 2 hours to complete the in-situ polymerization of the polyurea shell at the oil / water interface. S5. After the reaction is complete, the polyurea chitospira pyran self-healing microcapsule emulsion is centrifuged at 3000 rpm for 10 min, washed repeatedly with deionized water 3 times, and finally dried in a vacuum drying oven at 50 ℃ for 12 h to obtain polyurea chitospira pyran self-healing microcapsules with an average shell thickness of about 0.2 μm and a particle size of about 5 μm-10 μm.

[0020] The preparation method of water-soluble low-density polyethylene wax microspheres is as follows: S1. Add 5 wt% low-density polyethylene wax to hot water at 80 ℃, and ultrasonically emulsify for 10 min under magnetic stirring at 500 rpm to form a homogeneous wax emulsion. S2. After the emulsion has cooled to room temperature, add 0.5 wt% sodium carboxymethyl cellulose and stir at 300 rpm for 5 min to stabilize the emulsion droplets. S3. Water-soluble low-density polyethylene wax microspheres were separated by stirring at 3000 rpm for 10 min. The microspheres were washed twice with deionized water and dried under vacuum at 50 ℃ for 4 h to obtain water-soluble low-density polyethylene wax microspheres with an average particle size of 35 μm.

[0021] This embodiment describes a method for preparing a thick-film resin anti-corrosion paint, the specific preparation steps of which are as follows: S1. Add bisphenol A type epoxy resin, fatty amine curing agent, defoamer, leveling agent and wetting and dispersing agent to a mixing container and stir at 100 rpm for 10 min with low shear. S2. Add polyvinylidene fluoride-nylon 6 triboelectric nanofibers, polyurea chitosan pyran self-healing microcapsules and water-soluble low-density polyethylene wax microspheres in sequence, and continue stirring at 100 rpm for 10 min. S3. Apply the obtained wet paint to the substrate surface using a spray coating device, and expose it to ultraviolet light at an intensity of 10 mW / cm². 2 Pre-curing for 1.5 min; S4. Remove the water-soluble low-density polyethylene wax microspheres, then heat-cure at 80 ℃ for 1 h, and then heat-cure at 120 ℃ for another 2 h to obtain a thick film resin anti-corrosion paint with a dry film thickness of 300 μm.

[0022] Example 2: The thick-film resin anti-corrosion paint for spraying in this embodiment 2 is prepared from the following raw materials in parts by weight: 100 parts of bisphenol A epoxy resin, 55 parts of fatty amine curing agent, 1.0 part of polyvinylidene fluoride-nylon 6 triboelectric nanofiber, 5 parts of polyurea-spiropyran self-healing microcapsules, 25 parts of water-soluble low-density polyethylene wax microspheres, 4 parts of water-soluble corrosion inhibitor, 0.8 parts of defoamer, 0.8 parts of leveling agent, and 1.5 parts of wetting and dispersing agent; The preparation methods of polyvinylidene fluoride-nylon 6 triboelectric nanofibers, polyurea chitosan pyran self-healing microcapsules and water-soluble low-density polyethylene wax microspheres in Example 2 are the same as those in Example 1; The preparation method of the thick film resin anticorrosive paint in Example 2 is the same as that in Example 1.

[0023] Example 3: The thick-film resin anti-corrosion paint for spraying in this embodiment 3 is prepared from the following raw materials in parts by weight: 100 parts of bisphenol A epoxy resin, 55 parts of fatty amine curing agent, 2.0 parts of polyvinylidene fluoride-nylon 6 triboelectric nanofibers, 7 parts of polyurea-spiropyran self-healing microcapsules, 25 parts of water-soluble low-density polyethylene wax microspheres, 4 parts of water-soluble corrosion inhibitor, 0.8 parts of defoamer, 0.8 parts of leveling agent, and 1.5 parts of wetting and dispersing agent; The preparation methods of polyvinylidene fluoride-nylon 6 triboelectric nanofibers, polyurea-shell spiropyran self-healing microcapsules and water-soluble low-density polyethylene wax microspheres in Example 3 are the same as those in Example 1; The preparation method of the thick film resin anticorrosive paint in Example 3 is the same as that in Example 1.

[0024] Comparative Example 1: To investigate the effect of polyurea-shell pyran self-healing microcapsules on the performance of resin anticorrosive paint, a thick-film resin anticorrosive paint for coating in Comparative Example 1 was prepared from the following raw materials in parts by weight: 100 parts of bisphenol A epoxy resin, 55 parts of fatty amine curing agent, 1.0 part of polyvinylidene fluoride-nylon 6 triboelectric nanofiber, 0 parts of polyurea-spiropyran self-healing microcapsules, 25 parts of water-soluble low-density polyethylene wax microspheres, 4 parts of water-soluble corrosion inhibitor, 0.8 parts of defoamer, 0.8 parts of leveling agent, and 1.5 parts of wetting and dispersing agent; The preparation methods of polyvinylidene fluoride-nylon 6 triboelectric nanofibers, polyurea chitosan pyran self-healing microcapsules and water-soluble low-density polyethylene wax microspheres in Comparative Example 1 are the same as those in Example 1. The preparation method of the thick film resin anticorrosive paint in Comparative Example 1 is the same as that in Example 1.

[0025] Comparative Example 2: To investigate the effect of polyvinylidene fluoride-nylon 6 triboelectric nanofibers on the performance of resin anticorrosive paint, a thick-film resin anticorrosive paint for comparative example 2 was prepared from the following raw materials in parts by weight: 100 parts of bisphenol A epoxy resin, 55 parts of fatty amine curing agent, 0 parts of polyvinylidene fluoride-nylon 6 triboelectric nanofibers, 7 parts of polyurea-shell spiropyran self-healing microcapsules, 25 parts of water-soluble low-density polyethylene wax microspheres, 4 parts of water-soluble corrosion inhibitor, 0.8 parts of defoamer, 0.8 parts of leveling agent, and 1.5 parts of wetting and dispersing agent; The preparation methods of polyvinylidene fluoride-nylon 6 triboelectric nanofibers, polyurea chitosan pyran self-healing microcapsules and water-soluble low-density polyethylene wax microspheres in Comparative Example 2 are the same as those in Example 1. The preparation method of the thick film resin anticorrosive paint in Comparative Example 2 is the same as that in Example 1.

[0026] 1. Self-powered output test The prepared resin anticorrosive paint sample was cut into 30 mm × 30 mm pieces, and aluminum foil was attached to the back as an electrode before curing. The sample was fixed on a vibration table, and the vibration frequency was set to 50 Hz and the amplitude to 0.5 mm. The horizontal amplitude of the vibration table was preferably in sinusoidal mode. The upper and lower electrodes of the sample were connected to a voltage-current meter with wires, and the instantaneous voltage and current data were recorded within 10 minutes of continuous vibration. The output voltage and current were taken as the steady-state average value as the self-powered output of the resin anticorrosive paint (mW / cm). 3 The formula for calculating instantaneous power density is: ;

[0027] Where V(t) and I(t) are the output voltage and current, respectively, and A is the sample area.

[0028] Table 1 Comparison of self-powered output power density of each sample ; In Example 3, when the fiber content was increased to 2.0 wt%, the output power density was 0.09 mW / cm³, which was 50% higher than that of 1.0 wt%, verifying that the amount of fiber significantly enhanced the self-powering capability.

[0029] 2. Mechanically Triggered Self-Healing Efficiency Test The cured resin anticorrosive paint sample was cut into 50 mm × 10 mm strips and adhered to a rigid metal substrate. An initial crack was made along the length direction at the center with a sharp blade, with a depth of about 50 μm and a length of about 5 mm. The cracked sample was placed in a fixture that could apply normal pressure, and the load was increased to 500 kPa by a screw and held for 3 min. After the pressure was removed, the crack width change was measured under the same field of view using a digital microscope to calculate the closure rate. Subsequently, the sample was stretched to fracture at a rate of 5 mm / min on a universal tensile testing machine. The fracture strength was recorded and compared with the unscratched control sample to calculate the strength recovery rate.

[0030] Table 2 Comparison of Mechanically Triggered Self-Healing Efficiency of Various Samples ; Examples 1 and 3 showed a closure rate of >90%, while the comparative example of polyurea-free chitospiropyran self-healing microcapsules showed a closure rate of only 5%, indicating that the organic chemical capsule is the decisive factor in the self-healing function.

[0031] 3. Corrosion inhibitor release and local protection test The resin anticorrosive paint sample, after curing and removal of water-soluble low-density polyethylene wax microspheres, was cut into 20 cm pieces. 2For a 4 cm × 5 cm area segment, 10 μL of a simulated inhibitor solution containing 0.1 wt% UV dye was injected into the microchannel inlet using a syringe. After standing for 1 min, the effluent was collected at the microchannel outlet, and the dye concentration was measured at 420 nm using a UV-vis spectrophotometer. The mass of a single release was calculated based on the channel area. Subsequently, 10 μL of 3 wt% NaCl solution was added to the cracks on the surface of the resin anticorrosive paint. After standing at room temperature for 24 h, the trace diffusion area was measured using an optical microscope and image analysis software to evaluate the local chemical protection effect.

[0032] Table 3 Comparison of Simulated Inhibitor Single Release Amount and Local Salt Spray Protection Area for Each Sample ; Examples 1-3 show a single drug release dose of approximately 0.02 g / cm³. 2 Salt traces < 5 mm², comparative zero release accompanied by > 20 mm² 2 The diffusion effect highlights the local protective advantages of microchannel quantitative drug delivery.

[0033] 4. Salt spray corrosion resistance test Cured resin anticorrosive paint samples were prepared on aluminum alloy plates measuring 50 mm × 100 mm, with the resin anticorrosive paint thickness controlled at 300 μm. Following ASTM B117 standards, the samples were placed in a salt spray test chamber and continuously exposed to a 5 wt% NaCl mist solution with pH 6.5-7.2 at 35°C for 2000 h. Samples were removed every 500 h, and the rust level and peeling area were recorded using a 5× magnifying glass and a digital camera. The peeling area was quantified using image analysis software to evaluate the long-term protective performance of the closed-loop system.

[0034] Table 4. Comparison of Salt Spray Corrosion Resistance of Samples under Different Exposure Times

[0035] After 2000 hours of salt spray testing, Example 3 showed only Grade 1 corrosion with a peeling thickness of <2 mm. 2 Comparative peeling >25 mm 2 This demonstrates that the closed-loop system significantly extends the corrosion resistance life of the resin anti-corrosion paint.

[0036] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A thick-film resin anti-corrosion paint for spray coating, characterized in that, The ingredients comprise the following parts by weight: 100 parts of bisphenol A type epoxy resin, 50-60 parts of fatty amine curing agent, 1.0-2.0 parts of polyvinylidene fluoride-nylon 6 triboelectric nanofibers, 5-10 parts of polyurea-spiropyran self-healing microcapsules, 20-30 parts of water-soluble low-density polyethylene wax microspheres, 3-5 parts of water-soluble corrosion inhibitor, 0.5-1 part of defoamer, 0.5-1 part of leveling agent, and 1-2 parts of wetting and dispersing agent; Each component is uniformly dispersed in the epoxy resin / amine curing agent matrix.

2. The thick-film resin anti-corrosion paint according to claim 1, characterized in that, The polyvinylidene fluoride-nylon 6 triboelectric nanofibers have a diameter of 100-300 nm and an aspect ratio of 10-50.

3. The thick-film resin anti-corrosion paint according to claim 1, characterized in that, The polyurea-spiropyran self-healing microcapsule shell is made of polyurea material with a shell thickness of 0.1-1.0 μm. The core material is composed of spiropyran monomer and furan-2-yl methacrylate and N-phenylmaleimide monomer mixed in a mass ratio of 1:1-1:

3.

4. The thick-film resin anti-corrosion paint according to claim 1, characterized in that, The average particle size of the water-soluble low-density polyethylene wax microspheres is 20-80 μm.

5. The thick-film resin anti-corrosion paint according to claim 1, characterized in that, The water-soluble corrosion inhibitor is selected from one or more of sodium molybdate, sodium nitrite, sodium phosphate, and sodium metasilicate.

6. The thick-film resin anti-corrosion paint according to claim 1, characterized in that, The defoamer is selected from one or more of siloxane defoamers, polyether defoamers, and polysiloxane-polyether copolymer defoamers, and its mass fraction is 0.1-0.2% of the total components.

7. The thick-film resin anti-corrosion paint according to claim 1, characterized in that, The leveling agent is selected from one or more of polyether-modified siloxanes, polyether-modified acrylates and polyfatty acid esters, with a mass fraction of 0.1-0.2% of the total components.

8. The thick-film resin anti-corrosion paint according to claim 1, characterized in that, The wetting and dispersing agent is one or more of sodium dodecylbenzenesulfonate, sodium stearate, sodium α-alkenylsulfonate and lignin sulfonate, with a mass fraction of 0.2-0.4% of the total components.

9. A method for preparing a thick-film resin anti-corrosion paint by spraying, wherein the resin anti-corrosion paint is as described in any one of claims 1-8, characterized in that, The steps are as follows: S1. Add bisphenol A type epoxy resin, fatty amine curing agent, defoamer, leveling agent and wetting and dispersing agent to a mixing container, and stir at 50-200 rpm for 5-15 min with low shear; S2. Add polyvinylidene fluoride-nylon 6 triboelectric nanofibers, polyurea chitosan pyran self-healing microcapsules and water-soluble low-density polyethylene wax microspheres in sequence, and continue stirring at 50-200 rpm for 10 min. S3. Apply the obtained wet paint to the substrate surface using a spray coating device, and expose it to ultraviolet light at an intensity of 10 mW / cm². 2 Pre-curing for 1-2 minutes; S4. Remove the water-soluble low-density polyethylene wax microspheres, then heat-cure at 80 ℃ for 1 h, and then heat-cure at 120 ℃ for another 2 h to obtain a thick film resin anti-corrosion paint with a dry film thickness of 200-500 μm.

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