High-adhesion acrylic coating and preparation method thereof

Abstract

The invention belongs to the technical field of coatings, and particularly discloses a high-adhesion acrylic coating and a preparation method thereof.In the presence of dopamine hydrochloride, nano-silica is subjected to microwave radiation to obtain modified nano-silica; then mixing the mixture with an acrylic resin emulsion; adding an isocyanate curing agent, a titanium dioxide pigment, hydroxyl-terminated hyperbranched polyester, a polycarboxylic acid ammonium salt dispersing agent, a polysiloxane defoaming agent and magnesium lithium silicate by adopting a continuous flow process; the paint with good adhesive force, corrosion resistance, impedance and low surface roughness is prepared through segmented curing, and the application prospect is wide.

Description

Technical Field

[0001] The present invention belongs to the technical field of coatings, and specifically discloses a high-adhesion acrylic coating and a preparation method thereof. Background Art

[0002] Due to its excellent weather resistance, chemical resistance and decoration, acrylic coatings are widely used in fields such as construction, automotive, and marine engineering. However, with the diversification of application scenarios and the improvement of performance requirements, traditional acrylic coatings gradually expose some deficiencies in adhesion, corrosion resistance, etc. The adhesion of traditional acrylic coatings on metal or non-metal substrates is limited. Especially in harsh environments such as high humidity and high salt spray, peeling or falling off is likely to occur, resulting in a decline in the durability and protective performance of the coating; the corrosion resistance in the marine environment is poor, and the coating is easily penetrated by corrosive media, restricting its application in key components such as marine engineering equipment; the traditional preparation process is difficult to achieve uniform dispersion of nano-fillers, resulting in a relatively high surface roughness of the coating and insufficient denseness, affecting the mechanical properties and protective performance of the coating; the traditional curing process has low efficiency, high energy consumption, and is prone to generating internal stress in the coating, affecting the adhesion and durability of the coating; in addition, the functionality of traditional acrylic coatings is mainly achieved by adding single-functional fillers, which is difficult to meet the requirements of multi-scenario applications. Summary of the Invention

[0003] To solve the above-mentioned problems of the prior art, in the presence of dopamine hydrochloride, the present invention irradiates nano-silica with microwave to obtain modified nano-silica, and combines the continuous flow process and the dual-wavelength photocuring technology to mix it with acrylic resin emulsion, isocyanate curing agent, titanium dioxide pigment, hydroxyl-terminated hyperbranched polyester, ammonium polycarboxylate dispersant, polysiloxane defoamer, and lithium magnesium silicate to obtain an acrylic coating with characteristics such as high adhesion, corrosion resistance, impedance, and relatively low surface roughness.

[0004] To achieve the above object, the present invention adopts the following technical solutions to solve the technical problems:

[0005] In a first aspect, the present invention provides a high-adhesion acrylic coating, which comprises 45-55 parts by weight of acrylic resin emulsion, 10-12 parts of curing agent, 15-18 parts of pigment, 6-8 parts of modified nano-silica, 3-5 parts of hydroxyl-terminated hyperbranched polyester, 2-3 parts of dispersant, 0.8-1.2 parts of defoamer, and 1.5-2.5 parts of lithium magnesium silicate;

[0006] Among them, the modified nano-silica is polydopamine / nano-silica composite particles.

[0007] Through the synergistic effect of polydopamine / nanosilica composite particles and hydroxyl-terminated hyperbranched polyester, a bionic multi-level micro-nano interface structure is constructed, which improves the coating adhesion by more than 40% (compared with traditional acrylic coatings), and at the same time realizes defect-free curing of a 150-200 μm thick coating.

[0008] In some embodiments, by weight, it includes 50 parts of acrylic resin emulsion, 11 parts of curing agent, 16 parts of pigment, 7 parts of modified nanosilica, 4 parts of hydroxyl-terminated hyperbranched polyester, 2.5 parts of dispersant, 1 part of defoamer, and 2 parts of lithium silicate magnesium.

[0009] In some embodiments, the curing agent is an isocyanate curing agent; the pigment is titanium dioxide; the dispersant is an ammonium polycarboxylate dispersant; the defoamer is a polysiloxane defoamer.

[0010] In some embodiments, the preparation of the modified nanosilica includes the following steps:

[0011] S1. Disperse the nanosilica in a Tris buffer solution with pH = 8-9, and add dopamine hydrochloride to a concentration of 1.5-2.5 mg / mL;

[0012] S2. Apply intermittent microwave radiation at 40-50 °C with 80-120 W for 6-10 h;

[0013] S3. After centrifugal separation and washing with an ethanol / water mixed solvent, vacuum freeze-drying is carried out to obtain composite particles with a polydopamine coating layer thickness of 5-20 nm.

[0014] By using the microwave intermittent radiation process, the thickness of the polydopamine coating layer can be precisely controlled (5-20 nm), the coating uniformity is improved by 65% compared with the traditional water bath method, and the dispersion particle size of the nanoparticles in the resin is reduced from the conventional >1 μm to ≤0.5 μm.

[0015] In a second aspect, the present invention also provides a method for preparing the above high-adhesion acrylic coating, including the following steps:

[0016] (1) Premix the acrylic resin emulsion and the modified nanosilica through a microchannel reactor;

[0017] (2) Under nitrogen protection, sequentially add the curing agent, pigment and other additives by using a continuous flow process;

[0018] (3) Cure in segments by dual-wavelength ultraviolet-LED: irradiance energy of 600-1000 mJ / cm at 365 nm 2 followed by irradiance energy of 300-500 mJ / cm at 405 nm 2; The 365nm and 405nm segmented curing increases the light penetration depth to 0.8mm, and the cross-linking density of the bottom layer is increased by 22%, solving the adhesion gradient problem caused by uneven curing of thick coatings.

[0019] (4) Three-stage dispersion by a high-pressure homogenizer to a medium particle size ≤ 0.5μm.

[0020] In some embodiments, in step (1), the flow rate ratio of the acrylic resin emulsion to the modified nano-silica is (4-6):1.

[0021] In some embodiments, in step (1), the microchannel reactor adopts a 3D printed dendritic fractal structure, with a mixing efficiency ≥ 98% and a single-channel length ≤ 5cm. Using a 3D printed dendritic fractal reactor, the mixing efficiency is increased to 98%, and the single-channel length ≤ 5cm avoids local overheating, reducing the energy consumption by 35% compared to traditional T-shaped mixers and reducing the nanoparticle aggregates by 80%. Preferably, use the Advanced-Flow TM Reactor G4 type (Corning AFR G4) microchannel reactor.

[0022] Specifically, the coating prepared by the above preparation method needs to meet:

[0023] I. The surface roughness Ra measured by atomic force microscopy ≤ 10nm;

[0024] II. The low-frequency impedance modulus value measured by electrochemical impedance spectroscopy in 3.5% NaCl solution ≥ 1×10^8 Ω·cm 2 .

[0025] The Ra ≤ 10nm ultra-smooth surface reduces the corrosion sites by 85%, and the 8 Ω·cm 2 impedance modulus value is increased by three orders of magnitude compared to the conventional coating, meeting the IEC 60529-IP68 protection standard for marine engineering equipment.

[0026] In the third aspect, the present invention also provides the application of the above coating in marine engineering equipment, specifically for: the corrosion-resistant coating of the seawater valve of a titanium alloy submarine, with a coating thickness of 150-200μm and no rust after 3000h of salt spray test.

[0027] In the fourth aspect, the present invention also provides the application of the above coating in automotive lightweighting, specifically for: the primer coating of a carbon fiber composite body part, with an adhesion reaching grade 5B of ASTM D3359 standard.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] In the presence of dopamine hydrochloride, nano-silica is subjected to microwave radiation to obtain modified nano-silica, which is then mixed with an acrylic resin emulsion, and an isocyanate curing agent, titanium dioxide pigment, hydroxyl-terminated hyperbranched polyester, ammonium polycarboxylate dispersant, polysiloxane defoamer, and lithium magnesium silicate are added, and a coating is prepared by segmented curing. Compared with traditional acrylic coatings, the prepared coating has good adhesion, corrosion resistance, impedance, and lower surface roughness, and has broad application prospects. Detailed implementation manners

[0030] The following describes the technical solutions in the embodiments of the present invention clearly and completely in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0031] In the present invention, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are considered continuous and include the minimum and maximum values of the range, as well as each value between such minimum and maximum values. Further, when the range refers to an integer, each integer between the minimum and maximum values of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0032] In the present invention, there is no particular limitation on the specific dispersion and stirring treatment methods.

[0033] In the present invention, the test methods used are all conventional methods unless otherwise specified; the materials, reagents, etc. used are reagents and materials that can be obtained from commercial channels unless otherwise specified.

[0034] The raw materials used in the present invention are shown in Table 1 below.

[0035] Table 1 Raw material source table

[0036]

[0037]

[0038] Example 1

[0039] A high-adhesion acrylic coating, the preparation method of which specifically includes:

[0040] 1. By Advanced-Flow TMThe Reactor G4 microchannel reactor premixes 45 g of acrylic resin emulsion with 6 g of modified nano-silica, and the flow rate ratio is 4:1.

[0041] 2. Under nitrogen protection, 10 g of isocyanate curing agent, 15 g of titanium dioxide pigment, 3 g of hydroxyl-terminated hyperbranched polyester, 2 g of ammonium polycarboxylate dispersant, 0.8 g of polysiloxane defoamer, and 1.5 g of lithium magnesium silicate are sequentially added using a continuous flow process.

[0042] 3. Cure in segments with dual-wavelength ultraviolet-LED: irradiate at 365 nm, the irradiation energy is 600 mJ / cm 2 , the irradiation time is 5 min; then irradiate at 405 nm, the irradiation energy is 300 mJ / cm 2 , the irradiation time is 3 min.

[0043] 4. Disperse to a medium particle size of ≤0.5 μm in three stages using a high-pressure homogenizer.

[0044] In this example, the preparation of the modified nano-silica includes:

[0045] (1) Disperse 8 g of nano-silica in 1 L of Tris buffer solution with pH = 8, and add dopamine hydrochloride to a concentration of 1.5 mg / mL.

[0046] (2) Apply 80 W of microwave intermittent radiation at 40 °C for 10 h (microwave radiation for 4 min, intermittent for 3 min).

[0047] (3) Centrifugation separation parameters: rotation speed 8000 r / min, centrifugation time 15 min. After washing 3 times with an ethanol / water mixed solvent (volume ratio of ethanol to water is 1:1), vacuum freeze-dry to obtain composite particles with a polydopamine coating layer thickness of 5 - 10 nm.

[0048] Example 2

[0049] A high-adhesion acrylic paint, and its preparation method specifically includes:

[0050] 1. Through Advanced-Flow TM The Reactor G4 microchannel reactor premixes 50 g of acrylic resin emulsion with 7 g of modified nano-silica, and the flow rate ratio is 5:1.

[0051] 2. Under nitrogen protection, 11 g of isocyanate curing agent, 16 g of titanium dioxide pigment, 4 g of hydroxyl-terminated hyperbranched polyester, 2.5 g of ammonium polycarboxylate dispersant, 1 g of polysiloxane defoamer, and 2 g of lithium magnesium silicate are sequentially added using a continuous flow process.

[0052] 3. Cured in segments by dual-wavelength ultraviolet-LED: irradiated at 365 nm with an irradiation energy of 800 mJ / cm 2 , irradiation time of 4 min; then irradiated at 405 nm with an irradiation energy of 400 mJ / cm 2 , irradiation time of 2.5 min.

[0053] 4. Dispersed to a medium particle size of ≤0.5 μm in three stages using a high-pressure homogenizer.

[0054] In this example, the preparation of the modified nano-silica includes:

[0055] (1) Disperse 10 g of nano-silica in 1 L of Tris buffer solution with a pH of 8.5, and add dopamine hydrochloride to a concentration of 2 mg / mL.

[0056] (2) Apply 100 W of microwave intermittent radiation at 45 °C for 8 h (microwave radiation for 5 min, intermittent for 2 min).

[0057] (3) Centrifugation separation parameters: rotation speed of 10000 r / min, centrifugation time of 12 min. After washing 3 times with an ethanol / water mixed solvent (volume ratio of ethanol to water is 1:1), vacuum freeze-dry to obtain composite particles with a polydopamine coating layer thickness of 10 - 15 nm.

[0058] Example 3

[0059] A high-adhesion acrylic paint, the preparation method of which specifically includes:

[0060] 1. Through Advanced-Flow TM Reactor G4 type microchannel reactor premixes 55 g of acrylic resin emulsion and 8 g of modified nano-silica with a flow rate ratio of 6:1.

[0061] 2. Under nitrogen protection, sequentially add 12 g of isocyanate curing agent, 18 g of titanium dioxide pigment, 5 g of hydroxyl-terminated hyperbranched polyester, 3 g of polycarboxylate ammonium salt dispersant, 1.2 g of polysiloxane defoamer, and 2.5 g of lithium magnesium silicate using a continuous flow process.

[0062] 3. Cured in segments by dual-wavelength ultraviolet-LED: irradiated at 365 nm with an irradiation energy of 1000 mJ / cm 2 , irradiation time of 3 min; then irradiated at 405 nm with an irradiation energy of 500 mJ / cm 2 , irradiation time of 2 min.

[0063] 4. Dispersed to a medium particle size of ≤0.5 μm in three stages using a high-pressure homogenizer.

[0064] In this embodiment, the preparation of the modified nano-silica includes:

[0065] (1) Disperse 12 g of nano-silica in 1 L of Tris buffer solution with pH = 9, and add dopamine hydrochloride to a concentration of 2.5 mg / mL.

[0066] (2) Apply intermittent microwave radiation at 120 W for 6 h at 50 °C (microwave radiation for 6 min, intermittent for 1 min).

[0067] (3) Centrifugation separation parameters: rotation speed 12000 r / min, centrifugation time 10 min. After washing 3 times with an ethanol / water mixed solvent (volume ratio of ethanol to water is 1:1), vacuum freeze-drying is carried out to obtain composite particles with a poly-dopamine coating layer thickness of 15 - 20 nm.

[0068] Comparative Example 1

[0069] The difference between Comparative Example 1 and Example 2 is that Comparative Example 1 does not add modified nano-silica and has a different curing process, while others are the same.

[0070] Prepare an acrylic coating by a traditional method without adding modified nano-silica. Use an ordinary T-shaped mixer for raw material mixing. The curing process is a single 365 nm ultraviolet irradiation with an irradiation energy of 1400 mJ / cm 2 , and the irradiation time is 8 min.

[0071] Comparative Example 2

[0072] The difference between Comparative Example 2 and Example 2 is that Comparative Example 2 uses an equal amount of nano-silica to replace the modified nano-silica and has a different curing process, while others are the same.

[0073] Add unmodified nano-silica (directly use commercially available nano-silica). Use an ordinary T-shaped mixer for raw material mixing. The curing process is a single 365 nm ultraviolet irradiation with an irradiation energy of 1400 mJ / cm 2 , and the irradiation time is 8 min.

[0074] Comparative Example 3

[0075] The difference between Comparative Example 3 and Example 2 is that Comparative Example 3 uses an equal amount of ordinary aliphatic polyester polyol (molecular weight of 2000) to replace the hydroxyl-terminated hyperbranched polyester, while others are the same.

[0076] Comparative Example 4

[0077] The difference between Comparative Example 4 and Example 2 is that Comparative Example 4 uses an equal amount of sodium dodecylbenzenesulfonate to replace the polycarboxylate ammonium salt dispersant, while others are the same.

[0078] Comparative Example 5

[0079] The difference between Comparative Example 5 and Example 2 lies in the curing process, while others are the same.

[0080] Single 405nm ultraviolet irradiation was used for curing, with an irradiation energy of 1500mJ / cm 2 , and the irradiation time was 10 min.

[0081] Test Example 1

[0082] The coatings prepared in Examples 1-3 and Comparative Examples 1-5 were respectively subjected to adhesion, corrosion resistance, surface roughness, impedance and antibacterial tests.

[0083] I. Adhesion test

[0084] Experimental standard: The adhesion test was carried out according to ASTM D3359 standard.

[0085] Experimental steps:

[0086] (1) The coatings prepared in Examples 1-3 and Comparative Examples 1-5 were respectively coated on the pretreated titanium alloy substrates to form a coating with a thickness of about 150μm.

[0087] (2) The coatings were cured for 7 days in a standard environment (temperature 23±2°C, relative humidity 50±5%).

[0088] (3) Six parallel incisions were made on the coating with a tool, the incision spacing was 1mm, and the depth reached the substrate.

[0089] (4) A pressure-sensitive tape was pasted on the incision area and then quickly torn off.

[0090] (5) Observe the peeling situation of the coating from the substrate and rate it according to ASTM D3359 standard.

[0091] II. Corrosion resistance test

[0092] Experimental standard: The salt spray test was carried out according to GB / T 1771-2007 standard.

[0093] Experimental steps:

[0094] (1) The coatings prepared in Examples 1-3 and Comparative Examples 1-5 were respectively coated on the pretreated titanium alloy substrates to form a coating with a thickness of about 150μm.

[0095] (2) The coatings were cured for 7 days in a standard environment (temperature 23±2°C, relative humidity 50±5%).

[0096] (3) Place the coated specimens in a salt spray test chamber. The test solution is a 5% sodium chloride solution, the test temperature is 35 ± 2 °C, and the salt spray deposition rate is 1 - 2 mL / (h·80 cm 2 ).

[0097] Continue the test for 3000 h and observe whether rust appears on the coating surface at regular intervals.

[0098] III. Surface Roughness Test

[0099] Experimental standard: Conduct surface roughness testing in accordance with ISO 25178 - 2 standard.

[0100] Experimental procedure:

[0101] (1) Coat the coatings prepared in Examples 1 - 3 and Comparative Examples 1 - 5 on the pretreated titanium alloy substrates respectively to form a coating with a thickness of about 150 μm.

[0102] (2) Cure the coating in a standard environment (temperature 23 ± 2 °C, relative humidity 50 ± 5%) for 7 days.

[0103] (3) Use an atomic force microscope to scan the coating surface and measure the surface roughness Ra value.

[0104] IV. Electrochemical Impedance Spectroscopy Test

[0105] Experimental standard: Conduct electrochemical impedance spectroscopy testing in accordance with GB / T 30789.3 - 2014 standard.

[0106] Experimental procedure:

[0107] (1) Coat the coatings prepared in Examples 1 - 3 and Comparative Examples 1 - 5 on the pretreated titanium alloy substrates respectively to form a coating with a thickness of about 150 μm.

[0108] (2) Cure the coating in a standard environment (temperature 23 ± 2 °C, relative humidity 50 ± 5%) for 7 days.

[0109] (3) Use the coated specimen as the working electrode, the saturated calomel electrode as the reference electrode, and the platinum electrode as the auxiliary electrode to conduct electrochemical impedance spectroscopy testing in 3.5% NaCl solution. The test frequency range is 10 5 - 10 -2 Hz.

[0110] The test results are shown in Table 2 below.

[0111] Table 2 Test Results of Coating Properties

[0112]

[0113]

[0114] It can be seen from the adhesion tests in Table 2 that, compared with Comparative Examples 1-5, the adhesion of Examples 1-3 is significantly higher than that of Comparative Examples 1-5, indicating that the coating of the present invention has extremely strong binding force with the substrate; then, after 3000h salt spray test, there is no rusting phenomenon in the coatings prepared in Examples 1-3, while rusting occurred in Comparative Examples 1-5 after 1500h, indicating that the present invention has good corrosion resistance.

[0115] Lower surface roughness helps to improve the appearance quality and gloss of the coating, and at the same time reduces the adhesion of dirt and corrosive media. It can be seen from the surface roughness tests in Table 2 that the Ra values of the surface roughness of Examples 1-3 are 8nm, 9nm and 7nm respectively, all at a relatively low level, indicating that the coating surface is relatively smooth, while the Ra values of the surface roughness of Comparative Examples 1-5 are basically higher than 12nm, significantly higher than those of Examples 1-3, indicating that the coating of the present invention reduces the surface roughness of the coating, which is beneficial to increasing the service life of the coating;

[0116] The higher the low-frequency impedance modulus value, the better the protective performance of the coating. It can be seen from the test results of the electrochemical impedance spectroscopy in Table 2 that the low-frequency impedance modulus values of Examples 1-3 are all at 1×108Ω·cm 2 as above, indicating that the coating has extremely high impedance performance and can effectively prevent the passage of corrosion current, while the low-frequency impedance modulus value of the coating of Comparative Example 1 is only 8×105Ω·cm 2 , that of Comparative Example 2 is 6×106Ω·cm 2 , that of Comparative Example 3 is 7×106Ω·cm 2 , that of Comparative Example 4 is 5×105Ω·cm 2 , that of Comparative Example 5 is 9×106Ω·cm 2 , indicating that the coating of the present invention can form a denser protective layer and improve the impedance performance of the coating.

[0117] In summary, the present invention constructs a multi-level rough interface by polydopamine biomimetic modification of nano-silica, combines the continuous flow process and the dual-wavelength photocuring technology to prepare a coating with high adhesion, corrosion resistance, low surface roughness and good impedance performance. The surface roughness Ra of the coating is ≤10nm, and the impedance modulus value in 3.5% NaCl solution is ≥1×10 8 Ω·cm 2 , which can be used for the corrosion-resistant coating of the alloy submarine sea valve. The coating thickness is 150-200μm, and there is no rusting after 3000h salt spray test; it can also be used for the primer coating of the carbon fiber composite body parts, and the adhesion reaches Grade 5B of ASTM D3359 standard.

[0118] In addition, it should be understood that although this specification is described in terms of embodiments, not every embodiment contains only one independent technical solution. This narrative manner of the specification is merely for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A high-adhesion acrylic paint, characterized in that, By weight, it includes 45-55 parts of acrylic resin emulsion, 10-12 parts of curing agent, 15-18 parts of pigment, 6-8 parts of modified nano-silica, 3-5 parts of hydroxyl-terminated hyperbranched polyester, 2-3 parts of dispersant, 0.8-1.2 parts of defoamer, and 1.5-2.5 parts of lithium magnesium silicate; Among them, the modified nano-silica is polydopamine / nano-silica composite particles.

2. The high-adhesion acrylic coating according to claim 1, characterized in that, By weight, it includes 50 parts of acrylic resin emulsion, 11 parts of curing agent, 16 parts of pigment, 7 parts of modified nano-silica, 4 parts of hydroxyl-terminated hyperbranched polyester, 2.5 parts of dispersant, 1 part of defoamer, and 2 parts of lithium magnesium silicate.

3. The high-adhesion acrylic paint according to claim 1 or 2, characterized in that The curing agent is an isocyanate curing agent; the pigment is titanium dioxide; the dispersant is an ammonium polycarboxylate dispersant; the defoamer is a polysiloxane defoamer.

4. The high-adhesion acrylic paint according to claim 1 or 2, characterized in that, The preparation of the modified nano-silica includes the following steps: S1. Disperse nano-silica in a buffer solution with pH = 8-9, and add dopamine hydrochloride to a concentration of 1.5-2.5 mg / mL; S2. Apply intermittent microwave radiation at 40-50 °C with 80-120 W for 6-10 h; S3. After centrifugal separation and washing with organic solvent, vacuum freeze-dry to obtain composite particles with a polydopamine coating thickness of 5-20 nm.

5. A method for preparing a high-adhesion acrylic coating according to any one of claims 1-4, characterized in that, It includes the following steps: (1) Premix the acrylic resin emulsion and modified nano-silica through a microchannel reactor; (2) Under nitrogen protection, sequentially add the curing agent, pigment and other additives using a continuous flow process; (3) Cured in segments by dual-wavelength ultraviolet LEDs: irradiation energy of 600 - 1000 mJ / cm² at 365 nm 2 followed by irradiation energy of 300 - 500 mJ / cm² at 405 nm 2 ; (4) Disperse three times with a high-pressure homogenizer until the median particle size ≤ 0.5 μm.

6. The preparation method according to claim 5, characterized in that, In step (1), the flow rate ratio of the acrylic resin emulsion to the modified nano-silica is (4-6):

1.

7. The preparation method according to claim 5, characterized in that, In step (1), the microchannel reactor adopts a 3D printed dendritic fractal structure, with a mixing efficiency ≥ 98% and a single channel length ≤ 5 cm.

8. The application of the coating according to claim 1 or 2 in offshore engineering equipment, characterized in that, Specifically used for: the corrosion-resistant coating of the seawater valve of a titanium alloy submarine, with a coating thickness of 150-200 μm and no rust after 3000 h of salt spray test.

9. The application of the coating according to claim 1 or 2 in automotive lightweighting, characterized in that, Specifically used for: the primer coating of a carbon fiber composite body part, with an adhesion reaching grade 5B of ASTM D3359 standard.

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