A protective coating for stainless steel structural surfaces and a method for making the same

Abstract

The application discloses a protective coating for a stainless steel structure surface and a preparation method thereof, and relates to the technical field of coating.The protective coating comprises a bottom layer, a surface layer and a porous ceramic particle layer arranged between the bottom layer and the surface layer.The bottom layer is made of a bottom layer coating, and the bottom layer coating comprises the following raw materials: epoxy resin E-51, butyl glycidyl ether, benzyl glycidyl ether, butyl acetate, a eutectic solvent and a curing agent dispersion liquid;the surface layer is made of a surface layer coating, and the surface layer coating comprises the following raw materials: butyl acetate, dimethylbenzene, epoxy resin E-51, a dispersant, a phenyl silicone resin dispersion liquid, silane coupling agent KH-560, a eutectic solvent, micron silicon carbide, porous ceramic particles, modified composite particles, fumed silica and a curing agent dispersion liquid.The introduction of the eutectic solvent, the porous ceramic particles and the modified composite particles and other components effectively improves the adhesion, water resistance, aging resistance and durability.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a protective coating for stainless steel structural surfaces and its preparation method. Background Technology

[0002] Stainless steel structures are often susceptible to corrosion, rust, and peeling due to environmental factors such as humid air, marine salt, and industrial acid and alkali pollutants, which can affect their performance. To address this, engineers often apply protective coatings to the surface. These coatings isolate the corrosive media from the substrate and inhibit electrochemical corrosion reactions, achieving long-term corrosion protection and extending the structural service life.

[0003] However, protective coatings for stainless steel structures still have the following performance shortcomings in practical applications: First, the adhesion between the coating and the substrate is insufficient, and it is prone to peeling and detachment under external forces such as vibration and friction; second, the waterproof performance is poor, and moisture can easily penetrate the gaps in the coating when exposed to rain for a long time; third, the resistance to ultraviolet aging is weak, and it is prone to powdering and cracking after outdoor exposure, resulting in a significant decrease in adhesion; fourth, the overall durability is insufficient, and the waterproof and protective effectiveness will rapidly decline after repeated friction, ultraviolet aging, and thermal cycling. Therefore, the adhesion, waterproofness, aging resistance, and durability of existing protective coatings for stainless steel structures still need to be improved. Summary of the Invention

[0004] The purpose of this invention is to provide a protective coating for stainless steel structural surfaces and its preparation method, thereby solving the following technical problems:

[0005] Existing protective coatings for stainless steel structures still suffer from poor adhesion, water resistance, aging resistance, and durability.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A protective coating for stainless steel structural surfaces includes a base layer, a top layer, and a porous ceramic particle layer disposed between the base layer and the top layer.

[0008] The base layer is made of a base coating, which includes the following raw materials in parts by weight: 30-35 parts of epoxy resin E-51, 5-6 parts of butyl glycidyl ether, 5-6 parts of benzyl glycidyl ether, 5-10 parts of butyl acetate, 0.5-1 parts of eutectic solvent, and 6-10 parts of curing agent dispersion.

[0009] The topcoat is made of a topcoat coating, which comprises the following raw materials in parts by weight: 25-27 parts butyl acetate, 12-14 parts xylene, 10-11 parts epoxy resin E-51, 0.2-0.3 parts dispersant, 50-60 parts phenyl silicone resin dispersion, 0.1-0.2 parts silane coupling agent KH-560, 0.5-1 parts eutectic solvent, 3-5 parts micron-sized silicon carbide, 2-3 parts porous ceramic particles, 3-4 parts modified composite particles, 0.2-0.5 parts fumed silica, and 25-30 parts curing agent dispersion.

[0010] The eutectic solvent is made of menthol and decanoic acid;

[0011] The modified composite particles are nano-silica and nano-titanium dioxide that have been pretreated with perfluorodecyltriethoxysilane and then grafted with silane coupling agent KH-560, tetraisopropyl titanate and hydroxyl-terminated polydimethylsiloxane.

[0012] Preferably, the method for preparing the eutectic solvent is as follows:

[0013] Menthol and decanoic acid were stirred at 70°C for 40-60 minutes, and then cooled to obtain a eutectic solvent.

[0014] The mass ratio of menthol to decanoic acid is 15.6:20-24.

[0015] Preferably, the modified composite particles are prepared by the following method:

[0016] A1: Nano silica and nano titanium dioxide were added to anhydrous ethanol and ultrasonically dispersed. Then deionized water was added and stirred for 10-20 min. Perfluorodecyltriethoxysilane was added and the pH was adjusted to 4-5. The mixture was then stirred and refluxed at 50°C for 2-3 h, centrifuged, washed, and dried to obtain pretreated composite particles.

[0017] A2: Add the pretreated composite particles to anhydrous ethanol and ultrasonically disperse for 60-80 min. Then add silane coupling agent KH-560 and tetraisopropyl titanate and stir at 60-70℃ for 3 h. After heating to 80℃, add hydroxyl-terminated polydimethylsiloxane and dibutyltin dilaurate and stir at 80℃ for 8-10 h. Then centrifuge, wash and dry to obtain modified composite particles.

[0018] Preferably, the mass ratio of anhydrous ethanol, nano silica, nano titanium dioxide, deionized water, and perfluorodecyltriethoxysilane in A1 is 98-100:3:2:3:0.4;

[0019] The mass ratio of anhydrous ethanol, pretreated composite particles, silane coupling agent KH-560, tetraisopropyl titanate, hydroxyl-terminated polydimethylsiloxane, and dibutyltin dilaurate in A2 is 100:5:0.3:0.15:2:0.2.

[0020] Preferably, the preparation method of the curing agent dispersion is as follows:

[0021] Polyamide 650, phenolic amine curing agent, anhydrous ethanol, and butyl acetate were mixed and stirred for 20-30 minutes to obtain a curing agent dispersion.

[0022] The mass ratio of polyamide 650, phenolic amine curing agent, anhydrous ethanol, and butyl acetate is 20-30:5:15-20:15-20.

[0023] Preferably, the preparation method of the topcoat is as follows:

[0024] B1: Add butyl acetate to anhydrous ethanol and stir until homogeneous. Then add phenyl organosilicon resin and stir for 20-30 min to obtain a phenyl organosilicon resin dispersion.

[0025] B2: Add xylene and epoxy resin E-51 to butyl acetate and stir for 20-30 min. Then add dispersant and stir for 10-12 min. Next, add phenyl organosilicon resin dispersion, silane coupling agent KH-560, and eutectic solvent and stir at 35-40℃ for 50-60 min. Then add micron-sized silicon carbide and porous ceramic particles and stir for 1-2 h. Then add modified composite particles and sonicate for 30-40 min. Finally, add fumed silica and stir for 20-30 min to obtain the surface layer composition.

[0026] B3: Mix the topcoat composition and the curing agent dispersion for 20-30 minutes to obtain the topcoat coating.

[0027] Preferably, the mass ratio of anhydrous ethanol, butyl acetate, and phenyl silicone resin in B1 is 50:50:15-20.

[0028] Preferably, the preparation method of the base coat is as follows:

[0029] Epoxy resin E-51, butyl glycidyl ether, and benzyl glycidyl ether are mixed and stirred for 10-15 minutes. Then, butyl acetate and eutectic solvent are added and stirred for 15-20 minutes. Finally, curing agent dispersion is added and stirred for 20-30 minutes to obtain the base coat.

[0030] A method for preparing a protective coating for stainless steel structural surfaces includes the following steps:

[0031] Apply a base coat to a 304 stainless steel plate and pre-cur it at 30-35℃ for 10-15 minutes. Then, evenly spread porous ceramic particles on the surface of the base coat. Stand the plate upright and gently tap it to remove loose particles. Pre-cur it at 80℃ for 15-20 minutes, then keep it at 130℃ for 40-50 minutes. After cooling, spray the top coat. Then, dry it at 80℃ for 1-1.5 hours, then keep it at 120℃ for 1-2 hours, and finally keep it at 130℃ for 1-2 hours. After cooling, a protective coating is obtained.

[0032] Preferably, the coating amount of the undercoat is 5-6 g / dm². 2 ;

[0033] The porous ceramic particles are distributed at a density of 1.2-1.5 g / dm³. 2 ;

[0034] The coating amount of the topcoat is 6-8 g / dm². 2 .

[0035] The beneficial effects of this invention are:

[0036] This invention provides a protective coating for stainless steel structural surfaces and its preparation method. The invention improves the adhesion, water resistance, aging resistance and durability of the protective coating for stainless steel structural surfaces through the following method.

[0037] (1) The eutectic solvent of this invention is compatible with epoxy resin, silicone resin, modified composite particles, and solvent, eliminating interfacial repulsion between components, reducing internal defects in the coating, and relieving internal stress. This allows the resin to form a tight bond with the 304 stainless steel substrate and the particles to form a tight bond with the resin matrix. Combined with the physical anchoring of porous ceramic particles, this effectively improves adhesion. The eutectic solvent contains long-chain alkyl groups and hydrophobic cycloalkyl groups, which are inherently hydrophobic. It can form a synergistic effect of chemical hydrophobicity and physical roughness with the modified composite particles and silicone resin, covering all hydrophilic sites on the coating surface. At the same time, it does not destroy the micro-nano rough structure formed by the porous ceramic particles, thus improving superhydrophobicity. The hydrophobic groups of the eutectic solvent can synergistically form a flexible protective film with the fluorosilicone groups of the modified particles, reducing the damage of ultraviolet rays to the resin crosslinking bonds, while maintaining the stability of the interfacial bonding and improving the adhesion retention ability. Eutectic solvents can fill the tiny gaps in the resin cross-linking network, reduce shrinkage stress during coating curing, avoid interfacial peeling or microcracks caused by internal stress, enhance the bonding force between particles and resin, reduce the shedding of modified particles and silicon carbide during friction, retain the rough structure, and improve the stability of the hydrophobic structure during friction and peeling, thereby improving durability.

[0038] (2) The epoxy groups of the silane coupling agent KH-560 in the modified composite particles of this invention can react with components such as epoxy resin E-51 and polyamide 650 to form chemical bonds, eliminating interface defects between inorganic particles and organic coatings; the modified composite particles can also fill the internal pores of the coating, reduce interfacial voids, improve the density of the coating, and further improve adhesion. The perfluorinated groups on the surface of the modified composite particles can work with polydimethylsiloxane to reduce the surface energy of the coating; at the same time, the modified composite particles will also form micro protrusions on the surface of the coating, and the scattered porous ceramic particles will form a macroscopic and microscopic double rough structure, making it impossible for water droplets to wet and improving water resistance. The nano-titanium dioxide in the modified composite particles can absorb ultraviolet rays, preventing ultraviolet rays from penetrating the coating and damaging the chemical structure of the resin matrix; the modified composite particles can form a chemical bond with the coating matrix that is resistant to ultraviolet aging, and even if the matrix is ​​slightly degraded, the interlayer bonding force can still be maintained through chemical bonds, thereby improving anti-aging properties. The nano-silica in the modified composite particles can share the stress generated by sandpaper friction, reduce surface wear of the coating, and protect the hydrophobic structure from damage; the chemical bonding makes the particles difficult to be peeled off by tape, maintaining the integrity of the surface rough structure and hydrophobic groups; the perfluorinated groups and polydimethylsiloxane have strong chemical stability and are resistant to ultraviolet aging. Even after multiple tests, they can still retain most of the hydrophobic functions, thereby improving durability.

[0039] (3) The porous ceramic particles spread in this invention can be embedded between the bottom layer and the top layer to form an interlocking structure, making it difficult for the two coating layers to separate easily, far exceeding the bonding force of simple chemical bonding; the porous structure and surface protrusions of the particles increase the contact area between the bottom layer and the top layer, making the chemical bonding more complete and improving the adhesion. The porous ceramic particle layer can provide macroscopic protrusions, which together with the microscopic protrusions provided by the modified composite particles to construct a rough surface that conforms to superhydrophobicity, so that water droplets only contact the tips of the protrusions and cannot wet, thus improving the waterproofness. The particle layer is located between the bottom layer and the top layer, blocking ultraviolet rays from directly irradiating the interlayer interface and avoiding the breakage of the chemical bonding bonds at the interface; the porous ceramic particles themselves are resistant to ultraviolet aging, and their physical interlocking structure will not fail due to ultraviolet irradiation, so that even if the surface resin undergoes slight degradation, it can still maintain the interlayer bonding force through particle anchoring. The porous ceramic particles are much harder than the coating matrix. When sandpaper is used to rub them, the raised tips of the particles will be worn down first, reducing the damage to the surface rough structure. The mechanical interlocking structure makes the top layer and the bottom layer bond very firmly, so that the tape peeling will not cause interlayer delamination, avoiding the failure of the hydrophobic surface due to interlayer separation. The rigid skeleton of the porous ceramic particle layer makes the hydrophobic groups difficult to be peeled off by external forces, while reducing the damage of ultraviolet rays to the hydrophobic groups and improving durability.

[0040] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Detailed Implementation

[0041] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. The embodiments described below 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.

[0042] Unless otherwise specified, the following information pertains to some of the raw materials used in the following embodiments and comparative examples of this invention:

[0043] Epoxy resin E-51 was purchased from Guangdong Wengjiang Chemical Reagent Co., Ltd., item number: WB98551; phenyl organosilicon resin was purchased from Shenzhen Jipeng Silicon Materials Co., Ltd.; the porous ceramic particles were CaO-Al2O3-SiO2 series porous ceramic materials, purchased from Xi'an Ruixi Biotechnology Co., Ltd., with a particle size of 50-80μm.

[0044] Example 1: A method for preparing a protective coating for stainless steel structural surfaces is as follows:

[0045] S1: Stir 15.6g of menthol and 20g of decanoic acid at 70℃ for 40min, and then cool to obtain a eutectic solvent;

[0046] S2: Add 3g of nano-silica and 2g of nano-titanium dioxide to 98g of anhydrous ethanol and disperse ultrasonically for 60min. Then add 3g of deionized water and stir for 10min. Add 0.4g of perfluorodecyltriethoxysilane and adjust the pH to 4 with acetic acid. Then stir and reflux at 50℃ for 2h, centrifuge and wash twice with anhydrous ethanol. Finally, vacuum dry at 80℃ for 12h to obtain pretreated composite particles.

[0047] S3: Add 5g of pretreated composite particles to 100g of anhydrous ethanol and ultrasonically disperse for 60min. Then add 0.3g of silane coupling agent KH-560 and 0.15g of tetraisopropyl titanate and stir at 60℃ for 3h. After heating to 80℃, add 2g of hydroxyl-terminated polydimethylsiloxane and 0.2g of dibutyltin dilaurate and stir at 80℃ for 8h. Then centrifuge and wash the precipitate three times with anhydrous ethanol mixture. Vacuum dry at 80℃ for 12h to obtain modified composite particles.

[0048] S4: Add 50g of butyl acetate to 50g of anhydrous ethanol and stir until homogeneous. Then add 15g of phenyl organosilicon resin and stir for 20min to obtain a phenyl organosilicon resin dispersion.

[0049] S5: Add 12g xylene and 10g epoxy resin E-51 to 25g butyl acetate and stir for 20min. Then add 0.2g dispersant BYK-163 and stir for 10min. Next, add 50g phenyl silicone resin dispersion, 0.1g silane coupling agent KH-560, and 0.5g eutectic solvent and stir at 35℃ for 50min. Then add 3g micron silicon carbide and 2g porous ceramic particles and stir for 1h. Then add 3g modified composite particles and sonicate for 30min. Finally, add 0.2g fumed silica and stir for 20min to obtain the surface layer composition.

[0050] S6: Mix 20g polyamide 650, 5g phenolic amine curing agent, 15g anhydrous ethanol and 15g butyl acetate and stir for 20min to obtain curing agent dispersion;

[0051] S7: Mix 106g of topcoat composition and 25g of curing agent dispersion and stir for 20 minutes to obtain the topcoat coating;

[0052] S8: Mix 30g epoxy resin E-51, 5g butyl glycidyl ether and 5g benzyl glycidyl ether and stir for 10min. Then add 5g butyl acetate and 0.5g eutectic solvent and stir for 15min to obtain the bottom layer composition.

[0053] S9: Mix 45.5g of the base coat composition and 6g of the curing agent dispersion and stir for 20 minutes to obtain the base coat coating;

[0054] S10: Apply a base coat to the 304 stainless steel sheet (coating amount: 5 g / dm). 2 After pre-curing at 30℃ for 10 minutes, porous ceramic particles are evenly spread on the surface of the base coating (spreading density of 1.2 g / dm²). 2 After standing the plant upright and gently tapping to remove loose particles, pre-cur it at 80℃ for 15 minutes, then keep it at 130℃ for 40 minutes. After cooling, spray the topcoat (coating amount 6g / dm²). 2 Then, it is dried at 80℃ for 1 hour, kept at 120℃ for 1 hour, and finally kept at 130℃ for 1 hour. After cooling, a protective coating is obtained.

[0055] Example 2: A method for preparing a protective coating for stainless steel structural surfaces is as follows:

[0056] S1: Stir 15.6g of menthol and 22g of decanoic acid at 70℃ for 50min, and then cool to obtain a eutectic solvent;

[0057] S2: Add 3g of nano-silica and 2g of nano-titanium dioxide to 99g of anhydrous ethanol and disperse ultrasonically for 70min. Then add 3g of deionized water and stir for 15min. Add 0.4g of perfluorodecyltriethoxysilane and adjust the pH to 4.5 with acetic acid. Then stir and reflux at 50℃ for 2.5h, centrifuge and wash 3 times with anhydrous ethanol. Finally, vacuum dry at 80℃ for 14h to obtain pretreated composite particles.

[0058] S3: Add 5g of pretreated composite particles to 100g of anhydrous ethanol and ultrasonically disperse for 70min. Then add 0.3g of silane coupling agent KH-560 and 0.15g of tetraisopropyl titanate and stir at 65℃ for 3h. After heating to 80℃, add 2g of hydroxyl-terminated polydimethylsiloxane and 0.2g of dibutyltin dilaurate and stir at 80℃ for 9h. Then centrifuge and wash the precipitate 4 times with anhydrous ethanol mixture. Vacuum dry at 80℃ for 14h to obtain modified composite particles.

[0059] S4: Add 50g of butyl acetate to 50g of anhydrous ethanol and stir until homogeneous. Then add 18g of phenyl organosilicon resin and stir for 25min to obtain a phenyl organosilicon resin dispersion.

[0060] S5: Add 13g xylene and 10.5g epoxy resin E-51 to 26g butyl acetate and stir for 25min. Then add 0.25g dispersant BYK-163 and stir for 11min. Next, add 55g phenyl silicone resin dispersion, 0.15g silane coupling agent KH-560, and 0.8g eutectic solvent and stir at 38℃ for 55min. Then add 4g micron silicon carbide and 2.5g porous ceramic particles and stir for 1.5h. Then add 3.5g modified composite particles and sonicate for 35min. Finally, add 0.4g fumed silica and stir for 25min to obtain the surface layer composition.

[0061] S6: Mix 25g polyamide 650, 5g phenolic amine curing agent, 18g anhydrous ethanol and 18g butyl acetate and stir for 25min to obtain curing agent dispersion;

[0062] S7: Mix 116g of topcoat composition and 28g of curing agent dispersion and stir for 25 minutes to obtain the topcoat coating;

[0063] S8: Mix 32.5g epoxy resin E-51, 5.5g butyl glycidyl ether and 5.5g benzyl glycidyl ether and stir for 13min. Then add 7.5g butyl acetate and 0.8g eutectic solvent and stir for 18min to obtain the bottom layer composition.

[0064] S9: Mix 51.8g of the base composition and 8g of the curing agent dispersion and stir for 25 minutes to obtain the base coating;

[0065] S10: Apply a base coat to 304 stainless steel sheet (coating amount: 5.5 g / dm²). 2 After pre-curing at 33℃ for 13 minutes, porous ceramic particles are evenly spread on the surface of the base coating (spreading density of 1.4 g / dm²). 2 After standing it up and gently tapping to remove loose particles, pre-cur it at 80℃ for 18 minutes, then keep it at 130℃ for 45 minutes. After cooling, spray the topcoat (coating amount is 7g / dm²). 2 Then, it is dried at 80℃ for 1.3 hours, then kept at 120℃ for 1.5 hours, and finally kept at 130℃ for 1.5 hours. After cooling, a protective coating is obtained.

[0066] Example 3: A method for preparing a protective coating for the surface of a stainless steel structure is as follows:

[0067] S1: Stir 15.6g of menthol and 24g of decanoic acid at 70℃ for 60min, and then cool to obtain a eutectic solvent;

[0068] S2: Add 3g of nano-silica and 2g of nano-titanium dioxide to 100g of anhydrous ethanol and disperse ultrasonically for 80min. Then add 3g of deionized water and stir for 20min. Add 0.4g of perfluorodecyltriethoxysilane and adjust the pH to 5 with acetic acid. Then stir and reflux at 50℃ for 3h, centrifuge and wash 4 times with anhydrous ethanol. Finally, vacuum dry at 80℃ for 15h to obtain pretreated composite particles.

[0069] S3: Add 5g of pretreated composite particles to 100g of anhydrous ethanol and ultrasonically disperse for 80min. Then add 0.3g of silane coupling agent KH-560 and 0.15g of tetraisopropyl titanate and stir at 70℃ for 3h. After heating to 80℃, add 2g of hydroxyl-terminated polydimethylsiloxane and 0.2g of dibutyltin dilaurate and stir at 80℃ for 10h. Then centrifuge and wash the precipitate 5 times with anhydrous ethanol mixture. Vacuum dry at 80℃ for 15h to obtain modified composite particles.

[0070] S4: Add 50g of butyl acetate to 50g of anhydrous ethanol and stir until homogeneous. Then add 20g of phenyl organosilicon resin and stir for 30min to obtain a phenyl organosilicon resin dispersion.

[0071] S5: Add 14g xylene and 11g epoxy resin E-51 to 27g butyl acetate and stir for 30min. Then add 0.3g dispersant BYK-163 and stir for 12min. Next, add 60g phenyl silicone resin dispersion, 0.2g silane coupling agent KH-560, and 1g eutectic solvent and stir at 40℃ for 60min. Then add 5g micron silicon carbide and 3g porous ceramic particles and stir for 2h. Then add 4g modified composite particles and sonicate for 40min. Finally, add 0.5g fumed silica and stir for 30min to obtain the surface layer composition.

[0072] S6: Mix 30g polyamide 650, 5g phenolic amine curing agent, 20g anhydrous ethanol and 20g butyl acetate and stir for 30min to obtain curing agent dispersion;

[0073] S7: Mix 126g of topcoat composition and 30g of curing agent dispersion and stir for 30 minutes to obtain the topcoat coating;

[0074] S8: Mix 35g of epoxy resin E-51, 6g of butyl glycidyl ether and 6g of benzyl glycidyl ether and stir for 15min. Then add 10g of butyl acetate and 1g of eutectic solvent and stir for 20min to obtain the bottom layer composition.

[0075] S9: Mix 58g of the base composition and 10g of the curing agent dispersion and stir for 30 minutes to obtain the base coating;

[0076] S10: Apply a base coat to 304 stainless steel sheet (coating amount 6g / dm). 2 After pre-curing at 35℃ for 15 minutes, porous ceramic particles are evenly spread on the surface of the base coating (spreading density of 1.5 g / dm²). 2 After standing the plant upright and gently tapping to remove loose particles, pre-cur it at 80℃ for 20 minutes, then keep it at 130℃ for 50 minutes. After cooling, spray the topcoat (coating amount 8g / dm²). 2 Then, it is dried at 80℃ for 1.5 hours, then kept at 120℃ for 2 hours, and finally kept at 130℃ for 2 hours. After cooling, a protective coating is obtained.

[0077] Comparative Example 1:

[0078] Compared with Example 1, this comparative example only replaces the "5g pretreatment composite particles" added in the preparation process of S3 with "3g nano silicon dioxide and 2g nano titanium dioxide". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, a protective coating for stainless steel structure surface is obtained.

[0079] Comparative Example 2:

[0080] Compared with Example 1, this comparative example only omits the addition of "eutectic solvent" in the preparation process of S5. All other steps and parameters are the same, and will not be repeated here. The final result is a protective coating for the surface of stainless steel structures.

[0081] Comparative Example 3:

[0082] Compared with Example 1, this comparative example only replaces the "modified composite particles" added in the preparation process of S5 with "pretreated composite particles". All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, a protective coating for stainless steel structure surface is obtained.

[0083] Comparative Example 4:

[0084] Compared with Example 1, this comparative example only did not include the sprinkling of "porous ceramic particles" during the preparation process of S10. All other steps and parameters were the same, and will not be repeated here. The final result was a protective coating for the surface of a stainless steel structure.

[0085] Performance testing:

[0086] Adhesion determination:

[0087] According to the GB / T 9286-2021 cross-cut adhesion test standard, the adhesion grade (level) of the protective coatings for stainless steel structural surfaces prepared in Examples 1-3 and Comparative Examples 1-4 of this invention was determined, and the test results are shown in Table 1.

[0088] Water resistance testing:

[0089] The water contact angle WCA (°) and roll-off angle WSA (°) of the protective coatings for stainless steel structures prepared in Examples 1-3 and Comparative Examples 1-4 of the present invention were measured, and the test results are shown in Table 1.

[0090] Determination of anti-aging properties:

[0091] The protective coatings on the surface of the stainless steel structures prepared in Examples 1-3 and Comparative Examples 1-4 of this invention were measured at a wavelength of 254 nm and an irradiation intensity of 14.15 W / m. 2 The adhesion (grade) after 192 hours of UV irradiation under a UV lamp is shown in Table 1.

[0092] Durability testing:

[0093] The protective coatings on the stainless steel structures prepared in Examples 1-3 and Comparative Examples 1-4 of this invention were measured to have a wear resistance of 14.15 W / m² after 20 μm of friction with 100 grit sandpaper and a 100 g weight, 30 peels with 3M tape, and irradiation at a wavelength of 254 nm. 2The water contact angle (°) of the coating surface after 192 hours of ultraviolet irradiation under a UV lamp is shown in Table 1.

[0094] Table 1: Performance test results of Examples 1-3 and Comparative Examples 1-4

[0095]

[0096] Data Analysis:

[0097] As can be seen from Table 1, the protective coating for stainless steel structures prepared in the embodiments of the present invention has excellent adhesion, water resistance, anti-aging properties and durability.

[0098] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A protective coating for stainless steel structural surfaces, characterized by, The bottom layer, the surface layer and the porous ceramic particle layer arranged between the bottom layer and the surface layer; The bottom layer is made of a bottom layer coating, and the bottom layer coating comprises the following raw materials in parts by mass: epoxy resin E-51 30-35 parts, butyl glycidyl ether 5-6 parts, benzyl glycidyl ether 5-6 parts, butyl acetate 5-10 parts, eutectic solvent 0.5-1 part, and curing agent dispersion 6-10 parts; The surface layer is made of a surface layer coating, and the surface layer coating comprises the following raw materials in parts by mass: butyl acetate 25-27 parts, xylene 12-14 parts, epoxy resin E-51 10-11 parts, dispersant 0.2-0.3 parts, phenyl silicone resin dispersion 50-60 parts, silane coupling agent KH-560 0.1-0.2 parts, eutectic solvent 0.5-1 part, micron silicon carbide 3-5 parts, porous ceramic particles 2-3 parts, modified composite particles 3-4 parts, fumed silica 0.2-0.5 parts, and curing agent dispersion 25-30 parts; The eutectic solvent is made of menthol and decanoic acid; The modified composite particles are nano-silica and nano-titanium dioxide which are pretreated by perfluorodecyltriethoxysilane and then grafted and modified by silane coupling agent KH-560, tetraisopropyl titanate and hydroxyl-terminated polydimethylsiloxane.

2. The protective coating for stainless steel structural surfaces according to claim 1, characterized in that, The preparation method of the eutectic solvent is as follows: The menthol and decanoic acid are stirred at 70℃ for 40-60min, and the eutectic solvent is obtained after cooling; The mass ratio of the menthol to the decanoic acid is 15.6:20-24.

3. The protective coating for stainless steel architectural surfaces according to claim 1, characterized in that, The preparation method of the modified composite particles is as follows: A1: nano-silica and nano-titanium dioxide are added in anhydrous ethanol and ultrasonically dispersed, then deionized water is added and stirred for 10-20min, perfluorodecyltriethoxysilane is added and the pH is adjusted to 4-5, then the mixture is stirred and refluxed at 50℃ for 2-3h, centrifuged, washed and dried to obtain pretreated composite particles; A2: the pretreated composite particles are added in anhydrous ethanol and ultrasonically dispersed, then silane coupling agent KH-560 and tetraisopropyl titanate are added and stirred at 60-70℃ for 3h, hydroxyl-terminated polydimethylsiloxane and dibutyltin dilaurate are added after the temperature is raised to 80℃ and stirred for 8-10h, then the mixture is centrifuged, washed and dried to obtain modified composite particles.

4. The protective coating for stainless steel structural surfaces according to claim 3, characterized in that, The mass ratio of the anhydrous ethanol, nano-silica, nano-titanium dioxide, deionized water and perfluorodecyltriethoxysilane in A1 is 98-100:3:2:3:0.4; The mass ratio of the anhydrous ethanol, pretreated composite particles, silane coupling agent KH-560, tetraisopropyl titanate, hydroxyl-terminated polydimethylsiloxane and dibutyltin dilaurate in A2 is 100:5:0.3:0.15:2:0.

2.

5. The protective coating for stainless steel architectural surfaces of claim 1, wherein The preparation method of the curing agent dispersion is as follows: Polyamide 650, phenolic amine curing agent, anhydrous ethanol and butyl acetate are mixed and stirred for 20-30min to obtain the curing agent dispersion; The mass ratio of the polyamide 650, phenolic amine curing agent, anhydrous ethanol and butyl acetate is 20-30:5:15-20:15-20.

6. The protective coating for stainless steel architectural surfaces of claim 1, wherein The preparation method of the surface layer coating is as follows: B1: Butyl acetate was added to anhydrous ethanol and stirred until uniform, then the phenyl silicone resin was added and stirred for 20-30 min to obtain a phenyl silicone resin dispersion; B2: Xylene, epoxy resin E-51 were added to butyl acetate and stirred for 20-30 min, then the dispersant was added and stirred for 10-12 min, then the phenyl silicone resin dispersion, silane coupling agent KH-560, and eutectic solvent were added and stirred at 35-40℃ for 50-60 min, then micron silicon carbide and porous ceramic particles were added and stirred for 1-2 h, then the modified composite particles were added and ultrasonicated for 30-40 min, and finally fumed silica was added and stirred for 20-30 min to obtain a top layer composition; B3: The top layer composition and curing agent dispersion were mixed and stirred for 20-30 min to obtain a top layer coating.

7. The protective coating for stainless steel architectural surfaces according to claim 6, characterized in that, The mass ratio of the anhydrous ethanol, butyl acetate, and phenyl silicone resin in B1 is 50:50:15-20.

8. The protective coating for stainless steel architectural surfaces of claim 1, wherein, The bottom layer coating was prepared as follows: Epoxy resin E-51, butyl glycidyl ether, and benzyl glycidyl ether were mixed and stirred for 10-15 min, then butyl acetate and eutectic solvent were added and stirred for 15-20 min, then the curing agent dispersion was added and stirred for 20-30 min to obtain a bottom layer coating.

9. A method for producing a protective coating for a stainless steel structure surface according to any one of claims 1 to 8, characterized by, The method comprises the following steps: The bottom layer coating was applied to a stainless steel plate, and after pre-curing at 30-35℃, the porous ceramic particles were evenly spread on the surface of the bottom layer coating, and after being stood up and tapped to remove the floating particles, it was cured, then the top layer coating was sprayed and cured, and after cooling, a protective coating was obtained. The method comprises the following steps: The bottom layer coating was applied to a stainless steel plate, and after pre-curing at 30-35℃, the porous ceramic particles were evenly spread on the surface of the bottom layer coating, and after being stood up and tapped to remove the floating particles, it was cured, then the top layer coating was sprayed and cured, and after cooling, a protective coating was obtained.

10. The method of producing a protective coating for stainless steel structural surfaces according to claim 9, characterized by, The coating amount of the base coat is 5-6 g / dm 2 ; The bulk density of the porous ceramic particles is 1.2-1.5 g / dm 2 ; The coating amount of the top coat is 6-8 g / dm 2 .

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