Organic-inorganic hybrid long-acting anticorrosive paint as well as preparation method and application thereof

Abstract

The invention provides an organic-inorganic hybrid long-acting anticorrosive coating as well as a preparation method and application thereof, and belongs to the technical field of coating preparation. According to the invention, the organic-inorganic hybrid long-acting anticorrosive paint with stable performance is designed and constructed from the molecular level and the nanoscale, and methyltrimethoxysilane is introduced by chemical reaction; during film forming, the organic-inorganic hybrid long-acting anticorrosive paint is constructed by utilizing hydrolysis and condensation of silicon hydroxyl in nano silica sol and hydrolysis and condensation of silanol formed by hydrolysis of silicon hydroxyl and methyltrimethoxysilane, so that the problem of poor binding force between a coating and a metal substrate interface as well as between resin and filler is effectively solved; the coating has excellent weather resistance, corrosion resistance, high temperature resistance and wear resistance, and the all-weather corrosion resistance of the coating is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of coating preparation, and particularly to an organic-inorganic hybrid long-acting anti-corrosion coating, a preparation method thereof, and an application thereof. Background Art

[0002] Thermal power plants are key facilities for modern energy supply, including metal equipment made of metal materials such as boilers, steam turbines, electrostatic precipitators, desulfurization and denitrification devices, coal conveying systems, and step-up substations. Although these metal equipment have undergone anti-corrosion treatment, in the actual operation of thermal power plants, due to the extremely harsh environment, the metal equipment is long-term faced with various forms of corrosion problems, including low-temperature corrosion, acid-base corrosion, electrochemical corrosion, and salt spray corrosion, etc. Long-term corrosion will damage the anti-corrosion layer on the surface of the metal equipment, and the unprotected metal equipment will be damaged under the action of corrosion, which will not only seriously affect the performance and service life of the metal equipment, but also lead to equipment failures and production stoppages, and even safety accidents, causing huge economic losses and safety risks.

[0003] Coating an anti-corrosion coating on the surface of metal equipment is the main means to improve the anti-corrosion performance of metal equipment. Traditional anti-corrosion coatings generally use polyurea, epoxy resin, and polyurethane as raw materials. These anti-corrosion coatings have problems such as poor adhesion to the substrate, easy contamination of the coating, and easy peeling and cracking of the coating in a complex environment, resulting in limited anti-corrosion effect and service life. Existing anti-corrosion technologies cannot achieve continuous and effective protection. Especially in a high-corrosion environment, the maintenance cycle of the anti-corrosion coating is too short, and there are challenges in the adhesion and pollution resistance of the coating. Therefore, the metal equipment in thermal power plants needs to be periodically subjected to anti-corrosion operations. Generally, a comprehensive anti-corrosion operation needs to be carried out every about 5 years. Since most of the anti-corrosion work of thermal power plant equipment belongs to high-altitude operations or has complex structures, the working environment is harsh, there are relatively high safety risks, and the anti-corrosion operation cycle is short and the replacement work cycle is frequent, which brings huge labor costs, time costs, and safety hazards to enterprises.

[0004] As an excellent coating material, the polyurea coating formed by polyurea materials has good thermal stability, abrasion resistance, waterproof and anti-pollution properties, etc. And it is not sensitive to environmental changes, can maintain good performance under a wide range of temperature and humidity changes. At the same time, the elastic characteristics of the polyurea coating enable it to adapt to the expansion and contraction of the substrate, and can effectively slow down the erosion of the external environment on metal components. However, existing polyurea coatings still have problems such as easy contamination and insufficient adhesion between the coating and the substrate, resulting in a great impact on their anti-corrosion performance, which limits their application effect in the field of long-term anti-corrosion.

[0005] Therefore, how to improve the corrosion resistance of the coating and the adhesion between the coating and the substrate has become an urgent technical problem in this field. Summary of the Invention

[0006] The object of the present invention is to provide an organic-inorganic hybrid long-acting anti-corrosion coating, its preparation method and application. The coating formed by the organic-inorganic hybrid long-acting anti-corrosion coating provided by the present invention can effectively resist various corrosion forms such as acid-base corrosion, electrochemical corrosion and low-temperature corrosion, and can provide effective protection for more than 15 years in harsh environments.

[0007] In order to achieve the above-mentioned invention object, the present invention provides the following technical solutions:

[0008] The present invention provides a preparation method of an organic-inorganic hybrid long-acting anti-corrosion coating, including the following steps:

[0009] (1) Mix polyetheramine, silica sol and isophorone diisocyanate to obtain a nano-silica sol modified isocyanate prepolymer;

[0010] (2) Mix terminal amino polyether, amine chain extender and methyltrimethoxysilane to obtain an organosilicon modified amino polyether system;

[0011] (3) Mix the nano-silica sol modified isocyanate prepolymer obtained in step (1) and the organosilicon modified amino polyether system obtained in step (2), and then carry out hydrolysis reaction and condensation reaction in sequence to obtain an organic-inorganic hybrid long-acting anti-corrosion coating;

[0012] Steps (1) and (2) are not in a specific order.

[0013] Preferably, in step (1), the molecular weight of polyetheramine is 2000 - 4000, and the particle size of silica sol is 10 - 100 nm.

[0014] Preferably, in step (1), the mass ratio of polyetheramine to silica sol is 1:(0.1 - 1).

[0015] Preferably, in step (1), the mass ratio of isophorone diisocyanate to polyetheramine is 1:(1 - 1.5).

[0016] Preferably, in step (2), the mass ratio of terminal amino polyether to amine chain extender is (8 - 20):(1 - 2).

[0017] Preferably, in step (2), the mass ratio of terminal amino polyether to methyltrimethoxysilane is (8 - 20):(0.5 - 1).

[0018] Preferably, in step (3), the mass ratio of the nano-silica sol modified isocyanate prepolymer to the organosilicon modified amino polyether system is (1 - 3):1.

[0019] Preferably, in the step (3), the temperature of the hydrolysis reaction is 40 - 60 °C, and the pH value of the hydrolysis reaction is 4 - 6; the temperature of the condensation reaction is 60 - 80 °C, and the time of the condensation reaction is 60 - 90 min.

[0020] The present invention provides an organic-inorganic hybrid long-acting anti-corrosion coating prepared by the preparation method described in the above technical solution.

[0021] The present invention provides the application of the organic-inorganic hybrid long-acting anti-corrosion coating described in the above technical solution in the metal facilities of a thermal power plant, and the metal facilities of the thermal power plant include a boiler furnace, a main steel frame of an electrostatic precipitator, a desulfurization absorption tower and its surrounding corrosive environment, underground pipelines and outdoor pipelines.

[0022] The present invention provides a preparation method of an organic-inorganic hybrid long-acting anti-corrosion coating, comprising the following steps:

[0023] (1) Mix polyetheramine, silica sol and isophorone diisocyanate to obtain a nano-silica sol modified isocyanate prepolymer; (2) Mix an amino-terminated polyether, an amine chain extender and methyltrimethoxysilane to obtain an organosilicon modified amino polyether system; (3) Mix the nano-silica sol modified isocyanate prepolymer obtained in the step (1) and the organosilicon modified amino polyether system obtained in the step (2), and then carry out a hydrolysis reaction and a condensation reaction in sequence to obtain an organic-inorganic hybrid long-acting anti-corrosion coating; the step (1) and the step (2) are not in a sequential order. The present invention designs and constructs a stable organic-inorganic hybrid long-acting anti-corrosion coating at the molecular level and nano-scale, introduces methyltrimethoxysilane by chemical reaction, and uses the hydrolysis and condensation of silanol groups in the nano-silica sol and the hydrolysis and condensation between the silanol groups formed by the hydrolysis of methyltrimethoxysilane during film formation to construct the organic-inorganic hybrid long-acting anti-corrosion coating, effectively solving the problem of poor bonding force between the coating and the metal substrate and between the resin and the filler. The coating has excellent weather resistance, corrosion resistance, high temperature resistance and abrasion resistance, significantly improving the all-weather anti-corrosion performance of the coating.

[0024] The preparation method provided by the present invention is simple and low-cost, has broad application prospects, and the anti-corrosion effect of the coating is remarkable. It can achieve anti-corrosion protection for metal components for more than 15 years through a single coating, greatly reducing the frequency of anti-corrosion operations and the risk of high-altitude operations, improving the safety and economy of thermal power plant equipment. Through this long-acting anti-corrosion technology, the equipment maintenance cost of thermal power plants can be effectively reduced, the operation efficiency of equipment can be improved, and contributions can be made in terms of environmental protection.

[0025] The results of the examples show that the coating formed by the organic-inorganic hybrid long-acting anti-corrosion coating provided by the present invention can effectively resist various corrosion forms such as acid-base corrosion, electrochemical corrosion and low-temperature corrosion, and can provide effective protection for more than 15 years in a harsh environment. Detailed implementation manners

[0026] The present invention provides a preparation method of an organic-inorganic hybrid long-acting anti-corrosion coating, comprising the following steps:

[0027] (1) Mix polyetheramine, silica sol and isophorone diisocyanate to obtain a nano-silica sol modified isocyanate prepolymer;

[0028] (2) Mix an amino-terminated polyether, an amine chain extender and methyltrimethoxysilane to obtain an organosilicon modified amino polyether system;

[0029] (3) Mix the nano-silica sol modified isocyanate prepolymer obtained in the step (1) and the organosilicon modified amino polyether system obtained in the step (2), and then successively carry out a hydrolysis reaction and a condensation reaction to obtain an organic-inorganic hybrid long-acting anti-corrosion coating;

[0030] The step (1) and the step (2) are not in a specific order.

[0031] In the present invention, unless otherwise specified, the raw materials used are commercially available products well-known to those skilled in the art.

[0032] The present invention mixes polyetheramine, silica sol and isophorone diisocyanate (IPDI) to obtain a nano-silica sol modified isocyanate prepolymer.

[0033] In the present invention, the molecular weight of the polyetheramine is preferably 2000-4000. As an embodiment of the present invention, the molecular weight of the polyetheramine can be 2000, 2200, 2500, 2800, 3000, 3200, 3500, 3800 or 4000.

[0034] In the present invention, the particle size of the silica sol is preferably 10-100 nm. As an embodiment of the present invention, the particle size of the silica sol can be 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm or 100 nm. By controlling the particle size of the silica sol, the corrosion resistance and wear resistance of the coating can be further improved.

[0035] In the present invention, the mass ratio of the polyetheramine to the silica sol is preferably 1:(0.1 - 1); the mass ratio of the isophorone diisocyanate to the polyetheramine is preferably 1:(1 - 1.5). As an embodiment of the present invention, the mass ratio of the polyetheramine to the silica sol can be 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9 or 1:1; the mass ratio of the isophorone diisocyanate to the polyetheramine can be 1:(1.1 - 1.4), and can also be 1:(1.2 - 1.3). By controlling the dosages of the polyetheramine, the silica sol and the isophorone diisocyanate, the present invention can further improve the performance stability of the coating, thereby improving the weather resistance, corrosion resistance, high temperature resistance and abrasion resistance of the coating.

[0036] In the present invention, the preferred way of mixing the polyetheramine, the silica sol and the isophorone diisocyanate is: under stirring conditions, the silica sol is added dropwise to the polyetheramine, then heated to 50 - 80°C and kept warm for 15 - 60 min, then cooled to ≤40°C and the isophorone diisocyanate is added, and stirred for 40 - 100 min to obtain a nano-silica sol modified isocyanate prepolymer.

[0037] The present invention has no special limitation on the stirring rate, which is determined according to the common technical knowledge of those skilled in the art and can avoid splashing. The present invention realizes the mixing of the polyetheramine, the silica sol and the isophorone diisocyanate under stirring conditions, which is beneficial to promoting the more uniform mixing of each component.

[0038] The present invention has no special limitation on the dropping rate of the silica sol, which can be determined according to the common technical knowledge of those skilled in the art. By adding the silica sol dropwise to the polyetheramine, the present invention is beneficial to the better dispersion of the silica sol in the polyetheramine system.

[0039] In the present invention, the heating temperature can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C; the heat preservation time can be 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min or 60 min. After adding the silica sol dropwise to the polyetheramine, the present invention conducts heating and heat preservation. At a relatively high temperature, through continuous stirring, nano-particles can be fully dispersed in the polyetheramine system.

[0040] The present invention has no special limitation on the adding rate of the isophorone diisocyanate, which is determined according to the technology of those skilled in the art and can be added slowly.

[0041] The present invention does not have special limitations on the stirring rate after adding isophorone diisocyanate, which is determined according to the common technical knowledge of those skilled in the art, as long as splashing can be avoided and each component can be evenly mixed. As an embodiment of the present invention, the stirring time after adding isophorone diisocyanate can be 40 min, 45 min, 50 min, 55 min, 60 min, 65 min, 70 min, 75 min, 80 min, 85 min, 90 min, 95 min or 100 min.

[0042] The present invention preferably stores the nano-silica sol modified isocyanate prepolymer in a sealed manner. The present invention does not have special limitations on the specific operation of the sealed storage, and any sealed storage method well-known to those skilled in the art can be used.

[0043] The present invention mixes a terminal amino polyether, an amine chain extender and methyltrimethoxysilane to obtain an organosilicon-modified amino polyether system.

[0044] In the present invention, the molecular weight of the terminal amino polyether is preferably 2000 - 4000. As an embodiment of the present invention, the molecular weight of the terminal amino polyether can be 2000, 2200, 2500, 2800, 3000, 3200, 3500, 3800 or 4000.

[0045] In the present invention, the amine chain extender is preferably amine chain extender E100, E300, diethylenetriamine or 3,3-dichloro-4,4-diaminodiphenylmethane diamine (MOCA), and more preferably amine chain extender E300. By controlling the type of the amine chain extender, the present invention can further improve the corrosion resistance of the coating.

[0046] In the present invention, the mass ratio of the terminal amino polyether to the amine chain extender is preferably (8 - 20):(1 - 2); the mass ratio of the terminal amino polyether to methyltrimethoxysilane is preferably (8 - 20):(0.5 - 1). As an embodiment of the present invention, the mass ratio of the terminal amino polyether to the amine chain extender can be (10 - 15):(1 - 1.5), and can also be (12 - 13):(1 - 1.5); the mass ratio of the terminal amino polyether to methyltrimethoxysilane can be (10 - 15):(0.6 - 0.8), and can also be (12 - 13):(0.6 - 0.7). By controlling the dosages of each component, after the formed organosilicon-modified amino polyether system is mixed with the nano-silica sol modified isocyanate prepolymer, the hydrolysis reaction and condensation reaction can be carried out to further improve the corrosion resistance of the coating and improve the adhesion of the coating to the substrate.

[0047] In the present invention, the preferred way of mixing the amino-terminated polyether, amine chain extender and methyltrimethoxysilane is as follows: first mix the amino-terminated polyether and amine chain extender and stir for 15 - 30 min, then add methyltrimethoxysilane and continue stirring for 15 - 30 min to obtain an organosilicon-modified amino polyether system.

[0048] The present invention has no special limitation on the addition rate of the methyltrimethoxysilane, and it can be determined according to the common technical knowledge of those skilled in the art.

[0049] The present invention has no special limitation on the stirring rate, and it can be determined according to the common technical knowledge of those skilled in the art as long as the components can be mixed evenly.

[0050] After obtaining the nano-silica sol-modified isocyanate prepolymer and the organosilicon-modified amino polyether system, the present invention mixes the nano-silica sol-modified isocyanate prepolymer and the organosilicon-modified amino polyether system and then conducts hydrolysis reaction and condensation reaction in sequence to obtain an organic-inorganic hybrid long-lasting anti-corrosion coating.

[0051] In the present invention, the mass ratio of the nano-silica sol-modified isocyanate prepolymer to the organosilicon-modified amino polyether system is preferably (1 - 3):1, more preferably 2:1. By controlling the dosage relationship between the two, the present invention can further improve the corrosion resistance and high-temperature resistance of the organic-inorganic hybrid long-lasting anti-corrosion coating, and at the same time improve the adhesion between the coating and the substrate.

[0052] In the present invention, the preferred way of mixing the nano-silica sol-modified isocyanate prepolymer and the organosilicon-modified amino polyether system is as follows: under stirring conditions, drop the organosilicon-modified amino polyether system into the nano-silica sol-modified isocyanate prepolymer. The present invention has no special limitation on the stirring rate as long as the nano-silica sol-modified isocyanate prepolymer and the organosilicon-modified amino polyether system can be mixed evenly. The present invention has no special limitation on the dropping rate, and it can be determined according to the common technical knowledge of those skilled in the art.

[0053] In the present invention, the temperature of the hydrolysis reaction is preferably 40 to 60 °C; the pH value of the hydrolysis reaction is preferably 4 to 6; the temperature of the condensation reaction is preferably 60 to 80 °C; the time of the condensation reaction is preferably 60 to 90 min. As an embodiment of the present invention, the temperature of the hydrolysis reaction can be 45 °C, 50 °C or 55 °C; the pH value of the hydrolysis reaction can be 4.5, 5 or 5.5; the temperature of the condensation reaction can be 65 °C, 70 °C or 75 °C; the time of the condensation reaction can be 65 min, 70 min, 75 min, 80 min or 85 min. The present invention has no special limitation on the time of the hydrolysis reaction, which can be determined according to the common technical knowledge of those skilled in the art. By carrying out the hydrolysis reaction under weak acid conditions, the weak acidic environment is beneficial to the progress of the hydrolysis reaction; by controlling the parameters of the condensation reaction, sufficient crosslinking can be ensured; through the above hydrolysis and condensation reactions, the present invention constructs a stable organic-inorganic hybrid network structure at the molecular level and nanoscale, significantly improving the corrosion resistance and adhesion of the coating. Specifically, the coating shows no corrosion after being immersed in 10% H 2 SO 4 solution for 30 days, and the corrosion rate is ≤ 0.01 mm / year; the bonding strength between the coating and the metal substrate reaches 18 MPa, far higher than 5 - 8 MPa of the conventional coating.

[0054] In the present invention, the hydrolysis reaction and the condensation reaction include the following processes:

[0055] 1) Hydrolysis of silica sol

[0056] The silanol groups (Si-OH) in the silica sol are further hydrolyzed under the action of water to form silanol (Si(OH) 4 ), and the reaction equation is as follows:

[0057] Si-OH + H 2 O → Si(OH) 4 ;

[0058] 2) Hydrolysis of methyltrimethoxysilane

[0059] Methyltrimethoxysilane (MTMS) is hydrolyzed under the action of water to form silanol (CH 3 Si(OH) 3 ) and methanol, and the reaction equation is as follows:

[0060] CH 3 Si(OCH 3 ) 3 + H 2 O → CH 3 Si(OH) 3 + CH 3 OH;

[0061] 3) Condensation between silanols

[0062] The silanols (Si(OH) 4 and CH 3 Si(OH) 3 ) produced by hydrolysis undergo a condensation reaction to form stable silicon-oxygen bonds (Si-O-Si) and release water. The reaction equation is as follows:

[0063] Si(OH) 4 +Si(OH) 4 →Si-O-Si+H 2 O

[0064] CH 3 Si(OH) 3 +CH 3 Si(OH) 3 →CH 3 Si-O-SiCH 3 +H 2 O;

[0065] 4) Condensation between silanol and isocyanate prepolymer

[0066] The silanol reacts with the -NCO group in the isocyanate prepolymer to form Si-O-C bonds, further enhancing the crosslinking density and interfacial bonding strength of the coating. The reaction equation is as follows:

[0067] Si-OH+R-NCO→Si-O-C(O)-NH-R.

[0068] The present invention designs and constructs an organic-inorganic hybrid long-lasting anti-corrosion coating with stable performance at the molecular level and nanoscale. By introducing methyltrimethoxysilane through a chemical reaction, during film formation, the hydrolysis and condensation of silanol groups in nano-silica sol and the hydrolysis and condensation between silanol groups and silanols formed by the hydrolysis of methyltrimethoxysilane are utilized to construct the organic-inorganic hybrid long-lasting anti-corrosion coating, effectively solving the problem of poor bonding strength between the coating and the metal substrate interface and between the resin and the filler. The coating has excellent weather resistance, corrosion resistance, high-temperature resistance, and abrasion resistance, significantly improving the all-weather anti-corrosion performance of the coating.

[0069] The present invention combines polyurea with organosilicon materials and introduces inorganic components such as silica sol to prepare an organic-inorganic hybrid polyurea coating, significantly improving the anti-corrosion performance of the polyurea coating; while improving the corrosion resistance, abrasion resistance, and high-temperature resistance of the polyurea coating, the adhesion between the coating and the metal substrate is enhanced, and the problems of easy contamination and poor adhesion of the coating are solved.

[0070] The preparation method provided by the present invention is simple, with low cost, and the anti-corrosion effect of the coating is remarkable. It can achieve anti-corrosion protection for metal components for more than 15 years through a single coating, greatly reducing the frequency of anti-corrosion operations and the risk of high-altitude operations, improving the safety and economy of thermal power plant equipment. Through this long-term anti-corrosion technology, the equipment maintenance cost of thermal power plants can be effectively reduced, the operation efficiency of equipment can be improved, and contributions can be made in terms of environmental protection.

[0071] The present invention also provides an organic-inorganic hybrid long-term anti-corrosion coating prepared by the preparation method described in the above technical solution.

[0072] The coating formed by the organic-inorganic hybrid long-term anti-corrosion coating provided by the present invention can effectively resist various corrosion forms such as acid-base corrosion, electrochemical corrosion, and low-temperature corrosion, and can provide effective protection for more than 15 years in a harsh environment.

[0073] The present invention also provides the application of the organic-inorganic hybrid long-term anti-corrosion coating described in the above technical solution in the metal facilities of thermal power plants.

[0074] In the present invention, the metal facilities of the thermal power plant preferably include boilers, steam turbines, condensers, pipelines, electrostatic precipitators, desulfurization and denitrification devices, coal conveying systems, and step-up substations.

[0075] In the present invention, the preferred application method is as follows: First, pre-treat the area to be coated, then apply the organic-inorganic hybrid long-term anti-corrosion coating to the area to be coated, and obtain an organic-inorganic hybrid long-term anti-corrosion coating after drying; or, first pre-treat the area to be coated, then add high-temperature resistant fillers to the organic-inorganic hybrid long-term anti-corrosion coating to obtain a high-temperature resistant organic-inorganic hybrid long-term anti-corrosion coating, and then apply the high-temperature resistant organic-inorganic hybrid long-term anti-corrosion coating to the area to be coated, and obtain an organic-inorganic hybrid long-term anti-corrosion coating after drying.

[0076] The present invention has no special limitation on the specific operation of the pre-treatment. Adopting the pre-treatment method well-known to those skilled in the art can make the surface of the area to be coated flat and free of impurities.

[0077] In the present invention, the high-temperature resistant fillers preferably include nano-aluminum oxide (Al 2 O 3 ) and nano-zirconium oxide (ZrO 2); The mass of the nano-aluminum oxide is preferably 3-8% of the total mass of the organic-inorganic hybrid long-lasting anti-corrosion coating, more preferably 4-6%, and further preferably 5%; the mass of the nano-zirconium oxide is preferably 1-5% of the total mass of the organic-inorganic hybrid long-lasting anti-corrosion coating, more preferably 2-4%, and further preferably 3%; the addition of the high-temperature resistant filler is preferably carried out under stirring conditions. The present invention has no special limitations on the particle size and source of the nano-aluminum oxide and nano-zirconium oxide, and commercially available nano-aluminum oxide and nano-zirconium oxide well-known to those skilled in the art can be used as the coating filler. The present invention has no special limitations on the stirring rate and time, and it is sufficient to make the high-temperature resistant filler evenly mixed in the organic-inorganic hybrid long-lasting anti-corrosion coating. By adding the high-temperature resistant filler, the present invention can greatly improve the high-temperature resistance of the coating, enabling it to be applicable to a high-temperature environment of 1000 °C.

[0078] The present invention has no special limitations on the specific operation of the coating, and it is sufficient to make the organic-inorganic hybrid long-lasting anti-corrosion coating form a uniform-thickness organic-inorganic hybrid long-lasting anti-corrosion coating in the area to be coated.

[0079] The coating formed by using the organic-inorganic hybrid long-lasting anti-corrosion coating of the present invention can effectively resist various corrosion forms such as acid-base corrosion, electrochemical corrosion, and low-temperature corrosion, and can provide effective protection for more than 15 years in a harsh environment, greatly reducing the frequency of anti-corrosion operations in thermal power plants; at the same time, the coating process is simple and the cost is low, making the production process of the coating simple and easy to implement, and while reducing the frequency of coating maintenance and replacement, reducing the safety risk of high-altitude operations.

[0080] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0081] Example 1

[0082] A preparation method of an organic-inorganic hybrid long-lasting anti-corrosion coating is the following steps:

[0083] (1) Under stirring conditions, drop the silica sol into the polyetheramine, then heat to 60 °C and keep warm for 30 min. Stirring is continuously carried out during the heat preservation process. Then, after cooling to 40 °C, isophorone diisocyanate is slowly added, and stirring is continued for 60 min to obtain a nano-silica sol modified isocyanate prepolymer, which is sealed and stored; the molecular weight of the polyetheramine is 2000; the particle size of the silica sol is 20-50 nm; the mass ratio of the polyetheramine to the silica sol is 1:0.5; the mass ratio of the isophorone diisocyanate to the polyetheramine is 1:1;

[0084] (2) First, mix the terminal amino polyether and the amine chain extender and stir for 20 min, then add methyltrimethoxysilane under stirring conditions, and then stir for 20 min to obtain an organosilicon-modified amino polyether system, which is stored sealed; the molecular weight of the terminal amino polyether is 2000; the amine chain extender is amine chain extender E300; the mass ratio of the terminal amino polyether to the amine chain extender is 12:1; the mass ratio of the terminal amino polyether to methyltrimethoxysilane is 12:0.6;

[0085] (3) Under magnetic stirring conditions, drop the organosilicon-modified amino polyether system obtained in step (2) into the nano-silica sol-modified isocyanate prepolymer obtained in step (1), and carry out hydrolysis reaction and condensation reaction in sequence to obtain an organic-inorganic hybrid long-acting anti-corrosion coating; the mass ratio of the nano-silica sol-modified isocyanate prepolymer to the organosilicon-modified amino polyether system is 2:1; the temperature of the hydrolysis reaction is 60 °C, and the pH value of the hydrolysis reaction is 6; the temperature of the condensation reaction is 60 °C, and the time of the condensation reaction is 60 min.

[0086] Application Example 1

[0087] Boilers and the main steel frames of electrostatic precipitators are long-term exposed to high temperatures (500 - 800 °C), high humidity and corrosive gases (such as SO 2 and NO 3 ) environments, and the coating is required to have excellent high-temperature resistance, corrosion resistance and adhesion. Sandblast the surfaces of boilers and the main steel frames of electrostatic precipitators to remove rust and impurities, reaching a cleanliness level of Sa2.5. Use a high-pressure airless spraying device to evenly coat the organic-inorganic hybrid long-acting anti-corrosion coating prepared in Example 1 on the steel frame surface, with a coating thickness of 150 - 200 μm. The coating is air-dried naturally at room temperature for 12 h, then cured at 80 °C for 2 h, and finally heat-treated at 200 °C for 1 h to form a dense organic-inorganic hybrid long-acting anti-corrosion coating.

[0088] Test the high-temperature resistance, corrosion resistance, bonding property and abrasion resistance of the organic-inorganic hybrid long-acting anti-corrosion coating obtained in Application Example 1. The test methods and results are as follows: Continuously heat at 800 °C for 100 h, and the coating has no cracking, peeling or discoloration; Test in a simulated boiler flue gas environment (5% SO 2 , humidity 90%) for 1000 h, and the corrosion rate ≤ 0.01 mm / year; The bonding strength between the coating and the steel frame reaches 18 MPa (in accordance with the standard of GB / T5210-2006); Conduct a friction and wear test at 500 °C, and the wear amount ≤ 5%.

[0089] After testing, the organic-inorganic hybrid long-acting anti-corrosion coating obtained in Application Example 1 significantly improved the corrosion resistance, high-temperature resistance, and wear resistance of the boiler and the main steel frame of the electrostatic precipitator, and was able to effectively resist the erosion of the boiler and the main steel frame of the electrostatic precipitator in high-temperature, high-humidity, and highly corrosive environments, extending the service life of the boiler equipment.

[0090] Application Example 2

[0091] Underground pipelines are in a humid, soil-corrosive, and microbe-eroded environment for a long time, and the coating is required to have excellent water resistance, anti-microbial corrosion resistance, and soil stress resistance. The surface of the underground pipeline is sandblasted to reach a cleanliness level of Sa2.5. The organic-inorganic hybrid long-acting anti-corrosion coating prepared in Example 1 is evenly coated on the pipeline surface using a spraying device, and the coating thickness is 200 - 250 μm. The coating is naturally air-dried at room temperature for 12 h, and then cured at 60 °C for 4 h to form a dense organic-inorganic hybrid long-acting anti-corrosion coating.

[0092] The water resistance, anti-microbial corrosion resistance, and soil stress resistance of the organic-inorganic hybrid long-acting anti-corrosion coating obtained in Application Example 2 were tested. The test methods and results are as follows: Immersed in distilled water for 30 days, the coating showed no blistering or peeling, and the water absorption rate ≤ 1%; Anti-microbial corrosion resistance: Tested in a simulated soil environment (containing sulfate-reducing bacteria) for 90 days, and there were no microbial corrosion marks on the coating; In the soil stress test, the coating showed no cracking or peeling. The adhesion between the coating and the pipeline reached 15 MPa.

[0093] After testing, the organic-inorganic hybrid long-acting anti-corrosion coating obtained in Application Example 2 significantly improved the water resistance, anti-microbial corrosion resistance, and soil stress resistance of the underground pipeline, enabling it to work underground for a long time without being eroded, and extending the service life of the underground pipeline.

[0094] Example 2

[0095] A preparation method of an organic-inorganic hybrid long-acting anti-corrosion coating, which is the following steps:

[0096] (1) Under stirring conditions, silica sol is dropped into polyetheramine, and then heated to 65 °C and kept warm for 45 min. Stirring is continuously carried out during the heat preservation process. Then, after cooling to 40 °C, isophorone diisocyanate is slowly added, and stirring is continued for 70 min to obtain a nano-silica sol modified isocyanate prepolymer, which is sealed and stored; the molecular weight of the polyetheramine is 3000; the particle size of the silica sol is 10 - 20 nm; the mass ratio of the polyetheramine to the silica sol is 1:0.8; the mass ratio of the isophorone diisocyanate to the polyetheramine is 1:1.2;

[0097] (2) First, mix the amino-terminated polyether and the amine chain extender and stir for 20 min. Then, add methyltrimethoxysilane under stirring conditions, and then stir for another 20 min to obtain an organosilicon-modified amino polyether system, which is sealed and stored. The molecular weight of the amino-terminated polyether is 3000; the amine chain extender is amine chain extender E300; the mass ratio of the amino-terminated polyether to the amine chain extender is 13:1.5; the mass ratio of the amino-terminated polyether to methyltrimethoxysilane is 13:0.7;

[0098] (3) Under magnetic stirring conditions, drop the organosilicon-modified amino polyether system obtained in step (2) into the nano-silica sol-modified isocyanate prepolymer obtained in step (1), and carry out hydrolysis reaction and condensation reaction in sequence to obtain an organic-inorganic hybrid long-lasting anti-corrosion coating. The mass ratio of the nano-silica sol-modified isocyanate prepolymer to the organosilicon-modified amino polyether system is 2:1; the temperature of the hydrolysis reaction is 60 °C, and the pH value of the hydrolysis reaction is 6; the temperature of the condensation reaction is 60 °C, and the time of the condensation reaction is 60 min.

[0099] Application Example 3

[0100] The desulfurization absorption tower and its surrounding environment are long-term exposed to high humidity, strong acidity (pH = 2 - 4) and corrosive media (such as H 2 SO 4 and HCl), so the coating is required to have excellent acid corrosion resistance and damp heat resistance. Sandblasting treatment is carried out on the inner wall of the desulfurization absorption tower and the surrounding steel structures to reach a cleanliness level of Sa2.5. Use the brushing method to evenly coat the surface with the organic-inorganic hybrid long-lasting anti-corrosion coating prepared in Example 2, and the coating thickness is 200 - 250 μm. The coating is naturally air-dried at room temperature for 12 h, and then cured at 60 °C for 4 h to form a dense organic-inorganic hybrid long-lasting anti-corrosion coating.

[0101] Test the corrosion resistance, adhesion and abrasion resistance of the organic-inorganic hybrid long-lasting anti-corrosion coating obtained in Application Example 3. The test methods and results are as follows: Immerse in 10% H 2 SO 4 solution for 30 days, the coating has no blistering, peeling or discoloration, and the corrosion rate ≤ 0.01 mm / year; Test in an environment of 60 °C and 95% humidity for 1000 h, the coating has no blistering or peeling; The adhesion of the coating to the substrate reaches 16 MPa; Carry out friction and wear test at room temperature, and the wear amount ≤ 5%.

[0102] After detection, the organic-inorganic hybrid long-lasting anti-corrosion coating obtained in Application Example 3 significantly improves the corrosion resistance and abrasion resistance of the inner wall of the desulfurization absorption tower and the surrounding steel structures in the thermal power plant, and extends the service life of the inner wall of the desulfurization absorption tower and the surrounding steel structures.

[0103] Application Example 4

[0104] Outdoor pipelines are exposed to ultraviolet rays, rainwater, temperature changes, and atmospheric corrosion environments for a long time, so the coating is required to have excellent weather resistance, anti-ultraviolet, and temperature difference resistance. The surface of the outdoor pipeline is sandblasted to reach a cleanliness level of Sa2.5. The organic-inorganic hybrid long-term anti-corrosion coating prepared in Example 2 is evenly coated on the pipeline surface using a spraying device, and the coating thickness is 150 - 200 μm. The coating is naturally air-dried at room temperature for 12 h and then cured at 80 °C for 2 h to form a dense organic-inorganic hybrid long-term anti-corrosion coating.

[0105] The weather resistance, anti-ultraviolet, and temperature difference resistance of the organic-inorganic hybrid long-term anti-corrosion coating obtained in Application Example 3 are tested. The test methods and results are as follows: In the QUV accelerated aging test (UV irradiation + spray cycle), it is tested for 1000 h, and the coating shows no powdering, cracking, or discoloration; under ultraviolet irradiation, it is tested for 500 h, and the yellowing index ΔE of the coating ≤ 2; in the temperature cycle test from -40 °C to 80 °C, the coating shows no cracking or peeling; the adhesion between the coating and the pipeline reaches 17 MPa.

[0106] After testing, the organic-inorganic hybrid long-term anti-corrosion coating obtained in Application Example 4 significantly improves the weather resistance, anti-ultraviolet, and temperature difference resistance of outdoor pipelines and extends the service life of outdoor pipelines.

[0107] Comparative Example 1

[0108] A preparation method of a polyurea coating, which comprises the following steps:

[0109] (1) Polyetheramine (molecular weight 2000) and isophorone diisocyanate are mixed in a mass ratio of 1:1, heated to 60 °C, and stirred for 60 min to obtain a polyurea prepolymer;

[0110] (2) Terminal amino polyether (molecular weight 2000) and amine chain extender E300 are mixed in a mass ratio of 12:1 and stirred for 20 min to obtain an amino polyether system;

[0111] (3) The polyurea prepolymer obtained in step (1) and the amino polyether system obtained in step (2) are mixed in a mass ratio of 2:1, stirred and reacted to obtain a polyurea coating.

[0112] After testing, when heated at 800 °C for 1 hour, the coating is completely carbonized; when tested in a simulated boiler flue gas environment for 1000 hours, the corrosion rate is 0.5 mm / year; the adhesion between the coating and the steel frame is 5 MPa; when subjected to a friction and wear test at 500 °C, the wear amount is 50%.

[0113] Comparative Example 2

[0114] A preparation method of a coating, which comprises the following steps:

[0115] (1) Heat the polyetheramine (with a molecular weight of 2000) to 60 °C, stir for 30 min, then cool to 40 °C and slowly add isophorone diisocyanate, and continue stirring for 60 min to obtain an isocyanate prepolymer, which is sealed and stored;

[0116] (2) First, mix the amino-terminated polyether (with a molecular weight of 2000) and the amine chain extender E300 in a mass ratio of 12:1, stir for 20 min, then add methyltrimethoxysilane under stirring conditions, and then stir for 20 min to obtain an organosilicon-modified amino polyether system, which is sealed and stored;

[0117] (3) Mix the isocyanate prepolymer obtained in step (1) and the organosilicon-modified amino polyether system obtained in step (2) in a mass ratio of 2:1, stir and react to obtain a coating.

[0118] After testing, when heated at 800 °C for 10 hours, the coating cracked; when tested in a simulated boiler flue gas environment for 1000 hours, the corrosion rate was 0.5 mm / year; Adhesion: The bonding force between the coating and the steel frame was 8 MPa; When performing friction and wear tests at 500 °C, the wear amount was 20%.

[0119] Comparative Example 3

[0120] A method for preparing a coating, which is the following steps:

[0121] (1) Under stirring conditions, drop the silica sol into the polyetheramine, then heat to 60 °C and keep it warm for 30 min. Stirring is continuously carried out during the heat preservation process. Then cool to 40 °C and slowly add isophorone diisocyanate, and continue stirring for 60 min to obtain a nano-silica sol-modified isocyanate prepolymer, which is sealed and stored;

[0122] (2) Mix the amino-terminated polyether (with a molecular weight of 2000) and the amine chain extender E300 in a mass ratio of 12:1, stir for 20 min to obtain an amino polyether system, which is sealed and stored;

[0123] (3) Mix the nano-silica sol-modified isocyanate prepolymer obtained in step (1) and the amino polyether system obtained in step (2) in a mass ratio of 2:1, stir and react to obtain a coating.

[0124] After testing, when soaked in distilled water for 30 days, the coating foamed; when tested in a simulated soil environment for 90 days, microbial corrosion marks appeared on the coating; The bonding force between the coating and the pipeline was 7 MPa; When performing friction and wear tests at 500 °C, the wear amount was 25%.

[0125] Comparative Application Examples 1 - 3

[0126] The surfaces of the outdoor pipelines of three basically identical thermal power plants were respectively subjected to sandblasting treatment to remove rust and impurities, reaching a cleanliness level of Sa2.5. Then, the coatings prepared in Comparative Examples 1 to 3 were evenly coated on the surfaces of the outdoor pipelines of the thermal power plants using a high-pressure airless spraying device, with a coating thickness of 150 - 200 μm. The coatings were naturally air-dried at room temperature for 12 h and then cured at 80 °C for 2 h to form a dense anti-corrosion coating, which were respectively denoted as Comparative Application Examples 1 to 3 in sequence.

[0127] The performances of the coatings obtained from Application Example 1, 3 and Comparative Application Examples 1 to 3 were tested, and the results are shown in Table 1. Through the systematic comparison between the examples and the comparative examples, the present invention is significantly superior to the conventional polyurea coatings and the coatings omitting key components in terms of high temperature resistance, corrosion resistance, adhesion and abrasion resistance, fully reflecting its technical advantages and application value.

[0128] Table 1 Performance comparison of the coatings obtained from Application Example 1, 3 and Comparative Application Examples 1 to 3

[0129]

[0130]

[0131] The specific test methods and evaluation criteria are as follows:

[0132] 1. Corrosion resistance

[0133] Test method:

[0134] According to "GB / T 1771-2007 Determination of resistance to neutral salt spray of paints and varnishes", the coating specimens were placed in a simulated boiler flue gas environment (5% SO 2 , humidity 90%) for testing for 1000 h.

[0135] The corrosion rate was calculated by the weight loss method:

[0136]

[0137] Among them, ΔW is the mass loss of the specimen (g), A is the surface area (cm 2 ), t is the time (h), and ρ is the metal density (g / cm 3 ).

[0138] Evaluation criteria:

[0139] Excellent - corrosion rate ≤ 0.01 mm / year (no visible corrosion points on the coating surface, no blistering at the edges);

[0140] General - corrosion rate 0.1 - 0.5 mm / year (local corrosion or slight blistering appears on the surface);

[0141] Poor - corrosion rate ≥ 0.5 mm / year (large - area peeling of the coating or obvious corrosion of the substrate).

[0142] 2. High - temperature resistance

[0143] Test method:

[0144] According to the "ASTM E119 Standard Test Method for Fire Tests of Building Construction and Materials", place the coating specimen in a high - temperature furnace and heat it at a rate of 10 °C / min to 800 °C, and hold it at this temperature for a specified time (100 h for the example, and record the actual tolerance time for the comparative example). Observe the surface morphology of the coating (cracking, peeling, and discoloration) and record the failure time.

[0145] Evaluation criteria:

[0146] Excellent - continuously heated at 800 °C for 100 h, the coating has no cracking, peeling, or discoloration;

[0147] General - the coating carbonizes or peels within 1 h of heating at 800 °C;

[0148] Poor - obvious cracking or peeling of the coating occurs within 10 h of heating at 800 °C.

[0149] 3. Abrasion resistance

[0150] Test method:

[0151] According to the "ASTM G133 Standard Test Method for Linear Reciprocating Friction and Wear", use a friction testing machine (load 10 N, frequency 2 Hz, friction pair is a tungsten carbide ball) to test the wear resistance of the coating at high temperature (500 °C).

[0152] Wear amount calculation formula:

[0153] Wear amount (%)=(initial thickness - thickness after wear)*100% / initial thickness

[0154] Evaluation criteria:

[0155] Excellent - wear amount ≤ 5% (no obvious scratches on the coating surface);

[0156] General - wear amount 20% - 50% (visible scratches on the surface, but the substrate is not exposed);

[0157] Poor - wear amount ≥ 50% (part or all of the substrate is exposed).

[0158] As can be seen from Table 1, the organic-inorganic hybrid long-acting anti-corrosion coating provided by the present invention is significantly superior to conventional polyurea materials in terms of corrosion resistance, high-temperature resistance, and abrasion resistance. At the same time, through the comparison of Application Examples 1 and 3 and Comparative Application Examples 2 to 3, it can be seen that when silica sol or methyltrimethoxysilane is omitted, the corrosion resistance, high-temperature resistance, and abrasion resistance of the formed coating all show a significant decrease, and even lower than that of conventional polyurea materials. This shows that by optimizing the composition of the coating, the present invention can significantly improve its corrosion resistance, high-temperature resistance, and abrasion resistance, making the organic-inorganic hybrid long-acting anti-corrosion coating particularly suitable for high-temperature, high-humidity, and highly corrosive environments inside the boiler furnace.

[0159] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing an organic-inorganic hybrid long-lasting anticorrosive coating, characterized in that: The following steps are involved: (1) mixing polyetheramine, silica sol and isophorone diisocyanate to obtain a nano-silica sol-modified isocyanate prepolymer; (2) mixing the amino-terminated polyether, an amine chain extender and methyltrimethoxysilane to obtain an organosilicon-modified amino-polyether system; (3) mixing the nano-silica sol-modified isocyanate prepolymer obtained in step (1) and the organosilicon-modified amino polyether system obtained in step (2), and sequentially subjecting the mixture to hydrolysis reaction and condensation reaction to obtain an organic-inorganic hybrid long-lasting anticorrosive coating; The steps (1) and (2) are performed in no particular order.

2. The preparation method according to claim 1, characterized in that: In the step (1), the molecular weight of the polyetheramine is 2000-4000, and the particle size of the silica sol is 10-100 nm.

3. The preparation method according to claim 1, characterized in that: The mass ratio of the polyetheramine to the silica sol in the step (1) is 1:(0.1-1).

4. The preparation method according to claim 1, characterized in that: In the step (1), the mass ratio of isophorone diisocyanate to polyetheramine is 1:(1-1.5).

5. The preparation method according to claim 1, characterized in that: In the step (2), the mass ratio of the terminal amino polyether to the amine chain extender is (8-20): (1-2).

6. The preparation method according to claim 1, characterized in that: In the step (2), the mass ratio of the terminal amino polyether to methyltrimethoxysilane is (8-20): (0.5-1).

7. The preparation method according to claim 1, characterized in that: In the step (3), the mass ratio of the nano-silica sol-modified isocyanate prepolymer to the organosilicon-modified amino polyether system is (1-3):

1.

8. The preparation method according to claim 1, characterized in that: In the step (3), the temperature of the hydrolysis reaction is 40-60° C., and the pH value of the hydrolysis reaction is 4-6; the temperature of the condensation reaction is 60-80° C., and the time of the condensation reaction is 60-90 minutes.

9. The organic-inorganic hybrid long-lasting anticorrosive coating prepared by the preparation method according to any one of claims 1 to 8.

10. The use of the organic-inorganic hybrid long-term anticorrosion coating according to claim 9 in metal facilities of thermal power plants, characterized in that: The metal facilities of the thermal power plant include the boiler furnace, the main steel frame of the electrostatic precipitator, the desulfurization absorption tower and the surrounding corrosive environment, underground pipelines and outdoor pipelines.

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