A composite crosslinking network rust conversion coating and its preparation method and application

Abstract

The application discloses a composite crosslinking network rust conversion coating and a preparation method and application thereof. The rust conversion coating prepared by the application fully plays a barrier, corrosion inhibition and passivation effect, effectively prolongs diffusion paths of corrosion media such as water, oxygen and NaCl, and has excellent corrosion resistance. Organic components in the coating penetrate into the inside of a substrate through a rust layer and are consolidated, so that the adhesion of the coating is greatly improved. The preparation method of the composite crosslinking network rust conversion coating is simple in operation, low in cost and universal, and can be applied to the preparation of a corrosion-resistant coating of a rust-bearing substrate in an engineering material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of anticorrosive coatings, and particularly relates to a composite crosslinking network rust conversion coating and a preparation method and application thereof. BACKGROUND

[0002] With the development of marine anticorrosion technology, the performance and surface pretreatment of protective coatings for different coating areas of offshore oil platforms are required to be refined and strict. According to ISO 12944-2019 and HG / T5059-2016, the surface rust removal requirement of the exposed atmospheric area is at least Sa2 level, that is, almost all oxides, rust and contaminants should be removed, and the residues are firmly attached. Rust has a loose and porous structure, which hinders the direct contact between the primer and the metal substrate, and weakens the adhesion between the primer and the substrate. In addition, the corrosion products contain water, NaCl and other corrosion media, which further accelerate the corrosion progress of the metal substrate. Although mechanical rust removal techniques such as sandblasting and grinding have been widely used, there are still some special engineering fields that are not convenient for rust removal, such as oil drilling platforms equipped with storage tanks and chemical pipeline systems. Mechanical rust removal methods are prone to safety hazards such as static electricity and sparks. Therefore, it is necessary to prepare a rusted coating that can be directly applied to the rusted substrate.

[0003] Rust conversion coating is a new anticorrosive coating technology that has achieved some industrial applications. For example, RUST-X water-based primer is a rust-preventive product that is brushed or sprayed on a rusted metal substrate, which is made of acid and chemicals. Among them, the acid reacts with rust to convert the rust into a stable complex, thereby enhancing the interfacial adhesion between the primer and the substrate. However, excessive acid accelerates the corrosion degree of the metal substrate, greatly increasing the difficulty of construction. At present, most of the rusted anticorrosive coatings applied in the market still have problems such as insufficient adhesion and poor corrosion resistance. Therefore, it is urgent to develop a simple and efficient, high-universal composite crosslinking network rust conversion coating preparation method. SUMMARY

[0004] In order to overcome the deficiencies and shortcomings of the prior art, the primary purpose of the present application is to provide a preparation method of a composite crosslinking network rust conversion coating. The preparation method of the composite crosslinking network rust conversion coating is simple to operate, low in cost and has universality.

[0005] The second purpose of the present application is to provide a composite crosslinking network rust conversion coating prepared by the above preparation method. The rust conversion coating prepared by the present application fully plays the roles of barrier, corrosion inhibition and passivation, effectively prolongs the diffusion path of corrosion media such as water, oxygen and NaCl, and has excellent corrosion resistance. The organic components in the coating penetrate into the interior of the substrate through the rust layer and are consolidated, and the adhesion of the coating is greatly improved. The present preparation method can be applied to the preparation of rusted substrate anticorrosive coatings in engineering materials.

[0006] A third object of the present application is to provide an application of the composite cross-linked network rust conversion coating.

[0007] The primary object of the present application is achieved by the following technical solutions:

[0008] A preparation method of a composite cross-linked network rust conversion coating, comprising the following preparation steps:

[0009] (1) Preparation of polyurea prepolymer: A component and B component are configured according to 2-5:1, the A component is added into the B component under a nitrogen environment, stirred uniformly, and heated to react to prepare a polyurea prepolymer;

[0010] (2) Preparation of functional MOF filler: A' component and B' component are configured according to 1:1, vacuum dried to obtain a functional MOF material (3D MOF material);

[0011] (3) The prepared polyurea prepolymer, reactive diluent, functional MOF filler, rate modifier, and auxiliary agent are configured according to weight fractions 30-50:30-50:20-40:30-50:2-5, mixed and stirred at room temperature to be coated on a rusted substrate to prepare a composite cross-linked network rust conversion coating;

[0012] The A component is at least one of PAPI, MDI, LMDI, TDI, XDI, H6XDI, TMXDI, IPDI, and HDI;

[0013] The B component is one or more of T-5000, T-3000, T-403, D-4000, D-2000, D-400, and D-230;

[0014] The A' component is one or more of aluminum powder, zinc powder, and aluminum silver paste;

[0015] The B' component is a methanol solution of at least one of zinc nitrate hexahydrate, zinc phosphate, zinc chromate, and aluminum dihydrogen phosphate mixed with 2-methyl imidazole, stirred at room temperature by one-pot method reaction, centrifuged to collect white precipitate, which is the B' component.

[0016] Preferably, the stirring time in step (1) is 0.5-1h, and the heating temperature is 70-80℃.

[0017] Preferably, the vacuum drying temperature in step (2) is 50-70℃.

[0018] Preferably, the reactive diluent in step (3) is at least one of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate.

[0019] Preferably, the rate regulator in step (3) is prepared by the following preparation method:

[0020] a. Synthesis of amino-terminated hyperbranched siloxane: under inert environment, amino-containing siloxane, water and ethanol are mixed in a mass ratio of 100:(10-30):150, stirred at 60-80℃ for 6-8h, and then the solvent is removed by rotary evaporation to obtain the amino-terminated hyperbranched siloxane;

[0021] b. Synthesis of rate regulator: isobutyraldehyde and amino-terminated hyperbranched siloxane are prepared in a mass ratio of 1:1, and the amino-terminated hyperbranched siloxane is added into the isobutyraldehyde under room temperature and inert gas environment and stirred for 5min; after stirring is completed, the temperature is raised to 120℃, and water separation is performed by water separator; after 10-12h of reaction, the reaction is terminated, and then excess isobutyraldehyde and water are removed by distillation under reduced pressure to obtain the rate regulator (closed amino-terminated hyperbranched siloxane).

[0022] Preferably, the amino group in the amino-containing siloxane in step a refers to one of methylamino, ethylamino, propylamino, butylamino, pentylamino, hexylamino, heptylamino and octylamino.

[0023] Preferably, the auxiliary agent in step (3) is a dispersing agent, a rheological agent, an anti-settling agent, a leveling agent and a defoaming agent.

[0024] Preferably, the dispersing agent is at least one of BYK-108, BYK-110, BYK-116, BYK-163, BYK-180, BYK-190 and BYK-9076;

[0025] The rheological agent is at least one of organic bentonite, hydrogenated castor oil and fumed silica;

[0026] The anti-settling agent comprises one or more of polyethylene wax, oxidized polyethylene and polyamide wax;

[0027] The leveling agent comprises one or more of silicone, polyacrylate and cellulose acetate butyrate;

[0028] The defoaming agent comprises one or more of mineral oil, tributyl phosphate and silicone resin.

[0029] The second object of the present application is achieved by the following technical scheme:

[0030] A composite crosslinking network rust conversion coating prepared by the above preparation method.

[0031] The third object of the present application is achieved by the following technical scheme:

[0032] Application of a composite crosslinking network rust conversion coating in the field of rusted substrate corrosion protection.

[0033] Compared with the prior art, the method has the following advantages and effects:

[0034] (1) The conventional rust conversion coating cannot fully play a barrier role on the rusted surface, resulting in that water, oxygen, NaCl and other corrosion media easily penetrate the coating to reach the metal substrate surface; in the composite crosslinking network rust conversion coating, the reaction-type diluent and the rate regulator synergistically reduce the viscosity of the organic resin, promote the coating to quickly penetrate deep into the rust, wrap and divide the rust, make the rust lose activity, and improve the adhesion of the coating.

[0035] (2) The composite crosslinking network rust conversion coating can quickly capture water molecules and react with the water molecules, inhibit the reaction of NCO with water, and avoid the formation of bubbles.

[0036] (3) The composite crosslinking network rust conversion coating, the reaction-type diluent is a carbonate solvent, which effectively reduces the viscosity of the system, forms beta-hydroxy carbonate with the unblocked rate regulator, and produces a chemical bond between the polyurea molecules. Therefore, unlike other added diluents, it does not migrate with the extension of the service life, ensuring the stability and durability of the material. The composite crosslinking network rust conversion coating, the reaction-type diluent is a carbonate solvent, which effectively reduces the viscosity of the system, forms beta-hydroxy carbonate with the unblocked rate regulator, and produces a chemical bond between the polyurea molecules, ensuring the stability and durability of the material. In addition, the carbonate solvent is a green and environmentally friendly solvent with high boiling point and low VOC characteristics, which does not migrate with the extension of the service life like other added diluents, and does not pollute the environment.

[0037] (4)The polyurea prepolymer, the reactive diluent, the functional MOF filler, the rate modifier and the auxiliary agent prepared are mixed and stirred at room temperature according to weight parts 30-50: 30-50: 20-40: 30-50: 2-5 to prepare a coating, which is coated on a rusted substrate; the rust is wrapped and divided by downward penetration of the organic components, the rust is inhibited and passivated by the functional MOF filler, and a dense crosslinked coating with excellent corrosion resistance and high adhesion is formed after curing. The composite crosslinked network rust conversion coating described in the application strictly requires the ratio of the functional MOF filler A component and the B component, the A component forms a dense oxide protective film on the surface of the coating, which improves the mechanical properties and corrosion resistance of the coating; the B component slowly releases zinc phosphate and other corrosion inhibitors through the 3D MOF structure to react with iron rust to form a complex, further inhibiting the occurrence of corrosion, and imparting the coating with the functions of barrier, corrosion inhibition and passivation. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 Synthesis route of the amino-terminated hyperbranched siloxane;

[0039] Figure 2 Synthesis route of the rate modifier;

[0040] Figure 3 Different amino structural formulas;

[0041] Figure 4 It is the penetration mechanism diagram of example 1 on the rusted substrate;

[0042] Figure 5 It is the electrochemical impedance spectroscopy diagram of example 2 and comparative example 2 immersed in 3.5wt% NaCl solution for different times;

[0043] Figure 6 It is the surface condition of example 2 and comparative example 2 in 5wt% NaCl neutral salt spray before and after 2000h. DETAILED DESCRIPTION

[0044] The application will be further described in detail below in conjunction with specific examples, but the embodiments of the application are not limited thereto. The materials used in the examples of the application can be purchased by marketable means.

[0045] The specific conditions not specified in the examples of the application are carried out according to conventional conditions or the conditions recommended by the manufacturer. The raw materials, reagents and the like not specified by the manufacturer are all conventional products that can be purchased by marketable means. The parts in the following examples refer to weight parts.

[0046] Example 1

[0047] 10 parts by weight of PAPI, 10 parts by weight of MDI were added into a three-necked flask with magnetic stirring, and 10 parts by weight of D-230 was slowly dropped into the three-necked flask at 45°C using a dropping funnel, stirred for 0.5 hours, then warmed to 70-80°C and continued to react for 4 hours, and the polyurea prepolymer was obtained after full reaction; 30 parts by weight of methylamino-terminated hyperbranched siloxane, 30 parts by weight of ethylamino-terminated hyperbranched siloxane were dropped into a three-necked flask with magnetic stirring containing 60 parts by weight of isobutyraldehyde, warmed to 120°C under stirring and nitrogen atmosphere, and continued to react for 10 hours, while a water trap was used to remove the water generated in the reaction, then excess isobutyraldehyde and water were removed by distillation under reduced pressure, and the rate regulator was obtained. 30 parts by weight of the polyurea prepolymer was taken out and added to a sealed stirring tank, then 10 parts by weight of ethylene carbonate, 20 parts by weight of propylene carbonate, 30 parts by weight of the rate regulator, 10 parts by weight of aluminum powder, 10 parts by weight of zinc phosphate 3D MOF material, 0.4 parts by weight of BYK-108, 0.4 parts by weight of organic bentonite, 0.4 parts by weight of polyethylene wax, 0.4 parts by weight of silicone, and 0.4 parts by weight of mineral oil were added, and mixed and stirred uniformly at room temperature using a high-speed disperser at 400 r / min to obtain a composite cross-linked network rust conversion coating material, and the obtained material was coated on rusted steel plates and tinplate.

[0048] Example 2

[0049] 25 parts by weight of LMDI, 25 parts by weight of TDI were added into a three-necked flask with magnetic stirring, and 10 parts by weight of D-400 was slowly dropped into the three-necked flask at 45°C using a dropping funnel, stirred for 0.5 hours, then warmed to 70-80°C and continued to react for 4 hours, and the polyurea prepolymer was obtained after full reaction; 30 parts by weight of propylamino-terminated hyperbranched siloxane, 30 parts by weight of butylamino-terminated hyperbranched siloxane were dropped into a three-necked flask with magnetic stirring containing 60 parts by weight of isobutyraldehyde, warmed to 120°C under stirring and nitrogen atmosphere, and continued to react for 10 hours, while a water trap was used to remove the water generated in the reaction, then excess isobutyraldehyde and water were removed by distillation under reduced pressure, and the rate regulator was obtained. 50 parts by weight of the polyurea prepolymer was taken out and added to a sealed stirring tank, then 30 parts by weight of butylene carbonate, 20 parts by weight of propylene carbonate, 50 parts by weight of the rate regulator, 20 parts by weight of zinc powder, 20 parts by weight of zinc chromate 3D MOF material, 1 part by weight of BYK-110, 1 part by weight of hydrogenated castor oil, 1 part by weight of oxidized polyethylene, 1 part by weight of polyacrylate, and 1 part by weight of tributyl phosphate were added, and mixed and stirred uniformly at room temperature using a high-speed disperser at 400 r / min to obtain a composite cross-linked network rust conversion coating material, and the obtained material was coated on rusted steel plates and tinplate.

[0050] Example 3

[0051] 15 parts by weight of XDI, 15 parts by weight of H6XDI were added into a three-necked flask with magnetic stirring, nitrogen was filled, 5 parts by weight of D-2000, 5 parts by weight of D-4000, 5 parts by weight of T-403 were slowly dropped into the three-necked flask at 45℃ by using a dropping funnel, stirring for 0.5 hours, then the temperature was raised to 70-80℃ and the reaction was continued for 4 hours, and a polyurea prepolymer was obtained by full reaction; 30 parts by weight of pentylamino-terminated hyperbranched siloxane and 30 parts by weight of hexylamino-terminated hyperbranched siloxane were added into a three-necked flask with magnetic stirring under nitrogen atmosphere, the temperature was raised to 120℃, and the reaction was continued for 10 hours while using a water trap to remove the water generated in the reaction, then excess isobutyraldehyde and water were removed by distillation under reduced pressure to obtain a rate regulator. 30 parts by weight of the polyurea prepolymer was taken out and added into a sealed stirring tank, then 10 parts by weight of dimethyl carbonate, 20 parts by weight of diethyl carbonate, 30 parts by weight of the rate regulator, 15 parts by weight of aluminum silver paste, 15 parts by weight of zinc borate 3D MOF material, 0.4 parts by weight of BYK-116, 0.4 parts by weight of BYK-163, 0.4 parts by weight of fumed silica, 0.4 parts by weight of polyamide wax, 0.4 parts by weight of silicone, 0.4 parts by weight of mineral oil were added, and the mixture was uniformly stirred at room temperature by using a high-speed disperser at 400 r / min to obtain a composite cross-linked network rust conversion coating material. The obtained material was coated on rusted steel plates and tinplate.

[0052] Example 4

[0053] Into a three-necked flask with magnetic stirrer, 18 parts by weight of TMXDI and 18 parts by weight of IPDI were added, and then 5 parts by weight of T-5000 and 5 parts by weight of T-3000 were slowly dropped into the flask at 45°C using a dropping funnel, and stirred for 0.5 hours, and then the temperature was raised to 70-80°C for further reaction for 4 hours, to obtain a polyurea prepolymer. Into a three-necked flask with magnetic stirrer, 30 parts by weight of heptylamine-terminated hyperbranched siloxane and 30 parts by weight of octylamine-terminated hyperbranched siloxane were added, and then the temperature was raised to 120°C under stirring and nitrogen atmosphere, and reacted for 10 hours, while a water trap was used to remove the water generated in the reaction, and then excess isobutyraldehyde and water were removed by distillation under reduced pressure, to obtain a rate regulator. 30 parts by weight of the polyurea prepolymer was taken out and added into a sealed stirring tank, and then 10 parts by weight of methyl ethyl carbonate, 20 parts by weight of propylene carbonate, 30 parts by weight of the rate regulator, 15 parts by weight of aluminum silver paste, 15 parts by weight of aluminum dihydrogen phosphate 3D MOF material, 0.4 parts by weight of BYK-180, 0.4 parts by weight of BYK-190, 0.4 parts by weight of BYK-9076, 0.4 parts by weight of organic bentonite, 0.4 parts by weight of polyethylene wax, 0.4 parts by weight of polyacrylate, 0.4 parts by weight of mineral oil, 0.4 parts by weight of tributyl phosphate, and 0.4 parts by weight of silicone resin were added, and then mixed and stirred uniformly at room temperature using a high-speed disperser at 400 r / min, to obtain a composite crosslinked network rust conversion coating material. The obtained material was coated on rusted steel plates and tinplate.

[0054] Example 5

[0055] Into a three-necked flask with magnetic stirrer, 10 parts by weight of XDI, 10 parts by weight of IPDI, 10 parts by weight of HDI were added, and then 5 parts by weight of T-5000 and 5 parts by weight of D-2000 were slowly dropped into the flask at 45°C using a dropping funnel, and stirred for 0.5 hours, and then the temperature was raised to 70-80°C for further reaction for 4 hours, to obtain a polyurea prepolymer. Into a three-necked flask with magnetic stirrer, 30 parts by weight of ethylamino-terminated hyperbranched siloxane and 30 parts by weight of octylamino-terminated hyperbranched siloxane were added, and then the temperature was raised to 120°C under stirring and nitrogen atmosphere, and further reacted for 10 hours, while using a water trap to remove the water generated in the reaction, and then excess isobutyraldehyde and water were removed by distillation under reduced pressure, to obtain a rate regulator. 30 parts by weight of the polyurea prepolymer was taken out and added into a sealed stirring tank, and then 10 parts by weight of methyl ethyl carbonate, 20 parts by weight of propylene carbonate, 30 parts by weight of the rate regulator, 10 parts by weight of aluminum powder, 10 parts by weight of zinc phosphate 3D MOF material, 0.4 parts by weight of BYK-180, 0.4 parts by weight of BYK-190, 0.4 parts by weight of BYK-9076, 0.4 parts by weight of organic bentonite, 0.4 parts by weight of polyethylene wax, 0.4 parts by weight of polyacrylate, 0.4 parts by weight of mineral oil, and 0.6 parts by weight of tributyl phosphate were added, and then mixed and stirred uniformly at room temperature using a high-speed disperser at 400 r / min, to obtain a composite crosslinked network rust conversion coating material. The obtained material was coated on rusted steel plates and tinplate.

[0056] Comparative Example 1

[0057] Into a three-necked flask with magnetic stirrer, 10 parts by weight of PAPI and 10 parts by weight of MDI were added, and then 10 parts by weight of D-230 was slowly dropped into the flask at 45°C using a dropping funnel, and stirred for 0.5 hours, and then the temperature was raised to 70-80°C for further reaction for 4 hours, to obtain a polyurea prepolymer. 30 parts by weight of the polyurea prepolymer was taken out and added into a sealed stirring tank, and then 10 parts by weight of ethylene carbonate, 20 parts by weight of propylene carbonate, 10 parts by weight of aluminum powder, 10 parts by weight of zinc phosphate 3D MOF material, 0.4 parts by weight of BYK-108, 0.4 parts by weight of organic bentonite, 0.4 parts by weight of polyethylene wax, 0.4 parts by weight of organosilicon, and 0.4 parts by weight of mineral oil were added, and then mixed and stirred uniformly at room temperature using a high-speed disperser at 400 r / min, to obtain a composite crosslinked network rust conversion coating material. The obtained material was coated on rusted steel plates and tinplate.

[0058] Comparative Example 2

[0059] Into a three-necked flask with magnetic stirrer, 25 parts by weight of LMDI and 25 parts by weight of TDI were added, and then 10 parts by weight of D-400 was slowly dropped into the flask at 45℃ using a dropping funnel, and stirred for 0.5 hours, and then the temperature was raised to 70-80℃, and the reaction was continued for 4 hours to obtain a polyurea prepolymer. Into a three-necked flask with magnetic stirrer, 30 parts by weight of propylamino-terminated hyperbranched siloxane and 30 parts by weight of butylamino-terminated hyperbranched siloxane were added, and then the temperature was raised to 120℃ under stirring and nitrogen atmosphere, and the reaction was continued for 10 hours, and then a water trap was used to remove the water generated in the reaction, and then excess isobutyraldehyde and water were removed by distillation under reduced pressure to obtain a rate regulator. 50 parts by weight of the polyurea prepolymer was taken out and added into a sealed stirring tank, and then 30 parts by weight of butylene carbonate, 20 parts by weight of propylene carbonate, 50 parts by weight of the rate regulator, 1 part by weight of BYK-110, 1 part by weight of hydrogenated castor oil, 1 part by weight of oxidized polyethylene, 1 part by weight of polyacrylate, and 1 part by weight of tributyl phosphate were added, and then the mixture was uniformly stirred at room temperature using a high-speed disperser at 400 r / min to obtain a composite cross-linked network rust conversion coating material, and then the obtained material was coated on rusted steel plates and tinplate.

[0060] (1) The viscosity of the coating was tested using an NDJ-5S rotary viscometer at 25℃;

[0061] (2) The coating dry time was tested according to GB / T 1728-1979;

[0062] (3) The coating adhesion was tested according to GB / T 5210-2006;

[0063] (4) The coating salt spray resistance was tested according to GB / T 1765-1979.

[0064]

[0065] As can be seen from the comparison of Examples 1-5 and Comparative Examples 1-2, the coating prepared by adding the rate regulator has lower viscosity, shorter dry time, higher adhesion, and better corrosion resistance, and the coating without the rate regulator has higher viscosity, lower adhesion, and the coating will fall off after 2000 hours of salt spray; the coating with the functional MOF filler has higher adhesion and better corrosion resistance than the coating without the functional MOF filler, because the functional MOF filler can react with the rust on the substrate to form a stable complex, slow down the further expansion of the corrosion, and the coating has better corrosion resistance.

[0066] The above embodiments are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above embodiments, and any changes, modifications, substitutions, combinations, simplifications, etc. made without departing from the spirit and principles of the present application should be equivalent replacement manners and should be included in the protection scope of the present application.

Claims

1. A method of preparing a composite cross-linked network rust conversion coating, characterized in that, The preparation steps include: (1) Preparation of polyurea prepolymer: A component and B component are configured according to 2-5:1, A component is added into B component under nitrogen environment, stirring is uniformly carried out, and heating reaction is carried out, so that polyurea prepolymer is prepared; (2) Preparation of functional MOF filler: A' component and B' component are configured according to 1:1, and functional MOF material is obtained through vacuum drying; (3) The polyurea prepolymer, the reactive diluent, the functional MOF filler, the rate regulator and the auxiliary agent prepared in the preparation steps are configured according to weight fractions 30-50:30-50:20-40:30-50:2-5, mixed and stirred at room temperature, and coated on a rusted base material, so that a composite crosslinked network rust conversion coating is prepared; The A component is at least one of PAPI, MDI, LMDI, TDI, XDI, H6XDI, TMXDI, IPDI and HDI; The B component is one or more of T-5000, T-3000, T-403, D-4000, D-2000, D-400 and D-230; The A' component is one or more of aluminum powder, zinc powder and aluminum silver paste; The B' component is a methanol solution of at least one of zinc phosphate, zinc chromate, zinc borate and aluminum dihydrogen phosphate by mixing zinc nitrate hexahydrate and 2-methyl imidazole, and the white precipitate collected through centrifugal separation after one-pot reaction stirring at room temperature is the B' component; The rate regulator in step (3) is prepared by the following preparation method: a. Synthesis of amino-terminated hyperbranched siloxane: under inert environment, amino-containing siloxane, water and ethanol are mixed according to a mass ratio of 100:(10-30):150, stirring is carried out at 60-80℃ for 6-8 h, and the solvent is removed by rotary evaporation to obtain amino-terminated hyperbranched siloxane; b. Synthesis of rate regulator: isobutyraldehyde and amino-terminated hyperbranched siloxane are configured according to a mass fraction of 1:1, the amino-terminated hyperbranched siloxane is added into isobutyraldehyde under inert gas environment at room temperature and stirred for 5 min; after stirring is completed, the temperature is raised to 120℃, and water separation is carried out with a water trap; after reaction for 10-12 h, the reaction is terminated, and then excess isobutyraldehyde and water are removed by distillation under reduced pressure to obtain the rate regulator.

2. The method of claim 1, wherein the composite crosslinked network rust conversion coating is prepared by the steps of: The stirring time in step (1) is 0.5-1 h, and the heating temperature is 70-80℃.

3. The method of claim 1, wherein the composite crosslinked network rust conversion coating is prepared by the steps of: The vacuum drying temperature in step (2) is 50-70℃.

4. The method of claim 1, wherein the composite crosslinked network rust conversion coating is prepared by the steps of: The reactive diluent in step (3) is at least one of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate and methyl ethyl carbonate.

5. The method of claim 1, wherein the composite crosslinked network rust conversion coating is prepared by the steps of: The amino group in the amino-containing siloxane in step a refers to one of methylamino, ethylamino, propylamino, butylamino, pentylamino, hexylamino, heptylamino and octylamino.

6. The method of claim 1, wherein the composite crosslinked network rust conversion coating is prepared by the steps of: The auxiliary agent in step (3) is a dispersing agent, a rheological agent, an anti-settling agent, a leveling agent and a defoaming agent.

7. The method for preparing the composite cross-linked network corrosion conversion coating according to claim 6, characterized in that, The dispersing agent is at least one of BYK-108, BYK-110, BYK-116, BYK-163, BYK-180, BYK-190 and BYK-9076; The rheological agent is at least one of organic bentonite, hydrogenated castor oil, fumed silica; The anti-settling agent includes one or more of polyethylene wax, oxidized polyethylene, polyamide wax; The leveling agent includes one or more of silicone, polyacrylate, cellulose acetate butyrate; The defoaming agent includes one or more of mineral oil, tributyl phosphate, silicone resin.

8. A composite crosslinked network rust conversion coating characterized by, Prepared according to the preparation method of any one of claims 1 to 7.

9. Application of the composite crosslinked network rust conversion coating according to claim 8 in the field of corrosion protection of rusted substrates.

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