Preparation method of modified organic silicon resin, heavy anti-corrosion powder coating as well as preparation method and application of heavy anti-corrosion powder coating

Abstract

The invention provides a preparation method of modified organic silicon resin, a heavy-duty anti-corrosion powder coating and a preparation method and application of the heavy-duty anti-corrosion powder coating, and relates to the technical field of functional coatings. The prepared modified organic silicon resin is special organic silicon resin capable of being cured by dicyandiamide and is compounded with epoxy resin and linear novolac epoxy resin to serve as a main film forming substance of the coating, modified dicyandiamide is adopted as a curing agent, and the acid boiling resistance and the high temperature resistance of the epoxy powder coating can be greatly improved; and the long-acting protection performance of the epoxy powder coating under high-temperature and high-pressure extreme working conditions is obviously improved. The invention provides a heavy anti-corrosion powder coating which is a wear-resistant and anti-corrosion integrated coating with excellent interface bonding performance, and is particularly suitable for long-acting protection of oil field pipelines under high-temperature, high-pressure and strong-corrosion working conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of functional coatings, and particularly relates to a preparation method of a modified silicone resin, a heavy-duty anti-corrosion powder coating, and a preparation method and application thereof. Background Art

[0002] The anti-corrosion of downhole oil pipes in oil and gas fields plays a crucial role in the petroleum industry, which can extend the service life of the oil pipes, improve production efficiency, and ensure the safe transportation of oil and gas.

[0003] Epoxy powder coatings are one of the most commonly used anti-corrosion materials for oil pipes. Traditional epoxy powder coatings are usually prepared by using one or several combinations of epoxy resin, polyester resin, acrylic resin, and phenolic resin, and adding pigments, fillers, and functional additives. However, traditional epoxy powder coatings are prone to the "coating blistering - medium penetration - interface peeling" failure chain under the high-temperature and high-pressure dynamic working conditions in oil fields. Especially for deep well oilfield pipelines (including oil pipes, sucker rods, etc.) with a well depth of more than 5000 meters, the working conditions are as follows: temperature 150 - 220 °C, pressure 15 - 50 MPa, and coexisting corrosion media of H2S / CO2, and the conditions are more severe. Traditional epoxy powder coatings are difficult to meet the long-term protection performance under extreme working conditions. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a preparation method of a modified silicone resin, a heavy-duty anti-corrosion powder coating, and a preparation method and application thereof. The modified silicone resin prepared by the present invention is beneficial to improving the long-term protection performance of epoxy-based powder coatings under high-temperature and high-pressure extreme working conditions.

[0005] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a preparation method of a modified silicone resin, comprising the following steps:

[0007] Mix methyltrimethoxysilane, phenyltriethoxysilane, isocyanatopropyltriethoxysilane with an alcohol-water solvent for hydrolysis and polycondensation to obtain a solution containing terminal isocyanate group polysiloxane; the hydrolysis and polycondensation is carried out under the condition that the pH value is 3 - 6;

[0008] Mix the solution containing terminal isocyanate group polysiloxane with dicyandiamide and amino-functionalized cage-like silsesquioxane for hybrid cross-linking polycondensation reaction to obtain a solution containing Si, O, C, and N hybrid cross-linked polymer;

[0009] Remove the solvent from the solution containing Si, O, C, and N hybrid cross-linked polymer to obtain the modified silicone resin.

[0010] Preferably, by mass parts, the methyltrimethoxysilane is 60 to 80 parts, the phenyltriethoxysilane is 20 to 40 parts, the isocyanatopropyltriethoxysilane is 15 to 25 parts, the dicyandiamide is 10 to 20 parts, and the aminated cage-like silsesquioxane is 5 to 10 parts.

[0011] Preferably, the temperature of the hydrolysis and polycondensation is 50 to 80 °C and the time is 2 to 4 h; the temperature of the hybridization and crosslinking polycondensation reaction is 60 to 100 °C and the time is 2 to 6 h.

[0012] The present invention provides a heavy-duty anti-corrosion powder coating, which comprises the following raw materials for preparation in mass percentage:

[0013] Epoxy resin 15 to 35%, linear phenolic epoxy resin 5 to 15%, modified silicone resin 15 to 25%, graphene-modified silicon-titanium nanopolymer slurry 2 to 5%, wear-resistant reinforcing filler 15 to 25%, mica powder 1 to 10%, pigment 0.5 to 2%, hydrophobic interface modifier 0.1 to 0.3%, fumed silica 0.1 to 1%, silica powder 5 to 15%, dispersant 0.5 to 1.5%, wetting agent 0.5 to 1.5%, defoaming agent 0.5 to 1.5%, conductive agent 0.4 to 1.5%, adhesion promoter 0.5 to 1.5%, leveling agent 0.5 to 1.5%, dicyandiamide curing agent 1 to 5%;

[0014] The wear-resistant reinforcing filler includes carbide and / or metal oxide; the hydrophobic interface modifier includes fluorocarbon silane coupling agent and / or modified polysiloxane copolymer; the modified silicone resin is the modified silicone resin prepared by the preparation method described in the above technical solution;

[0015] The graphene-modified silicon-titanium nanopolymer slurry comprises the following raw materials for preparation in mass parts: 40 to 60 parts of titanium hydride, 2 to 5 parts of active silica, 1 to 2 parts of silane coupling agent-modified graphene, 10 to 30 parts of silicon-modified epoxy resin, 3 to 6 parts of active diluent, 2 to 10 parts of N-methylpyrrolidone, 1 to 5 parts of dispersant, 1 to 5 parts of coupling agent, 0.01 to 0.1 part of catalyst, 0.1 to 0.2 part of wetting agent, and 0.1 to 0.2 part of wetting assistant.

[0016] Preferably, the epoxy equivalent of the epoxy resin is 600 to 1800.

[0017] Preferably, the carbide includes one or more of silicon carbide, titanium carbide and tungsten carbide; the metal oxide includes zirconia and / or ceramic alumina.

[0018] Preferably, the fluorocarbon silane coupling agent includes heptadecafluorodecyltriethoxysilane coupling agent, and the modified polysiloxane copolymer includes polyether siloxane.

[0019] Preferably, the particle size of the heavy-duty anti-corrosion powder coating is less than 70 microns, and the mass ratio of particles with a particle size less than 50 microns is ≥ 80%.

[0020] The present invention provides a method for preparing the heavy-duty anti-corrosion powder coating described in the above technical solution, comprising the following steps:

[0021] Premix the graphene-modified silicon-titanium nanopolymer slurry with a hydrophobic interface modifier to form a hydrophobized premixed slurry;

[0022] Mix the hydrophobized premixed slurry with a wear-resistant reinforcing filler to form a core-shell structured slurry;

[0023] Mix the core-shell structured slurry with epoxy resin, linear phenolic epoxy resin, modified silicone resin, pigment, mica powder, fumed silica, silica powder, dispersant, wetting agent, defoaming agent, conductive agent, adhesion promoter, leveling agent and dicyandiamide-based curing agent, and subject the obtained mixture to melt extrusion and then powder making to obtain the heavy-duty anti-corrosion powder coating.

[0024] The present invention provides the application of the heavy-duty anti-corrosion powder coating described in the above technical solution or the heavy-duty anti-corrosion powder coating prepared by the preparation method described in the above technical solution in the anti-corrosion of oilfield pipelines.

[0025] The present invention provides a method for preparing a modified silicone resin. First, hydrolytic condensation of methyltrimethoxysilane, phenyltriethoxysilane and isocyanatopropyltriethoxysilane forms a terminal isocyanate group polysiloxane. The methyltrimethoxysilane, phenyltriethoxysilane and isocyanatopropyltriethoxysilane take into account hardness, flexibility and heat resistance, and the isocyanate group in the formed terminal isocyanate group polysiloxane bridges dicyandiamide and amino-functionalized polyhedral oligomeric silsesquioxane (NH2-POSS) to form a hybrid network. The formation of this structure not only solves the problem of poor compatibility between dicyandiamide and the resin, but also enables the silicone to have a high crosslinking density (the crosslinking density can reach more than 95%) after curing, and the resin has excellent temperature and pressure resistance performance; the introduction of the NH2-POSS nano-reinforcing structure can further inhibit thermal oxidative degradation. The modified silicone resin prepared by the present invention is a special silicone resin that can be cured by dicyandiamide. After curing, the resin has a thermal decomposition temperature of more than 480 °C, and the coating is intact under the high-temperature test of 600 °C / 100 h (GB / T 1735-2009). As the main film-forming substances of the coating in combination with epoxy resin and linear phenolic epoxy resin, using a dicyandiamide-based curing agent can greatly improve the acid-boiling resistance and high-temperature resistance of the epoxy powder coating, and significantly improve the long-term protection performance of the epoxy powder coating under extreme working conditions of high temperature and high pressure.

[0026] The present invention provides a heavy-duty anti-corrosion powder coating, which comprises the following raw materials for preparation in mass percentage: 15-35% of epoxy resin, 5-15% of linear phenolic epoxy resin, 15-25% of modified silicone resin, 2-5% of graphene-silicon-titanium nano slurry, 15-25% of wear-resistant reinforcing filler, 1-10% of mica powder, 0.5-2% of pigment, 0.1-0.3% of hydrophobic interface modifier, 0.1-1% of fumed silica, 5-15% of silica powder, 0.5-1.5% of dispersant, 0.5-1.5% of wetting agent, 0.5-1.5% of defoaming agent, 0.4-1.5% of conductive agent, 0.5-1.5% of adhesion promoter, 0.5-1.5% of leveling agent, and 1-5% of dicyandiamide curing agent. In the present invention, the modified silicone resin is a silicone special resin that can be cured by dicyandiamide. It is compounded with epoxy resin and linear phenolic epoxy resin as the main film-forming substances of the coating, greatly improving the high-temperature resistance of the coating, while retaining the excellent adhesion and chemical resistance characteristics of epoxy resin and phenolic resin. The hydrophobic interface modifier can coat the solid particles in the graphene-modified silicon-titanium nano polymer slurry, and the resin and coupling agent in the graphene-modified silicon-titanium nano polymer slurry can also adsorb and anchor on the surface of the wear-resistant reinforcing filler to form a core-shell structure. This not only ensures the crosslinkable characteristics of the shell to participate in dicyandiamide curing together with the main resin in the powder coating formulation, but also optimizes the dispersion and stability of the hard-phase wear-resistant components. In this way, both the ultra-high density of the coating and excellent hardness and wear resistance are ensured. At the same time, the hydrophobic interface modifier can improve the overall hydrophobicity of the coating, enhancing the water resistance and the ability to resist the infiltration and penetration of various acid-base-salt ions in water. The graphene-modified silicon-titanium nano polymer slurry also contains crosslinkable epoxy groups, which can participate in the crosslinking with the curing agent together with other resins in the powder coating to improve the strength and density. The heavy-duty anti-corrosion powder coating provided by the present invention is a wear-resistant and anti-corrosion integrated coating with excellent interfacial bonding performance, capable of achieving long-term protection of the coating under extreme working conditions.

[0027] The results of the examples show that the wear resistance of the heavy-duty anti-corrosion powder coating provided by the present invention is ≥2.2 L / μm (abrasive erosion method), the adhesion: grade 5A (superior to the required grade 3A in the standard); the corrosion resistance: 10% HCl (room temperature, 90 days): no change in the coating, 3.5% NaCl (room temperature, 90 days): no change in the coating, crude oil (80°C, 90 days): no change in the coating; the high-temperature and high-pressure performance: condition 1: 180°C / 70 MPa / 16 h (NaOH solution, pH = 12.5), condition 2: 107°C / 35 MPa / 16 h (water / toluene / kerosene mixture), result: no bubbles in the coating, and the adhesion remains grade 5A. And the heavy-duty anti-corrosion powder coating undergoes a high-temperature and high-pressure simulation test of 220°C / 35 MPa H2S saturated aqueous solution (720 h), without foaming, and the adhesion is grade 1, showing excellent long-term protection performance under extreme working conditions.

[0028] The present invention provides a preparation method of the heavy-duty anti-corrosion powder coating described in the above technical solutions. The present invention adopts a multi-stage dispersion design. First, the hydrophobic interface modifier can coat the solid particles in the graphene-modified silicon-titanium nano-polymer slurry to form a hydrophobized premixed slurry. Moreover, the hydrophobic interface modifier has good compatibility with the coupling agent in the slurry and can crosslink with each other, making the hydrophobic interface modifier not easy to migrate. Then, the hydrophobized premixed slurry is mixed with the wear-resistant reinforcing filler. The resin and coupling agent in the graphene-modified silicon-titanium nano-polymer slurry adsorb and anchor on the surface of the wear-resistant reinforcing filler to form a core-shell structure, effectively improving the multi-phase compatibility and denseness of the coating. At the same time, the hydrophobic interface modifier and the graphene-silicon-titanium nano-slurry are more evenly distributed between the hard-phase particles of the coating.

[0029] The present invention provides an application of the heavy-duty anti-corrosion powder coating described in the above technical solutions or the heavy-duty anti-corrosion powder coating prepared by the preparation method described in the above technical solutions in the anti-corrosion of oilfield pipelines. The heavy-duty anti-corrosion powder coating provided by the present invention is particularly suitable for the long-term protection of oilfield pipelines under high temperature, high pressure and strong corrosion conditions. Description of the Drawings

[0030] Figure 1 It is the electron micrograph (a) of the ordinary epoxy powder coating after wear resistance test and the electron micrograph (b) of the heavy-duty anti-corrosion powder coating obtained in Comparative Example 1 after wear resistance test;

[0031] Figure 2 It is the electron micrograph (a) of the ordinary powder coating after wear resistance test and the electron micrograph (b) of the heavy-duty anti-corrosion powder coating obtained by multi-stage dispersion in Example 1 after wear resistance test;

[0032] Figure 3 It is the appearance of the heavy-duty anti-corrosion powder coating obtained by multi-stage dispersion in Example 1. Detailed Embodiments

[0033] The present invention provides a preparation method of a modified silicone resin, comprising the following steps:

[0034] Mix methyltrimethoxysilane, phenyltriethoxysilane, isocyanatopropyltriethoxysilane with an alcohol-water solvent for hydrolysis and polycondensation to obtain a solution containing terminal isocyanate group polysiloxane; the hydrolysis and polycondensation is carried out under the condition that the pH value is 3-6;

[0035] Mix the solution containing terminal isocyanate group polysiloxane with dicyandiamide and amino-functionalized cage-shaped silsesquioxane for a hybrid crosslinking polycondensation reaction to obtain a solution containing Si, O, C and N hybrid crosslinked polymer;

[0036] Remove the solvent from the solution containing Si, O, C and N hybrid crosslinked polymer to obtain the modified silicone resin.

[0037] In the present invention, unless otherwise specified, the raw materials involved are commercially available products well-known in the art.

[0038] In the present invention, methyltrimethoxysilane (MTMS), phenyltriethoxysilane (PTES), isocyanatepropyltriethoxysilane (IPTS) are mixed with an alcohol-water solvent for hydrolysis and polycondensation to obtain a solution containing isocyanate-terminated polysiloxane.

[0039] In the present invention, the methyltrimethoxysilane, phenyltriethoxysilane, and isocyanatepropyltriethoxysilane can balance the good hardness, flexibility, and heat resistance of the coating, and make the prepared resin have a suitable viscosity. In the present invention, the alcohol in the alcohol-water solvent is preferably ethanol, and the volume ratio of the alcohol to water is preferably 95:5. In the present invention, the hydrolysis and polycondensation are carried out under the condition that the pH value is 3 to 6, and the pH value can be 3, 4, 4.5, 5, or 6; in the present invention, it is preferred to add methyltrimethoxysilane, phenyltriethoxysilane, and isocyanatepropyltriethoxysilane to an alcohol-water solvent with a pH value of 3 to 6 for hydrolysis and polycondensation. In the present invention, the temperature of the hydrolysis and polycondensation is preferably 50 to 80 °C, which can be 50, 60, 70, or 80 °C, and the time is preferably 2 to 4 h, which can be 2, 3, or 4 h. The hydrolysis and polycondensation are preferably carried out under stirring conditions. The reactions involved in the process of the hydrolysis and polycondensation are as follows (note: the isocyanate group (-NCO) is stable under acidic conditions and does not participate in hydrolysis):

[0040] Hydrolysis of MTMS: CH3Si(OCH3)3 + 3H2O → CH3Si(OH)3 + 3CH3OH;

[0041] Hydrolysis of PTES: C6H5Si(OCH2CH3)3 + 3H2O → C6H5Si(OH)3 + 3CH3CH2OH;

[0042] Hydrolysis of IPTS: (NCO)C3H6Si(OCH2CH3)3 + 3H2O → (NCO)C3H6Si(OH)3 + 3CH3CH2OH;

[0043] Polycondensation stage: The silanols form Si-O-Si bonds through dehydration condensation, and at the same time, isocyanate silanol (the hydrolysis product of IPTS) acts as a capping agent, occupying the end of the polymer chain.

[0044] After obtaining a solution containing terminal isocyanate polysiloxane, the present invention mixes the solution containing terminal isocyanate polysiloxane with dicyandiamide and amino-type cage-type silsesquioxane (or amino-type cage-type polysilsesquioxane, NH2-POSS) to carry out a hybrid cross-linking polycondensation reaction to obtain a solution containing a Si, O, C and N hybrid (denoted as Si-OCN hybrid) polymer.

[0045] In an embodiment of the present invention, the NH2-POSS is purchased from Xi'an Qiyue Biotechnology Co., Ltd. In the present invention, the temperature of the hybrid cross-linking polycondensation reaction is preferably 60 to 100° C., and can be 70, 80 or 90° C., and the time is preferably 2 to 6 hours, and can be 3, 4 or 5 hours. The present invention preferably adds dicyandiamide and NH2-POSS to the solution containing the terminal isocyanate polysiloxane, and heats the temperature to 60 to 100° C. to carry out the hybrid cross-linking polycondensation reaction. During the hybrid cross-linking polycondensation reaction, the reactions involved are as follows:

[0046] Pre-reaction of dicyandiamide (DCD) with isocyanate silane:

[0047] The amino group (-NH2) of dicyandiamide ((NH2)2C=NC≡N) first reacts with the isocyanate group (-NCO) of the isocyanate-terminated polysiloxane to form a urea bond (-NH-CO-NH-) bridging structure (R-NH-C(=O)-NH)2C=NC≡N:

[0048] (NH2)2C=NC≡N+2R-NCO→(R-NH-C(=O)-NH)2C=NC≡N (R is the organosilicon part of the silane, such as -C3H6Si(OH)3). This step is the initial chemical bonding between the siloxane skeleton and dicyandiamide to form an organic-inorganic hybrid precursor. The two amino groups of dicyandiamide preferentially react with the -NCO of the terminal isocyanate polysiloxane, while the terminal cyano group is retained for subsequent condensation with NH2-POSS.

[0049] The amino group of NH2-POSS reacts with the cyano group of dicyandiamide:

[0050] The amino group (-NH2) of NH2-POSS undergoes a nucleophilic addition reaction with the cyano group (-C≡N) in the pre-reaction product to generate POSS with an imine bond (-NH-C=N-). This reaction anchors the POSS nanostructure into the silicone resin network through the condensation of the cyano group and the amino group; ultimately, a hybrid network containing Si, O, C and N is formed.

[0051] In the present invention, the viscosity of the solution containing the Si, O, C and N hybrid polymer is preferably 2000 to 6000 mPa·s, and may be 2500, 3000, 4000 or 5000 mPa·s.

[0052] After obtaining the solution containing the Si, O, C and N hybrid polymer, the present invention removes the solvent from the solution containing the Si, O, C and N hybrid polymer to obtain the modified silicone resin.

[0053] In the present invention, by mass parts, the methyltrimethoxysilane is preferably 60 to 80 parts, and can be 60, 70 or 80 parts; the phenyltriethoxysilane is preferably 20 to 40 parts, and can be 20, 30 or 40 parts; the isocyanate group propyltriethoxysilane is preferably 15 to 25 parts, and can be 15, 20 or 25 parts; the dicyandiamide is preferably 10 to 20 parts, and can be 10, 15 or 20 parts; the aminated cage-like silsesquioxane is preferably 5 to 10 parts, and can be 5, 6, 7, 8, 9 or 10 parts.

[0054] In the present invention, the method for removing the solvent can be vacuum distillation, and the temperature of the vacuum distillation can be 120 °C. After removing the solvent, the present invention also preferably pulverizes the obtained material to obtain the powdered modified silicone resin.

[0055] The modified silicone resin prepared by the present invention is a silicone special resin that can be cured by dicyandiamide. When compounded with epoxy resin and linear phenolic epoxy resin as the main film-forming substances of the coating and using a dicyandiamide-based curing agent, it can greatly improve the acid-boiling resistance and high-temperature resistance of the epoxy powder coating, and significantly improve the long-term protection performance of the epoxy powder coating under extreme working conditions of high temperature and high pressure.

[0056] The present invention provides a heavy-duty anticorrosive powder coating, which comprises the following preparation raw materials in mass percentage:

[0057] Epoxy resin 15 - 35%, linear phenolic epoxy resin 5 - 15%, modified silicone resin 15 - 25%, graphene silicon titanium nano-slurry 2 - 5%, wear-resistant reinforcing filler 15 - 25%, mica powder 1 - 10%, pigment 0.5 - 2%, hydrophobic interface modifier 0.1 - 0.3%, fumed silica 0.1 - 1%, silica powder 5 - 15%, dispersant 0.5 - 1.5%, wetting agent 0.5 - 1.5%, defoaming agent 0.5 - 1.5%, conductive agent 0.4 - 1.5%, adhesion promoter 0.5 - 1.5%, leveling agent 0.5 - 1.5%, dicyandiamide-based curing agent 1 - 5%;

[0058] The wear-resistant reinforcing filler includes carbides and / or metal oxides; the hydrophobic interface modifier includes fluorosilane coupling agent and / or modified polysiloxane copolymer; the modified silicone resin is the modified silicone resin prepared by the preparation method described in the above technical solution.

[0059] By mass percentage, the raw materials for preparing the heavy-duty anti-corrosion powder coating provided by the present invention include 15-35% of epoxy resin, which can be 20%, 30%, 33% or 34%. In the present invention, the epoxy equivalent of the epoxy resin is preferably 600-1800, which can be 600-650, 700-750, 780-850 or 1500-1800. Selecting the above epoxy resin is beneficial to balance the melt viscosity, reaction activity, film toughness, etc.

[0060] By mass percentage, the raw materials for preparing the heavy-duty anti-corrosion powder coating provided by the present invention include 5-15% of linear phenolic epoxy resin, which can be 7%, 8% or 10%. In the present invention, the linear phenolic epoxy resin is preferably purchased from Hunan Selway New Material Technology Co., Ltd., with the brand number R-0273. In the present invention, the linear phenolic epoxy resin can improve the flexibility, chemical resistance and autoclave resistance of the coating.

[0061] By mass percentage, the raw materials for preparing the heavy-duty anti-corrosion powder coating provided by the present invention include 15-25% of modified silicone resin, which can be 15%, 20% or 25%. The modified silicone resin is the modified silicone resin prepared by the preparation method described in the above technical solution. In the present invention, the modified silicone resin is a silicone special resin that can be cured by dicyandiamide. It is compounded with epoxy resin and linear phenolic epoxy resin as the main film-forming substance of the coating, greatly improving the high-temperature resistance of the coating, and at the same time retaining the excellent adhesion and chemical resistance of epoxy resin and phenolic resin.

[0062] By mass percentage, the raw materials for preparing the heavy-duty anti-corrosion powder coating provided by the present invention include 2-5% of graphene-modified silicon-titanium nanopolymer slurry, which can be 2%, 3%, 4% or 5%. In the present invention, the graphene-modified silicon-titanium nanopolymer slurry includes the following raw materials in parts by mass: 40-60 parts of titanium hydride, 2-5 parts of active silica, 1-2 parts of silane coupling agent-modified graphene, 10-30 parts of silicon-modified epoxy resin, 3-6 parts of active diluent, 2-10 parts of N-methylpyrrolidone, 1-5 parts of dispersant, 1-5 parts of coupling agent, 0.01-0.1 part of catalyst, 0.1-0.2 part of wetting agent, 0.1-0.2 part of wetting assistant. The graphene-modified silicon-titanium nanopolymer slurry specifically refers to Chinese Patent CN113416469A (application number 202110788222.4). In the present invention, the modified graphene silicon-titanium nanopolymer slurry can crosslink and react with dicyandiamide, and at the same time, the formed nanostructured polymer network structure is distributed inside the coating, mainly used to improve the overall compactness and anti-permeability of the coating.

[0063] By mass percentage, the raw materials for preparing the heavy-duty anti-corrosion powder coating provided by the present invention include 15-25% of wear-resistant reinforcing fillers, which can be 15%, 17%, 18%, 20% or 25%. In the present invention, the wear-resistant reinforcing fillers include carbides and / or metal oxides. The carbides preferably include one or more of silicon carbide, titanium carbide and tungsten carbide, and the metal oxides preferably include zirconia and / or ceramic alumina. When the wear-resistant reinforcing fillers include carbides and metal oxides, the mass ratio of the carbides to the metal oxides is preferably 1:2-2.4. In the present invention, the particle size of the carbides is preferably 1250-3000 mesh, and the particle size of the metal oxides is preferably 1250-2000 mesh. In the present invention, the silicon carbide mainly plays a role in wear resistance, and the metal oxides play a role in wear resistance and corrosion resistance to acids, alkalis and salts.

[0064] By mass percentage, the raw materials for preparing the heavy-duty anti-corrosion powder coating provided by the present invention include 1-10% of mica powder, which can be 1%, 5% or 10%. In the present invention, the mica powder is preferably mica powder GA-4 (purchased from Anhui Gerui New Material Technology Co., Ltd.); the mica powder has a flaky structure and can improve the anti-cracking and anti-permeation effects while improving the wear resistance of the coating.

[0065] By mass percentage, the raw materials for preparing the heavy-duty anti-corrosion powder coating provided by the present invention include 0.5-2% of pigments, which can be 0.5%, 1% or 2%. In the present invention, the pigment is preferably carbon black, and the carbon black can be Cabot 660R; the pigment is used for color adjustment.

[0066] By mass percentage, the raw materials for preparing the heavy-duty anti-corrosion powder coating provided by the present invention include 0.1-0.3% of a hydrophobic interface modifier, which can be 0.1%, 0.2% or 0.3%. In the present invention, the hydrophobic interface modifier includes a fluorocarbon silane coupling agent and / or a modified polysiloxane copolymer. The fluorocarbon silane coupling agent preferably includes a heptadecafluorodecyltriethoxysilane coupling agent, and the modified polysiloxane copolymer preferably includes a polyether siloxane, and the polyether siloxane can be Tegopren 450. In the present invention, the hydrophobic interface modifier can improve the hydrophobicity of the coating and reduce the penetration of water and ions in water.

[0067] By mass percentage, the raw materials for preparing the heavy-duty anti-corrosion powder coating provided by the present invention include 0.1-1% of fumed silica, which can be 0.1%, 0.2%, 0.5% or 1%. In the present invention, the fumed silica is preferably fumed silica R974 (Degussa); the fumed silica makes the powder coating have better fluidity, is easy to spray, and at the same time helps to improve the hydrophobicity of the coating and has an anti-sagging effect.

[0068] By mass percentage, the raw materials for preparing the heavy-duty anti-corrosion powder coating provided by the present invention include 5-15% of silica powder, which can be 5%, 8%, 10% or 15%. In the present invention, the particle size of the silica powder is preferably 1250-2000 mesh; the silica powder is used as a wear-resistant filler, which can reduce costs.

[0069] By mass percentage, the raw materials for preparing the heavy-duty anti-corrosion powder coating provided by the present invention include 0.5-1.5% of a dispersant, which can be 0.5%, 1% or 1.5%. In the present invention, the dispersant is preferably SA516 dispersant (Liuan Jietongda New Materials Co., Ltd.); the dispersant can make the powder materials more easily and stably dispersed.

[0070] By mass percentage, the raw materials for preparing the heavy-duty anti-corrosion powder coating provided by the present invention include 0.5-1.5% of a wetting agent, which can be 0.5%, 1%, 1.2% or 1.5%. In the present invention, the wetting agent is preferably 701 wetting agent (Huangshan Jinfeng Industry Co., Ltd.); the wetting agent helps to wet the powder materials during the coating production process, so that the dispersant can be better distributed on the surface of the powder.

[0071] By mass percentage, the raw materials for preparing the heavy-duty anti-corrosion powder coating provided by the present invention include 0.5-1.5% of an anti-foaming agent, which can be 0.5%, 1% or 1.5%. In the examples of the present invention, the anti-foaming agent is preferably 542DG anti-foaming agent (Troy); the anti-foaming agent is used for the release of gas during the curing of the coating and is not likely to generate bubbles in the coating.

[0072] By mass percentage, the raw materials for preparing the heavy-duty anti-corrosion powder coating provided by the present invention include 0.4-1.5% of a conductive agent, which can be 0.4%, 0.5%, 1% or 1.5%. In the present invention, the conductive agent is preferably conductive mica powder with a particle size of 5-20 microns; the conductive agent is used to improve the conductivity of the coating during electrostatic spraying, so that the coating can be better sprayed on the workpiece.

[0073] By mass percentage, the raw materials for preparing the heavy-duty anti-corrosion powder coating provided by the present invention include 0.5-1.5% of an adhesion promoter, which can be 0.5%, 1% or 1.5%. In the present invention, the adhesion promoter is preferably BYK-3942P (BYK).

[0074] By mass percentage, the raw materials for preparing the heavy-duty anti-corrosion powder coating provided by the present invention include 0.5-1.5% of a leveling agent, which can be 0.5%, 1%, 1.2% or 1.5%. In the present invention, the leveling agent is preferably PL-200 leveling agent (Eastron); the leveling agent can reduce the surface tension during the baking and curing melting of the coating, improve the leveling property of the coating, and is not likely to generate uneven orange peel.

[0075] In terms of mass percentage, the raw materials for preparing the heavy-duty anti-corrosion powder coating provided by the present invention include 1-5% of dicyandiamide curing agent, which can be 2%, 3%, 4% or 5%. In the present invention, the dicyandiamide curing agent is preferably K7104 (modified dicyandiamide from Lu'an Jietongda New Materials Co., Ltd.). In the present invention, the dicyandiamide curing agent crosslinks with the resin to finally cure the coating into a coating.

[0076] In the present invention, the particle size of the heavy-duty anti-corrosion powder coating is preferably less than 70 microns, and the mass ratio of particles with a particle size less than 50 microns is ≥80%.

[0077] The heavy-duty anti-corrosion powder coating provided by the present invention is an integrated wear-resistant and anti-corrosion coating with excellent interfacial bonding performance, which can achieve long-term protection of the coating under extreme working conditions (70 MPa / 180 °C high-pressure and high-temperature test, ≥16 h). While traditional epoxy powder coatings are prone to "bubbling-peeling" failure under 70 MPa high pressure and 148 °C high temperature, insufficient wear resistance leads to serious wear of the inner wall of the pipeline (abrasion resistance by sand-falling method ≤2.0 L / μm), and the interfacial bonding strength between the coating and the substrate is low (adhesion ≤5A level).

[0078] The present invention provides a preparation method of the heavy-duty anti-corrosion powder coating described in the above technical solutions, including the following steps:

[0079] Premix the graphene-modified silicon-titanium nano-polymer slurry with the hydrophobic interface modifier to form a hydrophobized premix slurry;

[0080] Mix the hydrophobized premix slurry with pigments and wear-resistant reinforcing fillers to form a core-shell structured slurry;

[0081] Mix the core-shell structured slurry with epoxy resin, linear phenolic epoxy resin, modified silicone resin, mica powder, fumed silica, silica powder, dispersant, wetting agent, defoamer, conductive agent, adhesion promoter, leveling agent and dicyandiamide curing agent, and perform melt extrusion and powder making on the obtained mixture to obtain the heavy-duty anti-corrosion powder coating.

[0082] The present invention premixes a graphene-modified silicon-titanium nano-polymer slurry with a hydrophobic interface modifier to form a hydrophobized premixed slurry. In the present invention, a coupling agent (such as an epoxy group silane coupling agent) in the graphene-modified silicon-titanium nano-polymer slurry can undergo silanol condensation with the hydrophobic interface modifier (a fluorocarbon silane coupling agent and / or a modified polysiloxane copolymer). The graphene-modified silicon-titanium nano-polymer slurry contains solid particulate matter (silica and titanium hydride). The hydrophobic interface modifier migrates to the surface of the solid particles and couples and coats them, and also undergoes condensation with the silane coupling agent on the surface of the solid particles, so that the hydrophobic interface modifier does not migrate but is anchored around the solid particles of the slurry. Therefore, a hydrophobized coating layer can be formed through the said premixing. In the present invention, the water contact angle of the surface of the coating cured by the hydrophobized premixed slurry and an amine curing agent for epoxy resin is ≥110°.

[0083] After obtaining the hydrophobized premixed slurry, the present invention mixes the hydrophobized premixed slurry with a wear-resistant reinforcing filler to form a core-shell structured slurry. In the present invention, the mixing is preferably carried out in a high-speed disperser, and the rotation speed is preferably 5000 - 8000 rpm, which can be 5000, 6000, 7000 or 8000 rpm, and the mixing time is preferably 15 - 20 min, which can be 15, 17 or 20 min. Because the graphene-modified silicon-titanium nano-polymer slurry contains resin (silicon-modified epoxy resin) and a large amount of coupling agents, which adsorb and anchor on the surface of the solid wear-resistant reinforcing filler, a core-shell structure can be formed through the said mixing.

[0084] After obtaining the core-shell structured slurry, the present invention mixes the core-shell structured slurry with epoxy resin, linear phenolic epoxy resin, modified silicone resin, pigment, mica powder, fumed silica, silica powder, dispersant, wetting agent, defoaming agent, conductive agent, adhesion promoter, leveling agent and dicyandiamide curing agent, and powders the obtained mixture after melt extrusion to obtain the heavy-duty anticorrosive powder coating.

[0085] In the present invention, the mixing is preferably high-speed dispersing mixing, and the rotation speed of the high-speed dispersing mixing is preferably 1000 - 2000 rpm, which can be 1000, 1500 or 2000 rpm, and the time is preferably 20 - 60 min, which can be 20, 30, 40, 50 or 60 min.

[0086] In the present invention, the melt extrusion is preferably twin-screw extrusion, specifically carried out in a twin-screw extruder. Starting from the feeding end, the twin-screw extruder is sequentially provided with Zone I, Zone II and Zone III. The temperature of Zone I is preferably 95 - 110 °C, which can be 95, 100, 105 or 110 °C, the temperature of Zone II is preferably 110 - 130 °C, which can be 110, 120 or 130 °C, and the temperature of Zone III is preferably 90 - 100 °C, which can be 90, 95 or 100 °C.

[0087] In the present invention, the method for powder making is preferably as follows: slicing and pulverizing the material after melt extrusion, and then sieving; the sieving is preferably through a 200-mesh sieve.

[0088] The present invention provides the application of the heavy-duty anti-corrosion powder coating described in the above technical solution or the heavy-duty anti-corrosion powder coating prepared by the preparation method described in the above technical solution in the anti-corrosion of oilfield pipelines.

[0089] The heavy-duty anti-corrosion powder coating provided by the present invention is particularly suitable for the long-term protection of oilfield pipelines under high temperature, high pressure and strong corrosion conditions, and has passed the authoritative testing and certification of the National Petroleum Tubular Goods Quality Inspection and Testing Center (CNPC).

[0090] In the present invention, the method of the application is preferably as follows:

[0091] After the oilfield pipeline is pretreated, it is preheated;

[0092] The heavy-duty anti-corrosion powder coating is sprayed on the preheated oilfield pipeline, and then cured.

[0093] In the present invention, the pretreatment is specifically sandblasting and derusting the oilfield pipeline to Sa2.5 - 3 levels (steel sand particle size 0.8 - 1.2 mm), and the surface roughness Ra of the pretreated oilfield pipeline is preferably 35 - 75 μm. In the present invention, the temperature of the preheating is preferably 180 - 220 °C. In the present invention, the parameters of the spraying are preferably: spraying thickness: 0.35 ± 0.05 mm; rotation speed: 200 - 250 rpm; spray gun moving speed: 20 - 30 m / min; the parameters of the curing are preferably: temperature: 200 - 240 °C; time: ≥ 30 min; rotational curing (to prevent sagging).

[0094] In order to further illustrate the present invention, the following examples are used to describe in detail the preparation method of the modified silicone resin, the heavy-duty anti-corrosion powder coating and its preparation method and application provided by the present invention, but they should not be construed as limiting the protection scope of the present invention.

[0095] Example 1

[0096] The heavy-duty anti-corrosion powder coating, and the preparation raw materials and their mass fractions are shown in Table 1.

[0097] Table 1 Preparation raw materials of the heavy-duty anti-corrosion powder coating and the mass fractions of each raw material

[0098]

[0099]

[0100] The preparation steps of the modified silicone resin in Table 1 are as follows:

[0101] (1) Hydrolysis reaction: 70 g of methyltrimethoxysilane (MTMS), 30 g of phenyltriethoxysilane (PTES), and 20 g of isocyanatepropyltriethoxysilane were added to a reactor containing 100 mL of ethanol-water (volume ratio of ethanol to water: 95:5) with a pH of 4.5, and stirred at 60°C for 2 h.

[0102] (2) Polycondensation modification: 15 g of dicyandiamide and 8 g of NH2-POSS (purchased from Xi'an Qiyue Biological) were added to the product of step (1), and the temperature was raised to 80°C for reaction for 3 h until the viscosity of the system reached 2500 mPa·s;

[0103] (3) Solid powdering treatment: After vacuum desolventization at 120°C, the modified silicone resin powder is crushed.

[0104] The preparation steps of heavy-duty anti-corrosion powder coating are as follows:

[0105] (1) Primary dispersion: Graphene-modified silicon titanium nanopolymer slurry is premixed with a hydrophobic interface modifier to form a hydrophobic premixed slurry (contact angle ≥ 110°);

[0106] (2) Secondary dispersion: The premixed slurry obtained in step (1) and fillers (ceramic alumina and silicon carbide) were treated in a high-speed disperser (6000 rpm) for 20 min to form a core-shell structure slurry;

[0107] (3) Tertiary dispersion: After adding the remaining components to the material obtained in step (2), high-speed mixing and dispersion (rotating speed 2000 rpm, processing time 40 min) are adopted; then, the mixture is melt-extruded and sliced by a twin-screw extruder with segmented temperature control (zone I 105°C / zone II 120°C / zone III 100°C), and sieved through 200 mesh. The particle size of the powder coating is less than 70 μm, and the mass proportion of particles with a particle size of less than 50 μm is ≥80%.

[0108] Comparative Example 1

[0109] The Tego 450 in Table 1 is omitted, and the rest is the same as Table 1. The preparation steps of the heavy-duty anti-corrosion powder coating are as follows (i.e., the hydrophobic functional surface modification is not performed in Comparative Example 1):

[0110] The graphene-modified silicon-titanium nanopolymer slurry, fillers (ceramic alumina and silicon carbide) and other remaining components are dispersed by high-speed mixing (rotating speed 2000 rpm, processing time 40 min); then melt-extruded and sliced by a twin-screw extruder with segmented temperature control (zone I 105°C / zone II 120°C / zone III 100°C), and sieved through 200 mesh. The powder coating particle size is less than 70 microns, and the mass proportion of particles with a particle size of less than 50 microns is ≥80%.

[0111] The performance of the heavy-duty anti-corrosion powder coating prepared in Example 1 was tested (detected by CNPC, and the detection was based on the standard SY / T 6717-2016). The test results are as follows:

[0112] Appearance: flat, uniform, smooth, without defects such as bubbles, orange peel and running;

[0113] Dry film thickness: 277.5 μm;

[0114] Leakage points: no leakage points were seen;

[0115] Abrasion resistance: 2.2 L / μm (falling sand method);

[0116] Adhesion: Grade 5A (superior to the required Grade 3A in the standard);

[0117] Resistance to chemical medium corrosion:

[0118] 10% HCl (room temperature, 90 days): no change in the coating,

[0119] 3.5% NaCl (room temperature, 90 days): no change in the coating,

[0120] Crude oil (80 °C, 90 days): no change in the coating;

[0121] High temperature and high pressure performance:

[0122] Condition 1: Liquid phase: NaOH solution (pH = 12.5) and H2SO4 solution (pH = 2) were respectively carried out at 180 °C / 70 MPa / 16 h, the specimen was completely immersed in the liquid, and pressurized with gas N2; Condition 2: Liquid phase: a mixed liquid of water, toluene and kerosene in equal volume ratio, 107 °C / 35 MPa / 16 h, 2 / 3 of the specimen was immersed in the liquid, and pressurized with CO2; The three test results under the above two conditions: no bubbles in the coating, and the adhesion remained at Grade 5A.

[0123] Technical effect: The abrasion resistance was improved by ≥ 26.7% (compared with the required 2.0 L / μm in the standard); The adhesion was improved by ≥ 66.7% (compared with the required Grade 3A in the standard); Passed the 16-hour extreme working condition test (180 °C / 70 MPa).

[0124] Figure 1 are the SEM images (a) of the coating of commercially available ordinary fusion-bonded epoxy powder coating after abrasion resistance test and the SEM image (b) of the heavy-duty anti-corrosion powder coating obtained in Comparative Example 1 after abrasion resistance test. Figure 2 are the SEM images (a) of the coating of commercially available ordinary fusion-bonded epoxy powder coating after abrasion resistance test and the SEM image (b) of the heavy-duty anti-corrosion powder coating obtained in Example 1 after multi-stage dispersion and abrasion resistance test. Figure 2 The ordinary fusion-bonded epoxy powder coating in Figure 1The ordinary fusion-bonded epoxy powder coatings therein were purchased from different manufacturers. Figure 1 As can be seen from Figure 1 in (a) than Figure 1 in (b), the pigment particle size inside the coating is much larger, and Figure 1 in (a) is far less Figure 1 dense than (b) in, and the abrasion marks are also more obvious. Figure 2 In, the pores inside the coating of (a) are significantly larger and more than those of (b), and the abrasion marks are obvious. Figure 2 Even when the magnification of observation of (b) is Figure 1 and Figure 2 twice that of (a) in, almost no agglomerated solid particles can be seen inside the coating, and the abrasion marks are the smallest.

[0125] Figure 3 The appearance of the heavy-duty anti-corrosion powder coating obtained by multi-stage dispersion of Example 1 can be seen that the surface of the coating is smooth, uniform and delicate.

[0126] The heavy-duty anti-corrosion powder coating prepared in Example 1 was subjected to a high-temperature and high-pressure simulation test (refer to SY / T6717-2016), and compared with the traditional fusion-bonded epoxy coating. The test conditions and results are shown in Table 2.

[0127] Table 2 High-temperature and high-pressure simulation test results

[0128]

[0129] Example 2

[0130] A heavy-duty anti-corrosion powder coating, the preparation raw materials and mass fractions thereof are shown in Table 3, and the rest are the same as those in Example 1.

[0131] Table 3 Preparation raw materials of the heavy-duty anti-corrosion powder coating and the mass fractions of each raw material

[0132]

[0133] Example 3

[0134] A heavy-duty anti-corrosion powder coating, the preparation raw materials and mass fractions thereof are shown in Table 4, and the rest are the same as those in Example 1.

[0135] Table 4 Preparation raw materials of the heavy-duty anti-corrosion powder coating and the mass fractions of each raw material

[0136]

[0137] The performance test results of the heavy-duty anti-corrosion powder coatings prepared in Examples 2 to 3 are shown in Table 5.

[0138] Table 5 Performance test results of the heavy-duty anti-corrosion powder coatings prepared in Examples 2 to 3

[0139]

[0140] As can be seen from the above embodiments, the heavy-duty anti-corrosion powder coating provided by the present invention is an integrated wear-resistant and anti-corrosion coating with excellent interfacial bonding performance, and can achieve long-term protection of the coating under extreme working conditions.

[0141] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on 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 preparation method of a modified silicone resin, characterized in that, It includes the following steps: Mix methyltrimethoxysilane, phenyltriethoxysilane, isocyanatopropyltriethoxysilane with an alcohol-water solvent for hydrolysis and polycondensation to obtain a solution containing isocyanate-terminated polysiloxane; the hydrolysis and polycondensation is carried out under the condition of a pH value of 3 to 6; Mix the solution containing isocyanate-terminated polysiloxane with dicyandiamide and aminated cage-like silsesquioxane for a hybrid crosslinking polycondensation reaction to obtain a solution containing a Si, O, C and N hybrid crosslinked polymer; Remove the solvent from the solution containing the Si, O, C and N hybrid crosslinked polymer to obtain the modified silicone resin.

2. The preparation method according to claim 1, characterized in that, By mass, the methyltrimethoxysilane is 60 to 80 parts, the phenyltriethoxysilane is 20 to 40 parts, the isocyanatopropyltriethoxysilane is 15 to 25 parts, the dicyandiamide is 10 to 20 parts, and the aminated cage-like silsesquioxane is 5 to 10 parts.

3. The preparation method according to claim 1 or 2, characterized in that, The temperature of the hydrolysis and polycondensation is 50 to 80 °C and the time is 2 to 4 h; the temperature of the hybrid crosslinking polycondensation reaction is 60 to 100 °C and the time is 2 to 6 h.

4. A heavy-duty anti-corrosion powder coating, characterized in that, It includes the following preparation raw materials by mass percentage: Epoxy resin 15 - 35%, linear phenolic epoxy resin 5 - 15%, modified silicone resin 15 - 25%, graphene-modified silicon-titanium nanopolymer slurry 2 - 5%, wear-resistant reinforcing filler 15 - 25%, mica powder 1 - 10%, pigment 0.5 - 2%, hydrophobic interface modifier 0.1 - 0.3%, fumed silica 0.1 - 1%, silica powder 5 - 15%, dispersant 0.5 - 1.5%, wetting agent 0.5 - 1.5%, defoaming agent 0.5 - 1.5%, conductive agent 0.4 - 1.5%, adhesion promoter 0.5 - 1.5%, leveling agent 0.5 - 1.5%, dicyandiamide-based curing agent 1 - 5%; The wear-resistant reinforcing filler includes carbide and / or metal oxide; the hydrophobic interface modifier includes fluorocarbon silane coupling agent and / or modified polysiloxane copolymer; the modified silicone resin is the modified silicone resin prepared by the preparation method described in any one of claims 1 to 3; The graphene-modified silicon-titanium nanopolymer slurry includes the following preparation raw materials by mass: 40 - 60 parts of titanium hydride, 2 - 5 parts of active silica, 1 - 2 parts of silane coupling agent-modified graphene, 10 - 30 parts of silicon-modified epoxy resin, 3 - 6 parts of active diluent, 2 - 10 parts of N-methylpyrrolidone, 1 - 5 parts of dispersant, 1 - 5 parts of coupling agent, 0.01 - 0.1 parts of catalyst, 0.1 - 0.2 parts of wetting agent, 0.1 - 0.2 parts of wetting assistant.

5. The heavy-duty anti-corrosion powder coating according to claim 4, wherein The epoxy equivalent of the epoxy resin is 600 - 1800.

6. The heavy-duty anti-corrosion powder coating according to claim 4, wherein, The carbide includes one or more of silicon carbide, titanium carbide and tungsten carbide; the metal oxide includes zirconia and / or ceramic alumina.

7. The heavy-duty anti-corrosion powder coating according to claim 4, wherein The fluorocarbon silane coupling agent includes heptadecafluorodecyltriethoxysilane, and the modified polysiloxane copolymer includes polyether siloxane.

8. The heavy-duty anticorrosive powder coating according to any one of claims 4 to 7, characterized in that The particle size of the heavy-duty anti-corrosion powder coating is less than 70 microns, and the mass proportion of particles with a particle size less than 50 microns is ≥80%.

9. The preparation method of the heavy-duty anti-corrosion powder coating according to any one of claims 4 to 8, characterized in that, It includes the following steps: Premix graphene-modified silicon-titanium nanopolymer slurry with a hydrophobic interface modifier to form a hydrophobized premixed slurry; Mix the hydrophobized premixed slurry with wear-resistant reinforcing fillers to form a core-shell structured slurry; Mix the core-shell structured slurry with epoxy resin, linear phenolic epoxy resin, modified silicone resin, pigments, mica powder, fumed silica, silica powder, dispersant, wetting agent, defoamer, conductive agent, adhesion promoter, leveling agent, and dicyandiamide-based curing agent, and subject the obtained mixture to melt extrusion and then powder making to obtain the heavy-duty anti-corrosion powder coating.

10. Application of the heavy-duty anti-corrosion powder coating according to any one of claims 4 to 8 or the heavy-duty anti-corrosion powder coating prepared by the preparation method according to claim 9 in anti-corrosion of oilfield pipelines.

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