Anti-corrosion and thermal insulation coating for oil pipe and preparation process therefor

Abstract

The present invention provides an anti-corrosion and thermal insulation coating for an oil pipe and a preparation process therefor. The preparation process comprises: (1) forming a coupling agent layer on the outer wall surface of an oil pipe; (2) forming a polyaniline layer on the surface of the coupling agent layer; and (3) forming an outer coating having anti-corrosion and thermal insulation properties on the surface of the polyaniline layer. The present invention further provides an anti-corrosion and thermal insulation coating for an oil pipe. According to the anti-corrosion and thermal insulation coating for an oil pipe and the preparation process therefor provided in the present invention, an anti-corrosion and connection transition layer is formed, and a main coating is connected to a metal matrix by means of the transition layer, thereby maintaining good stability under a variable temperature condition, and prolonging the service life of the coating.

Description

Anti-corrosion and thermal insulation coating for oil pipe and preparation process thereof

[0001] Cross-reference information

[0002] This application claims priority to the Chinese patent application filed with the Patent Office of China on January 9, 2024, with application number 202410034778.8 and invention name “Anti-corrosion and thermal insulation coating for oil pipes and its preparation process”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The invention belongs to the field of composite material preparation, and particularly relates to an anti-corrosion and thermal insulation coating for oil pipes and a preparation process thereof. Background Art

[0004] During the development of oil reservoirs, crude oil flows from the oil layer into the bottom of the well and is then lifted from the bottom of the well along the wellbore to the wellhead. During the oil and gas lifting process, heat diffuses from the production oil pipe to the external annular area, causing the fluid temperature in the pipe to drop, forming gas hydrates and wax deposits. Part of the wax crystals in the oil flow is produced with the oil flow, and part of it gathers, condenses and adheres to the metal surface of the oil well facilities, causing the oil pump and tubing rod to be blocked by wax.

[0005] As mentioned above, wax deposition in oil wellbores is primarily caused by a drop in temperature due to heat dissipation from the pipe wall. To minimize this temperature loss, a corrosion-resistant, thermally insulating coating is applied to the outer wall of the pipe. This prevents wax deposition during crude oil production and ensures normal production.

[0006] CN202111575170.9 relates to the use of Parmax resin in the insulation layer of oil pipes. Test results show that the thermal insulation of the oil pipes is significantly improved, wax is not easily deposited inside the production pipes, and the fluidity is good. However, the patent does not provide a bonding method between the Parmax resin and the oil pipes. Due to the chemical and physical properties of Parmax resin, it is difficult for Parmax resin to form a strong bond with metal surfaces such as oil pipes without special treatment. During long-term use, frequent thermal expansion and contraction and creep deformation of the oil pipes can easily cause the Parmax resin and the oil pipes to separate, resulting in a shorter service life.

[0007] CN201210172354.5 relates to a highly corrosion-resistant and thermal-insulating coating comprising porous ceramic additives, modified epoxy resin, modified acrylic resin, and amino resin, and a production method thereof. The water-based coating prepared by this method does not volatilize organic solvents during the coating preparation process, but because the system contains multiple resins with significantly different physical properties, the prepared coating has poor uniformity and is prone to cracking and falling off under repeated temperature changes.

[0008] CN201110307861.0 relates to a low-thermal-conductivity composite insulation coating and its preparation method. This method involves adding various additives, pigments, aerogels, and hollow glass microspheres to a phenolic epoxy resin solution and uniformly dispersing the mixture to produce the low-thermal-conductivity composite insulation coating. While the low-thermal-conductivity composite insulation coating produced by this method can achieve a thermal conductivity of 0.04 W / m·K, it still fails to achieve stable adhesion between the coating and the substrate under variable temperature conditions.

[0009] CN202110923268.2 relates to nano thermal insulation coatings, preparation methods and preparation equipment. The technical solution involved in this patent application uses pure acrylic emulsion and white cement as binders, and adds other additives and thermal insulation materials to make water-based coatings. Since the coating prepared by this coating uses a large amount of cement with a large thermal conductivity coefficient, its thermal insulation effect needs to be further improved, and the bonding stability also needs to be further improved.

[0010] In the above formulation, the physical properties between the coating and the tubing base are significantly different, but the bonding structure is primarily based on van der Waals forces, lacking the stronger and more stable chemical bonds. Frequent thermal expansion and contraction at high and low temperatures can easily cause cracking at the van der Waals interface, resulting in a shorter lifespan and poorer stability for the insulation coating or material. Summary of the Invention

[0011] In order to solve the above problems, the purpose of the present invention is to provide an anti-corrosion and thermal insulation coating for oil pipes and its preparation process. The coating constructs a transition layer that has both anti-corrosion and connection functions. The main coating and the metal substrate are connected through the transition layer. Therefore, it can maintain good stability under variable temperature conditions and greatly improve the service life of the coating.

[0012] To achieve the above object, the present invention provides a process for preparing an anti-corrosion and thermal insulation coating for oil pipes, which comprises the following steps:

[0013] (1) forming a coupling agent layer on the outer wall surface of the oil pipe;

[0014] (2) forming a polyaniline layer on the surface of the coupling agent layer;

[0015] (3) An outer coating with anti-corrosion and heat-insulating properties is formed on the surface of the polyaniline layer.

[0016] In the above preparation process, preferably, in step (1), the coupling agent is one or a combination of two or more of phenyltrimethoxysilane, anilinemethyltrimethoxysilane, phenyltriethoxysilane and anilinemethyltriethoxysilane.

[0017] In the above preparation process, preferably, in step (1), the coupling agent layer is formed by spraying coupling agent solution A.

[0018] In the above preparation process, preferably, the coupling agent concentration of the coupling agent solution A is 0.2 wt%-10 wt%.

[0019] In the above preparation process, preferably, the solvent of the coupling agent solution A is a mixture of ethanol and concentrated hydrochloric acid; more preferably, based on the mass of the mixture of ethanol and concentrated hydrochloric acid, the content of ethanol is 90-95%, the content of concentrated hydrochloric acid is 5-10%, and the concentration of concentrated hydrochloric acid is 37wt%.

[0020] In the above preparation process, preferably, the number of spraying is more than two times; more preferably, the spraying amount of each spraying is 10-100g / m 2 .

[0021] In the above preparation process, preferably, in step (2), the polyaniline layer is formed by spraying aniline solution B and ammonium persulfate solution C; more preferably, aniline solution B is sprayed first, followed by ammonium persulfate solution C. The polyaniline layer can serve as a transition layer between the outer coating (i.e., the main coating) and the oil pipe substrate.

[0022] In the above preparation process, preferably, the aniline concentration in the aniline solution B is 30 wt%-70 wt%.

[0023] In the above preparation process, preferably, the solvent of the aniline solution B is ethanol.

[0024] In the above preparation process, preferably, the ammonium persulfate concentration of the ammonium persulfate solution C is 5 wt%-20 wt%.

[0025] In the above preparation process, preferably, the pH value of the ammonium persulfate solution C is 2-6. The pH is preferably adjusted using sulfuric acid.

[0026] In the above preparation process, preferably, the solvent of the ammonium persulfate solution C is water.

[0027] In the above preparation process, preferably, the spraying amount of the aniline solution B is 1-50 g / m 2 The spraying amount of the ammonium persulfate solution C is 10-100g / m 2 .

[0028] In the above preparation process, preferably, in step (3), the outer coating is formed by spraying a coating G, and the raw materials of the coating G include a phenolic epoxy resin, a solvent, a thermal insulation filler, a reinforcing filler, a curing agent, a defoaming agent, and a leveling agent;

[0029] Wherein, the mass ratio of the phenolic epoxy resin to the solvent is 100:20-200;

[0030] The mass ratio of the phenolic epoxy resin to the thermal insulation filler is 100:5-30, preferably 100:5-20;

[0031] The mass ratio of the phenolic epoxy resin to the reinforcing filler is 100:5-30;

[0032] The mass ratio of the phenolic epoxy resin to the curing agent is 100:20-50;

[0033] The mass ratio of the phenolic epoxy resin to the defoamer is 100:0.1-1;

[0034] The mass ratio of the phenolic epoxy resin to the leveling agent is 100:0.1-1.

[0035] In the above preparation process, preferably, the solvent includes one or a combination of two or more of toluene, acetone, ethyl acetate and butanone.

[0036] In the above preparation process, preferably, the thermal insulation filler includes one or a combination of two or more of porous silica nanoparticles (preferably, with a particle size of 5nm-20nm and a thermal conductivity of 0.009-0.012W / m·K), aerogel particles (preferably, with a particle size of 5μm-20μm and a thermal conductivity of 0.009-0.012W / m·K) and hollow glass microspheres (preferably, with a particle size of 30μm-60μm and a thermal conductivity of 0.003-0.01W / m·K).

[0037] In the above preparation process, preferably, the reinforcing filler includes one or a combination of two or more of mica powder, talc powder, alumina powder, calcium silicate powder and silicon micropowder; more preferably, the particle size of the reinforcing filler is 5 μm-40 μm.

[0038] In the above preparation process, preferably, the curing agent includes one or a combination of two or more of polyamide, cardanol and phenalkamine.

[0039] In the above preparation process, the defoaming agent preferably includes one or a combination of two or more of a natural oil defoaming agent, a polyether defoaming agent, a silicone defoaming agent, and a polyether-modified silicone defoaming agent. Defoaming agents are commonly used in the art, and those skilled in the art can select an appropriate defoaming agent as needed.

[0040] In the above preparation process, preferably, the leveling agent includes one or a combination of two or more of an organic silicon leveling agent, an acrylic leveling agent, and a fluorocarbon leveling agent. Leveling agents are commonly used in the art, and those skilled in the art can select a suitable defoaming agent as needed.

[0041] In the above preparation process, preferably, the coating is prepared by the following method:

[0042] The phenolic epoxy resin and the solvent are mixed and ball-milled to obtain a mixture D;

[0043] Adding a heat-insulating filler to the mixture D and ball milling the mixture to obtain a mixture E;

[0044] Adding a reinforcing filler to the mixture E and ball milling the mixture to obtain a mixture F;

[0045] A curing agent, a defoaming agent, and a leveling agent were added to the mixture F, and the mixture was ball-milled to obtain a coating G.

[0046] In the above preparation process, preferably, when preparing the outer coating, the spraying amount of the coating G is 0.2-1.0 kg / m 2 .

[0047] The present invention also provides an anti-corrosion and thermal insulation coating for oil pipes, which is prepared by the above-mentioned preparation process.

[0048] The anti-corrosion and thermal insulation coating for oil pipes and its preparation process provided by this invention create a transition layer that provides both corrosion protection and connection. The transition layer connects the main coating to the metal substrate, maintaining excellent stability under variable temperature conditions and significantly extending the coating's service life. Furthermore, the external thermal insulation coating on downhole oil pipes offers excellent thermal insulation, effectively preventing heat transfer and providing insulation. This effectively mitigates heat loss during crude oil lifting, thereby maintaining the temperature of the crude oil within the pipe, preventing wax precipitation, and ensuring normal oil well production.

[0049] The thermal insulation coating provided by the present invention has excellent adhesion and strong bonding strength, which can reach above 10MPa. It also has good impact resistance and can prevent the expansion and contraction of the substrate caused by cold / heat at different temperatures. The coating is pollution-free, safe and environmentally friendly. The downhole oil pipe has excellent chemical resistance and stable chemical properties and is not affected by acids, alkalis, and corrosive substances. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 is a schematic diagram of the mechanism of oil pipe surface modification (taking phenyltrimethoxysilane as an example).

[0051] FIG2 is a schematic diagram of the interaction mechanism between polyaniline and the modified oil pipe surface.

[0052] Figure 3 is a schematic diagram of the mechanism of polyaniline in various action forms on the surface of the oil pipe. DETAILED DESCRIPTION

[0053] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be understood as limiting the scope of implementation of the present invention.

[0054] The preparation process of the anti-corrosion and thermal insulation coating for oil pipes provided by the present invention can be carried out according to the following steps:

[0055] First, prepare a transition layer with anti-corrosion properties:

[0056] 1. Clean the outer surface of the oil pipe;

[0057] 2. Dissolve the coupling agent in a mixture of ethanol and concentrated hydrochloric acid (concentration 37 wt%) (the mass ratio of ethanol to concentrated hydrochloric acid is 95:5) to obtain solution A. The concentration of the coupling agent is controlled between 0.2% and 10%;

[0058] 3. Spray solution A on the outer wall of the oil pipe twice, with a spraying amount of 10-100g / m 2 After each spraying, let it air dry for 12 hours, and finally rinse it with tap water and dry it to form a coupling agent layer. The principle of oil pipe surface modification is shown in Figure 1 (taking phenyltrimethoxysilane as an example);

[0059] 4. Dissolve aniline in ethanol to obtain solution B, wherein the concentration of aniline is controlled at 30%-70%;

[0060] 5. Continue to spray solution B on the surface of the coupling agent layer on the outer wall of the oil pipe to form an aniline layer. The spraying amount is 1-50g / m 2 ;

[0061] 6. Dissolve ammonium persulfate in water to obtain solution C. The concentration of ammonium persulfate is controlled between 5% and 20%. Adjust the pH of solution C to between 2 and 6 with sulfuric acid.

[0062] 7. 10 minutes after solution B is sprayed, spray solution C on the aniline layer on the outer wall of the oil pipe. The spraying amount is 10-100g / m 2 After spraying, let it stand for 5 hours, then rinse the outer wall of the oil pipe with water to obtain a polyaniline layer on the outer wall of the oil pipe.

[0063] On the one hand, the lone electron pairs on the central nitrogen atom in the polyaniline structure pair with the d electron orbitals of the metal Fe atoms, forming coordinated covalent bonds. This inactivates the Fe on the tubing surface, significantly reducing the metal's corrosion rate and providing corrosion inhibition. On the other hand, strong π-π interactions exist between the benzene rings in the resulting polyaniline layer and those on the modified tubing surface. The mechanism is illustrated in Figure 2, resulting in strong adhesion between the polyaniline layer and the metal substrate.

[0064] Secondly, prepare the outer coating with anti-corrosion and thermal insulation properties:

[0065] 1. Place a certain amount of phenolic epoxy resin in a ball mill, continue to add solvent, the ratio of phenolic epoxy resin to solvent is 100:20-200, and ball mill for 0.5-1 hour to obtain mixture D.

[0066] 2. Add fillers with good thermal insulation properties to mixture D. The mass ratio of phenolic epoxy resin to thermal insulation filler is 100:5-20. Ball mill for 0.5-1 hour to obtain mixture E.

[0067] 3. Continue to add reinforcing fillers to mixture E, with the mass ratio of phenolic epoxy resin to reinforcing fillers being 100:5-30, and ball mill for 0.5-1 h to obtain mixture F.

[0068] 4. Continue to add curing agent to mixture F, the mass ratio between phenolic epoxy resin and curing agent is 100:20-50; further add defoamer and leveling agent, the mass ratio between phenolic epoxy and the above-mentioned additives (defoamer, leveling agent) is 100:0.1-1, ball mill for 1-2 hours to obtain the final coating G.

[0069] 5. Spray coating G on the surface of the modified oil pipe at a spraying rate of 0.2-1.0kg / m 2 , and cured at 80°C for 1h to obtain an integrated anti-corrosion and thermal insulation coating. There is a strong interaction between the coating and the substrate, and the mechanism is shown in Figure 3.

[0070] Example 1

[0071] This embodiment provides a preparation process for an anti-corrosion and thermal insulation coating for an oil pipe, which includes the following steps:

[0072] Clean the outer wall of the oil pipe and dissolve the coupling agent phenyltrimethoxysilane in a mixture of ethanol and concentrated hydrochloric acid (the mass ratio of ethanol to concentrated hydrochloric acid is 95:5) to obtain solution A, in which the concentration of the coupling agent is 0.5%. Spray solution A twice on the outer wall of the oil pipe, with a spraying amount of 20g / m each time. 2 After each spraying, let it air dry for 12 hours, then rinse it with tap water and let it dry;

[0073] Aniline was dissolved in ethanol to obtain solution B, wherein the concentration of aniline was 40%. Solution B was sprayed on the outer wall of the oil pipe at a spraying amount of 20 g / m 2 ;

[0074] Dissolve ammonium persulfate in water to obtain solution C, with a concentration of 15%. Use sulfuric acid to adjust the pH of solution C to between 2 and 3. After solution B is sprayed for 10 minutes, continue to spray solution C on the outer wall surface of the oil pipe at a spraying amount of 40g / m 2After spraying, let it stand for 5 hours, then rinse the outer wall of the oil pipe with water to obtain a polyaniline layer on the outer wall of the oil pipe.

[0075] A certain amount of phenolic epoxy resin was placed in a ball mill, and solvent toluene was added thereto at a mass ratio of resin to solvent of 100:50, and the mixture was ball milled for 0.5 h to obtain mixture D; aerogel particles (particle size of 5 μm-20 μm, thermal conductivity of 0.009-0.012 W / m·K) were added to mixture D at a mass ratio of resin to the above filler of 100:10, and the mixture was ball milled for 0.5 h to obtain mixture E; reinforcing filler mica powder (particle size of 5 μm-40 μm) was added to mixture E at a mass ratio of resin to mica powder of 100:20, and the mixture was ball milled for 0.5 h to obtain mixture F; curing agent polyamide was added to mixture F at a mass ratio of resin to curing agent of 100:30; defoaming agent (natural oil) and leveling agent (silicone) were further added, and the mass ratio of resin to the above additives was 100:0.3, and the mixture was ball milled for 2 h to obtain the final coating G.

[0076] Spray coating G on the surface of the modified oil pipe. The spraying amount of coating G is 0.3kg / m 2 , and cured at 80℃ for 1h to obtain an integrated anti-corrosion and thermal insulation coating. There is a strong interaction between the coating and the substrate. The results of the coating test are shown in Table 1.

[0077] Thanks to the pre-designed transition layer, the coating maintained its highest adhesion standard of 5A after 10 high and low temperature cycles (according to CNCIA-HG / T0004-2012). Furthermore, salt spray testing demonstrated excellent corrosion resistance.

[0078] Table 1 Test results of coating of Example 1

[0079] Example 2

[0080] This embodiment provides a preparation process for an anti-corrosion and thermal insulation coating for an oil pipe, which includes the following steps:

[0081] Clean the outer surface of the oil pipe. Dissolve the coupling agent phenyltrimethoxysilane in a mixture of ethanol and concentrated hydrochloric acid (the mass ratio of ethanol to concentrated hydrochloric acid is 95:5) to obtain solution A, in which the concentration of the coupling agent is 1%. Spray solution A twice on the outer surface of the oil pipe, each spraying amount is 40g / m 2 After each spraying, let it air dry for 12 hours, then rinse it with tap water and let it dry;

[0082] Aniline was dissolved in ethanol to obtain solution B, in which the concentration of aniline was 50%; solution B was sprayed on the outer wall of the oil pipe at a spraying amount of 10 g / m 2 ;

[0083] Dissolve ammonium persulfate in water to obtain solution C, with a concentration of 10%. Use sulfuric acid to adjust the pH of solution C to between 3 and 4. After solution B is sprayed for 10 minutes, continue to spray solution C on the outer wall of the oil pipe at a spraying amount of 60g / m 2 After spraying, let it stand for 5 hours, then rinse the outer wall of the oil pipe with water to obtain a polyaniline layer on the outer wall of the oil pipe.

[0084] A certain amount of phenolic epoxy resin was placed in a ball mill, and solvent toluene was added thereto at a ratio of 100:70, and the mixture was ball milled for 1 hour to obtain a mixture D; hollow glass microspheres (particle size of 30 μm-60 μm, thermal conductivity of 0.003-0.01 W / m·K) were added to the mixture D, the mass ratio between the resin and the above filler was 100:15, and the mixture was ball milled for 1 hour to obtain a mixture E; reinforcing filler silicon micropowder (particle size of 5 μm-40 μm) was added to the mixture E, the mass ratio between the resin and the silicon micropowder was 100:15, and the mixture was ball milled for 0.5 hour to obtain a mixture F; curing agent cardanol was added to the mixture F, the mass ratio between the resin and the curing agent was 100:40; a defoamer (polyether) and a leveling agent (acrylate) were further added, the mass ratio between the resin and the above additives was 100:0.4, and the mixture was ball milled for 2 hours to obtain the final coating G.

[0085] Spray coating G on the surface of the modified oil pipe. The spraying amount of coating G is 0.5kg / m 2 , and cured at 80℃ for 1h to obtain an integrated anti-corrosion and thermal insulation coating. There is a strong interaction between the coating and the substrate. The results of the coating test are shown in Table 2.

[0086] Thanks to the pre-designed transition layer, the coating maintained its highest adhesion standard of 5A after 10 high and low temperature cycles (according to CNCIA-HG / T0004-2012). Furthermore, salt spray testing demonstrated excellent corrosion resistance.

[0087] Table 2 Test results of coating of Example 2

[0088] Example 3

[0089] This embodiment provides a preparation process for an anti-corrosion and thermal insulation coating for an oil pipe, which includes the following steps:

[0090] Clean the outer surface of the oil pipe. Dissolve the coupling agent phenyltrimethoxysilane in a mixture of ethanol and concentrated hydrochloric acid (the mass ratio of ethanol and concentrated hydrochloric acid is 95:5) to obtain solution A, in which the concentration of the coupling agent is 2%; spray solution A twice on the outer surface of the oil pipe, each spraying amount is 30g / m 2 After each spraying, let it dry naturally for 12 hours, then rinse it with tap water and let it dry.

[0091] Aniline was dissolved in ethanol to obtain solution B, in which the concentration of aniline was 50%. Solution B was sprayed on the outer wall of the oil pipe at a spraying amount of 30 g / m 2 ;

[0092] Dissolve ammonium persulfate in water to obtain solution C, with a concentration of 20%. Use sulfuric acid to adjust the pH of solution C to between 3 and 4. After solution B is sprayed for 10 minutes, continue to spray solution C on the outer wall of the oil pipe at a spraying amount of 100g / m 2 After spraying, let it stand for 5 hours, then rinse the outer wall of the oil pipe with water to obtain a polyaniline layer on the outer wall of the oil pipe.

[0093] A certain amount of phenolic epoxy resin was placed in a ball mill, and solvent toluene was added thereto in a ratio of 100:100, and ball milling was carried out for 0.8 h to obtain a mixture D. Hollow glass microspheres (particle size of 30 μm-60 μm, thermal conductivity of 0.003-0.01 W / m·K) and porous silica nanoparticles (particle size of 5 nm-20 nm, thermal conductivity of 0.009-0.012 W / m·K) were added to the mixture D in a mass ratio of 100:10:10 to the resin and the two fillers. Grind for 1 hour to obtain mixture E; continue to add reinforcing filler alumina powder (particle size: 5μm-40μm) to mixture E, the mass ratio between the resin and the alumina powder is 100:10, and ball mill for 0.5h to obtain mixture F; continue to add curing agent phenolic amine to mixture F, the mass ratio between the resin and the curing agent is 100:35; further add defoaming agent (silicone) and leveling agent (50% each of silicone and acrylate), the mass ratio between the resin and the above-mentioned additives is 100:0.5, and ball mill for 2h to obtain the final coating G.

[0094] Spray coating G on the surface of the modified oil pipe. The spraying amount of coating G is 0.8kg / m 2 , and cured at 80℃ for 1h to obtain an integrated anti-corrosion and thermal insulation coating. There is a strong interaction between the coating and the substrate. The results of the coating test are shown in Table 3.

[0095] Thanks to the pre-designed transition layer, the coating maintained its highest adhesion standard of 5A after 10 high and low temperature cycles (according to CNCIA-HG / T0004-2012). Furthermore, salt spray testing demonstrated excellent corrosion resistance.

[0096] Table 3 Test results of coating of Example 3

[0097] Example 4

[0098] This embodiment provides a preparation process for an anti-corrosion and thermal insulation coating for an oil pipe, which includes the following steps:

[0099] Clean the outer surface of the oil pipe; dissolve the coupling agent phenyltrimethoxysilane in a mixture of ethanol and concentrated hydrochloric acid (the mass ratio of ethanol to concentrated hydrochloric acid is 95:5) to obtain solution A, in which the concentration of the coupling agent is 4%; spray solution A twice on the outer surface of the oil pipe, each spraying amount is 60g / m 2 After each spraying, let it air dry for 12 hours, then rinse it with tap water and let it dry;

[0100] Aniline was dissolved in ethanol to obtain solution B, in which the concentration of aniline was 60%; solution B was sprayed on the outer wall of the oil pipe at a spraying amount of 40 g / m 2 ;

[0101] Dissolve ammonium persulfate in water to obtain solution C, with a concentration of 15%. Use sulfuric acid to adjust the pH of solution C to between 4 and 5. After solution B is sprayed for 10 minutes, continue to spray solution C on the outer wall of the oil pipe at a spraying amount of 90g / m 2 After spraying, let it stand for 5 hours, then rinse the outer wall of the oil pipe with water to obtain a polyaniline layer on the outer wall of the oil pipe.

[0102] A certain amount of phenolic epoxy resin was placed in a ball mill, and solvent toluene was added thereto at a ratio of resin to solvent of 100:150, and the mixture was ball milled for 0.5 h to obtain a mixture D. Aerogel particles (particle size of 5 μm-20 μm, thermal conductivity of 0.009-0.012 W / m·K) and porous silica nanoparticles (particle size of 5 nm-20 nm, thermal conductivity of 0.009-0.012 W / m·K) were added to the mixture D at a mass ratio of resin to the above two fillers of 100:15:10, and the mixture was ball milled for 0.5 h. 0.8 hours to obtain mixture E; alumina powder (particle size 5-40 μm) as a reinforcing filler was further added to mixture E, with the mass ratio of resin to alumina powder being 100:15. The mixture was ball-milled for 1 hour to obtain mixture F; phenalkamine and cardanol as curing agents were further added to mixture F, with the mass ratio of resin to both curing agents being 100:20:20. A defoamer (polyether-modified silicone) and a leveling agent (50% each of acrylate and fluorocarbon) were further added, with the mass ratio of resin to these additives being 100:0.6. The mixture was ball-milled for 2 hours to obtain the final coating G.

[0103] Spray coating G on the surface of the modified oil pipe. The spraying amount of coating G is 0.4kg / m 2 , and cured at 80℃ for 1h to obtain an integrated anti-corrosion and thermal insulation coating. There is a strong interaction between the coating and the substrate. The results of the coating test are shown in Table 4.

[0104] Thanks to the pre-designed transition layer, the coating maintained its highest adhesion standard of 5A after 10 high and low temperature cycles (according to CNCIA-HG / T0004-2012). Furthermore, salt spray testing demonstrated excellent corrosion resistance.

[0105] Table 4 Test results of coating of Example 4

[0106] Example 5

[0107] This embodiment provides a preparation process for an anti-corrosion and thermal insulation coating for an oil pipe, which includes the following steps:

[0108] Clean the outer surface of the oil pipe; dissolve the coupling agent phenyltrimethoxysilane in a mixture of ethanol and concentrated hydrochloric acid (the mass ratio of ethanol to concentrated hydrochloric acid is 95:5) to obtain solution A, in which the concentration of the coupling agent is 8%; spray solution A twice on the outer surface of the oil pipe, each spraying amount is 80g / m 2 After each spraying, let it air dry for 12 hours, then rinse it with tap water and let it dry;

[0109] Aniline was dissolved in ethanol to obtain solution B, in which the concentration of aniline was 70%. Solution B was sprayed on the outer wall of the oil pipe at a spraying amount of 50 g / m 2 ;

[0110] Dissolve ammonium persulfate in water to obtain solution C, with a concentration of 20%. Use sulfuric acid to adjust the pH of solution C to between 3 and 4. After solution B is sprayed for 10 minutes, continue to spray solution C on the outer wall of the oil pipe at a spraying amount of 95g / m 2 After spraying, let it stand for 5 hours, then rinse the outer wall of the oil pipe with water to obtain a polyaniline layer on the outer wall of the oil pipe.

[0111] A certain amount of phenolic epoxy resin was placed in a ball mill, and solvent toluene was added thereto at a ratio of 100:200, and ball milling was performed for 1 hour to obtain a mixture D. Porous silica nanoparticles (particle size of 5 nm-20 nm, thermal conductivity of 0.009-0.012 W / m·K) were added to the mixture D at a mass ratio of 100:15 between the resin and the filler, and ball milling was performed for 1 hour to obtain a mixture E. Talc powder, a reinforcing filler, was further added to the mixture E. (particle size is 5μm-40μm), the mass ratio between the resin and talc is 100:20, and ball milling is carried out for 0.5h to obtain a mixture F; further add curing agent polyamide and cardanol to the mixture F, and the mass ratio between the resin and the two curing agents is 100:15:20; further add a defoaming agent (50% each of polyether and silicone) and a leveling agent (fluorocarbon compound), and the mass ratio between the resin and the above-mentioned additives is 100:0.8, and ball milling is carried out for 2h to obtain the final coating G.

[0112] Spray coating G on the surface of the modified oil pipe. The spraying amount of coating G is 0.6kg / m 2 , and cured at 80℃ for 1h to obtain an integrated anti-corrosion and thermal insulation coating. There is a strong interaction between the coating and the substrate. The results of the coating test are shown in Table 5.

[0113] Table 5 Test results of coating of Example 5

[0114] Thanks to the pre-designed transition layer, the coating maintained its highest adhesion standard of 5A after 10 high and low temperature cycles (according to CNCIA-HG / T0004-2012). Furthermore, salt spray testing demonstrated excellent corrosion resistance.

[0115] Example 6

[0116] This embodiment provides a preparation process for an anti-corrosion and thermal insulation coating for an oil pipe, which includes the following steps:

[0117] Clean the outer surface of the oil pipe; dissolve the coupling agent phenyltrimethoxysilane in a mixture of ethanol and concentrated hydrochloric acid (the mass ratio of ethanol to concentrated hydrochloric acid is 95:5) to obtain solution A, in which the concentration of the coupling agent is 7%; spray solution A twice on the outer surface of the oil pipe, each spraying amount is 90g / m 2 After each spraying, let it air dry for 12 hours, then rinse it with tap water and let it dry;

[0118] Aniline was dissolved in ethanol to obtain solution B, in which the concentration of aniline was 65%. Solution B was sprayed on the outer wall of the oil pipe at a spraying amount of 35 g / m 2 ;

[0119] Dissolve ammonium persulfate in water to obtain solution C, with a concentration of 18%. Use sulfuric acid to adjust the pH of solution C to between 3 and 4. After solution B is sprayed for 10 minutes, continue to spray solution C on the outer wall of the oil pipe at a spraying amount of 75g / m 2 After spraying, let it stand for 5 hours, then rinse the outer wall of the oil pipe with water to obtain a polyaniline layer on the outer wall of the oil pipe.

[0120] A certain amount of phenolic epoxy resin was placed in a ball mill, and solvent toluene was added thereto, with the ratio of resin to solvent being 100:130, and ball milling was performed for 1 hour to obtain mixture D; porous silica nanoparticles were added to mixture D, with the mass ratio between the resin and the above filler being 100:15, and ball milling was performed for 1 hour to obtain mixture E; reinforcing filler calcium silicate powder was added to mixture E, with the mass ratio between the resin and calcium silicate powder being 100:18, and ball milling was performed for 0.5 hour to obtain mixture F; curing agent polyamide was added to mixture F, with the mass ratio between the resin and the curing agent being 100:35; defoaming agent (organic silicone) and leveling agent (fluorocarbon compound) were further added, with the mass ratio between the resin and the above additives being 100:0.7, and ball milling was performed for 2 hours to obtain the final coating G.

[0121] Spray coating G on the surface of the modified oil pipe. The spraying amount of coating G is 0.55kg / m 2 , and cured at 80℃ for 1h to obtain an integrated anti-corrosion and thermal insulation coating. There is a strong interaction between the coating and the substrate. The results of the coating test are shown in Table 6.

[0122] Thanks to the pre-designed transition layer, the coating maintained its highest adhesion standard of 5A after 10 high and low temperature cycles (according to CNCIA-HG / T0004-2012). Furthermore, salt spray testing demonstrated excellent corrosion resistance.

[0123] Table 6 Test results of coating of Example 6

[0124] Example 7

[0125] This embodiment provides a preparation process for an anti-corrosion and thermal insulation coating for an oil pipe, which includes the following steps:

[0126] Clean the outer surface of the oil pipe; dissolve the coupling agent phenyltrimethoxysilane in a mixture of ethanol and concentrated hydrochloric acid (the mass ratio of ethanol to concentrated hydrochloric acid is 95:5) to obtain solution A, in which the concentration of the coupling agent is 10%; spray solution A twice on the outer surface of the oil pipe, each spraying amount is 90g / m 2 After each spraying, let it air dry for 12 hours, then rinse it with tap water and let it dry;

[0127] Aniline was dissolved in ethanol to obtain solution B, in which the concentration of aniline was 35%. Solution B was sprayed on the outer wall of the oil pipe at a spraying amount of 18 g / m 2 ;

[0128] Dissolve ammonium persulfate in water to obtain solution C, with a concentration of 11%. Use sulfuric acid to adjust the pH of solution C to between 4 and 6. After solution B is sprayed for 10 minutes, continue to spray solution C on the outer wall of the oil pipe at a spraying amount of 45g / m 2 After spraying, let it stand for 5 hours, then rinse the outer wall of the oil pipe with water to obtain a polyaniline layer on the outer wall of the oil pipe.

[0129] A certain amount of phenolic epoxy resin was placed in a ball mill, and solvent toluene was added thereto, with the ratio of resin to solvent being 100:110, and ball milling was performed for 0.8 h to obtain mixture D; hollow glass microspheres were added to mixture D, with the mass ratio between the resin and the above fillers being 100:20, and ball milling was performed for 1 h to obtain mixture E; reinforcing fillers mica powder and calcium silicate powder were added to mixture E, with the mass ratio between the resin and the above two fillers being 100:10:5, and ball milling was performed for 0.5 h to obtain mixture F; curing agent phenolic amine was added to mixture F, with the mass ratio between the resin and the curing agent being 100:30; defoaming agent (organic silicone) and leveling agent (fluorocarbon compound) were further added, with the mass ratio between the resin and the above additives being 100:0.6, and ball milling was performed for 1.5 h to obtain the final coating G.

[0130] Spray coating G on the surface of the modified oil pipe. The spraying amount of coating G is 0.7kg / m 2 , and cured at 80℃ for 1h to obtain an integrated anti-corrosion and thermal insulation coating. There is a strong interaction between the coating and the substrate. The results of the coating test are shown in Table 7.

[0131] Table 7 Test results of coating of Example 7

[0132] Thanks to the pre-designed transition layer, the coating maintained its highest adhesion standard of 5A after 10 high and low temperature cycles (according to CNCIA-HG / T0004-2012). Furthermore, salt spray testing demonstrated excellent corrosion resistance.

Claims

1. A preparation process of an anti-corrosion and heat-insulating coating for oil pipes, which comprises the following steps: (1) Form a coupling agent layer on the outer wall surface of the oil pipe; (2) Form a polyaniline layer on the surface of the coupling agent layer; (3) Form an outer coating with anti-corrosion and heat-insulating properties on the surface of the polyaniline layer.

2. The preparation process according to claim 1, wherein, In step (1), the coupling agent is one or a combination of two or more of phenyltrimethoxysilane, anilinomethyltrimethoxysilane, phenyltriethoxysilane, and anilinomethyltriethoxysilane.

3. The preparation process according to claim 1, wherein In step (1), the coupling agent layer is formed by spraying coupling agent solution A.

4. The preparation process according to claim 3, wherein, The coupling agent concentration of the coupling agent solution A is 0.2wt%-10wt%.

5. The preparation process according to claim 4, wherein, The solvent of the coupling agent solution A is a mixed solution of ethanol and concentrated hydrochloric acid.

6. The preparation process according to claim 5, wherein, Based on the mass of the mixed solution of ethanol and concentrated hydrochloric acid, the content of ethanol is 90-95%, the content of concentrated hydrochloric acid is 5-10%, and the concentration of concentrated hydrochloric acid is 37wt%.

7. The preparation process according to any one of claims 3-6, wherein, The number of sprayings is more than two times.

8. The preparation process according to claim 7, wherein, The spraying amount for each spraying is 10 - 100 g / m 2 .

9. The preparation process according to claim 1, wherein, In step (2), the polyaniline layer is formed by spraying aniline solution B and ammonium persulfate solution C.

10. The preparation process according to claim 9, wherein, First, spray aniline solution B, and then spray ammonium persulfate solution C.

11. The preparation process according to claim 9, wherein, The aniline concentration in the aniline solution B is 30wt%-70wt%.

12. The preparation process according to claim 9, wherein, The ammonium persulfate concentration of the ammonium persulfate solution C is 5wt%-20wt%.

13. The preparation process according to claim 12, wherein, The pH value of the ammonium persulfate solution C is 2-6.

14. The preparation process according to any one of claims 9-12, wherein, The spraying amount of the aniline solution B is 1 - 50 g / m 2 , and the spraying amount of the ammonium persulfate solution C is 10 - 100 g / m 2 .

15. The preparation process according to claim 1, wherein, In step (3), the outer coating is formed by spraying coating G, and the raw materials of the coating G include phenolic epoxy resin, solvent, heat-insulating filler, reinforcing filler, curing agent, defoaming agent, and leveling agent; Among them, the mass ratio of the phenolic epoxy resin to the solvent is 100:20-200; The mass ratio of the phenolic epoxy resin to the heat-insulating filler is 100:5-30; The mass ratio of the phenolic epoxy resin to the reinforcing filler is 100:5-30; The mass ratio of the phenolic epoxy resin to the curing agent is 100:20-50; The mass ratio of the phenolic epoxy resin to the defoaming agent is 100:0.1-1; The mass ratio of the phenolic epoxy resin to the leveling agent is 100:0.1-1.

16. The preparation process according to claim 15, wherein, The solvent includes one or a combination of two or more of toluene, acetone, ethyl acetate, and methyl ethyl ketone.

17. The preparation process according to claim 15, wherein, The heat-insulating filler includes one or a combination of two or more of porous silica nanoparticles, aerogel particles, and hollow glass microspheres.

18. The preparation process according to claim 17, wherein, The particle size of the porous silica nanoparticles is 5nm-20nm, and the thermal conductivity is 0.009-0.012W / m·K.

19. The preparation process according to claim 17, wherein, The particle size of the aerogel particles is 5μm-20μm, and the thermal conductivity is 0.009-0.012W / m·K.

20. The preparation process according to claim 17, wherein The particle size of the hollow glass microspheres is 30μm-60μm, and the thermal conductivity is 0.003-0.01W / m·K.

21. The preparation process according to claim 15, wherein, The reinforcing filler includes one or a combination of two or more of mica powder, talc powder, alumina powder, calcium silicate powder, and silica powder.

22. The preparation process according to claim 21, wherein, The particle size of the reinforcing filler is 5μm-40μm.

23. The preparation process according to claim 15, wherein, The curing agent includes one or a combination of two or more of polyamide, cardanol, and phenolic amine.

24. The preparation process according to claim 15, wherein, The coating is prepared by the following method: Mix the phenolic epoxy resin with a solvent and ball-mill to obtain mixture D; Add a heat-insulating filler to mixture D and ball-mill to obtain mixture E; Add a reinforcing filler to mixture E and ball-mill to obtain mixture F; Add a curing agent to mixture F, then add an antifoaming agent and a leveling agent, and ball-mill to obtain coating G.

25. The preparation process according to any one of claims 15-24, wherein, The spraying amount of the coating G is 0.2 - 1.0 kg / m 2 .

26. An anti-corrosion and heat-insulating coating for oil pipes, which is prepared by the preparation process described in any one of claims 1-25.

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