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

Abstract

The invention provides an anti-corrosion heat-preservation coating for an oil pipe and a preparation process of the anti-corrosion heat-preservation coating. The preparation process comprises the following steps: (1) forming a coupling agent layer on the surface of the outer wall of the oil pipe; (2) forming a polyaniline layer on the surface of the coupling agent layer; and (3) forming an outer coating with corrosion-resistant and heat-insulating properties on the surface of the polyaniline layer. The invention also provides the anti-corrosion thermal insulation coating for the oil pipe, which is prepared by the preparation process. According to the anti-corrosion heat-preservation coating for the oil pipe and the preparation process of the anti-corrosion heat-preservation coating, the transition layer with the anti-corrosion function and the connection function is built, the main coating and the metal base body are connected through the transition layer, and therefore good stability is kept under the variable-temperature condition, and the service life of the coating is greatly prolonged.

Description

Technical Field

[0001] The present invention belongs to the field of composite material preparation, and particularly relates to an anti-corrosion and heat-insulating coating for oil pipes and a preparation process thereof. Background Art

[0002] During the oil reservoir development process, crude oil flows from the oil layer into the bottom of the well and then is lifted from the bottom of the well to the wellhead along the wellbore. During the oil and gas lifting process, heat diffuses from the production oil pipe to the external annular area, resulting in a decrease in the temperature of the fluid inside the pipe, forming gas hydrates and wax deposits. Part of the wax crystals in the oil flow are produced with the oil flow, and part of them aggregate, condense and adhere to the metal surface of the oil well facilities, resulting in the wax blockage of the sucker rod pump and the oil pipe rod.

[0003] As described above, the wax formation in the oil wellbore is mainly caused by the temperature drop due to the heat dissipation of the pipe wall. In order to reduce the temperature loss of the oil pipe, an anti-corrosion and heat-insulating coating is applied on the outer wall of the oil pipe to prevent the wax formation in the wellbore during the crude oil production process and ensure the normal production to the greatest extent.

[0004] CN202111575170.9 relates to a method for oil production using a high-performance heat-insulating material to form an oil pipe heat-insulating system. This method first wraps a high-performance heat-insulating material outside the oil pipe, and then wraps a silica glass fiber cloth and a thin metal sealing pipe in sequence. The oil pipe prepared by this patent has good heat-insulating performance, but the preparation process is complex, and the thin metal sealing pipe is prone to corrosion during long-term use, resulting in a short service life.

[0005] CN201210172354.5 relates to an epoxy acrylic modified high anti-corrosion and heat-insulating coating containing porous ceramic additives and a production method thereof. The water-based coating prepared by this method has no solvent volatilization during the coating preparation process, but the prepared coating has poor uniformity and heat resistance, and is prone to peeling under repeated temperature changes.

[0006] CN201110307861.0 relates to a low thermal conductivity composite heat-insulating coating and a preparation method thereof. This method adds various additives, fillers, pigments and hollow glass microspheres to a phenolic epoxy resin solution, and the low thermal conductivity composite heat-insulating coating can be obtained after uniform dispersion. The thermal conductivity of the low thermal conductivity composite heat-insulating coating prepared by this method can reach 0.04 W / m·K, but this coating still does not solve the problem of stable bonding between the coating and the substrate under variable temperature conditions.

[0007] CN202110923268.2 relates to a nano heat-insulating coating, a preparation method and a preparation device thereof. The technical solution involved in this patent application uses pure acrylic emulsion and white cement as binders, and adds other additives and heat-insulating materials to make a water-based coating. The heat-insulating effect and bonding stability of the coating prepared by this coating need to be further improved.

[0008] None of the technical solutions involved in the above patent applications have solved the problem of the bonding stability between the coating thermal insulation material and the substrate under frequently changing temperature conditions, resulting in a short lifespan and poor stability of the thermal insulation coating or the thermal insulation material. Summary of the Invention

[0009] To solve the above problems, the purpose of the present invention is to provide an anti-corrosion and thermal insulation coating for oil pipelines and its preparation process. This coating constructs a layer that combines anti-corrosion and connection transition functions. The main coating is connected to the metal substrate through the transition layer, so it can maintain good stability under changing temperature conditions and greatly improve the service life of the coating.

[0010] To achieve the above purpose, the present invention provides a preparation process for an anti-corrosion and thermal insulation coating for oil pipelines, which includes the following steps:

[0011] (1) Form a coupling agent layer on the outer wall surface of the oil pipeline;

[0012] (2) Form a polyaniline layer on the surface of the coupling agent layer;

[0013] (3) Form an outer coating with anti-corrosion and thermal insulation properties on the surface of the polyaniline layer.

[0014] In the above preparation process, preferably, in step (1), the coupling agent is one or a combination of two or more of phenyltrimethoxysilane, anilinomethyltrimethoxysilane, phenyltriethoxysilane, and anilinomethyltriethoxysilane.

[0015] In the above preparation process, preferably, in step (1), the coupling agent layer is formed by spraying coupling agent solution A.

[0016] In the above preparation process, preferably, the coupling agent concentration of the coupling agent solution A is 0.2 wt% - 10 wt%.

[0017] In the above preparation process, preferably, the solvent of the coupling agent solution A is a mixed solution of ethanol and concentrated hydrochloric acid; more preferably, 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 the concentrated hydrochloric acid is 37 wt%.

[0018] In the above preparation process, preferably, the number of sprays is more than two; more preferably, the spraying amount for each spray is 10 - 100 g / m 2 .

[0019] 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, and then ammonium persulfate solution C is sprayed. This polyaniline layer can serve as a transition layer between the outer coating (i.e., the main coating) and the tubing matrix.

[0020] In the above preparation process, preferably, the aniline concentration in the aniline solution B is 30 wt% - 70 wt%.

[0021] In the above preparation process, preferably, the solvent of the aniline solution B is ethanol.

[0022] In the above preparation process, preferably, the ammonium persulfate concentration in the ammonium persulfate solution C is 5 wt% - 20 wt%.

[0023] In the above preparation process, preferably, the pH value of the ammonium persulfate solution C is 2 - 6. This pH is preferably adjusted with sulfuric acid.

[0024] In the above preparation process, preferably, the solvent of the ammonium persulfate solution C is water.

[0025] In the above preparation process, preferably, 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 .

[0026] In the above preparation process, preferably, 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 preservation filler, reinforcing filler, curing agent, defoaming agent, and leveling agent;

[0027] Among them, the mass ratio of the phenolic epoxy resin to the solvent is 100:20 - 200;

[0028] The mass ratio of the phenolic epoxy resin to the heat preservation filler is 100:5 - 20;

[0029] The mass ratio of the phenolic epoxy resin to the reinforcing filler is 100:5 - 30;

[0030] The mass ratio of the phenolic epoxy resin to the curing agent is 100:20 - 50;

[0031] The mass ratio of the phenolic epoxy resin to the defoaming agent is 100:0.1 - 1;

[0032] The mass ratio of the phenolic epoxy resin to the leveling agent is 100:0.1 - 1.

[0033] In the above preparation process, preferably, the solvent includes one or a combination of two or more of toluene, acetone, ethyl acetate, and methyl ethyl ketone.

[0034] In the above preparation process, preferably, the heat-insulating filler includes one or a combination of two or more of silica porous nanoparticles (preferably, with a particle size of 5 nm - 20 nm and a thermal conductivity of 0.009 - 0.012 W / m·K), aerogel particles (preferably, with a particle size of 5 μm - 20 μm and a thermal conductivity of 0.009 - 0.012 W / m·K), and hollow glass microspheres (preferably, with a particle size of 30 μm - 60 μm and a thermal conductivity of 0.003 - 0.01 W / m·K).

[0035] 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 silica powder; more preferably, the particle size of the reinforcing filler is 5 μm - 40 μm.

[0036] In the above preparation process, preferably, the curing agent includes one or a combination of two or more of polyamide, cardanol, and phenolic amine.

[0037] In the above preparation process, preferably, the defoamer includes one or a combination of two or more of natural oil defoamers, polyether defoamers, silicone defoamers, and polyether-modified silicone defoamers. Defoamers are common components in the art, and those skilled in the art can select appropriate defoamers according to needs.

[0038] In the above preparation process, preferably, the leveling agent includes one or a combination of two or more of silicone leveling agents, acrylate leveling agents, and fluorocarbon leveling agents. Leveling agents are common components in the art, and those skilled in the art can select appropriate defoamers according to needs.

[0039] In the above preparation process, preferably, the coating is prepared by the following method:

[0040] Mix and ball-mill phenolic epoxy resin with the solvent to obtain mixture D;

[0041] Add the heat-insulating filler to mixture D and ball-mill to obtain mixture E;

[0042] Add the reinforcing filler to mixture E and ball-mill to obtain mixture F;

[0043] Add the curing agent to mixture F, and then add the defoamer and leveling agent, and ball-mill to obtain coating G.

[0044] 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 .

[0045] The present invention also provides an anti-corrosion and heat-insulating coating for oil pipes, which is prepared by the above preparation process.

[0046] The anti-corrosion and heat-insulating coating for oil pipes provided by the present invention and its preparation process construct an anti-corrosion and connection transition layer. The main coating and the metal matrix are connected through the transition layer. Therefore, good stability is maintained under variable temperature conditions, and the service life of the coating is greatly improved. Description of the Drawings

[0047] Figure 1 Schematic diagram of the mechanism for the modification of the oil pipe surface (taking phenyltrimethoxysilane as an example).

[0048] Figure 2 Schematic diagram of the interaction mechanism between polyaniline and the modified oil pipe surface.

[0049] Figure 3 Pictures of the outer wall of the oil pipe and the outer wall of the oil pipe attached with polyaniline.

[0050] Figure 4 Schematic diagram of the mechanism of polyaniline with various action forms on the oil pipe surface. Detailed Embodiments

[0051] In order to have a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the technical solutions of the present invention are described in detail below, but it should not be construed as a limitation on the implementable scope of the present invention.

[0052] The preparation process of the anti-corrosion and heat-insulating coating for oil pipes provided by the present invention can be carried out according to the following steps:

[0053] First, prepare a transition layer with anti-corrosion performance:

[0054] 1. Clean the outer wall surface of the oil pipe;

[0055] 2. Dissolve the coupling agent in a mixed solution 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, and control the concentration of the coupling agent between 0.2% - 10%;

[0056] 3. Spray solution A on the outer wall surface of the oil pipe twice, with a spraying amount of 10 - 100 g / m 2 , and after each spraying, let it air-dry naturally for 12 hours. Finally, rinse it with tap water and dry it to form a coupling agent layer; the principle of the modification of the oil pipe surface is as Figure 1 shown (taking phenyltrimethoxysilane as an example);

[0057] 4. Dissolve aniline in ethanol to obtain Solution B, where the concentration of aniline is controlled at 30% - 70%.

[0058] 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, and the spraying amount is 1 - 50 g / m 2 ;

[0059] 6. Dissolve ammonium persulfate in water to obtain Solution C, where the concentration of ammonium persulfate is controlled between 5% - 20%, and adjust the pH of Solution C to between 2 - 6 with sulfuric acid;

[0060] 7. After 10 min of spraying Solution B, spray Solution C on the surface of the aniline layer on the outer wall of the oil pipe, and the spraying amount is 10 - 100 g / m 2 , and keep it still for 5 h after spraying. Then rinse the outer wall of the oil pipe with water, and a polyaniline layer is obtained on the outer wall of the oil pipe. On the one hand, the lone pair electrons on the central atom N in the polyaniline structure pair with the empty d electron orbitals on the metal Fe atom to form a coordination covalent bond, thereby passivating the Fe on the oil pipe surface and significantly reducing the metal corrosion rate to play a corrosion inhibition role. On the other hand, there is a strong π - π interaction between the benzene rings in the obtained polyaniline layer and the benzene rings on the modified oil pipe surface. The mechanism is as Figure 2 shown. Therefore, there is a strong adhesion force between the polyaniline layer and the metal matrix; the outer wall of the oil pipe after surface cleaning and the outer wall of the oil pipe with polyaniline attached are as Figure 3 shown.

[0061] Secondly, prepare an outer coating with anti - corrosion and heat - insulation properties:

[0062] 1. Place a certain amount of phenolic epoxy resin in a ball - milling tank, and continue to add a solvent to it. The ratio of phenolic epoxy resin to the solvent is 100:20 - 200, and ball - mill for 0.5 - 1 h to obtain Mixture D.

[0063] 2. Continue to add a heat - insulating filler to Mixture D. The mass ratio between phenolic epoxy resin and the heat - insulating filler is 100:5 - 20, and ball - mill for 0.5 - 1 h to obtain Mixture E.

[0064] 3. Continue to add a reinforcing filler to Mixture E. The mass ratio between phenolic epoxy resin and the reinforcing filler is 100:5 - 30, and ball - mill for 0.5 - 1 h to obtain Mixture F.

[0065] 4. Continue to add a curing agent to the mixture F. The mass ratio between the phenolic epoxy resin and the curing agent is 100:20 - 50. Further add an antifoaming agent and a leveling agent. The mass ratio between the phenolic epoxy and the above-mentioned auxiliaries (antifoaming agent, leveling agent) is 100:0.1 - 1. Ball mill for 1 - 2 h to obtain the final coating G.

[0066] 5. Spray the coating G on the surface of the surface-modified tubing. The spraying amount is 0.2 - 1.0 kg / m 2 , cure at 80 °C for 1 h to obtain a coating with integrated anti-corrosion and heat preservation. There is a strong interaction between the coating and the substrate. The mechanism is as Figure 4 shown.

[0067] Example 1

[0068] This example provides a preparation process for an anti-corrosion and heat-insulating coating for oil pipes, which includes the following steps:

[0069] Clean the outer wall surface of the oil pipe. Dissolve the coupling agent phenyltrimethoxysilane in a mixed solution of ethanol and concentrated hydrochloric acid (the mass ratio of ethanol to concentrated hydrochloric acid is 95:5) to obtain solution A. Among them, the concentration of the coupling agent is 0.5%. Spray solution A on the outer wall surface of the oil pipe twice, with a spraying amount of 20 g / m each time 2 , leave it to dry naturally for 12 hours after each spraying, and finally rinse it with tap water and then dry it;

[0070] Dissolve aniline in ethanol to obtain solution B. Among them, the concentration of aniline is 40%. Spray solution B on the outer wall surface of the oil pipe, with a spraying amount of 20 g / m 2 ;

[0071] Dissolve ammonium persulfate in water to obtain solution C. The concentration of ammonium persulfate is 15%. Adjust the pH of solution C to between 2 and 3 with sulfuric acid; 10 minutes after spraying solution B, continue to spray solution C on the outer wall surface of the oil pipe, with a spraying amount of 40 g / m 2 , let it stand for 5 h after spraying, and then rinse the outer wall of the oil pipe with water. A polyaniline layer is obtained on the outer wall of the oil pipe.

[0072] Place a certain amount of phenolic epoxy resin in a ball milling jar, and then add solvent toluene thereto. The mass ratio of the resin to the solvent is 100:50. Ball mill for 0.5 h to obtain mixture D; continue to add aerogel particles (particle size: 5 μm - 20 μm, thermal conductivity: 0.009 - 0.012 W / m·K) to mixture D. The mass ratio between the resin and the above-mentioned filler is 100:10. Ball mill for 0.5 h to obtain mixture E; continue to add reinforcing filler mica powder (particle size: 5 μm - 40 μm) to mixture E. The mass ratio between the resin and the mica powder is 100:20. Ball mill for 0.5 h to obtain mixture F; continue to add curing agent polyamide to mixture F. The mass ratio between the resin and the curing agent is 100:30; further add defoaming agent (natural oil type) and leveling agent (silicone type). The mass ratio between the resin and the above-mentioned additives is 100:0.3. Ball mill for 2 h to obtain the final coating G.

[0073] Spray coating G on the surface of the surface-modified oil pipe. The spraying amount of coating G is 0.3 kg / m 2 , and cure at 80 °C for 1 h to obtain an integrated anti-corrosion and heat-insulating coating. There is a strong interaction between the coating and the substrate. The test results of the coating are shown in Table 1.

[0074] Due to the presence of the pre-designed transition layer, after the coating undergoes 10 high-low temperature cycles (in accordance with CNCIA-HG / T0004-2012), the adhesion still reaches the highest standard of 5A. Moreover, through the salt spray test, it shows excellent corrosion resistance.

[0075] Table 1 Test results of the coating in Example 1

[0076] Test Items According to Standard Test Results Thermal Conductivity (W / m·K) GB / T 10294-2015 0.040 Surface Hardness (Shore D) GB / T 2411-2008 43 Adhesion SY / T 6717-2016 5A Impact Strength (J) SY / T 0315-2013 4.3 Salt Spray Resistance GB / T 1771-2007 No Blistering, No Rusting

[0077] Example 2

[0078] This example provides a preparation process for an anti-corrosion and heat-insulating coating for oil pipes, which includes the following steps:

[0079] Clean the outer wall surface of the oil pipe. Dissolve coupling agent phenyltrimethoxysilane in a mixed solution of ethanol and concentrated hydrochloric acid (mass ratio of ethanol to concentrated hydrochloric acid is 95:5) to obtain solution A, where the concentration of the coupling agent is 1%. Spray solution A on the outer wall surface of the oil pipe twice, with a spraying amount of 40 g / m each time 2 , and allow it to air dry naturally for 12 hours after each spraying. Finally, rinse it thoroughly with tap water and then dry it;

[0080] Dissolve aniline in ethanol to obtain solution B, where the concentration of aniline is 50%; spray solution B on the outer wall surface of the oil pipe, with a spraying amount of 10 g / m 2 ;

[0081] Dissolve ammonium persulfate in water to obtain solution C with a concentration of 10% ammonium persulfate, and adjust the pH of solution C to between 3 and 4 with sulfuric acid; 10 minutes after the spraying of solution B is completed, continue to spray solution C on the outer wall of the oil pipe with a spraying amount of 60 g / m 2 , and after the spraying is completed, let it stand for 5 h, then rinse the outer wall of the oil pipe with water, and a polyaniline layer is obtained on the outer wall of the oil pipe.

[0082] Place a certain amount of phenolic epoxy resin in a ball mill tank, and then add solvent toluene to it. The ratio of resin to solvent is 100:70, and ball mill for 1 h to obtain mixture D; continue to add hollow glass microspheres (with a particle size of 30 μm - 60 μm and a thermal conductivity of 0.003 - 0.01 W / m·K) to mixture D, and the mass ratio between the resin and the above-mentioned filler is 100:15, and ball mill for 1 h to obtain mixture E; continue to add reinforcing filler silica powder (with a particle size of 5 μm - 40 μm) to mixture E, and the mass ratio between the resin and silica powder is 100:15, and ball mill for 0.5 h to obtain mixture F; continue to add curing agent cardanol to mixture F, and the mass ratio between the resin and the curing agent is 100:40; further add defoaming agent (polyether type) and leveling agent (acrylate type), and the mass ratio between the resin and the above-mentioned additives is 100:0.4, and ball mill for 2 h to obtain the final coating G.

[0083] Spray coating G on the surface of the surface-modified oil pipe with a spraying amount of 0.5 kg / m 2 , and cure it at 80 °C for 1 h to obtain an integrated anti-corrosion and heat-insulating coating. There is a strong interaction between the coating and the substrate, and the test results of the coating are shown in Table 2.

[0084] Due to the presence of the pre-designed transition layer, after the coating undergoes 10 high-low temperature cycles (in accordance with CNCIA-HG / T0004-2012), the adhesion still reaches the highest standard of 5A. Moreover, through the salt spray test, it shows excellent corrosion resistance.

[0085] Table 2 Test results of the coating in Example 2

[0086]

[0087]

[0088] Example 3

[0089] This example provides a preparation process for an anti-corrosion and heat-insulating coating for oil pipes, which includes the following steps:

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

[0091] Dissolve aniline in ethanol to obtain solution B, where the concentration of aniline is 50%; spray solution B on the outer wall surface of the oil pipe, with a spraying amount of 30 g / m 2 ;

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

[0093] Place a certain amount of phenolic epoxy resin in a ball mill tank, and then add the solvent toluene to it. The ratio of resin to solvent is 100:100, and ball mill for 0.8 h to obtain mixture D; continue to add hollow glass microspheres (particle size: 30 μm - 60 μm, thermal conductivity: 0.003 - 0.01 W / m·K) and silica porous nanoparticles (particle size: 5 nm - 20 nm, thermal conductivity: 0.009 - 0.012 W / m·K) to mixture D. The mass ratio between the resin and the above two fillers is 100:10:10, and ball mill for 1 h to obtain mixture E; continue to add the reinforcing filler alumina powder (particle size: 5 μm - 40 μm) to mixture E. The mass ratio between the resin and alumina powder is 100:10, and ball mill for 0.5 h to obtain mixture F; continue to add the curing agent phenolic amine to mixture F. The mass ratio between the resin and the curing agent is 100:35; further add an antifoaming agent (silicone type) and a leveling agent (50% silicone and 50% acrylate type). The mass ratio between the resin and the above additives is 100:0.5, and ball mill for 2 h to obtain the final coating G.

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

[0095] Due to the presence of a pre-designed transition layer, after 10 high-low temperature cycles (in accordance with CNCIA-HG / T0004-2012), the adhesion of the coating still reached the highest standard of 5A. Moreover, through salt spray tests, it was shown that the corrosion resistance was excellent.

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

[0097] Test Items According to Standard Test Results Thermal Conductivity (W / m·K) GB / T 10294-2015 0.049 Surface Hardness (Shore D) GB / T 2411-2008 42 Adhesion SY / T 6717-2016 5A Impact Strength (J) SY / T 0315-2013 4.0 Salt Spray Resistance GB / T 1771-2007 No Blistering, No Rusting

[0098] Example 4

[0099] This example provides a preparation process for an anti-corrosion and heat-insulating coating for oil pipes, which includes the following steps:

[0100] Clean the outer wall surface of the oil pipe; dissolve the coupling agent phenyltrimethoxysilane in a mixed solution of ethanol and concentrated hydrochloric acid (the mass ratio of ethanol to concentrated hydrochloric acid is 95:5) to obtain Solution A, where the concentration of the coupling agent is 4%; spray Solution A on the outer wall surface of the oil pipe twice, with a spraying amount of 60 g / m 2 , and after each spraying, let it dry naturally for 12 hours, and finally rinse it thoroughly with tap water and then dry it;

[0101] Dissolve aniline in ethanol to obtain Solution B, where the concentration of aniline is 60%; spray Solution B on the outer wall surface of the oil pipe, with a spraying amount of 40 g / m 2 ;

[0102] Dissolve ammonium persulfate in water to obtain Solution C, with the concentration of ammonium persulfate being 15%, and adjust the pH of Solution C to between 4 and 5 with sulfuric acid; 10 minutes after spraying Solution B, continue to spray Solution C on the outer wall of the oil pipe, with a spraying amount of 90 g / m 2 , and after spraying, let it stand for 5 hours, and then rinse the outer wall of the oil pipe with water to obtain a polyaniline layer on the outer wall of the oil pipe.

[0103] Place a certain amount of phenolic epoxy resin in a ball mill jar, and then continue to add the solvent toluene into it. The ratio of the resin to the solvent is 100:150. Ball mill for 0.5 h to obtain mixture D; continue to add aerogel particles (particle size is 5 μm - 20 μm, thermal conductivity is 0.009 - 0.012 W / m·K) and silica porous nanoparticles (particle size is 5 nm - 20 nm, thermal conductivity is 0.009 - 0.012 W / m·K) into mixture D. The mass ratio between the resin and the above two fillers is 100:15:10. Ball mill for 0.8 h to obtain mixture E; continue to add reinforcing filler alumina powder (particle size is 5 μm - 40 μm) into mixture E. The mass ratio between the resin and the alumina powder is 100:15. Ball mill for 1 h to obtain mixture F; continue to add curing agents phenolic amine and cashew phenol into mixture F. The mass ratio between the resin and the two curing agents is 100:20:20; further add defoaming agent (polyether modified silicone type) and leveling agent (acrylate type and fluorocarbon type each 50%). The mass ratio between the resin and the above additives is 100:0.6. Ball mill for 2 h to obtain the final coating G.

[0104] Spray coating G on the surface of the surface-modified oil pipe. The spraying amount of coating G is 0.4 kg / m 2 , and cure at 80 °C for 1 h to obtain an integrated anti-corrosion and heat-insulating coating. There is a strong interaction between the coating and the substrate. The test results of the coating are shown in Table 4.

[0105] Due to the existence of the pre-designed transition layer, after the coating undergoes 10 high-low temperature cycles (in accordance with CNCIA-HG / T0004-2012), the adhesion still reaches the highest standard of 5A. Moreover, through the salt spray test, it shows excellent corrosion resistance.

[0106] Table 4 Test results of the coating in Example 4

[0107] Test Items According to Standard Test Results Thermal Conductivity (W / m·K) GB / T 10294-2015 0.081 Surface Hardness (Shore D) GB / T 2411-2008 41 Adhesion SY / T 6717-2016 5A Impact Strength (J) SY / T 0315-2013 4.5 Salt Spray Resistance GB / T 1771-2007 No Blistering, No Rusting

[0108] Example 5

[0109] This example provides a preparation process for an anti-corrosion and heat-insulating coating for oil pipes, which includes the following steps:

[0110] Clean the outer wall surface of the oil pipe; dissolve coupling agent phenyltrimethoxysilane in a mixed solution of ethanol and concentrated hydrochloric acid (the mass ratio of ethanol to concentrated hydrochloric acid is 95:5) to obtain solution A, where the concentration of the coupling agent is 8%; spray solution A on the outer wall surface of the oil pipe twice, with each spraying amount of 80 g / m 2 , and leave it to dry naturally for 12 hours after each spraying. Finally, rinse it with tap water and dry it.

[0111] Dissolve aniline in ethanol to obtain solution B, where the concentration of aniline is 70%. Spray solution B on the outer wall surface of the oil pipe, and the spraying amount is 50 g / m 2 ;

[0112] Dissolve ammonium persulfate in water to obtain solution C, where the concentration of ammonium persulfate is 20%, and adjust the pH of solution C to between 3 and 4 with sulfuric acid; 10 min after spraying solution B, continue to spray solution C on the outer wall of the oil pipe, and the spraying amount is 95 g / m 2 , and let it stand for 5 h after spraying. Then rinse the outer wall of the oil pipe with water, and a polyaniline layer is obtained on the outer wall of the oil pipe.

[0113] Place a certain amount of phenolic epoxy resin in a ball mill tank, and continue to add the solvent toluene to it. The ratio of resin to solvent is 100:200, and ball mill for 1 h to obtain mixture D; continue to add silica porous nanoparticles (particle size 5 nm - 20 nm, thermal conductivity 0.009 - 0.012 W / m·K) to mixture D, and the mass ratio between the resin and the above two fillers is 100:15, and ball mill for 1 h to obtain mixture E; continue to add reinforcing filler talc powder (particle size 5 μm - 40 μm) to mixture E, and the mass ratio between the resin and talc powder is 100:20, and ball mill for 0.5 h to obtain mixture F; continue to add curing agents polyamide and cashew phenol to mixture F, and the mass ratio between the resin and the two curing agents is 100:15:20; further add defoaming agents (50% each of polyether type and silicone type), leveling agents (fluorocarbon type), and the mass ratio between the resin and the above additives is 100:0.8, and ball mill for 2 h to obtain the final coating G.

[0114] Spray coating G on the surface of the surface-modified oil pipe, and the spraying amount of coating G is 0.6 kg / m 2 , and cure at 80°C for 1 h to obtain an integrated anti-corrosion and heat-insulating coating. There is a strong interaction between the coating and the substrate, and the test results of the coating are shown in Table 5.

[0115] Table 5 Test results of the coating in Example 5

[0116] Test Items According to Standard Test Results Thermal Conductivity (W / m·K) GB / T 10294-2015 0.038 Surface Hardness (Shore D) GB / T 2411-2008 44 Adhesion SY / T 6717-2016 5A Impact Strength (J) SY / T 0315-2013 4.4 Salt Spray Resistance GB / T 1771-2007 No Blistering, No Rusting

[0117] Due to the existence of the pre-designed transition layer, the adhesion of the coating still reaches the highest standard of 5A after 10 high-low temperature cycles (according to CNCIA-HG / T0004-2012). Moreover, through the salt spray test, it shows excellent corrosion resistance.

Claims

1. 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; preferably, 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 the concentrated hydrochloric acid is 37wt%.

6. The preparation process according to any one of claims 3-5, wherein, The number of sprayings is more than two times; preferably, the spraying amount for each spraying is 10 - 100 g / m 2 .

7. 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, preferably, spraying aniline solution B first and then spraying ammonium persulfate solution C.

8. The preparation process according to claim 7, wherein, The aniline concentration in the aniline solution B is 30wt%-70wt%.

9. The preparation process according to claim 7, wherein, The ammonium persulfate concentration of the ammonium persulfate solution C is 5wt%-20wt%.

10. According to the preparation process described in claim 9, wherein, The pH value of the ammonium persulfate solution C is 2-6.

11. The preparation process according to any one of claims 7-9, 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 .

12. 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 100:5-20; 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.

13. The preparation process according to claim 12, wherein, The solvent includes one or a combination of two or more of toluene, acetone, ethyl acetate, and methyl ethyl ketone.

14. The preparation process according to claim 12, wherein, The heat-insulating 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).

15. The preparation process according to claim 12, 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; preferably, the particle size of the reinforcing filler is 5μm-40μm.

16. The preparation process according to claim 12, wherein, The curing agent includes one or a combination of two or more of polyamide, cardanol, and phenolic amine.

17. The preparation process according to claim 12, 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 heat preservation filler to mixture D and ball mill to obtain mixture E; Add 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.

18. The preparation process according to any one of claims 12-17, wherein, The spraying amount of the coating G is 0.2 - 1.0 kg / m 2 .

19. An anti-corrosion and heat-insulating coating for oil pipes, which is prepared by the preparation process described in any one of claims 1-18.

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