A method for manufacturing a high-barrier steel-plastic composite pipe based on PEEK material

Abstract

The application discloses a kind of high barrier steel-plastic composite pipe manufacturing methods based on PEEK material, comprising the following steps: S1, steel pipe is removed dirt, by heating to remove the dirt impurities on the surface of steel pipe;S2, first PEEK raw material is treated with high temperature drying, and A product is obtained;S3, by high pressure extruder A product is extruded into the first mold, so that A product is continuously extruded on the outer surface of the steel pipe that moves at a constant speed in a molten state, A product and steel pipe are integrally continuously extruded into shape, and the steel pipe that is extruded on the steel pipe that moves at a constant speed is simultaneously rotated, so that A product is covered between steel pipe and forms spiral covering;A product covered steel-plastic composite pipe is obtained;S4, A product covered steel-plastic composite pipe is water-cooled, and then heated to remove stress;Recrystallization is completed simultaneously to obtain finished product. PEEK is used to coat the outer surface of the steel pipe, improve the barrier property, and protect the steel pipe from corrosion in extremely harsh environments.

Description

Technical Field

[0001] This invention relates to the field of composite material coating, specifically to a method for manufacturing a high-barrier steel-plastic composite pipe based on PEEK material. Background Technology

[0002] Plastic coating of steel pipes can improve their performance. For different environments, plastic coating has corresponding properties of composite materials, which can extend service life and adapt to harsher environments. Therefore, steel-plastic composite pipes are becoming increasingly popular. During the manufacturing process, a small amount of oil will adhere to the surface of the purchased steel pipes. Before plastic coating, the steel pipes need to be degreased by methods such as screw press, barrel, and heating.

[0003] During the surface treatment of steel pipes, although there is a process to remove oil stains, small solid particles may inevitably adhere to the surface of the steel pipe. Since the conventional plastic coating method involves axially covering the outer surface of the steel pipe with composite material, these small solid particles may tear small openings along the axial direction of the inner wall of the plastic coating film or create internal cracks along the impurities during the plastic coating process. Later, when the small openings or internal cracks left on the inner wall of the plastic coating film are subjected to stress concentration or external dust impact, the small openings enlarge, causing the plastic coating film to tear axially. Summary of the Invention

[0004] The purpose of this invention is to provide a method for manufacturing high-barrier steel-plastic composite pipes based on PEEK material, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for manufacturing a high-barrier steel-plastic composite pipe based on PEEK material includes the following steps:

[0007] S1. Degreasing steel pipes: removing oil and impurities from the surface of steel pipes by heating.

[0008] S2. First, the PEEK raw material is subjected to high-temperature drying treatment to obtain product A;

[0009] S3. The A product is extruded into the first mold through a high-pressure extruder, so that the A product is continuously extruded on the outer surface of the steel pipe that is moving axially at a uniform speed in a molten state. The A product and the steel pipe are continuously extruded as a whole. While the steel pipe is being extruded on the steel pipe that is moving axially at a uniform speed, the steel pipe is rotated, so that the A product and the steel pipe are spirally coated; thus, a steel-plastic composite pipe coated with the A product is obtained.

[0010] S4. After water cooling, the steel-plastic composite pipe coated with product A is heated to remove stress; at the same time, crystallization is completed to obtain the finished product.

[0011] Preferably, after step S4, there are also steps S5 and S6;

[0012] S5. Plasticize the PFA raw material to obtain product B, and extrude it into the second mold through a high-pressure extruder. Continuously spirally extrude the molten product B onto the plastic-coated steel pipe covered by product A which is moving axially at a uniform speed to obtain a double-layer steel-plastic composite pipe.

[0013] S6. After water cooling, the AB double-layer coated steel pipe is heated to remove stress and crystallize to obtain the finished product.

[0014] Preferably, product B is continuously spirally extruded, wherein the rotation direction is opposite to the spiral direction in step S3; product A is coated on the outer surface of the steel pipe, and product B is coated on the outer surface of product A; there is no gap between product A and product B.

[0015] Preferably, in step S1, the steel pipe is heated at a temperature of 140-160 degrees Celsius for 1-2 minutes.

[0016] Preferably, in step S4, water cooling and reheating are used to relieve stress and recrystallize simultaneously, with the reheating temperature at 200-250 degrees Celsius; in step S6, water cooling and reheating are used to relieve stress and recrystallize simultaneously, with the reheating temperature at 200-250 degrees Celsius; and in steps S4 and S6, the stress relief and recrystallization are performed together with the fixture.

[0017] Preferably, the PEEK film and PFA film coated on the outer surface of the steel pipe have different thicknesses: the PEEK film thickness is 0.2mm-0.25mm, and the PFA film thickness is 0.25mm-0.3mm. If the PEEK film thickness is less than 0.2mm, it will crack directly after water cooling and heating due to the material properties. If it is too thin, the yield will be low and the barrier effect will be poor. If the thickness is greater than 0.25mm, the barrier effect will be enhanced, but the heat transfer effect will be poor, resulting in the loss of heat exchange and energy-saving effects. Therefore, choosing 0.2mm-0.25mm is the most reasonable.

[0018] Preferably, the drying temperature of PEEK raw material is 150-160 degrees Celsius, and the drying time is 2-3 hours.

[0019] Preferably, in step S3, the high-pressure extruder applies an extrusion pressure between 70-140 MPa to product A, and the molten temperature of product A is maintained at 370-390 degrees Celsius; the molten product A is extruded into the first mold; the axial movement speed of product A is 0.7 m / min.

[0020] Preferably, in step S5, the high-pressure extruder applies a pressure of 20 MPa to product B and maintains the molten temperature of product B at 360-380 degrees Celsius, extruding the molten product B into the second mold, and the axial movement speed of product B is 0.7 m / min.

[0021] Preferably, in step S4, stress relief involves introducing cooling material into the cooling channel at a speed of 0.7 m / min. The cooling channel comprises a 150-200°C cooling section, a 50-100°C air-cooling section, and a room-temperature water-cooling section connected in sequence. The length of the cooling section is 3-4 meters, the length of the air-cooling section is 7-8 meters, and the length of the water-cooling section is 2-3 meters. In step S6, stress relief involves introducing cooling material into the cooling channel at a speed of 0.7 m / min. The cooling channel comprises a 150-200°C cooling section, a 50-100°C air-cooling section, and a room-temperature water-cooling section connected in sequence. The length of the cooling section is 3-4 meters, the length of the air-cooling section is 7-8 meters, and the length of the water-cooling section is 2-3 meters.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] This invention uses PEEK, a high-barrier material, to coat the outer surface of a steel pipe. PEEK is a special polymer material. PEEK has been used in aerospace, medical devices, and industrial fields. It has the characteristics of high temperature resistance, corrosion resistance, extrudability, and high mechanical strength, which can protect the steel pipe from corrosion in extremely harsh environments, prevent damage from the external environment, and improve the service life of the steel pipe.

[0024] The high shrinkage rate of PEEK material is compatible with the thermal expansion and contraction characteristics of steel pipe, avoiding the problem of PEEK material cracking when solidifying due to the small space for cooling and contraction of steel pipe. The spiral extrusion method changes the direction of the interaction of internal stresses in the material, preventing the PEEK material from cracking along the axial direction of the steel pipe after coating. It also makes the coating more uniform on the surface of the steel pipe, with better crystallization effect, and fully utilizes the characteristics of the material itself.

[0025] The double-layer coating method involves coating the steel pipe with PEEK material, followed by a layer of PFA material on the outer surface of the PEEK. This effectively combines the smooth properties of PFA material, making it less prone to dust accumulation on the steel pipe surface and enhancing the performance of the double coating. The PFA material is extruded in a spiral manner in the opposite direction to the PEEK material, resulting in more uniform stress and preventing cracking of the PFA material surface. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of axial tearing in a composite steel pipe.

[0027] Figure 2 This is a schematic diagram of the axial tear on the inner wall of the membrane.

[0028] Figure 3 This is a schematic diagram of PEEK spiral coating;

[0029] Figure 4This is a schematic diagram of PEEK spiral coating and PFA spiral coating.

[0030] In the diagram: 1. Composite steel pipe, 2. PEEK coating, 3. Small solid particles, 4. External force. Detailed Implementation

[0031] Example 1:

[0032] This invention provides a technical solution: a method for manufacturing a high-barrier steel-plastic composite pipe based on PEEK material, characterized by the following steps:

[0033] S1. Degreasing steel pipes: The steel pipes have a diameter of 20mm and a thickness of 1mm. The steel pipes are heated to remove oil and impurities from their surface, keeping the surface clean.

[0034] S2. First, the PEEK raw material is dried at a temperature of 150 degrees Celsius for 3 hours to obtain product A.

[0035] S3. The A product is extruded into the first mold through a high-pressure extruder, so that the A product is continuously extruded on the outer surface of the steel pipe that is moving axially at a uniform speed in a molten state. The A product and the steel pipe are continuously extruded as a whole. While the steel pipe is being extruded on the steel pipe that is moving axially at a uniform speed, the steel pipe is rotated, so that the A product and the steel pipe are spirally coated; thus, a steel-plastic composite pipe coated with the A product is obtained.

[0036] S4. After water cooling, the steel-plastic composite pipe coated with product A is heated to remove stress; at the same time, recrystallization is carried out to obtain the finished product.

[0037] Specifically, after step S4, there are also steps S5 and S6;

[0038] S5. The PFA raw material is dried to obtain product B, which is then extruded into the second mold through a high-pressure extruder. The molten product B is continuously spirally extruded onto the steel-plastic composite pipe covered by product A, which is moving axially at a uniform speed, to obtain a steel-plastic composite pipe with double-layer AB coating.

[0039] S6. After water cooling, the steel-plastic composite pipe with double AB coating is heated to remove stress; at the same time, recrystallization is obtained to obtain the finished product.

[0040] Specifically, product A is wrapped around the outer surface of the steel pipe, and product B is wrapped around the outer surface of product A; there is no gap between product A and product B.

[0041] Specifically, in step S4, water cooling and reheating relieve stress while recrystallizing, and the reheating temperature is 200-250 degrees Celsius; in step S6, water cooling and reheating relieve stress while recrystallizing, and the reheating temperature is 200-250 degrees Celsius. During the reheating and recrystallization in steps S4 and S6, the steel pipe is heated together with the fixture. If the position where the fixture clamps the steel pipe is heated differently from other positions, resulting in uneven crystallization, it will affect the crystallization effect.

[0042] Specifically, the PEEK and PFA films coated on the outer surface of steel pipes have different thicknesses: PEEK film is 0.2mm thick, while PFA film is 0.25mm thick. If the PEEK film thickness is less than 0.2mm, due to material properties, it will crack directly after water cooling and heating, resulting in a low yield and poor barrier properties. While a thickness greater than 0.25mm enhances the barrier effect, it reduces heat transfer, leading to a loss of heat exchange and energy-saving benefits. The PFA film thickness can be less than that of PEEK. The PFA membrane has excellent smoothness and can reduce the impact of external dust on the PEEK membrane when coated on the outer surface. It is sufficient to ensure that the PFA membrane has a good smoothness. If only one layer of PEEK membrane is used for coating, the lack of PFA membrane protection necessitates increasing the thickness of the PEEK membrane to improve the performance of the steel pipe. The PEEK membrane thickness is 0.25mm. If the PEEK membrane thickness is greater than 0.25mm, it increases the cost burden; if the PEEK membrane thickness is less than 0.25mm, the barrier effect will be reduced.

[0043] Specifically, in step S3, the high-pressure extruder applies an extrusion pressure of 70 MPa to product A, and the molten state temperature of product A is maintained at 380 degrees Celsius. At this temperature, product A in the molten state has a certain fluidity and viscosity, and can coat the steel pipe without slipping. The molten product A is extruded into the first mold. The axial movement speed of product A is 0.7 meters / minute.

[0044] PEEK material has a high shrinkage rate. PEEK material in a molten state is coated on the outer surface of the expanded steel pipe. Taking advantage of the thermal expansion and contraction of the steel pipe, the steel pipe expands when heated, coating the plasticized PEEK material on the surface of the steel pipe. After the steel pipe cools and shrinks, it provides sufficient space for the molten PEEK material to shrink, preventing the PEEK material from cracking after solidification.

[0045] Specifically, in step S5, the high-pressure extruder applies a pressure of 20 MPa to product B and maintains the molten state temperature of product B at 380 degrees Celsius. The molten product B is then extruded into the second mold, and the axial movement speed of product B is 0.7 m / min.

[0046] Specifically, in step S4, stress relief involves introducing cooling material into the cooling channel at a speed of 0.7 m / min. The cooling channel comprises a 150°C cooling section, an 80°C air-cooled section, and a room-temperature water-cooled section connected in sequence. The length of the cooling section is 3 meters, the length of the air-cooled section is 7 meters, and the length of the water-cooled section is 2 meters. In step S6, stress relief involves introducing cooling material into the cooling channel at a speed of 0.7 m / min. The cooling channel comprises a 150°C cooling section, an 80°C air-cooled section, and a room-temperature water-cooled section connected in sequence. The length of the cooling section is 3 meters, the length of the air-cooled section is 7 meters, and the length of the water-cooled section is 2 meters.

[0047] Working principle:

[0048] refer to Figure 1-2 In conventional plastic coating methods, the axial direction of the composite steel pipe 1 is the same as that of the PEEK coating film 2. Inevitably, some small solid particles 3 will remain on the outer surface of the composite steel-plastic pipe. During the coating process, when the PEEK coating film 2 is applied axially, the small solid particles 3 will obstruct the coating, leaving tiny tears at these points on the inner wall of the PEEK coating film 2. Later, under the impact of external forces 4 such as dust or knocking, coupled with the internal stress of the PEEK coating film 2, axial tearing will occur, affecting the barrier effect.

[0049] refer to Figure 3 Therefore, in order to avoid axial tearing caused by small solid particles 3, PEEK in molten state is spirally coated during the coating process of composite steel pipe 1; the angle between the spiral direction and the axial direction is 45 degrees. The change of coating direction changes the stress direction of PEEK coating film 2. Even if it is subjected to external force 4 such as dust or knocking later, the axial tearing of PEEK coating film 2 is avoided due to the inconsistency of the direction of external force 4 and stress.

[0050] refer to Figure 4 Furthermore, on the basis of the composite steel pipe 1 being covered with a PEEK coating film 2 extruded in a spiral direction, a layer of PFA film is spirally coated again in the opposite direction of the spiral extrusion of the PEEK coating film 2; the double coating in the opposite direction makes the stress more stable; due to the smooth properties of PFA material, some dust will be blocked from the outside, and even if it is subjected to external impact force, the impact force will be greatly reduced when it reaches the PFFE coating film 2 through the buffer of PFA film; thus avoiding tearing of the coating film.

[0051] Example 2:

[0052] Testing experiment:

[0053] Gas permeability experiment:

[0054] Experimental sample 1: PEEK film;

[0055] Sample names: 1#, 2#, 3#;

[0056] Sample thickness: 1#: 0.213mm, 2#: 0.342mm, 3#: 0.285mm;

[0057] Experimental environment: Temperature: 23 degrees Celsius; Test gas: Air;

[0058] Testing equipment: Differential pressure gas permeation instrument, model: G2 / 132; Thin film thickness gauge, model: TG-3130-A3;

[0059] Testing standard: GB / T 1038-2000;

[0060] Test results:

[0061] #1: 24.9cm 3 / m 2 • 24h - 0.1MPa;

[0062] #2: 6.20cm 3 / m 2 • 24h - 0.1MPa;

[0063] #3: 8.78cm 3 / m 2 • 24h - 0.1MPa;

[0064] Experimental sample 2: PFA film;

[0065] Sample names: 1#, 2#, 3#;

[0066] Sample thickness: 1#: 0.213mm, 2#: 0.342mm, 3#: 0.285mm;

[0067] Experimental environment: Temperature: 23 degrees Celsius; Test gas: Air;

[0068] Testing equipment: Differential pressure gas permeation instrument, model: G2 / 132; Thin film thickness gauge, model: TG-3130-A3;

[0069] Testing standard: GB / T 1038-2000;

[0070] Test results:

[0071] #1: 372cm 3 / m 2 • 24h - 0.1MPa;

[0072] #2: 195cm 3 / m 2 • 24h - 0.1MPa;

[0073] #3: 213cm 3 / m 2 • 24h - 0.1MPa;

[0074] Experimental Sample 3: PEEK film and PFA film;

[0075] Sample names: 1#, 2#, 3#;

[0076] Sample thickness:

[0077] #1: 0.426mm, of which the PEEK film thickness is 0.213mm and the PFA film thickness is 0.213mm.

[0078] #2: 0.684mm, of which the PEEK film thickness is 0.342mm and the PFA film thickness is 0.342mm.

[0079] 3#: 0.56mm, of which the PEEK film thickness is 0.285mm and the PFA film thickness is 0.285mm;

[0080] Sample condition: PFA film coated on PEEK film

[0081] Experimental environment: Temperature: 23 degrees Celsius; Test gas: Air;

[0082] Testing equipment: Differential pressure gas permeation instrument, model: G2 / 132; Thin film thickness gauge, model: TG-3130-A3;

[0083] Testing standard: GB / T 1038-2000;

[0084] Test results:

[0085] #1: 4.37cm 3 / m 2 • 24h - 0.1MPa;

[0086] #2: 1.94cm 3 / m 2 • 24h - 0.1MPa;

[0087] #3: 2.86cm 3 / m 2 • 24h - 0.1MPa;

[0088] analyze:

[0089] The above experiments show that under the same experimental conditions, the thicker the PEEK film sample, the lower the gas permeability, and the less oxygen in the air comes into contact with the steel pipe, thus prolonging the time before the steel pipe rusts and increasing its service life. However, considering cost, a thicker PEEK film is not necessarily better. In the above experimental sample 1, from sample #3 to sample #2, the thickness increased by 0.057 mm, and the difference in gas permeability was 2.58 cm. 3 / m 2 • 24h - 0.1MPa; From sample #3 to sample #1, the thickness decreased by 0.072, and the difference in gas permeability was 16.72cm. 3 / m 2 • 24h-0.1MPa; For sample #3, the gas permeability did not decrease significantly with increasing thickness, indicating only a slight improvement in its barrier effect. However, for sample #3, the gas permeability increased significantly with decreasing thickness, indicating a marked decrease in its barrier effect. Therefore, it can be concluded that PEEK material has a relatively cost-effective thickness range. A PEEK film thickness of around 0.213-0.285mm can meet the barrier requirements.

[0090] Compared with the PFA film in experimental sample 2, under the same experimental conditions, the gas permeability of the PFA film is significantly weaker than that of the PEEK film, showing a large data difference; its barrier effect is reduced; the barrier effect of the 0.213mm thick PEEK film is still much greater than that of the 0.342mm thick PFA film; the barrier effect of the PEEK film is better than that of the PFA film.

[0091] For experimental sample 3, if a double-layer film, namely PEEK film and PFA film, is used on the steel pipe, with the PEEK film covering the steel pipe and the PFA film covering the PEEK film, its barrier effect will be more prominent.

[0092] Example 3:

[0093] Thermal conductivity experiment:

[0094] Experimental sample 1: PEEK film;

[0095] Experimental environment: Temperature (25±5) degrees Celsius; Humidity (30-70)%RH;

[0096] Testing equipment: LFA467 laser thermal conductivity meter;

[0097] Testing standard: ASTM E 1461-2013;

[0098] Test results:

[0099] 0.270W / (m*K);

[0100] Experimental sample 2: PFA film;

[0101] Experimental environment: Temperature (25±5) degrees Celsius; Humidity (30-70)%RH;

[0102] Testing equipment: LFA467 laser thermal conductivity meter;

[0103] Testing standard: ASTM E 1461-2013;

[0104] Test results:

[0105] 0.209W / (m*K);

[0106] Experimental Sample 3: PEEK film, PFA film;

[0107] Sample condition: PFA film coated on PEEK film

[0108] Experimental environment: Temperature (25±5) degrees Celsius; Humidity (30-70)%RH;

[0109] Testing equipment: LFA467 laser thermal conductivity meter;

[0110] Testing standard: ASTM E 1461-2013;

[0111] Test results:

[0112] 0.258W / (m*K);

[0113] Analysis: Thermal conductivity experiments show that PEEK film has excellent thermal conductivity; this good thermal conductivity allows steel pipes to adapt to more complex and harsh environments; however, in environments with large temperature differences, rapid temperature changes are likely to occur. PFA film has weaker thermal conductivity than PEEK film, which can slow down the rate of temperature rise and fall. If PFA film and PEEK film are stacked together, the thermal conductivity is satisfied, while also avoiding rapid temperature changes that could damage the steel pipe and extend its service life.

[0114] Example 4:

[0115] 3. Water vapor transmission rate experiment:

[0116] Experimental sample 1: PEEK film;

[0117] Sample names: 1#, 2#, 3#;

[0118] Sample thickness: 1#: 0.213mm, 2#: 0.342mm, 3#: 0.285mm;

[0119] Experimental environment: Water vapor permeability area: 33.183 cm²2 Cavity environment: 38 degrees Celsius, 90% RH;

[0120] Testing equipment: Water vapor transmission rate testing system, model: W3 / 062; Thin film thickness gauge, model: TG-3130-A3;

[0121] Testing standard: GB1037-2021;

[0122] Test results:

[0123] 3.4g / m 2 ·24h;

[0124] 1.63g / m 2 ·24h;

[0125] 2.56g / m 2 ·24h;

[0126] Experimental sample 2: PFA film;

[0127] Sample names: 1#, 2#, 3#;

[0128] Sample thickness: 1#: 0.213mm, 2#: 0.342mm, 3#: 0.285mm;

[0129] Experimental environment: Water vapor permeability area: 33.183 cm² 2 Cavity environment: 38 degrees Celsius, 90% RH;

[0130] Testing equipment: Water vapor transmission rate testing system, model: W3 / 062; Thin film thickness gauge, model: TG-3130-A3;

[0131] Testing standard: GB1037-2021;

[0132] Test results:

[0133] 0.285g / m 2 ·24h;

[0134] 0.597g / m 2 ·24h;

[0135] 0.466g / m 2 ·24h;

[0136] Experimental Sample 3: PEEK film and PFA film;

[0137] Sample names: 1#, 2#, 3#;

[0138] 1#: 0.426mm, of which the PEEK film thickness is 0.213mm and the PFA film thickness is 0.213mm;

[0139] #2: 0.684mm, of which the PEEK film thickness is 0.342mm and the PFA film thickness is 0.342mm;

[0140] 3#: 0.56mm, of which the PEEK film thickness is 0.285mm and the PFA film thickness is 0.285mm;

[0141] Sample condition: PFA film coated on PEEK film

[0142] Experimental environment: Water vapor permeability area: 33.183 cm² 2 Cavity environment: 38 degrees Celsius, 90% RH;

[0143] Testing equipment: Water vapor transmission rate testing system, model: W3 / 062; Thin film thickness gauge, model: TG-3130-A3;

[0144] Testing standard: GB1037-2021;

[0145] Test results:

[0146] 1.64g / m 2 ·24h;

[0147] 1.01g / m 2 ·24h;

[0148] 1.31g / m 2 ·24h;

[0149] The water vapor transmission rate experiment shows that the water vapor transmission rate of PEEK film increases with the increase of PEEK film thickness, thus increasing the blocking effect. This ensures that the inside of the steel pipe is in a dry environment, meeting the water vapor blocking effect during normal use. It also prevents water vapor from sublimating and corroding the steel pipe due to rapid temperature changes. The water vapor transmission rate experiment of PFA film shows that the water vapor blocking effect of PFA film is better than that of PEEK film. When PEEK film and PFA film are stacked together, the water vapor blocking effect is better than that of PEEK film alone.

[0150] In summary, the three experiments demonstrate that PEEK film is a high-performance barrier material that maintains high performance even at a relatively thin thickness. It exhibits outstanding gas barrier properties, and its excellent thermal conductivity ensures the stability of the steel pipe's interior, preventing chemical reactions within the pipe. Its thinness also ensures economic efficiency. When combined with PFA film, with the PFA film covering the outer wall of the PEEK film, the overall barrier performance is further enhanced. The smoothness of the PFA film helps to block dust and other contaminants. The double-layer coating of PFA and PEEK films further strengthens the barrier effect against water vapor, thereby extending the service life of the steel pipe and indirectly reducing maintenance costs.

[0151] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for manufacturing a high-barrier steel-plastic composite pipe based on PEEK material, characterized in that: Includes the following steps: S1. Degreasing steel pipes: removing oil and impurities from the surface of steel pipes by heating. S2. High-temperature drying of PEEK raw material yields product A; S3. The A product is extruded into the first mold through a high-pressure extruder, so that the A product is continuously extruded on the outer surface of the steel pipe that is moving axially at a uniform speed in a molten state. The A product and the steel pipe are continuously extruded as a whole. While the steel pipe is being extruded on the steel pipe that is moving axially at a uniform speed, the steel pipe is rotated, so that the A product and the steel pipe are spirally coated; thus, a steel-plastic composite pipe coated with the A product is obtained. S4. After water cooling, the steel-plastic composite pipe coated with product A is heated to relieve stress; at the same time, recrystallization is completed to obtain the finished product; After step S4, there are also steps S5 and S6; S5. The PFA raw material is dried at high temperature to obtain product B, which is then extruded into the second mold through a high-pressure extruder. The molten product B is continuously spirally extruded onto the steel-plastic composite pipe covered by product A which is moving axially at a uniform speed, to obtain a steel-plastic composite pipe with double-layer AB coating. S6. After water cooling, the steel-plastic composite pipe with double AB coating is heated to remove stress; at the same time, recrystallization is completed to obtain the finished product; Product B is continuously spirally extruded, with the rotation direction opposite to that in step S3; Product A is coated on the outer surface of the steel pipe, and Product B is coated on the outer surface of Product A; there is no gap between Product A and Product B.

2. The method for manufacturing a high-barrier steel-plastic composite pipe based on PEEK material according to claim 1, characterized in that: In step S1, the steel pipe is heated to a temperature of 140-160 degrees Celsius for 1-2 minutes.

3. The method for manufacturing a high-barrier steel-plastic composite pipe based on PEEK material according to claim 1, characterized in that: In step S4, water cooling and reheating are used to relieve stress and recrystallize simultaneously, with the reheating temperature at 200-250 degrees Celsius. In step S6, water cooling and reheating are used to relieve stress and recrystallize simultaneously, with the reheating temperature at 200-250 degrees Celsius. In steps S4 and S6, water cooling and reheating are used to relieve stress and recrystallize simultaneously, and the fixture is heated together.

4. The method for manufacturing a high-barrier steel-plastic composite pipe based on PEEK material according to claim 1, characterized in that: The thickness of the PEEK film and PFA film coated on the outer surface of the steel pipe is different. The thickness of the PEEK film is 0.2mm-0.25mm, and the thickness of the PFA film is 0.25mm-0.3mm.

5. The method for manufacturing a high-barrier steel-plastic composite pipe based on PEEK material according to claim 1, characterized in that: The drying temperature for PEEK raw materials is 150-160 degrees Celsius, and the drying time is 2-3 hours.

6. The method for manufacturing a high-barrier steel-plastic composite pipe based on PEEK material according to claim 1, characterized in that: In step S3, the high-pressure extruder applies an extrusion pressure between 70-140 MPa to product A, and the melting temperature of product A is maintained at 370-390 degrees Celsius. The molten product A is extruded into the first mold; the axial movement speed of the product A is 0.7 m / min.

7. The method for manufacturing a high-barrier steel-plastic composite pipe based on PEEK material according to claim 1, characterized in that: In step S5, the high-pressure extruder applies a pressure of 20 MPa to product B and maintains the molten temperature of product B at 360-380 degrees Celsius. The molten product B is extruded into the second mold, and the axial movement speed of product B is 0.7 m / min.

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