A special ultra-high molecular weight polyethylene material for coating sucker rods that is crack-resistant, wear-resistant, and easy to process and its preparation method

Abstract

The invention discloses a special ultra-high molecular weight polyethylene material for coating sucker rods, which is crack-resistant, wear-resistant, and easy to process, and a preparation method thereof. The special material comprises: 50 wt%-78 wt% of ultra-high molecular weight polyethylene, 20 wt%-47 wt% of polyethylene silane grafted material, 0.6 wt%-2 wt% of end-capped hydroxy silicone oil, and 1 wt% of an antioxidant. The preparation method of the special material comprises: first, mixing the polyethylene silane grafted material and the end-capped monohydroxy silicone oil in a twin-screw extruder to form pellets, and then mixing the pelletized material with the ultra-high molecular weight polyethylene and the antioxidant in a twin-screw pelletizer to form pellets. The advantages of the present invention are that the sucker rod coating can be prevented from cracking in a harsh environment of high temperature and the presence of water and oil, and the special material has good processing performance, is less likely to produce pre-crosslinked particles during production, has good wear resistance, and has good application prospects.

Description

Technical Field

[0001] The invention relates to the field of oilfield mining equipment, and in particular to a special ultra-high molecular weight polyethylene material for coating a pumping rod that is crack-resistant, wear-resistant and easy to process, and a preparation method thereof. Background Art

[0002] The sucker rod is a slender rod connected to a polished rod at the top and a well pump at the bottom. The sucker rod transmits power from surface equipment to the downhole well pump. The up-and-down motion of the sucker rod drives the pump's piston, pumping the oil reservoir fluid to the surface. During operation, the sucker rod is exposed to high temperatures, water, saline-alkali, and corrosive media such as carbon dioxide, hydrogen sulfide, and bacteria. This harsh working environment exacerbates corrosion problems in the sucker rod, significantly shortening its service life.

[0003] To extend the life of sucker rods, several methods are commonly used. One is surface coating with metal alloys, such as the corrosion-resistant and wear-resistant TiCN composite coating and its spraying method, and the corrosion-resistant and wear-resistant pumping unit polished rod (CN107245688B). Another approach is coating with polymer materials or their glass or carbon fiber composites, such as polyethylene (CN205172453U), a new polyethylene fully coated sucker rod; nylon (CN105968795A), a modified nylon coating anti-corrosion formula and process for sucker rod heads; polyimide (CN112227965A), a high-temperature resistant coated sucker rod; and polyketone (CN111205624B), an aliphatic polyketone fully coated sucker rod and its preparation method.

[0004] Fiber composite materials, CN109488219B, multi-layered corrosion-resistant and high-temperature resistant composite continuous pumping rod and its preparation process; among these, ultra-high molecular weight polyethylene (UHMWPE) modified coating materials are relatively mature, offer excellent overall performance, and are widely used. However, if the formulation is not optimal, the UHMWPE coating can develop surface cracking over long-term use. This is due to the significant difference in shrinkage between the metal rod and the UHMWPE. After the UHMW coating is applied to the metal pumping rod, the coating is subjected to long-term stress, which can lead to stress cracking in harsh environments such as high temperatures and the presence of oil and water.

[0005] From a microscopic perspective, the mechanism is that the lacing molecules between the ultra-high molecular weight polyethylene (UHMWPE) lamellae are relatively few. Under high temperature and oil-water conditions, and under stress, the lacing molecules between the lamellae disentangle or break. Macroscopically, this manifests as small cracks forming on the coating surface over time. These cracks grow rapidly, leading to coating failure and pumper rod failure. Summary of the Invention

[0006] Ultra-high molecular weight polyethylene (UHMWPE) has a high molecular weight and high viscosity, making it difficult to process. It typically requires mixing with general-purpose polyethylene and additives before processing. However, this reduces its wear resistance. Generally, its maximum processing temperature is above 250°C.

[0007] Polyethylene silane grafted materials have silane grafted onto the polyethylene molecular chains. After being processed into finished products, the silane cross-links under the action of high temperature and water, connecting the molecular chains between the polyethylene platelets with silicon-oxygen bonds. This significantly improves the polyethylene's crack resistance, high-temperature strength, and wear resistance. However, silane-grafted polyethylene is sensitive to high temperatures during processing, and the maximum processing temperature generally does not exceed 220°C. Exceeding this temperature or prolonged exposure to high temperatures can easily lead to the formation of pre-crosslinked particles, resulting in improper molding, rough surfaces, and poor performance.

[0008] The present invention aims to overcome the shortcomings of the prior art and provides a special ultra-high molecular weight polyethylene material for coating sucker rods that is crack-resistant, wear-resistant, and easy to process, and a preparation method thereof. The special material comprises: 50 wt%-78 wt% of ultra-high molecular weight polyethylene, 20 wt%-47 wt% of polyethylene silane grafted material, 0.6 wt%-2 wt% of end-capped hydroxy silicone oil, and 1 wt% of antioxidant. The special material is prepared by first mixing the polyethylene silane grafted material and the end-capped monohydroxy silicone oil in a twin-screw extruder to form pellets, and then mixing the pelletized material with ultra-high molecular weight polyethylene and an antioxidant in a twin-screw pelletizer to form pellets. The present invention has the advantages of preventing the sucker rod coating from cracking in harsh environments such as high temperature and the presence of water and oil, and has good processing performance, is less likely to produce pre-crosslinked particles during production, has good wear resistance, and has good application prospects.

[0009] The present invention first melts the polyethylene silane grafted material and the single-end hydroxy silicone oil in a twin-screw granulator and melt-blends them. The reaction between the two causes the reactive groups of the polyethylene silane grafted material to become passivated, and at high temperatures, the rate of the cross-linking reaction is greatly reduced. The single-end hydroxy silicone oil can also act as a lubricant, reducing friction loss. Then, by melt-blending it with ultra-high molecular weight polyethylene at high temperatures, a special ultra-high molecular weight polyethylene material for coating pump rods that is crack-resistant, wear-resistant, and easy to process can be obtained. The material thus obtained combines the advantages of ultra-high molecular weight polyethylene and polyethylene silane grafted material. During use, under the action of water and high temperature, the silane cross-linked polyethylene grafted material cross-links with each other, having very good wear resistance and crack resistance, while also maintaining good processing performance.

[0010] In order to achieve the above technical effects, the following technical solutions are adopted:

[0011] A special ultra-high molecular weight polyethylene material for coating sucker rods that is crack-resistant, wear-resistant, and easy to process, comprising the following components:

[0012] Ultra-high molecular weight polyethylene 50-78%; polyethylene silane grafted material 20%-47%; end-capped monohydroxy silicone oil 0.6%-2%; antioxidant 1%;

[0013] The mass ratio of the end-capped monohydroxy silicone oil to the polyvinyl silane grafted material is not less than 0.03, mainly because all cross-linking groups have enough silicone oil to react with.

[0014] Furthermore, the molecular weight of the ultra-high molecular weight polyethylene is 1 million to 7 million; the density is 0.930 g / cm 3 -0.945 g / cm 3 .

[0015] Furthermore, the ultra-high molecular weight polyethylene is a mixture of one or two or more ultra-high molecular weight polyethylenes with different molecular weights.

[0016] Furthermore, the crosslinking degree of the polyethylene silane grafted material is 70%-90%; the density is 0.938 g / cm 3 -0.960g / cm 3 .

[0017] Furthermore, the molecular weight of the end-capped monohydroxy silicone oil is 1,000-30,000.

[0018] Furthermore, the structural formula of the end-capped monohydroxy silicone oil is:

[0019] .

[0020] Furthermore, the antioxidant is a general antioxidant for polyethylene.

[0021] Furthermore, the antioxidant is one or more of 1010 and 168.

[0022] Furthermore, the preparation method is:

[0023] First, the polyethylene silane grafted material and the blocked monohydroxy silicone oil are mixed and granulated in a twin-screw extruder, and then the granulated material is mixed with ultra-high molecular weight polyethylene and an antioxidant and granulated in a twin-screw granulator to obtain the anti-cracking, wear-resistant and easy-to-process ultra-high molecular weight polyethylene special material for coating the sucker rod.

[0024] Furthermore, the specific method of mixing the polyethylene silane grafted material and the blocked monohydroxy silicone oil in a twin-screw extruder to form granules is as follows:

[0025] The polyethylene silane grafted material and the end-capped hydroxy silicone oil are mixed and granulated in a twin-screw extruder at a processing temperature of 160-210°C. The twin-screw extruder has nine zones, and the temperature settings of each zone are as follows: zone one 160°C, zone two 160-180°C, zone three 170-190°C, zone four 170-190°C, zone five 170-190°C, zone six 180-200°C, zone seven 180-210°C, zone eight 180-210°C, zone nine 180-210°C, and the die head 180-210°C. The screw speed during the melt extrusion process is 250-400 rpm. The end-capped monohydroxy silicone oil can passivate the reactive groups of the silane grafted polyethylene and prevent the occurrence of cross-linking reaction at high temperature.

[0026] The specific method of mixing the granulated material with ultra-high molecular weight polyethylene and antioxidant and then granulating in a twin-screw granulator is as follows:

[0027] Pelletization is performed in a twin-screw extruder, with the following zone temperatures set: Zone 1 190-200°C, Zone 2 190-210°C, Zone 3 190-210°C, Zone 4 200-220°C, Zone 5 200-220°C, Zone 6 220-240°C, Zone 7 240-260°C, Zone 8 250-270°C, Zone 9 260-280°C, and the die head 260-280°C. Extrusion is performed at 190-280°C for the sucker rod coating. Pre-crosslinking is less likely to occur during processing. During use, the silane-grafted polyethylene crosslinks in a high-temperature, water-based environment, significantly improving the coating's wear resistance and crack resistance.

[0028] The beneficial effects of the present invention are:

[0029] The present invention provides a special ultra-high molecular weight polyethylene material for coating sucker rods that is crack-resistant, wear-resistant, and easy to process, and a preparation method thereof. The special material comprises: 50 wt%-78 wt% of ultra-high molecular weight polyethylene, 20 wt%-47 wt% of polyethylene silane grafted material, 0.6 wt%-2 wt% of end-capped hydroxy silicone oil, and 1 wt% of antioxidant. The preparation method comprises: first, mixing the polyethylene silane grafted material and the end-capped monohydroxy silicone oil in a twin-screw extruder to form pellets, and then mixing the pelletized material with the ultra-high molecular weight polyethylene and the antioxidant in a twin-screw pelletizer to form pellets. The advantages of the present invention are that it can prevent the sucker rod coating from cracking in harsh environments such as high temperature and the presence of water and oil, and has good processing performance. Pre-crosslinked particles are less likely to occur during production, and the material has good wear resistance, thereby having good application prospects.

[0030] The present invention first melts the polyethylene silane grafted material and the single-end hydroxy silicone oil in a twin-screw granulator and melt-blends them. The reaction between the two causes the reactive groups of the polyethylene silane grafted material to become passivated, and at high temperatures, the rate of the cross-linking reaction is greatly reduced. The single-end hydroxy silicone oil can also act as a lubricant, reducing friction loss. Then, by melt-blending it with ultra-high molecular weight polyethylene at high temperatures, a special ultra-high molecular weight polyethylene material for coating pump rods that is crack-resistant, wear-resistant, and easy to process can be obtained. The material thus obtained combines the advantages of ultra-high molecular weight polyethylene and polyethylene silane grafted material. During use, under the action of water and high temperature, the silane cross-linked polyethylene grafted material cross-links with each other, having very good wear resistance and crack resistance, while also maintaining good processing performance. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0032] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0033] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations and / or combinations thereof.

[0034] Example 1:

[0035] Taking the total mass fraction as 100%, the mass fraction of each component is as follows:

[0036] Ultra-high molecular weight polyethylene, molecular weight 3 million, accounting for 68 wt% of the total mass ratio; polyethylene silane grafted material, maximum cross-linking degree 80%, accounting for 30 wt% of the total mass ratio; end-capped monohydroxy silicone oil, molecular weight 1000, accounting for 1 wt% of the total mass ratio; antioxidant is a mixture of 1010 and 168 in a mass ratio of 1:1; the antioxidant accounts for 1 wt% of the total mass ratio.

[0037] The preparation process is divided into two steps. In the first step, the polyethylene silane grafted material and the end-capped monohydroxy silicone oil are added to a twin-screw extruder for melt blending and granulation. The processing temperature is between 160 and 210 degrees. The twin-screw extruder has a total of nine zones, and the temperature settings of each zone are as follows: Zone 1 160°C, Zone 2 160-180°C, Zone 3 170-190°C, Zone 4 170-190°C, Zone 5 170-190°C, Zone 6 180-200°C, Zone 7 180-210°C, Zone 8 180-210°C, Zone 9 180-210°C, and the die head 180-210°C; the twin-screw speed during the melt extrusion process is 250-400rpm.

[0038] In the second step, the prepared material is melt-blended with ultra-high molecular weight polyethylene and an antioxidant in a twin-screw extruder to form pellets. The temperature settings for each zone are as follows: Zone 1 190-200°C, Zone 2 190-210°C, Zone 3 190-210°C, Zone 4 200-220°C, Zone 5 200-220°C, Zone 6 220-240°C, Zone 7 240-260°C, Zone 8 250-270°C, Zone 9 260-280°C, and the die head 260-280°C. The twin-screw speed during the melt extrusion process is 250-400 rpm. Extrusion is performed normally at 190-280°C to coat the sucker rod.

[0039] The other examples are compared with Example 1, except that the proportions of the components are different, and the preparation methods are the same. The proportions of the components are summarized in Table 1:

[0040] Table 1 Mass fraction of components in each embodiment

[0041]

[0042] For Comparative Examples 1 and 2, after the raw materials and antioxidant were blended, they were directly pressed on a molding machine to prepare test samples for testing. For Comparative Examples 3 to 7, the only difference between the components and the preparation method was the same as in Example 1. The component ratios are summarized in Table 2:

[0043] Table 2 Mass fraction of components in each comparative example

[0044]

[0045] The above embodiments and comparative examples were subjected to performance tests:

[0046] For stress cracking resistance and quality wear performance test samples, test specimens are prepared by compression molding according to the relevant standards, and then treated in 95℃ water for 48 hours to carry out cross-linking reaction. The samples are then taken out and subjected to stress cracking resistance and sliding friction wear tests according to the relevant test standards.

[0047] Stress cracking resistance: Prepare test samples and test stress resistance according to GB / T1842 Plastic Polyethylene Environmental Stress Cracking Test Method;

[0048] Quality wear performance: Prepare test samples and conduct performance tests according to the provisions of GB / T3960 Plastics Sliding Friction and Wear Test Method;

[0049] Extrusion processing performance: the pelletized sucker rod is coated with anti-cracking, easy-to-process ultra-high molecular weight polyethylene special material and added into the ⌀63 extruder. The 6 zone temperatures are set at 200℃, 220℃, 240℃, 260℃, 280℃, 280℃, the die head temperature is 280℃, the extruder screw speed is 40rpm, and the extrusion condition is observed, as well as the appearance of the extruded material strips.

[0050] The performance test results in the embodiment are listed in Table 3:

[0051] Table 3 Performance results of various embodiments

[0052]

[0053] The performance test results in the comparative example are listed in Table 4:

[0054] Table 4 Performance results of each comparative example

[0055]

[0056] It can be seen from Examples 1, 2, and 3 that as the amount of polyethylene silane grafted material increases, the environmental stress cracking resistance increases and the quality wear decreases. However, the processing performance is relatively good. Compared with Examples 1, 4, and 5, the greater the maximum crosslinking degree of the polyethylene silane grafted material, the greater the environmental stress cracking resistance and the quality wear decreases. Compared with Examples 1, 6, and 7, the greater the molecular weight of the ultra-high molecular weight polyethylene, the greater the environmental stress cracking resistance and the quality wear decreases. However, the surface of the extruded material strips will become more and more matte, but the extrusion volume is relatively stable. Compared with Examples 1, 8, and 9, the amount of silicone oil is different, the environmental stress cracking resistance remains unchanged, and the quality wear decreases. It should be that there is more silicone oil, which increases lubrication.

[0057] Comparing Example 1 with Comparative Examples 1 and 2, Example 1 and Comparative Examples 2 demonstrate the normal performance of ultra-high molecular weight polyethylene and polyethylene silane grafted materials. Example 1 exhibits significantly better stress cracking resistance than ultra-high molecular weight polyethylene. Cross-linked polyethylene, due to the chemical bonding of molecular chains, exhibits the best cracking resistance. Example 1 exhibits superior wear resistance compared to ultra-high molecular weight polyethylene and polyethylene silane grafted materials due to the presence of a single-terminated hydroxyl silicone oil lubricant. However, the processing properties of Comparative Examples 1 and 2 are both poor. The ultra-high molecular weight polyethylene is not plasticized, and the silane cross-linked polyethylene exhibits numerous large and small cross-linked particles during extrusion. Comparative Example 3, compared to Comparative Example 1, incorporates a single-terminated hydroxyl silicone oil and undergoes two additional twin-screw extrusion processes. Comparing Example 3 with Example 1, all properties of Comparative Example 3 were significantly inferior to those of Example 1. Comparative Example 2 showed little difference in all properties except for a modest improvement in wear resistance. The single-end-capped hydroxy silicone oil also improved wear resistance. Comparative Example 4, compared with Example 2, included additional silicone oil and two additional twin-screw extrusion processes. All properties of Comparative Example 4 were significantly inferior to those of Example 1. This was due to the high-temperature extrusion process, which produced numerous large and small cross-linked particles. These particles caused stress concentration, resulting in poor performance. Comparing Example 4 with Example 2, Comparative Example 2 lacked the high-temperature extrusion process and lacked pre-cross-linked particles, leading to stress concentration. Therefore, the properties of Comparative Example 2 were inherent to the material and outperformed Comparative Example 4. Comparing Example 1 with Comparative Example 5, Example 1 used ultra-high molecular weight polyethylene as the continuous phase, while Comparative Example 5 used silane-grafted polyethylene. Due to cross-linking during processing, the silane-grafted polyethylene contained excessive pre-cross-linked particles. During the wear process, some particles were detached, resulting in a roughened wear surface, poor wear performance, and significantly increased mass loss. Processing performance is also poor. Due to stress concentration caused by the pre-crosslinked particles, crack resistance is also poor. Comparing Example 1 with Comparative Example 6 and Comparative Example 7, Comparative Example 7 does not contain a single-end-capped hydroxyl silicone oil lubricant, while Comparative Example 6 does not contain enough single-end-capped hydroxyl silicone oil lubricant. Due to the presence of pre-crosslinked particles, the environmental crack resistance, wear resistance, and processing performance of Example 1 are all better than those of Comparative Example 6, and Comparative Example 6 is better than Comparative Example 7.

[0058] In summary, the present invention discloses a special ultra-high molecular weight polyethylene material for coating sucker rods that is crack-resistant, wear-resistant, and easy to process, and a preparation method thereof; the special material comprises: 50 wt%-78 wt% of ultra-high molecular weight polyethylene, 20 wt%-47 wt% of polyethylene silane grafted material, 0.6 wt%-2 wt% of end-capped hydroxy silicone oil, and 1 wt% of antioxidant; the preparation method of the special material comprises: first, mixing the polyethylene silane grafted material and the end-capped monohydroxy silicone oil in a twin-screw extruder to form pellets, and then mixing the pelletized material with ultra-high molecular weight polyethylene and an antioxidant in a twin-screw pelletizer to form pellets; the advantages of the present invention are that it can prevent the sucker rod coating from cracking in harsh environments of high temperature and water and oil, and has good processing performance, is less likely to produce pre-crosslinked particles during production, has good wear resistance, and has good application prospects.

[0059] The present invention first melts the polyethylene silane grafted material and the single-end hydroxy silicone oil in a twin-screw granulator and melt-blends them. The reaction between the two causes the reactive groups of the polyethylene silane grafted material to become passivated, and at high temperatures, the rate of the cross-linking reaction is greatly reduced. The single-end hydroxy silicone oil can also act as a lubricant, reducing friction loss. Then, by melt-blending it with ultra-high molecular weight polyethylene at high temperatures, a special ultra-high molecular weight polyethylene material for coating pump rods that is crack-resistant, wear-resistant, and easy to process can be obtained. The material thus obtained combines the advantages of ultra-high molecular weight polyethylene and polyethylene silane grafted material. During use, under the action of water and high temperature, the silane cross-linked polyethylene grafted material cross-links with each other, having very good wear resistance and crack resistance, while also maintaining good processing performance.

[0060] At this point, those skilled in the art will recognize that, although the embodiments of the present invention have been shown and described in detail herein, many other variations or modifications consistent with the principles of the present invention may be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and deemed to cover all such other variations or modifications.

Claims

1. A special ultra-high molecular weight polyethylene material for coating sucker rods that is crack-resistant, wear-resistant, and easy to process, characterized in that: The special material is the following components: Ultra-high molecular weight polyethylene 50-78%; polyethylene silane grafted material 20%-47%; end-capped monohydroxy silicone oil 0.6%-2%; antioxidant 1%; The mass ratio of the end-capped monohydroxy silicone oil to the polyvinyl silane grafted material is not less than 0.

03.

2. The anti-cracking, wear-resistant and easy-to-process ultra-high molecular weight polyethylene special material for coating sucker rods as claimed in claim 1, characterized in that: The molecular weight of the ultra-high molecular weight polyethylene is 1 million to 7 million; the density is 0.930 g / cm 3 -0.945 g / cm 3 .

3. The anti-cracking, wear-resistant and easy-to-process ultra-high molecular weight polyethylene special material for coating sucker rods as claimed in claim 1, characterized in that: The ultra-high molecular weight polyethylene is a mixture of one or two or more ultra-high molecular weight polyethylenes with different molecular weights.

4. The anti-cracking, wear-resistant and easy-to-process ultra-high molecular weight polyethylene special material for coating sucker rods as claimed in claim 1, characterized in that: The crosslinking degree of the polyethylene silane grafted material is 70%-90%; the density is 0.938 g / cm 3 -0.960g / cm 3 .

5. The anti-cracking, wear-resistant and easy-to-process ultra-high molecular weight polyethylene special material for coating sucker rods as claimed in claim 1, characterized in that: The molecular weight of the end-capped monohydroxy silicone oil is 1000-30000.

6. The anti-cracking, wear-resistant and easy-to-process ultra-high molecular weight polyethylene special material for coating sucker rods as claimed in claim 1, characterized in that: The structural formula of the end-capped monohydroxy silicone oil is: 。 7. The anti-cracking, wear-resistant and easy-to-process ultra-high molecular weight polyethylene special material for coating sucker rods as claimed in claim 1, characterized in that: The antioxidant is a general antioxidant for polyethylene.

8. The anti-cracking, wear-resistant and easy-to-process ultra-high molecular weight polyethylene special material for coating sucker rods as claimed in claim 7, characterized in that: The antioxidant is one or more of 1010 and 168.

9. The method for preparing a special ultra-high molecular weight polyethylene material for coating a sucker rod that is crack-resistant, wear-resistant, and easy to process as claimed in claim 1, characterized in that: The preparation method is: First, the polyethylene silane grafted material and the blocked monohydroxy silicone oil are mixed and granulated in a twin-screw extruder, and then the granulated material is mixed with ultra-high molecular weight polyethylene and an antioxidant and granulated in a twin-screw granulator to obtain the anti-cracking, wear-resistant and easy-to-process ultra-high molecular weight polyethylene special material for coating the sucker rod.

10. The method for preparing a special ultra-high molecular weight polyethylene material for coating a sucker rod that is crack-resistant, wear-resistant, and easy to process as claimed in claim 9, characterized in that: The specific method of mixing the polyethylene silane grafted material and the blocked monohydroxy silicone oil in a twin-screw extruder to form granules is as follows: The polyethylene silane grafted material and the end-capped monohydroxy silicone oil are mixed and granulated in a twin-screw extruder at a processing temperature of 160-210°C. The twin-screw extruder has nine zones, and the temperature settings of each zone are as follows: zone 1 160°C, zone 2 160-180°C, zone 3 170-190°C, zone 4 170-190°C, zone 5 170-190°C, zone 6 180-200°C, zone 7 180-210°C, zone 8 180-210°C, zone 9 180-210°C, and die head 180-210°C; the screw speed during the melt extrusion process is 250-400 rpm; The specific method of mixing the granulated material with ultra-high molecular weight polyethylene and antioxidant and then granulating in a twin-screw granulator is as follows: Granulation was carried out in a twin-screw extruder, with the temperature settings of each zone being: 190-200°C in zone one, 190-210°C in zone two, 190-210°C in zone three, 200-220°C in zone four, 200-220°C in zone five, 220-240°C in zone six, 240-260°C in zone seven, 250-270°C in zone eight, 260-280°C in zone nine, and 260-280°C in the die head; extrusion was carried out normally at 190-280°C to coat the sucker rod.

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