Method for preparing HDPE (high-density polyethylene) composite anti-fouling pipe through toughening modification of SA-g-Tris

Abstract

The invention discloses a method for preparing a high-density polyethylene composite anti-fouling pipe through SA-g-Tris toughening modification, and belongs to the field of polymer composite material processing. The preparation method comprises the following steps: taking high-density polyethylene, an ethylene-vinyl alcohol copolymer, an EVA-g-MAH compatilizer and an SA-g-Tris hydrophilic agent as raw materials, and carrying out melt mixing, crushing, drying and injection molding to prepare the SA-g-Tris toughened and modified HDPE hydrophilic anti-fouling pipe. The preparation process is simple, the cost is low, and the obtained high-density polyethylene composite anti-fouling pipe has the characteristics of excellent anti-fouling performance, good toughness and the like, can be widely applied to the field of domestic and industrial water conveying pipelines, and has remarkable economic value and social benefit.

Description

Technical Field

[0001] The present invention belongs to the field of polymer composite material processing, and particularly relates to a method for toughening and modifying SA-g-Tris to prepare a high-density polyethylene composite anti-fouling pipe. Background Art

[0002] High-density polyethylene is a thermoplastic resin with high crystallinity and non-polarity. It has good heat resistance and cold resistance, good chemical stability, and good mechanical strength. It is widely used in material fields such as films, pipes, various hollow products, injection-molded products, and fibers. However, when using high-density polyethylene as a pipe, it is required to have stronger hydrophilic properties under specific working conditions to meet the needs of anti-fouling and self-cleaning. Due to the fact that high-density polyethylene is too non-polar and has poor compatibility with polar fillers, simply adding hydrophilic groups to polyethylene pipes cannot achieve a good hydrophilic effect, which greatly limits its wide application in life and production.

[0003] Common hydrophilizing agents on the market usually contain polar groups such as hydroxyl, amino, or carboxyl groups. Representative examples include Span 80 or Tween 80, etc. Although these hydrophilizing agents contain functional groups that can resist fouling and be hydrophilic, they will decompose or become inactivated at temperatures above 150°C. Therefore, at present, the hydrophilic and anti-fouling modification of polyethylene materials is mostly seen in the modification of films at room temperature or the modification of pipes using coatings. This processing method greatly complicates the processing technology and increases the cost.

[0004] At the same time, in order to further make polyethylene pipes more widely used in life and production, while improving the anti-fouling and self-cleaning performance of polyethylene pipes, it is required that the hydrophilizing agent can have good enough compatibility with the matrix and stability under high-temperature conditions to avoid a decline in the mechanical properties of the material. Summary of the Invention

[0005] The pipes obtained by injection molding of pure high-density polyethylene have problems of poor toughness and no hydrophilic and anti-fouling ability. To solve this problem, the present invention provides a method for toughening and modifying SA-g-Tris to prepare a high-density polyethylene composite anti-fouling pipe. It adds the synthesis product of stearic acid and tris(hydroxymethyl)aminomethane as a hydrophilizing agent to the plastic, thereby enhancing the hydrophilic and anti-fouling ability of the polyethylene pipe while also improving the toughness of the plastic pipe. Moreover, the addition of non-polar stearic acid groups also improves the compatibility with the polyethylene matrix. At the same time, the synergistic use of ethylene-vinyl alcohol copolymer can ensure that the strength does not drop significantly while enhancing the hydrophilic performance of the material, so it can have good mechanical properties.

[0006] To achieve the above object, the present invention adopts the following technical solutions: A SA-g-Tris toughened and modified HDPE composite anti-pollution pipe, which is made from high-density polyethylene, ethylene-vinyl alcohol copolymer, EVA-g-MAH compatibilizer, and SA-g-Tris hydrophile through melt mixing, crushing, drying, and injection molding.

[0007] Further, each raw material is in parts by weight: 100 parts by weight of high-density polyethylene, 3 - 5 parts by weight of ethylene-vinyl alcohol copolymer, 1.5 - 2.5 parts by weight of EVA-g-MAH compatibilizer, and 2 - 4 parts by weight of SA-g-Tris hydrophile.

[0008] Further, the high-density polyethylene has a model number of 5000S and a density of 0.941 - 0.960 g / cm³.

[0009] Further, the ethylene-vinyl alcohol copolymer has a model number of EW-3801.

[0010] Further, the EVA-g-MAH compatibilizer has a model number of Bynel 39E660.

[0011] Further, the preparation method of the SA-g-Tris hydrophile includes the following steps: (1) Accurately weigh 1 g of stearic acid, add it to 20 ml of an ethanol solution with a volume concentration of 99%, stir until completely dissolved under the water bath conditions of 40°C and 600 r / min, then slowly add 0.3 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide to the solution, after reacting for 5 min, slowly add 0.3 g of N-hydroxysuccinimide to it, and continue to react for 15 min to obtain solution A; (2) Accurately weigh 0.5 g of tris(hydroxymethyl)aminomethane powder, add it to 20 ml of an ethanol solution with a volume concentration of 99%, and stir until completely dissolved to obtain solution B; (3) Slowly add the obtained solution B to solution A, react for 5 h under the water bath conditions of 40°C and 600 r / min, and then obtain the SA-g-Tris hydrophile through centrifugal washing and freeze drying.

[0012] Further, the melt mixing is carried out in a torque rheometer under the conditions of 200°C and 100 r / min for 9 - 10 min.

[0013] Further, the injection molding is carried out in a micro injection molding machine under the conditions of 220°C and a pressure of 0.3 - 0.5 Mpa for 10 s and a holding pressure of 5 s.

[0014] The beneficial effects of the present invention are as follows: (1)Ethylene-vinyl alcohol copolymer is an olefinic thermoplastic with advantages such as high strength, strong thermal stability, high barrier property, and excellent hydrophilic property. In the present invention, adding ethylene-vinyl alcohol copolymer to polyethylene can solve the problems of poor barrier property and hydrophilic property of polyethylene. Meanwhile, the present invention adopts a high-temperature melt blending processing technology, which can uniformly disperse the ethylene-vinyl alcohol copolymer in polyethylene. Moreover, due to the different crystallization temperatures of ethylene-vinyl alcohol copolymer and high-density polyethylene, an island-like particle structure can be formed inside the polyethylene material during the crystallization process, further improving the mechanical properties of the material.

[0015] (2)In the SA-g-Tris hydrophile prepared in the present invention, on the one hand, due to the introduction of long carbon chains in stearic acid, the compatibility between the hydrophile and high-density polyethylene material is significantly improved. This not only ensures that the hydrophile can be better distributed evenly in the material, but also avoids the decline of mechanical properties. At the same time, the hydrophile relies on the amide bond with excellent chemical stability to connect the carbon chain and hydrophilic functional groups, significantly improving the thermal stability of the hydrophile; on the other hand, tris(hydroxymethyl)aminomethane itself contains multiple hydroxyl functional groups, which can ensure good toughening effect and excellent hydrophilic property. Meanwhile, under the synergistic effect of the polar groups of polyvinyl alcohol in ethylene-vinyl alcohol copolymer, the hydrophilic property and mechanical properties of high-density polyethylene pipes are further improved. In addition, the present invention uses EVA-g-MAH as a compatibilizer, which can further improve the compatibility between the hydrophile and polyethylene, and give full play to the hydrophilic and antifouling and toughening effects of the hydrophile.

[0016] (3)The processing technology for preparing high-density polyethylene pipes in the present invention is simple, only requiring simple hot processing for forming, and the raw materials are cheap and easily available.

[0017] (4)The water contact angle of the high-density polyethylene pipes prepared in the present invention is 33° - 39°, indicating that it has good hydrophilic and antifouling properties, and excellent mechanical properties. The tensile strength is 30.1 MPa - 33.5 MPa, the flexural strength is 16.3 MPa - 16.7 MPa, and the impact strength is 111 KJ / m 2 ~115 KJ / m 2 , and the elongation at break is 837% - 1058%. It can be widely used in the fields of domestic and industrial water supply pipelines, with significant economic value and social benefits. Description of the Drawings

[0018] Figure 1 It is the infrared absorption spectrogram of the SA-g-Tris hydrophile prepared in Example 1.

[0019] Figure 2 It is the cross-sectional morphology diagram of the high-density polyethylene composite antifouling pipe prepared in Example 1.

[0020] Figure 3 Schematic diagram of the contact angle of the high-density polyethylene composite anti-fouling pipe prepared in Example 1.

[0021] Figure 4 Cross-sectional morphology diagram of the polyethylene pipe prepared in Comparative Example 4. Detailed implementation manners

[0022] A SA-g-Tris toughened and modified HDPE hydrophilic anti-fouling pipe, and its preparation method includes the following steps: (1) Accurately weigh 1 g of stearic acid, add it to 20 ml of an ethanol solution with a volume concentration of 99%, stir it in a water bath at 40 °C and 600 r / min until completely dissolved, then slowly add 0.3 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide to the solution, after reacting for 5 min, slowly add 0.3 g of N-hydroxysuccinimide to it, and continue to react for 15 min to obtain solution A; (2) Accurately weigh 0.5 g of tris(hydroxymethyl)aminomethane powder, add it to 20 ml of an ethanol solution with a volume concentration of 99%, and stir until completely dissolved to obtain solution B; (3) Slowly add the obtained solution B to solution A, react for 5 h in a water bath at 40 °C and 600 r / min, then perform centrifugal washing and freeze-drying to obtain the SA-g-Tris hydrophile; (4) By weight, put 100 parts by weight of high-density polyethylene, 3 - 5 parts by weight of ethylene-vinyl alcohol copolymer, 1.5 - 2.5 parts by weight of EVA-g-MAH compatibilizer, and 2 - 4 parts by weight of SA-g-Tris hydrophile into a torque rheometer, knead at 200 °C and 100 r / min for 9 - 10 min, then crush it, dry it overnight in a vacuum drying oven, and then add it to a micro-injection molding machine, and stamp it at 220 °C and a pressure of 0.3 - 0.5 Mpa for 10 s, and hold the pressure for 5 s.

[0023] In order to make the content of the present invention easier to understand, the following further describes the technical solutions of the present invention in combination with specific implementation manners, but the present invention is not limited thereto.

[0024] The model of the high-density polyethylene used in the examples is 5000S, and its density is 0.941 - 0.960 g / cm³. The model of the ethylene-vinyl alcohol copolymer used is EW-3801. The model of the EVA-g-MAH compatibilizer used is Bynel39E660.

[0025] Example 1 The preparation steps of the SA-g-Tris toughened and modified high-density polyethylene composite anti-fouling pipe are as follows: (1) Accurately weigh 1 g of stearic acid and add it to 20 ml of 99% ethanol solution. Stir it in a water bath at 40 °C and 600 r / min until completely dissolved. Then slowly add 0.3 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide to the solution. After reacting for 5 min, slowly add 0.3 g of N-hydroxysuccinimide to it and continue reacting for 15 min to obtain solution A; (2) Accurately weigh 0.5 g of tris(hydroxymethyl)aminomethane powder and add it to 20 ml of 99% ethanol solution. Stir it until completely dissolved to obtain solution B; (3) Slowly add the obtained solution B to solution A. React for 5 h in a water bath at 40 °C and 600 r / min, then through centrifugal washing and freeze-drying, obtain the SA-g-Tris hydrophile; (4) Put 100 parts by weight of high-density polyethylene, 3 parts by weight of SA-g-Tris hydrophile, 2 parts by weight of EVA-g-MAH, and 4 parts by weight of ethylene-vinyl alcohol copolymer into a torque rheometer. Knead them at 200 °C and 100 r / min for 9 min. After pulverization, place them in a drying oven at 60 °C to dry overnight. Then add the obtained powder to a micro-injection molding machine. Set the mold temperature to 55 °C and stamp for 10 s at 220 °C and a pressure of 0.4 Mpa, and hold the pressure for 5 s to obtain a high-density polyethylene composite anti-fouling pipe toughened and modified by SA-g-Tris.

[0026] Figure 1 It is the infrared absorption spectrum of the SA-g-Tris hydrophile prepared in this example. As shown in the figure, compared with the infrared absorption spectrum of stearic acid, in the infrared absorption spectrum of the SA-g-Tris hydrophile, the absorption peaks at 1024 cm-1 and 3160 cm-1 corresponding to the OH stretching vibration are significantly enhanced, indicating that polar hydroxyl groups are grafted onto the stearic acid carbon chain; the absorption peaks at 1565 cm-1 and 3288 cm-1 corresponding to the N-H stretching vibration absorption peak and the absorption peak at 1637 cm-1 corresponding to the C=O stretching vibration absorption peak are also significantly enhanced; at the same time, the C=O absorption peak of stearic acid at 1698 cm-1 disappears, indicating that the carboxyl group in stearic acid participates in the reaction to synthesize an amide group during the synthesis process; in addition, compared with the infrared absorption spectrum of tris(hydroxymethyl)aminomethane, the absorption peak corresponding to the C-H stretching vibration of the SA-g-Tris hydrophile at 2918 cm-1 is significantly enhanced, indicating that a long carbon chain is grafted onto tris(hydroxymethyl)aminomethane, which can improve the compatibility and stability of the hydrophile.

[0027] Figure 2 It is the cross-sectional morphology diagram of the high-density polyethylene composite anti-fouling pipe prepared in this example. As shown in the figure, a large number of wire-drawing morphologies and particulate substances appear on the cross-section of the material, which all indicate that the toughness of the material has been enhanced.

[0028] Figure 3 This is a schematic diagram of the contact angle of the high-density polyethylene composite anti-fouling pipe prepared in this example. As shown in the figure, its static contact angle is only 33.5°, indicating that it has good hydrophilic properties.

[0029] Example 2 The preparation steps of the SA-g-Tris toughened and modified high-density polyethylene composite anti-fouling pipe are as follows: (1) Accurately weigh 1 g of stearic acid and add it to 20 ml of 99% ethanol solution. Stir it in a water bath at 40 °C and 600 r / min until it is completely dissolved. Then slowly add 0.3 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide to the solution. After reacting for 5 min, slowly add 0.3 g of N-hydroxysuccinimide to it and continue to react for 15 min to obtain solution A; (2) Accurately weigh 0.5 g of tris(hydroxymethyl)aminomethane powder and add it to 20 ml of 99% ethanol solution. Stir it until it is completely dissolved to obtain solution B; (3) Slowly add the obtained solution B to solution A and react it in a water bath at 40 °C and 600 r / min for 5 h. After centrifugal washing and freeze-drying, obtain the SA-g-Tris hydrophile; (4) Put 100 parts by weight of high-density polyethylene, 2 parts by weight of SA-g-Tris hydrophile, 1.5 parts by weight of EVA-g-MAH, and 3 parts by weight of ethylene-vinyl alcohol copolymer into a torque rheometer and knead them at 200 °C and 100 r / min for 9 min. After pulverization, put them into a drying oven at 60 °C and dry overnight. Then add the obtained powder to a micro-injection molding machine, set the mold temperature to 55 °C, and stamp it at 220 °C and a pressure of 0.4 Mpa for 10 s and hold the pressure for 5 s to obtain the SA-g-Tris toughened and modified high-density polyethylene composite anti-fouling pipe.

[0030] Example 3 The preparation steps of the SA-g-Tris toughened and modified high-density polyethylene composite anti-fouling pipe are as follows: (1) Accurately weigh 1 g of stearic acid and add it to 20 ml of 99% ethanol solution. Stir it in a water bath at 40 °C and 600 r / min until it is completely dissolved. Then slowly add 0.3 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide to the solution. After reacting for 5 min, slowly add 0.3 g of N-hydroxysuccinimide to it and continue to react for 15 min to obtain solution A; (2) Accurately weigh 0.5 g of tris(hydroxymethyl)aminomethane powder and add it to 20 ml of 99% ethanol solution. Stir it until it is completely dissolved to obtain solution B; (3) Slowly add the obtained solution B to solution A, react for 5 h under the water bath conditions of 40 °C and 600 r / min, and then obtain the SA-g-Tris hydrophile through centrifugal washing and freeze drying. (4) Put 100 parts by weight of high-density polyethylene, 4 parts by weight of SA-g-Tris hydrophile, 2.5 parts by weight of EVA-g-MAH, and 5 parts by weight of ethylene-vinyl alcohol copolymer into a torque rheometer, knead for 9 min under the conditions of 200 °C and 100 r / min, crush and then dry overnight in a 60 °C drying oven. Then add the obtained powder to a micro-injection molding machine, set the mold temperature to 55 °C, and stamp for 10 s under the conditions of 220 °C and a pressure of 0.4 Mpa, and hold the pressure for 5 s to obtain a high-density polyethylene composite anti-fouling pipe toughened and modified with SA-g-Tris.

[0031] Comparative Example 1 The preparation steps of the high-density polyethylene pipe are as follows: Put 100 parts by weight of high-density polyethylene into a torque rheometer, knead for 9 min under the conditions of 200 °C and 100 r / min, crush and then dry overnight in a 60 °C drying oven. Then add the obtained powder to a micro-injection molding machine, set the mold temperature to 55 °C, and stamp for 10 s under the conditions of 220 °C and a pressure of 0.4 Mpa, and hold the pressure for 5 s to obtain a high-density polyethylene pipe.

[0032] Figure 4 This is the cross-sectional morphology diagram of the high-density polyethylene fouling pipe prepared in this comparative example. It can be seen from the figure that its cross-section does not show an obvious drawn state and particulate matter.

[0033] The static contact angle of the high-density polyethylene fouling pipe prepared in this comparative example is 116.9°.

[0034] Comparative Example 2 The preparation steps of the high-density polyethylene composite anti-fouling pipe modified with tris(hydroxymethyl)aminomethane are as follows: Put 100 parts by weight of high-density polyethylene, 3 parts by weight of tris(hydroxymethyl)aminomethane, 4 parts by weight of ethylene-vinyl alcohol copolymer, and 2 parts by weight of EVA-g-MAH into a torque rheometer, knead for 9 min under the conditions of 200 °C and 100 r / min, crush and then dry overnight in a 60 °C drying oven. Then add the obtained powder to a micro-injection molding machine, set the mold temperature to 55 °C, and stamp for 10 s under the conditions of 220 °C and a pressure of 0.4 Mpa, and hold the pressure for 5 s to obtain a high-density polyethylene composite anti-fouling pipe modified with tris(hydroxymethyl)aminomethane.

[0035] Comparative Example 3 The preparation steps of the high-density polyethylene composite anti-fouling pipe modified with span are as follows: 100 parts by weight of high-density polyethylene, 3 parts by weight of Span 80, 2 parts by weight of EVA-g-MAH, and 4 parts by weight of ethylene-vinyl alcohol copolymer were put into a torque rheometer and kneaded at 200 °C and 100 r / min for 9 min. After being pulverized, they were placed in a drying oven at 60 °C and dried overnight. Then the obtained powder was added to a micro-injection molding machine, the mold temperature was set at 55 °C, and it was stamped at 220 °C and a pressure of 0.4 Mpa for 10 s and held the pressure for 5 s to obtain a Span-modified high-density polyethylene composite anti-fouling pipe.

[0036] Comparative Example 4 The preparation steps of the SA-g-Tris toughened and modified high-density polyethylene composite anti-fouling pipe are as follows: (1) Accurately weigh 1 g of stearic acid, add it to 20 ml of 99% ethanol solution, stir it in a water bath at 40 °C and 600 r / min until it is completely dissolved. Then slowly add 0.3 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide to the solution, and after reacting for 5 min, slowly add 0.3 g of N-hydroxysuccinimide to it and continue to react for 15 min to obtain solution A; (2) Accurately weigh 0.5 g of tris(hydroxymethyl)aminomethane powder, add it to 20 ml of 99% ethanol solution, and stir until it is completely dissolved to obtain solution B; (3) Slowly add the obtained solution B to solution A, react it in a water bath at 40 °C and 600 r / min for 5 h, then carry out centrifugal washing and freeze-drying to obtain the SA-g-Tris hydrophile; (4) 100 parts by weight of high-density polyethylene, 3 parts by weight of the SA-g-Tris hydrophile, and 2 parts by weight of EVA-g-MAH were put into a torque rheometer and kneaded at 200 °C and 100 r / min for 9 min. After being pulverized, they were placed in a drying oven at 60 °C and dried overnight. Then the obtained powder was added to a micro-injection molding machine, the mold temperature was set at 55 °C, and it was stamped at 220 °C and a pressure of 0.4 Mpa for 10 s and held the pressure for 5 s to obtain the SA-g-Tris toughened and modified high-density polyethylene composite anti-fouling pipe.

[0037] Comparative Example 5 The preparation steps of the hydrophile toughened and modified high-density polyethylene composite anti-fouling pipe are as follows: (1) Accurately weigh 1 g of stearic acid and add it to 20 ml of 99% ethanol solution. Stir it in a water bath at 40 °C and 600 r / min until it is completely dissolved. Then slowly add 0.2 g of dicyclohexylcarbodiimide to the solution. After reacting for 5 min, slowly add 0.5 g of tris(hydroxymethyl)aminomethane powder and stir until it is completely dissolved. Then react it in a water bath at 40 °C and 600 r / min for 5 h. After centrifugal washing and freeze-drying, a hydrophilizing agent is obtained.

[0038] (2) Put 100 parts by weight of high-density polyethylene, 3 parts by weight of hydrophilizing agent, 2 parts by weight of EVA-g-MAH, and 4 parts by weight of ethylene-vinyl alcohol copolymer into a torque rheometer and knead them at 200 °C and 100 r / min for 9 min. After pulverization, put them into a drying oven at 60 °C and dry overnight. Add the obtained powder to a micro-injection molding machine, set the mold temperature at 55 °C, and stamp it at 220 °C and a pressure of 0.4 Mpa for 10 s and hold the pressure for 5 s to obtain a high-density polyethylene composite anti-fouling pipe toughened and modified by a hydrophilizing agent.

[0039] For the finished products prepared in the examples and comparative examples, conduct water contact angle tests according to GB / T 30693-2014; conduct flexural strength tests according to the test method of GB / T9341-2008; conduct impact strength tests according to the test method of ISO179-1:2000; conduct tensile strength and elongation at break tests according to the test method of GB / T 1040.2-2006. The results are shown in Table 1.

[0040] Table 1 Performance test results

[0041] It can be seen from the results in Table 1 that compared with the materials obtained in the comparative examples, the hydrophilic properties and toughness of the materials prepared in the examples have been significantly improved, proving that the prepared high-density polyethylene pipes have excellent hydrophilic anti-fouling properties and mechanical properties. Among them, the SA-g-Tris toughened and modified high-density polyethylene composite anti-fouling pipe prepared in Example 1 has the best performance.

[0042] The above are only the preferred embodiments of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope covered by the present invention.

Claims

1. A method for preparing an SA-g-Tris toughened and modified HDPE composite anti-fouling pipe, characterized in that: The HDPE hydrophilic and anti-fouling pipe is prepared from high-density polyethylene, ethylene-vinyl alcohol copolymer, EVA-g-MAH compatibilizer, and SA-g-Tris hydrophilizing agent through melt mixing, pulverizing, drying, and injection molding.

2. The method for preparing a high-density polyethylene composite anti-fouling pipe by toughening and modifying with SA-g-Tris according to claim 1, characterized in that: The raw materials are as follows by weight: 100 parts by weight of high-density polyethylene, 3 - 5 parts by weight of ethylene-vinyl alcohol copolymer, 1.5 - 2.5 parts by weight of EVA-g-MAH compatibilizer, and 2 - 4 parts by weight of SA-g-Tris hydrophilizing agent.

3. The method for preparing a high-density polyethylene composite anti-fouling pipe by toughening and modifying with SA-g-Tris according to claim 1 or 2, characterized in that: The model of the high-density polyethylene is 5000S, and its density is 0.941 - 0.960 g / cm³.

4. The method for preparing a high-density polyethylene composite anti-fouling pipe by toughening modification with SA-g-Tris according to claim 1 or 2, characterized in that: The model of the ethylene-vinyl alcohol copolymer is EW-3801.

5. The method for preparing a high-density polyethylene composite anti-fouling pipe by toughening and modifying with SA-g-Tris according to claim 1 or 2, characterized in that: The model of the EVA-g-MAH compatibilizer is Bynel 39E660.

6. The method for preparing a high-density polyethylene composite anti-fouling pipe by toughening and modifying with SA-g-Tris according to claim 1 or 2, characterized in that: The preparation method of the SA-g-Tris hydrophilizing agent includes the following steps: (1) Accurately weigh 1 g of stearic acid, add it to 20 ml of an ethanol solution with a volume concentration of 99%, stir it in a water bath at 40°C and 600 r / min until completely dissolved, then slowly add 0.3 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide to the solution. After reacting for 5 min, slowly add 0.3 g of N-hydroxysuccinimide to it and continue to react for 15 min to obtain solution A; (2) Accurately weigh 0.5 g of tris(hydroxymethyl)aminomethane powder, add it to 20 ml of an ethanol solution with a volume concentration of 99%, and stir until completely dissolved to obtain solution B; (3) Slowly add the obtained solution B to solution A, react for 5 h in a water bath at 40°C and 600 r / min, and then obtain the SA-g-Tris hydrophilizing agent through centrifugal washing and freeze-drying.

7. The method for preparing a high-density polyethylene composite anti-fouling pipe by toughening and modifying with SA-g-Tris according to claim 1, characterized in that: The melt mixing is carried out in a torque rheometer at 200°C and 100 r / min for 9 - 10 min.

8. The method for preparing a high-density polyethylene composite anti-fouling pipe by toughening and modifying with SA-g-Tris according to claim 1, characterized in that: The injection molding is carried out in a micro injection molding machine at 220°C and a pressure of 0.3 - 0.5 Mpa for 10 s, with a holding pressure of 5 s.

9. A high-density polyethylene composite anti-fouling pipe prepared by the method as described in claim 1.

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