Betulin polyurethane elastomer reinforced HDPE (high-density polyethylene) composite material and preparation method thereof

Abstract

The invention relates to the technical field of high-density polyethylene composite materials, in particular to a betulin polyurethane elastomer reinforced HDPE composite material and a preparation method thereof. According to the method disclosed by the invention, the betulin polyurethane elastomer is prepared, the HDPE composite material is reinforced by the betulin polyurethane elastomer, and the betulin polyurethane elastomer takes hexamethylene diisocyanate as a hard segment and betulin and polyethylene glycol as soft segments; by introducing the betulin polyurethane elastomer into the HDPE matrix, the comprehensive performance of the HDPE can be effectively improved, so that the high-strength and high-toughness composite material is obtained, and the composite material has higher stability and durability in a complex environment. The preparation method of the betulin polyurethane elastomer is simple and can be used for large-scale production; meanwhile, the prepared betulin polyurethane elastomer reinforced high-density polyethylene composite material is high in cost performance and is expected to be applied to the field of high-performance pipeline materials on a large scale.

Description

Technical Field

[0001] The invention relates to the technical field of high-density polyethylene composite materials, and in particular to a betulin polyurethane elastomer-reinforced HDPE composite material and a preparation method thereof. Background Art

[0002] High-density polyethylene (HDPE), as a commonly used thermoplastic, has excellent mechanical properties, chemical stability, corrosion resistance, and is easy to process with low cost. It is widely used in pipelines, packaging, automobiles, home appliances and other fields.

[0003] Although HDPE performs well in many application scenarios, in certain specific occasions, especially in areas that require high strength, impact resistance, and flexibility, the performance of HDPE materials is still insufficient, limiting its further expansion in specific areas. Currently, there are modification methods such as adding reinforcing agents, blending modification, and changing material structure to improve the mechanical properties of HDPE materials, but some additives such as glass fibers and carbon nanotubes often lead to reduced toughness when improving the strength of HDPE composite materials, and at the same time, reduced processing performance, resulting in poor performance in pipeline applications.

[0004] Betulin is a natural compound extracted from birch bark, a pentacyclic triterpenoid compound, containing multiple hydroxyl groups (3 primary hydroxyl groups), and can be used as a polyol to synthesize polyurethane. Polyurethane elastomers based on betulin have excellent strength, toughness, impact resistance and low temperature resistance, and can effectively improve the comprehensive mechanical properties of composite materials. The present invention provides a HDPE composite material reinforced by betulin polyurethane elastomer and a preparation method thereof, so as to solve the deficiencies in the prior art and provide a new material with broad application prospects in the fields of high-performance pipeline materials and the like. Summary of the invention

[0005] The purpose of the present invention is to provide a betulin polyurethane elastomer reinforced HDPE composite material and a preparation method thereof, so as to solve the problem that the strength and toughness of the existing HDPE modified materials cannot be taken into account at the same time, which limits the application of the HDPE composite material.

[0006] To achieve the above purpose, the present invention adopts the following technical scheme: a betulin polyurethane elastomer reinforced HDPE composite material, wherein the raw materials include the following components in parts by weight: 60 to 80 parts of high-density polyethylene, 10 to 30 parts of betulin polyurethane elastomer, 1 to 5 parts of nanofiller, 2 to 6 parts of compatibilizer, 1 to 5 parts of plasticizer, 0.5 to 3 parts of lubricant, 0.5 to 3 parts of antioxidant, 0.5 to 2 parts of coupling agent, 0.5 to 3 parts of heat stabilizer, 0.5 to 3 parts of light stabilizer and 0.5 to 2 parts of pigment.

[0007] Furthermore, the preparation method of the betulin polyurethane elastomer is as follows: By the one-pot method, dissolve betulin and polyethylene glycol (PEG) in an organic solvent, add hexamethylene diisocyanate (HDI) under a protective atmosphere, then add a catalyst, heat and react, and after casting and drying and curing, the betulin polyurethane elastomer of the present invention can be obtained.

[0008] Furthermore, the molecular weight of the polyethylene glycol is 200 - 600; the organic solvent is one of N,N-dimethylformamide (DMF) and tetrahydrofuran (THF). After adding the organic solvent, it is vacuum dried at 80°C for 4 hours with a vacuum degree of 0.01 Mpa to remove moisture; after adding the organic solvent, vacuum is pumped at room temperature for 30 min, and then at 85°C for 20 min with a vacuum degree of 0.01 Mpa to remove the air in the system.

[0009] Furthermore, the molar ratio of the betulin monomer, polyethylene glycol and hexamethylene diisocyanate is 2:1:3 - 6.

[0010] Furthermore, the catalyst is dibutyltin dilaurate or organic bismuth, and is 0.1 - 0.8 wt% of the total solute mass.

[0011] Furthermore, the protective atmosphere is nitrogen; the heating reaction temperature is 70 - 90°C, and the reaction time is 2 - 5 h.

[0012] Furthermore, the casting mold is a polytetrafluoroethylene mold, the drying and curing temperature is 70 - 90°C, and the volatilization time is 24 - 36 h.

[0013] Furthermore, the tensile strength of the betulin polyurethane elastomer can reach 46.1 MPa, the elongation at break can reach 753%, and the notched impact strength can reach 10.12 kJ / m 2 .

[0014] Furthermore, the nano filler is one or more of montmorillonite, nano calcium carbonate, copper nanoparticles, etc.; the compatibilizer is one or more of maleic anhydride grafted PE, maleic anhydride grafted POE, maleic anhydride grafted EVA, etc.; the plasticizer is one or more of ethylene-vinyl acetate (EVA), polyisobutylene (PIB), epoxy soybean oil, diisooctyl phthalate, etc.; the lubricant is one or more of polyethylene wax, paraffin wax, stearic acid, etc.; the antioxidant is one or more of phosphite, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], etc.; the coupling agent is a silane coupling agent; the heat stabilizer is one or more of mercapto methyltin, hydrotalcite (LDH), calcium stearate, etc.; the light stabilizer is one or more of benzotriazole, benzophenone, zinc oxide, etc.; the pigment is one or more of iron oxide brown, titanium dioxide, etc.

[0015] Preparation method of betulinol polyurethane elastomer-reinforced HDPE composite material, comprising the following steps:

[0016] S1. Mix high-density polyethylene, betulinol polyurethane elastomer, compatibilizer, lubricant, and coupling agent evenly;

[0017] The above-mentioned mixing is carried out in a pulverizer by stirring at 1000 r / min for 1 to 3 minutes;

[0018] S2. Subsequently, add nano-filler, plasticizer, antioxidant, heat stabilizer, light stabilizer, and pigment, and mix evenly to obtain a mixture;

[0019] Each time a raw material is added, it is stirred at 1000 r / min for 1 to 3 minutes until evenly mixed;

[0020] S3. Extrude and pelletize the mixture;

[0021] The process parameters of the above-mentioned extrusion are as follows: a twin-screw extruder is adopted, the temperature of the first zone of the twin-screw extruder is 160 - 170 °C, the second zone is 170 - 190 °C, the third zone is 180 - 200 °C, the fourth zone is 190 - 210 °C, the residence time is 1 - 2 min, the pressure is 5 - 15 MPa, the rotation speed is 20 - 100 r / min, and the traction speed is 0.5 - 5 m / min.

[0022] Advantages of the present invention:

[0023] (1) The synthesis method of the betulinol polyurethane elastomer required by the present invention is simple, other raw materials are cheap and easy to obtain, the process operation is simple, and it can be prepared in large quantities for large-scale production. Among them, betulinol is a bio-based material, a natural pentacyclic triterpenoid compound, which is green and environmentally friendly;

[0024] (2) The betulinol polyurethane elastomer-reinforced high-density polyethylene composite material prepared by the present invention has excellent tensile strength and good toughness; betulinol in the polyurethane has a rigid pentacyclic triterpene structure, providing a high hard segment content, significantly improving the modulus and tensile strength; and the present invention can adjust the strength and toughness of the HDPE composite material by changing the ratio of hard and soft segments in the molecular chain of the polyurethane elastomer through molecular structure design;

[0025] (3) The betulinol polyurethane elastomer-reinforced high-density polyethylene composite material prepared by the present invention has a high cost performance. Therefore, the prepared high-density polyethylene composite material is expected to be widely used in the field of high-performance pipeline materials. Specific embodiments

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention.

[0027] The principle of the present invention is:

[0028] Betulinol polyurethane elastomer uses hexamethylene diisocyanate as the hard segment, and betulinol and polyethylene glycol as the soft segment. The polyurethane elastomer is synthesized by a one-pot reaction method. This synthesis method is simple and can be produced on a large scale.

[0029] By introducing betulinol polyurethane elastomer into the HDPE matrix, the comprehensive properties of HDPE can be effectively improved. Especially after blending and compounding HDPE with betulinol polyurethane elastomer, the tensile strength and flexural strength of the composite material can be improved, so as to obtain a high-strength and high-toughness composite material, making the composite material have higher stability and durability in complex environments.

[0030] At the same time, the strength and toughness of the HDPE composite material can be further designed by changing the equivalent ratio of the hard and soft segments in the molecular chain of the betulinol polyurethane elastomer. The ratio of the hard segment to the soft segment is 1-2:1, and the molecular weight of polyethylene glycol is 200-600 to ensure the mechanical properties of the betulinol polyurethane elastomer.

[0031] Examples of the present invention:

[0032] Materials used in the examples of the present invention: Betulinol, with a specification of ≥98%, from Macklin; Ethylene glycol, with a specification of 98% and a molecular weight of 200, from Macklin; DMF, with a specification of analytical pure, from Aladdin Reagent Co., Ltd.; Hexamethylene diisocyanate, with a specification of 99%, from Macklin; Dibutyltin dilaurate, from Aladdin Reagent Co., Ltd.; High-density polyethylene, with a melt index of 12 g / 10 min, from Aladdin Reagent Co., Ltd.; Calcium carbonate, from Aladdin Reagent Co., Ltd.; Maleic anhydride grafted polyethylene, with a grafting rate of 8%, from Aladdin Reagent Co., Ltd.; Diisooctyl phthalate (DOP), reagent grade, 95%, from Macklin; Polyethylene wax, Mn 2000-3000, from Macklin; Triphenyl phosphite, 97%, from Macklin; Silane coupling agent (vinyltriethoxysilane), from Aladdin Reagent Co., Ltd.; Mercaptomethyltin, Sn: 19%, from Aladdin Reagent Co., Ltd.; Benzophenone, chemically pure, from Aladdin Reagent Co., Ltd.; Iron oxide brown, CAS: 52357-70-7, purchased commercially.

[0033] In the examples of the present invention, the betulinol polyurethane elastomer is prepared by the following method:

[0034] Dissolve betulinol (3157.64 mg, 7.1324 mmol) and PEG 200 (713.20 mg, 3.5662 mmol) in 13 mL of DMF. After complete dissolution, evacuate at room temperature for 30 min and at 85 °C for 20 min, with a vacuum degree of 0.01 Mpa; under N 2Quickly add hexamethylene diisocyanate (2285 μL, 14.2648 mmol) under the atmosphere; before adding hexamethylene diisocyanate, vacuum dry at 80 °C and a vacuum of 0.01 Mpa for 4 h to remove the moisture therein; then add 30 μL of dibutyltin dilaurate catalyst, and stir and react at 80 °C and 100 rpm for 3 h; dry in a forced-air drying oven at 80 °C for 36 h to volatilize the solvent to complete crosslinking and curing, and obtain betulin polyurethane elastomer Betulin-PU.

[0035] Using PEG 200 When, the structural formula of Betulin-PU of the present invention is:

[0036]

[0037] In this structural formula, due to the use of PEG 200 , the polymerization degree corresponding to polyethylene glycol in the elastomer is 5. When polyethylene glycol with other molecular weights is used, this value changes accordingly. In this elastomer, the ratio of hard segment to soft segment is 1-2:1 (the ratio of the molar amount of materials added), and the end group is -NCO; after testing, the tensile strength of the betulin polyurethane elastomer can reach 46.1 MPa, the elongation at break can reach 753%, and the notch impact strength can reach 10.12 kJ / m 2 .

[0038] Example 1

[0039] Prepare a high-density polyethylene composite material reinforced with betulin polyurethane elastomer according to the following weight ratio: 60 parts of high-density polyethylene, 20 parts of betulin polyurethane elastomer, 3 parts of nano calcium carbonate, 5 parts of maleic anhydride grafted polyethylene, 5 parts of diisooctyl phthalate, 0.5 part of polyethylene wax, 0.5 part of triphenyl phosphite, 2 parts of silane coupling agent, 3 parts of mercapto methyltin, 0.5 part of benzophenone, 0.5 part of iron oxide brown.

[0040] Adopt the following preparation method:

[0041] a. Weigh each raw material according to the ratio and set aside. Add five raw materials of high-density polyethylene, betulin polyurethane elastomer, maleic anhydride grafted polyethylene (compatibilizer), polyethylene wax (lubricant), and silane coupling agent (coupling agent) to a multi-functional grinder and stir at 1000 r / min for 3 min until evenly mixed;

[0042] b. Subsequently, add nano calcium carbonate (nano filler), diisooctyl phthalate (plasticizer), triphenyl phosphite (antioxidant), mercapto methyltin (heat stabilizer), benzophenone (light stabilizer), and iron oxide brown (pigment) in sequence. Stir at 1000 r / min for 3 min until evenly mixed for each added raw material;

[0043] c. Finally, add the mixture into the barrel of a twin-screw extruder, heat and mix it, and then extrude and pelletize it.

[0044] Among them, the processing parameters of the twin-screw extruder are as follows:

[0045] The temperature of the first zone of the twin-screw extruder is 160 °C, the second zone is 175 °C, the third zone is 185 °C, the fourth zone is 195 °C, the residence time is 2 min, the pressure is 10 MPa, the rotation speed is 30 r / min, and the traction speed is 2 m / min.

[0046] Example 2

[0047] Prepare a high-density polyethylene composite reinforced with betulin polyurethane elastomer with the following weight ratios: 65 parts of high-density polyethylene, 15 parts of betulin polyurethane elastomer, 3 parts of nano calcium carbonate, 5 parts of maleic anhydride grafted polyethylene, 5 parts of diisooctyl phthalate, 0.5 part of polyethylene wax, 0.5 part of triphenyl phosphite, 2 parts of silane coupling agent, 3 parts of mercaptomethyltin, 0.5 part of benzophenone, and 0.5 part of iron oxide brown.

[0048] Adopt the following preparation method:

[0049] a. Weigh each raw material according to the ratio and set it aside. Add five raw materials, namely high-density polyethylene, betulin polyurethane elastomer, maleic anhydride grafted polyethylene (compatibilizer), polyethylene wax (lubricant), and silane coupling agent (coupling agent), into a multi-functional pulverizer and stir at 1000 r / min for 3 min until evenly mixed;

[0050] b. Subsequently, add nano calcium carbonate (nano filler), diisooctyl phthalate (plasticizer), triphenyl phosphite (antioxidant), mercaptomethyltin (heat stabilizer), benzophenone (light stabilizer), and iron oxide brown (pigment) in sequence. Stir at 1000 r / min for 3 min until evenly mixed after adding each raw material;

[0051] c. Finally, add the mixture into the barrel of a twin-screw extruder, heat and mix it, and then extrude and pelletize it.

[0052] Among them, the processing parameters of the twin-screw extruder are as follows:

[0053] The temperature of the first zone of the twin-screw extruder is 165 °C, the second zone is 180 °C, the third zone is 190 °C, the fourth zone is 195 °C, the residence time is 2 min, the pressure is 10 MPa, the rotation speed is 30 r / min, and the traction speed is 2 m / min.

[0054] Example 3

[0055] Prepare a high-density polyethylene composite reinforced with betulin polyurethane elastomer using the following weight ratios: 70 parts of high-density polyethylene, 10 parts of betulin polyurethane elastomer, 3 parts of nano calcium carbonate, 5 parts of maleic anhydride grafted polyethylene, 5 parts of diisooctyl phthalate, 0.5 part of polyethylene wax, 0.5 part of triphenyl phosphite, 2 parts of silane coupling agent, 3 parts of mercapto methyltin, 0.5 part of benzophenone, and 0.5 part of iron oxide brown.

[0056] Use the following preparation method:

[0057] a. Weigh each raw material according to the ratio and set aside. Add five raw materials, namely high-density polyethylene, betulin polyurethane elastomer, maleic anhydride grafted polyethylene (compatibilizer), polyethylene wax (lubricant), and silane coupling agent (coupling agent), into a multi-functional pulverizer and stir at 1000 r / min for 3 min until evenly mixed.

[0058] b. Subsequently, add nano calcium carbonate (nano filler), diisooctyl phthalate (plasticizer), triphenyl phosphite (antioxidant), mercapto methyltin (heat stabilizer), benzophenone (light stabilizer), and iron oxide brown (pigment) in sequence. Stir at 1000 r / min for 3 min until evenly mixed after adding each raw material.

[0059] c. Finally, add the mixture into the barrel of a twin-screw extruder, heat and mix, and then extrude and pelletize.

[0060] Among them, the processing parameters of the twin-screw extruder are as follows:

[0061] The temperature of the first zone of the twin-screw extruder is 170 °C, the second zone is 185 °C, the third zone is 200 °C, the fourth zone is 205 °C, the residence time is 2 min, the pressure is 10 MPa, the rotation speed is 30 r / min, and the traction speed is 2 m / min.

[0062] Comparative Example 1

[0063] Prepare a glass fiber-reinforced high-density polyethylene composite using the following weight ratios: 60 parts of high-density polyethylene, 20 parts of glass fiber, 3 parts of nano calcium carbonate, 5 parts of maleic anhydride grafted polyethylene, 5 parts of diisooctyl phthalate, 0.5 part of polyethylene wax, 0.5 part of triphenyl phosphite, 2 parts of silane coupling agent, 3 parts of mercapto methyltin, 0.5 part of benzophenone, and 0.5 part of iron oxide brown.

[0064] In the comparative example, the common HDPE reinforcing agent glass fiber was used to replace the betulin polyurethane elastomer.

[0065] Use the following preparation method:

[0066] a. Weigh each raw material according to the proportion and set it aside. Add five raw materials, namely high-density polyethylene, glass fiber, maleic anhydride grafted polyethylene (compatibilizer), polyethylene wax (lubricant), and silane coupling agent (coupling agent), into a multi-functional grinder and stir at 1000 r / min for 3 min until evenly mixed.

[0067] b. Subsequently, add nano calcium carbonate (nano filler), diisooctyl phthalate (plasticizer), triphenyl phosphite (antioxidant), mercapto methyl tin (heat stabilizer), benzophenone (light stabilizer), and iron oxide brown (pigment) in sequence. Stir at 1000 r / min for 3 min until evenly mixed each time a raw material is added.

[0068] c. Finally, add the mixture into the barrel of a twin-screw extruder, heat and mix it, and then extrude and pelletize.

[0069] Among them, the processing parameters of the twin-screw extruder are as follows:

[0070] The temperature of the first zone of the twin-screw extruder is 160 °C, the second zone is 175 °C, the third zone is 185 °C, the fourth zone is 195 °C, the residence time is 2 min, the pressure is 10 MPa, the rotation speed is 30 r / min, and the traction speed is 2 m / min.

[0071] Comparative Example 2

[0072] Prepare a high-density polyethylene composite toughened with methyl methacrylate-butadiene-styrene copolymer (MBS) using the following weight ratio: 60 parts of high-density polyethylene, 20 parts of MBS, 3 parts of nano calcium carbonate, 5 parts of maleic anhydride grafted polyethylene, 5 parts of diisooctyl phthalate, 0.5 part of polyethylene wax, 0.5 part of triphenyl phosphite, 2 parts of silane coupling agent, 3 parts of mercapto methyl tin, 0.5 part of benzophenone, and 0.5 part of iron oxide brown.

[0073] In the comparative example, the common HDPE toughening agent MBS was used to replace betulin polyurethane elastomer.

[0074] Adopt the following preparation method:

[0075] a. Weigh each raw material according to the proportion and set it aside. Add five raw materials, namely high-density polyethylene, MBS, maleic anhydride grafted polyethylene (compatibilizer), polyethylene wax (lubricant), and silane coupling agent (coupling agent), into a multi-functional grinder and stir at 1000 r / min for 3 min until evenly mixed.

[0076] b. Subsequently, add nano calcium carbonate (nano filler), diisooctyl phthalate (plasticizer), triphenyl phosphite (antioxidant), mercapto methyl tin (heat stabilizer), benzophenone (light stabilizer), and iron oxide brown (pigment) in sequence. Stir at 1000 r / min for 3 min until evenly mixed each time a raw material is added.

[0077] c. Finally, add the mixture into the barrel of a twin-screw extruder, heat and mix it, and then extrude and pelletize it.

[0078] Among them, the processing process parameters of the twin-screw extruder are as follows:

[0079] The temperature of the first zone of the twin-screw extruder is 160 °C, the second zone is 175 °C, the third zone is 185 °C, the fourth zone is 195 °C, the residence time is 2 min, the pressure is 10 MPa, the rotation speed is 30 r / min, and the traction speed is 2 m / min.

[0080] The test results of the properties of the composite materials prepared in Examples 1-3 and Comparative Examples 1-2 are shown in Table 1.

[0081] Table 1 Performance test table of high-density polyethylene composite materials

[0082]

[0083] Conclusion: The high-density polyethylene composite material reinforced by betulinol polyurethane elastomer provided by the present invention has excellent tensile strength, toughness, and impact strength, is comparable to the high-density polyethylene composite material reinforced by glass fiber, and the toughness is improved; although the high-density polyethylene composite material toughened with MBS has relatively high toughness and impact strength, its strength is poor.

[0084] The high-density polyethylene composite material reinforced by betulinol polyurethane elastomer provided by the present invention overcomes the limitations in the prior art, significantly improves the strength of HDPE, takes into account good toughness, and is especially suitable for fields such as high-performance pipeline materials; through a simple synthesis process, this composite material has good cost performance, can meet the requirements of high strength and durability in complex environments, and has broad application prospects.

[0085] The present invention is not limited to the above best implementation manner. Anyone can obtain other various forms of products under the inspiration of the present invention. However, no matter what changes are made in its shape or structure, as long as it has the same or similar technical solutions as this application, they all fall within the protection scope of the present invention.

Claims

1. A HDPE composite material reinforced with betulin polyurethane elastomer, characterized in that: The raw materials include the following components in parts by weight: 60-80 parts of high-density polyethylene, 10-30 parts of betulin polyurethane elastomer, 1-5 parts of nano filler, 2-6 parts of volume extender, 1-5 parts of plasticizer, 0.5-3 parts of lubricant, 0.5-3 parts of antioxidant, 0.5-2 parts of coupling agent, 0.5-3 parts of heat stabilizer, 0.5-3 parts of light stabilizer and 0.5-2 parts of pigment.

2. The betulin polyurethane elastomer reinforced HDPE composite material according to claim 1, characterized in that: The preparation method of the betulin polyurethane elastomer is as follows: betulin and polyethylene glycol are dissolved in an organic solvent by a one-pot method, hexamethylene diisocyanate is added under a protective atmosphere, and then a catalyst is added, heated to react, and then cast, dried and solidified to obtain the betulin polyurethane elastomer of the present invention.

3. The betulin polyurethane elastomer reinforced HDPE composite material according to claim 2, characterized in that: The molecular weight of the polyethylene glycol is 200-600; the organic solvent is one of N,N-dimethylformamide and tetrahydrofuran, and the organic solvent is vacuum dried at 80°C for 4 hours with a vacuum degree of 0.01Mpa before being added to remove moisture; after betulin and polyethylene glycol are dissolved in the organic solvent, vacuum is drawn at room temperature for 30 minutes, and then vacuum is drawn at 85°C for 20 minutes with a vacuum degree of 0.01Mpa to remove air in the system.

4. The betulin polyurethane elastomer reinforced HDPE composite material according to claim 3, characterized in that: The molar ratio of the betulin monomer, polyethylene glycol and hexamethylene diisocyanate is 2:1:3-6.

5. The betulin polyurethane elastomer reinforced HDPE composite material according to claim 4, characterized in that: The catalyst is dibutyltin dilaurate or organic bismuth, which accounts for 0.1-0.8wt% of the total solute mass.

6. The betulin polyurethane elastomer reinforced HDPE composite material according to claim 2, characterized in that: The protective atmosphere is nitrogen; the heating reaction temperature is 70-90° C., and the reaction time is 2-5 hours.

7. The betulin polyurethane elastomer reinforced HDPE composite material according to claim 2, characterized in that: The casting mold is a polytetrafluoroethylene mold, the drying and curing temperature is 70-90° C., and the volatilization time is 24-36 hours.

8. The betulin polyurethane elastomer reinforced HDPE composite material according to claim 2, characterized in that: The tensile strength of the betulin polyurethane elastomer can reach 46.1MPa, the elongation at break can reach 753%, and the notched impact strength can reach 10.12kJ / m 2 .

9. The betulin polyurethane elastomer reinforced HDPE composite material according to claim 1, characterized in that: The nano filler is one or more of montmorillonite, nano calcium carbonate, and copper nano particles; the compatibilizer is one or more of maleic anhydride grafted PE, maleic anhydride grafted POE, and maleic anhydride grafted EVA; the plasticizer is one or more of ethylene vinyl acetate, polyisobutylene, epoxy soybean oil, and diisooctyl phthalate; the lubricant is one or more of polyethylene wax, paraffin, and stearic acid; the antioxidant is one or more of phosphite and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate; the coupling agent is a silane coupling agent; the heat stabilizer is one or more of methyl tin mercaptan, hydrotalcite, and calcium stearate; the light stabilizer is one or more of benzotriazole, benzophenone, and zinc oxide; and the pigment is one or more of iron oxide brown and titanium dioxide.

10. The method for preparing the HDPE composite material reinforced with betulin polyurethane elastomer according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. Mix high-density polyethylene, betulin polyurethane elastomer, compatibilizer, lubricant and coupling agent; The mixing is carried out in a pulverizer at 1000 r / min for 1 to 3 minutes; S2, then add nanofiller, plasticizer, antioxidant, heat stabilizer, light stabilizer, pigment, mix well, and obtain a mixture; Each time a raw material is added, stir at 1000r / min for 1 to 3 minutes until it is evenly mixed; S3, extruding and granulating the mixture; The extrusion process parameters are: using a twin-screw extruder, the temperature of the first zone of the twin-screw extruder is 160-170°C, the second zone is 170-190°C, the third zone is 180-200°C, the fourth zone is 190-210°C, the residence time is 1-2min, the pressure is 5-15MPa, the rotation speed is 20-100r / min, and the traction speed is 0.5-5m / min.

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