Polyethylene wax modified polypropylene material and preparation method thereof

Abstract

The invention belongs to the technical field of high-performance polypropylene, and particularly relates to a polyethylene wax modified polypropylene material and a preparation method thereof. The invention aims to solve the problems of poor mechanical properties and poor aging resistance of the existing polyethylene wax-polypropylene composite material. The preparation method comprises the following steps: performing in-situ polymerization grafting on a polyethylene wax raw material to obtain prefabricated polyethylene wax; melting and mixing the functional filler and the prefabricated polyethylene wax to obtain modified polyethylene wax; carrying out reaction mixing on polypropylene resin and modified polyethylene wax to obtain modified polypropylene; carrying out oxidation modification on a polyethylene wax raw material to obtain main body polyethylene wax; performing in-situ reaction extrusion on the main body polyethylene wax, the cross-linking agent and the modified polypropylene to obtain composite polypropylene; and carrying out high-temperature solid-phase post-treatment on the composite polypropylene to obtain the polyethylene wax modified polypropylene material. The polyethylene wax modified polypropylene material prepared by the invention has good toughness and mechanical strength, and also has excellent aging resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of high-performance polypropylene, and in particular relates to a polyethylene wax-modified polypropylene material and a preparation method thereof. Background Art

[0002] Polypropylene is a versatile thermoplastic polymer that is widely used in various industries due to its good chemical resistance, easy processing and cost-effectiveness. Despite its many advantages, polypropylene has some shortcomings that limit its wider application. For example, polypropylene has good impact strength but becomes brittle at low temperatures. Compared with polyethylene, polypropylene has limited abrasion resistance and there are challenges in processing performance, such as warping of thick-walled products, which is related to its higher shrinkage. In addition, due to its low surface energy, polypropylene is difficult to bond with adhesives and coatings, and its processing window is also narrower than that of polyethylene. Other disadvantages include poor UV resistance, flammability, and susceptibility to environmental stress cracking.

[0003] Polyethylene wax is a potential polypropylene modifier. Due to its low molecular weight, polyethylene wax has wax-like physical properties, including low viscosity, high hardness and relatively high melting point, and has good compatibility with polypropylene under certain circumstances. The processability and tensile strength of polypropylene materials modified by polyethylene wax blending can be improved, and rich functionality can be introduced into high-performance polypropylene materials. At present, the research on polyethylene wax-modified polypropylene materials in the industry is still not in-depth enough, and the poor mechanical properties and poor aging resistance of existing polyethylene wax-polypropylene composites are still problems that need to be solved urgently.

[0004] Therefore, a polyethylene wax-modified polypropylene material and a preparation method thereof are proposed. Summary of the invention

[0005] The object of the present invention is to provide a polyethylene wax modified polypropylene material and a preparation method thereof. The present invention performs in-situ polymerization grafting on polyethylene wax raw materials to obtain prefabricated polyethylene wax; melt-mixes the functional filler and the prefabricated polyethylene wax to obtain modified polyethylene wax; reacts and mixes the polypropylene resin and the modified polyethylene wax to obtain modified polypropylene; oxidatively modifies the polyethylene wax raw materials to obtain a main polyethylene wax; in-situ reacts and extrude the main polyethylene wax, a cross-linking agent and the modified polypropylene to obtain a composite polypropylene; and performs high-temperature solid-phase post-treatment on the composite polypropylene to obtain a polyethylene wax modified polypropylene material.

[0006] To achieve the above object, the present invention provides the following technical solutions: A method for preparing a polyethylene wax-modified polypropylene material comprises the following steps: Unless otherwise specified, the parts in the present invention refer to parts by mass, and the average molecular weight refers to the number average molecular weight.

[0007] The polyethylene wax raw material is subjected to in-situ polymerization grafting to obtain prefabricated polyethylene wax; Among them, the polyethylene wax raw material is high-density polyethylene degraded wax, with an average molecular weight of 8000 - 10000 Da and a density of 0.96 g / cm 3 .

[0008] The functional filler and the prefabricated polyethylene wax are melt-mixed to obtain modified polyethylene wax; Among them, the functional filler includes: ethylene-glycidyl methacrylate copolymer, trimethylolpropane, and polyethylene glycol; the average molecular weight of the ethylene-glycidyl methacrylate copolymer is 8000 - 12000 g / mol, and the copolymerization ratio of ethylene and glycidyl methacrylate is 80:20; the average molecular weight of polyethylene glycol is 500.

[0009] The polypropylene resin and the modified polyethylene wax are reaction-mixed to obtain modified polypropylene; Among them, the polypropylene resin is homopolypropylene, with an average molecular weight of 20000 - 25000 g / mol.

[0010] The polyethylene wax raw material is oxidatively modified to obtain the main polyethylene wax; The main polyethylene wax, the crosslinking agent, and the modified polypropylene are subjected to in-situ reactive extrusion to obtain composite polypropylene; Among them, the crosslinking agent includes 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane and triallyl isocyanurate; the addition molar ratio of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane and triallyl isocyanurate is 2.2:1.

[0011] The composite polypropylene is subjected to high-temperature solid-phase post-treatment to obtain a composite material product, which is a polypropylene material modified with polyethylene wax.

[0012] Preferably, the process of in-situ polymerization grafting is as follows: 100 parts of the polyethylene wax raw material and 2 - 7 parts of maleic anhydride are mixed, heated to 140 - 160 °C under anhydrous and anaerobic conditions, 0.3 - 0.6 parts of diisopropylbenzene peroxide are added, and the reaction is carried out at a stirring speed of 200 rpm for 3 hours. After the reaction is completed, the temperature is lowered to 120 °C, and vacuum treatment is carried out at an operating pressure of 0.1 atm for 30 min. Then, the obtained product is extracted with acetone for 48 hours to obtain prefabricated polyethylene wax.

[0013] Preferably, the process of melt mixing is as follows: 100 parts of prefabricated polyethylene wax, 30 - 40 parts of ethylene - glycidyl methacrylate copolymer, 2 - 4 parts of trimethylolpropane, and 1.5 - 2 parts of polyethylene glycol are mixed and fed at 120°C. After melting and stirring at 150 - 190°C for 20 min, the temperature is raised to 220°C and then fed into the main reaction zone. After mixing and reacting at a screw speed of 300 rpm for 1 hour, vacuum degassing is carried out at an operating pressure of 0.05 atm, and the modified polyethylene wax is obtained by extrusion.

[0014] Preferably, the process of reaction mixing is as follows: 90 parts of polypropylene resin and 10 - 15 parts of modified polyethylene wax are mixed and fed at 180°C. After melt blending at 190 - 210°C with a screw speed of 270 rpm for 2 hours, vacuum degassing is carried out at an operating pressure of 0.1 atm, and the modified polypropylene is obtained by extrusion.

[0015] Preferably, the process of oxidation modification is as follows: 100 parts of polyethylene wax raw material is melted at 150 - 170°C, 0.2 - 0.5 parts of benzoyl peroxide is added, dry air is introduced, and after stirring and reacting at a stirring speed of 300 rpm for 5 - 8 hours, nitrogen is introduced for purging for 2 hours, and the main body of polyethylene wax is obtained after cooling.

[0016] Preferably, the process of in - situ reactive extrusion is as follows: 80 parts of the modified polypropylene and 5 - 15 parts of the main body of polyethylene wax are mixed, fed at 160°C, melted and reacted at 210 - 220°C, 0.5 part of the cross - linker is added, and after maintaining the screw speed at 400 rpm and reacting for 2 hours, extrusion is carried out at 200°C to obtain the composite polypropylene.

[0017] Preferably, the process of high - temperature solid - phase post - treatment is as follows: Under a nitrogen atmosphere, the composite polypropylene is heated to 40 - 50°C, and vacuum treatment is carried out at an operating pressure of 0.1 atm for 30 - 60 min. Then the temperature is raised to 120 - 140°C and treated for 4 hours, and then the temperature is further raised to 155°C and treated for 16 hours. After cooling at a cooling rate of 5°C / min to 25°C, the composite material product is obtained.

[0018] A polypropylene material modified with polyethylene wax, comprising: prefabricated polyethylene wax, modified polyethylene wax, polypropylene resin, and a cross - linker.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The introduction of uniformly distributed modified polyethylene wax into the polypropylene matrix successfully co-constructed the early anchoring structure, laying the foundation for the effective combination of the main polyethylene wax introduced later. Furthermore, by introducing the main polyethylene wax with a specific structure, the synergistic effect with the early anchoring structure formed by the modified polyethylene wax greatly improved the interfacial compatibility between polyethylene wax and polypropylene, while precisely controlling the dispersion morphology of the polyethylene wax dispersed phase, improving the toughness and mechanical strength of the composite product.

[0020] 2. The main polyethylene wax and modified polypropylene matrix are effectively combined through in-situ reaction extrusion. In this process, the main polyethylene wax and the polypropylene matrix are selectively cross-linked in the interfacial area through the action of the cross-linking agent, which prevents the excessive aggregation of the polyethylene wax and forms a good co-dispersed cross-linking structure, significantly alleviating the stress concentration phenomenon of the composite product, greatly improving the compatibility of polyethylene wax and polypropylene, and enabling the composite product to maintain toughness under long-term use.

[0021] 3. Modified polyethylene wax and main polyethylene wax with different characteristics are synthesized through a specific modification process, and combined with the polypropylene matrix at different stages to achieve multi-level effective modification. Furthermore, by pre-adding functional fillers into the modified polyethylene wax, the polyethylene wax not only improves the performance of polypropylene, but also acts as a dispersing aid and interface regulator for the functional fillers, synergistically improving the performance of composite materials and expanding the application range of composite materials.

[0022] 4. Through high-temperature solid-phase post-treatment and temperature control during in-situ reaction extrusion, low molecular weight volatiles in the polymer are effectively removed, the crystal morphology of the polypropylene composite material is optimized, and the microstructure of the polyethylene wax phase and the polypropylene phase is precisely controlled. Relying on the combination of the two processes, the specific properties of different raw materials in the polypropylene composite material are effectively optimized synergistically, which significantly improves the comprehensive mechanical properties and aging resistance of the composite product, ensuring the good application value of the composite product. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The present invention is a flow chart of the preparation process of the polyethylene wax modified polypropylene material. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be clearly and completely described below through some embodiments and experimental examples. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Reference Figure 1Process flow chart as shown. The present invention provides a polypropylene material modified with polyethylene wax and its preparation method. The technical solutions are as follows:

[0026] Example 1 Mix 100 parts of the polyethylene wax raw material and 2 parts of maleic anhydride, heat to 140°C under anhydrous and anaerobic conditions, add 0.3 part of diisopropylbenzene peroxide, react at a stirring speed of 200 rpm for 3 hours, after the reaction is completed, cool to 120°C, perform vacuum treatment at an operating pressure of 0.1 atm for 30 min, and then extract the obtained product with acetone for 48 hours to obtain prefabricated polyethylene wax.

[0027] Mix 100 parts of prefabricated polyethylene wax, 30 parts of ethylene-glycidyl methacrylate copolymer, 2 parts of trimethylolpropane, and 1.5 parts of polyethylene glycol, feed at 120°C, melt and stir at 150°C for 20 min, then heat to 220°C and send to the main reaction zone, mix and react at a screw speed of 300 rpm for 1 hour, then perform vacuum exhaust at an operating pressure of 0.05 atm, and extrude to obtain modified polyethylene wax.

[0028] Mix 90 parts of polypropylene resin and 10 parts of modified polyethylene wax, feed at 180°C, melt and blend at 190°C at a screw speed of 270 rpm for 2 hours, then perform vacuum exhaust at an operating pressure of 0.1 atm, and extrude to obtain modified polypropylene.

[0029] Melt 100 parts of the polyethylene wax raw material at 150°C, add 0.2 part of benzoyl peroxide, introduce dry air and stir and react at a stirring speed of 300 rpm for 5 hours, then introduce nitrogen for purging for 2 hours, and cool to obtain the main body polyethylene wax.

[0030] Mix 80 parts of the modified polypropylene and 5 parts of the main body polyethylene wax, feed at 160°C, melt and react at 210°C, and add 0.5 part of the crosslinking agent, maintain the screw speed at 400 rpm and react for 2 hours, then extrude at 200°C to obtain composite polypropylene.

[0031] Under a nitrogen atmosphere, heat the composite polypropylene to 40°C, perform vacuum treatment at an operating pressure of 0.1 atm for 30 min, then heat to 120°C and treat for 4 hours, then continue to heat to 155°C and treat for 16 hours, and cool to 25°C at a cooling rate of 5°C / min to obtain the composite material product.

[0032] Examples 2 - 16 are different from Example 1 in operating parameters, and are the same in process sequence and raw material selection.

[0033] The specific changes in operating parameters are summarized in Tables 1 - 3.

[0034] Table 1 Variation of operating parameters in Examples 1-16 (Part 1)

[0035] Table 2 Variation of operating parameters in Examples 1-16 (Part 2)

[0036] Table 3 Variation of operating parameters in Examples 1-16 (Part 3)

[0037] Comparative Example 1 Different from Example 1, modified polyethylene wax is not added, and other process parameters are the same.

[0038] Comparative Example 2 Different from Example 1, the main polyethylene wax is not added, and other process parameters are the same.

[0039] Comparative Example 3 Different from Example 5, during the in-situ reactive extrusion process, only 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane is used as the crosslinking agent, and other process parameters are the same.

[0040] Comparative Example 4 Different from Example 5, during the in-situ reactive extrusion process, the addition amount of the crosslinking agent is increased to 2 parts, and other process parameters are the same.

[0041] Comparative Example 5 Different from Example 9, an equal amount of modified polyethylene wax is used to replace the main polyethylene wax, and other process parameters are the same.

[0042] Comparative Example 6 Different from Example 9, instead of pre-mixing the modified polyethylene wax with the polypropylene matrix, the modified polyethylene wax and the main polyethylene wax are added simultaneously during the in-situ reactive extrusion process, and other process parameters are the same.

[0043] Comparative Example 7 Different from Example 9, the functional filler is not added, and other process parameters are the same.

[0044] Comparative Example 8 Different from Example 13, during the high-temperature solid-state post-treatment process, the first and second preheating steps are not carried out, and the heating treatment is directly carried out at 155 °C, and other process parameters are the same.

[0045] Comparative Example 9 Different from Example 13, during the in-situ reactive extrusion process, the temperature of the melting reaction is changed to 180 °C, and other process parameters are the same.

[0046] Comparative Example 10 Differing from Example 13, high-temperature solid-phase post-treatment was not carried out, and other process parameters were the same.

[0047] Experimental Example 1 The composite material products prepared in Examples 1-4 and Comparative Examples 1-2 were tested for mechanical strength and toughness, and the relevant data are summarized in Table 4.

[0048] The test method for toughness was as follows: referring to the relevant test method of GBT1040.2-2022 standard, the tensile modulus (MPa) was used to represent the toughness of the material specimen.

[0049] The test method for mechanical strength was as follows: referring to the relevant test method of GBT1843-2008 standard, the cantilever beam non-notch impact test method was adopted, and the impact strength (kJ / m 2 ) was used to represent the mechanical strength of the material specimen.

[0050] Table 4 Tensile modulus and impact strength of the composite material products prepared in Examples 1-4 and Comparative Examples 1-2

[0051] As shown in the data in Table 4, the composite material products prepared in Examples 1-4 had higher impact strength with a very small difference in toughness compared to Comparative Examples 1 and 2, and had better comprehensive performance. Comparative Example 1 lacked modified polyethylene wax, which meant that an effective early anchoring structure could not be formed, resulting in poor bonding effect between the main polyethylene wax and the polypropylene matrix, reduced interfacial compatibility, and ultimately significantly lower impact strength than Example 1. Although its tensile modulus was slightly higher than that of Example 1, the obvious disadvantage in impact strength indicated that its overall mechanical properties, especially the ability to resist impact damage, were weak. Comparative Example 2 lacked the main polyethylene wax. Although there was an early anchoring structure formed by modified polyethylene wax, the lack of the synergistic effect of the main polyethylene wax could not fully exert the modification effect of polyethylene wax on polypropylene, resulting in the morphology and interfacial compatibility of the polyethylene wax dispersed phase not reaching the optimal state. Therefore, its impact strength was also much lower than that of Example 1.

[0052] In summary, the present invention significantly improved the interfacial compatibility between polyethylene wax and polypropylene by first introducing modified polyethylene wax to construct an early anchoring structure in the polypropylene matrix and then introducing the main polyethylene wax to synergistically act with the anchoring structure. This synergistic effect precisely controlled the morphology of the polyethylene wax dispersed phase, effectively improved the stress distribution of the material, avoided stress concentration, thereby improving the comprehensive performance of the composite material and ensuring higher mechanical properties with little change in toughness.

[0053] Experimental Example 2 The composite material products prepared in Examples 5-8 and Comparative Examples 3-4 were tested for aging resistance, and the relevant data are summarized in Table 5.

[0054] The test method for aging resistance was as follows: The cyclic aging experiment method was adopted. The specimen was placed at 70 °C for 4 hours, then cooled to -20 °C and held for 4 hours. The heating and cooling rates were both controlled at 1-3 °C / min. Before the aging test and after 100 cycles and 500 cycles, the tensile modulus of the specimen was tested and recorded respectively.

[0055] Table 5 Aging resistance of the composite material products prepared in Examples 5-8 and Comparative Examples 3-4

[0056] As shown in the data in Table 5, after 100 cycles and 500 cycles of cyclic aging, the tensile modulus of the composite material products in Examples 5-8 remained at a relatively high level compared to the initial value, showing good aging resistance. In Comparative Example 3, only 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane was used as the crosslinking agent, lacking the synergistic effect of triallyl isocyanurate. This led to an incomplete crosslinked structure and failed to fully form an ideal micro-crosslinked network at the phase interface, thus affecting the structural stability and toughness retention ability of the material during long-term aging, manifested as a significant decrease in the tensile modulus after 500 cycles. In Comparative Example 4, the amount of the crosslinking agent was increased to 2 parts, much higher than 0.5 part in the examples. The excessive crosslinking agent led to over-crosslinking, reducing the mobility of the polymer segments and making the material brittle, which was not conducive to the retention of toughness during long-term use. At the same time, the excessive crosslinking also caused excessive aggregation of polyethylene wax, forming an uneven crosslinked network, which also led to a significant decrease in its tensile modulus after aging.

[0057] In summary, through precise selection and control of the specific ratio and dosage of the composite crosslinking agent during the in-situ reactive extrusion process, the invention achieved effective micro-crosslinking in the phase interface region between the main polyethylene wax and the polypropylene matrix. This specific crosslinking method not only prevented the excessive aggregation of polyethylene wax but also formed a good co-dispersed crosslinked structure, thus significantly alleviating stress concentration and enhancing the compatibility between polyethylene wax and polypropylene. This precisely controlled crosslinking technical means can ensure that the composite material product still maintains high toughness under long-term cyclic aging conditions.

[0058] Experimental Example 3 The composite material products prepared in Examples 9-12 and Comparative Examples 5-7 were tested for mechanical strength and toughness, and the relevant data are summarized in Table 6.

[0059] The test method for mechanical strength and toughness refers to Experimental Example 1.

[0060] Table 6 Tensile Modulus and Impact Strength of the Composite Materials Prepared in Examples 9 - 12 and Comparative Examples 5 - 7

[0061] As shown in the data in Table 6, the composite materials in Examples 9 - 12 showed excellent performance in both tensile modulus and impact strength. In Comparative Example 5, the main polyethylene wax was completely replaced by the modified polyethylene wax, which disrupted the design of the synergistic modification of the two characteristic waxes at different stages. Although the modified polyethylene wax contains functional fillers and can bind to polypropylene, the lack of the further optimization effect of the main polyethylene wax on the interfacial compatibility and dispersion morphology in the subsequent in-situ reactive extrusion stage led to a decrease in impact strength. In Comparative Example 6, the modified polyethylene wax and the main polyethylene wax were added simultaneously during the in-situ reactive extrusion process, which made the modified polyethylene wax unable to fully react with polypropylene in advance to form the necessary early structure, and also affected the uniform dispersion of the functional fillers and the interfacial regulation effect, resulting in a significant decrease in both tensile modulus and impact strength. In Comparative Example 7, no functional fillers were added, lacking the functional fillers and their synergistic effect with the modified polyethylene wax, and the tensile modulus and impact strength of the composite material were the lowest, which highlighted the important contribution of the pre-addition of the functional fillers into the modified polyethylene wax and the pre-binding with the polypropylene matrix to the performance of the final product.

[0062] In summary, the present invention realizes multi-level synergistic modification by designing modified polyethylene waxes and main polyethylene waxes with different characteristics and introducing them into the polypropylene matrix at different stages. The modified polyethylene wax first acts with polypropylene and serves as the carrier and dispersion aid for the functional fillers, laying the foundation for the subsequent action of the main polyethylene wax and endowing the material with specific functions. The main polyethylene wax further optimizes the interface and dispersion in the subsequent stage. This multi-level and multi-component synergistic technical means effectively improves the mechanical properties of the composite material.

[0063] Experimental Example 4 The composite materials prepared in Examples 13 - 16 and Comparative Examples 8 - 10 were tested for weather resistance, mechanical strength, and toughness, and the relevant data were summarized in Table 7.

[0064] The test method for weather resistance refers to Experimental Example 2, and the test methods for mechanical strength and toughness refer to Experimental Example 1.

[0065] Table 7 Weather Resistance, Mechanical Strength, and Toughness of the Composite Materials Prepared in Examples 13 - 16 and Comparative Examples 8 - 10

[0066] As shown in the data of Table 7, the composite products of Examples 13-16 are excellent in terms of aging resistance and comprehensive mechanical properties. In Comparative Example 8, the stepwise preheating step in the high-temperature solid-phase post-treatment was omitted, and the treatment was directly carried out at 155 °C. This resulted in incomplete removal of volatiles, insufficient internal structure adjustment due to too rapid heating, and failure to achieve the optimal crystal morphology and phase microstructure. Therefore, although its aging resistance and impact strength were improved, they were still inferior to those of Example 13 with complete stepwise treatment, demonstrating the importance of stepwise preheating for optimizing the treatment effect. Comparative Example 9 changed the melting reaction temperature during the in-situ reactive extrusion process, and its comprehensive performance was inferior to that of Example 13, indirectly illustrating the importance of the coordinated matching of various parameters in the entire process chain. The high-temperature solid-phase post-treatment is an optimization based on the material formed in the previous steps. In the previous steps, improper in-situ reactive extrusion temperature limited the upper limit of performance optimization that could be achieved by the post-treatment. Comparative Example 10 did not perform the high-temperature solid-phase post-treatment at all, resulting in more low-molecular-weight volatiles remaining in the material, and the polymer crystal morphology and phase microstructure not being optimized. Therefore, its initial mechanical properties and aging resistance were the worst, directly proving the importance of the high-temperature solid-phase post-treatment step for achieving the comprehensive performance of the composite product.

[0067] In summary, the present invention, through a specific multi-stage high-temperature solid-phase post-treatment process, including preheating at a specific temperature, vacuum treatment, high-temperature treatment, duration control, and a specific cooling rate, in coordination with precise temperature control, effectively removes low-molecular-weight volatiles, optimizes the crystal morphology of the polypropylene composite, and precisely regulates the microstructure of the polyethylene wax phase and the polypropylene phase. This finely tuned post-treatment technical means significantly improves the comprehensive mechanical properties and aging resistance of the composite product, thereby obtaining a composite product with excellent performance.

[0068] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A preparation method of a polyethylene wax-modified polypropylene material, characterized in that: The preparation method is as follows: The polyethylene wax raw material is subjected to in-situ polymerization grafting to obtain prefabricated polyethylene wax; The functional filler and the prefabricated polyethylene wax are melt-mixed to obtain modified polyethylene wax; Among them, the functional filler includes: ethylene-glycidyl methacrylate copolymer, trimethylolpropane, and polyethylene glycol; The polypropylene resin and the modified polyethylene wax are subjected to reaction mixing to obtain modified polypropylene; The polyethylene wax raw material is subjected to oxidation modification to obtain the main polyethylene wax; The main polyethylene wax, the crosslinking agent, and the modified polypropylene are subjected to in-situ reactive extrusion to obtain composite polypropylene; Among them, the crosslinking agent includes 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane and triallyl isocyanurate; The composite polypropylene is subjected to high-temperature solid-phase post-treatment to obtain a composite material product, which is the polypropylene material modified with polyethylene wax.

2. The preparation method of a polypropylene material modified with polyethylene wax according to claim 1, characterized in that: The process of the in-situ polymerization grafting is as follows: by mass, 100 parts of the polyethylene wax raw material and 2-7 parts of maleic anhydride are mixed, heated to 140-160°C under anhydrous and anaerobic conditions, 0.3-0.6 parts of diisopropylbenzene peroxide are added, after the reaction is completed, vacuum treatment is carried out, and the obtained product is extracted with acetone to obtain the prefabricated polyethylene wax.

3. The preparation method of a polypropylene material modified with polyethylene wax according to claim 1, characterized in that: The process of the melt mixing is as follows: by mass, 100 parts of the prefabricated polyethylene wax, 30-40 parts of the ethylene-glycidyl methacrylate copolymer, 2-4 parts of the trimethylolpropane, and 1.5-2 parts of the polyethylene glycol are mixed, melted and stirred at 150-190°C, heated to 220°C for reaction, and after vacuum exhaust, extruded to obtain the modified polyethylene wax.

4. The preparation method of a polypropylene material modified with polyethylene wax according to claim 1, characterized in that: The process of the reaction mixing is as follows: by mass, 90 parts of the polypropylene resin and 10-15 parts of the modified polyethylene wax are mixed, melt-blended at 190-210°C, and after reaction, vacuum exhaust is carried out, and extruded to obtain the modified polypropylene.

5. The preparation method of a polypropylene material modified with polyethylene wax according to claim 1, characterized in that: The process of the oxidation modification is as follows: by mass, 100 parts of the polyethylene wax raw material is melted at 150-170°C, 0.2-0.5 parts of benzoyl peroxide are added, dry air is introduced, and the mixture is stirred and reacted at a stirring speed of 300 rpm for 5-8 hours, then nitrogen is introduced for purging for 2 hours, and after cooling, the main polyethylene wax is obtained.

6. The preparation method of a polypropylene material modified with polyethylene wax according to claim 1, characterized in that: The process of the in-situ reactive extrusion is as follows: by mass, 80 parts of the modified polypropylene and 5-15 parts of the main polyethylene wax are mixed, melted and reacted at 210-220°C, and 0.5 parts of the crosslinking agent are added, and after the reaction is completed, extruded to obtain the composite polypropylene.

7. The preparation method of a polypropylene material modified with polyethylene wax according to claim 1, characterized in that: The process of the high-temperature solid-phase post-treatment is as follows: under a nitrogen atmosphere, the composite polypropylene is heated to 40-50°C, and vacuum-treated at an operating pressure of 0.1 atm for 30-60 min, then heated to 120-140°C for treatment, and then further heated to 155°C for treatment, and after cooling, the composite material product is obtained.

8. A polyethylene wax-modified polypropylene material, characterized in that: The polypropylene material modified with polyethylene wax is prepared by the preparation method described in any one of claims 1-7; the polypropylene material modified with polyethylene wax comprises: prefabricated polyethylene wax, modified polyethylene wax, polypropylene resin and a crosslinking agent.

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