Puncture-proof polypropylene material capable of being used at low temperature as well as preparation method and application of puncture-proof polypropylene material

Abstract

The invention belongs to the technical field of polymer materials, and provides an anti-puncture polypropylene material capable of being used at low temperature as well as a preparation method and application of the anti-puncture polypropylene material. Homo-polypropylene, a core-shell structure toughening elastomer, hydroxyl-terminated polyisoprene, a nano filler and a cross-linking agent are adopted as main raw material components of the polypropylene material, and the core-shell structure toughening elastomer comprises a polysiloxane-acrylate core-shell elastomer and a polycaprolactone-styrene-acrylonitrile core-shell elastomer. The polypropylene material provided by the invention not only has excellent mechanical properties, but also can be normally used in an extremely low temperature environment of less than or equal to-30 DEG C, so that the application scene of the polypropylene material at extremely low temperature is widened.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and more specifically, to a low-temperature usable, puncture-resistant polypropylene material, its preparation method, and its applications. Background Technology

[0002] Polypropylene (PP) materials are widely used in automotive parts, packaging, construction, and protective equipment due to their lightweight, chemical resistance, and low cost. However, traditional PP is prone to embrittlement in extreme low-temperature environments (such as ≤-30℃), resulting in a significant decrease in impact resistance and poor resistance to punctures by sharp objects. This limits its application in extremely cold regions (such as automotive dashboards, and special protective equipment like puncture-resistant vests and industrial protective gear). Currently, there is a lack of polypropylene materials on the market that combine low-temperature toughness and puncture resistance, and existing modification technologies (such as adding rubber or inorganic fillers) often sacrifice the material's rigidity or processing properties.

[0003] Therefore, there is an urgent need to develop a polypropylene material that can still be used under extreme low temperature conditions (such as ≤-30℃) while maintaining high puncture resistance and high toughness. Summary of the Invention

[0004] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a low-temperature usable, puncture-resistant polypropylene material, its preparation method, and its applications. The polypropylene material provided by this invention can still be used under extreme low-temperature conditions (e.g., ≤-30℃), maintaining high puncture resistance and high toughness (e.g., at -30℃, the notched impact strength of a cantilever beam can reach 5.8-7 kJ / m). 2 Its puncture resistance can reach 98-115N.

[0005] A first aspect of the present invention provides a puncture-resistant polypropylene material that can be used at low temperatures.

[0006] Specifically, a low-temperature usable, puncture-resistant polypropylene material comprises the following raw material components: Homopolymer polypropylene, Core-shell toughened elastomers Hydroxyl-terminated polyisoprene Nanofillers, Crosslinking agent; The core-shell toughened elastomers include polysiloxane-acrylate core-shell elastomers and polycaprolactone-styrene-acrylonitrile core-shell elastomers.

[0007] This invention uses homopolymer polypropylene as the matrix resin and two different polysiloxane-acrylate core-shell elastomers and polycaprolactone (PCL)-styrene-acrylonitrile (SAN) core-shell elastomers as toughening agents. It also adds hydroxyl-terminated polyisoprene, which retains excellent elastic deformation capacity even at extreme low temperatures and can synergistically work with the two elastomers to construct a dense "flexible toughening network," inhibiting low-temperature brittleness and improving the puncture resistance of polypropylene materials. Its hydroxyl groups also enhance compatibility with other components. Nanofillers act as a rigid supporting framework and inhibit crack initiation and propagation, further improving puncture resistance. Therefore, this invention achieves a synergistic improvement in low-temperature puncture resistance and toughness, expanding the application scenarios of polypropylene materials at extreme low temperatures.

[0008] Preferably, the core-shell toughened elastomer comprises a polysiloxane-acrylate core-shell elastomer and a polycaprolactone-styrene-acrylonitrile core-shell elastomer with a mass ratio of 1-3:1.

[0009] More preferably, the core-shell toughened elastomer comprises a polysiloxane-acrylate core-shell elastomer and a polycaprolactone-styrene-acrylonitrile core-shell elastomer with a mass ratio of 1-2:1.

[0010] Preferably, the polysiloxane-acrylate core-shell elastomer is prepared by a method comprising the following steps: (1) Water, anionic emulsifier, octamethylcyclotetrasiloxane, and silane coupling agent are mixed and reacted to obtain seed emulsion; (2) Mix water, anionic emulsifier, octamethylcyclotetrasiloxane, silane coupling agent and hexamethyldisiloxane, and then add them to the seed emulsion. After the reaction, a polysiloxane core emulsion is obtained. (3) Adjust the pH of the polysiloxane core emulsion to alkaline, introduce a protective gas, add acrylate monomer, crosslinking agent and regulator, swell, then add an initiator and react for 2-3 hours; then demulsify, centrifuge, dry, and obtain the polysiloxane-acrylate core-shell elastomer.

[0011] Preferably, the anionic emulsifier is dodecylbenzenesulfonic acid (DBSA) and / or sodium dodecyl sulfate (SDS).

[0012] Preferably, the silane coupling agent is γ-methacryloxypropyltrimethoxysilane (KH-570) and / or γ-methacryloxypropyltriethoxysilane.

[0013] Preferably, the protective gas is nitrogen.

[0014] Preferably, the crosslinking agent is ethylene glycol dimethacrylate (EGDMA) and / or triethylene glycol dimethacrylate.

[0015] Preferably, the regulator is dodecyl mercaptan (TDM) and / or n-octyl mercaptan.

[0016] Preferably, the anionic emulsifier accounts for 1-2 wt% of the total mass of water in the system.

[0017] Preferably, the initiator is potassium persulfate and / or ammonium persulfate.

[0018] Preferably, the initiator is 0.2-0.5 wt% of the total monomer mass.

[0019] Preferably, the mass ratio of polysiloxane to acrylate monomer in the polysiloxane core emulsion is 5:(4-6).

[0020] Preferably, in step (3), the pH value of the polysiloxane core emulsion is adjusted to 8-9.

[0021] Preferably, in step (3), the acrylate monomer is butyl acrylate (BA) and / or methyl methacrylate (MMA).

[0022] More preferably, in step (3), the acrylate monomers are butyl acrylate (BA) and methyl methacrylate (MMA).

[0023] More preferably, in step (3), the acrylate monomers are butyl acrylate (BA) and methyl methacrylate (MMA) in a mass ratio of 3:(3-5).

[0024] Preferably, in step (3), calcium chloride solution is added to break the emulsion.

[0025] Preferably, in step (3), after drying, the product is further extracted using methanol and acetone as extraction solvents and a Soxhlet extractor to obtain the purified polysiloxane-acrylate core-shell elastomer.

[0026] Preferably, the polycaprolactone-styrene-acrylonitrile core-shell elastomer is prepared by a method comprising the following steps: (1) The ε-caprolactone monomer, the first initiator, the molecular weight regulator and the solvent are mixed and polymerized. After removing the solvent, PCL microspheres are obtained. (2) The PCL microspheres, water, and emulsifier are mixed, and then styrene, acrylonitrile, glycidyl methacrylate and a second initiator are added. After the reaction, the mixture is dried to obtain the polycaprolactone-styrene-acrylonitrile core-shell elastomer.

[0027] Preferably, in step (1), the temperature of the polymerization reaction is 100-120°C, and / or the time of the polymerization reaction is 3-5 hours.

[0028] Preferably, in step (2), the reaction temperature is 70-90°C, and / or the reaction time is 3-15 h.

[0029] Preferably, the first initiator is stannous octoate and / or bismuth isooctanoate.

[0030] Preferably, the second initiator is azobisisobutyronitrile and / or dimethyl azobisisobutyrate.

[0031] Preferably, the molecular weight regulator is 1,4-butanediol and / or pentaerythritol.

[0032] Preferably, the solvent is toluene and / or cyclohexane.

[0033] Preferably, the emulsifier is sodium dodecyl sulfate (SDS) and / or ammonium dodecyl sulfate.

[0034] Preferably, the nanofiller includes modified nano-calcium carbonate (such as nano-calcium carbonate with surface modified by stearic acid) and / or modified nano-silica (such as nano-silica modified by silane coupling agent).

[0035] Preferably, the crosslinking agent comprises dicumyl peroxide (DCP) and / or trimethylolpropane trimethacrylate (TMPTMA).

[0036] Preferably, the polypropylene material comprises the following raw material components in parts by weight: 100 parts of homopolymer polypropylene 15-25 parts of core-shell toughened elastomer 1-5 parts of hydroxyl-terminated polyisoprene 3-10 parts of nanofiller Crosslinking agent 0.1-0.5 parts.

[0037] More preferably, the polypropylene material comprises the following raw material components in parts by weight: 100 parts of homopolymer polypropylene 15-22 parts of core-shell toughened elastomer 3-5 parts of hydroxyl-terminated polyisoprene 5-8 parts of nanofiller Crosslinking agent 0.3-0.5 parts.

[0038] Preferably, the raw material components further include auxiliary modifiers.

[0039] Preferably, the auxiliary modifier includes a compatibilizer and / or an antioxidant.

[0040] Preferably, the raw material components of the polypropylene material include 3-5 parts compatibilizer and / or 0.1-0.3 parts antioxidant, based on parts by weight.

[0041] Preferably, the compatibilizer includes at least one of ethylene-vinyl acetate copolymer (EVA, for example, EVA with a VA content of 28%), ethylene-octene copolymer (POE), and maleic anhydride-grafted polypropylene.

[0042] Preferably, the antioxidant includes antioxidant 1010 and / or antioxidant 168.

[0043] A second aspect of the present invention provides a method for preparing a puncture-resistant polypropylene material that can be used at low temperatures.

[0044] A method for preparing a low-temperature usable, puncture-resistant polypropylene material includes the following steps: (1) Homopolymer polypropylene and core-shell toughened elastomer are mixed to obtain the first premix; (2) The nanofiller and hydroxyl-terminated polyisoprene are mixed to obtain a second premix; (3) The first premix and the second premix are mixed, and then a crosslinking agent is added. The mixture is melt-extruded, granulated, and injection molded to obtain the polypropylene material.

[0045] Preferably, in step (1), the temperature at which the homopolymer polypropylene and the core-shell toughened elastomer are mixed is 40-50°C, and / or the mixing time is 1-10 min.

[0046] Preferably, in step (2), the nanofiller and hydroxyl-terminated polyisoprene are mixed by first mixing at 50-70°C for 5-15 min, and then heating to 90-110°C and mixing for 10-20 min.

[0047] Preferably, in step (2), the auxiliary modifier is mixed together with the nanofiller and the hydroxyl-terminated polyisoprene.

[0048] Preferably, in step (3), the first premix and the second premix are added and mixed from different feed ports of the screw extruder.

[0049] More preferably, in step (3), the first premix is ​​added from the main feed port of the screw extruder, and the second premix is ​​added from the side feed port of the screw extruder.

[0050] A third aspect of the present invention provides an application of a puncture-resistant polypropylene material that can be used at low temperatures.

[0051] Application of a low-temperature usable, puncture-resistant polypropylene material in the preparation of low-temperature protective materials, packaging materials, building materials, and automotive parts.

[0052] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention uses homopolymer polypropylene, core-shell toughened elastomer, hydroxyl-terminated polyisoprene, nanofillers, and crosslinking agents as the main raw material components of a low-temperature usable, puncture-resistant polypropylene material. Homopolymer polypropylene is used as the matrix resin, and two different core-shell toughened elastomers—polysiloxane-acrylate core-shell elastomer and polycaprolactone-styrene-acrylonitrile core-shell elastomer—are used as toughening agents. The hydroxyl-terminated polyisoprene synergistically works with the two elastomers to construct a dense, flexible toughening network, inhibiting low-temperature brittleness. This invention improves puncture resistance, and its hydroxyl groups also enhance compatibility with other components. Simultaneously, the nanofiller acts as a rigid framework, resisting cracks and preventing punctures. Therefore, the polypropylene material provided by this invention not only possesses excellent mechanical properties (such as tensile strength reaching 28.8-29.6 MPa and flexural modulus reaching 1350-1450 MPa), but also remains usable even in extreme low-temperature environments ≤-30℃ (e.g., cantilever beam notched impact strength reaches 5.8-7 kJ / m at -30℃). 2 With a puncture resistance of 98-115N, polypropylene materials have been broadened to be applicable in extreme low-temperature environments. Detailed Implementation

[0053] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0054] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0055] The sources of the main raw materials used in the embodiments or comparative examples of this invention are as follows: Homopolymer polypropylene: Produced by Sinopec Beijing Yanshan Petrochemical Co., Ltd.; Model: PPH-T03.

[0056] Polysiloxane-acrylate core-shell elastomer: First, deionized water and dodecylbenzenesulfonic acid (DBSA) were added to a flask and mixed thoroughly. Then, octamethylcyclotetrasiloxane (D4) and KH-570 were mixed thoroughly and added dropwise to the flask. The reaction was carried out to obtain a seed emulsion. Deionized water, dodecylbenzenesulfonic acid (DBSA), octamethylcyclotetrasiloxane (D4), KH-570, and hexamethyldisiloxane (MM) were mixed at room temperature and homogenized. Then, the mixture was slowly added dropwise to the above seed emulsion. After the addition was complete, the reaction was carried out for 3 hours. After cooling to room temperature, a polysiloxane core emulsion was obtained. The pH of the polysiloxane core emulsion was adjusted to 8-9 using 3.0 wt% NaOH solution, and nitrogen gas was introduced for about 15-30 minutes. A mixture of butyl acrylate (BA), ethylene glycol dimethacrylate (EGDMA), and dodecyl mercaptan (TDM) was added to the emulsion. After the emulsion swelled, a pre-prepared initiator buffer solution (a mixture of potassium persulfate, trisodium phosphate, and water) was slowly added dropwise, and the reaction was allowed to proceed for 2.5 hours. Methyl methacrylate (MMA) was added dropwise, and after the MMA swelled, a pre-prepared initiator buffer solution (a mixture of potassium persulfate, trisodium phosphate, and water) was slowly added dropwise, and the reaction was allowed to proceed for 2.5 hours. A 5.0 wt% calcium chloride solution was added to break the emulsion. The emulsion was washed with water and centrifuged, and then dried in a vacuum drying oven at 80°C for 24 hours to obtain a white powder. Using methanol and acetone as extraction solvents, the white powder was extracted using a Soxhlet extractor to remove unreacted monomers and homopolymers, yielding purified polysiloxane-acrylate core-shell elastomer (average particle size approximately 194 nm). The mass ratio of polysiloxane to acrylate monomers was 5:5, the amount of potassium persulfate initiator was 0.36 wt% of the total monomer mass, the amount of anionic emulsifier DBSA was 1.4 wt% of the total water content, and the mass ratio of BA to MMA monomers in the acrylate monomers was 3:4.

[0057] Polycaprolactone-styrene-acrylonitrile core-shell elastomer: prepared in two steps with the following raw materials: Step 1 (PCL core layer preparation): 60g ε-caprolactone monomer, 0.2g stannous octoate initiator, 0.8g 1,4-butanediol molecular weight regulator, and 100g toluene; Step 2 (SAN shell coating): PCL microspheres prepared in Step 1 (dry weight 60g), 24g styrene, 12g acrylonitrile, 4g glycidyl methacrylate, 0.6g azobisisobutyronitrile initiator, 250g deionized water, and 2g sodium dodecyl sulfate (SDS) emulsifier. Step 1: Ring-opening polymerization to prepare PCL microspheres: ε-caprolactone, stannous octoate, 1,4-butanediol, and toluene were added to a reactor, heated to 110℃ under nitrogen protection, and reacted for 4 hours. Toluene was removed by vacuum distillation to obtain PCL microspheres. Step 2: In-situ polymerization to coat the shell: PCL microspheres, deionized water, and SDS were added to a reactor and ultrasonically dispersed for 30 minutes. The temperature was raised to 80℃. A mixture of styrene, acrylonitrile, glycidyl methacrylate monomers, and an azobisisobutyronitrile solution (azobisisobutyronitrile dissolved in 30g acetone) was slowly added dropwise to the reactor over 2 hours. After the addition was complete, the reaction was maintained at the temperature for 8 hours. After the reaction was completed, the mixture was filtered, and the precipitate was washed three times alternately with deionized water and acetone. The precipitate was then dried in a vacuum drying oven at 85℃ for 10 hours to obtain the product, polycaprolactone-styrene-acrylonitrile core-shell elastomer (average particle size 0.6-1.2μm).

[0058] Hydroxyl-terminated polyisoprene: A dry polymerization flask was degassed, and 5 mL of isoprene and 1 mL of sec-butyllithium were added. The mixture was reacted in a water bath at 30°C for 1 hour. Then, 2 mL of propylene oxide was added to the polymerization flask, and the reaction was continued at 30°C for 4 hours. Finally, degassed methanol was added to terminate the reaction. The precipitate was poured into isopropanol, yielding a white, viscous substance, which is the hydroxyl-terminated polyisoprene.

[0059] Nanofiller: Modified nano calcium carbonate, produced by Shanghai Huaming Gaona Rare Earth New Materials Co., Ltd.; Model: HM-CaCO3-50 (particle size 50nm, surface modified with stearic acid, activation degree ≥95%).

[0060] Crosslinking agent: dicumyl peroxide (DCP), manufactured by AkzoNobel; model: DCP-40C.

[0061] Compatibilizer: Ethylene-vinyl acetate copolymer (EVA), manufactured by ExxonMobil; Model: EVANE TM LD 767.00 (VA content 28%, melt index 2.5 g / 10 min).

[0062] Antioxidants: Antioxidant 1010 and Antioxidant 168 in a 1:1 mass ratio. Antioxidant 1010: Manufactured by BASF; Model: Irganox® 1010. Antioxidant 168: Manufactured by BASF; Model: Irgafos® 168.

[0063] Example 1 A polypropylene material comprising raw material components as shown in Table 1 by weight.

[0064] The preparation method of the above-mentioned polypropylene material includes the following steps: (1) Homopolymer polypropylene and core-shell toughened elastomer were added to a high-speed mixer and mixed at 45°C for 5 min to obtain the first premix. (2) Add nanofiller, hydroxyl-terminated polyisoprene, compatibilizer and antioxidant to a high-speed mixer and mix at 60°C for 10 min. Then raise the temperature to 100°C and stir for 15 min to obtain the second premix. (3) A twin-screw extruder was used, with the following temperature gradients: Zone 1 160℃, Zone 2 170℃, Zone 3 180℃, Zone 4 175℃, and die head 185℃. The screw speed was 300r / min. The first premix was added through the main feed port, and the second premix was added through the side feed port. Then, a crosslinking agent was added, and the melt was extruded. After being cooled to room temperature by water cooling, the melt was granulated by a pelletizer, and finally, the polypropylene material was obtained by injection molding.

[0065] Examples 2-5 Examples 2-5 provide polypropylene materials, which differ from Example 1 in that the raw material components and their amounts are different, as shown in Table 1. The preparation methods are the same as in Example 1.

[0066] Comparative Examples 1-3 Comparative Examples 1-3 provide polypropylene materials, which differ from Example 1 in that the raw material components are different, as shown in Table 1. The preparation method is the same as in Example 1.

[0067] Table 1. Raw material components and their amounts (parts by weight) for each embodiment and comparative example.

[0068] Product effectiveness test 1. Testing Method The polypropylene materials of each embodiment and comparative example were subjected to the following tests at a test environment of -30°C: (1) Impact strength of cantilever beam with notch (kJ / m) 2GB / T 1843-2008 "Determination of Impact Strength of Plastic Cantilever Beams"; The test sample size is 80mm×10mm×4mm. After the sample is placed at a constant temperature of -30℃ for 2 hours, it is tested using a cantilever beam impact testing machine. The energy absorbed when the sample breaks is recorded, and the impact strength is calculated. The higher the value, the stronger the material's ability to resist impact damage at notched parts at low temperatures, and the lower the risk of brittle fracture.

[0069] (2) Puncture resistance (N): GB / T 10004-2008 "Dry lamination and extrusion lamination of plastic composite films and bags for packaging"; The test sample diameter is 100mm. The sample is fixed on the test fixture and placed at a constant temperature of -30℃ for 2 hours. A steel needle with a diameter of 1mm and a spherical tip radius of 0.5mm is selected, and the puncture speed is set to 50mm / min until the sample is punctured. The maximum puncture force is recorded as the puncture resistance. The larger the value, the stronger the material's ability to resist puncture by sharp objects at low temperatures, and the more difficult it is to be penetrated.

[0070] (3) Tensile strength (MPa): GB / T 1040.1-2025 "Determination of tensile properties of plastics - Part 1: General rules"; The test sample is a type 1A dumbbell-shaped sample (total length 150mm, effective gauge length 50mm, gauge length width 10mm, thickness 4mm). After the sample is placed at a constant temperature of -30℃ for 2h, it is tested using a universal testing machine. The tensile speed is set to 50mm / min. The maximum tensile stress when the sample breaks is recorded as the tensile strength.

[0071] (4) Flexural modulus (MPa): GB / T 9341-2008 "Determination of Flexural Properties of Plastics"; The test sample size is 80mm×10mm×4mm. The sample is placed at a constant temperature of -30℃ for 2 hours and then tested using a universal testing machine.

[0072] 2. Test Results Table 2 Performance test results of polypropylene materials in each example and comparative example

[0073] As shown in the table above, the polypropylene materials prepared in Examples 1-5 of this invention have a tensile strength of 28.8-29.6 MPa and a flexural modulus of 1350-1450 MPa, exhibiting excellent mechanical properties. Moreover, at a low temperature of -30℃, the notched impact strength of the cantilever beam can reach 5.8-7 kJ / m. 2 Its puncture resistance can reach 98-115N, indicating that it has high toughness and puncture resistance at extreme low temperatures of -30℃.

[0074] As can be seen from the comparison of Examples 1-3, when different ratios of polysiloxane-acrylate core-shell elastomer and polycaprolactone-styrene-acrylonitrile core-shell elastomer are used, Example 3 (the mass ratio of polysiloxane-acrylate core-shell elastomer to polycaprolactone-styrene-acrylonitrile core-shell elastomer is 8:7) exhibits the best toughness and puncture resistance at low temperatures.

[0075] A comparison of Examples 1, 4, and 5 shows that when using different amounts of terminal hydroxyl polyisoprene, Example 4 exhibits the best toughness and puncture resistance at low temperatures.

[0076] Compared with Example 1, Comparative Example 1 did not add polysiloxane-acrylate core-shell elastomer, Comparative Example 2 did not add polycaprolactone-styrene-acrylonitrile core-shell elastomer, and Comparative Example 3 did not add hydroxyl-terminated polyisoprene, all of which resulted in a significant decrease in toughness and puncture resistance at low temperatures.

Claims

1. A polypropylene material, characterized in that, It includes the following raw material components: Homopolymer polypropylene, Core-shell toughened elastomers Hydroxyl-terminated polyisoprene Nanofillers, Crosslinking agent; The core-shell toughened elastomers include polysiloxane-acrylate core-shell elastomers and polycaprolactone-styrene-acrylonitrile core-shell elastomers.

2. The polypropylene material according to claim 1, characterized in that, The core-shell toughened elastomer includes polysiloxane-acrylate core-shell elastomer and polycaprolactone-styrene-acrylonitrile core-shell elastomer with a mass ratio of 1-3:

1.

3. The polypropylene material according to claim 1, characterized in that, The nanofiller includes modified nano-calcium carbonate and / or modified nano-silica.

4. The polypropylene material according to claim 1, characterized in that, The crosslinking agent includes dicumyl peroxide and / or trimethylolpropane trimethacrylate.

5. The polypropylene material according to claim 1, characterized in that, The raw material components of the polypropylene material also include auxiliary modifiers, which include compatibilizers and / or antioxidants.

6. The polypropylene material according to claim 5, characterized in that, The compatibilizer includes at least one of ethylene-vinyl acetate copolymer, ethylene-octene copolymer, and maleic anhydride-grafted polypropylene.

7. The polypropylene material according to claim 1, characterized in that, The polypropylene material comprises the following raw material components in parts by weight: 100 parts of homopolymer polypropylene 15-25 parts of core-shell toughened elastomer 1-5 parts of hydroxyl-terminated polyisoprene 5-10 parts of nanofiller Crosslinking agent 0.1-0.5 parts.

8. A method for preparing the polypropylene material according to any one of claims 1-7, characterized in that, Includes the following steps: (1) Homopolymer polypropylene and core-shell toughened elastomer are mixed to obtain the first premix; (2) The nanofiller and hydroxyl-terminated polyisoprene are mixed to obtain a second premix; (3) The first premix and the second premix are mixed, and then a crosslinking agent is added. The mixture is melt-extruded, granulated, and injection molded to obtain the polypropylene material.

9. The preparation method according to claim 8, characterized in that, In step (2), the nanofiller and hydroxyl-terminated polyisoprene are mixed by first mixing at 50-70℃ for 5-15 min, and then heating to 90-110℃ and mixing for 10-20 min to obtain the second premix.

10. The use of the polypropylene material according to any one of claims 1-7 in the preparation of low-temperature protective materials, packaging materials, building materials, and automotive parts.

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