Lightweight low-temperature-impact-resistant bumper material and preparation method thereof

Abstract

The invention relates to the field of high polymer materials for automobiles, and particularly discloses a light-weight low-temperature-impact-resistant bumper material and a preparation method thereof. The light-weight low-temperature-impact-resistant bumper material is prepared from the following raw materials in parts by weight: 45 to 70 parts of silicon dioxide toughened polypropylene, 10 to 20 parts of polyamide 6, 10 to 35 parts of elastomer, 30 to 45 parts of graphene modified carbon fiber, 5 to 10 parts of inorganic filler, 0.5 to 2 parts of antioxidant and 5 to 10 parts of compatilizer. The light-weight low-temperature-impact-resistant bumper material not only has the advantage of light weight, but also has rigidity and toughness, and the low-temperature-resistant performance of a bumper is improved.

Description

TECHNICAL FIELD

[0001] The application relates to the field of high polymer materials for automobiles, in particular to a light-weight low-temperature impact-resistant bumper material and a preparation method thereof. BACKGROUND

[0002] The automobile bumper can absorb and buffer the impact force from the outside, protect the vehicle body and improve the aerodynamic characteristics of the vehicle, and belongs to a safety part. When the bumper is impacted, the impact energy is absorbed, and plastic deformation is generated at the same time, so as to reduce the energy transmission. At present, metal materials such as steel are commonly used in bumpers, which have strong load capacity and good impact resistance, but the density of steel is large, which is not conducive to light weight. However, the light weight of the automobile is of great significance to improve the power performance and fuel economy of the automobile, so the related technology uses polypropylene to replace steel to reduce the density of the bumper and realize light weight.

[0003] In the prior art, the Chinese patent application file with the application number CN202510049619X discloses a light-weight automobile bumper and a preparation method thereof, which is prepared from the following raw materials and weight parts: polypropylene resin 45-70 parts; polyhexamethylene adipamide 5-20 parts; carbon fiber 25-40 parts; graphene 0.05-0.1 parts; antioxidant 0.5-2 parts; pigment 0.2-2 parts; and compatibilizer 1-5 parts. The performance of polypropylene and carbon fiber is improved by polyhexamethylene adipamide and graphene, and a light-weight and high-strength automobile bumper is prepared, but the rigidity is strong and the toughness is insufficient, so that brittle fracture easily occurs at low temperature.

[0004] Therefore, there is a need for a bumper material with light weight characteristics and high impact resistance at low temperature. This bumper is expected to effectively improve the low-temperature impact resistance on the basis of maintaining rigidity and light weight, so as to ensure that the bumper can exhibit reliable durability and safety under various environmental conditions. SUMMARY

[0005] In order to improve the low-temperature impact resistance of the bumper, the application provides a light-weight low-temperature impact-resistant bumper material and a preparation method thereof.

[0006] In the first aspect, the application provides a light-weight low-temperature impact-resistant bumper material, which adopts the following technical scheme: a light-weight low-temperature impact-resistant bumper material, comprising the following raw materials in weight parts: silica toughened polypropylene 45-70 parts, polyamide 6 10-20 parts, elastomer 10-35 parts, graphene modified carbon fiber 30-45 parts, inorganic filler 5-10 parts, antioxidant 0.5-2 parts, and compatibilizer 5-10 parts.

[0007] By adopting the above technical scheme, the silica is added in the polypropylene to prepare the silica toughened polypropylene, thereby improving the impact strength of the polypropylene, and enhancing the low-temperature impact resistance of the bumper material; the silica toughened polypropylene has a large amount of beta crystals, the stacking mode of the beta crystals has more voids, the density of the silica toughened polypropylene is obviously reduced, the lightweight of the system is realized; the elastomer has good toughness, and the low-temperature resistance of the system is further improved; the graphene modified carbon fiber has the advantages of excellent toughness and small anisotropy, and cooperates with the silica toughened polypropylene and the elastomer to improve the toughness, lightweight and low-temperature resistance of the system as a whole.

[0008] Optionally, the preparation method of the silica toughened polypropylene comprises the following steps: (1) mixing, melting and granulating polypropylene, dicyclohexyl terephthalamide and maleic anhydride grafted polypropylene according to a mass ratio of 96-98:0.4-1:1-3 to prepare masterbatch; (2) mixing, melting and granulating the masterbatch, nano-silica and mineral oil swelling treated ultra-high molecular weight polyethylene according to a mass ratio of 90-95:1-5:1-5 to prepare the silica toughened polypropylene.

[0009] By adopting the above technical scheme, the dicyclohexyl terephthalamide has heterogeneous nucleation effect, can induce the polypropylene to generate a large amount of beta crystals, and make the polypropylene have higher impact strength, exhibit higher toughness and ductility; the hydrogen bond exists between the nano-silica and the dicyclohexyl terephthalamide, improves the dispersion of the nano-silica in the polypropylene, and the synergistic effect of the dicyclohexyl terephthalamide and the nano-silica can comprehensively improve the tensile and impact properties of the polypropylene, and has synergistic toughening effect; the melt viscosity of the ultra-high molecular weight polyethylene is high, it is difficult to blend with the polypropylene, and it is easy to form agglomeration, but after the swelling treatment of the mineral oil, the entanglement density of the ultra-high molecular weight polyethylene is reduced, the compatibility of the polypropylene is improved, the phase separation of the two is reduced, the dispersed ultra-high molecular weight polyethylene forms a micro-fiber structure when stressed, induces the polyethylene to generate silver lines and shear yield, absorbs impact energy, hinders crack propagation, delays material fracture, and enhances the toughness of the polypropylene, and the glass transition temperature of the ultra-high molecular weight polyethylene is low, the flexible segment can still maintain plastic deformation ability at low temperature, and compensates the low-temperature brittleness of the polypropylene.

[0010] Optionally, the raw material of the graphene modified carbon fiber comprises polypropylene, graphene and carbon fiber, and the mass ratio of the polypropylene, the graphene and the carbon fiber is 0.5-1.5:0.5-1.5:7-8.

[0011] Optionally, the preparation method of the graphene modified carbon fiber comprises the following steps: The carbon fiber is soaked in acetone for 0.5-1 hour, then ultrasonically cleaned and dried with ethanol, and then added to a concentrated nitric acid solution with a concentration of 60-70% for acid immersion treatment for 0.5-1.5 hours, followed by water washing and drying to obtain pretreated carbon fiber. Graphene and sodium dodecylbenzenesulfonate were added to water, stirred, and ultrasonically treated to obtain a graphene suspension. Polypropylene powder was added while stirring the graphene suspension, and then dried to obtain a polypropylene / graphene composite powder. Polypropylene / graphene composite powder was dispersed in an ethanol solution, then pretreated carbon fibers were added, mixed evenly, and dried to obtain graphene-modified carbon fibers.

[0012] By adopting the above technical solution, acetone is used to treat the grease or contaminants on the carbon fiber surface, ethanol cleaning further removes residual acetone, and nitric acid solution immersion increases the etching grooves on the carbon fiber surface and forms acidic groups; sodium dodecylbenzene sulfonate makes graphene uniformly dispersed in the polypropylene particle suspension, and after drying, the graphene is adsorbed on the surface of the polypropylene particles, reducing graphene agglomeration; during the mixing process of polypropylene / graphene composite powder and treated carbon fiber, the etching grooves on the carbon fiber surface adsorb the polypropylene / graphene composite powder, and the acidic groups can form a stable interface bond with polypropylene through chemical bonds or strong interactions. Therefore, the polypropylene / graphene composite powder is bonded to the carbon fiber surface after acid treatment, and the uniformly attached polypropylene / graphene composite powder covers the carbon fiber surface, forming a continuous interface layer, which enhances the rigidity and toughness of the carbon fiber and reduces the anisotropy of the carbon fiber. Reducing anisotropy can avoid stress concentration cracking caused by poor radial bonding.

[0013] Optionally, the elastomer comprises metallocene polyethylene elastomer and EPDM in a mass ratio of 1:0.5-1.

[0014] By employing the above technical solution, metallocene polyethylene elastomer (mPE) and EPDM synergistically toughen and modify polypropylene, thereby improving the impact strength and toughness of polypropylene. mPE and EPDM are dispersed in the continuous phase of polypropylene in particulate form. When the material is subjected to external impact, the mPE and EPDM particles become stress concentration points, deforming under the action of external force and generating numerous crazes and shear bands, thus consuming energy. Simultaneously, the interaction between the crazes, shear bands, and elastomer particles can prevent the crazes and shear bands from further transforming into destructive cracks, significantly improving the material's toughness.

[0015] Optionally, the mass ratio of the silica-toughened polypropylene to the elastomer is 5:2.

[0016] By adopting the above technical solution, at this optimal ratio, the compatibilizer can fully act on the two-phase interface between silica-toughened polypropylene and elastomer, forming good interfacial adhesion, ensuring that stress can be effectively transferred from silica-toughened polypropylene to the dispersed phase particles of mPE and EPDM, and the toughness of the composite material reaches the optimal level.

[0017] Optionally, the inorganic filler is selected from at least one of talc, calcium carbonate, mica, and kaolin.

[0018] By adopting the above technical solution, inorganic fillers can increase the rigidity of the system and have a certain lubricating effect. This avoids problems such as blockage of the discharge pipe or uneven discharge caused by excessive polymer viscosity during bumper manufacturing.

[0019] Optionally, the compatibilizer is maleic anhydride-grafted polypropylene.

[0020] By adopting the above technical solution, the use of compatibilizer further increases the compatibility between silica-toughened polypropylene, polyamide 6, elastomer and graphene-modified carbon fiber, avoiding interfacial debonding, brittle fracture and sudden drop in impact strength at low temperature, thereby improving low temperature resistance.

[0021] Optionally, the antioxidant is any one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine, and tris(2,4-di-tert-butylphenyl)phosphite.

[0022] By adopting the above technical solution, the antioxidant can mitigate the high-temperature oxidation that may occur during the high-temperature processing of the system, thus preventing the bumper from suffering surface quality deterioration, such as yellowing and discoloration.

[0023] Secondly, this application provides a method for preparing a lightweight, low-temperature impact-resistant bumper material, employing the following technical solution: A method for preparing a lightweight, low-temperature impact-resistant bumper material includes the following steps: The silica-toughened polypropylene, polyamide 6, graphene-modified carbon fiber, elastomer, antioxidant, compatibilizer and inorganic filler are mixed evenly, melt-extruded at 215℃-255℃, cooled, pelletized and dried to obtain the bumper material.

[0024] By adopting the above technical solution, the raw materials can be mixed evenly, and the operation is simple and easy to process, making it suitable for continuous production.

[0025] In summary, this application has the following beneficial effects: 1. This application preferably uses silica-toughened polypropylene as the base material. The toughness of polypropylene is increased by silica, and the addition of elastomers further improves the impact toughness of the composite material. Graphene-modified carbon fiber can enhance the rigidity and impact toughness of polypropylene in the composite material. Combined with polyamide 6 and elastomers, it further improves the low-temperature performance of the system.

[0026] 2. This application utilizes polypropylene as a carrier and sodium dodecylbenzenesulfonate as a dispersant to reduce graphene agglomeration, allowing graphene to be uniformly attached to polypropylene powder. Then, the polypropylene / graphene composite powder is adsorbed by the etching grooves on the carbon fiber surface. The polypropylene / graphene composite powder fills the carbon fiber, reducing the anisotropy of the carbon fiber and increasing its rigidity. At the same time, it improves the compatibility between the carbon fiber and the silica-toughened polypropylene matrix, thereby enabling the graphene-modified carbon fiber to form a multi-level reinforcing network in the polypropylene matrix, achieving improved high strength, high toughness, and low-temperature impact resistance.

[0027] 3. This application preferably uses metallocene polyethylene elastomer and EPDM compound as elastomer. The two are dispersed in particulate form in the continuous polypropylene phase, thereby reducing stress concentration and improving low-temperature crack resistance. Detailed Implementation

[0028] The following embodiments provide a further detailed description of this application.

[0029] Example of preparation of silica-toughened polypropylene In Examples 1-6 of the preparation of silica-toughened polypropylene, the polypropylene was isotactic polypropylene with an isotacticity of 95% and a melt index of 2.5 g / 10 min, purchased from Yangzi Petrochemical Company, model F401; the ultra-high molecular weight polyethylene had a molecular weight ≥ 5 million, purchased from Ticona Inc., USA, model GUR4120; the nano silica had a particle size of 20 nm, purchased from Ningbo Jinlei Nanomaterials Co., Ltd.; the mineral oil was white oil with a flash point of 234℃, purchased from Suzhou Qiaosen Special Oils Co., Ltd.; and the maleic anhydride-grafted polypropylene had a melt index of 100 g / 10 min and a grafting rate of 1.03 wt%, purchased from Jiayirong Compatibilizer Co., Ltd., model CMG9801.

[0030] Preparation Example 1 (1) 96g of polypropylene, dicyclohexyl terephthalamide and maleic anhydride-grafted polypropylene were mixed in a mass ratio of 96:0.4:1, melted and granulated at 200℃ to obtain masterbatch. (2) Ultra-high molecular weight polyethylene was placed in mineral oil and swollen at 130°C for 20 minutes to obtain mineral oil-swollen ultra-high molecular weight polyethylene. (3) The masterbatch was mixed with nano-silica and mineral oil-swelled ultra-high molecular weight polyethylene at a mass ratio of 90:1:1, melted and granulated at 200°C to obtain silica-toughened polypropylene.

[0031] Preparation Example 2 (1) Mix 98g of polypropylene, dicyclohexyl terephthalamide and maleic anhydride-grafted polypropylene in a mass ratio of 98:1:3, melt and granulate at 200℃ to obtain masterbatch. (2) Ultra-high molecular weight polyethylene was placed in mineral oil and swollen at 130°C for 20 minutes to obtain mineral oil-swollen ultra-high molecular weight polyethylene. (3) The masterbatch was mixed with nano-silica and mineral oil-swelled ultra-high molecular weight polyethylene at a mass ratio of 95:5:5, melted and granulated at 200°C to obtain silica-toughened polypropylene.

[0032] Preparation Example 3 The difference from Preparation Example 1 is that in step (1), dicyclohexyl terephthalamide is not added. Instead, 96g of polypropylene and maleic anhydride-grafted polypropylene are mixed at a mass ratio of 96:1, melted and granulated at 200°C to obtain masterbatch.

[0033] Preparation Example 4 The difference from Preparation Example 1 is that in step (1), maleic anhydride-grafted polypropylene is not added. Instead, 96g of polypropylene and dicyclohexyl terephthalamide are mixed at a mass ratio of 96:0.4, melted and granulated at 200°C to obtain masterbatch.

[0034] Preparation Example 5 The difference from Preparation Example 1 is that in step (3), no mineral oil swelling treatment of ultra-high molecular weight polyethylene is added. Instead, the masterbatch and nano-silica are mixed at a mass ratio of 90:2, melted and granulated at 200°C to obtain silica-toughened polypropylene.

[0035] Preparation Example 6 The difference from Preparation Example 1 is that in step (3), no nano-silica is added. The masterbatch and mineral oil-swollen ultra-high molecular weight polyethylene are mixed at a mass ratio of 90:2, melted and granulated at 200°C to obtain silica-toughened polypropylene.

[0036] Example of preparation of graphene-modified carbon fiber In Examples 1-5 of the preparation of graphene-modified carbon fibers, the polypropylene powder was isotactic polypropylene with an isotacticity of 95% and a melt index of 2.5 g / 10 min, purchased from Yangzi Petrochemical Company, model F401; the carbon fiber length was divided into three specifications, and the tow specifications were composed of 12K 10%, 24K 10%, and 48K 80% by weight percentage, purchased from Zhongfu Shenying Carbon Fiber Co., Ltd., series SYT45; the graphene was nanosheets with an average thickness of about 5-7 nm, purchased from American Bailingwei Technology Company, model G434031.

[0037] Preparation Example 1 (1) Soak 7.5g of carbon fiber in acetone for 0.75h, then clean it with ethanol by ultrasonication and dry it. Then add the carbon fiber to 1L of 65% concentrated nitric acid solution for acid immersion treatment for 1h, then wash it with water and dry it to obtain pretreated carbon fiber. (2) Add 1g of graphene and 5g of sodium dodecylbenzenesulfonate to 1L of water, stir at 450r / min for 30min, and sonicate for 1h to obtain a graphene suspension. Add 1g of polypropylene powder during stirring and dry to obtain polypropylene / graphene composite powder. (3) Disperse the polypropylene / graphene composite powder obtained in step (2) in 130g of ethanol solution, then add the pretreated carbon fiber obtained in step (1), mix evenly, and dry to obtain graphene modified carbon fiber.

[0038] Preparation Example 2 (1) Soak 8g of carbon fiber in acetone for 1h, then ultrasonically clean and dry it with ethanol, then add the carbon fiber to 1L of 70% concentrated nitric acid solution for acid immersion treatment for 1h, then wash with water and dry to obtain pretreated carbon fiber. (2) Add 1.5g graphene and 7.5g sodium dodecylbenzenesulfonate to 1L of water, stir at 450r / min for 30min, and sonicate for 1h to obtain graphene suspension. Add 1.5g polypropylene powder during stirring and dry to obtain polypropylene / graphene composite powder. (3) Disperse the polypropylene / graphene composite powder obtained in step (2) in 170g of ethanol solution, then add the pretreated carbon fiber obtained in step (1), mix evenly, and dry to obtain graphene modified carbon fiber.

[0039] Preparation Example 3 (1) Soak 7g of carbon fiber in acetone for 0.5h, then ultrasonically clean and dry it with ethanol, then add the carbon fiber to 1L of 60% concentrated nitric acid solution for acid immersion treatment for 0.5h, then wash with water and dry to obtain pretreated carbon fiber. (2) Add 0.5g graphene and 2.5g sodium dodecylbenzenesulfonate to 1L of water, stir at 450r / min for 30min, and sonicate for 1h to obtain graphene suspension. Add 0.5g polypropylene powder during stirring and dry to obtain polypropylene / graphene composite powder. (3) Disperse the polypropylene / graphene composite powder obtained in step (2) in 100g of ethanol solution, then add the pretreated carbon fiber obtained in step (1), mix evenly, and dry to obtain graphene modified carbon fiber.

[0040] Preparation Example 4 (1) Soak 7.5g of carbon fiber in acetone for 0.75h, then clean it with ethanol by ultrasonication and dry it. Then add the carbon fiber to 1L of 65% concentrated nitric acid solution for acid immersion treatment for 1h, then wash it with water and dry it to obtain pretreated carbon fiber. (2) Add 1g of graphene and 5g of sodium dodecylbenzenesulfonate to 1L of water, stir at 450r / min for 30min, sonicate for 1h to obtain graphene suspension, and dry to obtain graphene powder. The graphene powder obtained in step (2) was dispersed in 130g of ethanol solution, and then the pretreated carbon fiber obtained in step (1) was added. After mixing evenly and drying, graphene-modified carbon fiber was obtained.

[0041] Preparation Example 5 (1) Soak 7.5g of carbon fiber in acetone for 0.75h, then clean it with ethanol by ultrasonication and dry it. Then add the carbon fiber to 1L of 65% concentrated nitric acid solution for acid immersion treatment for 1h, then wash it with water and dry it to obtain pretreated carbon fiber. (2) Add 1g of graphene to 1L of water, stir at 450r / min for 30min, sonicate for 1h to obtain graphene suspension, and dry to obtain graphene powder. (3) Disperse the graphene powder obtained in step (2) in 130g of ethanol solution, then add the pretreated carbon fiber obtained in step (1), mix evenly, and dry to obtain graphene modified carbon fiber. Example

[0042] In the following examples, polyamide 6 was purchased from Shanghai Heshibi Chemical Co., Ltd., model IMNC101; metallocene polyethylene elastomer was purchased from DuPont / Dow Elastomers, model Engage8842; EPDM was purchased from Bayer, model BunaAP 437K; talc was purchased from Liaoning Aihai Talc Co., Ltd., model AH51210L; pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] was purchased from Beijing Jiyi Chemical Co., Ltd., model KY-1010; and maleic anhydride-grafted polypropylene with a melt index of 100 g / 10 min and a grafting rate of 1.03 wt% was purchased from Jiayi Rong Compatibilizer Co., Ltd., model CMG9801.

[0043] Example 1: A lightweight, low-temperature impact-resistant bumper material. The raw material amounts are shown in Table 1. The silica-toughened polypropylene is prepared using the method described in Example 1 of the preparation of silica-toughened polypropylene. The graphene-modified carbon fiber is prepared using the method described in Example 1 of the preparation of graphene-modified carbon fiber. The elastomer includes mPE and EPDM in a mass ratio of 1:1. The antioxidant is antioxidant 1010. The compatibilizer is maleic anhydride-grafted polypropylene. The inorganic filler is talc.

[0044] The preparation method of the above-mentioned lightweight low-temperature impact resistant bumper material includes the following steps: mixing silica-toughened polypropylene, polyamide 6, graphene-modified carbon fiber, elastomer, antioxidant, compatibilizer and inorganic filler evenly, then adding it to a twin-screw extruder for extrusion, cooling and granulation, controlling the temperature of each zone to be 250℃, to obtain the bumper material.

[0045] Table 1 shows the raw material usage of bumper materials in Examples 1-6. Example 2: A lightweight, low-temperature impact-resistant bumper material, which differs from Example 1 in that the raw material amounts are shown in Table 1, and the mass ratio of silica-toughened polypropylene to elastomer is 5:1.

[0046] Example 3: A lightweight, low-temperature impact-resistant bumper material, which differs from Example 1 in that the raw material amounts are shown in Table 1, and the mass ratio of silica-toughened polypropylene to elastomer is 5:3.

[0047] Example 4: A lightweight, low-temperature impact-resistant bumper material, differing from Example 1 in that the raw material amounts are as shown in Table 1. The silica-toughened polypropylene is prepared using the method described in Example 2; the graphene-modified carbon fiber is prepared using the method described in Example 2; the elastomer comprises mPE and EPDM in a mass ratio of 1:0.5; the antioxidant is antioxidant 1010; the compatibilizer is maleic anhydride-grafted polypropylene; and the inorganic filler is talc.

[0048] Example 5: A lightweight, low-temperature impact-resistant bumper material, differing from Example 1 in that the raw material amounts are as shown in Table 1. The silica-toughened polypropylene is prepared using the method described in Example 1; the graphene-modified carbon fiber is prepared using the method described in Example 3; the elastomer comprises mPE and EPDM in a mass ratio of 1:0.8; the antioxidant is antioxidant 1010; the compatibilizer is maleic anhydride-grafted polypropylene; and the inorganic filler is talc.

[0049] Example 6: A lightweight, low-temperature impact-resistant bumper material, differing from Example 1 in that the raw material amounts are as shown in Table 1. The silica-toughened polypropylene is prepared using the method described in Example 2; the graphene-modified carbon fiber is prepared using the method described in Example 3; the elastomer comprises mPE and EPDM in a mass ratio of 1:0.8; the antioxidant is antioxidant 1010; the compatibilizer is maleic anhydride-grafted polypropylene; and the inorganic filler is talc.

[0050] Example 7: A lightweight, low-temperature impact-resistant bumper material, which differs from Example 1 in that the silica-toughened polypropylene is prepared using the method described in Example 3 of silica-toughened polypropylene preparation.

[0051] Example 8: A lightweight, low-temperature impact-resistant bumper material, which differs from Example 1 in that the silica-toughened polypropylene is prepared using the method described in Example 4 of the silica-toughened polypropylene preparation.

[0052] Example 9: A lightweight, low-temperature impact-resistant bumper material, which differs from Example 1 in that the silica-toughened polypropylene is prepared using the method described in Example 5 of the silica-toughened polypropylene preparation.

[0053] Example 10: A lightweight, low-temperature impact-resistant bumper material, which differs from Example 1 in that the graphene-modified carbon fiber is prepared using the method described in Example 4 of graphene-modified carbon fiber preparation.

[0054] Example 11: A lightweight, low-temperature impact-resistant bumper material, which differs from Example 1 in that the graphene-modified carbon fiber is prepared using the method described in Example 5 of graphene-modified carbon fiber preparation.

[0055] Example 12: A lightweight, low-temperature impact-resistant bumper material, which differs from Example 1 in that the elastomer comprises mPE and EPDM in a mass ratio of 1:0.1.

[0056] Example 13: A lightweight, low-temperature impact-resistant bumper material, which differs from Example 1 in that the elastomer comprises mPE and EPDM in a mass ratio of 1:1.2.

[0057] Example 14: A lightweight, low-temperature impact-resistant bumper material, which differs from Example 1 in that the elastomer is mPE.

[0058] Example 15: A lightweight, low-temperature impact-resistant bumper material, which differs from Example 1 in that the elastomer is SBS, which was purchased from Sinopec Baling Petrochemical Branch, model YH-792.

[0059] Comparative Example Comparative Example 1: A lightweight, low-temperature impact-resistant bumper material, which differs from Example 1 in that the silica-toughened polypropylene is prepared using the method described in Example 6 of the silica-toughened polypropylene preparation.

[0060] Comparative Example 2: A lightweight, low-temperature impact-resistant bumper material, which differs from Example 1 in that the silica-toughened polypropylene is replaced by an equal amount of polypropylene. The polypropylene is isotactic polypropylene with an isotacticity of 95% and a melt flow index of 2.5 g / 10 min, purchased from Yangzi Petrochemical Company, model F401.

[0061] Comparative Example 3: A lightweight, low-temperature impact-resistant bumper material, which differs from Example 1 in that graphene-modified carbon fiber is replaced by an equal amount of carbon fiber; the carbon fiber is pretreated by the following method: 7.5g of carbon fiber is soaked in acetone for 0.75h, then ultrasonically cleaned and dried with ethanol, and then the carbon fiber is added to 1L of 65% concentrated nitric acid solution for acid immersion treatment for 1h, then washed with water and dried.

[0062] Comparative Example 4: A lightweight, low-temperature impact-resistant bumper material, which differs from Example 1 in that it does not contain graphene-modified carbon fiber.

[0063] Performance testing Lightweight low-temperature impact resistant bumper materials were prepared according to the methods in the examples and comparative examples, and their performance was tested according to the following methods. The test results are recorded in Table 2.

[0064] 1. Density: Tested according to GB / T 1033-2008 "Determination of density of non-foamed plastics"; 2. Tensile strength: Tested according to GB / T 1040-2018 "Determination of tensile properties of plastics", using type 1A specimen, tensile speed 50mm / min; 3. Impact strength: Tested according to GB / T 1043-2008 "Impact Test Method for Simply Supported Beams of Rigid Plastics"; 4. Low-temperature impact strength reduction rate: The impact strength of the bumper material is tested at room temperature and at -40℃. The low-temperature impact strength reduction rate is calculated according to the following formula: (room temperature impact strength - low-temperature impact strength) / room temperature impact strength × 100%. 5. Flexural modulus: Tested in accordance with GB / T 9341-2008 "Determination of Flexural Properties of Plastics".

[0065] Table 2. Mechanical property test results of bumper materials prepared in the examples and comparative examples. As can be seen from Table 2, the lightweight, low-temperature impact-resistant bumper materials prepared in Examples 1-6 of this application have good lightweight properties, tensile strength, rigidity, and toughness, with a density of 0.95-1.11 g / cm³. 3 The tensile strength is 28.1-31.3 MPa, the flexural modulus is 1319-1345 MPa, and the notched impact strength of the cantilever beam (23℃) reaches 53.5-57.1 KJ / m. 2 The low-temperature impact strength reduction rate (-40℃) was 24.91-27.23%, indicating that the prepared bumper material has lightweight characteristics and good toughness at low temperatures; this shows that graphene-modified carbon fiber can enhance the rigidity and toughness of polypropylene material in composite materials, and can obtain lightweight and high-toughness bumper material by combining it with elastomers and other components.

[0066] In Example 7, no nucleating agent dicyclohexyl terephthalamide was added during the preparation of silica-toughened polypropylene. As shown in Table 2, compared with Example 1, the bumper material prepared in Example 7 has a higher density, but lower flexural modulus, tensile strength, and impact strength. This indicates that using dicyclohexyl terephthalamide to induce the formation of β crystals in polypropylene helps to improve the lightweight, rigidity, tensile strength, and toughness of the bumper material.

[0067] In Example 8, during the preparation of silica-toughened polypropylene, no compatibilizer maleic anhydride-grafted polypropylene was added. As shown in Table 2, compared with Example 1, the bumper material obtained in Example 8 had increased density, while tensile strength, flexural modulus, and impact strength decreased. This indicates that using maleic anhydride-grafted polypropylene as a compatibilizer helps to enhance the compatibility of the various components within the polypropylene, thereby improving the lightweight, tensile strength, rigidity, and toughness of the bumper material.

[0068] In Example 9, during the preparation of silica-toughened polypropylene, ultra-high molecular weight polyethylene without mineral oil swelling treatment was used. As shown in Table 2, compared with Example 1, the bumper material obtained in Example 9 had increased density, while tensile strength, flexural modulus, and impact strength decreased. This indicates that using ultra-high molecular weight polyethylene with added mineral oil for thermal swelling treatment helps to improve the lightweight of the bumper material and enhance its tensile strength, rigidity, and toughness.

[0069] In Example 10, no polypropylene powder was added during the preparation of graphene-modified carbon fiber. As shown in Table 2, compared with Example 1, the tensile strength, flexural modulus, and impact strength of the bumper material obtained in Example 10 all decreased. This indicates that the addition of polypropylene powder can improve the tensile strength, rigidity, and toughness of the bumper material by increasing the bonding strength between graphene and carbon fiber.

[0070] In Example 11, no sodium dodecylbenzenesulfonate or polypropylene powder was added during the preparation of graphene-modified carbon fiber. As shown in Table 2, compared with Example 1, the tensile strength, flexural modulus, and impact strength of the bumper material obtained in Example 11 all decreased. This indicates that sodium dodecylbenzenesulfonate and polypropylene powder can help disperse graphene powder and increase the bonding strength between graphene and carbon fiber, thereby improving the tensile strength, rigidity, and toughness of the bumper material.

[0071] In Example 12, during the preparation of a lightweight, low-temperature impact-resistant bumper material, the mass ratio of elastomer mPE to EPDM was changed to 1:0.1. As shown in Table 2, compared with Example 1, the tensile strength, flexural modulus, and impact strength of the bumper material obtained in Example 12 all decreased, indicating that adding mPE and EPDM at a certain mass ratio helps to improve the tensile strength, rigidity, and toughness of the bumper material.

[0072] In Example 13, during the preparation of a lightweight, low-temperature impact-resistant bumper material, the mass ratio of elastomer mPE to EPDM was changed to 1:1.2. As shown in Table 2, compared with Example 1, the tensile strength, flexural modulus, impact strength, and low-temperature impact strength of the bumper material obtained in Example 13 all decreased. This indicates that increasing EPDM helps to improve the tensile strength, rigidity, and toughness of the bumper material, but its low-temperature resistance decreases.

[0073] In Example 14, only the elastomer mPE was added during the preparation of the lightweight, low-temperature impact-resistant bumper material. As shown in Table 2, compared with Example 1, the tensile strength, flexural modulus, and impact strength of the bumper material obtained in Example 14 decreased, indicating that the combination of mPE and EPDM helps to improve the tensile strength, rigidity, and toughness of the bumper material.

[0074] In Example 15, during the preparation of a lightweight, low-temperature impact-resistant bumper material, the type of elastomer was changed to SBS. As shown in Table 2, compared with Example 1 and Example 14, the bumper material obtained in Example 15 had increased density, while tensile strength, flexural modulus, and impact strength decreased. This indicates that mPE, as an elastomer in composite materials, helps to improve the lightweight, tensile strength, rigidity, and toughness of the bumper material.

[0075] In Comparative Example 1, no nano-silica was added during the preparation of silica-toughened polypropylene. The masterbatch and mineral oil-swelled ultra-high molecular weight polyethylene were mixed in a certain mass ratio. As shown in Table 2, compared with Example 1, the tensile strength, flexural modulus and impact strength of the bumper material obtained in Comparative Example 1 decreased significantly, indicating that the addition of nano-silica helps to improve the tensile strength, rigidity and toughness of the bumper material.

[0076] In Comparative Example 2, during the preparation of a lightweight, low-temperature impact-resistant bumper material, silica-toughened polypropylene was replaced by an equal amount of polypropylene. As shown in Table 2, compared to Example 1, the tensile strength, flexural modulus, and impact strength of the bumper material obtained in Comparative Example 2 decreased significantly, indicating that adding silica-toughened polypropylene helps to improve the tensile strength, rigidity, and toughness of the bumper material.

[0077] In the preparation of lightweight, low-temperature impact-resistant bumper material in Comparative Example 3, graphene-modified carbon fiber was replaced by an equal amount of nitric acid-treated carbon fiber. As shown in Table 2, compared with Example 1, the tensile strength, flexural modulus, and impact strength of the bumper material obtained in Comparative Example 3 were significantly reduced, indicating that using graphene to modify carbon fiber helps to improve the tensile strength, rigidity, and toughness of the bumper material.

[0078] In the preparation of lightweight, low-temperature impact-resistant bumper material, Comparative Example 4 did not add graphene-modified carbon fiber. As shown in Table 2, compared with Example 1, the tensile strength, flexural modulus, and impact strength of the bumper material obtained in Comparative Example 4 decreased significantly, indicating that adding graphene-modified carbon fiber helps to improve the tensile strength, rigidity, and toughness of the bumper material.

[0079] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A lightweight, low-temperature impact-resistant bumper material, characterized in that, The raw materials include the following parts by weight: 45-70 parts of silica-toughened polypropylene, 10-20 parts of polyamide 6, 10-35 parts of elastomer, 30-45 parts of graphene-modified carbon fiber, 5-10 parts of inorganic filler, 0.5-2 parts of antioxidant, and 5-10 parts of compatibilizer.

2. The lightweight, low-temperature impact-resistant bumper material according to claim 1, characterized in that, The method for preparing the silica-toughened polypropylene includes the following steps: (1) Polypropylene, dicyclohexyl terephthalamide and maleic anhydride-grafted polypropylene are mixed, melted and granulated in a mass ratio of 96-98:0.4-1:1-3 to obtain masterbatch; (2) The masterbatch is mixed with nano-silica and mineral oil-swelled ultra-high molecular weight polyethylene at a mass ratio of 90-95:1-5:1-5, melted and granulated to obtain the silica-toughened polypropylene.

3. The lightweight, low-temperature impact-resistant bumper material according to claim 1, characterized in that, The raw materials for the graphene-modified carbon fiber include polypropylene, graphene, and carbon fiber, with a mass ratio of 0.5-1.5:0.5-1.5:7-8.

4. The lightweight, low-temperature impact-resistant bumper material according to claim 3, characterized in that, The method for preparing the graphene-modified carbon fiber includes the following steps: The carbon fiber is soaked in acetone for 0.5-1 hour, then ultrasonically cleaned and dried with ethanol, and then added to a 60-70% concentrated nitric acid solution for acid immersion treatment for 0.5-1.5 hours, followed by water washing and drying to obtain pretreated carbon fiber. Graphene and sodium dodecylbenzenesulfonate were added to water, stirred, and ultrasonically treated to obtain a graphene suspension. Polypropylene powder was added while stirring the graphene suspension, and then dried to obtain a polypropylene / graphene composite powder. Polypropylene / graphene composite powder was dispersed in an ethanol solution, then pretreated carbon fibers were added, mixed evenly, and dried to obtain graphene-modified carbon fibers.

5. The lightweight, low-temperature impact-resistant bumper material according to claim 1, characterized in that, The elastomer comprises metallocene polyethylene elastomer and EPDM in a mass ratio of 1:0.5-1.

6. The lightweight, low-temperature impact-resistant bumper material according to claim 1, characterized in that, The mass ratio of the silica-toughened polypropylene to the elastomer is 5:

2.

7. The lightweight, low-temperature impact-resistant bumper material according to claim 1, characterized in that, The inorganic filler is selected from at least one of talc, calcium carbonate, mica and kaolin.

8. The lightweight, low-temperature impact-resistant bumper material according to claim 1, characterized in that, The compatibilizer is maleic anhydride-grafted polypropylene.

9. The lightweight, low-temperature impact-resistant bumper material according to claim 1, characterized in that, The antioxidant is any one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine, and tris(2,4-di-tert-butylphenyl)phosphite.

10. A method for preparing a lightweight, low-temperature impact-resistant bumper material according to any one of claims 1-9, characterized in that, Includes the following steps: The silica-toughened polypropylene, polyamide 6, graphene-modified carbon fiber, elastomer, antioxidant, compatibilizer and inorganic filler are mixed evenly, melt-extruded at 215℃-255℃, cooled, pelletized and dried to obtain the bumper material.

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