Low-temperature blasting polypropylene composite material, and preparation method therefor and use thereof

Abstract

Disclosed in the present invention is a low-temperature blasting polypropylene composite material. The low-temperature blasting polypropylene composite material comprises the following components, in parts by weight: 55-80 parts of a polypropylene, 5-20 parts of a filler, 1-5 parts of special fibers, 15-20 parts of a flexibilizer, 0.1-0.5 parts of a mixed compatilizer and 0-1.2 parts of an auxiliary agent, wherein the polypropylene is a binary block co-polypropylene synthesized by ethylene and propylene; the special fibers are ultra-high molecular weight polyethylene fibers having a fiber fineness of 400-800 deniers; and the mixed compatilizer comprises a polyethylene-grafted maleic anhydride and a polypropylene-grafted maleic anhydride. In the present invention, a specific binary block co-polypropylene and the ultra-high molecular weight polyethylene fibers having a specific fiber fineness are used to be matched with the specific mixed compatilizer, such that it is ensured that the polypropylene composite material has excellent tensile strength and bending properties while having excellent low-temperature bursting performance.

Description

A low-temperature blasting polypropylene composite material and its preparation method and application Technical Field

[0001] The present invention belongs to the technical field of polypropylene composite materials, and more specifically, relates to a low-temperature explosion polypropylene composite material and a preparation method and application thereof. Background Art

[0002] Polypropylene, with its low density, high cost-effectiveness, excellent heat resistance, rigidity, chemical resistance, and ease of processing, molding, and recycling, has been widely used in automobiles, becoming the most widely used and fastest-growing automotive plastic. The rapid development of the automotive industry in recent years has placed increasingly stringent requirements on interior and exterior materials, such as the current industry-wide requirement for low-temperature blast-resistant rigid instrument panels, pillars, and other interior components.

[0003] Currently, the low-temperature blasting formulations in the modified polypropylene industry are mostly composed of talc, block copolymer polypropylene, POE (ethylene-octene random copolymer, typically added at a level of 25% or more), antioxidants, lubricants, and light stabilizers. Due to the high level of POE added, the strength and modulus of existing low-temperature blasting polypropylene materials are often low.

[0004] Therefore, how to provide a low-temperature explosion polypropylene composite material having excellent low-temperature explosion performance and excellent tensile and bending properties has become a technical problem that needs to be solved urgently. Summary of the Invention

[0005] In view of the above-mentioned existing technical problems, the primary object of the present invention is to provide a low-temperature explosion polypropylene composite material, which has more excellent low-temperature explosion performance and also has excellent tensile and bending properties.

[0006] The second object of the present invention is to provide a method for preparing a low-temperature explosion polypropylene composite material.

[0007] The third object of the present invention is to provide a low-temperature explosion polypropylene composite material for use in the automotive industry.

[0008] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0009] A high-efficiency, low-temperature explosion-resistant polypropylene composite material comprises the following components, measured by weight: 55-80 parts of polypropylene, 5-20 parts of filler, 1-5 parts of special fiber, 15-20 parts of toughening agent, 0.1-0.5 parts of mixed compatibilizer, and 0-1.2 parts of auxiliary agent; the polypropylene is a binary block copolymer polypropylene synthesized from ethylene and propylene; the special fiber is an ultra-high molecular weight polyethylene fiber with a fiber fineness of 400-800 denier; and the mixed compatibilizer comprises polyethylene grafted with maleic anhydride and polypropylene grafted with maleic anhydride.

[0010] Ultra-high molecular weight polyethylene (UHMWPE) fibers offer superior reinforcement and toughening properties compared to conventional UHMWPE powders. This is because the one-dimensional fiber reinforcement of UHMWPE fibers is more capable of supporting the entire base resin than spherical powders. However, the inventors discovered that UHMWPE fibers exhibit poor compatibility with polypropylene in polypropylene resin systems, significantly impacting the low-temperature blasting performance, tensile properties, and flexural properties of the polypropylene composite.

[0011] Through research, the inventors discovered that ultra-high molecular weight polyethylene fibers with a fiber fineness of 400 to 800 denier exhibit excellent processability and dispersion in polypropylene resin systems. However, ultra-high molecular weight polyethylene fibers with a fiber fineness above this range exhibit poor reinforcement and toughening effects on polypropylene composites, significantly impacting the low-temperature blasting performance of the composite. Furthermore, the inventors discovered that using polyethylene grafted maleic anhydride and polypropylene grafted maleic anhydride as a mixed compatibilizer in a polypropylene system not only exhibits excellent compatibility with the ultra-high molecular weight polyethylene fibers, but also allows the two compatibilizers to be linked together via maleic anhydride, further enhancing the compatibilization effect.

[0012] The present invention uses binary block copolymer polypropylene synthesized from ethylene and propylene as the base material of the polypropylene composite material, and compounding it with ultra-high molecular weight polyethylene fibers of a specific fiber fineness and a mixed compatibilizer of polyethylene grafted maleic anhydride and polypropylene grafted maleic anhydride. The prepared polypropylene composite material not only has more excellent low-temperature blasting performance, but also has excellent tensile and bending properties.

[0013] Preferably, the polypropylene has a melt flow rate of 50 to 105 g / 10 min at 230° C. and 2.16 kg; more preferably, the polypropylene has a melt flow rate of 60 to 100 g / 10 min at 230° C. and 2.16 kg. The melt flow rate (MFR) of the polypropylene is measured according to the standard method for melt mass flow rate of plastic pellets - ISO 1133-1:2011.

[0014] Specifically, in the low-temperature explosion polypropylene composite material, the content of polypropylene is not less than 58.6%.

[0015] The melt flow rate of the polypropylene in the present invention can be 50 g / 10 min, 60 g / 10 min, 70 g / 10 min, 80 g / 10 min, 90 g / 10 min, 100 g / 10 min, etc., or an interval range formed by any of the above values, such as 60-80 g / 10 min, 80-100 g / 10 min, etc., but the present invention is not limited thereto.

[0016] Preferably, the polypropylene has a dispersion index (PDI) of 6 to 10. PDI = Mw / Mn (weight average molecular weight / number average molecular weight), known as the molecular weight dispersion index of the polymer. The weight average molecular weight and number average molecular weight of the polymer are tested using a high-temperature GPC method.

[0017] Preferably, the mass ratio of the polyethylene grafted maleic anhydride to the polypropylene grafted maleic anhydride is 1:3 to 3:1, and the mass ratio of the polyethylene grafted maleic anhydride to the polypropylene grafted maleic anhydride is 1:2 to 2:1. Within this preferred range, the polypropylene composite material exhibits even better high-efficiency, low-temperature blasting performance, as well as excellent tensile strength and flexural properties.

[0018] Preferably, the grafting rate of maleic anhydride in the polyethylene grafted with maleic anhydride is 0.5 to 1.6%. More preferably, the grafting rate of maleic anhydride in the polyethylene grafted with maleic anhydride is 0.8 to 1.2%.

[0019] Preferably, the grafting rate of maleic anhydride in the polypropylene grafted with maleic anhydride is 0.5 to 1.6%. More preferably, the grafting rate of maleic anhydride in the polypropylene grafted with maleic anhydride is 0.8 to 1.2%.

[0020] Specifically, the polyethylene grafted maleic anhydride and polypropylene grafted maleic anhydride of the present invention can be obtained commercially or prepared by methods known in the art, such as melt grafting, but the preparation method is not limited thereto.

[0021] Specifically, the grafting rate of maleic anhydride in the polyethylene grafted maleic anhydride and the polypropylene grafted maleic anhydride is detected by acid-base titration.

[0022] Preferably, the filler is one or more of basic magnesium sulfate whiskers, talc, and calcium carbonate; the filler D 50 The particle size is 0.5~12μm.

[0023] Preferably, the D of the talc 50The particle size is 0.65 to 1 μm. Under this preferred particle size, the polypropylene composite material has better tensile strength and bending properties.

[0024] Preferably, the D of the calcium carbonate 50 The particle size is 4 to 8 μm. Under this preferred particle size, the polypropylene composite material has better tensile strength and bending properties.

[0025] Specifically, the laser particle size analysis method was used to test the D 50 Particle size.

[0026] Preferably, the number average molecular weight of the ultra-high molecular weight polyethylene fiber is 1 to 3 million. The number average molecular weight of the ultra-high molecular weight polyethylene fiber is tested using a high temperature GPC method.

[0027] Preferably, the toughening agent is selected from one or both of ethylene-octene random copolymer and ethylene-octene block copolymer.

[0028] Preferably, the auxiliary agent includes one or more of a lubricant, an antioxidant, and a light stabilizer.

[0029] Further preferably, the lubricant includes but is not limited to amide lubricants, stearate lubricants, etc. The antioxidant includes but is not limited to hindered phenol antioxidants, phosphite antioxidants, etc. The light stabilizer includes but is not limited to hindered amine light stabilizers and / or benzoate light stabilizers, such as 2,2,6,6-tetramethyl-4-piperidinyl stearate (Light Stabilizer 3853) and / or 3,5-di-tert-butyl-4-hydroxybenzoic acid hexadecyl (Light Stabilizer 2908), but the present application is not limited thereto.

[0030] Furthermore, the present invention also claims protection for a method for preparing a low-temperature explosion polypropylene composite material, which comprises mixing polypropylene, special fibers, a toughening agent, a mixed compatibilizer, and an additive, adding a filler, mixing, and melt-extruding to prepare the low-temperature explosion polypropylene composite material.

[0031] Preferably, the rotation speed during mixing is 200 to 300 rpm.

[0032] Preferably, a twin-screw extruder is used for extrusion, and the length-to-diameter ratio of the twin-screw extruder is 48 to 56:1.

[0033] Preferably, the melt extrusion adopts a triple vacuum process, and the vacuum degree is controlled to be ≤-0.08 MPa.

[0034] Preferably, the temperature of the melt extrusion is 170-210° C. Furthermore, the temperature from the feeding section to the die head is 170° C., 200° C., 200° C., 210° C., 210° C., 205° C., 205° C., 205° C., 200° C., and 200° C. in sequence.

[0035] Furthermore, the present invention also seeks protection for the use of a low-temperature explosive polypropylene composite material in the automotive industry. Specifically, the low-temperature explosive polypropylene composite material can be used as automotive interior components, including but not limited to low-temperature explosive hard instrument panels, pillars, and other automotive interior components, particularly in applications requiring high low-temperature explosiveness and mechanical properties.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The present invention uses binary block copolymer polypropylene synthesized from ethylene and propylene as the base material of the polypropylene composite material, and compounding it with ultra-high molecular weight polyethylene fibers of a specific fiber fineness and a mixed compatibilizer of polyethylene grafted maleic anhydride and polypropylene grafted maleic anhydride. The prepared polypropylene composite material not only has more excellent high-efficiency low-temperature blasting performance, but also has excellent tensile and bending properties. DETAILED DESCRIPTION

[0038] The present invention will be further described below with reference to the accompanying drawings and specific examples, but the examples do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0039] Description of raw materials for embodiments and comparative examples:

[0040] Polypropylene 1, block copolymer polypropylene synthesized from ethylene and propylene, model: BI871, MFR (230°C, 2.16 kg) = 60 g / 10 min, PDI = 7.5, manufacturer: Hanwha Total Petrochemical.

[0041] Polypropylene 2, block copolymer polypropylene synthesized from ethylene and propylene, model: 7905E1, MFR (230°C, 2.16 kg) = 100 g / 10 min, PDI = 8.6, manufacturer: ExxonMobil.

[0042] Special fiber 1: ultra-high molecular weight polyethylene fiber, UHMWPE, fiber fineness 800 denier, number average molecular weight 2 million, manufacturer: Beijing Tongyizhong New Materials Technology Co., Ltd.

[0043] Special fiber 2: ultra-high molecular weight polyethylene fiber, UHMWPE, fiber fineness 700 denier, number average molecular weight 1.5 million, manufacturer: Beijing Tongyizhong New Materials Technology Co., Ltd.

[0044] Special fiber 3: ultra-high molecular weight polyethylene fiber, UHMWPE, fiber fineness 400 denier, number average molecular weight 1 million, manufacturer: Beijing Tongyizhong New Materials Technology Co., Ltd.

[0045] Special fiber 4: ultra-high molecular weight polyethylene fiber, UHMWPE, fiber fineness 1600 denier, number average molecular weight 3 million, manufacturer: Beijing Tongyizhong New Materials Technology Co., Ltd.

[0046] Ultra-high molecular weight polyethylene, UHMWPE, model: U010P, number average molecular weight 1 million, manufacturer: Korea Petrochemical.

[0047] Toughener 1, ethylene-octene random copolymer (POE), model: Engage 8842, manufacturer: Dow Chemical.

[0048] Toughener 2, ethylene-octene block copolymer (OBC), model: Infuse 9107, manufacturer: Dow Chemical.

[0049] Mixed compatibilizer 1: The mass ratio of polyethylene grafted maleic anhydride and polypropylene grafted maleic anhydride is 1:1; among them, the polyethylene grafted maleic anhydride is 1, and the grafting rate is 0.8% (detected by acid-base titration method).

[0050] Polypropylene grafted with maleic anhydride 1, grafting rate 1.2%, model: PP-g-MAH (B2), manufacturer: Coase Chemical Co., Ltd.

[0051] Preparation method of polyethylene grafted maleic anhydride 1:

[0052] A-70 parts of high-density polyethylene HMA026, 0.6 parts of maleic anhydride and 0.41 parts of di-tert-butyl peroxide were placed in a Haake torque rheometer at 170°C for melt grafting; after the melt grafting reaction was completed for 25 minutes, a grafted mixture was obtained;

[0053] B-Take out the grafted mixture, press it into tablets, and crush it into granules. Purify the grafted mixture, weigh 30g of the granular grafted mixture, put the grafted mixture into a flask filled with 850mL of xylene solvent, heat it at 95℃ for 3h to completely dissolve the grafted mixture, cool it to room temperature, add 4000mL of acetone, precipitate, filter, and dry to obtain polyethylene grafted maleic anhydride 1, which is set aside for later use.

[0054] Mixed compatibilizer 2: The difference between mixed compatibilizer 2 and mixed compatibilizer 1 is that the mass ratio of polyethylene grafted maleic anhydride 1 and polypropylene grafted maleic anhydride 1 is 1:3.

[0055] Mixed compatibilizer 3: The difference between mixed compatibilizer 3 and mixed compatibilizer 1 is that the mass ratio of polyethylene grafted maleic anhydride 1 and polypropylene grafted maleic anhydride 1 is 3:1.

[0056] Mixed compatibilizer 4: The difference between mixed compatibilizer 4 and mixed compatibilizer 1 is that polyethylene is grafted onto maleic anhydride 2, and the grafting rate is 0.5% (detected by acid-base titration method).

[0057] Preparation method of polyethylene grafted maleic anhydride 2: The preparation method is the same as the above polyethylene grafted maleic anhydride 1, except that 0.375 parts of maleic anhydride and 0.26 parts of di-tert-butyl peroxide are used.

[0058] Mixed compatibilizer 5: The difference between mixed compatibilizer 5 and mixed compatibilizer 1 is that polyethylene is grafted with maleic anhydride 3, and the grafting rate is 1.6% (detected by acid-base titration method).

[0059] The preparation method of polyethylene grafted maleic anhydride 3 is the same as the preparation method of polyethylene grafted maleic anhydride 1, except that 1.2 parts of maleic anhydride and 0.82 parts of di-tert-butyl peroxide are used.

[0060] Mixed compatibilizer 6: The difference between mixed compatibilizer 6 and mixed compatibilizer 1 is that polyethylene is grafted with maleic anhydride 4, and the grafting rate is 1.2% (detected by acid-base titration method).

[0061] Preparation method of polyethylene grafted maleic anhydride 4: The preparation method is the same as the above polyethylene grafted maleic anhydride 1, except that 0.9 parts of maleic anhydride and 0.62 parts of di-tert-butyl peroxide are used.

[0062] Metallocene ethylene-propylene copolymer, model Vistamaxx 6202, ethylene content 15%, manufacturer: ExxonMobil.

[0063] Talc 1, D 50 Particle size = 6μm, model: TYT-777A, manufacturer: Liaoning Tianyuan.

[0064] Talc 2, D 50 Particle size = 0.65 μm, model: HTPultra5L, manufacturer: Yimifabi.

[0065] Calcium carbonate 1, model: heavy calcium carbonate, D 50 Particle size = 6μm, manufacturer: Guangxi Xincai Mining.

[0066] Calcium carbonate 2, model: heavy calcium carbonate, D 50 Particle size = 12μm, manufacturer: Guangxi Xincai Mining.

[0067] Antioxidant 1, hindered phenol antioxidant, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, commercially available.

[0068] Antioxidant 2, phosphite antioxidant, tris[2,4-di-tert-butylphenyl]phosphite, commercially available.

[0069] Light stabilizer, model: UV-3808PP5, commercially available.

[0070] Lubricant: calcium stearate, commercially available.

[0071] Unless otherwise specified, the components used in the parallel examples and comparative examples (eg, antioxidants, light stabilizers, lubricants, etc.) are all the same commercially available products.

[0072] Example 1

[0073] The weight parts of the raw materials used in Example 1 are shown in Table 1.

[0074] A method for preparing a low-temperature explosion polypropylene composite material, comprising the following steps:

[0075] According to the weight parts of Table 1, polypropylene, special fiber, toughening agent, mixed compatibilizer, antioxidant, light stabilizer and lubricant were weighed and mixed in a high-speed mixer (200-300 rpm) for 3-5 minutes, and then filler (calcium carbonate or talc) was added and mixed in a high-speed mixer (200-300 rpm) for 3-5 minutes. The mixture was then added to a twin-screw extruder (aspect ratio 52:1) for melt extrusion. The extrusion adopted a double vacuum process and the vacuum degree was ≤-0.08 MPa. The temperature of the twin-screw extruder was 170°C, 200°C, 200°C, 210°C, 210°C, 205°C, 205°C, 205°C, 200°C, and 200°C from the feeding section to the die. Granulation, drying and cooling were performed to obtain a low-temperature blasting polypropylene composite material.

[0076] Examples 2 to 13

[0077] The weight parts of the raw materials used in the following examples are shown in Table 1.

[0078] The specific preparation steps of the following examples are the same as those of Example 1.

[0079] Comparative Examples 1 to 8

[0080] The weight parts of the raw materials used in the following comparative examples are shown in Table 2.

[0081] The specific preparation steps of each comparative example are the same as those of Example 1.

[0082] Table 1 is the formula components of each embodiment:

[0083] Table 1

[0084] Table 2 shows the formula components of each comparative example:

[0085] Table 2

[0086] The raw materials used in the above examples and comparative examples and the prepared low-temperature explosion polypropylene composite materials were tested according to the following test methods:

[0087] 1. Tensile strength: tested in accordance with ISO 527-2:2019, tensile speed 50mm / min, 1A spline.

[0088] 2. Bending performance: tested in accordance with ISO 178:2019, bending speed 2mm / min.

[0089] 3. Izod notched impact: Tested in accordance with ISO 180:2019, Type A notch.

[0090] 4. Low-temperature -40°C multi-axial impact: Refer to ISO 6603-2:2000 standard test (evaluation of 2mm thick square plates, 4.4m / s impact velocity, performance is divided into four grades from best to worst: YD, YS, YU, and NY; the YD fracture mode is shown in the curve as a clear yield point, the fracture surface has a uniform ductility throughout the entire depth, and the penetration hole has only a single crack ring; the YS fracture mode is shown in the curve as a clear yield point, the fracture surface has stable but inconsistent ductility, which can be evenly distinguished, and the penetration hole has two non-repeating crack rings; the YU fracture mode is shown in the curve as a clear yield point, unstable ductile fracture on the fracture surface, with possible ductile fracture areas, two non-repeating crack rings in the penetration hole, or unstable non-ductile fracture at the penetration site, with obvious cracks but no separation from the sample; the NY fracture mode is shown as no yield). It is generally believed that the failure modes YD and YS meet the blasting requirements, while YU and NY do not.

[0091] Table 3 and Table 4 are the performance test results of each embodiment and comparative example respectively.

[0092] Table 3

[0093] Table 4

[0094] From the data of Examples 1 to 13, it can be seen that the present invention uses a specific binary block copolymer polypropylene, an ultra-high molecular weight polyethylene fiber of a specific fiber fineness, and a specific mixed compatibilizer to ensure that the polypropylene composite material has excellent low-temperature blasting performance while also having excellent tensile strength and bending properties. The -40°C low-temperature multiaxial / failure form of the prepared low-temperature blasting polypropylene composite material is YD&YS, which can meet the blasting requirements. In terms of mechanical properties, the tensile strength of the polypropylene composite material is greater than 24MPa, the flexural modulus is greater than 1458MPa, and the cantilever beam notched impact is greater than 11KJ / m 2 .

[0095] It can be seen from Examples 1, 2 and 3, and 4 and 5 that when the mass ratio of polyethylene grafted maleic anhydride and polypropylene grafted maleic anhydride in the mixed compatibilizer is 1:2 to 2:1, or when the grafting rate of polyethylene grafted maleic anhydride and polypropylene grafted maleic anhydride is 0.5 to 1.6%, the tensile strength, flexural properties and Izod notched impact strength of the prepared polypropylene composite material are better.

[0096] As can be seen from Examples 1, 6, 7, and Comparative Example 5, as the fineness of the ultra-high molecular weight polyethylene fibers decreases, the mechanical properties of the polypropylene composite material gradually improve. However, when the fineness of the ultra-high molecular weight polyethylene fibers exceeds 400 to 800 denier (e.g., 1600 denier), the dispersion and processability of the ultra-high molecular weight polyethylene fibers in the polypropylene resin system are poor due to their high fineness, resulting in a significant decrease in the tensile strength, flexural strength, flexural modulus, and notched Izod impact of the prepared composite material.

[0097] It can be seen from Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 that when the polypropylene system lacks ultra-high molecular weight polyethylene fiber and / or mixed compatibilizer, the prepared polypropylene composite material cannot achieve the technical effect of the present invention, indicating that the present invention requires the use of ultra-high molecular weight polyethylene fiber and mixed compatibilizer in combination to ensure the low-temperature blasting performance and mechanical properties of the polypropylene composite material.

[0098] It can be seen from Example 1 and Comparative Example 4 that when non-fiber ultra-high molecular weight polyethylene is used in the polypropylene composite material system, not only the tensile strength, flexural strength, flexural modulus and cantilever beam notched impact of the polypropylene composite material are significantly reduced, but the low-temperature blasting performance is also difficult to achieve the technical effect of the present invention.

[0099] It can be seen from Example 1, Comparative Example 6 and Comparative Example 7 that a single mixed compatibilizer is difficult to achieve the compatibility and dispersion of the components in the polypropylene system of the present invention, and the prepared polypropylene composite material is difficult to achieve the technical effect of the present invention.

[0100] It can be seen from Example 1 and Comparative Example 8 that it is difficult to achieve the technical effect by combining the metallocene ethylene-propylene copolymer with the ultra-high molecular weight polyethylene fiber of the polypropylene composite material system of the present invention.

[0101] The foregoing examples are merely illustrative, serving to illustrate some of the features of the method of the present invention. The appended claims are intended to claim the widest possible scope that can be envisioned, and the embodiments presented herein are demonstrated by the applicant's actual experimental results. Therefore, the applicant intends that the appended claims are not limited by the selection of examples illustrating the features of the present invention. Some numerical ranges used in the claims also include subranges therein, and variations in these ranges should also be interpreted as being covered by the appended claims where possible.

Claims

1. A low-temperature explosion polypropylene composite material, characterized in that: The composition includes the following components by weight: 55-80 parts of polypropylene, 5-20 parts of filler, 1-5 parts of special fiber, 15-20 parts of toughening agent, 0.1-0.5 parts of mixed compatibilizer, and 0-1.2 parts of auxiliary agent; The polypropylene is a binary block copolymer polypropylene synthesized from ethylene and propylene; The special fiber is an ultra-high molecular weight polyethylene fiber with a fiber fineness of 400 to 800 deniers; The mixed compatibilizer includes polyethylene grafted maleic anhydride and polypropylene grafted maleic anhydride.

2. The low-temperature explosion polypropylene composite material according to claim 1, characterized in that: The mass ratio of the polyethylene grafted maleic anhydride to the polypropylene grafted maleic anhydride is 1:3 to 3:

1.

3. The low-temperature explosion polypropylene composite material according to claim 1, characterized in that: In the polyethylene grafted with maleic anhydride and the polypropylene grafted with maleic anhydride, the grafting rate of maleic anhydride is 0.5-1.6%.

4. The low-temperature explosion polypropylene composite material according to claim 1, characterized in that: The filler is selected from one or more of basic magnesium sulfate whiskers, talcum powder, and calcium carbonate; the filler D 50 The particle size is 0.5~12μm.

5. The low-temperature explosion polypropylene composite material according to claim 4, characterized in that: The D of the talc 50 The particle size is 0.65~1μm.

6. The low-temperature explosion polypropylene composite material according to claim 4, characterized in that: The D of calcium carbonate 50 The particle size is 4 to 8 μm.

7. The low-temperature explosion polypropylene composite material according to claim 1, characterized in that: The toughening agent is selected from one or both of ethylene-octene random copolymer and ethylene-octene block copolymer.

8. The low-temperature explosion polypropylene composite material according to claim 1, characterized in that: The auxiliary agent is selected from one or more of lubricants, antioxidants, and light stabilizers.

9. The method for preparing the low-temperature explosion polypropylene composite material according to any one of claims 1 to 8, characterized in that: The low-temperature explosion polypropylene composite material is prepared by mixing polypropylene, special fiber, toughening agent, mixed compatibilizer and auxiliary agent, adding filler and mixing, and then melt-extruding.

10. Use of the low-temperature explosion polypropylene composite material according to any one of claims 1 to 8 in the automobile industry.

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