Polypropylene composite modified with branched polyolefin material and method for its production

Abstract

The application discloses a branched polyolefin material modified polypropylene composite material, which comprises the following components in parts by weight: high-melt-index polypropylene 10-40 parts, low-melt-index impact polypropylene 30-50 parts, branched polyolefin material 10-35 parts, and filler 15-25 parts. The branched polyolefin material has long and short branched chain structures, a weight average molecular weight of 2000-8000000 g / mol, a branching degree of 40-180 / 1000C, and a melt index of 0.01-20 g / 10 min under the condition of 190 DEG C and a load of 2.16 kg. The application adopts light olefin raw materials, solves the technical problem that the mechanical properties of ethylene-butene copolymer as an elastomer are not as good as those of ethylene-octene copolymer by optimizing the molecular structure and combination of the material, and compared with traditional POE ethylene-octene copolymer, the light olefin is used as the raw material to reduce the raw material cost, improve economic benefits, significantly improve the low-temperature toughness and mechanical properties of the polypropylene composite material, and is especially suitable for the plastic modification field.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials and their molding and processing, and in particular relates to a branched polyolefin toughened and modified polypropylene composite material, its preparation method and application. Background Technology

[0002] Polypropylene (PP) materials possess excellent mechanical properties and chemical stability, along with advantages such as high heat resistance, low price, abundant raw material sources, and ease of processing, making them widely used in the automotive, aerospace, home appliance, pharmaceutical, and petrochemical industries. However, ordinary PP materials often exhibit poor impact toughness, particularly at low temperatures, leading to significant brittleness. This limits the large-scale application of PP, necessitating toughening modifications. Currently, the most commonly used elastomers for toughening PP include EPR (ethylene propylene rubber), EPDM (ethylene propylene diene monomer rubber), SBS (styrene-butadiene-styrene block copolymer), and POE (polyolefin elastomer). PP / POE is an elastomer-based toughening system for PP developed in recent years, offering the best toughening effect, good weather resistance, excellent flowability, good thermal stability, and good processability. It is currently the most commonly used elastomer-based toughening system for PP. POE exhibits excellent compatibility with PP, and its toughening effect, especially at low temperatures, is significantly superior to EPDM and EPR. Currently, in the field of plastic modification, POE has gradually replaced EPDM and become the mainstream toughening modifier.

[0003] POE is a copolymer synthesized by random copolymerization of ethylene and 1-butene or 1-octene, with the 1-butene or 1-octene content ranging from 15% to 45% (generally >20%) and a crystallinity of less than 25%. POE obtained by copolymerizing ethylene and 1-octene (C8-POE) typically exhibits superior mechanical properties compared to POE obtained by copolymerizing ethylene and 1-butene (C4-POE). However, due to the significantly higher difficulty in obtaining 1-octene compared to 1-butene, 1-octene production capacity is lower and its price is much higher than that of 1-butene, resulting in a much higher price for C8-POE compared to C4-POE. The presence of short branches significantly improves impact strength; however, because POE is synthesized using metallocene catalysts, its molecular weight distribution is typically narrow, leading to significant pseudoplasticity and significant shear thinning at higher screw speeds. This results in poor processing stability and a higher defect rate in the molded product. Furthermore, short branches do not offer advantages in filler dispersion and loading limits, hindering the improvement of overall product performance.

[0004] Over 80% of the materials used in automotive front and rear bumpers are modified polypropylene (PP). This modified PP must possess good impact resistance, weather resistance, formability, toughness, and paint adhesion. After PP is toughened with elastomers, the resulting polypropylene composites typically exhibit good toughness at room temperature, with cantilever beam notched impact strength reaching 40–100 KJ / m². 2 However, its toughness decreases significantly at low temperatures (-30℃), typically only reaching 3–10 KJ / m. 2 The temperature drops by an order of magnitude. In cold environments, bumper materials become brittle and their toughness decreases, making them prone to breakage upon impact, forming sharp fracture surfaces that can cause secondary injuries to pedestrians. Therefore, it is necessary to improve the toughness of POE and obtain modified polypropylene composite materials with excellent overall performance while reducing costs. In particular, it is necessary to further improve low-temperature toughness and enhance the impact resistance of automotive bumpers in low-temperature environments. Summary of the Invention

[0005] In view of this, the present invention aims to overcome the defects and deficiencies in the prior art, and proposes a branched polyolefin modified polypropylene composite material and its preparation method, as well as its application in the field of automotive bumpers.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A branched polyolefin-modified polypropylene composite material, comprising the following components in parts by weight:

[0008] 10-40 parts of high melt index polypropylene

[0009] 30-50 parts of low melt index impact-resistant polypropylene

[0010] 10-35 parts of branched polyolefin material

[0011] 15-25 parts of filler

[0012] The low melt index impact-resistant polypropylene has a melt index of 10-20 g / 10 min under test conditions of 230℃ and 2.16 kg load; the high melt index polypropylene has a melt index of 50-80 g / 10 min under test conditions of 230℃ and 2.16 kg load.

[0013] The branched polyolefin material has a long and short branched chain structure, a weight-average molecular weight of 2000-8000000 g / mol, a branching degree of 40-180 / 1000°C, and a melt index of 0.01-20 g / 10 min at 190°C and a load of 2.16 kg.

[0014] Preferred branched polyolefin modified polypropylene composite materials, comprising the following components in parts by weight:

[0015] 26-30 parts of high melt index polypropylene

[0016] 45-50 parts of low melt index impact-resistant polypropylene

[0017] 16-35 parts of branched polyolefin material

[0018] 15-25 parts of filler.

[0019] Furthermore, the branched polyolefin material is one or more combinations of branched structural materials obtained by solution polymerization of ethylene or ethylene and C3-C5 olefins as raw materials. Preferably, the branched polyolefin material is a single ethylene branched polymerization product. The branched polyolefin material can be in the form of an elastomer, rubber, oil, or wax.

[0020] Furthermore, the branched polyolefin material preferably has a weight-average molecular weight of 50,000 to 500,000 g / mol, a branching degree of 55 to 120 / 1000°C, and a melt index of 0.5 to 15 g / 10 min at 190°C and a load of 2.16 kg.

[0021] Furthermore, the melting point of the main component of the branched polyolefin material is -20℃ to 90℃, preferably 20℃ to 80℃; the crystallinity is 0 to 15%, preferably 0.1% to 15%.

[0022] In this invention, the branched polyolefin material can be prepared by the following method:

[0023] Organic solvent, catalyst, and co-catalyst are added to a reactor, the temperature is controlled at 10-100℃, ethylene is introduced into the reactor to carry out a polymerization reaction, the ethylene pressure is 0.1-5MPa, the reaction time is 10-90min, after the reaction is completed, the reaction solution is added to acidified ethanol to terminate the reaction and a solid precipitate is obtained. After washing and drying the solid precipitate, branched polyolefin material is obtained.

[0024] The catalyst is a post-transition metal catalyst;

[0025] The post-transition metal catalyst is a metal complex olefin polymerization catalyst with post-transition metal atoms such as nickel(II), palladium(II), iron(II), cobalt(II), and ruthenium(II) as the active center. The chelating ligand is selected from types such as N^N, P^N, N^O, and P^O. Various post-transition metal catalysts disclosed in the prior art that can catalyze the polymerization of ethylene to prepare branched polyolefins and can obtain the branched polyolefin material parameters specified in this invention are all applicable to this invention.

[0026] Furthermore, the post-transition metal catalyst is a Brookhart catalyst; such as a (α-diimine) nickel / palladium complex; more preferably, an α-diimine nickel catalyst.

[0027] The co-catalyst is one or more of diethylaluminum chloride, diethylaluminum chloride, methylaluminoxane, polymethylaluminoxane, and sesquiethylaluminum chloride (EASC), preferably sesquiethylaluminum chloride.

[0028] The molar ratio of Al in the co-catalyst to Ni in the α-diimine nickel catalyst is 50–1000:1.

[0029] The polymerization reaction is carried out in an organic solvent, which is one or more of dichloromethane, toluene, and n-hexane.

[0030] The preferred polymerization reaction temperature is 20–80℃, and the reaction pressure is 0.5–3 MPa.

[0031] In this invention, a branched structure with tunable long and short branch structures is obtained through long-chain branching polymerization in solution using a post-transition metal catalyst. Since this invention involves in-situ polymerization of ethylene, the branches contain both long and short chains, resulting in high branching degree. The long branches also increase the crosslinking points, leading to lower crystallinity and improved elastomer properties.

[0032] Furthermore, the filler is talc powder with a particle size of 0.01 to 0.1 μm or glass fiber with a particle size of 0.1 to 10 mm.

[0033] Furthermore, the branched polyolefin-modified polypropylene composite material may also include antioxidants and lubricants, wherein the branched polyolefin-modified polypropylene composite material comprises the following components in parts by weight:

[0034] 10-40 parts of high melt index polypropylene

[0035] Low melt index polypropylene 30-50 parts

[0036] 10-35 parts of branched polyolefin material

[0037] 15-25 parts of filler

[0038] Antioxidant 0.1 to 0.5 parts

[0039] Lubricant 0.1 to 0.5 parts.

[0040] Preferably, the antioxidant is any one or a mixture of two of phenolic and phosphite antioxidants.

[0041] Preferably, the lubricant is any one or a mixture of silicone-based, ester-based, amide-based, polyethylene-based, and fatty acid-based lubricants.

[0042] This invention also provides a method for preparing the branched polyolefin-modified polypropylene composite material, the method comprising:

[0043] After the raw materials are mixed evenly according to the formula ratio, they are added to the feed port of a twin-screw extruder, or a twin-screw extruder with a separate metering system is used to continuously feed the components into the feed port of the extruder according to the formula ratio. The mixture is then melt-granulated at a temperature of 180-250°C to obtain the branched polyolefin material modified polypropylene composite material.

[0044] Furthermore, the twin-screw extruder has a length-to-diameter ratio of (30-50):1, a processing temperature of 180-250℃, a screw speed of 300-600rpm, and a feed rate of 300-900kg / h.

[0045] Melt granulation can be performed using a typical extrusion process with the following parameters: conveying section temperature 90–140°C, melting section temperature 180–250°C (preferably 180–230°C), homogenization section temperature 180–250°C (preferably 200–220°C), die temperature 180–250°C (preferably 200–220°C), and screw speed 100–200 rpm.

[0046] In this invention, the branching degree of branched polyolefin materials is increased, and different branch types and lengths are combined. The materials have special molecular chain entanglement structures and rheological properties, as well as a lower glass transition temperature. The toughening effect is significantly improved compared with conventional elastomers or rubbers, and the room temperature and low temperature notched impact strength of polypropylene composite materials are greatly improved.

[0047] The present invention also provides the application of the branched polyolefin material-modified polypropylene composite material in the preparation of automobile bumpers.

[0048] The present invention also provides a polypropylene composite material for automobile bumpers, wherein the polypropylene composite material for automobile bumpers is a polypropylene composite material modified with branched polyolefin material.

[0049] Compared with existing technologies, the present invention has the following advantages:

[0050] This invention adds branched polyolefin materials with long and short branched chain structures as toughening agents, which can effectively improve the toughening efficiency of the matrix and the filler loading effect, while maintaining good processing stability of the composite material and reducing the defect rate.

[0051] This invention uses light olefin raw materials and solves the technical problem that the mechanical properties of ethylene-butene copolymer as an elastomer are inferior to those of ethylene-octene copolymer by optimizing the molecular structure and combination of materials. Compared with traditional POE ethylene-octene copolymer, using light olefin as raw material reduces raw material costs and improves economic efficiency.

[0052] This invention significantly improves the low-temperature toughness of polypropylene composite materials, and significantly enhances their impact resistance at -30℃. When used as a bumper material, it is less prone to breakage in low-temperature environments, thus improving the vehicle's impact safety at low temperatures.

[0053] This invention uses a blend of low melt flow index (MFI) and high melt flow index (HFI) polypropylene. High melt flow index polypropylene has good flowability, which is beneficial for injection molding production and represents an optimization direction for polypropylene composites. However, a high melt flow index also means a lower molecular weight of polypropylene, making it difficult to improve its modulus and notched impact strength. This invention uses a blend of low melt flow index and high melt flow index polypropylene to improve impact resistance, while the high melt flow index polypropylene maintains flowability. Simultaneously, talc powder and / or glass fiber of a specific size are added to synergize with the branched polyolefin material. The branched polyolefin material of this invention has a high melt flow index and good flowability, which helps improve compatibility with polypropylene. Furthermore, the filler is more easily and evenly dispersed in the polypropylene, facilitating its reinforcing effect. Therefore, the mechanical properties of the polypropylene composite material of this invention are significantly improved, making it particularly suitable for plastic modification applications. Detailed Implementation

[0054] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which this invention pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0055] The invention will be described in detail below with reference to specific embodiments.

[0056] Example 1

[0057] In 100 mL of n-hexane solvent, α-diimine nickel catalyst (2 μmol) and sesquiethyl aluminum chloride (2 mmol, Al:Ni molar ratio = 1000) were added. The temperature was controlled at 20–80 °C, and ethylene was introduced to carry out the polymerization reaction. Timing was started after the ethylene pressure stabilized. The ethylene pressure was 0.1–5 MPa, and the reaction time was 10–70 min. After the reaction was completed, the reaction solution was added to 200 mL of acidified ethanol, stirred for 10 h, filtered, washed with ethanol, and vacuum dried to obtain the branched polyolefin material.

[0058] The α-diimine nickel catalyst used in this embodiment was prepared according to the following reaction formula:

[0059]

[0060] In Formula I, R1 is a phenyl or a substituted phenyl, wherein the substituted phenyl is p-aminophenyl, p-methylphenyl, p-methoxyphenyl or p-tert-butylphenyl;

[0061] R2 is a phenyl or a substituted phenyl, wherein the substituted phenyl is p-methylphenyl, p-methoxyphenyl, p-fluorophenyl or p-tert-butylphenyl;

[0062] R3 is a phenyl or a substituted phenyl, wherein the substituted phenyl is p-methoxyphenyl, p-fluorophenyl or p-tert-butylphenyl;

[0063] In toluene solvent, aniline compounds of formula II and dimethyl ethyl ketone are mixed at a molar ratio of 2–2.2:1 and reacted at 60–90 °C for 20–24 hours under the catalytic action of p-toluenesulfonic acid. Then, water is separated and refluxed for 2–3 days using a water separator to obtain the diimine ligand compound of formula III.

[0064] The diimine ligand compound shown in Formula III and (DME)NiBr2 were mixed at a molar ratio of 1:0.5 to 2, dissolved in dichloroethane solvent, and stirred under nitrogen protection for 10 to 24 hours to prepare the α-diimine nickel catalyst shown in Formula I.

[0065] In this embodiment, R1, R2, and R3 are all α-diimine nickel catalysts for the preparation of p-tert-butylphenyl, and the specific method is as follows:

[0066] 2,4-Bis(p-tert-butylphenyl)-6-di-tert-butylphenylmethylaniline (4 mmol) and dimethylbutane (2 mmol) were dissolved in 100 mL of toluene, and 10 mg of p-toluenesulfonic acid (PTSA) was added. The mixture was stirred and refluxed at 80 °C for 24 h. The mixture was then refluxed for 3 days using a Dean-Stark water separator. After cooling the reaction solution to room temperature, part of the solvent was evaporated under reduced pressure, precipitating a solid. 400 mL of methanol was added to precipitate the solid product. The product was filtered, and the filter cake was washed with methanol and dried to obtain the diimine ligand compound in 81% yield.

[0067] Under nitrogen protection, a mixture of diimine ligand compound and (DME)NiBr2 (0.2 mmol) and a diimine ligand compound (0.20 mmol) was dissolved in 5 mL of dichloromethane. The mixture was stirred at room temperature for 20 h. After removing the dichloromethane under reduced pressure, diethyl ether was added, and a red solid precipitated. The solid was filtered, washed with diethyl ether, and dried to obtain the α-diimine nickel catalyst. The yield was approximately 85%.

[0068] Using ethylene as raw material, n-hexane as solvent, α-diimide nickel catalyst as catalyst, and sesquiethylaluminum chloride as co-catalyst, branched structural material B1 (reaction temperature 30℃, pressure 0.4MPa, melt index 1.2g / 10min, molecular weight 130,000, branching degree 45 / 1000C, crystallinity 15%, melting point 75℃) and branched structural material B2 (reaction temperature 45℃, pressure 0.5MPa, melt index 10g / 10min) were prepared by adjusting the ratio of main and co-catalysts, process, and product compounding combination. n, molecular weight 180,000, branching degree 65 / 1000C, melting point 63℃, crystallinity 8%), branched structural material B3 (melt index 5g / 10min, molecular weight 250,000, branching degree 80 / 1000C, melting point 60℃, crystallinity 4%, reaction temperature 50℃, pressure 0.6MPa), branched structural material B4 (reaction temperature 70℃, pressure 2.5MPa, melt index 1g / 10min, molecular weight 450,000, melting point 20℃, branching degree 120 / 1000C, crystallinity 0.2%).

[0069] Using ethylene and octene as raw materials, alkanes as solvents, and transition metal complex catalysts, branched elastomer B5 (melt index 1.1 g / 10 min, molecular weight 200,000, branching degree 40 / 1000C, crystallinity 18%, melting point 60℃) was prepared.

[0070] Branched structural materials B1, B2, B3, B4, and branched structural elastomer B5 were used to prepare polypropylene composite materials. The specific steps are as follows:

[0071] 45 kg of low melt flow index polypropylene (MFR = 18 g / 10 min), 26 kg of high melt flow index polypropylene (MFR = 53 g / 10 min), 16 kg of branched polyolefin (branched structural material B1 for Experiment 1, branched structural material B2 for Experiment 2, branched structural material B3 for Experiment 3, branched structural material B4 for Experiment 4, and branched structural elastomer B5 for Experiment 5), 15 kg of talc CX3000 (particle size 0.03 μm), 0.3 kg of antioxidant 1010, 0.2 kg of antioxidant 168, 0.2 kg of zinc stearate, and 0.1 kg of lubricant TR451 were melt extruded using a twin-screw extruder with a length-to-diameter ratio of 40:1. The extrusion conditions were: conveyor section temperature 100℃, melting section temperature 210℃, homogenization section temperature 210℃, die temperature 210℃, and screw speed 120 rpm.

[0072] The physical and mechanical properties of polypropylene composites obtained using five different elastic moduli are shown in Table 1.

[0073] Table 1

[0074]

[0075]

[0076] Experimental results show that the branched structure material B1 in Experiment 1 has a branching degree of only 45 / 1000C, a low melt index, and a low molecular weight. Although its strength, modulus, and impact strength are good, its low-temperature impact resistance is poor.

[0077] The elastomer in Experiment 5 was an ethylene-octene copolymer, which had the lowest degree of branching among the four elastomers. However, in terms of mechanical properties, it was better than that in Experiment 1, and its impact strength was significantly improved compared to Experiment 1. This may be because octene has long chains, and the long branches form a coiled structure, which improves the toughness and impact resistance of polypropylene. However, the long branches also lead to a decrease in melt index, which is not conducive to industrial applications.

[0078] Although the elastomer in Experiment 5 has a lower degree of branching, its overall performance is superior to that of the ethylene-branched material in Experiment 1.

[0079] However, experiments 2, 3, and 4, without using octene as a raw material, significantly improved the low-temperature impact resistance by increasing the branching degree of the ethylene copolymer, using a branched structure with a branching degree of 55–120 / 1000°C. Furthermore, the mechanical properties at room temperature were also significantly improved compared to experiments 1 and 5, meeting the standard requirements for polypropylene used in bumpers. The melt index of the polypropylene composite material prepared by this invention is greater than 15 g / 10 min, meeting injection molding requirements. Moreover, the raw material used in experiments 2, 3, and 4 is the light olefin ethylene, which is inexpensive and more cost-effective than the octene raw material used in experiment 5.

[0080] Example 2

[0081] Branched structural materials B1, B2, B3, B4, and B5 were used to prepare polypropylene composite materials, and the specific steps are as follows:

[0082] 50 kg of low melt flow index polypropylene (MFR = 15 g / 10 min), 30 kg of high melt flow index polypropylene (MFR = 65 g / 10 min), 20 kg of branched polyolefin (branched structural material B1 for Experiment 6, branched structural material B2 for Experiment 7, branched structural material B3 for Experiment 8, branched structural material B4 for Experiment 9, and branched structural elastomer B5 for Experiment 10), 20 kg of glass fiber (length 1–5 mm, aspect ratio 150), 0.3 kg of antioxidant 1010, 0.2 kg of antioxidant 168, 0.2 kg of zinc stearate, and 0.1 kg of lubricant TR451 were melt-extruded using a twin-screw extruder with an aspect ratio of 40:1. The extrusion conditions were: conveyor section temperature 100℃, melting section temperature 210℃, homogenization section temperature 210℃, die temperature 210℃, and screw speed 120 rpm.

[0083] The physical and mechanical properties of polypropylene composites obtained using five different elastic moduli are shown in Table 2.

[0084] Table 2

[0085]

[0086] Experiments 6-10 used glass fiber as the filler. Compared to talc, glass fiber can further improve strength, while slightly reducing the melt index. A comparison between experiments 6-10 shows that increased branching degree improves low-temperature toughness and significantly enhances impact resistance.

[0087] Example 3

[0088] The ingredients and preparation process were the same as in Example 1, according to the formula in Table 3.

[0089] Table 3. Composition formulas (kg) for comparative examples and implementation examples

[0090]

[0091]

[0092] The physical and mechanical properties of the polypropylene composites tested in Experiments 11–14 are shown in Table 4.

[0093] Table 4

[0094]

[0095] In this invention, low melt flow index (MFI) impact-resistant polypropylene and high melt flow index (MFI) polypropylene are blended in a certain proportion. The low MFI impact-resistant polypropylene is used to improve impact resistance, while the high MFI maintains flowability. The combination of toughening agents with controlled molecular structure improves filler loading dispersion and mechanical properties. In Experiment 12, the excessively low amount of high MFI PP resulted in a significant decrease in the melt flow index. Furthermore, the low amount of high MFI PP led to poor overall flowability of the mixture, resulting in uneven dispersion of talc and elastomer, and a decrease in strength and impact resistance.

[0096] In Experiment 13, the amount of low melt index PP was too low. Although the melt index increased, the impact resistance decreased significantly, and the toughness of the composite material was poor.

[0097] In Experiment 14, the amount of elastomer used was only 10 kg. Generally, too little elastomer will lead to a significant decrease in low-temperature toughness. However, the data from Experiment 14 show that the low-temperature toughness decreased somewhat, but still reached 10 KJ / m. 2 As can be seen from the above, the branched elastomer of the present invention has a high toughening efficiency and can achieve a good toughening effect even with a small amount.

[0098] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A branched polyolefin material modified polypropylene composite, characterized in that The polypropylene composite material comprises the following components by weight: high melt index polypropylene 10-40 parts low melt index impact polypropylene 30-50 parts branched polyolefin material 10-35 parts filler 15-25 parts The low melt index impact polypropylene has a melt index of 15-20 g / 10 min under the test conditions of 230℃ and a load of 2.16 kg; the high melt index polypropylene has a melt index of 50-80 g / 10 min under the test conditions of 230℃ and a load of 2.16 kg; The branched polyolefin material is a branched structure material prepared by a solution polymerization method using ethylene as a raw material; the branched polyolefin material has long and short chain structures, a weight average molecular weight of 50000-500000 g / mol, a branching degree of 65-80 / 1000 C, and a melt index of 5-10 g / 10 min under the test conditions of 190℃ and a load of 2.16 kg; The polypropylene composite material has a melt index greater than 15 g / 10 min; The filler is talc powder with a particle size of 0.01-0.1 μm or glass fiber with a length of 0.1-10 mm.

2. The polypropylene composite of claim 1, wherein The main component of the branched polyolefin material has a melting point of -20℃-90℃ and a crystallinity of 0-15%.

3. The polypropylene composite of claim 1, wherein The branched polyolefin material-modified polypropylene composite material further comprises an antioxidant and a lubricant, and comprises the following components by mass: high melt index polypropylene 10-40 parts low melt index impact polypropylene 30-50 parts branched polyolefin material 10-35 parts filler 15-25 parts antioxidant 0.1-0.5 parts lubricant 0.1-0.5 parts.

4. The polypropylene composite of claim 3, wherein The antioxidant is any one or a mixture of two of phenolic antioxidants and phosphite antioxidants; the lubricant is any one or a mixture of multiple of silicone lubricants, ester lubricants, amide lubricants, polyethylene lubricants, and fatty acid lubricants.

5. Process for the preparation of a branched polyolefin material modified polypropylene composite according to any one of claims 1 to 4, characterized in that The method is: After the raw materials are uniformly mixed according to the formula, they are fed into the feeding port of a double-screw extruder, or a double-screw extruder with a separate metering system is used to continuously feed the components into the feeding port of the extruder according to the formula, and the branched polyolefin material-modified polypropylene composite material is prepared by melt granulation at a temperature of 180-250℃.

6. Use of the branched polyolefin material-modified polypropylene composite material according to any one of claims 1-4 in the preparation of an automobile bumper.

Images