Lightweight PP modified material for automobile bumpers

Abstract

The invention discloses a lightweight PP modified material for an automobile bumper. The modified material is prepared from the following raw materials in parts by mass: 80-120 parts of a resin raw material; 5-20 parts of a filling agent; 10 to 25 parts of a toughening agent; 0.5 to 4 parts of a lubricant; 0.4 to 2 parts of an antioxidant; 0.3 to 1.5 parts of a cross-linking agent; the resin raw material is a recycled PP T30S polypropylene resin reworked material subjected to acid pickling treatment, and the filling agent is calcium carbonate with the particle size of 0.1-0.5 mu m; the modified material is prepared by mixing a resin raw material with other auxiliaries in proportion and then adding the mixture into a twin-screw extruder for extrusion granulation. The light-weight PP modified material for the automobile bumper is prepared by recovering and regenerating the polypropylene raw material through specific processing and modification processes, has the advantages of impact resistance, low temperature resistance, chemical resistance, light weight, recyclability and the like, and not only ensures the material performance, but also improves the production efficiency by recovering and regenerating the polypropylene raw material and combining with a modification processing flow. And the cost is effectively reduced, and the green and environment-friendly development concept is embodied.

Description

Technical Field

[0001] The invention relates to the technical field of automobile parts materials, in particular to a lightweight PP modified material for automobile bumpers. Background Art

[0002] Polypropylene (PP) is a semi-crystalline thermoplastic polymer with high impact resistance and mechanical strength, as well as good corrosion resistance to a variety of organic solvents and acids and alkalis. This material is widely used in the industrial field and is a leader among many polymer materials. At present, more and more automotive parts use PP as the main material, including reinforced PP for instrument panels, steering wheels, handles, containers, battery shells and other parts, and toughened PP for bumpers and wheel covers.

[0003] As a key component of the vehicle exterior, the car bumper plays multiple roles such as safety, function and decoration, and has a significant impact on the safety performance and appearance design of the car. The material of the ideal bumper usually needs to have good performance and good processing characteristics, while being economical in price.

[0004] Correspondingly, in terms of performance, polypropylene can be used normally at a temperature of 100°C, exhibiting good thermal stability and mechanical properties, good chemical stability, and is not affected by humidity. It can remain stable in harsh environments and road conditions, thereby improving the durability and service life of the vehicle.

[0005] In terms of processing, compared with metal, modified PP plastic materials are easier to process into various shapes and structures, providing designers with greater design freedom. PP plastic materials for bumpers have good fluidity, and even complex designs can be easily realized, allowing each car to have a unique appearance.

[0006] In terms of price, polypropylene has a wide range of raw materials, including petroleum, coal, methanol, propylene, etc. In addition, its easy processing and simple production process make its production cost much lower than other plastic materials. Therefore, PP materials have obvious advantages in terms of cost performance.

[0007] However, although PP material has excellent performance, its low temperature performance and impact resistance are relatively weak, its wear resistance is insufficient, it is easy to age, and its dimensional stability needs to be improved. Therefore, in the production of automobile bumpers, modified PP is usually used as the material. Modified polypropylene refers to adding one or more other substances to the polypropylene resin to change its original properties and improve the performance in specific aspects, thereby expanding its application range. At present, modified PP materials dedicated to automobile bumpers are usually made of PP as the main material, and rubber or elastomers, inorganic fillers, masterbatches, additives, etc. are added and processed by mixing. When producing high-performance modified PP automobile bumpers, special modifiers and toughening agents are added to improve the performance of the material. For example, adding an appropriate amount of elastomer can enhance the impact resistance and crack resistance of the material, while heat stabilizers can improve the heat resistance and aging resistance of the material.

[0008] At the same time, with the rapid development of the automobile industry and the improvement of global environmental awareness, new energy vehicles have gradually become the mainstream of the market. In the design and manufacture of new energy vehicles, energy saving, environmental protection and safety have become the focus of attention, and lightweight, comfort and green concepts have become the main direction of the development of the automobile industry. New energy vehicles focus on improving energy efficiency and cruising range, and lightweighting of automotive materials is one of the important ways to achieve this goal. Automobile lightweighting technology can reduce the weight of the car body and reduce fuel consumption, and is one of the key measures to achieve energy conservation and emission reduction. Under this trend, all parts of the car are being designed to be lightweight. At present, automobile parts are more and more using plastic materials to replace bulky and expensive metal components. For example, the existing public patents such as CN103030893B provide a modified polypropylene composite material and a preparation method thereof. A high-impact, low-density, low-shrinkage modified polypropylene composite material and a preparation method thereof are provided. The modified polypropylene composite material obtained by the method has the advantages of high impact, low density and low shrinkage, and replacing the existing automobile bumper material is in line with the trend of automobile lightweight development.

[0009] However, most of the existing technologies focus on the lightweight advantages brought by polypropylene materials, while ignoring the white pollution environmental problems that may be caused by the large-scale application of plastics, which is contrary to its original intention of being green and environmentally friendly. In fact, polypropylene materials can not only be recycled and reused after proper treatment, but also the material cost can be further reduced through appropriate processing procedures. Modified polypropylene materials need to undergo a series of modification and processing during the production process. Therefore, how to combine recycled polypropylene materials with appropriate modification and processing procedures to further reduce costs and promote green and environmentally friendly concepts still needs in-depth research. In view of this, in-depth research was conducted on the above issues, resulting in this case. Summary of the invention

[0010] The purpose of the present invention is to provide a lightweight PP modified material for automobile bumpers to solve the problem of how to combine recycled polypropylene materials with appropriate modification treatment processes in the above background technology to further reduce costs and promote green and environmentally friendly concepts.

[0011] To achieve the above object, the present invention provides the following technical solution: a lightweight PP modified material for automobile bumper, the modified material is composed of the following raw materials by mass: 80-120 parts of resin raw material; 5-20 parts of filler; 10-25 parts of toughening agent; 0.5-4 parts of lubricant; 0.4-2 parts of antioxidant; 0.3-1.5 parts of cross-linking agent; The resin raw material is recycled PP T30S polypropylene resin after acid washing, and the filler is calcium carbonate with a particle size of 0.1 to 0.5 μm; The modified material is prepared by mixing the resin raw material with other additives in proportion and then adding the mixture into a twin-screw extruder for extrusion granulation, which specifically includes the following steps: Step (1) Recycled material treatment: The recycled PP T30S polypropylene resin is initially washed with water and then crushed into particles with a diameter of 1 to 2 mm. The crushed particles are then washed again with ethanol solution, dried, and then soaked in a hydrochloric acid solution with a mass concentration of 36% to 40% for 20 to 30 minutes. Finally, the recycled PP material is washed again for standby use. Step (2) mixing the raw materials uniformly: firstly disperse the filler in water, mix the PP recycled material obtained in step (1) and control the temperature to 70-90°C and stir for 3-5 minutes, then add the toughening agent, antioxidant, cross-linking agent and lubricant, mix and continue to heat and stir for 30-60 minutes to obtain a mixed raw material; Step (3) Mixing, extrusion and granulation: Add the mixed raw materials obtained in step (2) into a twin-screw extruder for extrusion and granulation, control the temperature of each zone to be 190-240° C., the residence time to be 5-8 min, and the twin-screw speed to be 300-350 r / min, to obtain PP material for automobile bumper.

[0012] Preferably, the modified material is composed of the following raw materials in parts by mass: 100 parts of resin raw material; Filler 12 parts; 20 parts of toughening agent; 2 parts of lubricant; 1.2 parts of antioxidant; 0.8 parts of crosslinking agent.

[0013] Preferably, the resin raw material accounts for 73.5% by weight of the modified material raw material, and the acid washing of the recycled resin raw material uses a concentrated hydrochloric acid solution with a mass concentration of 38% to 40% to corrode the surface of the recycled PP material, so that tiny holes and pore structures appear on it for loading the filler.

[0014] The above technical solution is adopted to clean the recycled PP recycled material with ethanol solution to remove impurities such as surface oil, and then corrode the surface with hydrochloric acid solution to make it rough and have tiny holes, which is convenient for filler loading. The calcium carbonate filler has a small particle size and good dispersibility, which can enhance the heat resistance, bending strength and toughness of recycled PP plastics and improve the performance of products. PP recycled material is a material for processing recycled polypropylene products. The toughening agent has good compatibility with PP recycled material. With the lubricant, it helps to mix the filler evenly, improve the impact strength of the system, and has good toughness, impact resistance and fluidity.

[0015] Preferably, the filler accounts for 8.8% by weight of the modified material raw material, and the particle size of calcium carbonate used as the filler is 0.1-0.2 μm, and the whiteness of calcium carbonate is ≥ 90% to replace the white pigment to achieve whitening effect.

[0016] By adopting the above technical scheme, calcium carbonate CaCO3 is white, non-toxic, odorless and non-irritating, and can act as a skeleton in plastic products to improve stability. Small-particle calcium carbonate has good dispersibility and good compatibility with plastics and resins. It can be loaded on the surface of PP recycled materials after pickling, enhance the performance of PP recycled materials, and improve hardness, gloss and flatness. At the same time, calcium carbonate has high whiteness and can whiten, and can replace whitening agents to further reduce costs.

[0017] Preferably, the toughening agent accounts for 14.7% by weight of the modified material raw material, the toughening agent is POE 8200 polyolefin elastomer, and the toughening agent also includes adding mineral fiber for further reinforcement. In step (3), the mineral fiber is added to the twin-screw extruder by the weight loss method, and the mineral fiber is one or more of glass fiber, silica whisker or aluminum borate whisker.

[0018] Using the above technical solution, POE is a thermoplastic elastomer with narrow molecular weight distribution and uniform short chain branches. It has low cohesive energy, shear sensitivity, good compatibility with PP, and the temperature dependence of shear viscosity is close to that of PP, with significant toughening effect. At the same time, it has good resilience, flexibility, low hardness and cold resistance. After toughening PP, it can improve the impact strength and improve the comprehensive performance of the material. Combining with mineral fiber for further reinforcement helps to reduce permanent deformation and enhance mechanical properties.

[0019] Preferably, the antioxidant is a mixture of one or more of antioxidant DLTP, antioxidant 168 or antioxidant 1010.

[0020] By adopting the above technical solution, the antioxidant has good compatibility with most polymers and has a significant antioxidant effect on polypropylene and polyethylene. The antioxidant protects the product from high-temperature oxidation, ensures product performance, delays aging, and extends the service life. It is also a highly efficient processing stabilizer to prevent high-temperature oxidation during product processing.

[0021] Preferably, the cross-linking agent is a bifunctional compound bismaleimide BMI with maleimide MI as an active end group.

[0022] By adopting the above technical solution, bismaleimide has good radiation resistance, flame retardancy, good mechanical properties and stability, and the molding process is similar to epoxy resin, so it is widely used in resin matrix of composite materials, high temperature resistant insulation materials and adhesives, etc. It effectively improves the main properties of modified materials.

[0023] Preferably, the lubricant is one or more of polyethylene wax, calcium stearate, zinc stearate, and stearic acid amide, which are used to improve the fluidity of the product during extrusion molding.

[0024] By adopting the above technical scheme, the lubricant has the advantages of low viscosity, high softening point, good hardness, non-toxicity, good thermal stability, low volatility at high temperature, etc. It has good dispersibility for raw materials and has external and internal lubrication. It prevents the barrel from sticking during processing and inhibits friction heat generation. It improves fluidity and adhesion during extrusion molding, reduces retained materials, and improves production efficiency. It is resistant to moisture and chemicals at room temperature, has good electrical properties, and improves the appearance of the finished product.

[0025] Compared with the prior art, the invention has the following beneficial effects: the modified polypropylene plastic is prepared by recycling recycled polypropylene raw materials through specific processing and modification processes. The material has a uniform molecular structure and exhibits excellent physical properties, including high strength, high toughness and high stability. It is suitable for the production of automobile bumpers, and has good heat resistance and low-temperature impact resistance, and can adapt to changing environmental conditions. The finished product after processing exhibits excellent mechanical strength and tensile properties. Calcium carbonate, as a filler, plays a skeleton role in plastic products and enhances the stability of the material. Small-particle calcium carbonate has good dispersibility, good compatibility with plastics and resins, and can adhere to the surface of polypropylene recycled materials treated with acid washing, thereby improving its performance. In addition, the high whiteness of calcium carbonate can be used as a whitening agent, which helps to reduce costs. The polypropylene recycled material used in conjunction with a toughening agent can give the material good toughness and elasticity, and the synergistic effect of each component significantly reduces the possibility of cracking of the product and greatly improves the impact resistance. The automobile bumper manufactured using the modified material shows significant advantages in safety, lightweight and design flexibility. It not only ensures the safety and durability of the car, but the use of lightweight materials also improves fuel efficiency, reduces exhaust emissions, and meets the environmental protection and energy-saving requirements of the modern automobile manufacturing industry.

[0026] In general, the modified material has the advantages of impact resistance, low temperature resistance, chemical resistance, as well as lightweight and recyclability. By recycling the recycled polypropylene raw materials and combining them with the modified processing flow, not only the material performance is guaranteed, but also the cost is effectively reduced, reflecting the green and environmentally friendly development concept. With the continuous advancement of science and technology and people's increasing requirements for automobile safety and environmental protection, the application prospects of this modified material in the automotive industry will become increasingly broad. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram comparing the relevant performance parameters of the present invention and the existing conventional PP materials. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] See also Figure 1 , the present invention provides the following technical solutions: A lightweight PP modified material for automobile bumper, the modified material is composed of the following raw materials by mass: 100 parts of resin raw material; Filler 12 parts; 20 parts of toughening agent; 2 parts of lubricant; 1.2 parts of antioxidant; 0.8 parts of crosslinking agent.

[0030] The resin raw material is recycled PP T30S polypropylene resin after acid washing, and the filler is calcium carbonate with a particle size of 0.1 to 0.2 μm; The modified material is prepared by mixing the resin raw material with other additives in proportion and then adding the mixture into a twin-screw extruder for extrusion granulation, which specifically includes the following steps: Step (1) Recycled material treatment: The recycled PP T30S polypropylene resin is initially washed with water and then crushed into particles with a diameter of 1 to 2 mm. The crushed particles are then washed again with ethanol solution, dried, and then soaked in a hydrochloric acid solution with a mass concentration of 38% for 25 minutes. Finally, the recycled PP material is obtained after washing again for standby use. Step (2) mixing the raw materials uniformly: firstly disperse the filler in water, mix the PP recycled material obtained in step (1) and control the temperature to 80°C and stir for 4 minutes, then add the toughening agent, antioxidant, cross-linking agent and lubricant, mix and continue to heat and stir for 45 minutes to obtain a mixed raw material; Step (3) Mixing, extrusion and granulation: Add the mixed raw material obtained in step (2) into a twin-screw extruder for extrusion and granulation, control the temperature of each zone to be 220° C., the residence time to be 6 min, and the twin-screw speed to be 330 r / min, to obtain PP material for automobile bumper.

[0031] The acid washing of recycled resin raw materials uses a concentrated hydrochloric acid solution with a mass concentration of 38% to corrode the surface of the recycled PP material, causing tiny holes and pore structures to appear for the loading of fillers. The recycled PP recycled material is cleaned with an ethanol solution to remove impurities such as surface oil and dirt, and then the surface is corroded with a hydrochloric acid solution to make it rough and have tiny holes, which is convenient for the loading of fillers. The calcium carbonate filler has a small particle size and good dispersibility, which can enhance the heat resistance, bending strength and toughness of the recycled PP plastic and improve the performance of the product. PP recycled material is a material for the processing of recycled polypropylene products. The toughening agent has good compatibility with the PP recycled material. The combination of lubricants helps the filler to mix evenly, improves the impact strength of the system, and has good toughness, impact resistance and fluidity.

[0032] The particle size of calcium carbonate particles of the filler is 0.1-0.2μm, and the whiteness of calcium carbonate ≥ 90% is used to replace white pigments to achieve whitening effect. Calcium carbonate CaCO3 is white, non-toxic, odorless, and non-irritating. It can act as a skeleton in plastic products to improve stability. Small-particle calcium carbonate has good dispersibility and good compatibility with plastics and resins. It can be loaded on the surface of PP recycled materials after pickling, enhance the performance of PP recycled materials, and improve hardness, gloss and flatness. At the same time, high whiteness of calcium carbonate can whiten, and can replace whitening agents to further reduce costs.

[0033] The toughening agent is POE 8200 polyolefin elastomer, and the toughening agent also includes adding mineral fiber for further reinforcement. In step (3), the mineral fiber is added to the twin-screw extruder by the weight loss method, and the mineral fiber is glass fiber. POE is a thermoplastic elastomer with narrow molecular weight distribution and uniform short chain branches. It has low cohesive energy, shear sensitivity, good compatibility with PP, and the shear viscosity temperature dependence is close to that of PP. It has a significant toughening effect. At the same time, it has good resilience, flexibility, low hardness and cold resistance. After toughening PP, it can improve the impact strength and improve the overall performance of the material. Combining with mineral fiber for further reinforcement helps to reduce permanent deformation and enhance mechanical properties.

[0034] The antioxidant used is antioxidant 1010: pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate. The antioxidant has good compatibility with most polymers and has a significant antioxidant effect on polypropylene and polyethylene. The antioxidant protects the product from high-temperature oxidation, ensures product performance, delays aging, and extends the service life. It is also a highly efficient processing stabilizer to prevent high-temperature oxidation during product processing.

[0035] The crosslinking agent uses bismaleimide BMI, a bifunctional compound with maleimide MI as the active end group. Bismaleimide has good radiation resistance, flame retardancy, good mechanical properties and stability. Its molding process is similar to that of epoxy resin and is widely used in resin matrix of composite materials, high temperature resistant insulation materials and adhesives, etc. It effectively improves the main properties of the modified material.

[0036] The lubricant is polyethylene wax, which is used to improve the fluidity of the product during extrusion molding. The lubricant has the advantages of low viscosity, high softening point, good hardness, non-toxicity, good thermal stability, and low volatility at high temperatures. It has good dispersibility for raw materials and has external and internal lubrication. It prevents the barrel from sticking during processing and inhibits frictional heat generation. It improves fluidity and adhesion during extrusion molding, reduces retained materials, and improves production efficiency. It is moisture-resistant, chemical-resistant, and has good electrical properties at room temperature, improving the appearance of the finished product.

[0037] The performance parameters of the PP modified material obtained by this embodiment are compared with those of the conventional PP material. Figure 1 .

[0038] In actual bumper structure design application cases, for example, the front and rear bumpers are both designed with a wall thickness of 3.0mm and ordinary PP material weighs 4.5kg to 5.5kg. The heavy weight leads to an increase in deformation, structural weakness and deformation, and vibration and wind noise during driving. At the same time, under the pressure of energy conservation and emission reduction, it does not comply with the lightweight design principles and increases material cost pressure.

[0039] The PP modified material obtained by this embodiment is used to improve the melt index of the material and increase fluidity. The melt index of the current material is increased from 12g / 10min to about 24-28g / 10min; the bending modulus of the material is increased to improve rigidity. The bending modulus of the material is increased from 1200MP to 1800-2000MP; while the molding is more stable, the variable wall thickness design can be used to further reduce the dead weight, and the weight of a single piece can be reduced by 0.3-0.5kg. At the same time, the strength reduction problem caused by thinning due to changing the wall thickness design is maintained to maintain structural stability. The front and rear bumpers alone can bring about a more obvious weight reduction effect, while also saving material costs.

[0040] Contents not described in detail in this specification belong to the prior art known to professional and technical personnel in the field. Although the embodiments of the present invention have been shown and described, it is understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A lightweight PP modified material for automobile bumper, characterized in that: The modified material is composed of the following raw materials by mass: 80-120 parts of resin raw material; 5-20 parts of filler; 10-25 parts of toughening agent; 0.5-4 parts of lubricant; 0.4-2 parts of antioxidant; 0.3-1.5 parts of cross-linking agent; The resin raw material is recycled PP T30S polypropylene resin after acid washing, and the filler is calcium carbonate with a particle size of 0.1 to 0.5 μm; The modified material is prepared by mixing the resin raw material with other additives in proportion and then adding the mixture into a twin-screw extruder for extrusion granulation, which specifically includes the following steps: Step (1) Recycled material treatment: firstly recover the PP T30S polypropylene resin, wash it with water, and then crush it into particles with a diameter of 1 to 2 mm. Then, add ethanol solution to the crushed particles for re-washing. After drying, add hydrochloric acid solution with a mass concentration of 36% to 40% to soak for 20 to 30 minutes. Finally, wash it with water again to obtain PP recycled material for use. Step (2) mixing the raw materials uniformly: firstly disperse the filler in water, mix the PP recycled material obtained in step (1) and control the temperature to 70-90°C and stir for 3-5 minutes, then add the toughening agent, antioxidant, cross-linking agent and lubricant, mix and continue to heat and stir for 30-60 minutes to obtain a mixed raw material; Step (3) Mixing, extrusion and granulation: Add the mixed raw materials obtained in step (2) into a twin-screw extruder for extrusion and granulation, control the temperature of each zone to be 190-240° C., the residence time to be 5-8 min, and the twin-screw speed to be 300-350 r / min, to obtain PP material for automobile bumper.

2. The lightweight PP modified material for automobile bumper according to claim 1, characterized in that: The modified material is composed of the following raw materials by mass: 100 parts of resin raw material; Filler 12 parts; 20 parts of toughening agent; 2 parts of lubricant; 1.2 parts of antioxidant; 0.8 parts of crosslinking agent.

3. The lightweight PP modified material for automobile bumper according to claim 1, characterized in that: The resin raw material accounts for 73.5% by weight of the modified material raw material, and the acid washing of the recycled resin raw material uses a concentrated hydrochloric acid solution with a mass concentration of 38% to 40% to corrode the surface of the recycled PP material, causing tiny holes and pore structures to appear for loading the filler.

4. The lightweight PP modified material for automobile bumper according to claim 1, characterized in that: The filler accounts for 8.8% of the weight of the modified material raw material, and the particle size of calcium carbonate used as the filler is 0.1-0.2 μm, so that the filler can be loaded on the surface of the PP recycled material after pickling to enhance the impact resistance, bending strength and toughness of the PP recycled material. At the same time, the whiteness of calcium carbonate ≥ 90% is used to replace white pigment to achieve whitening effect.

5. The lightweight PP modified material for automobile bumper according to claim 1, characterized in that: The toughening agent accounts for 14.7% of the weight of the modified material raw material. The toughening agent is POE 8200 polyolefin elastomer, and the toughening agent also includes adding mineral fiber for further reinforcement. In step (3), the mineral fiber is added to the twin-screw extruder by the weight loss method. The mineral fiber is one or more of glass fiber, silicon oxide whisker or aluminum borate whisker.

6. The lightweight PP modified material for automobile bumper according to claim 1, characterized in that: The antioxidant is a mixture of one or more of antioxidant DLTP, antioxidant 168 or antioxidant 1010, which is used to prevent high-temperature oxidation during the processing of the modified material, delay the aging speed of the bumper product, and extend the service life of the bumper product.

7. The lightweight PP modified material for automobile bumper according to claim 1, characterized in that: The crosslinking agent uses bismaleimide BMI, a bifunctional compound with maleimide MI as an active end group, to provide good mechanical properties and stability.

8. The lightweight PP modified material for automobile bumper according to claim 1, characterized in that: The lubricant is one or more of polyethylene wax, calcium stearate, zinc stearate, and stearic acid amide, and is used to improve the fluidity of the product during extrusion molding.

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