Polypropylene material for automobile bumpers and preparation method thereof

Abstract

The invention provides a polypropylene material for automobile bumpers, which comprises the following components in percentage by weight: 50-99% of polypropylene resin, 45% of flexibilizer, 4% of compatibilizer, 0.5% of antioxidant, 0.2% of light stabilizer and 0.3% of anti-aging agent. By selecting the polypropylene resin as a basic system, the EPSDM and the carbon fiber (CF) as toughening agents and the PP grafted maleic anhydride (PP-g-MAH) as a compatibilizer, the comprehensive performance requirements of high modulus and high toughness are met, other auxiliaries are combined on the basis, the aging resistance is met, and the obtained material has excellent performance and can be used as a special automobile bumper material.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and mainly to a polypropylene material for automobile bumpers and a preparation method thereof. Background Art

[0002] The car bumper plays a vital role in the crash resistance and energy absorption of the car during a collision, and can reduce the various injuries caused to people during a car collision. Therefore, the materials used for the car bumper are required to have good crash resistance and impact performance, and the materials are required to have good aging resistance and weather resistance. The car bumper is a large car exterior component, usually made by injection molding. Since the bumper has a relatively large surface area, a complex shape, and a thin wall, it is necessary to ensure that the rigidity and toughness of the material are balanced at the same time. Therefore, in order to ensure the smooth progress of the molding process, good fluidity is a necessary condition for the production of car bumper materials.

[0003] Car bumpers are usually made of polymer materials, among which polypropylene (PP) has the advantages of low cost, easy processing, recyclability, and low density. In addition, due to its elastomeric properties and ability to meet strict weight and performance standards, it can effectively disperse impact energy. Therefore, PP has become a popular choice for manufacturing car bumper materials.

[0004] With the development of technology and the further improvement of the requirements for lightweight automobiles, steel used in automobile bumpers has been replaced by plastics, and the thickness of automobile bumpers has also been further reduced, so there are higher requirements for PP bumper materials.

[0005] Therefore, it is necessary to design a special polypropylene material for automobile bumpers with high impact, high modulus, high toughness and long-term use. Summary of the invention

[0006] The purpose of the present invention is to prepare a polypropylene material for automobile bumper in view of the shortcomings of the prior art. By selecting polypropylene resin as the basic system and adding other additives on this basis, the purpose is to make the prepared special polypropylene material for automobile bumper meet the comprehensive performance requirements of high impact, high modulus, high toughness, aging resistance and weather resistance.

[0007] The technical solution adopted by the present invention is as follows:

[0008] A polypropylene material for automobile bumper, the components are proportioned according to percentage content, including:

[0009]

[0010] Preferably, the polypropylene resin has a melt flow rate MI ≥ 15g / 10min and a density of 0.90g / cm 3, Rockwell hardness 98, softening point 125 ℃ recycled polypropylene resin.

[0011] Preferably, the toughening agent is EPDM elastomer and carbon fiber (CF), wherein the density of EPDM elastomer is 0.86 g / cm 3 , the melt index range is 3.4g / 10min; the density of carbon fiber (CF) is 1.75g / cm 3 , with a diameter of 7μm.

[0012] Preferably, the compatibilizer is PP grafted maleic anhydride (PP-g-MAH), the grafting rate is 0.1%, and the melt index is 80-100 g / 10 min.

[0013] Preferably, the antioxidant is a mixture of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and tris(2·4-di-tert-butylphenyl) phosphite.

[0014] Preferably, the light stabilizer is selected from one or a combination of two of hindered amine, benzotriazole and salicylate light stabilizers.

[0015] Preferably, the anti-aging agent contains a 2,2,6,6-tetramethyl-4-piperidinyl stearate compound.

[0016] A method for preparing the above-mentioned polypropylene material for automobile bumper comprises the following steps:

[0017] According to the above weight percentage ratio, polypropylene resin, toughening agent, compatibilizer, antioxidant, light stabilizer and anti-aging agent are weighed, and the weighed raw materials are fully mixed through a twin-screw extruder, using a TE-20 co-rotating twin-screw extruder with an aspect ratio of 32, a screw diameter of 21.7 mm, and a main motor power of 7.5 kW. The temperature control range of each section is 175°C to 180°C (180°C-185°C-185°C-180°C-180°C), the main engine frequency is 9.0 Hz, and the feed frequency is 8.0 Hz; a crusher is used for crushing and granulation, and then a vacuum dryer is used for drying at about 80°C for about 8 hours; finally, a twin-screw injection molding machine is used for molding, and a room temperature treatment is performed for 36 hours to eliminate internal stress to obtain a polypropylene composite material.

[0018] Beneficial effects of the present invention:

[0019] The present invention prepares a carbon fiber reinforced polypropylene / ethylene-propylene-diene copolymer composite material (CF / PP / EPDM) by using mechanical melt mixing, wherein PP is the matrix, EPDM and CF are reinforcing phases, and polypropylene grafted maleic anhydride (PP-g-MAH) is the compatibility. The main focus of this invention is to study the effect of CF / EPDM on the impact resistance of PP-based composite materials, and to determine the potential mechanism of synergistic toughening through chemical structure analysis. The combined toughening of EPDM and CF greatly improves the impact strength, toughness, aging resistance and weather resistance of the composite material, and also successfully improves the heat resistance of the composite material. The material prepared by the present invention also has high fluidity and can meet the requirements of various vehicle models for bumper materials. DETAILED DESCRIPTION

[0020] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0021] Example 1

[0022] The components are calculated by percentage, and 10kg of polypropylene resin, 9kg of EPDM, 0.8kg of PP-g-MAH, 0.1kg of antioxidant, 0.04kg of light stabilizer, and 0.06kg of anti-aging agent are weighed. The weighed raw materials are fully mixed through a twin-screw extruder, using a TE-20 co-rotating twin-screw extruder with an aspect ratio of 32, a screw diameter of 21.7mm, and a main motor power of 7.5kW. The temperature control range of each section is 175℃~180℃ (180℃-185℃-185℃-180℃-180℃), the main frequency is 9.0Hz, and the feed frequency is 8.0Hz; a crusher is used for crushing and granulation, and then a vacuum dryer is used for drying at about 80℃ for about 8 hours; finally, a twin-screw injection molding machine is used for molding, and a room temperature treatment is performed for 36 hours to eliminate internal stress to obtain a polypropylene composite material.

[0023] Example 2

[0024] The components are calculated by percentage, and 10kg of polypropylene resin, 8kg of EPDM, 0.6kg of CF, 0.8kg of PP-g-MAH, 0.1kg of antioxidant, 0.04kg of light stabilizer, and 0.06kg of anti-aging agent are weighed. The weighed raw materials are fully mixed through a twin-screw extruder, which uses a TE-20 co-rotating twin-screw extruder with an aspect ratio of 32, a screw diameter of 21.7mm, and a main motor power of 7.5kW. The temperature control range of each section is 175℃~180℃ (180℃-185℃-185℃-180℃-180℃), the main frequency is 9.0Hz, and the feed frequency is 8.0Hz; a crusher is used for crushing and granulation, and then a vacuum dryer is used for drying at about 80℃ for about 8 hours; finally, a twin-screw injection molding machine is used for molding, and a room temperature treatment is performed for 36 hours to eliminate internal stress to obtain a polypropylene composite material.

[0025] Example 3

[0026] The components are calculated by percentage, and 10kg of polypropylene resin, 8kg of EPDM, 1kg of CF, 0.8kg of PP-g-MAH, 0.1kg of antioxidant, 0.04kg of light stabilizer, and 0.06kg of anti-aging agent are weighed. The weighed raw materials are fully mixed through a twin-screw extruder, which uses a TE-20 co-rotating twin-screw extruder with an aspect ratio of 32, a screw diameter of 21.7mm, and a main motor power of 7.5kW. The temperature control range of each section is 175℃~180℃ (180℃-185℃-185℃-180℃-180℃), the main frequency is 9.0Hz, and the feed frequency is 8.0Hz; a crusher is used for crushing and granulation, and then a vacuum dryer is used for drying at about 80℃ for about 8 hours; finally, a twin-screw injection molding machine is used for molding, and a room temperature treatment is performed for 36 hours to eliminate internal stress to obtain a polypropylene composite material.

[0027] Example 4

[0028] The components are calculated by percentage, and 10kg of polypropylene resin, 7.6kg of EPDM, 1.4kg of CF, 0.8kg of PP-g-MAH, 0.1kg of antioxidant, 0.04kg of light stabilizer, and 0.06kg of anti-aging agent are weighed. The weighed raw materials are fully mixed through a twin-screw extruder, which uses a TE-20 co-rotating twin-screw extruder with an aspect ratio of 32, a screw diameter of 21.7mm, and a main motor power of 7.5kW. The temperature control range of each section is 175℃~180℃ (180℃-185℃-185℃-180℃-180℃), the main frequency is 9.0Hz, and the feeding frequency is 8.0Hz; a crusher is used for crushing and granulation, and then a vacuum dryer is used for drying at about 80℃ for about 8 hours; finally, a twin-screw injection molding machine is used for molding, and a room temperature treatment is performed for 36 hours to eliminate internal stress to obtain a polypropylene composite material.

[0029] Example 5

[0030] The components are calculated by percentage, and 10kg of polypropylene resin, 7.2kg of EPDM, 1.8kg of CF, 0.8kg of PP-g-MAH, 0.1kg of antioxidant, 0.04kg of light stabilizer, and 0.06kg of anti-aging agent are weighed. The weighed raw materials are fully mixed through a twin-screw extruder, which uses a TE-20 co-rotating twin-screw extruder with an aspect ratio of 32, a screw diameter of 21.7mm, and a main motor power of 7.5kW. The temperature control range of each section is 175℃~180℃ (180℃-185℃-185℃-180℃-180℃), the main frequency is 9.0Hz, and the feed frequency is 8.0Hz; a crusher is used for crushing and granulation, and then a vacuum dryer is used for drying at about 80℃ for about 8 hours; finally, a twin-screw injection molding machine is used for molding, and a room temperature treatment is carried out for 36 hours to eliminate internal stress to obtain a polypropylene composite material.

[0031] Comparative Example 1

[0032] The components are calculated by percentage, and 19.8kg of polypropylene resin, 0.1kg of antioxidant, 0.04kg of light stabilizer, and 0.06kg of anti-aging agent are weighed. The weighed raw materials are fully mixed through a twin-screw extruder, using a TE-20 co-rotating twin-screw extruder with an aspect ratio of 32, a screw diameter of 21.7mm, and a main motor power of 7.5kW. The temperature control range of each section is 175℃~180℃ (180℃-185℃-185℃-180℃-180℃), the main frequency is 9.0Hz, and the feed frequency is 8.0Hz; a crusher is used for crushing and granulation, and then a vacuum dryer is used to dry at about 80℃ for about 8 hours; finally, a twin-screw injection molding machine is used for molding, and a room temperature treatment is performed for 36 hours to eliminate internal stress to obtain a polypropylene composite material.

[0033] The polypropylene composite component formula table of each embodiment and comparative example is shown in Table 1.

[0034] Table 1 Component formula of polypropylene composite materials of various embodiments and comparative examples

[0035] Components Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 PP 50％ 50％ 50％ 50％ 50％ 99％ EPDM 45％ 42％ 40％ 38％ 36％ 0 CF 0 3％ 5％ 7％ 9％ 0 PP-g-MAH 4％ 4％ 4％ 4％ 4％ 0 Antioxidants 0.5％ 0.5％ 0.5％ 0.5％ 0.5％ 0.5％ Light Stabilizer 0.2％ 0.2％ 0.2％ 0.2％ 0.2％ 0.2％ Anti-aging agents 0.3％ 0.3％ 0.3％ 0.3％ 0.3％ 0.3％

[0036] The polypropylene materials of the embodiments and comparative examples were injection molded into standard specimens and tested according to the standards. The test performance is shown in Table 2.

[0037] Table 2 Test performance results of polypropylene composite materials of various embodiments and comparative examples

[0038]

[0039]

[0040] It can be seen from the above tests that the elongation at break of the polypropylene material prepared by the present invention is 941.2%, the weather resistance is ≥800 hours (xenon lamp aging), and the impact strength reaches 34.5MPa. Compared with ordinary polypropylene materials without adding EPDM and CF toughening agents, the composite toughening of EPDM and CF effectively improves the impact strength of the composite material, with the maximum increase exceeding 1000%, and the addition of 9wt% CF successfully improves the heat resistance of the composite material. The material of the present invention has excellent mechanical strength, good thermal stability and aging resistance, and can be used as a good material for automobile bumpers.

[0041] The technical solutions provided by the embodiments of the present invention are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the methods and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A polypropylene material for automobile bumper, characterized in that: The raw materials in parts by weight include:

2. The polypropylene material for automobile bumper according to claim 1, characterized in that: The polypropylene resin has a melt flow rate MI ≥ 15g / 10min and a density of 0.90g / cm 3 , Rockwell hardness 98, softening point 125 ℃ recycled polypropylene resin.

3. The polypropylene material for automobile bumper according to claim 1, characterized in that: The toughening agent is EPDM elastomer and carbon fiber (CF), wherein the density of EPDM elastomer is 0.86g / cm 3 , the melt index range is 3.4g / 10min; the density of carbon fiber (CF) is 1.75g / cm 3 , with a diameter of 7μm.

4. The polypropylene material for automobile bumper according to claim 1, characterized in that: The compatibilizer is PP grafted maleic anhydride (PP-g-MAH), the grafting rate is 0.1%, and the melting index is 80-100 g / 10 min.

5. The polypropylene material for automobile bumper according to claim 1, characterized in that: The antioxidant is a mixture of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate and tris(2·4-di-tert-butylphenyl) phosphite.

6. The polypropylene composite material for automobile bumper according to claim 1, characterized in that: The light stabilizer is selected from hindered amine, benzotriazole and salicylate light stabilizers, or a combination of two thereof.

7. The polypropylene composite material for automobile bumper according to claim 1, characterized in that , the antioxidant contains a 2,2,6,6-tetramethyl-4-piperidinyl stearate compound.

8. A method for preparing a polypropylene material for automobile bumper according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Weigh polypropylene resin, toughening agent, compatibilizer, antioxidant, light stabilizer and anti-aging agent according to the weight proportion described in any one of claims 1 to 7, and fully mix the weighed raw materials through a twin-screw extruder, with the temperature control range of each section being 175°C to 180°C (180°C-185°C-185°C-180°C-180°C), the main engine frequency being 9.0Hz, and the feed frequency being 8.0Hz; S2, after completing step S1, crushing and granulating with a crusher, and then drying with a vacuum dryer at about 80° C. for about 8 hours; S3. After completing step S2, use a twin-screw injection molding machine to form the product, and perform room temperature treatment for 36 hours to eliminate internal stress.

9. The method for preparing a polypropylene material for an automobile bumper according to claim 8, characterized in that: The twin-screw extruder is a TE-20 co-rotating twin-screw extruder with a length-to-diameter ratio of 32, a screw diameter of 21.7 mm, and a main motor power of 7.5 kW.

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