PP plastic for automobile bumper and preparation method of PP plastic

Abstract

The invention provides PP (polypropylene) plastic for an automobile bumper and a preparation method of the PP plastic, and the PP plastic comprises the following components in parts by weight: 75-90 parts of polypropylene, 10-15 parts of a cyclized olefin copolymer, 0.1-2 parts of a modified beta nucleating agent, 10-30 parts of a light stabilizer and 0.5-5 parts of an antioxidant. The polypropylene comprises block co-polypropylene; the modified beta nucleating agent is obtained by physically blending an amide nucleating agent and erucyl amide; the cyclized olefin copolymer comprises polypropylene containing an aliphatic ring or an aromatic ring. Under the combined action of the block co-polypropylene, the cyclized olefin copolymer and the modified beta nucleating agent, the PP plastic has high tensile strength and high toughness at the same time.

Description

Technical Field

[0001] The invention relates to the field of polypropylene materials, and in particular to PP plastic for automobile bumpers and a preparation method thereof. Background Art

[0002] The material of automobile bumpers is mainly polypropylene (PP). Compared with metal bumpers many years ago, plastic bumpers have the following advantages: (1) Plastic bumpers can act as a buffer in low-speed collisions, effectively reducing injuries to pedestrians; (2) Plastic bumpers can effectively reduce vehicle weight, making cars lighter and safer; (3) Plastic bumpers are easier to repair. Minor scratches only require repainting, without the need for sheet metal repair; (4) Plastic bumpers can easily create a more beautiful and aerodynamic front face shape, further reducing vehicle energy consumption and complying with the general trend of energy conservation and emission reduction. However, with the development of the automotive industry and the increasing demand of consumers for the quality of automotive interiors, polypropylene materials face many challenges in practical applications. The disadvantage of PP's poor impact resistance limits its scope of application.

[0003] At present, there are many studies on the mechanical properties and crystallization behavior of β-type PP. In addition to maintaining some of the good comprehensive properties of α-type PP, β-type PP also has better toughness. Its elongation at break and notched impact strength are higher than those of α-type PP. This is because β-spherulites grow in a spiral shape around a center. PP has a simple layered morphology and is easy to stretch. β-spherulites are stable before they are stretched to the yield point, and then they will transform into α-crystals in the neck region. Therefore, β-type PP has a good toughening effect. Adding β-nucleating agents is currently the most convenient way to obtain high-quality PP in industry. There are many types of β-nucleating agents, which can be roughly divided into: (1) organic, mainly including polycyclic aromatic hydrocarbons, organic carboxylic acids and their salts, and aromatic amides; (2) rare earth; (3) inorganic. However, aromatic amides still have the problem of uneven dispersion in PP, resulting in poor crystallization effect.

[0004] Therefore, it is necessary to develop a material that can meet both high strength and good toughness to meet the stringent requirements of the modern automotive industry for parts. Summary of the Invention

[0005] Aiming at overcoming the deficiencies of the prior art, the present invention provides a method for modifying a β-crystal nucleating agent and a PP plastic with high strength and good toughness. The invention also provides a preparation method thereof.

[0006] In one aspect, the present invention provides a PP plastic for automobile bumpers, the PP plastic comprising the following components in parts by weight: 75 to 90 parts of polypropylene, 10 to 15 parts of a cyclized olefin copolymer, 0.1 to 2 parts of a modified β-nucleating agent, 10 to 30 parts of a light stabilizer, and 0.5 to 5 parts of an antioxidant; The polypropylene includes block copolymer polypropylene; The modified β nucleating agent is obtained by physically blending an amide nucleating agent with erucamide; The cyclized olefin copolymer includes polypropylene containing an aliphatic ring or an aromatic ring.

[0007] Furthermore, the light stabilizer is an ultraviolet light stabilizer, and the ultraviolet light stabilizer includes at least one of phenyl o-hydroxybenzoate, 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone, 2-(2-hydroxy-3,5-di-tert-phenyl)-5-chlorobenzotriazole and monobenzoic acid resorcinol ester.

[0008] Furthermore, the antioxidant includes at least one of a phenolic antioxidant, an amine antioxidant, and a phosphite composite antioxidant; Furthermore, the amide nucleating agent includes NJ STAR NU-100.

[0009] Furthermore, the mass ratio of the amide compound to erucamide is 1:(1.8~2).

[0010] Furthermore, the melt flow rate of the polypropylene is 5-50 g / 10 min.

[0011] Furthermore, the melt flow rate of the polypropylene is 5-30 g / 10 min.

[0012] In a second aspect, the present application provides a method for preparing the above-mentioned PP plastic for automobile bumpers, comprising the following steps: Step 1: Put polypropylene, cyclized olefin copolymer, and antioxidant into a high-speed mixer and mix them in parts by weight to obtain a premix; Step 2: Place the premix on the main loss-in-weight scale and add it to the twin-screw extruder through the main feed port. Place the modified β-nucleating agent on the secondary loss-in-weight scale and add it to the twin-screw extruder through the side feed port for melt extrusion. Step 3: The extruded molten material is subjected to strip drawing, cooling, and pelletizing to obtain the PP plastic for automobile bumper.

[0013] Furthermore, in step 1, the mixing time is 30 to 60 minutes.

[0014] Furthermore, in step 2, the temperature of each zone of the screw is 150° C. to 220° C., and the screw speed is 250 to 600 rpm.

[0015] The PP plastic for automobile bumpers provided in this application has the following functions: 1) The present invention uses erucamide to modify amide compounds to form a modified β-nucleating agent with a hydrogen bond self-assembly structure, which can effectively promote the dispersion of amide compounds in polypropylene; at the same time, it improves the crystallization properties of PP plastics and increases the toughness of PP plastics; erucamide also plays a lubricating role and improves the flexural strength.

[0016] 2) This application adds a cyclized olefin copolymer to PP plastic. Since the rigid cyclic structure can provide polar sites, it forms an interpenetrating network with the non-polar segments of polypropylene through physical entanglement or chemical grafting, which significantly improves the strength of the PP plastic. Under the combined action of block copolymer polypropylene and modified β-nucleating agent, the PP plastic has high tensile strength and high toughness. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the synthesis mechanism of modified β-nucleating agent. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] In order to illustrate the technical solution of the present invention, specific embodiments are provided below.

[0020] In a first aspect, the present invention provides a PP plastic for automobile bumpers, comprising the following components in parts by weight: 75 to 90 parts of polypropylene, such as 75, 78, 80, 83, 85, 88, 90, etc., but not limited to the values listed, and combinations not listed within the range are also applicable; 10 to 15 parts of a cyclized olefin copolymer, such as 10, 11, 12, 13, 14, 15, etc., but not limited to the values listed, and combinations not listed within the range are also applicable; 0.1 to 2 parts of a modified β-nucleating agent, such as 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 10.10, 15.0, 10.20, 10.30, 10.40, 10.50, 10.60, 10.70, 10.80, 10.90, 10. 7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, etc., but not limited to the listed values, and combinations not listed in this range are also applicable; 10-30 parts of light stabilizer, such as 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, etc., but not limited to the listed values, and combinations not listed in this range are also applicable; 0.5-5 parts of antioxidant, such as 0.5, 1, 2, 3, 4, 5, etc., but not limited to the listed values, and combinations not listed in this range are also applicable; The polypropylene includes block copolymer polypropylene; The modified β nucleating agent is obtained by physically blending an amide nucleating agent with erucamide; The modified β nucleating agent prepared in this embodiment is as shown in the attached specification. Figure 1 As shown in the figure, the unmodified amide nucleating agent and erucamide present irregular atomic distribution. After the two are physically blended, the carbonyl group in the amide nucleating agent forms hydrogen bonds with the amino group in erucamide, and a regularly arranged complex is formed through hydrogen bond self-assembly, which effectively improves the dispersibility of the amide nucleating agent in PP and induces the increase of β crystals. Since erucamide has a long carbon chain, it reduces the melt viscosity and increases the diffusion of the amide nucleating agent in PP. At the same time, after the modified β nucleating agent is added, the long-chain alkane of erucamide is interspersed in the gaps of the straight-chain alkane molecular chain of PP, forming a "molecular ball bearing" effect, which can reduce chain entanglement, reduce the van der Waals force / friction resistance between molecular chains, promote chain segment slippage, and increase bending performance.

[0021] The cyclized olefin copolymer includes polypropylene containing an aliphatic ring or an aromatic ring.

[0022] In this embodiment, block copolymer polypropylene is used to form a microphase separation structure by introducing flexible chain segments such as ethylene, forming energy dissipation units in the polypropylene matrix. Therefore, block copolymer polypropylene is more suitable for preparing PP plastic for automobile bumpers than homopolymer polypropylene. The modified β-nucleating agent formed by modifying amide compounds with erucamide to form a hydrogen bond self-assembly structure can effectively promote the dispersion of amide compounds in polypropylene; at the same time, it improves the crystallization properties of PP plastics and increases the toughness of PP plastics; erucamide also plays a lubricating role and improves the bending strength; Cycled olefin copolymers can provide polar sites due to their rigid cyclic structure, forming an interpenetrating network with the non-polar segments of polypropylene through physical entanglement or chemical grafting. The rigid structure of cyclized olefin copolymers can serve as heterogeneous nucleation points, promoting the formation of polypropylene β crystals, significantly improving the strength of PP plastics. This embodiment obtains a material having strong tensile properties and excellent toughness by rationally combining components of polypropylene, cyclized olefin copolymer, modified β-nucleating agent, light stabilizer, and antioxidant.

[0023] In some embodiments, the light stabilizer is an ultraviolet light stabilizer, and the ultraviolet light stabilizer includes at least one of phenyl o-hydroxybenzoate, 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone, 2-(2-hydroxy-3,5-di-tert-phenyl)-5-chlorobenzotriazole and monobenzoic acid resorcinol ester.

[0024] In a preferred embodiment, the stabilizer is resorcinol monobenzoate.

[0025] In some embodiments, the antioxidant includes at least one of a phenolic antioxidant, an amine antioxidant, and a phosphite composite antioxidant; In a preferred embodiment, the antioxidant is selected from BASF 1010.

[0026] In some embodiments, the amide nucleating agent includes NJ STAR NU-100.

[0027] In some embodiments, the mass ratio of the amide compound to erucamide is 1:(1.8~2), such as 1:1.8, 1:1.85, 1:1.9, 1:1.95, 1:2, etc., but is not limited to the listed values, and combinations not listed in this range are also applicable.

[0028] In some embodiments, the melt flow rate of the polypropylene is 5-50 g / 10 min, such as 5, 10, 20, 30, 40, 50, etc., but is not limited to the listed values, and combinations not listed in this range are also applicable.

[0029] In some embodiments, the polypropylene has a melt flow rate of 5-30 g / 10 min.

[0030] In a second aspect, the present application provides a method for preparing the above-mentioned PP plastic for automobile bumpers, comprising the following steps: Step 1: Put polypropylene, cyclized olefin copolymer, and antioxidant into a high-speed mixer and mix them in parts by weight to obtain a premix; Step 2: Place the premix on the main loss-in-weight scale and add it to the twin-screw extruder through the main feed port. Place the modified β-nucleating agent on the secondary loss-in-weight scale and add it to the twin-screw extruder through the side feed port for melt extrusion. Step 3: The extruded molten material is subjected to strip drawing, cooling, and pelletizing to obtain the PP plastic for automobile bumper.

[0031] Furthermore, in step 1, the mixing time is 30 to 60 minutes, such as 30, 35, 40, 45, 50, 55, 60, etc., but is not limited to the listed values, and combinations not listed within the range are also applicable.

[0032] Furthermore, in step 2, the temperature of each zone of the screw is 150°C to 220°C, such as 150, 160, 170, 180, 190, 200, 210, 220, etc., but is not limited to the listed values, and combinations not listed in this range are also applicable; the screw speed is 250 to 600 rpm, such as 250, 300, 400, 500, 600, etc., but is not limited to the listed values, and combinations not listed in this range are also applicable.

[0033] The present invention is further described below through preparation examples and examples.

[0034] Preparation Example In a high-speed stirrer, 10 g of an amide compound (brand NJ STAR NU-100, purchased from Shin Nippon Chemical Co., Ltd.) and 20 g of erucamide (purchased from Qingdao Sino New Materials Co., Ltd.) were added and stirred for 2-5 minutes to obtain a modified β-nucleating agent. Example 1

[0035] The present invention provides a method for preparing PP plastic for automobile bumpers: Step 1: By weight, 80 g of polypropylene (ExxonMobil™ PP7143KNE1, purchased from ExxonMobil), 12 g of cyclized olefin copolymer (TOPAS 8007, purchased from Polyplastics Co., Ltd.), 20 g of light stabilizer (resorcinol monobenzoate, purchased from Shanghai Baishun Biotechnology Co., Ltd.), and 1 g of antioxidant (1010, purchased from BASF) were placed in a high-speed mixer and mixed for 30 minutes to obtain a premix; Step 2: Place the premix on the main loss-in-weight scale and add it to the twin-screw extruder through the main feed port. Place 1g of the modified β-nucleating agent on the secondary loss-in-weight scale and add it to the twin-screw extruder through the side feed port. The temperature of each screw zone is 150°C, the screw speed is 500 rpm, and melt extrusion is performed. Step 3: The extruded molten material is subjected to strip drawing, cooling, and pelletizing to obtain the PP plastic for automobile bumper. Example 2

[0036] Most of the steps in this embodiment are the same as those in Example 1, except that 75 g of polypropylene is added in step 1. Example 3

[0037] Most of the steps in this embodiment are the same as those in Example 1, except that 85 g of polypropylene is added in step 1. Example 4

[0038] Most of the steps in this embodiment are the same as those in Example 1, except that 90 g of polypropylene is added in step 1. Example 5

[0039] Most of the steps in this example are the same as those in Example 1, except that 10 g of cyclized olefin copolymer is added in step 1. Example 6

[0040] Most of the steps in this example are the same as those in Example 1, except that 15 g of cyclized olefin copolymer is added in step 2. Example 7

[0041] Most of the steps in this embodiment are the same as those in Example 1, except that 0.1 g of a modified β-nucleating agent is added in step 2. Example 8

[0042] Most of the steps in this embodiment are the same as those in Example 1, except that 2 g of modified β-nucleating agent is added in step 2.

[0043] Comparative Example 1 Most of the steps of this comparative example are the same as those of Example 1, except that no cyclized olefin copolymer is added in step 1 and no modified β-nucleating agent is added in step 2.

[0044] Comparative Example 2 Most of the steps in this comparative example are the same as those in Example 1, except that no cyclized olefin copolymer is added in step 1.

[0045] Comparative Example 3 Most of the steps of this comparative example are the same as those of Example 1, except that no modified β-nucleating agent is added in step 2.

[0046] Comparative Example 4 Most of the steps of this comparative example are the same as those of Example 1, except that 1 g of the modified β-nucleating agent in step 2 of Example 1 is replaced by 1 g of an amide compound.

[0047] Comparative Example 5 Most of the steps of this comparative example are the same as those of Example 1, except that 1 g of the modified β-nucleating agent in step 2 of Example 1 is replaced by 1 g of erucamide.

[0048] Comparative Example 6 Most of the steps of this comparative example are the same as those of Example 1, except that 20 g of cyclized olefin copolymer is added in step 1.

[0049] Comparative Example 7 Most of the steps of this comparative example are the same as those of Example 1, except that 3 g of modified β-nucleating agent is added in step 2.

[0050] Injection molding process conditions: Set the temperatures of barrel zones 1, 2, and 3 to 180°C, 200°C, and 220°C, respectively, with an injection pressure of 20 MPa. The hold time is 10 seconds, the cooling time is 60 seconds, and the mold temperature is 40-50°C. The automobile bumpers prepared in the above-mentioned embodiments and comparative examples were injection molded with PP plastic and then subjected to the following tests.

[0051] Tensile test: According to GB / T 1040.2-2022 standard, tensile speed 50mm / min, test temperature 20-30℃; Bending test: Tested according to GB / T 9341-2008 standard, test speed 2mm / min, test temperature 20-30℃; Simply supported beam notched impact test: Tested according to GB / T 1043.1-2008 standard, test temperature 20-30℃.

[0052] The above test results are shown in Table 1.

[0053] Table 1 Group Tensile strength (MPa) Flexural strength (MPa) <![CDATA[Izod impact strength (kJ / m 2 )]]> Example 1 30.90 37.78 40.67 Example 2 27.56 35.12 38.21 Example 3 28.65 36.28 39.12 Example 4 28.02 36.15 39.01 Example 5 26.54 38.43 35.36 Example 6 27.51 35.26 36.39 Example 7 26.51 33.21 33.55 Example 8 27.44 36.52 34.65 Comparative Example 1 23.45 28.14 31.28 Comparative Example 2 24.21 29.56 32.78 Comparative Example 3 26.53 27.11 29.12 Comparative Example 4 26.53 30.90 31.87 Comparative Example 5 25.20 34.26 32.75 Comparative Example 6 28.00 30.21 32.11 Comparative Example 7 24.99 33.01 33.98 Combining Comparative Example 1 with Comparative Example 1, it can be seen that the tensile strength of the PP plastic for automobile bumpers prepared by the present invention is 1.3 times that of pure polypropylene, the flexural strength is 1.34 times that of pure polypropylene, and the notched impact strength is 1.3 times that of pure polypropylene; Combining Comparative Example 1 with Comparative Examples 1-3, it can be seen that when no cyclized olefin copolymer is added in Comparative Example 2 and no modified β-nucleating agent is added in Comparative Example 3, the overall comprehensive mechanical properties are worse than those in Example 1; in Comparative Example 3, when only the cyclized olefin copolymer is added without the β-nucleating agent, the strength of the PP plastic is significantly increased relative to Comparative Example 1, from 23.45 MPa to 26.53 MPa. At the same time, the addition of the rigid structure also reduces the bending performance and toughness of the PP plastic; when only the modified β-nucleating agent is added in Comparative Example 2, the increase in flexural strength and notched impact strength is smaller than that in Comparative Example 1 due to the inability to exert a synergistic effect with the cyclized olefin copolymer.

[0054] Compared to Comparative Example 1, Comparative Example 4 showed a 13.1% increase in tensile strength and a 9.8% increase in flexural strength, indicating some improvement in strength. However, its notched impact strength increased only slightly by 1.9%. Referring to the modified system of Example 1, it can be seen that the unmodified amide nucleating agent still has some effect on improving the system's tensile and flexural properties, but has little effect on impact resistance. Compared to Comparative Example 1, Comparative Example 5 showed a 21.7% increase in flexural strength, indicating that the addition of erucamide alone can effectively improve the material's flexural properties. However, its tensile strength increased by 7.5% and its notched impact strength increased by 4.7%. Referring to the modified system of Example 1, it can be seen that the improvement in tensile and impact resistance is limited.

[0055] Comparing Examples 1-4, it can be seen that the addition amount of polypropylene is in the range of 75-90 parts, with 80 parts being the optimal value for comprehensive performance: tensile strength of 30.90 MPa, flexural strength of 37.78 MPa, and notched impact strength of 40.67 kJ / m². When the addition amount is reduced, the matrix is insufficient, the interaction between the molecular chains is weakened, and the lubricating effect of erucamide is weakened. When the addition amount is increased, the introduction of excessive amorphous regions reduces the crystallinity, resulting in reduced strength and toughness. At the same time, the increase in the amount of polypropylene affects the proportion of the modified β-nucleating agent in the matrix. The increase in the amount may lead to excessive dilution of erucamide, reducing lubrication efficiency and thus reducing bending performance.

[0056] By comparing Example 1 with Examples 5-6, it can be seen that the content of the cyclized olefin copolymer is reduced. For example, compared with Example 1, due to the small amount of cyclized structure added in Example 5, the rigid network will be incomplete and the stress transfer efficiency will be low, resulting in a significant decrease in strength; the rigid support will be weakened, and the molecular chain will easily slip, resulting in a slight increase in bending strength; and the nucleation points are sparse, the β-spherulites are large in size and unevenly distributed, resulting in weak stress buffering capacity.

[0057] Comparison of Example 1 and Comparative Example 6 shows that when 20 parts of the cyclized olefin copolymer is added, although the tensile strength is 28.00 MPa, which is not much different from Example 1, the flexural strength is reduced to 30.21 MPa. This is because the proportion of the cyclized structure in the copolymer molecules increases, which will lead to stress concentration points and rigid overload; the notched impact strength is reduced to 32.11 kJ / m 2 This is because excessive cyclized olefin copolymer will destroy the microphase separation structure of block copolymer PP, resulting in a decrease in toughness.

[0058] Comparing Example 1 and Examples 7-8, it can be seen that adding 0.1 parts of modified β-nucleating agent can significantly improve the conversion of PP plastic crystal form, and the synergistic effect is best when adding 1 part. Comparing Example 1 and Comparative Example 7, it can be seen that when 3 parts of modified β-nucleating agent are added, the tensile strength is as low as 24.99MPa. This may be due to the saturation of hydrogen bond self-assembly, the formation of large-sized aggregates between the amide nucleating agent and erucamide, which reduces the β-crystallization effect and produces internal defects, resulting in reduced tensile strength; the flexural strength is reduced to 33.01MPa, and the long chain of erucamide is excessively lubricated due to the increase in the amount of addition, which hinders the close arrangement of polypropylene molecular chains and weakens the rigidity; the notched impact strength is reduced to 33.98kJ / m 2 On the other hand, the rapid growth rate of β crystals may lead to uneven spherulite size, which ultimately leads to reduced toughness.

[0059] The above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they may still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. However, such modifications or replacements do not deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention and are intended to be included within the scope of protection of the present invention.

Claims

1. A PP plastic for automobile bumper, characterized in that: The PP plastic comprises the following components in parts by weight: 75 to 90 parts of polypropylene, 10 to 15 parts of cyclized olefin copolymer, 0.1 to 2 parts of modified β-nucleating agent, 10 to 30 parts of light stabilizer, and 0.5 to 5 parts of antioxidant; The polypropylene includes block copolymer polypropylene; The modified β nucleating agent is obtained by physically blending an amide nucleating agent with erucamide; The cyclized olefin copolymer includes polypropylene containing an aliphatic ring or an aromatic ring.

2. The PP plastic for automobile bumper according to claim 1, characterized in that: The light stabilizer is an ultraviolet light stabilizer, and the ultraviolet light stabilizer includes at least one of phenyl o-hydroxybenzoate, 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octyloxybenzophenone, 2-(2-hydroxy-3,5-di-tert-phenyl)-5-chlorobenzotriazole and monobenzoic acid resorcinol ester.

3. The PP plastic for automobile bumper according to claim 1, characterized in that: The antioxidant includes at least one of a phenolic antioxidant, an amine antioxidant, and a phosphite composite antioxidant.

4. The PP plastic for automobile bumper according to claim 1, characterized in that: The amide nucleating agent includes NJ STAR NU-100.

5. The PP plastic for automobile bumper according to claim 1, characterized in that: The mass ratio of the amide compound to erucamide is 1: (1.8~2).

6. The PP plastic for automobile bumper according to claim 1, characterized in that: The melt flow rate of the polypropylene is 5-50g / 10min.

7. The PP plastic for automobile bumper according to claim 6, characterized in that: The melt flow rate of the polypropylene is 5-30 g / 10 min.

8. The method for preparing the PP plastic for automobile bumper according to claim 1, comprising the following steps: Step 1: Put polypropylene, cyclized olefin copolymer, and antioxidant into a high-speed mixer and mix them in parts by weight to obtain a premix; Step 2: Place the premix on the main loss-in-weight scale and add it to the twin-screw extruder through the main feed port. Place the modified β-nucleating agent on the secondary loss-in-weight scale and add it to the twin-screw extruder through the side feed port for melt extrusion. Step 3: The extruded molten material is subjected to strip drawing, cooling, and pelletizing to obtain the PP plastic for automobile bumper.

9. The method for preparing PP plastic for automobile bumper according to claim 8, characterized in that: In step 1, the mixing time is 30 to 60 minutes.

10. The method for preparing PP plastic for automobile bumper according to claim 8, characterized in that: In step 2, the temperature of each zone of the screw is 150° C. to 220° C., and the screw speed is 250 to 600 rpm.

Images