A dynamically vulcanized low-temperature-resistant and high-impact polypropylene alloy and a preparation method thereof

Abstract

The present invention discloses a dynamically vulcanized low-temperature-resistant high-impact polypropylene alloy, comprising the following components in parts by weight: polypropylene: 70-90 parts by weight; ethylene-propylene rubber: 5-25 parts by weight; thermoplastic elastomer: 5-15 parts by weight; octylphenol-formaldehyde vulcanized resin: 0.1-3 parts by weight; stannous chloride: 0.008-0.36 parts by weight; zinc oxide: 0.1-0.75 parts by weight; stearic acid: 0.05-0.375 parts by weight; the thermoplastic elastomer is at least one of styrene-hydrogenated isoprene copolymer or styrene-hydrogenated isoprene-styrene copolymer. The present invention uses SEP or SEPS with relatively high low-temperature toughening efficiency to improve the low-temperature toughness of the material, and uses octylphenol-formaldehyde resin as a vulcanizing agent to dynamically vulcanize the ethylene-propylene rubber to improve the strength of the material, and achieves a notched impact strength of the material at -30°C of up to 50kJ / m 2 Under the condition of ensuring that the room temperature tensile strength of the material is not less than 30MPa, the rigidity and toughness balance of the material is achieved.

Description

Technical Field

[0001] The invention relates to a dynamically vulcanized low-temperature-resistant and high-impact-resistant polypropylene alloy and a preparation method thereof. Background Art

[0002] Polypropylene (PP) has the advantages of light weight, environmental protection, non-toxicity, and good comprehensive performance. It is widely used in home appliances, automobiles, daily necessities, chemicals and other fields. However, due to its molecular structure, PP is often brittle, especially in low temperature (or high speed) environment, it is very easy to suffer brittle failure, thus limiting its application in some extreme scenarios. Therefore, PP needs to be toughened and modified. Common toughening methods include: adding elastomer toughening agents, adding inorganic particle toughening agents, β-nucleating agent toughening, dynamic vulcanization toughening, etc. However, although common toughening methods have a significant effect on improving the room temperature toughness of PP, they have no obvious effect on the low temperature toughness of PP (below -20°C). On the other hand, dynamic vulcanization toughening often requires the introduction of elastomers at the same time, so its toughening effect is relatively good. However, when the dynamic vulcanizer is a peroxide vulcanizer, during the high temperature processing of PP, the peroxide can easily cause the degradation of PP, thereby limiting the toughening effect and may cause the strength of the material to decrease. When the dynamic vulcanizing agent is sulfur, the final product is dark in color and has a pungent odor, which limits the application of dynamically vulcanized toughened PP. Moreover, materials vulcanized with sulfur are prone to vulcanization reversion during secondary processing, resulting in a decrease in material performance. Therefore, for PP toughening, it is necessary to develop a non-toxic, odorless, suitable for secondary processing and effective toughening method for improving PP low-temperature toughness.

[0003] CN 113912948 A discloses a polypropylene nanocomposite material with low-temperature toughness and rigid-toughness balance and a preparation method thereof. In this method, the material can be toughened at low temperature by synergizing an elastomer with nano-silicon dioxide and combining it with dynamic vulcanization technology, and has good low-temperature toughness at ultra-low temperature (-30°C). However, the vulcanizing agent used in this method is a peroxide vulcanizing agent. If the production process is not well controlled, it is easy to cause the degradation of PP molecules during the processing, thereby causing a large fluctuation in the performance of the final product. On the other hand, this method requires the simultaneous introduction of nano-silicon dioxide particles, which is costly.

[0004] Polymer 112 (2017) 318-324 discloses a method of using EPDM and SEP to toughen PP. The problem with this method is that it requires the use of up to 44% of elastomer by weight to lower the brittle-to-ductile transition temperature (T bd ) drops to -30°C, and its notched impact strength at -30°C is about 20 kJ / m 2, the room temperature tensile strength is about 9MPa. Due to the large amount of elastomer used, not only does it increase the material cost, but it also causes the strength of the material at room temperature to be much lower than that of common PP and its modified products (about 20-30MPa). Summary of the invention

[0005] The object of the present invention is to provide a dynamically vulcanized low-temperature-resistant and high-impact polypropylene alloy and a production method thereof.

[0006] The technical solution adopted by the present invention is:

[0007] A dynamically vulcanized low-temperature-resistant and high-impact polypropylene alloy, the material comprising the following components in parts by weight:

[0008] Polypropylene: 70-90 parts by weight

[0009] EPDM: 5-25 parts by weight

[0010] Thermoplastic elastomer: 5-15 parts by weight

[0011] Octylphenol formaldehyde vulcanized resin: 0.1-3 parts by weight

[0012] Stannous chloride: 0.008-0.36 parts by weight

[0013] Zinc oxide: 0.1-0.75 parts by weight

[0014] Stearic acid: 0.05-0.375 parts by weight.

[0015] The thermoplastic elastomer is one or both of styrene-hydrogenated isoprene copolymer (SEP) and styrene-hydrogenated isoprene-styrene copolymer (SEPS).

[0016] The octylphenolformaldehyde vulcanized resin is a heat-reactive octylphenolformaldehyde vulcanized resin, and the alkylphenols in the molecular structure are connected by methylene ether bonds (-CH2OCH2-) and / or methylene bonds (-CH2-).

[0017] Commercially available octylphenol formaldehyde vulcanized resins such as SP-1045, HY-2045, etc. can be used.

[0018] The octylphenol formaldehyde vulcanized resin has two ends of the molecule capped with hydroxymethyl active groups, preferably with a mass content of 5 to 20%, more preferably 8 to 15%.

[0019] Furthermore, the low temperature resistant and high impact resistant polypropylene alloy may also contain a small amount of antioxidant, and the polypropylene alloy comprises the following components in parts by weight:

[0020] Polypropylene: 70-90 parts by weight

[0021] EPDM: 5-25 parts by weight

[0022] Thermoplastic elastomer: 5-15 parts by weight

[0023] Octylphenol formaldehyde vulcanized resin: 0.1-3 parts by weight

[0024] Stannous chloride: 0.008-0.36 parts by weight

[0025] Zinc oxide: 0.1-0.75 parts by weight

[0026] Stearic acid: 0.05-0.375 parts by weight

[0027] Antioxidant: 0.01 to 5 parts by weight.

[0028] The antioxidant is preferably one of antioxidant 1010 or antioxidant 1076 or a mixture of both.

[0029] Preferably, the low temperature resistant and high impact resistant polypropylene alloy is composed of the following components in parts by weight:

[0030] Polypropylene: 70-90 parts by weight

[0031] EPDM: 5-25 parts by weight

[0032] Thermoplastic elastomer: 5-15 parts by weight

[0033] Octylphenol formaldehyde vulcanized resin: 0.1-3 parts by weight

[0034] Stannous chloride: 0.008-0.36 parts by weight

[0035] Zinc oxide: 0.1-0.75 parts by weight

[0036] Stearic acid: 0.05-0.375 parts by weight

[0037] Antioxidant: 0.01 to 5 parts by weight.

[0038] Further, more preferably, the low temperature resistant and high impact resistant polypropylene alloy is composed of the following components in parts by weight:

[0039] Polypropylene: 75-85 parts by weight

[0040] EPDM: 15-25 parts by weight

[0041] Thermoplastic elastomer: 8-15 parts by weight

[0042] Octylphenol formaldehyde vulcanized resin: 0.5-2 parts by weight

[0043] Stannous chloride: 0.05-0.2 parts by weight

[0044] Zinc oxide: 0.3-0.7 parts by weight

[0045] Stearic acid: 0.15-0.35 parts by weight

[0046] Antioxidant: 0.05-2 parts by weight.

[0047] The amount of the octylphenol formaldehyde vulcanized resin is preferably 2-12% of the mass of the EPDM rubber, more preferably 4-10%.

[0048] The amount of stannous chloride used is preferably 8-12% of the mass of the octylphenol-formaldehyde resin, and more preferably 10%.

[0049] The amount of zinc oxide used is preferably 2-3% of the mass of the EPDM rubber, more preferably 2.5%.

[0050] The amount of stearic acid used is preferably 1-1.5% of the mass of the EPDM rubber, more preferably 1.25%.

[0051] The present invention also provides a method for preparing the low-temperature-resistant and high-impact-resistant polypropylene alloy, which is the following method (I) or method (II):

[0052] Method (I) Step-by-step method:

[0053] (1) According to the raw material ratio, polypropylene, ethylene propylene rubber, thermoplastic elastomer, part of stearic acid, part of zinc oxide, part of stannous chloride, and part of antioxidant are added, and melt blended by an internal mixer or melt extruded and granulated by a twin-screw extruder to obtain an intermediate material;

[0054] (2) The intermediate material, the remaining stearic acid, the remaining zinc oxide, the remaining stannous chloride, and the remaining antioxidant are melt-extruded and granulated by a twin-screw extruder, and an octylphenol formaldehyde vulcanized resin is added to the melting section of the twin-screw extruder for dynamic vulcanization, and extrusion granulation is performed to obtain a low-temperature resistant and high-impact resistant polypropylene alloy.

[0055] Furthermore, in the step (1), the amount of the added stearic acid, zinc oxide, stannous chloride and antioxidant is preferably 50-100% of the total amount of stearic acid, zinc oxide, stannous chloride and antioxidant, respectively, and the remaining stearic acid, zinc oxide, stannous chloride and antioxidant are added in step (2);

[0056] When the amounts of part of the stearic acid, part of the zinc oxide, part of the stannous chloride, and part of the antioxidant added in step (1) are 100% of the amounts of all the stearic acid, all the zinc oxide, all the stannous chloride, and all the antioxidant, respectively, it means that all the stearic acid, all the zinc oxide, all the stannous chloride, or all the antioxidant is added in step (1), and there is no need to add the corresponding raw materials in step (2).

[0057] When all the stearic acid, all the zinc oxide, all the stannous chloride and all the antioxidant are added in step (1), the octylphenol formaldehyde vulcanized resin in step (2) can be added together with the intermediate material.

[0058] The temperature of the internal mixer for melt blending in step (1) is preferably 140-230°C, and the temperature of the twin-screw extruder for melt extrusion granulation is preferably 140-230°C.

[0059] The typical extrusion process of the preferred twin-screw extruder is: conveying section temperature 90-180°C, melting section temperature 140-230°C, homogenizing section temperature 160-230°C, die temperature 160-230°C, and screw speed 50-150rpm.

[0060] Method (II) Single-step method:

[0061] For twin-screw extruders equipped with a separate metering feeding system and capable of segmented feeding, there is no need to use the step-by-step method. The steps of the single-step method are as follows:

[0062] Polypropylene, EPDM rubber and thermoplastic elastomer are fed into the main feeding port of the twin-screw extruder according to metering; stearic acid, zinc oxide and stannous chloride are fed into the main feeding port of the twin-screw extruder according to metering or from a secondary feeding port which is at least one barrel section away from the main feeding port; stearic acid, zinc oxide and stannous chloride can be fed from the same secondary feeding port, or respectively from 2 to 3 secondary feeding ports, and at least one barrel section is separated between two adjacent secondary feeding ports; octylphenol formaldehyde vulcanized resin is fed into the third feeding port arranged in the melting section or the homogenizing section according to metering; the third feeding port and the last secondary feeding port are separated by at least two barrel sections; when an antioxidant is used, the antioxidant can be fed from any feeding port; finally, a low-temperature resistant and high-impact polypropylene alloy is obtained through one-time extrusion.

[0063] Furthermore, the method comprises extrusion granulation at a temperature of 140 to 230°C.

[0064] Furthermore, the preferred typical extrusion process is: conveying section temperature 90-180°C, melting section temperature 140-230°C, homogenizing section temperature 160-230°C, die temperature 160-230°C, and screw speed 50-150rpm.

[0065] The low-temperature-resistant and high-impact polypropylene alloy provided by the present invention can be used to prepare materials such as automobile bumpers, washing machine liner, refrigerator lining, etc., and is suitable for use in application scenarios with excellent low-temperature (or high-speed) impact resistance.

[0066] The beneficial effects of the present invention are:

[0067] 1. Selecting SEP and / or SEPS, which can effectively improve the low-temperature toughness of the material, as auxiliary toughening modifiers for PP, combined with EPDM ternary rubber, can significantly improve the impact toughness of PP at low temperatures.

[0068] 2. Using phenolic resin as the vulcanizing agent for EPDM rubber can avoid the degradation of the PP matrix, and the final material is almost odorless, has good heat resistance, and does not undergo vulcanization reversion.

[0069] 3. No need to use nano-silica or add any inorganic fillers, which can effectively reduce material costs.

[0070] 4. Dynamic vulcanization of EPDM can effectively reduce the amount of elastomer used, ensuring that the PP content of the entire material is always much higher than the elastomer content after vulcanization. With this strategy, even after vulcanization, the material can still melt at high temperatures and has good fluidity, avoiding the problem of polypropylene being difficult to reprocess after vulcanization with ordinary vulcanizers.

[0071] 5. The present invention can significantly reduce the amount of elastomer while achieving better low-temperature impact performance, significantly increase the tensile strength of the material, and achieve a good balance between material strength and toughness. For example, when only about 28% by mass of elastomer is used in Example 1, the T bd Drop to -40℃, its notched impact strength at -30℃ is about 50kJ / m 2 Due to the reduction in the amount of elastomer used and the use of vulcanization to strengthen the EPDM rubber, the final room temperature tensile strength of the material can reach up to 30MPa. DETAILED DESCRIPTION

[0072] The technical solution of the present invention is further described in detail below in conjunction with the embodiments, but the protection scope of the present invention is not limited thereto.

[0073] In the embodiments of the present invention, the polypropylene used is isotactic polypropylene. However, the type of polypropylene does not limit the present invention, and all types of polypropylene are applicable to the present invention.

[0074] The octylphenol formaldehyde vulcanized resin used in the embodiment is HY-2045 produced by Shanxi Chemical Research Institute, with a hydroxymethyl content of 10-14%. Other commercially available octylphenol formaldehyde vulcanized resins are also suitable for the present invention.

[0075] Example 1

[0076] 80 parts by weight of polypropylene, 20 parts by weight of EPDM, 10 parts by weight of SEP and 0.25 parts by weight of antioxidant 1010 are fed into the main feeding port of the twin-screw extruder according to metering; 0.25 parts by weight of stearic acid, 0.5 parts by weight of zinc oxide and 0.08 parts by weight of stannous chloride are fed into the secondary feeding port of the twin-screw extruder according to metering, and the secondary feeding port is separated from the main feeding port by 3 sections of barrels, and the secondary feeding port is located in the melting section. 0.8 parts by weight of octylphenol formaldehyde vulcanized resin is fed into the third feeding port after the secondary feeding port according to metering, and the feeding port is located in the melting section and is separated from the secondary feeding port by 3 sections of barrels. A low-temperature resistant and high-impact polypropylene alloy is obtained by one-time extrusion. The extrusion conditions were as follows: the main feed port temperature was 90°C, the barrel temperature between the main feed port and the secondary feed port was 180°C, the barrel temperature between the secondary feed port and the third feed port was 200°C, the barrel temperature after the third feed port was 200°C, the die temperature was 200°C, and the screw speed was 80rpm.

[0077] Embodiment 2:

[0078] 80 parts by weight of polypropylene, 20 parts by weight of ethylene-propylene rubber, 10 parts by weight of SEP and 0.25 parts by weight of antioxidant 1010 are fed into the main feeding port of the twin-screw extruder according to metering; 0.25 parts by weight of stearic acid, 0.5 parts by weight of zinc oxide and 0.16 parts by weight of stannous chloride are fed into the secondary feeding port of the twin-screw extruder according to metering, and the secondary feeding port is separated from the main feeding port by 3 sections of the barrel. 1.6 parts by weight of octylphenol formaldehyde vulcanized resin is fed into the third feeding port after the secondary feeding port according to metering, and the feeding port is separated from the secondary feeding port by 3 sections of the barrel. A low-temperature resistant and high-impact polypropylene alloy is obtained by one-time extrusion. The extrusion conditions were as follows: the main feed port temperature was 90°C, the barrel temperature between the main feed port and the secondary feed port was 180°C, the barrel temperature between the secondary feed port and the third feed port was 200°C, the barrel temperature after the third feed port was 200°C, the die temperature was 200°C, and the screw speed was 80rpm.

[0079] Embodiment 3:

[0080] 75 parts by weight of polypropylene, 25 parts by weight of ethylene-propylene rubber, 8 parts by weight of SEP and 0.25 parts by weight of antioxidant 1010 are fed into the main feeding port of the twin-screw extruder according to metering; 0.3125 parts by weight of stearic acid, 0.625 parts by weight of zinc oxide and 0.15 parts by weight of stannous chloride are fed into the secondary feeding port of the twin-screw extruder according to metering, and the secondary feeding port is separated from the main feeding port by 3 sections of the barrel. 1.5 parts by weight of octylphenol formaldehyde vulcanized resin is fed into the third feeding port after the secondary feeding port according to metering, and the feeding port is separated from the secondary feeding port by 3 sections of the barrel. A low-temperature resistant and high-impact polypropylene alloy is obtained by one-time extrusion. The extrusion conditions were as follows: the main feed port temperature was 90°C, the barrel temperature between the main feed port and the secondary feed port was 180°C, the barrel temperature between the secondary feed port and the third feed port was 200°C, the barrel temperature after the third feed port was 200°C, the die temperature was 200°C, and the screw speed was 80rpm.

[0081] Embodiment 4:

[0082] 85 parts by weight of polypropylene, 15 parts by weight of ethylene-propylene rubber, 15 parts by weight of SEP and 0.25 parts by weight of antioxidant 1010 are fed into the main feeding port of the twin-screw extruder according to metering; 0.1875 parts by weight of stearic acid, 0.375 parts by weight of zinc oxide and 0.15 parts by weight of stannous chloride are fed into the secondary feeding port of the twin-screw extruder according to metering, and the secondary feeding port is separated from the main feeding port by 3 sections of the barrel. 1.5 parts by weight of octylphenol formaldehyde vulcanized resin is fed into the third feeding port after the secondary feeding port according to metering, and the feeding port is separated from the secondary feeding port by 3 sections of the barrel. A low-temperature resistant and high-impact polypropylene alloy is obtained by one-time extrusion. The extrusion conditions were as follows: the main feed port temperature was 90°C, the barrel temperature between the main feed port and the secondary feed port was 180°C, the barrel temperature between the secondary feed port and the third feed port was 200°C, the barrel temperature after the third feed port was 200°C, the die temperature was 200°C, and the screw speed was 80rpm.

[0083] Embodiment 5:

[0084] 80 parts by weight of polypropylene, 20 parts by weight of EPDM, 10 parts by weight of SEPS and 0.25 parts by weight of antioxidant 1010 are fed into the main feeding port of the twin-screw extruder according to metering; 0.25 parts by weight of stearic acid, 0.5 parts by weight of zinc oxide and 0.12 parts by weight of stannous chloride are fed into the secondary feeding port of the twin-screw extruder according to metering, and the secondary feeding port is separated from the main feeding port by 3 sections of barrels, and the secondary feeding port is located in the melting section. 1.2 parts by weight of octylphenol formaldehyde vulcanized resin is fed into the third feeding port after the secondary feeding port according to metering, and the feeding port is located in the melting section and is separated from the secondary feeding port by 3 sections of barrels. A low-temperature resistant and high-impact polypropylene alloy is obtained by one-time extrusion. The extrusion conditions were as follows: the main feed port temperature was 90°C, the barrel temperature between the main feed port and the secondary feed port was 180°C, the barrel temperature between the secondary feed port and the third feed port was 200°C, the barrel temperature after the third feed port was 200°C, the die temperature was 200°C, and the screw speed was 80rpm.

[0085] The material properties obtained in the above examples 1 to 5 are shown in Table 1 below:

[0086] Table 1:

[0087]

[0088]

[0089] From the melt index of each embodiment in Table 1, it can be seen that the low temperature resistant high impact resistant polypropylene alloy prepared by the present invention has good processability. The melt index of each embodiment meets the requirements of general extrusion processing for polymer melt index.

[0090] Further compared with patent CN 113912948A, the material prepared by the technical solution of the present invention has a significantly higher tensile strength than patent CN 113912948 A (about 24MPa), and does not need to use expensive fumed silica, which greatly reduces the material cost. At the same time, the material prepared by the technical solution of the present invention has excellent low-temperature toughness, and a good balance between material strength and toughness is achieved. In addition, by using phenolic resin as the vulcanization system, the high-temperature degradation of the matrix PP can be avoided, and the material has better secondary processing performance. The material prepared by the present invention has better tensile properties and impact properties than the material prepared in the comparative patent.

[0091] Compared with the method disclosed in Polymer 112 (2017) 318-324 of using EPDM and SEP to jointly toughen PP, the present invention replaces the saturated EPDM with unsaturated EPDM, thereby introducing a vulcanization system to dynamically vulcanize the EPDM. As a result, the amount of elastomer can be greatly reduced while achieving better low-temperature impact performance, and the tensile strength of the material can be significantly increased. In Polymer 112 (2017) 318-324, an elastomer of up to 44% by mass is required to lower the brittle-to-ductile transition temperature (T bd ) drops to -30°C, and its notched impact strength at -30°C is about 20 kJ / m 2 , the room temperature tensile strength is about 9MPa. However, the present invention replaces EPDM with EPDM and vulcanizes EPDM with phenolic resin. In Example 1, when only about 28% of the mass percentage of the elastomer is used, the T of PP can be reduced. bd Drop to -40℃, its notched impact strength at -30℃ is about 50kJ / m 2 Due to the reduction in the amount of elastomer used and the use of vulcanization to strengthen the EPDM rubber, the final room temperature tensile strength of the material can reach up to 30MPa, achieving a good balance between the toughness and strength of the material.

Claims

1. A dynamically vulcanized low temperature resistant high impact resistant polypropylene alloy, characterized in that The dynamically vulcanized low temperature resistant high impact resistant polypropylene alloy comprises the following components in parts by weight: Polypropylene: 70~90 parts by weight EPDM: 15-25 parts by weight Thermoplastic elastomer: 8-15 parts by weight Octylphenol formaldehyde vulcanized resin: 0.1~3 parts by weight Stannous chloride: 0.008~0.36 parts by weight Zinc oxide: 0.1~0.75 parts by weight Stearic acid: 0.05-0.375 parts by weight; The thermoplastic elastomer is one or both of styrene-hydrogenated isoprene copolymer and styrene-hydrogenated isoprene-styrene copolymer.

2. The dynamically vulcanized low temperature resistant high impact resistant polypropylene alloy according to claim 1, characterized in that The mass content of hydroxymethyl active groups in the octylphenol formaldehyde vulcanized resin is 5-20%.

3. The dynamically vulcanized low temperature resistant high impact resistant polypropylene alloy according to claim 1, characterized in that The low temperature resistant and high impact resistant polypropylene alloy further contains an antioxidant. The dynamically vulcanized low temperature resistant and high impact resistant polypropylene alloy comprises the following components in parts by weight: Polypropylene: 70~90 parts by weight EPDM: 15-25 parts by weight Thermoplastic elastomer: 8-15 parts by weight Octylphenol formaldehyde vulcanized resin: 0.1~3 parts by weight Stannous chloride: 0.008~0.36 parts by weight Zinc oxide: 0.1~0.75 parts by weight Stearic acid: 0.05~0.375 parts by weight Antioxidant: 0.01~5 parts by weight.

4. The dynamically vulcanized low temperature resistant high impact resistant polypropylene alloy as claimed in claim 3, characterized in that The low temperature resistant and high impact resistant polypropylene alloy is composed of the following components in parts by weight: Polypropylene: 70~90 parts by weight EPDM: 15-25 parts by weight Thermoplastic elastomer: 8-15 parts by weight Octylphenol formaldehyde vulcanized resin: 0.1~3 parts by weight Stannous chloride: 0.008~0.36 parts by weight Zinc oxide: 0.1~0.75 parts by weight Stearic acid: 0.05~0.375 parts by weight Antioxidant: 0.01~5 parts by weight.

5. The dynamically vulcanized low temperature resistant high impact resistant polypropylene alloy as claimed in claim 3, characterized in that The low temperature resistant and high impact resistant polypropylene alloy is composed of the following components in parts by weight: Polypropylene: 75~85 parts by weight EPDM: 15-25 parts by weight Thermoplastic elastomer: 8-15 parts by weight Octylphenol formaldehyde vulcanized resin: 0.5~2 parts by weight Stannous chloride: 0.05~0.2 parts by weight Zinc oxide: 0.3~0.7 parts by weight Stearic acid: 0.15~0.35 parts by weight Antioxidant: 0.05~2 parts by weight.

6. The dynamically vulcanized low temperature resistant high impact resistant polypropylene alloy according to any one of claims 1 to 5, characterized in that The amount of the octylphenolic vulcanized resin is 2-12% of the mass of the EPDM rubber; The amount of stannous chloride used is 8-12% of the mass of the octylphenol-formaldehyde resin; The amount of zinc oxide used is 2-3% of the mass of EPDM rubber; The amount of stearic acid used is 1-1.5% of the mass of the EPDM rubber.

7. The method for preparing the dynamically vulcanized low temperature resistant high impact resistant polypropylene alloy according to any one of claims 1 to 5, characterized in that The method is a step-by-step method, comprising the following steps: (1) According to the raw material ratio, polypropylene, ethylene propylene rubber, thermoplastic elastomer, part of stearic acid, part of zinc oxide, part of stannous chloride, and part of antioxidant are added, and melt blended by an internal mixer or melt extruded and granulated by a twin-screw extruder to obtain an intermediate material; (2) The intermediate material, the remaining stearic acid, the remaining zinc oxide, the remaining stannous chloride, and the remaining antioxidant are melt-extruded and granulated by a twin-screw extruder, and octylphenolformaldehyde vulcanized resin is added to the melting section of the twin-screw extruder for dynamic vulcanization, and extruded and granulated to obtain a low-temperature resistant and high-impact resistant polypropylene alloy.

8. The method according to claim 7, characterized in that In the step (1), the amount of the added part of stearic acid, the part of zinc oxide, the part of stannous chloride, and the part of antioxidant is 50-100% of the total amount of stearic acid, the total amount of zinc oxide, the total amount of stannous chloride, and the total amount of antioxidant, respectively, and the remaining amount of stearic acid, the remaining amount of zinc oxide, the remaining amount of stannous chloride, and the remaining amount of antioxidant are added in step (2); The temperature of the internal mixer for melt blending in step (1) is 140-230°C, and the temperature of the twin-screw extruder for melt extrusion granulation is 140-230°C.

9. The method for preparing a dynamically vulcanized low temperature resistant high impact resistant polypropylene alloy according to any one of claims 1 to 5, characterized in that The method is a single-step method: For a twin-screw extruder equipped with a separate metering feeding system and capable of segmented feeding, the steps of the single-step method are as follows: Polypropylene, EPDM rubber and thermoplastic elastomer are fed into the main feeding port of the twin-screw extruder according to metering; stearic acid, zinc oxide and stannous chloride are fed into the main feeding port of the twin-screw extruder according to metering or from a secondary feeding port which is at least one barrel section away from the main feeding port; stearic acid, zinc oxide and stannous chloride can be fed from the same secondary feeding port, or respectively from 2 to 3 secondary feeding ports, and at least one barrel section is separated between two adjacent secondary feeding ports; octylphenol formaldehyde vulcanized resin is fed into the third feeding port arranged in the melting section or the homogenizing section according to metering; the third feeding port and the last secondary feeding port are separated by at least two barrel sections; when an antioxidant is used, the antioxidant can be fed from any feeding port; finally, a low-temperature resistant and high-impact polypropylene alloy is obtained through one-time extrusion.

10. Use of the dynamically vulcanized low-temperature-resistant and high-impact polypropylene alloy according to any one of claims 1 to 5 in the preparation of automobile bumpers, washing machine liner, and refrigerator lining materials.

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