A low temperature resistant and high impact resistant PP-R composite material and preparation method thereof

Abstract

The present invention discloses a low-temperature-resistant and highly impact-resistant PP-R composite material, comprising the following components in parts by weight: random copolymer polypropylene: 70-98 parts by weight; elastomer modifier: 2-30 parts by weight; nanofiller: 1-20 parts by weight; the elastomer modifier is a compound of a first elastomer and a second elastomer, and the mass ratio of the first elastomer to the second elastomer is ≥1.2; the first elastomer is ethylene-propylene diene rubber or ethylene-propylene diene rubber, and the second elastomer is polyisoprene rubber or natural rubber. The present invention also discloses the low-temperature-resistant and highly impact-resistant PP-R composite material and its application in preparing low-temperature-resistant PP-R pipes. The present invention adopts two elastomers as compound toughening modifiers, which can significantly improve the low-temperature (<-5°C) toughness of the material, and the notched impact strength at -30°C can reach 40kJ / m 2 Moreover, under the same low-temperature toughness, the amount of elastomer and nanofiller used is significantly reduced compared with the prior art, thereby reducing costs. The material of the present invention can achieve a more ideal balance of rigidity and toughness at low temperatures.

Description

Technical Field

[0001] The invention relates to a low-temperature-resistant and high-impact PP-R composite material and a preparation method thereof. Background Art

[0002] Random copolymer polypropylene (PP-R) is widely used in the manufacture of household pipes. Compared to traditional galvanized pipes, PP-R pipes offer advantages such as corrosion resistance, low cost, and easy installation. PP-R pipes are also more resistant to high temperatures than polyethylene (PE) pipes, more resilient than homopolymer polypropylene (PP-H) pipes, and have a longer service life than segmented copolymer polypropylene (PP-B) pipes. Therefore, PP-R pipes have become the mainstream product for residential hot and cold water supply pipes. Because the material's molecular chain contains a small amount of randomly sequenced ethylene structures, PP-R pipes exhibit good toughness at room temperature, greatly facilitating their transportation and installation.

[0003] However, the performance of polymer materials will be affected by the ambient temperature. For PP-R materials, when the ambient temperature drops, its toughness will drop sharply. When the ambient temperature is below 0°C, PP-R exhibits a typical brittle fracture phenomenon, which makes PP-R pipes prone to pipe bursts in cold climates. At the same time, they are also more susceptible to damage during transportation and storage, greatly limiting the application scenarios and geographical scope of PP-R pipes. Therefore, improving the low-temperature toughness of PP-R and preparing low-temperature impact-resistant (high-impact) PP-R materials are technical difficulties that must be solved in the development of high-performance PP-R pipes.

[0004] Existing toughening and modification technologies for PP-R pipes often only improve the material's impact resistance at temperatures above -5°C. Improvements at lower temperatures are insignificant and can complicate the production process for PP-R pipes. For example, patent CN 112175293 A uses a β-nucleating agent to toughen PP-R pipes, requiring high-temperature annealing of the extruded pipe.

[0005] CN 113912948 A discloses a polypropylene nanocomposite material with low-temperature toughness and a balanced stiffness-toughness, and its preparation method. This method achieves low-temperature toughness by synergizing an elastomer with nanosilica, combined with dynamic vulcanization technology. The material exhibits excellent low-temperature toughness at ultra-low temperatures (-30°C). However, for materials not subjected to dynamic vulcanization and crosslinking, low-temperature performance is mediocre. For example, Examples 2 and 3 of the patent exhibit poor low-temperature notched impact strength at -30°C.

[0006] It should be noted that the dynamic vulcanization cross-linking method described in CN 113912948 A has inherent technical drawbacks: the cross-linked polymer material cannot be remelted for secondary processing due to its already cross-linked structure, resulting in a single molding cycle, which is not conducive to subsequent processing. Furthermore, the molded product cannot be recycled or reused. This cross-linked material has significant limitations and cannot be recycled, which also violates environmental protection requirements.

[0007] Therefore, the existing technical problem is how to perform low-temperature toughening modification on PP-R materials without cross-linking, facilitating secondary processing while maintaining its rigidity. In addition, the process must be simple and feasible, without the need for post-processing. Summary of the Invention

[0008] The purpose of the present invention is to provide a low-temperature-resistant and high-impact PP-R composite material and a production and preparation technology thereof.

[0009] The technical solution adopted in the present invention is:

[0010] A low-temperature-resistant and high-impact PP-R composite material, comprising the following components in parts by weight:

[0011] Random copolymer polypropylene (PP-R): 70-98 parts by weight

[0012] Elastomer modifier: 2-30 parts by weight

[0013] Nanofiller: 1-20 parts by weight.

[0014] The melt index of the random copolymer polypropylene (PP-R) is 0.1-30 g / 10 min, 230°C / 2.16 kg, preferably 0.1-5 g / 10 min, 230°C / 2.16 kg; more preferably 0.1-0.5 g / 10 min, 230°C / 2.16 kg.

[0015] The elastomer modifier is a compound of a first elastomer and a second elastomer, and the mass ratio of the first elastomer to the second elastomer is ≥1.2; the first elastomer is preferably EPDM rubber or EPDM ternary rubber, and the second elastomer is preferably polyisoprene rubber or natural rubber.

[0016] Furthermore, in the elastomer modifier, the mass content of the second elastomer is 1-45.5% of the mass of the elastomer modifier, and preferably the mass content of the second elastomer is 10-30% of the mass of the elastomer modifier.

[0017] The nano filler is fumed silica or nano montmorillonite with a specific surface area of ​​50-800m 2 / g.

[0018] The nanofiller is preferably hydrophobic fumed silica, more preferably with a specific surface area of ​​100-300 m 2 / g of hydrophobic fumed silica.

[0019] The gas-phase nano-silica has a dendritic structure.

[0020] The nano-montmorillonite has a layered structure.

[0021] Furthermore, the low-temperature-resistant and high-impact PP-R composite material also contains an antioxidant. The material includes the following components in parts by weight:

[0022] Random copolymer polypropylene (PP-R): 70-98 parts by weight

[0023] Elastomer modifier: 2-30 parts by weight

[0024] Nanofiller: 1-20 parts by weight

[0025] Antioxidant: 0.01-5 parts by weight.

[0026] Furthermore, the low-temperature-resistant and high-impact PP-R composite material is preferably composed of the following components in parts by weight:

[0027] Random copolymer polypropylene (PP-R): 70-95 parts by weight

[0028] Elastomer modifier: 5-25 parts by weight

[0029] Nanofiller: 2-18 parts by weight

[0030] Antioxidant: 0.05-2 parts by weight.

[0031] Furthermore, the low temperature resistant and high impact resistant PP-R composite material is preferably composed of the following components in parts by weight:

[0032] Random copolymer polypropylene (PP-R): 75-90 parts by weight

[0033] Elastomer modifier: 10-25 parts by weight

[0034] Nanofiller: 5-15 parts by weight

[0035] Antioxidant: 0.1-1 parts by weight.

[0036] Furthermore, the low temperature resistant and high impact resistant PP-R composite material is preferably composed of the following components in parts by weight:

[0037] Random copolymer polypropylene (PP-R): 75-80 parts by weight

[0038] Elastomer modifier: 20-25 parts by weight

[0039] Nanofiller: 5-10 parts by weight

[0040] Antioxidant: 0.1-1 parts by weight.

[0041] The antioxidant is preferably one of antioxidant 1010 and antioxidant 1076, or a mixture of both.

[0042] The present invention also provides a method for preparing the low-temperature-resistant and high-impact PP-R composite material, which is the following method (1) or method (2):

[0043] Method (1) Step-by-step method, which includes two steps:

[0044] (1) taking the raw materials according to the raw material ratio, mixing the nano filler, part of the elastomer modifier, and part of the antioxidant uniformly, and melt-extruding the obtained mixture in a twin-screw extruder to obtain an intermediate material;

[0045] (2) All the intermediate materials obtained in the above step, random copolymerized polypropylene, the remaining elastomer modifier, and the remaining antioxidant are mixed uniformly, and the resulting mixture is fed into a twin-screw extruder for melt extrusion and granulation to obtain the low-temperature resistant and high-impact PP-R composite material.

[0046] Furthermore, in the step (1), the amount of the partially added elastomer modifier is preferably 50 to 100% of the total amount of the elastomer modifier, and the remaining amount of the elastomer modifier is added in the step (2);

[0047] Furthermore, in the step (1), the amount of the partial antioxidant added is preferably 50-100% of the total amount of the antioxidant, and the remaining amount of the antioxidant is added in the step (2).

[0048] When the amount of the elastomer modifier added in step (1) is 100% of the total amount of the elastomer modifier, it means that all the elastomer modifier is added in step (1) and no more elastomer modifier needs to be added in step (2).

[0049] When the amount of antioxidant added in step (1) is 100% of the total amount of antioxidant, it means that all the antioxidant is added in step (1) and no more antioxidant needs to be added in step (2).

[0050] In the step (1) or step (2), the mixing is preferably carried out by using a high-speed mixing stirrer.

[0051] In the step (1) or (2), the melt extrusion granulation process can be the random copolymer polypropylene extrusion granulation process commonly used in the industry, and the extrusion granulation is generally performed at a temperature of 140-230°C.

[0052] Furthermore, the typical extrusion process is preferably as follows: conveying section temperature 90-140°C, melting section temperature 140-230°C (preferably 160-220°C), homogenizing section temperature 160-230°C (preferably 200-220°C), die temperature 160-230°C (preferably 200-220°C), and screw speed 100-150rpm.

[0053] The melt extrusion granulation process of step (1) or (2) can be the same or different, and can be within the above range. The extrusion process of step (2) is carried out according to the PP-R extrusion process commonly used in the industry, while the extrusion temperature of step (1) can be appropriately lowered because PP-R is not included.

[0054] Method (2) Single-step method:

[0055] For twin-screw extruders equipped with a separate metering feeding system and capable of segmented feeding, there is no need to use a high-speed mixer to mix the raw materials, nor is there a need for a step-by-step method. The steps of the single-step method are as follows:

[0056] The elastomer modifier, nanofiller and antioxidant are fed into the main feeding port through the metering system of the twin-screw extruder, and the random copolymer polypropylene is fed into the secondary feeding port through the metering system, wherein the secondary feeding port is separated from the main feeding port by at least 2 barrel sections. Finally, a low-temperature-resistant and high-impact PP-R composite material is obtained through one extrusion.

[0057] The melt extrusion process can be carried out under the commonly used random copolymer polypropylene extrusion granulation conditions in the industry, generally at a temperature of 140-230°C.

[0058] Furthermore, a typical extrusion process is preferably as follows: 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 100-150 rpm.

[0059] The low-temperature-resistant and high-impact-resistant PP-R composite material provided by the present invention can be used to prepare low-temperature-resistant PP-R pipes.

[0060] The beneficial effects of the present invention are:

[0061] 1. Introducing polyisoprene rubber or natural rubber as a second elastomer into a traditional single elastomer toughening agent, while controlling the ratio of the first elastomer content to the second elastomer content to be greater than 1.2. Furthermore, through appropriate processing, the majority of the first elastomer and the majority of the second elastomer are mixed before the random copolymer polypropylene, thereby allowing the second elastomer, which contains a smaller total content, to be distributed within the first elastomer. The advantage of this technology is that polyisoprene rubber or natural rubber has much stronger internal friction relaxation than EPDM or EPDM rubber, and its glass transition temperature is significantly lower than that of EPDM or EPDM rubber. Therefore, the energy dissipation process of the second elastomer at low temperatures is more significant than that of the first elastomer. However, because the compatibility of polyisoprene rubber or natural rubber with random copolymer polypropylene is significantly worse than that of EPDM or EPDM rubber, using the second elastomer alone to toughen random copolymer polypropylene does not achieve satisfactory results. By first mixing a small amount of the second elastomer with the first elastomer and then blending it with the random copolymer polypropylene, the second elastomer is distributed as much as possible within the first elastomer, ensuring that the second elastomer does not come into direct contact with the random copolymer polypropylene, thereby achieving good compatibility between the elastomer and the matrix. This allows the second elastomer to experience more significant internal friction relaxation at low temperatures, allowing the material to dissipate more energy when impacted at low temperatures, significantly improving its low-temperature toughness.

[0062] 2. Introducing dendritic fumed silica or layered nano-montmorillonite as modifiers, and through a special preparation process, confining the nanofiller within the elastomer domain. On the one hand, the addition of the nanofiller significantly inhibits the coarsening of the elastomer phase, thereby achieving better dispersion of the elastomer in the PP-R. On the other hand, compared to ordinary fillers, fumed silica and nano-montmorillonite both have a large specific surface area, forming a particle network that penetrates the elastomer domain. This particle network not only ensures greater rigidity of the material, but also absorbs additional energy during the destruction process of the particle network during impact, significantly improving the material's overall performance.

[0063] 3. The present invention does not add a nucleating agent, so the composite material is used to produce PP-R pipes without post-processing, and the low-temperature resistant PP-R pipes produced do not undergo cross-linking and vulcanization, and can be repeatedly melt-processed, thereby improving processing performance, which is beneficial to downstream manufacturers' reprocessing and recycling after use.

[0064] Compared with the traditional method of using a single elastomer to toughen PP-R, the present invention uses two elastomers as a compound toughening modifier, which can significantly improve the low-temperature (<-5°C) toughness of the material, and the notched impact strength at -30°C can reach 40kJ / m 2Furthermore, while maintaining the same low-temperature toughness, the amount of elastomer and nanofiller used is significantly reduced compared to existing technologies, reducing costs. Furthermore, compared to traditional single-elastomer toughening materials, the introduction of nanofillers in this invention ensures that the material's rigidity is not compromised by the addition of the second elastomer. The tensile strength is similar to that of the pre-modified material, achieving a more ideal balance of rigidity and toughness at low temperatures. DETAILED DESCRIPTION

[0065] The technical solution of the present invention is further described in detail below with reference to the embodiments, but the protection scope of the present invention is not limited thereto.

[0066] The nanofiller used in the embodiment of the present invention is hydrophobic fumed silica, the specific model is R974 (Evonik Degussa), with a specific surface area of ​​180m 2 / g.

[0067] The random copolymer polypropylene (PP-R) used in the examples has a melt index of 0.3 g / 10 min, 230° C. / 2.16 kg.

[0068] Example 1

[0069] 25 parts by weight of an elastomer modifier (the first elastomer is ethylene propylene diene rubber (EPDM) and the second elastomer is polyisoprene rubber (polyisoprene rubber; the mass ratio of the first elastomer to the second elastomer is 8:2), 10 parts by weight of a nanofiller, and 0.5 parts by weight of an antioxidant 1010 were mixed uniformly in a high-speed mixer. The resulting mixture was fed into a twin-screw extruder for melt extrusion and granulation to obtain an intermediate material. All the intermediate materials obtained were mixed uniformly with 75 parts by weight of a random copolymer polypropylene in a high-speed mixer, and the mixture was then fed into a twin-screw extruder for melt extrusion and granulation to obtain the final low-temperature-resistant and impact-resistant PP-R composite material. Extrusion conditions were: a conveying section temperature of 90°C, a melting section temperature of 160°C, a homogenizing section temperature of 200°C, a die temperature of 200°C, and a screw speed of 100 rpm.

[0070] Example 2:

[0071] Using a twin-screw extruder equipped with a separate metering feeding system and capable of two-stage feeding, 20 parts by weight of an elastomer modifier (the first elastomer is EPDM, the second elastomer is natural rubber; the mass ratio of the first to the second elastomer is 7:3), 5 parts by weight of a nanofiller, and 0.2 parts by weight of antioxidant 1010 were fed into the main feed port through the metering system. Separately, 80 parts by weight of a random copolymer of polypropylene was fed into the secondary feed port through the metering system, separated from the main feed port by three barrel sections. A low-temperature-resistant and impact-resistant PP-R composite material was obtained through a single extrusion process. Extrusion conditions were a conveying section temperature of 180°C, a melting section temperature of 220°C, a homogenizing section temperature of 220°C, a die temperature of 220°C, and a screw speed of 150 rpm.

[0072] Example 3:

[0073] 15 parts by weight of an elastomer modifier (the first elastomer is ethylene propylene diene monomer (EPDM) rubber, the second elastomer is polyisoprene rubber (POI) rubber; the mass ratio of the first to the second elastomer is 9:1), 15 parts by weight of a nanofiller, and 0.5 parts by weight of antioxidant 1076 were mixed uniformly in a high-speed mixer. The resulting mixture was fed into a twin-screw extruder for melt extrusion and granulation to obtain an intermediate material. All the intermediate materials obtained were mixed uniformly with 85 parts by weight of random copolymer polypropylene in a high-speed mixer, and then fed into a twin-screw extruder for melt extrusion and granulation to obtain the final low-temperature-resistant and impact-resistant PP-R composite material. Extrusion conditions were: a conveying section temperature of 90°C, a melting section temperature of 160°C, a homogenizing section temperature of 200°C, a die temperature of 200°C, and a screw speed of 100 rpm.

[0074] Example 4:

[0075] Using a twin-screw extruder equipped with a separate metering feeding system and capable of two-stage feeding, 10 parts by weight of an elastomer modifier (the first elastomer is EPDM, the second elastomer is natural rubber; the mass ratio of the first to the second elastomer is 7:3), 15 parts by weight of a nanofiller, and 0.2 parts by weight of antioxidant 1076 were fed into the main feed port through the metering system. Separately, 90 parts by weight of a random copolymer polypropylene was fed into the secondary feed port through the metering system, separated from the main feed port by three barrel sections. A low-temperature-resistant and impact-resistant PP-R composite material was obtained through a single extrusion process. Extrusion conditions were a conveying temperature of 180°C, a melting temperature of 220°C, a homogenizing temperature of 220°C, a die temperature of 220°C, and a screw speed of 150 rpm.

[0076] Comparative Example 1

[0077] Commercially available PP-R is not modified.

[0078] Comparative Example 2

[0079] 75 parts by weight of random copolymer polypropylene, 25 parts by weight of elastomer modifier (the elastomer is ethylene propylene diene rubber), and 0.5 parts by weight of antioxidant 1010 were mixed uniformly in a high-speed mixer. The resulting mixture was fed into a twin-screw extruder for melt extrusion and granulation to obtain a modified PP-R material. Extrusion conditions were: a conveying section temperature of 90°C, a melting section temperature of 160°C, a homogenizing section temperature of 200°C, a die temperature of 200°C, and a screw speed of 100 rpm.

[0080] Comparative Example 3

[0081] 75 parts by weight of random copolymer polypropylene, 25 parts by weight of elastomer modifier (polyisoprene rubber), and 0.5 parts by weight of antioxidant 1010 were mixed uniformly in a high-speed mixer. The resulting mixture was fed into a twin-screw extruder for melt extrusion and granulation to obtain a modified PP-R material. Extrusion conditions were: a conveying section temperature of 90°C, a melting section temperature of 160°C, a homogenizing section temperature of 200°C, a die temperature of 200°C, and a screw speed of 100 rpm.

[0082] The properties of the materials obtained in the above examples and comparative examples are shown in Table 1 below:

[0083] Table 1:

[0084]

[0085] Further compared with patent CN 113912948 A, Examples 2 and 3 in patent CN 113912948 A require the addition of an elastomer with a mass fraction of about 20%, resulting in a lower tensile strength of the material (about 24 MPa) than Examples 3 and 4 in the present invention, and the higher amount of elastomer added increases the material cost. While meeting the low-temperature toughness similar to Examples 2 and 3 in the comparative documents, Examples 3 and 4 in the present invention can reduce the mass fraction of the elastomer added from about 20% to about 10%, which not only improves the tensile strength of the material, but also significantly reduces the material cost. On the other hand, Example 1 in patent CN 113912948 A requires the addition of an elastomer with a mass fraction of 20% and a mass fraction of 19% of nano-silica, while Example 2 in the present invention meets the low-temperature toughness similar to Example 1 in the comparative document, while reducing the added mass fraction of fumed silica to about 5%, significantly reducing the material cost, and the tensile strength is higher than Example 1 in the comparative document (about 24 MPa).

[0086] Comparative Example 4

[0087] Compare the differences in the effects of fumed silica and other fillers such as calcium carbonate on the final material properties. The fumed silica in Example 1 was replaced with calcium carbonate with a particle size of 1250 mesh. The performance comparison is shown in Table 2 below:

[0088] Table 2

[0089]

[0090]

[0091] It can be seen that ordinary fillers have limited effect on improving the low-temperature toughness of PP-R, and the impact strength below -20°C is still poor, not as good as the fumed silica used in this application.

[0092] Comparative Example 5

[0093] Comparison of the performance differences between the one-pot method and the step-by-step method. All the raw materials in Example 1 were mixed in a high-speed mixer and fed into a twin-screw extruder for extrusion to obtain Comparative Example 5 (one-pot method). The performance of Comparative Example 5 (one-pot method) was compared with that of Example 1 as shown in Table 3.

[0094] Table 3

[0095]

[0096] The results show that the differences between the one-pot and step-by-step processes lead to significant differences in the low-temperature toughness of the materials. This is because the step-by-step method first mixes the second elastomer with the first elastomer without adding random copolymer polypropylene. This allows the second elastomer to be distributed as much as possible within the first elastomer, ensuring that it does not come into direct contact with the random copolymer polypropylene, thereby achieving good compatibility between the elastomer and the matrix. The mixed elastomer modifier is then extruded with polypropylene, leveraging the second elastomer's more pronounced internal friction relaxation at low temperatures to dissipate more energy when impacted at low temperatures, significantly improving the material's low-temperature toughness.

[0097] However, the one-pot rule will cause the second elastomer to come into direct contact with the polypropylene matrix, resulting in poor compatibility and the elastomer being unable to fully function, resulting in limited improvement in the material's low-temperature toughness.

Claims

1. A low temperature resistant and high impact resistant PP-R composite material, characterized in that The material comprises the following components in parts by weight: Random copolymer polypropylene: 70-98 parts by weight Elastomer modifier: 2-30 parts by weight Nano filler: 1-20 parts by weight; Antioxidant: 0.01-5 parts by weight; The nanofiller is hydrophobic fumed silica with a specific surface area of ​​50-800 m 2 / g; The elastomer modifier is a compound of a first elastomer and a second elastomer, and the mass ratio of the first elastomer to the second elastomer is ≥1.2; the first elastomer is ethylene propylene diene rubber or ethylene propylene diene rubber, and the second elastomer is polyisoprene rubber or natural rubber; The low temperature resistant and high impact resistant PP-R composite material is prepared by the following method (1) or method (2): Method (I) Step-by-step method, including two steps: (1) taking various raw materials according to the raw material ratio, mixing the nano filler, part of the elastomer modifier, and part of the antioxidant uniformly, and melt-extruding and granulating the obtained mixture in a twin-screw extruder to obtain an intermediate material; (2) uniformly mixing all the intermediate materials obtained in the above step, the random copolymer polypropylene, the remaining elastomer modifier, and the remaining antioxidant, and then feeding the obtained mixture into a twin-screw extruder for melt extrusion granulation to obtain the low-temperature resistant and high-impact PP-R composite material; Method (II) Single-step method: Use a twin-screw extruder equipped with a separate metering feeding system and capable of segmented feeding. The steps are: The elastomer modifier, nano filler and antioxidant are fed into the main feeding port through the metering system of the twin-screw extruder, and the random copolymer polypropylene is fed into the secondary feeding port through the metering system, wherein the secondary feeding port is separated from the main feeding port by at least 2 barrel sections, and finally a low-temperature resistant and impact-resistant PP-R composite material is obtained through one extrusion.

2. The low temperature resistant and high impact resistant PP-R composite material according to claim 1, characterized in that In the elastomer modifier, the mass content of the second elastomer is 1-45.5% of the mass of the elastomer modifier.

3. The low temperature resistant and high impact resistant PP-R composite material according to claim 2, characterized in that In the elastomer modifier, the mass content of the second elastomer is 10-30% of the mass of the elastomer modifier.

4. The low temperature resistant and high impact resistant PP-R composite material according to claim 1, characterized in that The melt index of the random copolymer polypropylene is 0.1-30 g / 10 min, 230° C. / 2.16 kg.

5. The method for preparing the low temperature resistant and high impact resistant PP-R composite material according to any one of claims 1 to 4, characterized in that The method is the following method (1) or method (2): Method (I) Step-by-step method, including two steps: (1) taking various raw materials according to the raw material ratio, mixing the nano filler, part of the elastomer modifier, and part of the antioxidant uniformly, and melt-extruding and granulating the obtained mixture in a twin-screw extruder to obtain an intermediate material; (2) uniformly mixing all the intermediate materials obtained in the above step, the random copolymer polypropylene, the remaining elastomer modifier, and the remaining antioxidant, and then feeding the obtained mixture into a twin-screw extruder for melt extrusion granulation to obtain the low-temperature resistant and high-impact PP-R composite material; Method (II) Single-step method: Use a twin-screw extruder equipped with a separate metering feeding system and capable of segmented feeding. The steps are: The elastomer modifier, nano filler and antioxidant are fed into the main feeding port through the metering system of the twin-screw extruder, and the random copolymer polypropylene is fed into the secondary feeding port through the metering system, wherein the secondary feeding port is separated from the main feeding port by at least 2 barrel sections, and finally a low-temperature resistant and impact-resistant PP-R composite material is obtained through one extrusion.

6. The method according to claim 5, characterized in that In step (1) or step (2) of the method (1), extrusion granulation is performed at a temperature of 140-230°C; in the method (2), extrusion granulation is performed at a temperature of 140-230°C.

7. Use of the low-temperature resistant and high-impact PP-R composite material according to any one of claims 1 to 4 in the preparation of low-temperature resistant PP-R pipes.

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