Low-temperature-cracking-resistant PP-R water supply pipe and preparation method thereof

Abstract

The invention discloses a low-temperature-cracking-resistant PP-R water supply pipe and a preparation method thereof, and belongs to the field of pipes. The low-temperature-cracking-resistant PP-R water supply pipe is prepared from the following raw materials in parts by weight: 100 parts of PP-R resin; 4-7 parts of an elastomer; 3.5 to 6 parts of modified toughening particles; the modified toughening particles are formed by grafting long-chain olefine acid on nano inorganic rigid particles and then polymerizing styrene monomers and isoprene monomers, and the mass ratio of the nano inorganic rigid particles to the long-chain olefine acid to the styrene monomers to the isoprene monomers is (10-20): (1-3): (1-2.5): (1.5-3). The PP-R pipe has the advantages that the low-temperature toughness of the PP-R pipe is improved, and meanwhile, the high-temperature creep property is kept at a good level.

Description

Technical Field

[0001] The present application relates to the field of pipes, and in particular to a PP-R water supply pipe resistant to low-temperature cracking and a preparation method thereof. Background Art

[0002] PP-R is a high-performance thermoplastic. Due to its excellent chemical stability and heat resistance, it is often used as a water pipe in building water supply and drainage systems. In addition, due to its long service life, it has gradually become a standard configuration for new residential buildings and public facilities in many countries and regions. However, as the application of PP-R pipes becomes more and more widespread, it is found that PP-R pipes are prone to low-temperature brittle fracture, especially when PP-R pipes are used in cold areas or outdoors in winter, which greatly affects the safe and reliable operation of the water supply system.

[0003] In order to improve the low-temperature toughness of PP-R pipes, elastomer toughening is currently used. The amount of elastomer added is generally 15wt%~30wt%. Elastomers, such as ethylene-octene copolymers, can effectively absorb part of the impact energy and alleviate the crack expansion trend to improve toughness.

[0004] However, the addition of elastomers will cause the high-temperature creep performance of PP-R pipes to be significantly reduced, resulting in the application of PP-R pipes being limited and difficult to use in scenarios with high comprehensive performance requirements. Summary of the invention

[0005] In order to improve the low-temperature toughness of the PP-R pipe while maintaining the high-temperature creep performance at a good level, the present application provides a PP-R water supply pipe resistant to low-temperature cracking and a preparation method thereof.

[0006] In the first aspect, the present application provides a PP-R water supply pipe resistant to low temperature cracking, which adopts the following technical solution: A PP-R water supply pipe resistant to low temperature cracking is prepared from the following raw materials in parts by weight: PP-R resin 100 parts; 4~7 parts of elastomer; 3.5~6 parts of modified toughening particles; The modified toughened particles are formed by grafting long-chain olefinic acid onto nano-inorganic rigid particles and then polymerizing styrene monomer and isoprene monomer. The mass ratio of the nano-inorganic rigid particles, long-chain olefinic acid, styrene monomer and isoprene monomer is (10-20):(1-3):(1-2.5):(1.5-3).

[0007] By adopting the above technical solution, elastomer is added to the PP-R resin, and the elastomer can consume impact energy and control crack development. In addition, modified toughening particles are added. The addition of modified toughening particles can reduce the amount of elastomer used and reduce the impact on the high-temperature creep performance of the pipe.

[0008] The modified toughening particles are modified on the basis of nano inorganic rigid particles. The distribution of nano inorganic rigid particles in the resin can reduce the state of stress concentration. When the pipe is impacted, the internal cracks will be blocked by the nano inorganic rigid particles, making the pipe not easy to crack. Nano inorganic rigid particles are easily affected by dispersion problems such as agglomeration. Therefore, long chain olefinic acid, styrene and isoprene copolymers are polymerized on the surface of nano inorganic rigid particles to reduce the surface energy of nano inorganic rigid particles and promote the dispersion of modified toughening particles. At the same time, the polyolefin structure of the copolymer has better compatibility with the PP-R resin system, improved interface bonding force, and stronger high temperature creep performance. The selection of long chain olefinic acid introduces a certain degree of gap between the copolymer and the nano inorganic rigid particles, which can not only provide the elastomer and PP-R resin for combination, but also when the pipe is impacted, the modified toughening particle structure slides relatively, so that it can maintain sufficient toughness in low temperature environment and is not easy to crack.

[0009] Optionally, the nano inorganic rigid particles are first modified with an amino-containing silane coupling agent and then grafted with a long-chain olefinic acid, and the mass ratio of the nano inorganic rigid particles to the amino-containing silane coupling agent is (10-20):(0.7-2.2).

[0010] By adopting the above technical scheme, amino functional groups are introduced into the nano inorganic rigid particles through modification with an amino silane coupling agent, which not only makes it easier to graft long-chain olefinic acids, but also forms a spatial structure that is easy to slide relatively, thereby improving the low-temperature toughness of the PP-R pipe.

[0011] Optionally, the long-chain olefinic acid includes one or more of 8-nonenoic acid, 10-undecenoic acid and 12-tridecenoic acid.

[0012] By adopting the above technical solution, the above long-chain olefinic acid can provide polymerization sites to achieve the polymerization of styrene-isoprene copolymer on the surface of nano inorganic rigid particles.

[0013] Optionally, the long-chain olefinic acid is a compound of 8-nonenoic acid and 10-undecenoic acid, and the mass ratio of 8-nonenoic acid to 10-undecenoic acid is (1-2):(3-4).

[0014] By adopting the above technical solution, selecting olefinic acid with a suitable chain segment length, and compounding and modifying the staggered surface space structure, it is better compatible with the PP-R resin system, thereby further improving the low-temperature toughness.

[0015] Optionally, the elastomer includes one or more of ethylene-methyl acrylate copolymer, nitrile rubber, ethylene-propylene-diene rubber and ethylene-octene copolymer.

[0016] By adopting the above technical solution, the above elastomer can consume impact energy and control crack development in PP-R resin.

[0017] Optionally, the elastomer is ethylene-methyl acrylate copolymer, and the mass content of methyl acrylate in the ethylene-methyl acrylate copolymer is 25-28%.

[0018] By adopting the above technical solution, the ethylene-methyl acrylate copolymer has good flexibility and crack resistance, and the ethylene-methyl acrylate copolymer with the above methyl acrylate content can be fully compatible with the surface of the modified toughening particles, further improving the dispersibility of the modified toughening particles, thereby improving the low-temperature toughness of the PP-R pipe.

[0019] Optionally, the nano inorganic rigid particles include one or more of nano-scale calcium carbonate, silicon dioxide, titanium dioxide and carbon fibers.

[0020] Optionally, the raw materials also include 0.5 to 3 parts by weight of masterbatch.

[0021] By adopting the above technical solution, PP-R pipes can present various design colors.

[0022] In the second aspect, the present application provides a method for preparing a PP-R water supply pipe resistant to low temperature cracking, which adopts the following technical solution: A method for preparing a PP-R water supply pipe resistant to low temperature cracking comprises the following steps: Premixing PP-R resin, elastomer and modified toughening particles to obtain a premix; The premix is ​​heated, mixed and sheared to be plasticized into a viscous flow state, extruded to form a tube blank, and drawn, cooled and shaped into a water supply pipe.

[0023] Optionally, the method for preparing the modified toughened particles comprises the following steps: The nano inorganic rigid particles are dispersed in a first solvent, an amino-containing silane coupling agent is added and reacted, and after the reaction is completed, the particles are filtered, washed, and dried to obtain pretreated nano inorganic rigid particles; Pre-treated nano inorganic rigid particles are dispersed in a second solvent, long chain olefinic acid is added and reacted, and after the reaction is completed, the particles are filtered, washed and dried to obtain grafted nano inorganic rigid particles; The grafted inorganic nano rigid particles are dispersed in a third solvent, styrene monomer and isoprene monomer are added, and after being mixed evenly, an initiator is added to react. After the reaction is completed, the particles are filtered, washed and dried to obtain modified toughened particles.

[0024] By adopting the above technical solution, the surface grafting and polymerization of nano inorganic rigid particles are achieved in three steps, thereby improving the uniformity and stability of the surface of the modified and toughened particles.

[0025] In summary, this application has the following beneficial effects: 1. The modified toughening particles of the present application are modified on the basis of nano inorganic rigid particles. The distribution of nano inorganic rigid particles in the resin can reduce the state of stress concentration. When the pipe is impacted, the internal cracks will be hindered by the nano inorganic rigid particles, making the pipe not easy to crack. Nano inorganic rigid particles are easily affected by dispersion problems such as agglomeration. Therefore, long chain olefinic acid, styrene and isoprene copolymers are polymerized on the surface of nano inorganic rigid particles to reduce the surface energy of nano inorganic rigid particles and promote the dispersion of modified toughening particles. At the same time, the polyolefin structure of the copolymer has better compatibility with the PP-R resin system, the interface bonding force is improved, and the high temperature creep performance is stronger. The selection of long chain olefinic acid introduces a certain degree of gap between the copolymer and the nano inorganic rigid particles, which can not only provide the elastomer and the PP-R resin for combination, but also when the pipe is impacted, the modified toughening particle structure slides relatively, so that it can maintain sufficient toughness in a low temperature environment and is not easy to crack.

[0026] 2. The present application can select olefinic acid with suitable chain segment length, and compound and modify the staggered surface spatial structure to make it more compatible with the PP-R resin system, thereby further improving the low-temperature toughness. DETAILED DESCRIPTION

[0027] The present application is described in further detail below.

[0028] Preparation Example 1 The preparation method of modified toughened particles comprises the following steps: Weigh 1000g of inorganic nanoparticles, 70g of amino-containing silane coupling agent, 100g of long-chain olefinic acid, 40g of triethylamine, 100g of styrene monomer, 150g of isoprene monomer and 5g of initiator. Separately weigh 5L of the first solvent, the second solvent and the third solvent, each of which is 92wt% ethanol solution, and the third solvent is anhydrous ethanol.

[0029] Specifically, the inorganic nano-particles are nano-calcium carbonate; the amino-containing silane coupling agent is γ-aminopropyltriethoxysilane; the long-chain olefinic acid is 10-undecenoic acid; and the initiator is azobisisobutyronitrile.

[0030] The inorganic nanoparticles are stirred and dispersed in the first solvent, an amino-containing silane coupling agent is added, and the mixture is heated to 50° C. to react for 1.5 hours. After the reaction is completed, the mixture is filtered, washed with an ethanol solution, and dried at 60° C. to obtain pretreated inorganic nanoparticles. The pretreated nano inorganic rigid particles are stirred and dispersed in the second solvent, triethylamine is added to disperse them uniformly, and then long-chain olefinic acid is added, and the mixture is heated to 65° C. to react for 2 hours. After the reaction is completed, the mixture is filtered, washed with ethanol solution, and dried at 60° C. to obtain grafted nano inorganic rigid particles; The grafted nano inorganic rigid particles are stirred and dispersed in a third solvent, and nitrogen is introduced for protection. Styrene monomer and isoprene monomer are added, and after mixing evenly, an initiator solution is added. The initiator solution consists of 0.2L of anhydrous ethanol containing 10wt% of initiator. The particles are heated to 70°C and reacted for 3.5h. After the reaction is completed, the particles are filtered, washed with ethanol solution, and dried at 60°C to obtain modified toughened particles.

[0031] Preparation Example 2 The preparation method of the modified toughened particles is different from that of Preparation Example 1 in that the raw materials are different.

[0032] Weigh 2000 g of nano inorganic rigid particles, 220 g of amino-containing silane coupling agent, 300 g of long-chain olefinic acid, 60 g of triethylamine, 250 g of styrene monomer, 300 g of isoprene monomer and 8 g of initiator.

[0033] Specifically, the inorganic nano-particles are nano-calcium carbonate; the amino-containing silane coupling agent is γ-aminopropyltriethoxysilane; the long-chain olefinic acid is 10-undecenoic acid; and the initiator is azobisisobutyronitrile.

[0034] Preparation Example 3 The preparation method of the modified toughened particles is different from that of Preparation Example 1 in that the raw materials are different.

[0035] Specifically, the long-chain olefinic acid is 8-nonenoic acid.

[0036] Preparation Example 4 The preparation method of the modified toughened particles is different from that of Preparation Example 1 in that the raw materials are different.

[0037] Specifically, the long-chain olefinic acid is a mixture of 8-nonenoic acid and 10-undecenoic acid in a mass ratio of 1:3.

[0038] Preparation Example 5 The preparation method of the modified toughened particles is different from that of Preparation Example 1 in that the raw materials are different.

[0039] Specifically, the long-chain olefinic acid is a mixture of 8-nonenoic acid and 10-undecenoic acid in a mass ratio of 2:4.

[0040] Comparative Preparation Example 1 The preparation method of the modified toughened particles is different from that of Preparation Example 1 in that the raw materials are different.

[0041] An equal amount of γ-methacryloxypropyltrimethoxysilane is used to replace the amino silane coupling agent and the long-chain olefinic acid, that is, the raw material contains 170 g of γ-methacryloxypropyltrimethoxysilane, and does not contain the amino silane coupling agent and the long-chain olefinic acid.

[0042] The specific preparation steps are: The inorganic nanoparticles are stirred and dispersed in the first solvent, γ-methacryloxypropyltrimethoxysilane is added, and the mixture is heated to 50° C. for reaction for 1.5 hours. After the reaction is completed, the mixture is filtered, washed with an ethanol solution, and dried at 60° C. to obtain pretreated inorganic nanoparticles. The pretreated nano inorganic rigid particles are stirred and dispersed in a third solvent, nitrogen is introduced for protection, styrene monomer and isoprene monomer are added, and after mixing evenly, an initiator solution is added, the initiator solution consists of 0.2L of anhydrous ethanol containing 10wt% of initiator, and the mixture is heated to 70°C for reaction for 3.5h. After the reaction is completed, the mixture is filtered, washed with ethanol solution, and dried at 60°C to obtain modified toughened particles.

[0043] Comparative Preparation Example 2 The preparation method of the modified toughened particles is different from that of Preparation Example 1 in that the raw materials are different.

[0044] The styrene monomer was replaced with an equal amount of isoprene monomer, that is, the raw material contained 250 g of isoprene monomer and did not contain styrene monomer.

[0045] Specific steps for preparing modified toughened particles: The grafted nano inorganic rigid particles are stirred and dispersed in the third solvent, nitrogen is introduced for protection, isoprene monomer is added, and after mixing evenly, an initiator solution is added, the initiator solution consists of 0.2L of anhydrous ethanol containing 10wt% of initiator, and the mixture is heated to 70°C for reaction for 3.5h. After the reaction is completed, the mixture is filtered, washed with ethanol solution, and dried at 60°C to obtain modified toughened particles.

[0046] Comparative Preparation Example 3 The preparation method of the modified toughened particles is different from that of Preparation Example 1 in that the raw materials are different.

[0047] An equal amount of styrene monomer was used to replace the isoprene monomer, that is, the raw material contained 250 g of styrene monomer and no isoprene monomer.

[0048] Specific steps for preparing modified toughened particles: The grafted nano inorganic rigid particles are stirred and dispersed in a third solvent, nitrogen is introduced for protection, styrene monomer is added, and after mixing evenly, an initiator solution is added, the initiator solution consists of 0.2L of anhydrous ethanol containing 10wt% of initiator, and the mixture is heated to 70°C for reaction for 3.5h. After the reaction is completed, the particles are filtered, washed with ethanol solution, and dried at 60°C to obtain modified toughened particles.

[0049] Example 1

[0050] A method for preparing a PP-R water supply pipe resistant to low temperature cracking comprises the following steps: 10 kg of PP-R resin, 0.4 kg of elastomer, 0.35 kg of modified toughening particles and 0.05 kg of masterbatch were premixed at 70° C. for 30 minutes to obtain a premix.

[0051] Specifically, the PP-R resin comes from Hyosung R200P; the elastomer comes from EMAAC1820, and the acrylic acid value content is 20%; the modified toughening particles are prepared by Preparation Example 1; and the masterbatch comes from gray J9114.

[0052] The premix is ​​put into a single-screw extruder, and is plasticized into a viscous flow state through heating, mixing and shearing. Under the high pressure of the extruder, a pipe blank is formed through the diversion and compression action of the die head. The barrel temperature of the extruder is 180°C in zone one, 185°C in zone two, 185°C in zone three, 185°C in zone four and 190°C in zone five. Under the traction action of the traction machine, the premix is ​​shaped through the cooling and shaping action of the vacuum shaping box to obtain a water supply pipe.

[0053] Example 2

[0054] A method for preparing a PP-R water supply pipe resistant to low temperature cracking, which differs from Example 1 in that the raw materials are different.

[0055] 10 kg of PP-R resin, 0.7 kg of elastomer, 0.6 kg of modified toughening particles and 0.2 kg of masterbatch were premixed at 70° C. for 30 minutes to obtain a premix.

[0056] Specifically, the PP-R resin comes from Hyosung R200P; the elastomer comes from Dow EMAAC1820, and the acrylic acid value content is 20%; the modified toughening particles are prepared by Preparation Example 2; and the masterbatch comes from gray J9114.

[0057] Example 3

[0058] A method for preparing a PP-R water supply pipe resistant to low temperature cracking, which differs from Example 1 in that the raw materials are different.

[0059] 10 kg of PP-R resin, 0.5 kg of elastomer, 0.5 kg of modified toughening particles and 0.1 kg of masterbatch were premixed at 70° C. for 30 minutes to obtain a premix.

[0060] Specifically, the PP-R resin comes from Hyosung R200P; the elastomer comes from EMAAC1820, and the acrylic acid value content is 20%; the modified toughening particles are prepared by Preparation Example 1; and the masterbatch comes from gray J9114.

[0061] Example 4

[0062] A method for preparing a PP-R water supply pipe resistant to low temperature cracking, which differs from Example 3 in that the raw materials are different.

[0063] The modified toughened particles are prepared by Preparation Example 3.

[0064] Example 5

[0065] A method for preparing a PP-R water supply pipe resistant to low temperature cracking, which differs from Example 3 in that the raw materials are different.

[0066] The modified toughened particles are prepared by Preparation Example 4.

[0067] Example 6

[0068] A method for preparing a PP-R water supply pipe resistant to low temperature cracking, which differs from Example 3 in that the raw materials are different.

[0069] The modified toughened particles are prepared by Preparation Example 5.

[0070] Example 7

[0071] A method for preparing a PP-R water supply pipe resistant to low temperature cracking, which differs from Example 3 in that the raw materials are different.

[0072] The elastomer is from Dow EMA4051, with methyl acrylate content of 25%.

[0073] Example 8

[0074] A method for preparing a PP-R water supply pipe resistant to low temperature cracking, which differs from Example 3 in that the raw materials are different.

[0075] The elastomer is from Dow EMAAC34035, with a methyl acrylate content of 28%.

[0076] Comparative Example 1 A method for preparing a PP-R water supply pipe, which differs from Example 3 in that the raw materials are different.

[0077] In the premix, the modified toughening particles are replaced by an equal amount of elastomer, that is, the raw material contains 1 kg of elastomer and no modified toughening particles.

[0078] Comparative Example 2 A method for preparing a PP-R water supply pipe, which differs from Example 3 in that the raw materials are different.

[0079] In the premix, the modified toughened particles are prepared by Comparative Preparation Example 1.

[0080] Comparative Example 3 A method for preparing a PP-R water supply pipe, which differs from Example 3 in that the raw materials are different.

[0081] In the premix, the modified toughened particles are prepared by Comparative Preparation Example 2.

[0082] Comparative Example 4 A method for preparing a PP-R water supply pipe, which differs from Example 3 in that the raw materials are different.

[0083] In the premix, the modified toughened particles are prepared by Comparative Preparation Example 3.

[0084] Performance Testing Simply supported beam impact test: refer to the simply supported beam impact test requirements in GB / T18742.2-2017. Before the test, the water pipe was placed in a refrigerator at 0±2℃ for 2h and then taken out for testing. A total of 10 water pipes were tested and the breakage rate was recorded. The results are shown in Table 1.

[0085] Low-temperature drop hammer test: A drop hammer weighing 1 kg is used to hit the water supply pipe in a free-fall manner. The release height of the drop hammer is 110 cm. Before the test, the water supply pipe is placed in a -20±2℃ refrigerator for 2 hours and then taken out. After the surface of the water supply pipe returns to 0℃, the above test is carried out. A total of 10 water supply pipes are tested and the breakage rate is recorded. The results are shown in Table 1.

[0086] Hydrostatic test: Referring to the hydrostatic test strength requirements in GB / T18742.2-2017, the water supply pipe was tested for high temperature creep performance at 95°C. The results are shown in Table 2.

[0087] Table 1

[0088] Table 2

[0089] According to the above test results, the PP-R pipes prepared in Examples 1-3 were not damaged after being subjected to the impact of a simply supported beam, which proves that the low-temperature anti-cracking performance is good, and there was no leakage or cracking after being subjected to the hydrostatic test, which proves that the high-temperature creep performance is good, and thus it is suitable for application scenarios with high comprehensive performance requirements.

[0090] Combining the test results of Example 3 and Comparative Example 1, it can be analyzed that when the amount of elastomer added is small, the modified toughening particles can effectively compensate for the deficiencies of the elastomer, enhance the low-temperature toughness of the PP-R pipe, and improve the effect of simple elastomer toughening on high-temperature creep performance.

[0091] Combining the test results of Example 3 with those of Comparative Example 2, it can be analyzed that when the copolymer is polymerized on the surface of nano inorganic rigid particles through long-chain olefinic acid, the surface compatibility of the modified toughening particles can be promoted, the dispersibility of the modified toughening particles and the binding force with the elastomer and the PP-R resin can be improved, and compared with the short-chain γ-methacryloxypropyltrimethoxysilane as the grafting site, the low-temperature crack resistance and high-temperature creep performance of the PP-R pipe can be effectively improved.

[0092] Combining the test results of Example 3 with Comparative Examples 3 and 4, it can be analyzed that when isoprene monomer and styrene monomer are polymerized to form a copolymer, the toughening effect of the modified toughening particles can be effectively exerted, while improving the low-temperature crack resistance and high-temperature creep performance of the PP-R pipe.

[0093] Combining the test results of Example 3 with Example 4, Example 5 and Example 6, it can be analyzed that when the long-chain olefinic acid is compounded with 8-nonenoic acid and 10-undecenoic acid according to (1-2): (3-4), the modified toughening particles can be further compatible with the PP-R resin system, further improving the low-temperature toughness of the PP-R pipe.

[0094] Combining the test results of Example 3 with those of Example 7 and Example 8, it can be analyzed that when the mass content of methyl acrylate in the elastomer ethylene-methyl acrylate copolymer is 25-28%, the low-temperature toughness of the PP-R pipe can be further improved.

[0095] This specific implementation manner is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the specific implementation manner as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A PP-R water supply pipe resistant to low temperature cracking, characterized in that: The invention comprises the following raw materials in parts by weight: PP-R resin 100 parts; 4~7 parts of elastomer; 3.5~6 parts of modified toughening particles; The modified toughened particles are formed by grafting long-chain olefinic acid onto nano-inorganic rigid particles and then polymerizing styrene monomer and isoprene monomer. The mass ratio of the nano-inorganic rigid particles, long-chain olefinic acid, styrene monomer and isoprene monomer is (10-20):(1-3):(1-2.5):(1.5-3).

2. The PP-R water supply pipe resistant to low temperature cracking according to claim 1, characterized in that: The nano inorganic rigid particles are first modified by an amino-containing silane coupling agent and then grafted with a long-chain olefinic acid. The mass ratio of the nano inorganic rigid particles to the amino-containing silane coupling agent is (10-20):(0.7-2.2).

3. The PP-R water supply pipe resistant to low temperature cracking according to claim 1, characterized in that: The method for preparing the modified toughened particles comprises the following steps: The nano inorganic rigid particles are dispersed in a first solvent, an amino-containing silane coupling agent is added and reacted, and after the reaction is completed, the particles are filtered, washed, and dried to obtain pretreated nano inorganic rigid particles; Pre-treated nano inorganic rigid particles are dispersed in a second solvent, long chain olefinic acid is added and reacted, and after the reaction is completed, the particles are filtered, washed and dried to obtain grafted nano inorganic rigid particles; The grafted inorganic nano rigid particles are dispersed in a third solvent, styrene monomer and isoprene monomer are added, and after being mixed evenly, an initiator is added to react. After the reaction is completed, the particles are filtered, washed and dried to obtain modified toughened particles.

4. The PP-R water supply pipe resistant to low temperature cracking according to claim 1, characterized in that: The long-chain olefinic acid includes one or more of 8-nonenoic acid, 10-undecenoic acid and 12-tridecenoic acid.

5. The PP-R water supply pipe resistant to low temperature cracking according to claim 1, characterized in that: The long-chain olefinic acid is a compound of 8-nonenoic acid and 10-undecenoic acid, and the mass ratio of the 8-nonenoic acid to the 10-undecenoic acid is (1-2):(3-4).

6. The PP-R water supply pipe resistant to low temperature cracking according to claim 1, characterized in that: The elastomer includes one or more of ethylene-methyl acrylate copolymer, nitrile rubber, EPDM rubber and ethylene-octene copolymer.

7. The PP-R water supply pipe resistant to low temperature cracking according to claim 1, characterized in that: The elastomer is ethylene-methyl acrylate copolymer, and the mass content of methyl acrylate in the ethylene-methyl acrylate copolymer is 25-28%.

8. The PP-R water supply pipe resistant to low temperature cracking according to claim 1, characterized in that: The nano inorganic rigid particles include one or more of nano calcium carbonate, silicon dioxide, titanium dioxide and carbon fiber.

9. A PP-R water supply pipe resistant to low temperature cracking according to any one of claims 1 to 8, characterized in that: The raw materials also include 0.5 to 3 parts by weight of masterbatch.

10. A method for preparing a PP-R water supply pipe resistant to low temperature cracking according to any one of claims 1 to 9, characterized in that: The following steps are involved: Premixing PP-R resin, elastomer and modified toughening particles to obtain a premix; The premix is ​​heated, mixed and sheared to be plasticized into a viscous flow state, extruded to form a tube blank, and drawn, cooled and shaped into a water supply pipe.

Images