A PP-R water supply pipe resistant to low-temperature cracking and its preparation method

Abstract

The present application discloses a low-temperature crack-resistant PP-R water supply pipe and a preparation method thereof, belonging to the field of pipe materials. A low-temperature crack-resistant PP-R water supply pipe is prepared from the following raw materials in parts by weight: 100 parts of PP-R resin; 4 to 7 parts of elastomer; 3.5 to 6 parts of modified toughening particles. The modified toughening particles are obtained by grafting long-chain acrylic acid with nano-inorganic rigid particles and then polymerizing styrene monomer and isoprene monomer. The mass ratio of the nano-inorganic rigid particles, long-chain acrylic acid, styrene monomer and isoprene monomer is (10 to 20):(1 to 3):(1 to 2.5):(1.5 to 3). The present application has the effect of improving the low-temperature toughness of the PP-R pipe while maintaining the high-temperature creep performance at a good level.

Description

Technical Field

[0001] This application relates to the field of pipe materials, and in particular, to a low-temperature cracking resistant PP-R water supply pipe 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 supply pipe in building water supply and drainage systems. Coupled with its long service life, it has gradually become the standard configuration for newly built residential buildings and public facilities in many countries and regions. However, with the increasingly widespread application of PP-R pipes, it is found that PP-R pipes are prone to low-temperature brittle fracture. Especially when PP-R pipes are used in cold regions or outdoors in winter, it 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, currently, the method of toughening with elastomers is adopted. The addition amount of the elastomer is generally 15wt% - 30wt%. The elastomer such as ethylene-octene copolymer can effectively absorb part of the impact energy and relieve the crack propagation trend to improve toughness.

[0004] However, the addition of elastomers will significantly reduce the high-temperature creep performance of PP-R pipes, resulting in limited application of PP-R pipes and difficulty in applying them to scenarios with high comprehensive performance requirements. Summary of the Invention

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

[0006] In the first aspect, a low-temperature cracking resistant PP-R water supply pipe provided by this application adopts the following technical solution:

[0007] A low-temperature cracking resistant PP-R water supply pipe is prepared from raw materials including the following parts by weight:

[0008] PP-R resin: 100 parts;

[0009] Elastomer: 4 - 7 parts;

[0010] Modified toughening particles: 3.5 - 6 parts;

[0011] The modified toughening particles are obtained by grafting long-chain unsaturated acids onto nano-inorganic rigid particles and then polymerizing styrene monomers and isoprene monomers. The mass ratio of the nano-inorganic rigid particles, long-chain unsaturated acids, styrene monomers, and isoprene monomers is (10 - 20):(1 - 3):(1 - 2.5):(1.5 - 3).

[0012] By adopting the above technical solution, an elastomer is added on the basis of the PP-R resin. The elastomer can play a role in consuming impact energy and controlling the development of cracks. In addition, modified toughening particles are also added. The addition of the modified toughening particles can reduce the dosage of the elastomer and reduce the influence on the high-temperature creep performance of the pipe.

[0013] The modified toughening particles are modified on the basis of nano-inorganic rigid particles. The distribution of the 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. The nano-inorganic rigid particles are easily affected by problems such as agglomeration and dispersion. Therefore, long-chain acrylic acid, styrene and isoprene copolymer are polymerized on the surface of the nano-inorganic rigid particles to reduce the surface energy of the nano-inorganic rigid particles, promote the dispersion of the modified toughening particles. At the same time, the polyolefin structure of the copolymer has better compatibility with the PP-R resin system, the interfacial bonding force is improved, and the high-temperature creep performance is stronger. Selecting long-chain acrylic acid introduces a certain degree of voids between the copolymer and the nano-inorganic rigid particles, which can not only provide a combination for the elastomer and the PP-R resin, but also when the pipe is impacted, the structure of the modified toughening particles slides relatively, so that sufficient toughness can be maintained even in a low-temperature environment and it is not easy to crack.

[0014] Optionally, the nano-inorganic rigid particles are first modified with an amino-silane coupling agent and then grafted with long-chain acrylic acid. The mass ratio of the nano-inorganic rigid particles to the amino-silane coupling agent is (10~20):(0.7~2.2).

[0015] By adopting the above technical solution, after being modified with an amino-silane coupling agent, amino functional groups are introduced into the nano-inorganic rigid particles, which not only makes it easier for long-chain acrylic acid to graft, but also forms a spatial structure that is easy to slide relatively, improving the low-temperature toughness of the PP-R pipe.

[0016] Optionally, the long-chain acrylic acid includes one or more of 8-nonenoic acid, 10-undecenoic acid and 12-tridecenoic acid.

[0017] By adopting the above technical solution, the above long-chain acrylic acid can provide polymerization sites to realize the polymerization of styrene-isoprene copolymer on the surface of the nano-inorganic rigid particles.

[0018] Optionally, the long-chain acrylic acid is selected as 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).

[0019] By adopting the above technical solution, acrylic acid with a suitable chain segment length is selected, and the surface spatial structure is modified in a compound and staggered manner, which is better compatible with the PP-R resin system, thereby further improving the low-temperature toughness.

[0020] Optionally, the elastomer includes one or more of ethylene-methyl acrylate copolymer, nitrile butadiene rubber, ethylene propylene diene monomer rubber, and ethylene-octene copolymer.

[0021] By adopting the above technical solution, the above elastomer can play a role in consuming impact energy and controlling crack development in the PP-R resin.

[0022] Optionally, the elastomer is selected as ethylene-methyl acrylate copolymer, and the mass content of methyl acrylate in the ethylene-methyl acrylate copolymer is 25-28%.

[0023] By adopting the above technical solution, the ethylene-methyl acrylate copolymer has good flexible anti-cracking ability, 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.

[0024] Optionally, the nano-inorganic rigid particles include one or more of nano-scale calcium carbonate, silicon dioxide, titanium dioxide, and carbon fiber.

[0025] Optionally, the raw materials further include 0.5-3 parts by weight of masterbatch.

[0026] By adopting the above technical solution, the PP-R pipe can present various design colorings.

[0027] In a second aspect, a preparation method of a low-temperature crack-resistant PP-R water supply pipe provided by the present application adopts the following technical solution:

[0028] A preparation method of a low-temperature crack-resistant PP-R water supply pipe includes the following steps:

[0029] Pre-mix the PP-R resin, elastomer, and modified toughening particles to obtain a pre-mixture;

[0030] The pre-mixture is heated, kneaded, and sheared to be plasticized into a viscous flow state, extruded to form a pipe blank, and drawn and cooled and shaped into a water supply pipe.

[0031] Optionally, the preparation method of the modified toughening particles includes the following steps:

[0032] Disperse the nano-inorganic rigid particles in a first solvent, add an amino-silane coupling agent and react, filter, wash, and dry after the reaction to obtain pretreated nano-inorganic rigid particles;

[0033] Disperse the pretreated nano-inorganic rigid particles in a second solvent, add a long-chain olefinic acid and react, filter, wash, and dry after the reaction to obtain grafted nano-inorganic rigid particles;

[0034] Grafting nano-inorganic rigid particles are dispersed in a third solvent, styrene monomer and isoprene monomer are added, and after mixing evenly, an initiator is added for reaction. After the reaction is completed, filtration, washing, and drying are carried out to obtain modified toughening particles.

[0035] By adopting the above technical solution, the surface grafting and polymerization of nano-inorganic rigid particles are realized in three steps, thereby improving the uniformity and stability of the surface of the modified toughening particles.

[0036] In summary, the present application has the following beneficial effects:

[0037] 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 stress concentration state. When the pipe is impacted, internal cracks will be hindered by the nano-inorganic rigid particles, making the pipe not easily cracked. Nano-inorganic rigid particles are easily affected by dispersion problems such as agglomeration. Therefore, long-chain acrylic acid, styrene, and isoprene copolymer are polymerized on the surface of the nano-inorganic rigid particles to reduce the surface energy of the nano-inorganic rigid particles, promote the dispersion of the modified toughening particles, and at the same time, the polyolefin structure of the copolymer has better compatibility with the PP-R resin system, the interfacial bonding force is improved, and the high-temperature creep performance is stronger. Selecting long-chain acrylic acid introduces a certain degree of voids between the copolymer and the nano-inorganic rigid particles, which can not only provide a place for the elastomer and PP-R resin to combine, but also when the pipe is impacted, the structure of the modified toughening particles slides relatively, so that sufficient toughness can be maintained even in a low-temperature environment and it is not easily cracked.

[0038] 2. The present application can select acrylic acid with an appropriate chain segment length and compound and modify the staggered surface space structure, which is better compatible with the PP-R resin system, thereby further improving the low-temperature toughness. Specific Embodiments

[0039] The following further details the present application.

[0040] Preparation Example 1

[0041] A preparation method of modified toughening particles, comprising the following steps:

[0042] Weigh 1000 g of nano-inorganic rigid particles, 70 g of amino-silane coupling agent, 100 g of long-chain acrylic acid, 40 g of triethylamine, 100 g of styrene monomer, 150 g of isoprene monomer, and 5 g of initiator. Additionally, measure 5 L each of the first solvent, the second solvent, and the third solvent. The first solvent and the second solvent are 92 wt% ethanol solutions, and the third solvent is anhydrous ethanol.

[0043] Specifically, the nano-inorganic rigid particles are nano-calcium carbonate; the amino-silane coupling agent is γ-aminopropyltriethoxysilane; the long-chain acrylic acid is 10-undecenoic acid; the initiator is azobisisobutyronitrile.

[0044] The nano-inorganic rigid particles are stirred and dispersed in the first solvent, and an amino-silane coupling agent is added. It is heated to 50 °C and reacted for 1.5 h. After the reaction, it is filtered, washed with an ethanol solution, and dried at 60 °C to obtain the pretreated nano-inorganic rigid particles;

[0045] The pretreated nano-inorganic rigid particles are stirred and dispersed in the second solvent. After adding triethylamine and dispersing evenly, long-chain unsaturated acid is added. It is heated to 65 °C and reacted for 2 h. After the reaction, it is filtered, washed with an ethanol solution, and dried at 60 °C to obtain the grafted nano-inorganic rigid particles;

[0046] The grafted nano-inorganic rigid particles are stirred and dispersed in the third solvent, and nitrogen is introduced for protection. Styrene monomer and isoprene monomer are added. After mixing evenly, an initiator solution is added. The initiator solution consists of 0.2 L of absolute ethanol containing 10 wt% initiator. It is heated to 70 °C and reacted for 3.5 h. After the reaction, it is filtered, washed with an ethanol solution, and dried at 60 °C to obtain the modified toughening particles.

[0047] Preparation Example 2

[0048] The preparation method of the modified toughening particles is different from that of Preparation Example 1 in terms of raw materials.

[0049] Weigh 2000 g of nano-inorganic rigid particles, 220 g of amino-silane coupling agent, 300 g of long-chain unsaturated acid, 60 g of triethylamine, 250 g of styrene monomer, 300 g of isoprene monomer, and 8 g of initiator.

[0050] Specifically, the nano-inorganic rigid particles are nano-calcium carbonate; the amino-silane coupling agent is γ-aminopropyltriethoxysilane; the long-chain unsaturated acid is 10-undecenoic acid; the initiator is azobisisobutyronitrile.

[0051] Preparation Example 3

[0052] The preparation method of the modified toughening particles is different from that of Preparation Example 1 in terms of raw materials.

[0053] Specifically, the long-chain unsaturated acid is 8-nonenoic acid.

[0054] Preparation Example 4

[0055] The preparation method of the modified toughening particles is different from that of Preparation Example 1 in terms of raw materials.

[0056] Specifically, the long-chain unsaturated acid is a compound of 8-nonenoic acid and 10-undecenoic acid in a mass ratio of 1:3.

[0057] Preparation Example 5

[0058] The preparation method of the modified toughening particles is different from that of Preparation Example 1 in terms of raw materials.

[0059] Specifically, the long-chain unsaturated fatty acid is a compound of 8-nonenoic acid and 10-undecenoic acid in a mass ratio of 2:4.

[0060] Comparative Preparation Example 1

[0061] The preparation method of the modified toughening particles is different from that of Preparation Example 1 in terms of raw materials.

[0062] Replace the amino-silane coupling agent and the long-chain unsaturated fatty acid with an equal amount of γ-methacryloxypropyltrimethoxysilane, that is, the raw materials include 170 g of γ-methacryloxypropyltrimethoxysilane, and do not include the amino-silane coupling agent and the long-chain unsaturated fatty acid.

[0063] The specific preparation steps are as follows:

[0064] The nano-inorganic rigid particles are stirred and dispersed in the first solvent, γ-methacryloxypropyltrimethoxysilane is added, and the mixture is heated to 50 °C and reacted for 1.5 h. After the reaction is completed, filtration is carried out, and the product is washed with an ethanol solution and dried at 60 °C to obtain the pretreated nano-inorganic rigid particles;

[0065] The pretreated nano-inorganic rigid particles are stirred and dispersed in the third solvent, nitrogen is introduced for protection, styrene monomer and isoprene monomer are added. After mixing evenly, an initiator solution is added. The initiator solution consists of 0.2 L of absolute ethanol containing 10 wt% initiator. The mixture is heated to 70 °C and reacted for 3.5 h. After the reaction is completed, filtration is carried out, and the product is washed with an ethanol solution and dried at 60 °C to obtain the modified toughening particles.

[0066] Comparative Preparation Example 2

[0067] The preparation method of the modified toughening particles is different from that of Preparation Example 1 in terms of raw materials.

[0068] Replace the styrene monomer with an equal amount of isoprene monomer, that is, the raw materials include 250 g of isoprene monomer and do not include the styrene monomer.

[0069] The specific steps for preparing the modified toughening particles are as follows:

[0070] The grafted nano-inorganic rigid particles are stirred and dispersed in the third solvent, nitrogen is introduced for protection, isoprene monomer is added. After mixing evenly, an initiator solution is added. The initiator solution consists of 0.2 L of absolute ethanol containing 10 wt% initiator. The mixture is heated to 70 °C and reacted for 3.5 h. After the reaction is completed, filtration is carried out, and the product is washed with an ethanol solution and dried at 60 °C to obtain the modified toughening particles.

[0071] Comparative Preparation Example 3

[0072] The preparation method of the modified toughening particles is different from that of Preparation Example 1 in terms of raw materials.

[0073] Replace the isoprene monomer with an equal amount of styrene monomer, that is, the raw material contains 250 g of styrene monomer and does not contain isoprene monomer.

[0074] Specific steps for preparing the modified toughening particles:

[0075] The grafted nano-inorganic rigid particles are stirred and dispersed in the third solvent, protected by introducing nitrogen, styrene monomer is added, and after mixing evenly, an initiator solution is added. The initiator solution consists of 0.2 L of absolute ethanol containing 10 wt% initiator. It is heated to 70 °C and reacted for 3.5 h. After the reaction, it is filtered, washed with ethanol solution, and dried at 60 °C to obtain the modified toughening particles.

[0076] Example 1

[0077] A preparation method of a low-temperature crack-resistant PP-R water supply pipe includes the following steps:

[0078] 10 kg of PP-R resin, 0.4 kg of elastomer, 0.35 kg of modified toughening particles, and 0.05 kg of masterbatch are premixed at 70 °C for 30 min to obtain a premix.

[0079] Specifically, the PP-R resin is from Hyosung R200P; the elastomer is from EMAAC1820, with an acrylic acid value content of 20%; the modified toughening particles are prepared from Preparation Example 1; the masterbatch is from gray J9114.

[0080] The premix is put into a single-screw extruder, heated, kneaded, and sheared to be plasticized into a viscous flow state. Under the high pressure of the extruder, it forms a pipe blank through the flow splitting and compression of the die head. The barrel temperature of the extruder is 180 °C in zone 1, 185 °C in zone 2, 185 °C in zone 3, 185 °C in zone 4, and 190 °C in zone 5. Under the traction of the tractor, it is shaped by the cooling and shaping of the vacuum sizing box to obtain the water supply pipe.

[0081] Example 2

[0082] A preparation method of a low-temperature crack-resistant PP-R water supply pipe is different from that of Example 1 in terms of raw materials.

[0083] 10 kg of PP-R resin, 0.7 kg of elastomer, 0.6 kg of modified toughening particles, and 0.2 kg of masterbatch are premixed at 70 °C for 30 min to obtain a premix.

[0084] Specifically, the PP-R resin is from Hyosung R200P; the elastomer is from Dow EMAAC1820, with an acrylic acid value content of 20%; the modified toughening particles are prepared from Preparation Example 2; the masterbatch is from gray J9114.

[0085] Example 3

[0086] A preparation method of a low-temperature crack-resistant PP-R water supply pipe, which is different from that of Example 1 in terms of raw materials.

[0087] 10 kg of PP-R resin, 0.5 kg of elastomer, 0.5 kg of modified toughening particles and 0.1 kg of masterbatch are premixed at 70 °C for 30 min to obtain a premix.

[0088] Specifically, the PP-R resin is from Hyosung R200P; the elastomer is from EMAAC1820 with an acrylic acid value content of 20%; the modified toughening particles are prepared from Preparation Example 1; the masterbatch is from gray J9114.

[0089] Example 4

[0090] A preparation method of a low-temperature crack-resistant PP-R water supply pipe, which is different from that of Example 3 in terms of raw materials.

[0091] The modified toughening particles are prepared from Preparation Example 3.

[0092] Example 5

[0093] A preparation method of a low-temperature crack-resistant PP-R water supply pipe, which is different from that of Example 3 in terms of raw materials.

[0094] The modified toughening particles are prepared from Preparation Example 4.

[0095] Example 6

[0096] A preparation method of a low-temperature crack-resistant PP-R water supply pipe, which is different from that of Example 3 in terms of raw materials.

[0097] The modified toughening particles are prepared from Preparation Example 5.

[0098] Example 7

[0099] A preparation method of a low-temperature crack-resistant PP-R water supply pipe, which is different from that of Example 3 in terms of raw materials.

[0100] The elastomer is from Dow EMA4051 with a methyl acrylate content of 25%.

[0101] Example 8

[0102] A preparation method of a low-temperature crack-resistant PP-R water supply pipe, which is different from that of Example 3 in terms of raw materials.

[0103] The elastomer is from Dow EMAAC34035 with a methyl acrylate content of 28%.

[0104] Comparative Example 1

[0105] A preparation method of a PP-R water supply pipe, which is different from that of Example 3 in terms of raw materials.

[0106] In the premix, the modified toughening particles are replaced with an equal amount of elastomer, that is, the raw materials contain 1 kg of elastomer and do not contain modified toughening particles.

[0107] Comparative Example 2

[0108] A method for preparing a PP-R water supply pipe, which is different from Example 3 in terms of raw materials.

[0109] In the premix, the modified toughening particles are prepared from Comparative Preparation Example 1.

[0110] Comparative Example 3

[0111] A method for preparing a PP-R water supply pipe, which is different from Example 3 in terms of raw materials.

[0112] In the premix, the modified toughening particles are prepared from Comparative Preparation Example 2.

[0113] Comparative Example 4

[0114] A method for preparing a PP-R water supply pipe, which is different from Example 3 in terms of raw materials.

[0115] In the premix, the modified toughening particles are prepared from Comparative Preparation Example 3.

[0116] Performance Test

[0117] Simply supported beam impact test: Referring to the requirements of the simply supported beam impact test in GB / T18742.2-2017, before the test, the water supply pipe is first placed in a refrigerated box at 0±2°C for 2 h, and then taken out for testing. A total of 10 water supply pipes are tested, and the breakage rate is recorded. The results are shown in Table 1.

[0118] Low-temperature drop hammer test: A drop hammer with a weight of 1 kg hits the water supply pipe in a free-fall manner, and the release height of the drop hammer is 110 cm. Before the test, the water supply pipe is first placed in a refrigerated box at -20±2°C for 2 h, and then taken out. After the surface of the water supply pipe returns to 0°C, 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.

[0119] Hydrostatic test: Referring to the hydrostatic test strength requirements in GB / T18742.2-2017, for the high-temperature creep performance, the hydrostatic test of the water supply pipe at 95°C is carried out, and the results are shown in Table 2.

[0120] Table 1

[0121]

[0122] Table 2

[0123]

[0124] According to the above test results, the PP-R pipes prepared in Examples 1-3 showed no damage after being subjected to the simply supported beam impact, proving good low-temperature anti-cracking performance. And after being subjected to the hydrostatic test, there was no leakage or rupture, proving good high-temperature creep performance. Therefore, it is applicable to application scenarios with high comprehensive performance requirements.

[0125] Combining the test results of Example 3 and Comparative Example 1, it can be analyzed that when the addition amount of the elastomer is small, the modified toughening particles can effectively compensate for the deficiency of the elastomer, enhance the low-temperature toughness of the PP-R pipe, and improve the influence on the high-temperature creep performance when only the elastomer is used for toughening.

[0126] Combining the test results of Example 3 and Comparative Example 2, it can be analyzed that when the copolymer is polymerized on the surface of the nano-inorganic rigid particles through long-chain acrylic acid, it can promote the surface compatibility of the modified toughening particles, improve the dispersibility of the modified toughening particles and the binding force with the elastomer and the PP-R resin. Compared with the short-chain γ-methacryloxypropyltrimethoxysilane as the grafting site, it can effectively improve the low-temperature anti-cracking performance and high-temperature creep performance of the PP-R pipe.

[0127] Combining the test results of Example 3, Comparative Example 3 and Comparative Example 4, it can be analyzed that when copolymerized from isoprene monomer and styrene monomer, it can effectively play the toughening role of the modified toughening particles, and at the same time improve the low-temperature anti-cracking performance and high-temperature creep performance of the PP-R pipe.

[0128] Combining the test results of Example 3, Example 4, Example 5 and Example 6, it can be analyzed that when 8-nonenoic acid and 10-undecenoic acid are compounded in a ratio of (1~2):(3~4) as the long-chain acrylic acid, it can make the modified toughening particles further compatible with the PP-R resin system and further improve the low-temperature toughness of the PP-R pipe.

[0129] Combining the test results of Example 3, Example 7 and Example 8, it can be analyzed that when the mass content of methyl acrylate in the ethylene-methyl acrylate copolymer elastomer is 25~28%, it can further improve the low-temperature toughness of the PP-R pipe.

[0130] This specific embodiment is only an interpretation of the present application, and it is not a limitation of the present application. Those skilled in the art can make modifications without creative contributions to this specific embodiment according to needs after reading this specification, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

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: 100 parts of PP-R resin; 4-7 parts of elastomer; 3.5-6 parts of modified toughening particles; the modified toughening particles are prepared by grafting long-chain olefinic acid onto nano inorganic rigid particles, and then polymerizing styrene monomer and isoprene monomer, wherein 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); The long-chain olefinic acid includes one or more of 8-nonenoic acid, 10-undecenoic acid and 12-tridecenoic acid.

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. A PP-R water supply pipe resistant to low temperature cracking according to claim 2, characterized in that: The preparation method of the modified toughened particles comprises the following steps: dispersing nano inorganic rigid particles in a first solvent, adding an amino silane coupling agent and reacting, filtering after the reaction, washing and drying to obtain pretreated nano inorganic rigid particles; dispersing the pretreated nano inorganic rigid particles in a second solvent, adding a long chain olefinic acid and reacting, filtering after the reaction, washing and drying to obtain grafted nano inorganic rigid particles; dispersing the grafted nano inorganic rigid particles in a third solvent, adding styrene monomer and isoprene monomer, mixing evenly and then adding an initiator to react, filtering after the reaction, washing and drying 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 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).

5. 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.

6. 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%.

7. 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.

8. A PP-R water supply pipe resistant to low temperature cracking according to any one of claims 1 to 7, characterized in that: The raw materials also include 0.5 to 3 parts by weight of masterbatch.

9. A method for preparing a PP-R water supply pipe resistant to low temperature cracking according to any one of claims 1 to 7, characterized in that: The following steps are involved: PP-R resin, elastomer and modified toughening particles are premixed to obtain a premix; the premix is ​​heated, mixed and sheared, plasticized into a viscous flow state, extruded to form a tube blank, and drawn, cooled and shaped into a water supply pipe.

Images