Reinforced ppr pipe and method for producing the same

Abstract

This invention discloses a reinforced PPR pipe and its preparation method, belonging to the field of polymer pipe processing technology. The raw materials for this pipe include PPR resin, coloring masterbatch, a topological network nucleating agent, hyperbranched polymer-grafted nano-silica, and an elastomer. The topological network nucleating agent is a carboxyl-terminated polyethylene glycol-grafted β-nucleating agent@polydopamine / graphene oxide quantum dot composite; the hyperbranched polymer-grafted nano-silica is hyperbranched polyethyleneimine covalently grafted nano-silica. This invention also discloses the preparation method of the pipe, including melt extrusion, annealing, and gradient slow cooling. This invention significantly improves the β-crystal content of the PPR pipe through the synergistic nucleation of the topological network nucleating agent and the hyperbranched polymer-grafted nano-silica, giving it both high ring stress strength and excellent impact toughness, resulting in superior overall performance.

Description

Technical Field

[0001] This invention relates to the field of polymer pipe processing technology, specifically a reinforced PPR pipe and its preparation method. Background Technology

[0002] PPR pipes are widely used in building water supply, heating systems, and industrial fluid transportation due to their excellent corrosion resistance and non-toxic and environmentally friendly properties. However, the brittle behavior of this material at low temperatures and the strength degradation during long-term use have always been industry pain points that restrict its high-end applications. Introducing β-nucleating agents to induce the formation of β-crystals in polypropylene has been proven to be an effective technical approach to significantly improve the toughness, impact resistance, and long-term durability of PPR pipes.

[0003] Nevertheless, current technologies based on β-nucleating agent modification still face several key bottlenecks: Limited nucleation efficiency: The single β nucleating agent is unevenly dispersed in the PPR matrix, and the induced β crystal content is usually low; Toughness enhancement is limited: relying solely on nucleating agents can only improve the material's impact resistance to a limited extent, making it difficult to achieve both high strength and high toughness.

[0004] Therefore, it is of great significance for the industry to develop a PPR pipe and an efficient preparation method that can achieve high β crystal content while ensuring that the pipe has excellent and balanced mechanical properties (such as high strength and high toughness). Summary of the Invention

[0005] This invention provides a reinforced PPR pipe to solve the above-mentioned problems.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A reinforced PPR pipe comprises the following raw materials in parts by weight: 100 parts PPR resin, 2-5 parts coloring masterbatch, 0.5-1.2 parts topological network nucleating agent, 0.3-0.8 parts hyperbranched polymer-grafted nano silica, and 8-12 parts elastomer.

[0007] The topological network nucleating agent is a carboxyl-terminated polyethylene glycol grafted β-nucleating agent (HOOC-PEG8000-COO-TMB5)@polydopamine / graphene oxide quantum dot composite, with a PEG molecular weight range of 7000-9000 and a β-nucleating agent loading of 15-25 wt%. Its mechanism of action is as follows: the flexible PEG chain promotes the movement of PPR molecular chains and reduces the nucleation barrier; GOQD provides a large number of nucleation sites, greatly increasing the nucleation density; and PDA enhances the interfacial bonding with the matrix.

[0008] The hyperbranched polymer-grafted nano-silica consists of composite particles formed by covalently grafting hyperbranched polyethyleneimine (HPEI) onto the surface of nano-silica, with a particle size of 30-80 nm, a grafting rate of 5-15 wt%, and a specific surface area of ​​120-200 m². 2 / g; A three-dimensional dendritic topology is formed on the surface of nano-SiO2 by grafting with HPEI. The numerous amino groups at the ends of the dendritic structure form multi-point physical entanglement and hydrogen bond interactions with the PPR molecular chains, providing a three-dimensional nucleation template for β crystals.

[0009] The elastomer is preferably one or more of polyolefin elastomer (POE), thermoplastic elastomer (TPE), or ethylene propylene diene monomer (EPDM).

[0010] Based on the above technical solutions, the present invention also provides the following optional technical solutions: In one alternative, the following raw materials are included in parts by weight: 100 parts PPR resin, 3-4.5 parts coloring masterbatch, 0.6-1.1 parts topological network nucleating agent, 0.4-0.7 parts hyperbranched polymer-grafted nano silica, and 9-11 parts elastomer.

[0011] In one alternative, the following raw materials are included in parts by weight: 100 parts PPR resin, 3.5 parts coloring masterbatch, 0.85 parts topological network nucleating agent, 0.55 parts hyperbranched polymer-grafted nano silica, and 10 parts elastomer.

[0012] In one alternative approach, the preparation method of the topological network-type nucleating agent is as follows: Terminal carboxyl polyethylene glycol (HOOC-PEG8000-COOH) and a β-nucleating agent were dissolved in tetrahydrofuran at a mass ratio of 1:0.18-0.22. A dicyclohexylcarbodiimide (DCC) catalyst was added, and the reaction was carried out at 35-40℃ for 4-6 hours to obtain the graft. The β-nucleating agent can be one or more of aryl amides (such as TMB-5), rare earth elements (such as WBG-2), or bicyclic carboxylic acid metal salts. Graphene quantum dots (GOQD) with a particle size of 3-10 nm and a concentration of 1 mg / mL were dispersed with grafts at a mass ratio of 1:8-10 in a buffer solution (such as 10 mmol / L Tris-HCl buffer) at pH 8.5. Dopamine hydrochloride (DA) was added, with a DA to GOQD mass ratio of 1:1. The mixture was allowed to self-polymerize at 25 °C for 24 h to form a PEG-TMB5@PDA / GOQD composite. After centrifugation and drying, the powder is sieved to obtain a particle size of 0.5-5 μm.

[0013] In one alternative approach: the method for preparing the hyperbranched polymer-grafted nano-silica includes the following steps: (a) Surface epoxy treatment: 8-12 parts by weight of nano-silica (particle size 20-50 nm, specific surface area >150 m²) 2 / g) is dispersed in 80-120 parts by weight of anhydrous ethanol, and γ-glycidyl etheroxypropyltrimethoxysilane (GPS) accounting for 20%-30% of the mass of nano silica is added. The pH is adjusted to 4-5 with acetic acid, and the reaction is refluxed at 60-70℃ for 5-7 hours. After centrifugation and drying, nano silica with surface-grafted epoxy groups (SiO2-GPS) is obtained. (b) Hyperbranched polymer grafting: The nano-silica with surface-grafted epoxy groups obtained in step (a) is dispersed in 80-120 parts by weight of N,N-dimethylformamide (DMF), and hyperbranched polyethyleneimine (HPEI, molecular weight 5000-10000) is added in a mass ratio of 1:1 to 1:1.5 with the nano-silica with surface-grafted epoxy groups. The reaction is carried out at 75-85℃ for 10-14 hours under nitrogen protection, centrifuged, washed 3 times with ethanol, and vacuum dried at 60-70℃ for 10-14 hours to obtain hyperbranched polyethyleneimine grafted nano-silica.

[0014] In one alternative embodiment, the coloring masterbatch comprises the following components: 1-5 wt% pigment, 10-60 wt% titanium dioxide, 0.5-1 wt% antioxidant (such as 1010, 168), 1-5 wt% dispersant (such as calcium stearate, polyethylene wax), and the balance being a PP / PE carrier, wherein the PP / PE carrier is a polypropylene homopolymer or low-density polyethylene.

[0015] The present invention also provides a method for preparing the above-mentioned reinforced PPR pipe, comprising the following steps: (1) Melt extrusion molding: PPR resin, coloring masterbatch, topological network nucleating agent, hyperbranched polymer grafted nano silica and elastomer are mixed evenly and melt extruded at 195-205℃. After conventional cooling and shaping, they are cut into fixed length pipe sections. (2) Annealing treatment: Place the fixed-length pipe section in a hot air circulating annealing device, heat it to 90-110℃ and keep it at that temperature for 5-15 minutes; (3) Gradient slow cooling: The tube section after annealing is slowly cooled from the annealing temperature to 40℃ at a rate of ≤5℃ / min to provide sufficient time for the growth and perfection of β crystals; (4) Final cooling: Allow to cool naturally to room temperature.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention achieves high β-crystal content through the synergistic effect of a topological network nucleating agent and hyperbranched polymer-grafted nano-silica. The topological network nucleating agent provides high-density chemical nucleation sites in the bulk matrix, while the hyperbranched grafted nano-silica forms an ordered molecular adsorption layer with β-crystal orientation on the particle surface, serving as a three-dimensional geometric nucleation template. The two complement each other spatially, generating a cascade nucleation effect, which significantly increases the density of β-crystal nucleation sites, ultimately resulting in PPR pipes that simultaneously possess high ring stress strength and excellent impact toughness. Attached Figure Description

[0017] Figure 1 This invention provides a flowchart of a method for preparing reinforced PPR pipes. Detailed Implementation

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0019] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0020] Example 1 This invention provides a reinforced PPR pipe comprising the following raw materials in parts by weight: 100 parts PPR resin, 2 parts coloring masterbatch, 0.5 parts topological network nucleating agent, 0.3 parts hyperbranched polymer-grafted nano silica, and 8 parts elastomer (POE).

[0021] The preparation method of the topological network nucleating agent is as follows: Carboxyl-terminated polyethylene glycol (HOOC-PEG8000-COOH) and β-nucleating agent (TMB-5) were dissolved in tetrahydrofuran at a mass ratio of 1:0.2. Dicyclohexylcarbodiimide (DCC) catalyst was added, and the reaction was carried out at 38°C for 5 hours to obtain the grafted product. Graphene quantum dots (GOQD) with a particle size of 3-10 nm and a concentration of 1 mg / mL were dispersed with grafts at a mass ratio of 1:9 in Tris-HCl buffer at pH 8.5. Dopamine hydrochloride (DA) was added, with a DA to GOQD mass ratio of 1:1. The mixture was allowed to self-polymerize at 25 °C for 24 h to form a PEG-TMB5@PDA / GOQD composite. After centrifugation and drying, the powder was sieved to obtain a particle size of 2.5 μm.

[0022] The preparation method of the hyperbranched polymer-grafted nano-silica is as follows: (a) Surface epoxy treatment: 8 parts by weight of nano-silica (particle size 30 nm, specific surface area 180 m²) 2 / g) was dispersed in 80 parts by weight of anhydrous ethanol, and GPS accounting for 20% of the mass of nano silica was added. The pH was adjusted to 4-5 with acetic acid, and the reaction was refluxed at 65°C for 6 hours. After centrifugation and drying, SiO2-GPS was obtained. (b) Hyperbranched polymer grafting: The SiO2-GPS obtained in step (a) was dispersed in 80 parts by weight of DMF, and hyperbranched polyethyleneimine (HPEI, molecular weight 8000) with a mass ratio of 1:1 to SiO2-GPS was added. The reaction was carried out at 80°C for 12 hours under nitrogen protection, centrifuged, washed three times with ethanol, and vacuum dried at 65°C for 12 hours to obtain SiO2-g-HPEI. The particle size of the obtained SiO2-g-HPEI was 45 nm, the grafting rate was 8.5 wt%, and the specific surface area was 165 m². 2 / g.

[0023] This invention also provides a method for preparing the above-mentioned reinforced PPR pipe, comprising the following steps: (1) Melt extrusion molding: The raw materials are mixed evenly, melt extruded at 195°C, and then cooled and shaped by conventional methods and cut into fixed-length pipe sections; (2) Annealing treatment: Place the fixed-length pipe section in a hot air circulating annealing device, heat it to 90°C and keep it at that temperature for 5 minutes; (3) Gradient slow cooling: The annealed pipe section is slowly cooled from the annealing temperature to 40℃ at a rate of 5℃ / min; (4) Final cooling: Allow to cool naturally to room temperature.

[0024] Example 2 This invention provides a reinforced PPR pipe comprising the following raw materials in parts by weight: 100 parts PPR resin, 3 parts coloring masterbatch, 0.6 parts topological network nucleating agent, 0.4 parts hyperbranched polymer-grafted nano silica, and 9 parts elastomer (POE).

[0025] The preparation method of the topological network nucleating agent is the same as in Example 1.

[0026] The preparation method of the hyperbranched polymer-grafted nano-silica is as follows: (a) Surface epoxy treatment: 9 parts by weight of nano silica were dispersed in 90 parts by weight of anhydrous ethanol, GPS accounting for 22% of the mass of nano silica was added, the pH was adjusted to 4-5 with acetic acid, the reaction was refluxed at 65°C for 6 hours, and the product was centrifuged and dried to obtain SiO2-GPS. (b) Hyperbranched polymer grafting: The SiO2-GPS obtained in step (a) was dispersed in 90 parts by weight of DMF, and hyperbranched polyethyleneimine (HPEI, molecular weight 8000) with a mass ratio of 1:1.1 to SiO2-GPS was added. The reaction was carried out at 80°C for 12 hours under nitrogen protection, centrifuged, washed three times with ethanol, and vacuum dried at 65°C for 12 hours to obtain SiO2-g-HPEI. The particle size of the obtained SiO2-g-HPEI was 50 nm, the grafting rate was 9.2 wt%, and the specific surface area was 158 m². 2 / g.

[0027] The preparation method is the same as in Example 1, wherein the extrusion temperature is 198℃, the annealing temperature is 95℃, the holding time is 8 minutes, and the gradient cooling rate is 4℃ / min.

[0028] Example 3 This invention provides a reinforced PPR pipe comprising the following raw materials in parts by weight: 100 parts PPR resin, 3.5 parts coloring masterbatch, 0.85 parts topological network nucleating agent, 0.55 parts hyperbranched polymer-grafted nano silica, and 10 parts elastomer (POE).

[0029] The preparation method of the topological network nucleating agent is the same as in Example 1.

[0030] The preparation method of the hyperbranched polymer-grafted nano-silica is as follows: (a) Surface epoxy treatment: 10 parts by weight of nano silica were dispersed in 100 parts by weight of anhydrous ethanol, GPS accounting for 25% of the mass of nano silica was added, the pH was adjusted to 4-5 with acetic acid, the reaction was refluxed at 65°C for 6 hours, and the product was centrifuged and dried to obtain SiO2-GPS. (b) Hyperbranched polymer grafting: The SiO2-GPS obtained in step (a) was dispersed in 100 parts by weight of DMF, and hyperbranched polyethyleneimine (HPEI, molecular weight 8000) with a mass ratio of 1:1.2 to SiO2-GPS was added. The reaction was carried out at 80°C for 12 hours under nitrogen protection, centrifuged, washed three times with ethanol, and vacuum dried at 65°C for 12 hours to obtain SiO2-g-HPEI. The particle size of the obtained SiO2-g-HPEI was 52 nm, the grafting rate was 10.5 wt%, and the specific surface area was 152 m². 2 / g.

[0031] The preparation method is the same as in Example 1, wherein the extrusion temperature is 200℃, the annealing temperature is 100℃, the holding time is 10 minutes, and the gradient cooling rate is 3℃ / min.

[0032] Example 4 This invention provides a reinforced PPR pipe comprising the following raw materials in parts by weight: 100 parts PPR resin, 4.5 parts coloring masterbatch, 1.1 parts topological network nucleating agent, 0.7 parts hyperbranched polymer-grafted nano silica, and 11 parts elastomer (POE).

[0033] The preparation method of the topological network nucleating agent is the same as in Example 1.

[0034] The preparation method of the hyperbranched polymer-grafted nano-silica is as follows: (a) Surface epoxy treatment: 11 parts by weight of nano silica were dispersed in 110 parts by weight of anhydrous ethanol, GPS accounting for 28% of the mass of nano silica was added, the pH was adjusted to 4-5 with acetic acid, the reaction was refluxed at 65°C for 6 hours, and the product was centrifuged and dried to obtain SiO2-GPS. (b) Hyperbranched polymer grafting: The SiO2-GPS obtained in step (a) was dispersed in 110 parts by weight of DMF, and hyperbranched polyethyleneimine (HPEI, molecular weight 8000) with a mass ratio of 1:1.3 to SiO2-GPS was added. The reaction was carried out at 80°C for 12 hours under nitrogen protection, centrifuged, washed three times with ethanol, and vacuum dried at 65°C for 12 hours to obtain SiO2-g-HPEI. The particle size of the obtained SiO2-g-HPEI was 58 nm, the grafting rate was 11.8 wt%, and the specific surface area was 145 m². 2 / g.

[0035] The preparation method is the same as in Example 1, wherein the extrusion temperature is 203℃, the annealing temperature is 105℃, the holding time is 12 minutes, and the gradient cooling rate is 2℃ / min.

[0036] Example 5 This invention provides a reinforced PPR pipe comprising the following raw materials in parts by weight: 100 parts PPR resin, 5 parts coloring masterbatch, 1.2 parts topological network nucleating agent, 0.8 parts hyperbranched polymer-grafted nano silica, and 12 parts elastomer (POE).

[0037] The preparation method of the topological network nucleating agent is the same as in Example 1.

[0038] The preparation method of the hyperbranched polymer-grafted nano-silica is as follows: (a) Surface epoxy treatment: 12 parts by weight of nano silica were dispersed in 120 parts by weight of anhydrous ethanol, GPS accounting for 30% of the mass of nano silica was added, the pH was adjusted to 4-5 with acetic acid, the reaction was refluxed at 65°C for 6 hours, and the product was centrifuged and dried to obtain SiO2-GPS. (b) Hyperbranched polymer grafting: The SiO2-GPS obtained in step (a) was dispersed in 120 parts by weight of DMF, and hyperbranched polyethyleneimine (HPEI, molecular weight 8000) with a mass ratio of 1:1.5 to SiO2-GPS was added. The reaction was carried out at 80°C for 12 hours under nitrogen protection, centrifuged, washed three times with ethanol, and vacuum dried at 65°C for 12 hours to obtain SiO2-g-HPEI. The particle size of the obtained SiO2-g-HPEI was 65 nm, the grafting rate was 13.5 wt%, and the specific surface area was 138 m². 2 / g.

[0039] The preparation method is the same as in Example 1, wherein the extrusion temperature is 205℃, the annealing temperature is 110℃, the holding time is 15 minutes, and the gradient cooling rate is 1℃ / min.

[0040] Example 6 This invention provides a reinforced PPR pipe comprising the following raw materials in parts by weight: 100 parts PPR resin, 3.5 parts coloring masterbatch, 0.85 parts topological network nucleating agent, 0.55 parts hyperbranched polymer-grafted nano silica, and 10 parts elastomer (EPDM).

[0041] The difference between the preparation method of the topological network nucleating agent and that in Example 3 is that HOOC-PEG7000-COOH is used instead of HOOC-PEG8000-COOH, while the rest are the same.

[0042] The preparation method of the hyperbranched polymer-grafted nano-silica is the same as in Example 3.

[0043] The preparation method is the same as in Example 3.

[0044] Performance test results: β crystal content 86.2%, hydrostatic strength qualified, impact strength at -20℃ 8.0 kJ / m 2 The performance trend is consistent with that of Example 3.

[0045] Comparative Example 1: The difference from Example 3 is that an equal amount of ordinary β-nucleating agent TMB-5 was used instead of the topological network nucleating agent (i.e., ordinary TMB-5 + hyperbranched polymer grafted nano silica).

[0046] Comparative Example 2: The difference from Example 3 is that hyperbranched polymer-grafted nano-silica (i.e., topological network nucleating agent alone) was not used.

[0047] Comparative Example 3: The difference from Example 3 is that an equal amount of ungrafted modified ordinary nano silica was used instead of hyperbranched polymer-grafted nano silica (i.e., topological network nucleating agent + ordinary nano SiO2).

[0048] Comparative Example 4: The difference from Example 3 is that an equal amount of ordinary TMB-5 was used instead of the topological network nucleating agent, and an equal amount of ungrafted ordinary nano silica was used instead of hyperbranched polymer-grafted nano silica (i.e., ordinary TMB-5 + ordinary nano SiO2).

[0049] Comparative Example 5: The difference from Example 3 is that an equal amount of hyperbranched polymer grafted nano-silica was used, but no topological network nucleating agent was used and no other β-nucleating agent was used (i.e., hyperbranched grafted SiO2 alone).

[0050] Comparative Example 6: The difference from Example 3 is that an equal amount of ordinary TMB-5 was used instead of the topological network nucleating agent, and no nano silica (i.e., ordinary TMB-5 alone) was used.

[0051] Comparative Example 7: Ordinary PPR pipes.

[0052] Performance testing Test methods and standards β crystal content (%): According to GB / T 19466.3, differential scanning calorimetry (DSC) was used for testing and calculation; based on the melting peak area obtained by the test, the β crystal content (Xβ) was calculated by the following formula: Xβ = ΔHβ / (ΔHβ+ΔHα)×100%, where ΔHβ and ΔHα are the melting enthalpies of β crystal and α crystal, respectively; in the calculation, the melting enthalpy of β crystal was taken as 177 J / g.

[0053] Hydrostatic strength: The test was conducted according to GB / T 6111. The medium inside and outside the specimen was water. A type A end cap was used. The test conditions were as follows: At 20℃ for 1 hour, the hoop stress was 16.0 MPa. At 95℃ for 22 hours, the ring stress was 4.3 MPa. At 95℃ for 165 hours, the hoop stress is 3.8 MPa. At 95℃ and for 1000 hours, the hoop stress is 3.5 MPa. Three samples were tested under each test condition, and the result was considered qualified if there was no cracking or leakage.

[0054] Notched impact strength of simply supported beam (kJ / m) 2(-20℃): Tested according to GB / T 1043.1 standard; the sample is taken axially from the pipe wall and processed into standard size, using a single-sided V-shaped notch with a notch depth of 2.0 mm and a notch root radius of 0.25 mm; during the low temperature test, the sample is placed in a -20℃ constant temperature chamber for at least 4 hours, and the impact test is completed within 15 seconds after being removed from the constant temperature chamber to evaluate the impact toughness of the pipe under low temperature conditions.

[0055] The test results are shown in Table 1 below: Table 1 Performance test data for each embodiment and comparative example The test data above show that there is a significant synergistic effect between the topological network nucleating agent and the hyperbranched polymer-grafted nano-silica, achieving a breakthrough effect of 1+1>2.

[0056] Comparative Example 7 had a β-crystal content of only 10.0% and an impact strength of 2.2 kJ / m at -20℃. 2 This represents the benchmark level for ordinary PPR pipes.

[0057] The β crystal content and -20°C impact strength of Comparative Example 6 were significantly lower than those of all other examples.

[0058] The β crystal content of Comparative Example 5 was only 21.0%, which was much lower than that of the sample containing β nucleating agent. This indicates that it does not have effective β nucleation ability when used alone. It can only play its role as a three-dimensional nucleation template when used in synergy with topological network nucleating agent.

[0059] Comparative Example 2 had a β-crystal content of 74.5%, passed hydrostatic strength tests, and had an impact strength of 4.0 kJ / m at -20℃. 2 This indicates that topological network nucleating agents have excellent β-crystal nucleation capabilities, but their performance still has room for improvement when used alone.

[0060] Comparative Example 3 had a β-crystal content of 78.0%, passed the hydrostatic strength test, and had an impact strength of 5.0 kJ / m at -20℃. 2 Although it is an improvement over Comparative Example 2, the improvement is limited, and there is no obvious synergistic effect between ordinary nano-silica and topological network nucleating agents.

[0061] The β crystal content of Comparative Example 1 was 71.0%, which was significantly lower than that of Example 3 (87.0%), indicating that the structural advantage of the topological network nucleating agent is the key to the synergistic effect.

[0062] The β-crystal content of Comparative Example 4 was 62.0%, indicating that the combination effect of ordinary nano-silica and ordinary TMB-5 is limited.

[0063] Example 3: β crystal content (87.0%), -20℃ impact strength (7.5 kJ / m). 2 The results were significantly higher than all comparative examples, and the hydrostatic strength was qualified, proving that there is a significant synergistic effect between the topological network nucleating agent and the hyperbranched polymer-grafted nano-silica.

[0064] This invention utilizes a "dual-network synergistic nucleation system" composed of a topological network nucleating agent and hyperbranched polymer-grafted nano-silica. The various technical features support each other and synergistically enhance each other, jointly achieving a breakthrough improvement in the β-crystal content, mechanical strength, and toughness of PPR pipes.

[0065] It should be noted that, for the sake of simplicity, the foregoing embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0066] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on these embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

Claims

1. An enhanced ppr pipe, characterized by, The raw materials include the following by weight: 100 parts PPR resin, 2-5 parts coloring masterbatch, 0.5-1.2 parts topological network nucleating agent, 0.3-0.8 parts hyperbranched polymer grafted nano silica, and 8-12 parts elastomer. The topological network nucleating agent is a carboxyl-terminated polyethylene glycol grafted β-nucleating agent@polydopamine / graphene oxide quantum dot composite. The hyperbranched polymer-grafted nano-silica is a composite particle formed by covalently grafting hyperbranched polyethyleneimine onto the surface of nano-silica.

2. The reinforced ppr pipe according to claim 1, characterized in that, It includes the following raw materials in parts by weight: 100 parts PPR resin, 3-4.5 parts coloring masterbatch, 0.6-1.1 parts topological network nucleating agent, 0.4-0.7 parts hyperbranched polymer-grafted nano silica, and 9-11 parts elastomer.

3. The reinforced PPR pipe as claimed in claim 1, wherein, The raw materials include the following by weight: 100 parts PPR resin, 3.5 parts coloring masterbatch, 0.85 parts topological network nucleating agent, 0.55 parts hyperbranched polymer-grafted nano silica, and 10 parts elastomer.

4. The reinforced PPR pipe as claimed in claim 1, wherein, The PEG molecular weight range of the topological network nucleating agent is 7000-9000, and the β nucleating agent loading is 15-25wt%.

5. The reinforced ppr pipe according to claim 4, characterized in that, The preparation method of the topological network nucleating agent is as follows: Terminal carboxyl polyethylene glycol and β-nucleating agent were dissolved in tetrahydrofuran at a mass ratio of 1:(0.18-0.22) and reacted at 35-40℃ for 4-6 hours under the action of dicyclohexylcarbodiimide catalyst to obtain the grafted product. Graphene oxide quantum dots and the grafted material were dispersed in a buffer solution at pH 8.5 at a mass ratio of 1:(8-10). Dopamine hydrochloride was added, and the mass ratio of dopamine hydrochloride to graphene oxide quantum dots was 1:

1. The mixture was then self-polymerized at 25°C for 24 hours to form the topological network nucleating agent complex. After centrifugation and drying, a powdered product is obtained.

6. The reinforced PPR pipe as claimed in claim 1, wherein, The hyperbranched polymer-grafted silica nanoparticles have a particle size of 30-80 nm, a grafting rate of 5-15 wt%, and a specific surface area of ​​120-200 m². 2 / g, of which the molecular weight of hyperbranched polyethyleneimine is 5000-10000.

7. The reinforced PPR pipe as claimed in claim 1, wherein, The preparation method of the hyperbranched polymer-grafted nano-silica is as follows: (a) Surface epoxyation: Disperse nano-silica in anhydrous ethanol, add γ-glycidyl etheroxypropyltrimethoxysilane, reflux at 60-70℃ for 5-7 hours, centrifuge and dry to obtain nano-silica with surface-grafted epoxy groups. (b) Hyperbranched polymer grafting: The product obtained in step (a) is dispersed in N,N-dimethylformamide, hyperbranched polyethyleneimine is added, and the mixture is reacted at 75-85℃ for 10-14 hours under nitrogen protection. After centrifugation, washing and drying, hyperbranched polyethyleneimine-grafted nano silica is obtained.

8. The reinforced PPR pipe as claimed in claim 1, wherein, The coloring masterbatch contains the following components: 1-5 wt% pigment, 10-60 wt% titanium dioxide, 0.5-1 wt% antioxidant, 1-5 wt% dispersant, and the balance being PP / PE carrier.

9. A method of producing a reinforced ppr pipe according to any one of claims 1 to 8, characterized by, Includes the following steps: (1) Melt extrusion molding: PPR resin, coloring masterbatch, topological network nucleating agent, hyperbranched polymer grafted nano silica and elastomer are mixed evenly and melt extruded at 195-205℃. After conventional cooling and shaping, they are cut into fixed length pipe sections. (2) Annealing treatment: Place the fixed-length pipe section in a hot air circulating annealing device, heat it to 90-110℃ and keep it at that temperature for 5-15 minutes; (3) Gradient slow cooling: The annealed pipe section is slowly cooled from the annealing temperature to 40℃ at a rate of ≤5℃ / min; (4) Final cooling: Allow to cool naturally to room temperature.

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