Silane crosslinked polyethylene pipeline with chlorine resistance and UV resistance and preparation method thereof

Abstract

The invention discloses an anti-chlorine and anti-UV silane crosslinked polyethylene pipeline and a preparation method thereof, and belongs to the technical field of plastic pipes. The components of the inner wall layer are optimized, the added chlorine-resistant master batch is obtained by compounding the modified filler and the high-molecular polymer supported amine compound, the amine compound can effectively react with free chlorine, and the hydrotalcite modified by the silane coupling agent can effectively react with free chlorine by reducing the chloride ion permeation route. Nano titanium dioxide plays a remarkable anti-chlorine effect through intercalation surface complexation in a chemical and physical combined mode, and specific high-molecular polymer supported amine compounds can effectively prevent functional components from migrating and separating out towards the interior of a pipeline under long-term washing of water flow, so that the durability of the anti-chlorine effect is improved. On the whole, through a sandwich structure with the chlorine resistance of the inner wall layer, the enhancement of the middle layer and the ultraviolet resistance and weather resistance of the outer wall layer, the application strength and remarkable UV resistance of the pipeline are guaranteed, and the safety of long-term use of the pipeline is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of plastic pipe technology, and more specifically, to a silane cross-linked polyethylene pipe with chlorine and UV resistance and its preparation method. Background Technology

[0002] Polyethylene (PE) is one of the most widely used general-purpose plastics. It possesses excellent chemical stability (virtually insoluble in any solvent at room temperature), low-temperature toughness, ease of processing, and low cost, making it widely used in many areas of industrial production and daily life. However, the polyethylene molecule contains only two elements, C and H, with the molecular formula -CH2-CH2- and a linear molecular chain. Due to these structural characteristics, polyethylene cannot withstand high temperatures, and its poor mechanical strength and resistance to environmental stress cracking limit its use in many fields. In particular, PE pipes fail to meet the requirements for hot and cold water transportation pipelines in buildings due to their temperature and pressure resistance, environmental stress cracking resistance, weather resistance, oil resistance, and creep resistance. Therefore, modifying polyethylene through physical and chemical means to improve certain properties or endow it with new properties has become an important issue that needs to be addressed.

[0003] Chlorine or chloramine is commonly used as a disinfectant in municipal tap water. Residual free chlorine can penetrate into the interior of PEX pipes, attacking the polyethylene molecular chains. Especially under the synergistic effect of hot water, this accelerates the oxidative degradation of the polymer (i.e., chlorine stress cracking), leading to decreased pipe strength, cracking, and even pipe bursts, seriously threatening the long-term safety of the system. Furthermore, PEX material itself is extremely sensitive to ultraviolet (UV) radiation. During transportation, storage, or outdoor installation, exposure to sunlight for a period of time can cause UV radiation to break its polymer chains, resulting in surface powdering and embrittlement, and a sharp decline in mechanical properties (such as impact resistance and pressure resistance), significantly shortening its service life. Existing PEX pipes are mostly single-layer or double-layer structures, making it difficult to simultaneously meet the composite functional requirements of an inner wall chlorine resistance, an outer wall UV resistance, and a high-strength intermediate layer.

[0004] Although some studies have attempted to improve a certain performance by adding additives, they often sacrifice other performances or involve complex processes and high costs, failing to achieve a synergistic improvement in overall performance. Summary of the Invention

[0005] Based on this, in order to solve one of the above-mentioned technical problems, the present invention provides a silane cross-linked polyethylene pipe with chlorine and UV resistance and its preparation method, the specific technical solution of which is as follows:

[0006] A silane cross-linked polyethylene pipe with chlorine and UV resistance, the silane cross-linked polyethylene pipe comprising, from the inside to the outside, an inner wall layer, an intermediate layer and an outer wall layer, wherein the inner wall layer has chlorine resistance, the intermediate layer has high strength and the outer wall layer has UV resistance.

[0007] Furthermore, the inner wall layer comprises the following raw materials in parts by weight: 100 parts of high-density polyethylene resin, 1 to 5 parts of chlorine-resistant masterbatch, and 1 to 5 parts of auxiliary antioxidant.

[0008] Furthermore, the chlorine-resistant masterbatch is composed of modified filler and polymer-supported amine compound, and the mass ratio of the filler to the polymer-supported amine compound is (1~10):(7~15).

[0009] Furthermore, the modified filler is obtained by mixing hydrotalcite and nano-titanium dioxide in a mass ratio of (2~5):(5~10) and then modifying it with a silane coupling agent.

[0010] Further, the preparation method of the polymer-supported amine compound is as follows: high-density polyethylene, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, diethylenetriamine, maleic anhydride-grafted polyethylene, and zinc stearate are added to a twin-screw extruder, melt extruded at a temperature of 150℃~200℃, granulated, and dried at 60℃~70℃ for 3h~5h to obtain the polymer-supported amine compound.

[0011] Further, by weight, the high-density polyethylene, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, diethylenetriamine, maleic anhydride-grafted polyethylene and zinc stearate are in the ratio of (40~50):(3~9):(5~15):(1~7):(1~2).

[0012] Furthermore, the intermediate layer is prepared from silane-grafted polyethylene resin, and the degree of crosslinking of the silane-grafted polyethylene resin is 65%~85%.

[0013] Furthermore, the outer wall layer comprises the following raw materials in parts by weight: 100 parts of high-density polyethylene, 1 to 12 parts of UV absorber, 1 to 5 parts of antioxidant, and 1 to 7 parts of light stabilizer.

[0014] Furthermore, the thickness of the inner wall layer and the outer wall layer each accounts for 10% to 20% of the total thickness of the silane cross-linked polyethylene pipe, and the intermediate layer accounts for 60% to 80% of the total thickness of the silane cross-linked polyethylene pipe.

[0015] In addition, the present invention also provides a method for preparing a silane cross-linked polyethylene pipe with chlorine and UV resistance, the preparation method comprising the following steps: S1. Prepare materials for the inner wall layer, intermediate layer, and outer wall layer respectively; S2. Three extruders are used to plasticize and melt the three layers of material respectively to obtain the inner wall layer molten material, the middle layer molten material and the outer wall layer molten material, which are then combined through a co-extrusion die to form a tube blank; S3. The tube blank is sizing, cooled, and solidified to obtain a tube; S4. The pipe is subjected to cross-linking treatment and post-treatment to obtain a silane cross-linked polyethylene pipe with chlorine and UV resistance.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention optimizes the composition of the inner wall layer by adding anti-chlorine masterbatch, which is obtained by compounding modified filler and polymer-supported amine compounds. The amine compounds can effectively react with free chlorine, while the hydrotalcite modified with silane coupling agent reduces the chloride ion penetration route, and the nano-titanium dioxide achieves a significant anti-chlorine effect through the combination of chemical and physical methods through intercalation and surface complexation.

[0017] 2. The addition of specific polymer-supported amine compounds in this invention can effectively prevent the functional components from migrating and precipitating into the pipe under long-term water flow, which is beneficial to improving the durability of the anti-chlorine effect.

[0018] 3. This invention utilizes a "sandwich" structure with an inner chlorine-resistant layer, a middle reinforcement layer, and an outer UV-resistant and weather-resistant layer. Overall, this not only ensures the application strength and significant UV resistance of the pipeline, reducing the risk of brittle fracture caused by photoaging, but also significantly improves chlorine resistance, ensuring the safety of the pipeline for long-term use. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to its embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the scope of protection of the invention.

[0020] 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 invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0021] According to one embodiment of the present invention, a silane cross-linked polyethylene pipe with chlorine and UV resistance is provided. The silane cross-linked polyethylene pipe includes an inner wall layer, an intermediate layer and an outer wall layer from the inside to the outside. The inner wall layer has chlorine resistance, the intermediate layer has high strength and the outer wall layer has UV resistance.

[0022] In one embodiment, the inner wall layer comprises the following raw materials in parts by weight: 100 parts of high-density polyethylene resin, 1 to 5 parts of chlorine-resistant masterbatch, and 1 to 5 parts of auxiliary antioxidant.

[0023] In one embodiment, the chlorine-resistant masterbatch is composed of a modified filler and a polymer-supported amine compound, and the mass ratio of the filler to the polymer-supported amine compound is (1~10):(7~15).

[0024] In one embodiment, the modified filler is obtained by mixing hydrotalcite and nano-titanium dioxide in a mass ratio of (2~5):(5~10) and then modifying the mixture with a silane coupling agent. The present invention, by modifying the hydrotalcite and nano-titanium dioxide, effectively improves their dispersibility and stability. Furthermore, the modification introduces functional groups onto the filler surface, enabling them to form chemical bonds with the polyethylene matrix and exhibiting higher compatibility.

[0025] In one embodiment, the silane coupling agent is at least one of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(β-methoxyethoxy)silane, and tris(3-trimethoxysilylpropyl)isocyanurate.

[0026] In one embodiment, the hydrotalcite is hydrotalcite nanosheets with an aspect ratio of 10-50 and a thickness of 50 nm-150 nm. This invention utilizes hydrotalcite nanosheets with a large aspect ratio in a polyethylene matrix, exhibiting a highly ordered orientation structure that extends the permeation paths of oxygen and water vapor, thereby blocking them. Furthermore, the alternating layers of hydrotalcite nanosheets indirectly contribute to a certain degree of chlorine resistance. Additionally, combined with the synergistic effect of nano-titanium dioxide, In one embodiment, the preparation method of the polymer-supported amine compound is as follows: high-density polyethylene, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, diethylenetriamine, maleic anhydride-grafted polyethylene, and zinc stearate are added to a twin-screw extruder, melt-extruded at a temperature of 150°C to 200°C, granulated, and dried at 60°C to 70°C for 3 to 5 hours to obtain the polymer-supported amine compound. The polymer-supported amine compound of the present invention, loaded onto high-density polyethylene through grafting, can prevent the migration and precipitation of small molecule amine components, thus ensuring the long-term effectiveness of the anti-chlorine function to a certain extent. Furthermore, adding the polymer-supported amine compound to the inner wall layer of this application results in more uniform dispersion and compatibility than directly adding amine compounds to the inner wall layer, without causing interface defects or a decrease in mechanical properties, thus helping to improve the performance of the inner wall layer.

[0027] In one embodiment, the high-density polyethylene, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, diethylenetriamine, maleic anhydride-grafted polyethylene and zinc stearate are in the following weight ratios: (40~50):(3~9):(5~15):(1~7):(1~2).

[0028] In one embodiment, the auxiliary antioxidant is at least one of hydroquinone, hydroquinone, and pentaerythritol tetrakis(β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate).

[0029] In one embodiment, the intermediate layer is prepared from silane-grafted polyethylene resin, and the degree of crosslinking of the silane-grafted polyethylene resin is 65% to 85%.

[0030] In one embodiment, the outer wall layer comprises the following raw materials in parts by weight: 100 parts of high-density polyethylene, 1 to 12 parts of UV absorber, 1 to 5 parts of antioxidant, and 1 to 7 parts of light stabilizer.

[0031] In one embodiment, the UV absorber is at least one of diphenyl ketone, 2-hydroxy-4-methoxybenzophenone, [2-hydroxy-4-(octoxy)phenyl]phenyl ketone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, benzophenone-12, benzophenone-12, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, and benzophenone-12.

[0032] In one embodiment, the antioxidant is at least one of 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzyl, ethylidene bis[3,3-bis(3-tert-butyl-4-hydroxyphenyl)butyrate], and 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-isocyanurate.

[0033] In one embodiment, the light stabilizer is at least one of light stabilizer 770 and light stabilizer 944. The addition of a UV absorber and a light stabilizer to the outer wall layer of this invention constitutes a robust "sunscreen shell." The UV absorber effectively shields and converts ultraviolet light energy, while the light stabilizer quenches free radicals excited by ultraviolet light. The synergistic effect of both inhibits the chain reaction of photo-oxidative degradation at its source, enabling the pipeline to effectively resist sunlight exposure during transportation, storage, and outdoor installation, preventing surface powdering, embrittlement, and degradation of mechanical properties, thus greatly expanding the application scenarios and service life of the pipeline.

[0034] In one embodiment, the thickness of the inner wall layer and the outer wall layer each accounts for 10% to 20% of the total thickness of the silane cross-linked polyethylene pipe, and the intermediate layer accounts for 60% to 80% of the total thickness of the silane cross-linked polyethylene pipe.

[0035] In addition, the present invention also provides a method for preparing a silane cross-linked polyethylene pipe with chlorine and UV resistance, the preparation method comprising the following steps: S1. Prepare materials for the inner wall layer, intermediate layer, and outer wall layer respectively; S2. Three extruders are used to plasticize and melt the three layers of material respectively to obtain the inner wall layer molten material, the middle layer molten material and the outer wall layer molten material, which are then combined through a co-extrusion die to form a tube blank; S3. The tube blank is sizing, cooled, and solidified to obtain a tube; S4. The pipe is subjected to cross-linking treatment and post-treatment to obtain a silane cross-linked polyethylene pipe with chlorine and UV resistance.

[0036] In one embodiment, in step S2, the melting temperature is 165°C to 220°C, and the rotation speed is 15 r / min to 150 r / min.

[0037] In one embodiment, in step S4, the humidity of the crosslinking treatment is 45%~65% and the temperature is 80℃~95℃.

[0038] In one embodiment, in step S4, the post-processing involves drying, labeling, cutting to a fixed length, and coiling or straightening the pipe.

[0039] The embodiments of the present invention will be described in detail below with reference to specific examples. Raw materials not limited in this application are understood to be conventional raw materials, all of which can be purchased from the market. Processes not limited are not existing technologies and will not be elaborated upon here.

[0040] Example 1: A method for preparing a silane cross-linked polyethylene pipe with chlorine and UV resistance, the method comprising the following steps: S1. Prepare materials for the inner wall layer, intermediate layer, and outer wall layer respectively; The inner wall layer comprises the following raw materials in parts by weight: 100 parts of high-density polyethylene resin, 3 parts of chlorine-resistant masterbatch, and 2 parts of hydroquinone. The antichlorine masterbatch is composed of modified filler and polymer-supported amine compound in a mass ratio of 8:12. The modified filler is obtained by mixing hydrotalcite and nano titanium dioxide in a mass ratio of 3:5 and then modifying it with vinyltrimethoxysilane. The hydrotalcite has an aspect ratio of 45 and a thickness of 60 nm. The preparation method of the polymer-supported amine compound is as follows: 50 parts by weight of high-density polyethylene, 5 parts by weight of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 9 parts by weight of diethylenetriamine, 5 parts by weight of maleic anhydride-grafted polyethylene, and 1 part by weight of zinc stearate are added to a twin-screw extruder, melt extruded at a temperature of 150℃~200℃, granulated, and dried at 65℃ for 4 hours to obtain the polymer-supported amine compound. The intermediate layer is prepared from silane-grafted polyethylene resin, and the degree of crosslinking of the silane-grafted polyethylene resin is 80%. The outer wall layer comprises the following raw materials in parts by weight: 100 parts of high-density polyethylene, 7 parts of 2-hydroxy-4-methoxybenzophenone, 4 parts of 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene and 7705 parts of light stabilizer. S2. Three extruders are used to plasticize and melt the three layers of material respectively to obtain the inner wall layer molten material, the middle layer molten material and the outer wall layer molten material, which are then combined through a co-extrusion die to form a tube blank; The melting temperature is 165℃~220℃, and the rotation speed is 80r / min; S3. The tube blank is sizing, cooled, and solidified to obtain a tube; S4. The pipe is cross-linked at a humidity of 60% and a temperature of 85°C, and then dried, labeled, cut to length and straightened to obtain a silane cross-linked polyethylene pipe with chlorine and UV resistance.

[0041] Example 2: The difference between Example 2 and Example 1 is that the ratio of raw materials used to prepare the inner wall layer is different; otherwise, they are the same as in Example 1. The inner wall layer described in Example 2 comprises the following raw materials in parts by weight: 100 parts of high-density polyethylene resin, 4 parts of chlorine-resistant masterbatch, and 2 parts of hydroquinone; The antichlorine masterbatch is composed of modified filler and polymer-supported amine compound in a mass ratio of 7:13. The modified filler is obtained by mixing hydrotalcite and nano titanium dioxide in a mass ratio of 3:5 and then modifying it with vinyltrimethoxysilane. The hydrotalcite has an aspect ratio of 45 and a thickness of 60 nm. The preparation method of the polymer-supported amine compound is as follows: 50 parts by weight of high-density polyethylene, 5 parts by weight of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 9 parts by weight of diethylenetriamine, 5 parts by weight of maleic anhydride-grafted polyethylene, and 1 part by weight of zinc stearate are added to a twin-screw extruder, melt extruded at a temperature of 150℃~200℃, granulated, and dried at 65℃ for 4 hours to obtain the polymer-supported amine compound.

[0042] Example 3: The difference between Example 3 and Example 1 is that the ratio of raw materials used to prepare the inner wall layer is different; otherwise, they are the same as in Example 1. The inner wall layer described in Example 3 comprises the following raw materials in parts by weight: 100 parts of high-density polyethylene resin, 5 parts of chlorine-resistant masterbatch, and 2 parts of hydroquinone; The antichlorine masterbatch is composed of modified filler and polymer-supported amine compound in a mass ratio of 9:11. The modified filler is obtained by mixing hydrotalcite and nano titanium dioxide in a mass ratio of 3:5 and then modifying it with vinyltrimethoxysilane. The hydrotalcite has an aspect ratio of 45 and a thickness of 60 nm. The preparation method of the polymer-supported amine compound is as follows: 50 parts by weight of high-density polyethylene, 5 parts by weight of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 9 parts by weight of diethylenetriamine, 5 parts by weight of maleic anhydride-grafted polyethylene, and 1 part by weight of zinc stearate are added to a twin-screw extruder, melt extruded at a temperature of 150℃~200℃, granulated, and dried at 65℃ for 4 hours to obtain the polymer-supported amine compound.

[0043] Example 4: The difference between Example 4 and Example 1 is that the ratio of raw materials used to prepare the inner wall layer is different; otherwise, they are the same as in Example 1. The inner wall layer described in Example 4 comprises the following raw materials in parts by weight: 100 parts of high-density polyethylene resin, 3 parts of chlorine-resistant masterbatch, and 2 parts of hydroquinone; The antichlorine masterbatch is composed of modified filler and polymer-supported amine compound in a mass ratio of 8:12. The modified filler is obtained by mixing hydrotalcite and nano titanium dioxide in a mass ratio of 4:7 and then modifying it with vinyltrimethoxysilane. The hydrotalcite has an aspect ratio of 45 and a thickness of 60 nm. The preparation method of the polymer-supported amine compound is as follows: 50 parts by weight of high-density polyethylene, 7 parts by weight of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 12 parts by weight of diethylenetriamine, 5 parts by weight of maleic anhydride-grafted polyethylene, and 1 part by weight of zinc stearate are added to a twin-screw extruder, melt extruded at a temperature of 150℃~200℃, granulated, and dried at 65℃ for 4 hours to obtain the polymer-supported amine compound.

[0044] Example 5: The difference between Example 5 and Example 1 is that the ratio of raw materials used to prepare the inner wall layer is different; otherwise, they are the same as in Example 1. The inner wall layer described in Example 5 comprises the following raw materials in parts by weight: 100 parts of high-density polyethylene resin, 3 parts of chlorine-resistant masterbatch, and 2 parts of hydroquinone; The antichlorine masterbatch is composed of modified filler and polymer-supported amine compound in a mass ratio of 8:12. The modified filler is obtained by mixing hydrotalcite and nano titanium dioxide in a mass ratio of 3:5 and then modifying it with vinyltrimethoxysilane. The hydrotalcite has an aspect ratio of 50 and a thickness of 80 nm. The preparation method of the polymer-supported amine compound is as follows: 50 parts by weight of high-density polyethylene, 7 parts by weight of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, 15 parts by weight of diethylenetriamine, 6 parts by weight of maleic anhydride-grafted polyethylene, and 2 parts by weight of zinc stearate are added to a twin-screw extruder, melt extruded at a temperature of 150℃~200℃, granulated, and dried at 65℃ for 4 hours to obtain the polymer-supported amine compound.

[0045] Comparative Example 1: The difference between Comparative Example 1 and Example 5 is that the hydrotalcite added in Comparative Example 1 has an aspect ratio of 5 and a thickness of 20.

[0046] Comparative Example 2: The difference between Comparative Example 2 and Example 5 is that the hydrotalcite added in Comparative Example 2 has an aspect ratio of 80 and a thickness of 200 nm.

[0047] Comparative Example 3: The difference between Comparative Example 3 and Example 5 is that the antichlorine masterbatch in Comparative Example 3 did not contain hydrotalcite, while the rest was the same as in Example 5.

[0048] Comparative Example 4: The difference between Comparative Example 4 and Example 5 is that no nano-titanium dioxide was added in Comparative Example 4, but otherwise it is the same as Example 5.

[0049] Comparative Example 5: The difference between Comparative Example 5 and Example 5 is that diethylenetriamine was directly added in Comparative Example 5, while the rest was the same as in Example 5.

[0050] Comparative Example 6: The difference between Comparative Example 6 and Example 5 is that no polymer-supported amine compound was added in Comparative Example 5, but otherwise it is the same as Example 5.

[0051] Comparative Example 7: The difference between Comparative Example 7 and Example 5 is that Comparative Example 7 does not have an outer wall layer, but otherwise it is the same as Example 5.

[0052] I. Chlorine Resistance Test The silane cross-linked polyethylene pipe samples of Examples 1-5 and the silane cross-linked polyethylene pipe samples of Comparative Examples 1-7 were subjected to chloride ion solution immersion experiments: a chloride ion solution with a concentration of 200 ppm was prepared, and pipe samples with a length of 30 cm ± 0.5 cm were immersed in the chloride ion solution under the conditions of constant temperature at 60°C and pH value of 6.6 ± 0.1; before immersion and after 100 days of immersion, the inner layer of the pipe was scraped off as a test sample.

[0053] II. Oxidation induction time The oxidation induction time of the sample was tested according to the standard GB / T19466.6-2009. The temperature was increased to 210℃ at 20℃ / min, held for 3 min, and then the gas was switched to oxygen. The temperature was held for another 5 min after the point of significant exothermic change appeared. The average value was calculated and the results are shown in Table 1 below.

[0054] III. Elongation at break The elongation at break was tested in accordance with GB / T8804.3-2003 standard. After soaking for 100 days, the samples were prepared into pipe specimens by mechanical processing. The test was conducted at 23±2℃ and a test speed of 100mm / min. The results are shown in Table 2.

[0055] IV. Hydrostatic strength The hydrostatic strength test was conducted in accordance with the GB / T6111-2003 standard. The samples were tested after being soaked for 100 days. The test temperature was 80℃, the test time was 165h, and the hydrostatic stress was 5.5MPa. The results are shown in Table 2.

[0056] Table 1: Performance Test Results

[0057] Table 2: Elongation at break and hydrostatic test results

[0058] Analysis of the data in Tables 1 and 2 shows that after optimizing the composition of the inner wall layer, the oxidation induction time before immersion in Examples 1-5 is relatively high, and the decrease in oxidation induction time after immersion is small, indicating excellent chlorine resistance and excellent elongation at break retention, which meets the application requirements of pipes.

[0059] Compared with Example 5, Comparative Examples 1 and 2 had poor dispersion performance of hydrotalcite in the inner wall layer due to improper performance parameters of hydrotalcite, with the aspect ratio being too small or too large. This affected the barrier effect, and the oxidation induction time decreased significantly after soaking, resulting in a worse elongation at break. Comparative Example 3, which indeed contains hydrotalcite, exhibits significantly poorer barrier properties, resulting in a weaker chlorine resistance compared to Example 5, which in turn affects its elongation at break retention rate. Comparative Example 4 lacks nano-titanium dioxide, weakening its synergistic chlorine resistance; although it passes the test, its performance is inferior to Example 5. In Comparative Example 5, the diethylenetriamine was not loaded, leading to some migration after use, which affects its performance and service life after prolonged use. Comparative Example 6 lacks functional components, resulting in significantly worse chlorine resistance compared to Example 5, indicating that the addition of polymer-supported amine compounds in this invention can synergistically work with modified fillers to achieve a superior chlorine resistance effect. Comparative Example 7 lacks an outer wall layer, making its structure incomplete compared to Example 5. It exhibits slight photo-oxidative aging before testing, and lacks the protection of an outer wall layer during the immersion test, resulting in a more significant decline in its chlorine resistance. This demonstrates that in the "sandwich" composite structure of this invention, the outer wall layer not only provides UV protection but also serves as a protective layer, maintaining the long-term performance stability of the middle and inner wall layers.

[0060] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0061] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A silane cross-linked polyethylene pipe with chlorine and UV resistance, characterized in that, The silane cross-linked polyethylene pipe comprises, from the inside out, an inner wall layer, an intermediate layer, and an outer wall layer. The inner wall layer has chlorine resistance, the intermediate layer has high strength, and the outer wall layer has UV resistance.

2. The silane cross-linked polyethylene pipe according to claim 1, characterized in that, The inner wall layer comprises the following raw materials in parts by weight: 100 parts of high-density polyethylene resin, 1 to 5 parts of chlorine-resistant masterbatch, and 1 to 5 parts of auxiliary antioxidant.

3. The silane cross-linked polyethylene pipe according to claim 1, characterized in that, The chlorine-resistant masterbatch is composed of modified filler and polymer-supported amine compound, and the mass ratio of the filler to the polymer-supported amine compound is (1~10):(7~15).

4. The silane cross-linked polyethylene pipe according to claim 3, characterized in that, The modified filler is obtained by mixing hydrotalcite and nano-titanium dioxide in a mass ratio of (2~5):(5~10) and then modifying it with a silane coupling agent.

5. The silane cross-linked polyethylene pipe according to claim 3, characterized in that, The preparation method of the polymer-supported amine compound is as follows: high-density polyethylene, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, diethylenetriamine, maleic anhydride-grafted polyethylene, and zinc stearate are added to a twin-screw extruder, melt extruded at a temperature of 150℃~200℃, granulated, and dried at 60℃~70℃ for 3h~5h to obtain the polymer-supported amine compound.

6. The silane cross-linked polyethylene pipe according to claim 5, characterized in that, The high-density polyethylene, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, diethylenetriamine, maleic anhydride-grafted polyethylene and zinc stearate are in the following proportions by weight: (40~50):(3~9):(5~15):(1~7):(1~2).

7. The silane cross-linked polyethylene pipe according to claim 1, characterized in that, The intermediate layer is prepared from silane-grafted polyethylene resin, and the degree of crosslinking of the silane-grafted polyethylene resin is 65%~85%.

8. The silane cross-linked polyethylene pipe according to claim 1, characterized in that, The outer wall layer comprises the following raw materials in parts by weight: 100 parts of high-density polyethylene, 1 to 12 parts of UV absorber, 1 to 5 parts of antioxidant, and 1 to 7 parts of light stabilizer.

9. The silane cross-linked polyethylene pipe according to claim 1, characterized in that, The thickness of the inner wall layer and the outer wall layer each accounts for 10% to 20% of the total thickness of the silane cross-linked polyethylene pipe, and the intermediate layer accounts for 60% to 80% of the total thickness of the silane cross-linked polyethylene pipe.

10. A method for preparing a silane cross-linked polyethylene pipe with chlorine and UV resistance, characterized in that, The preparation method is used for the silane crosslinked polyethylene pipe according to any one of claims 1 to 9, and the preparation method includes the following steps: S1. Prepare materials for the inner wall layer, intermediate layer, and outer wall layer respectively; S2. Three extruders are used to plasticize and melt the three layers of material respectively to obtain the inner wall layer molten material, the middle layer molten material and the outer wall layer molten material, which are then combined through a co-extrusion die to form a tube blank; S3. The tube blank is sizing, cooled, and solidified to obtain a tube; S4. The pipe is subjected to cross-linking treatment and post-treatment to obtain a silane cross-linked polyethylene pipe with chlorine and UV resistance.

Images