Weather-resistant anti-aging master batch for PE drainage pipe material and preparation and application thereof

Abstract

The application discloses a weather-resistant and anti-aging master batch for PE drainage pipe materials and a preparation method and application thereof, and relates to the technical field of plastic master batches. The master batch comprises the following raw materials in parts by weight: carrier resin 50-60 parts, loaded weather-resistant component 20-25 parts, modified lignin 5-10 parts, compatibility agent 3-6 parts, and lubricant 2-4 parts. The loaded weather-resistant component is mesoporous silica loaded weather-resistant additive. The modified lignin carries long-chain alkyl, aminothiourea group and disulfide bond. The mesoporous silica loaded weather-resistant additive in the application provides long-acting and stable free radical capture and ultraviolet shielding function. The modified lignin plays the roles of auxiliary anti-oxidation, metal ion passivation and damage repair through active functional groups. The two form a complementary and synergistic protective network in a polyethylene matrix, so that the thermal oxygen stability and light stability of the regenerated polyethylene composite material are obviously improved, and the service life of the regenerated polyethylene drainage pipe material is prolonged.

Description

Technical Field

[0001] This invention relates to the field of plastic masterbatch technology, and in particular to a weather-resistant and anti-aging masterbatch for PE drainage pipes, its preparation and application. Background Technology

[0002] Polyethylene (PE) drainage pipes are widely used in municipal drainage and building sewage systems due to their excellent chemical resistance, flexibility, and ease of construction. However, PE pipes exposed to the outdoor environment for extended periods are susceptible to corrosion from ultraviolet radiation, heat, oxygen, and moisture, leading to molecular chain breakage, surface powdering, and a sharp decline in mechanical properties, severely impacting their service life.

[0003] Furthermore, with the advancement of the circular economy, recycled polyethylene (rPE) is increasingly widely used in drainage pipes. However, rPE has a complex origin, and its molecular chains already contain aging defects such as carbonyl groups, peroxide free radicals, and chain breaks generated during previous use or recycling processes. It also often contains impurities such as metal ions and cross-linked gels. These factors make r-PE more susceptible to thermo-oxidative degradation and photo-aging than virgin PE.

[0004] While adding weather-resistant masterbatch can delay further aging of regenerated polyethylene (rPE) to some extent, existing masterbatches are typically prepared by physically mixing small-molecule additives such as antioxidants, UV absorbers, and light stabilizers with polyethylene resin. These small-molecule additives have limited compatibility with the PE matrix and are prone to migration and precipitation during processing, storage, and long-term use, resulting in poor protective performance of the masterbatch. Therefore, providing a highly efficient weather-resistant and anti-aging masterbatch suitable for recycled polyethylene drainage pipes is a pressing technical problem that needs to be solved in this field. Summary of the Invention

[0005] One of the objectives of this invention is to provide a weather-resistant and anti-aging masterbatch for PE drainage pipes, so as to solve the problem of poor protective effect of weather-resistant masterbatch for recycled polyethylene drainage pipes in the prior art.

[0006] The second objective of this invention is to provide a method for preparing the above-mentioned weather-resistant and anti-aging masterbatch for PE drainage pipes.

[0007] The third objective of this invention is to provide the application of the above-mentioned weather-resistant and anti-aging masterbatch for PE drainage pipes.

[0008] The technical problem to be solved by this invention can be achieved through the following technical solution: A weather-resistant and anti-aging masterbatch for PE drainage pipes, comprising the following raw materials by weight: 50-60 parts carrier resin, 20-25 parts loaded weather-resistant component, 5-10 parts modified lignin, 3-6 parts compatibilizer, and 2-4 parts lubricant.

[0009] The supported weathering component is a mesoporous silica-supported weathering additive, with a mass ratio of mesoporous silica to weathering additive of 1:0.5-2. The weathering additive includes antioxidants, ultraviolet absorbers, and light stabilizers, with a mass ratio of antioxidants, ultraviolet absorbers, and light stabilizers of 1-2:0.5-1:0.5-1.

[0010] To address the issues of easy migration and precipitation of small molecule additives, this invention uses mesoporous silica as a carrier to load antioxidants, ultraviolet absorbers, and light stabilizers into its pores. The pores physically bind the small molecule additives, reducing their diffusion rate in the polyethylene matrix and improving their migration and precipitation. Furthermore, the thermal decomposition temperature of the small molecule additives loaded onto the mesoporous silica is significantly increased, which helps improve the stability of the masterbatch during high-temperature processing and enhances its protective effect.

[0011] Furthermore, the antioxidant is at least one of antioxidant 1010, antioxidant 1076, and antioxidant 168.

[0012] Furthermore, the ultraviolet absorber is UV-531 and / or UV-P.

[0013] Furthermore, the light stabilizer is light stabilizer 944.

[0014] Furthermore, the mesoporous silica is SBA-15.

[0015] Furthermore, the preparation steps of the supported weather-resistant component are as follows: Antioxidants, UV absorbers, and light stabilizers are added to acetone and mixed thoroughly. Then, mesoporous silica is added, and the mixture is ultrasonically treated. Finally, the acetone is removed by drying to obtain the supported weather-resistant component.

[0016] Furthermore, the amount of acetone used is 15-25 times the sum of the masses of the antioxidant, ultraviolet absorber, and light stabilizer.

[0017] Furthermore, the ultrasonic treatment temperature is 50-60℃, the ultrasonic time is 0.5-1h, the power is 150-200W, and the frequency is 35-45kHz.

[0018] The modified lignin is the product of alkali lignin undergoing coupling chlorination with chlorosiloxane, followed by nucleophilic substitution reaction with aminothiourea, long-chain alkylamine and 2,2'-dithiodiethylamine.

[0019] Furthermore, the modified lignin carries long-chain alkyl groups, aminothiourea groups, and disulfide bonds.

[0020] Furthermore, the raw materials for preparing the modified lignin include chlorinated lignin, aminothiourea, long-chain alkylamine, and 2,2'-dithiodiethylamine.

[0021] Furthermore, the chlorinated lignin is alkali lignin coupled with chlorosiloxane.

[0022] Furthermore, the chlorosiloxane is at least one selected from 3-chloropropylmethyldiethoxysilane, 3-chloropropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

[0023] Furthermore, the long-chain alkylamine has the structural formula R-NH2, where R is C n H 2n+1 Or C n H2 n+1 -O-CH2CH2CH2, 6≤n≤18 and n is an even number, preferably 6, 8, 10, 12, 14, 16, 18, and more preferably 12, 14, 16, 18.

[0024] Furthermore, the long-chain alkylamine is at least one selected from dodecyl primary amine, tetradecylamine, hexadecylamine, and octadecylamine.

[0025] Furthermore, the modified lignin preparation steps are as follows: S1. Add chlorosiloxane to an ethanol solution, stir evenly, adjust the pH to 4-5 with acetic acid, and continue stirring for 2 hours to obtain a hydrolysate; load alkali lignin powder into a mixer, and spray the hydrolysate onto the lignin surface while stirring, controlling the rotation speed to 500-1500 r / min. After spraying, continue mixing for 5-10 min, and dry at 105℃ for 2 hours to obtain chlorinated lignin. S2. Add chlorinated lignin to N,N-dimethylformamide, stir evenly, and adjust the pH to 9-10 with sodium hydroxide solution. Heat to 60-70℃ and stir for 20 min. Add aminothiourea, long-chain alkylamine and 2,2'-dithiodiethylamine. Stir and react at 80-85℃ for 4-6 h. After the reaction is complete, filter, wash the filter cake with distilled water until the washing liquid is neutral, and finally vacuum dry at 60℃ to constant weight to obtain modified lignin.

[0026] Lignin, as a natural aromatic polymer, is rich in active functional groups such as phenolic hydroxyl groups, alcoholic hydroxyl groups, methoxy groups, and conjugated double bonds in its molecular structure, and has multiple weather-resistant functions. However, unmodified lignin has poor compatibility with polyethylene matrix and is prone to agglomeration and uneven dispersion in non-polar matrix. Not only can it not effectively exert its weather-resistant function, but it will also deteriorate the mechanical properties of the material due to the formation of stress concentration points.

[0027] To address this, the present invention modifies lignin by introducing reactive chlorine atoms onto the lignin surface using a chlorosiloxane coupling agent, which then undergoes a nucleophilic substitution reaction with aminothiourea, long-chain alkylamines, and 2,2'-dithiodiethylamine, thereby obtaining modified lignin grafted with long-chain alkyl groups, aminothiourea groups, and disulfide bonds.

[0028] The long-chain alkyl groups on the surface of modified lignin change the lignin surface from hydrophilic to hydrophobic. The long alkyl chains physically entangle with the polyethylene molecular chains, improving the uniformity of lignin dispersion in the polyethylene matrix and avoiding the agglomeration problem of unmodified lignin. The uniformly dispersed modified lignin can act as a "node" for stress transfer, thereby improving the mechanical properties of the composite material.

[0029] The thiourea groups carried by modified lignin have a good complexing effect on metal ions, which can chelate the residual catalytic metal ions in recycled polyethylene, thereby slowing down the oxidative degradation reaction catalyzed by metal ions and extending the service life of the material. In addition, the disulfide bonds (-SS-) carried by modified lignin are dynamic covalent bonds, which can undergo reversible breakage and recombination under heat or light stimulation. This characteristic can repair the microcracks generated in recycled polyethylene during the aging process and prevent the aging from developing into the interior of the material.

[0030] Furthermore, the amount of chlorosiloxane used in S1 is 0.5-2% of the mass of alkali lignin powder, and the ratio of chlorosiloxane to ethanol solution in the hydrolysate is 0.5-1g:10mL, with the ethanol solution having a mass fraction of 70-90%.

[0031] Furthermore, in S2, the mass ratio of chlorinated lignin, aminothiourea, long-chain alkylamine and 2,2'-dithiodiethylamine is 10:0.5-1.5:2-5:1-2, and the mass fraction of sodium hydroxide solution is 5-10%.

[0032] Furthermore, the carrier resin is a mixture of low-density polyethylene and linear low-density polyethylene in a mass ratio of 1:1-3, wherein the melt index of the low-density polyethylene is 5-10 g / 10 min (190℃ / 2.16 kg) and the melt index of the linear low-density polyethylene is 20-50 g / 10 min (190℃ / 2.16 kg).

[0033] Furthermore, the compatibilizer is maleic anhydride-grafted polyethylene.

[0034] Furthermore, the lubricant is at least one of calcium stearate, magnesium stearate, zinc stearate, PE wax, microcrystalline wax, and stearic acid.

[0035] The above-mentioned method for preparing weather-resistant and anti-aging masterbatch for PE drainage pipes includes the following steps: The carrier resin, loaded weather-resistant component, modified lignin, compatibilizer, and lubricant are added to a mixer and mixed for 10-20 minutes. Then, the mixture is transferred to a twin-screw extruder and extruded and granulated to obtain a weather-resistant and anti-aging masterbatch for PE drainage pipes.

[0036] Furthermore, the processing temperature of the twin-screw extruder barrel is 170-190℃, wherein the temperature of zone one is 170-180℃, the temperature of zone two is 175-185℃, the temperature of zone three is 180-190℃, the temperature of zone four is 180-190℃, and the temperature of zone five is 170-180℃.

[0037] The above-mentioned weather-resistant and anti-aging masterbatch for PE drainage pipes is used in the preparation of PE drainage pipes.

[0038] Furthermore, the weather-resistant and anti-aging masterbatch for PE drainage pipes is used in the preparation of drainage pipes made primarily of recycled polyethylene.

[0039] Furthermore, the recycled polyethylene is recycled plastic granules obtained by sorting, washing, crushing, melting and granulating recycled polyethylene, and its sources include, but are not limited to, waste agricultural film, packaging film, hollow container and pipe recycling materials.

[0040] Because recycled polyethylene has already developed aging defects such as carbonyl groups, peroxide free radicals, and chain breaks during its initial use and recycling processes, and often contains impurities such as metal ions and cross-linked gels, its thermo-oxidative and light stability is significantly lower than that of virgin polyethylene. The weather-resistant and anti-aging masterbatch described in this application, through the synergistic effect of modified lignin and supported weather-resistant components, can effectively solve the problem of rapid aging of recycled polyethylene during secondary processing and long-term use.

[0041] Furthermore, the amount of the weather-resistant and anti-aging masterbatch added to the PE drainage pipe is 4-10% of the mass of recycled polyethylene.

[0042] The beneficial effects of this invention are: 1. This invention solves the industry problem of easy migration and precipitation of small molecule additives by loading weather-resistant additives onto mesoporous silica. Using SBA-15 mesoporous silica as a carrier, antioxidants, ultraviolet absorbers, and light stabilizers are loaded into its regular channels. The physical binding effect of the channels significantly reduces the diffusion rate of additives in the polyethylene matrix, while increasing the thermal decomposition temperature of the additives. This ensures the stability of the masterbatch during high-temperature extrusion processing and achieves sustained and efficient release of weather-resistant additives.

[0043] 2. This invention prepares modified lignin by chemically modifying it, resulting in lignin simultaneously grafted with long-chain alkyl groups, aminothiourea groups, and disulfide bonds. This improves the dispersibility of lignin in a polyethylene matrix and enhances its multiple weather-resistant properties. The long-chain alkyl groups carried by the modified lignin improve its compatibility with polyethylene, the thiourea groups can chelate residual catalytic metal ions in recycled polyethylene, and the dynamic reversible nature of the disulfide bonds endows the material with self-healing capabilities for microcracks. The synergistic effect of these three components not only inhibits the oxidative degradation catalyzed by metal ions but also prevents aging from progressing deeper into the material, significantly extending the service life of recycled polyethylene drainage pipes.

[0044] 3. This invention constructs a weather-resistant and anti-aging system that synergistically enhances the effects of supported weather-resistant components and modified lignin, achieving a dual protection mechanism of passive slow release and active repair. Mesoporous silica-supported weather-resistant additives provide long-lasting and stable free radical capture and UV shielding functions, while modified lignin exerts auxiliary antioxidant, metal ion passivation, and damage repair effects through its active functional groups. The two form a complementary and synergistic protective network within the polyethylene matrix, significantly improving the thermal and oxygen stability and light stability of the recycled polyethylene composite material, thus extending the service life of the recycled polyethylene drainage pipe.

[0045] 4. This invention optimizes the masterbatch formulation by using a blend of low-density polyethylene and linear low-density polyethylene as the carrier resin, combined with maleic anhydride-grafted polyethylene compatibilizer, to ensure uniform dispersion of high-content functional components in recycled polyethylene. Modified lignin, as a natural renewable resource, partially replaces expensive synthetic auxiliaries, reducing masterbatch costs. At the same time, it realizes the resource utilization of agricultural and forestry waste, which is in line with the development trend of circular economy and green manufacturing. Detailed Implementation

[0046] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0047] The following detailed description, in conjunction with specific examples, illustrates that the alkali lignin used in this application is obtained from coniferous wood through alkali dissolution and acid precipitation of coniferous wood refining residue. It was purchased from Shandong Longli Biotechnology Co., Ltd. Preparation Example 1 A modified lignin is prepared by the following steps: S1. Add 0.5g of 3-chloropropylmethyldiethoxysilane to 10mL of 70wt% ethanol solution, stir well, adjust the pH to 4 with acetic acid, and continue stirring for 2h to obtain hydrolysate; put 100g of alkali lignin powder into a mixer, stir at 500r / min while spraying the hydrolysate onto the lignin surface, after spraying, continue mixing for 5min, and dry at 105℃ for 2h to obtain chlorinated lignin; S2. Add 10g of chlorinated lignin to 100mL of N,N-dimethylformamide, stir well, and adjust the pH to 9 with 5wt% sodium hydroxide solution. Heat to 60℃ and stir for 20min. Add 0.5g of aminothiourea, 2g of dodecyl primary amine and 1g of 2,2'-dithiodiethylamine. Stir and react at 80℃ for 4h. After the reaction is complete, filter, wash the filter cake with distilled water until the washing liquid is neutral, and finally vacuum dry at 60℃ to constant weight to obtain modified lignin.

[0048] Preparation Example 2 A modified lignin is prepared by the following steps: S1. Add 1g of 3-chloropropyltriethoxysilane to 15mL of 80wt% ethanol solution, stir well, adjust the pH to 4 with acetic acid, and continue stirring for 2h to obtain hydrolysate; put 100g of alkali lignin powder into a mixer, stir at 1000r / min while spraying the hydrolysate onto the lignin surface, continue mixing for 8min after spraying, and dry at 105℃ for 2h to obtain chlorinated lignin; S2. Add 10g of chlorinated lignin to 100mL of N,N-dimethylformamide, stir well, and adjust the pH to 9 with 8wt% sodium hydroxide solution. Heat to 65℃ and stir for 20min. Add 1.0g of aminothiourea, 3g of tetradecylamine and 1.5g of 2,2'-dithiodiethylamine. Stir and react at 83℃ for 5h. After the reaction is complete, filter, wash the filter cake with distilled water until the washing liquid is neutral, and finally vacuum dry at 60℃ to constant weight to obtain modified lignin.

[0049] Preparation Example 3 A modified lignin is prepared by the following steps: S1. Add 2g of 3-chloropropyltrimethoxysilane to 20mL of 90wt% ethanol solution, stir well, adjust the pH to 5 with acetic acid, and continue stirring for 2h to obtain hydrolysate; put 100g of alkali lignin powder into a mixer, stir at 1500r / min while spraying the hydrolysate onto the lignin surface, continue mixing for 10min after spraying, and dry at 105℃ for 2h to obtain chlorinated lignin; S2. Add 10g of chlorinated lignin to 100mL of N,N-dimethylformamide, stir well, and adjust the pH to 10 with 10wt% sodium hydroxide solution. Heat to 70℃ and stir for 20min. Add 1.5g of aminothiourea, 5g of octadecylamine and 2g of 2,2'-dithiodiethylamine. Stir and react at 85℃ for 6h. After the reaction is complete, filter, wash the filter cake with distilled water until the washing liquid is neutral, and finally vacuum dry at 60℃ to constant weight to obtain modified lignin.

[0050] Compare with Example 1 A modified lignin, which differs from Preparation Example 2 only in that all aminothiourea and 2,2'-dithiodiethylamine in Preparation Example 2 are replaced with an equal mass of tetradecylamine.

[0051] Compare with Example 2 A modified lignin, which differs from Preparation Example 2 only in that all aminothiourea and tetradecylamine in Preparation Example 2 are replaced with an equal mass of 2,2'-dithiodiethylamine.

[0052] Compare with Example 3 A modified lignin, which differs from Preparation Example 2 only in that all 2,2'-dithiodiethylamine and tetradecylamine in Preparation Example 2 are replaced with an equal mass of aminothiourea.

[0053] Compare with Example 4 A modified lignin, compared with Preparation Example 2, differs only in that "1.0g aminothiourea, 3g tetradecylamine and 1.5g 2,2'-dithiodiethylamine" in Preparation Example 2 is adjusted to "3.5g tetradecylamine and 2g 2,2'-dithiodiethylamine".

[0054] Compare with Example 5 A modified lignin, compared with Preparation Example 2, differs only in that "1.0g aminothiourea, 3g tetradecylamine and 1.5g 2,2'-dithiodiethylamine" in Preparation Example 2 is adjusted to "2.5g aminothiourea and 3g 2,2'-dithiodiethylamine".

[0055] Compare with Example 6 A modified lignin, compared with Preparation Example 2, differs only in that "1.0g aminothiourea, 3g tetradecylamine and 1.5g 2,2'-dithiodiethylamine" in Preparation Example 2 is adjusted to "1.75g ​​aminothiourea and 3.75g tetradecylamine".

[0056] Compare with Example 7 This comparative example is chlorinated lignin, and the preparation process of chlorinated lignin is the same as that in Preparation Example 2.

[0057] Example 1 A weather-resistant and anti-aging masterbatch for PE drainage pipes, comprising the following raw materials by weight: 50 parts of carrier resin, 20 parts of supported weather-resistant component, 5 parts of modified lignin from Preparation Example 1, 3 parts of maleic anhydride-grafted polyethylene, and 2 parts of calcium stearate.

[0058] The preparation steps of the supported weather-resistant component are as follows: 1g of antioxidant 1010, 0.5g of UV absorber UV-531 and 0.5g of light stabilizer 944 were added to 30mL of acetone and mixed evenly. Then 4g of SBA-15 was added, and the mixture was ultrasonically treated at 50℃ for 0.5h with a power of 150W and a frequency of 35kHz. Finally, the acetone was removed by drying to obtain the supported weather-resistant component.

[0059] The carrier resin is a mixture of low-density polyethylene and linear low-density polyethylene in a mass ratio of 1:1. The melt index of the low-density polyethylene is 5 g / 10 min (190℃ / 2.16 kg), and the melt index of the linear low-density polyethylene is 20 g / 10 min (190℃ / 2.16 kg).

[0060] The preparation method of the weather-resistant and anti-aging masterbatch for PE drainage pipes described above includes the following steps: The carrier resin, loaded weather-resistant component, modified lignin, maleic anhydride grafted polyethylene, and calcium stearate were added to a mixer and mixed for 10 minutes. Then, the mixture was transferred to a twin-screw extruder. The temperature of the twin-screw extruder was 170℃ in zone 1, 175℃ in zone 2, 180℃ in zone 3, 180℃ in zone 4, and 170℃ in zone 5. The mixture was then extruded and granulated to obtain a weather-resistant and anti-aging masterbatch for PE drainage pipes.

[0061] Example 2 A weather-resistant and anti-aging masterbatch for PE drainage pipes, comprising the following raw materials by weight: 55 parts of carrier resin, 23 parts of supported weather-resistant component, 8 parts of modified lignin from Preparation Example 1, 4 parts of maleic anhydride-grafted polyethylene, and 3 parts of calcium stearate.

[0062] The preparation processes for the supported weather-resistant components, carrier resin, and masterbatch are the same as in Example 1.

[0063] Example 3 A weather-resistant and anti-aging masterbatch for PE drainage pipes, comprising the following raw materials by weight: The mixture contained 60 parts of carrier resin, 25 parts of supported weather-resistant component, 10 parts of modified lignin from Preparation Example 1, 6 parts of maleic anhydride-grafted polyethylene, and 4 parts of calcium stearate.

[0064] The preparation processes for the supported weather-resistant components, carrier resin, and masterbatch are the same as in Example 1.

[0065] Example 4 A weather-resistant and anti-aging masterbatch for PE drainage pipes, which differs from Example 1 only in that the modified lignin in Example 1 is replaced with an equal weight of the product obtained in Preparation Example 2.

[0066] Example 5 A weather-resistant and anti-aging masterbatch for PE drainage pipes, which differs from Example 1 only in that the modified lignin in Example 1 is replaced with an equal weight of the product obtained in Preparation Example 3.

[0067] Example 6 A weather-resistant and anti-aging masterbatch for PE drainage pipes, which differs from Example 2 only in that the modified lignin in Example 2 is replaced with an equal weight of the product obtained in Preparation Example 2.

[0068] Example 7 A weather-resistant and anti-aging masterbatch for PE drainage pipes differs from Example 1 only in that the preparation steps of the supported weather-resistant component in this example are as follows: Add 1.5g of antioxidant 1010, 0.5g of UV absorber UV-531 and 0.5g of light stabilizer 944 to 50mL of acetone and mix well. Then add 5g of SBA-15, and sonicate at 50℃ for 0.5h with a power of 150W and a frequency of 35kHz. Finally, dry to remove acetone to obtain the supported weather-resistant component.

[0069] Example 8 A weather-resistant and anti-aging masterbatch for PE drainage pipes differs from Example 1 only in that the preparation steps of the supported weather-resistant component in this example are as follows: Add 2g of antioxidant 1010, 1g of UV absorber UV-531 and 1g of light stabilizer 944 to 80mL of acetone and mix well. Then add 2g of SBA-15, and sonicate at 60℃ for 1h with a power of 200W and a frequency of 35-45kHz. Finally, dry to remove acetone to obtain the supported weather-resistant component.

[0070] Comparative Example 1 A weather-resistant and anti-aging masterbatch for PE drainage pipes, which differs from Example 4 only in that the modified lignin in Example 4 is replaced with an equal part by weight of the product obtained from Comparative Example 1.

[0071] Comparative Example 2 A weather-resistant and anti-aging masterbatch for PE drainage pipes, which differs from Example 4 only in that the modified lignin in Example 4 is replaced with an equal part by weight of the product obtained from Comparative Example 2.

[0072] Comparative Example 3 A weather-resistant and anti-aging masterbatch for PE drainage pipes, which differs from Example 4 only in that the modified lignin in Example 4 is replaced with an equal part by weight of the product obtained from Comparative Example 3.

[0073] Comparative Example 4 A weather-resistant and anti-aging masterbatch for PE drainage pipes, which differs from Example 4 only in that the modified lignin in Example 4 is replaced with an equal weight of the product obtained in Comparative Example 4.

[0074] Comparative Example 5 A weather-resistant and anti-aging masterbatch for PE drainage pipes, which differs from Example 4 only in that the modified lignin in Example 4 is replaced with an equal weight of the product obtained from Comparative Example 5.

[0075] Comparative Example 6 A weather-resistant and anti-aging masterbatch for PE drainage pipes, which differs from Example 4 only in that the modified lignin in Example 4 is replaced with an equal weight of the product obtained from Comparative Example 6.

[0076] Comparative Example 7 A weather-resistant and anti-aging masterbatch for PE drainage pipes, which differs from Example 4 only in that the modified lignin in Example 4 is replaced with an equal part by weight of the product obtained in Comparative Example 7.

[0077] The weather-resistant and anti-aging masterbatches prepared in Examples 1-8 and Comparative Examples 1-7 were mixed with recycled high-density polyethylene at a mass ratio of 4:96. The mixture was then transferred to a twin-screw extruder. The temperatures in the first zone of the twin-screw extruder were 170°C, the second zone 175°C, the third zone 180°C, the fourth zone 180°C, and the fifth zone 170°C. The mixture was extruded and granulated to obtain composite granules. These granules were then preheated at 190°C for 3 minutes, hot-pressed for 5 minutes, and cold-pressed for 2 minutes in a flat vulcanizing press to form 1mm thick samples. Standard-sized samples were then cut and tested. The test items are as follows: Mechanical properties: Tensile strength and elongation at break were tested according to GB / T1040.2-2022, with a tensile speed of 50 mm / min; Oxidation induction period at 200℃: The test was conducted according to GB / T19466.6-2009, with an oxygen atmosphere of 50 mL / min; Weather resistance: Accelerated aging test was conducted according to GB / T16422.2-2022, with xenon lamp aging for 500 hours. The change rate of tensile strength was tested. Tensile strength change rate = (tensile strength before aging - tensile strength after aging) / tensile strength before aging × 100%; The test results are shown in Table 1: Table 1

[0078] As can be seen from the test results in Table 1, compared with Comparative Examples 1-7, the composite materials prepared in Examples 1-8 have both good mechanical properties and weather resistance. This indicates that the free radical scavenging effect of the aminothiourea group in the modified lignin of the present invention and the slow-release antioxidant effect of the supported weather-resistant component have produced a significant synergistic effect, which greatly improves the thermo-oxidative stability of the material.

[0079] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A weather-resistant and anti-aging masterbatch for PE drainage pipes, characterized in that, By weight, it includes the following ingredients: 50-60 parts carrier resin, 20-25 parts supported weather-resistant component, 5-10 parts modified lignin, 3-6 parts compatibilizer, and 2-4 parts lubricant; The supported weather-resistant component is a mesoporous silica-supported weather-resistant additive; The modified lignin carries long-chain alkyl groups, aminothiourea groups, and disulfide bonds.

2. The weather-resistant and anti-aging masterbatch for PE drainage pipes according to claim 1, characterized in that, The mass ratio of mesoporous silica to weather-resistant additives is 1:0.5-2. The weather-resistant additives include antioxidants, ultraviolet absorbers, and light stabilizers, and the mass ratio of antioxidants, ultraviolet absorbers, and light stabilizers is 1-2:0.5-1:0.5-1.

3. The weather-resistant and anti-aging masterbatch for PE drainage pipes according to claim 1, characterized in that, The preparation steps of the supported weather-resistant component are as follows: Antioxidants, UV absorbers, and light stabilizers are added to acetone and mixed thoroughly. Then, mesoporous silica is added, and the mixture is ultrasonically treated. Finally, the acetone is removed by drying to obtain the supported weather-resistant component.

4. The weather-resistant and anti-aging masterbatch for PE drainage pipes according to claim 1, characterized in that, The modified lignin is the product of alkali lignin undergoing coupling chlorination with chlorosiloxane, followed by nucleophilic substitution reaction with aminothiourea, long-chain alkylamine and 2,2'-dithiodiethylamine.

5. The weather-resistant and anti-aging masterbatch for PE drainage pipes according to claim 4, characterized in that, The chlorosiloxane is at least one of 3-chloropropylmethyldiethoxysilane, 3-chloropropyltriethoxysilane, and 3-chloropropyltrimethoxysilane, and the long-chain alkylamine is at least one of dodecyl primary amine, tetradecylamine, hexadecylamine, and octadecylamine.

6. A weather-resistant and anti-aging masterbatch for PE drainage pipes according to claim 1 or 4, characterized in that, The modified lignin preparation steps are as follows: S1. Add chlorosiloxane to an ethanol solution, stir evenly, adjust the pH to 4-5 with acetic acid, and continue stirring for 2 hours to obtain a hydrolysate; load alkali lignin powder into a mixer, and spray the hydrolysate onto the lignin surface while stirring, controlling the rotation speed to 500-1500 r / min. After spraying, continue mixing for 5-10 min, and dry at 105℃ for 2 hours to obtain chlorinated lignin. S2. Add chlorinated lignin to N,N-dimethylformamide, stir evenly, and adjust the pH to 9-10 with sodium hydroxide solution. Heat to 60-70℃ and stir for 20 min. Add aminothiourea, long-chain alkylamine and 2,2'-dithiodiethylamine. Stir and react at 80-85℃ for 4-6 h. After the reaction is complete, filter, wash the filter cake with distilled water until the washing liquid is neutral, and finally vacuum dry at 60℃ to constant weight to obtain modified lignin.

7. The weather-resistant and anti-aging masterbatch for PE drainage pipes according to claim 6, characterized in that, The amount of chlorosiloxane used in S1 is 0.5-2% of the mass of alkali lignin powder.

8. The weather-resistant and anti-aging masterbatch for PE drainage pipes according to claim 6, characterized in that, In S2, the mass ratio of chlorinated lignin, aminothiourea, long-chain alkylamine and 2,2'-dithiodiethylamine is 10:0.5-1.5:2-5:1-2, and the mass fraction of sodium hydroxide solution is 5-10%.

9. A method for preparing weather-resistant and anti-aging masterbatch for PE drainage pipes, used to prepare the weather-resistant and anti-aging masterbatch for PE drainage pipes as described in any one of claims 1-8, characterized in that, Includes the following steps: The carrier resin, loaded weather-resistant component, modified lignin, compatibilizer, and lubricant are added to a mixer and mixed for 10-20 minutes. Then, the mixture is transferred to a twin-screw extruder and extruded and granulated to obtain a weather-resistant and anti-aging masterbatch for PE drainage pipes.

10. The application of the weather-resistant and anti-aging masterbatch for PE drainage pipes as described in any one of claims 1-8 in the preparation of drainage pipes made primarily of recycled polyethylene.

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