Modified recycled polyethylene geomembrane and method for preparing the same

Abstract

This invention relates to the field of geomembrane material technology, specifically to a modified recycled polyethylene geomembrane and its preparation method. It addresses the problem that existing recycled polyethylene geomembranes are prone to aging and erosion under prolonged sunlight, oxidation, and acid / alkali environments, leading to a significant decline in performance and affecting their service life. This preparation method uses recycled polyethylene resin as the main raw material to prepare the geomembrane, achieving resource recycling and demonstrating significant economic and environmental benefits. Adding multi-effect light stabilizers and composite light absorbers significantly improves the mechanical properties of the geomembrane, as well as its aging resistance and acid / alkali resistance, making it suitable for various applications requiring seepage prevention, isolation, and reinforcement, such as water conservancy, transportation, and construction. Furthermore, it significantly extends the service life of the geomembrane, reduces replacement frequency, and further embodies the concept of environmental protection and energy conservation.

Description

Technical Field

[0001] This invention relates to the field of geomembrane materials technology, specifically to a modified recycled polyethylene geomembrane and its preparation method. Background Technology

[0002] Geomembranes are widely used in many engineering fields, such as construction, transportation, and environmental engineering, due to their excellent waterproofing and seepage prevention functions. Traditionally, geomembranes are mainly made of polyethylene or polypropylene, which have good weather resistance and mechanical strength. However, with increasing environmental awareness, the recycling of waste polyethylene materials has become a focus. Because polyethylene materials have similar polymer structures, they can be partially recycled through physical or chemical methods, thereby extending the lifespan of resources and reducing environmental pollution. Nevertheless, geomembranes made directly from recycled polyethylene materials still face many challenges during use. They are prone to aging and erosion under prolonged exposure to sunlight, oxidation, and acidic or alkaline environments, leading to a significant decline in performance and affecting their service life.

[0003] Therefore, developing a modified recycled polyethylene geomembrane and its preparation method is of great significance. Summary of the Invention

[0004] In order to overcome the above-mentioned technical problems, the present invention aims to provide a modified recycled polyethylene geomembrane and its preparation method, which solves the problem that existing recycled polyethylene geomembranes are prone to aging and erosion under long-term exposure to sunlight, oxidation and acid and alkaline environments, resulting in a significant decline in their performance and affecting their service life.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A modified recycled polyethylene geomembrane comprises the following components in parts by weight:

[0007] 100 parts recycled polyethylene resin, 0.5-3.5 parts multi-effect light stabilizer, 2-6 parts composite light absorber, 1-3 parts plasticizer, 3-5 parts lubricant, and 0.5-1.5 parts compatibilizer;

[0008] The multi-effect light stabilizer is prepared by the following steps:

[0009] Step A1: Heptafluorobutyric acid and N,N-dimethylformamide were added to a three-necked flask equipped with a stirrer, thermometer, and constant pressure dropping funnel. The mixture was stirred for 10-20 min at a temperature of 25-30℃ and a stirring rate of 250-300 r / min. Then, thionyl chloride was added dropwise while stirring, with the dropping rate controlled at 1-2 drops / s. After the addition was completed, the mixture was stirred for another 20-30 min. Then, the temperature was raised to 80-85℃ and the mixture was stirred for another 2-3 h. After the reaction was completed, the reaction product was cooled to room temperature and then distilled at atmospheric pressure. The fraction at 39℃ was collected to obtain the fluorinated acyl chloride intermediate.

[0010] Step A2: Add 2,2,6,6-tetramethylpiperidinamine, triethylamine, and dichloromethane to a three-necked flask equipped with a stirrer, thermometer, and constant-pressure dropping funnel. Stir the reaction at 0-5℃ and a stirring rate of 250-300 r / min for 10-20 min. Then, while stirring, add the fluorinated acyl chloride intermediate-dichloromethane solution dropwise at a rate of 1-2 drops / s. After the addition is complete, raise the temperature to 40-45℃ and continue stirring for 2-3 h. After the reaction is complete, cool the reaction product to room temperature, then remove the solvent by rotary evaporation. Wash the product 2-3 times with distilled water, and then recrystallize it with anhydrous acetone to obtain the multi-effect light stabilizer.

[0011] As a further aspect of the present invention: the ratio of heptafluorobutyric acid, N,N-dimethylformamide and thionyl chloride used in step A1 is 10 mmol: 0.05-0.1 g: 20 mmol.

[0012] As a further aspect of the present invention: the ratio of the amount of 2,2,6,6-tetramethylpiperidineamine, triethylamine, dichloromethane and the fluorinated acyl chloride intermediate-dichloromethane solution in step A2 is 10 mmol: 11-12 mmol: 30-40 mL: 20-25 mL.

[0013] As a further aspect of the present invention: the fluorinated acyl chloride intermediate-dichloromethane solution in step A2 is a solution formed by dissolving the fluorinated acyl chloride intermediate in dichloromethane at a ratio of 11-13 mmol / L: 20 mL.

[0014] As a further aspect of the present invention: the composite light absorber is prepared by the following steps:

[0015] Step B1: Add titanium oxysulfate, zinc chloride, and deionized water to a three-necked flask equipped with a stirrer, thermometer, and constant pressure dropping funnel. Stir the reaction for 20-30 minutes at a temperature of 25-30℃ and a stirring rate of 250-300 r / min. Then add a dispersant and continue stirring for 3-5 minutes. Then add ammonia water dropwise while stirring, controlling the dropping rate to 1-2 drops / s, until the pH reaches 7. Continue stirring for 40-60 minutes. After centrifugation, wash the precipitate 2-3 times with anhydrous ethanol and distilled water. Then place it in a vacuum drying oven and dry it for 8-10 hours at a temperature of 65-70℃. Then place it in a muffle furnace and calcine it for 4-5 hours at a temperature of 680-720℃. Then cool it with the furnace to obtain titanium-zinc composite powder.

[0016] Step B2: Add tris(hydroxymethyl)aminomethane and hydrochloric acid solution to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Stir the mixture at 25-30℃ and a stirring rate of 250-300 r / min for 3-5 min. Then adjust the pH to 8.5 with deionized water. Add titanium-zinc composite powder and ultrasonically disperse it at 25-30℃ and an ultrasonic frequency of 30-40 kHz for 20-30 min. Add dopamine and stir the mixture at 25-30℃ and a stirring rate of 250-300 r / min for 1-2 h. Then raise the temperature to 40-45℃ and continue stirring for 20-30 h. After the reaction is complete, cool the reaction product to room temperature, centrifuge it, and place the precipitate in a vacuum drying oven to dry it at 60-65℃ for 8-10 h to obtain the composite light absorber.

[0017] As a further aspect of the present invention: the ratio of titanium oxysulfate, zinc chloride, deionized water and dispersant in step B1 is 10 mmol: 10 mmol: 30-35 mL: 0.04-0.08 g.

[0018] As a further aspect of the present invention: the dispersant in step B1 is polyethylene glycol.

[0019] As a further aspect of the present invention: the polyethylene glycol in step B1 is one of PEG200, PEG400 and PEG600.

[0020] As a further aspect of the present invention: the mass fraction of the ammonia water in step B1 is 20-25%.

[0021] As a further aspect of the present invention: the ratio of the amount of tris(hydroxymethyl)aminomethane, hydrochloric acid solution, titanium-zinc composite powder and dopamine in step B2 is 1.6g:30mL:1-2g:1.5-3.5g.

[0022] As a further aspect of the present invention: the molar concentration of the hydrochloric acid solution in step B2 is 0.1 mol / L.

[0023] As a further aspect of the present invention: a method for preparing a modified recycled polyethylene geomembrane, comprising the following steps:

[0024] Step 1: Weigh out 100 parts of recycled polyethylene resin, 0.5-3.5 parts of multi-effect light stabilizer, 2-6 parts of composite light absorber, 1-3 parts of plasticizer, 3-5 parts of lubricant, and 0.5-1.5 parts of compatibilizer according to the following weight proportions, and set aside for later use;

[0025] Step 2: Add the recycled polyethylene resin, multi-effect light stabilizer, composite light absorber, plasticizer, lubricant and compatibilizer into the mixer, and stir and mix for 15-25 minutes at a temperature of 50-60℃ and a stirring speed of 600-800r / min to obtain the premix.

[0026] Step 3: Add the premixed material to a twin-screw extruder and melt-extrude it at a temperature of 170-180℃ and a screw speed of 50-100r / min. Then, calender it to obtain a modified recycled polyethylene geomembrane.

[0027] As a further aspect of the present invention: the recycled polyethylene resin is Zhongxin Yihua recycled PE granules with a specific gravity of 0.95 g / cm³. 3 Its melting point is 120℃.

[0028] As a further aspect of the present invention: the plasticizer is one of dimethyl phthalate, dibutyl phthalate, and dioctyl phthalate.

[0029] As a further aspect of the present invention: the compatibilizer is one of PE-g-ST and PE-g-MAH.

[0030] As a further aspect of the present invention, the lubricant is one of stearic acid, butyl stearate, and polyethylene wax.

[0031] The beneficial effects of this invention are:

[0032] This invention discloses a modified recycled polyethylene geomembrane and its preparation method. The method involves adding recycled polyethylene resin, a multi-effect light stabilizer, a composite light absorber, a plasticizer, a lubricant, and a compatibilizer to a mixer and mixing them to obtain a premix. The premix is ​​then melt-extruded in a twin-screw extruder and subsequently calendered to obtain the modified recycled polyethylene geomembrane. This preparation method uses recycled polyethylene resin as the main raw material to prepare the geomembrane, achieving resource recycling, reducing production costs, and minimizing environmental pollution. It is green and environmentally friendly, offering significant economic and environmental benefits. The addition of the multi-effect light stabilizer and composite light absorber significantly improves the mechanical properties of the geomembrane, as well as its aging resistance and acid and alkali resistance, making it suitable for various applications requiring seepage prevention, isolation, and reinforcement, such as water conservancy, transportation, and construction. Furthermore, it significantly extends the service life of the geomembrane, reduces replacement frequency, and further embodies the concept of environmental protection and energy conservation.

[0033] In the preparation of modified recycled polyethylene geomembrane, a multi-functional light stabilizer was first prepared. Heptafluorobutyric acid (HFA) was acyl-chlorinated using a reaction with thionyl chloride, converting the carboxyl group into an acyl chloride group to obtain a fluorinated acyl chloride intermediate. Subsequently, 2,2,6,6-tetramethylpiperidinamine and the fluorinated acyl chloride intermediate reacted, with the acyl chloride group on the fluorinated acyl chloride intermediate reacting with the amino group on 2,2,6,6-tetramethylpiperidinamine to form a multi-functional light stabilizer containing numerous CF bonds and hindered amine structures. Recycled polyethylene is susceptible to photo-oxidative excitation, generating free radicals. These free radicals further initiate chain degradation reactions, leading to the degradation of recycled polyethylene. The performance of polyethylene materials deteriorates, while the hindered amine structure in multi-effect light stabilizers has excellent free radical scavenging ability. It can quickly combine with these free radicals, thereby blocking the chain degradation reaction and protecting the recycled polyethylene molecular chain from damage. Fluorine has extremely high electronegativity and can be tightly adsorbed around the recycled polyethylene molecular chain to form a dense protective layer. This protective layer can not only effectively block the damage of photo-oxidation, thereby effectively reducing the possibility of photo-oxidation degradation, but also endow it with excellent hydrophobic properties, making it less susceptible to corrosion by acid and alkali media, and giving it excellent acid and alkali resistance, thus significantly extending the stability of recycled polyethylene materials.

[0034] In the process of preparing modified recycled polyethylene geomembrane, a composite light absorber was also prepared. Titanium dioxide and zinc oxide composite nanoparticles were prepared using titanium oxysulfate and zinc chloride as raw materials to obtain titanium-zinc composite powder. Then, dopamine was self-polymerized with the titanium-zinc composite powder under alkaline conditions to form a polydopamine coating layer, thus obtaining the composite light absorber. Titanium dioxide and zinc oxide are both excellent ultraviolet absorbing materials. They can absorb and convert ultraviolet rays into harmless heat energy. The synergistic effect of the two significantly improves the ability of recycled polyethylene material to block light damage and also improves its mechanical properties. Polydopamine has extremely strong adhesion and dispersibility. After coating the titanium-zinc composite powder with polydopamine, not only is the dispersibility of the titanium-zinc composite powder improved, but the interfacial interaction between it and polyethylene resin is also enhanced, so that the nanoparticles can be more uniformly dispersed in the recycled polyethylene material matrix. Moreover, polydopamine itself also has broad-spectrum light absorption characteristics, further improving the ultraviolet absorption effect of titanium-zinc composite powder. Detailed Implementation

[0035] 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.

[0036] Example 1:

[0037] This embodiment describes a method for preparing a modified recycled polyethylene geomembrane, comprising the following steps:

[0038] Step S1: 10 mmol of heptafluorobutyric acid and 0.05 g of N,N-dimethylformamide were added to a three-necked flask equipped with a stirrer, thermometer and constant pressure dropping funnel. The mixture was stirred for 10 min at 25 °C and a stirring rate of 250 r / min. Then, 20 mmol of thionyl chloride was added dropwise while stirring, with the dropping rate controlled at 1 drop / s. After the addition was completed, the mixture was stirred for another 20 min. Then, the mixture was heated to 80 °C and stirred for another 2 h. After the reaction was completed, the reaction product was cooled to room temperature and then distilled at atmospheric pressure. The fraction at 39 °C was collected to obtain the fluorinated acyl chloride intermediate.

[0039] Step S2: 10 mmol of 2,2,6,6-tetramethylpiperidinamine, 11 mmol of triethylamine, and 30 mL of dichloromethane were added to a three-necked flask equipped with a stirrer, thermometer, and constant pressure dropping funnel. The mixture was stirred at 0 °C and a stirring rate of 250 r / min for 10 min. Then, while stirring, 20 mL of a fluorinated acyl chloride intermediate-dichloromethane solution was added dropwise. The fluorinated acyl chloride intermediate was dissolved in dichloromethane at a ratio of 11 mmol: 20 mL, and the dropping rate was controlled at 1 drop / s. After the addition was completed, the temperature was raised to 40 °C and the reaction was stirred for 2 h. After the reaction was completed, the reaction product was cooled to room temperature, and the solvent was removed by rotary evaporation. The product was then washed twice with distilled water and recrystallized with anhydrous acetone to obtain the multi-effect light stabilizer.

[0040] Step S3: Add 10 mmol of titanium oxysulfate, 10 mmol of zinc chloride, and 30 mL of deionized water to a three-necked flask equipped with a stirrer, thermometer, and constant pressure dropping funnel. Stir the mixture at 25°C and a stirring rate of 250 r / min for 20 min. Then add 0.04 g of PEG200 dispersant and continue stirring for 3 min. Then add 20% ammonia water dropwise while stirring, controlling the dropping rate to 1 drop / s, until the pH reaches 7. Continue stirring for 40 min. After centrifugation, wash the precipitate twice with anhydrous ethanol and distilled water, then place it in a vacuum drying oven and dry it at 65°C for 8 h. Then place it in a muffle furnace and calcine it at 680°C for 4 h. After cooling in the furnace, titanium-zinc composite powder is obtained.

[0041] Step S4: Add 1.6g of tris(hydroxymethyl)aminomethane and 30mL of 0.1mol / L hydrochloric acid solution to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Stir the mixture at 25℃ and 250r / min for 3min. Then adjust the pH to 8.5 with deionized water. Add 1g of titanium-zinc composite powder and ultrasonically disperse it at 25℃ and 30kHz for 20min. Add 1.5g of dopamine and stir the mixture at 25℃ and 250r / min for 1h. Then raise the temperature to 40℃ and continue stirring for 20h. After the reaction is complete, cool the reaction product to room temperature, centrifuge it, and place the precipitate in a vacuum drying oven to dry at 60℃ for 8h to obtain the composite light absorber.

[0042] Step S5: Weigh out 100 parts by weight of recycled polyethylene resin, 0.5 parts by weight of multi-effect light stabilizer, 2 parts by weight of composite light absorber, 1 part by weight of plasticizer, 3 parts by weight of lubricant, and 0.5 parts by weight of compatibilizer, and set aside; the recycled polyethylene resin is Zhongxin Yihua recycled PE granules with a specific gravity of 0.95 g / cm³. 3 The melting point is 120℃; the plasticizer is dimethyl phthalate; the compatibilizer is PE-g-ST; the lubricant is stearic acid;

[0043] Step S6: Add recycled polyethylene resin, multi-effect light stabilizer, composite light absorber, plasticizer, lubricant and compatibilizer to a mixer, and mix for 15 minutes at a temperature of 50°C and a stirring speed of 600 r / min to obtain a premix.

[0044] Step S7: Add the premix to a twin-screw extruder and melt-extrude it at a temperature of 170°C and a screw speed of 50 r / min. Then, calender it to obtain a modified recycled polyethylene geomembrane.

[0045] Example 2:

[0046] This embodiment describes a method for preparing a modified recycled polyethylene geomembrane, comprising the following steps:

[0047] Step S1: 10 mmol of heptafluorobutyric acid and 0.08 g of N,N-dimethylformamide were added to a three-necked flask equipped with a stirrer, thermometer and constant pressure dropping funnel. The mixture was stirred for 15 min at 28 °C and a stirring rate of 275 r / min. Then, 20 mmol of thionyl chloride was added dropwise while stirring, with the dropping rate controlled at 1 drop / s. After the addition was completed, the mixture was stirred for another 25 min. Then, the mixture was heated to 82 °C and stirred for another 2.5 h. After the reaction was completed, the reaction product was cooled to room temperature and then distilled at atmospheric pressure. The fraction at 39 °C was collected to obtain the fluorinated acyl chloride intermediate.

[0048] Step S2: 10 mmol of 2,2,6,6-tetramethylpiperidinamine, 11.5 mmol of triethylamine, and 35 mL of dichloromethane were added to a three-necked flask equipped with a stirrer, thermometer, and constant pressure dropping funnel. The mixture was stirred at 3 °C and a stirring rate of 275 r / min for 15 min. Then, while stirring, 22 mL of a fluorinated acyl chloride intermediate-dichloromethane solution was added dropwise. The fluorinated acyl chloride intermediate was dissolved in dichloromethane at a ratio of 12 mmol: 20 mL, and the dropping rate was controlled at 1 drop / s. After the addition was completed, the temperature was raised to 42 °C and the reaction was stirred for 2.5 h. After the reaction was completed, the reaction product was cooled to room temperature, and the solvent was removed by rotary evaporation. The product was then washed twice with distilled water and recrystallized with anhydrous acetone to obtain the multi-effect light stabilizer.

[0049] Step S3: Add 10 mmol of titanium oxysulfate, 10 mmol of zinc chloride, and 32 mL of deionized water to a three-necked flask equipped with a stirrer, thermometer, and constant pressure dropping funnel. Stir the mixture at 28°C and a stirring rate of 275 r / min for 25 min. Then add 0.06 g of PEG400 dispersant and continue stirring for 4 min. Then add 22% ammonia water dropwise while stirring, controlling the dropping rate to 1 drop / s, until the pH reaches 7. Continue stirring for 50 min. After centrifugation, wash the precipitate twice with anhydrous ethanol and distilled water, then place it in a vacuum drying oven and dry it at 68°C for 9 h. Then place it in a muffle furnace and calcine it at 700°C for 4.5 h. After cooling in the furnace, titanium-zinc composite powder is obtained.

[0050] Step S4: 1.6 g of tris(hydroxymethyl)aminomethane and 30 mL of 0.1 mol / L hydrochloric acid solution were added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. The mixture was stirred at 28 °C and 275 r / min for 4 min. The pH was then adjusted to 8.5 with deionized water. 1.5 g of titanium-zinc composite powder was added and ultrasonically dispersed at 28 °C and 35 kHz for 25 min. 2.5 g of dopamine was added and the mixture was stirred at 28 °C and 275 r / min for 1.5 h. The mixture was then heated to 42 °C and stirred for another 25 h. After the reaction was completed, the product was cooled to room temperature, centrifuged, and the precipitate was placed in a vacuum drying oven and dried at 62 °C for 9 h to obtain the composite light absorber.

[0051] Step S5: Weigh out 100 parts by weight of recycled polyethylene resin, 2 parts by weight of multi-effect light stabilizer, 4 parts by weight of composite light absorber, 2 parts by weight of plasticizer, 4 parts by weight of lubricant, and 1 part by weight of compatibilizer, and set aside; the recycled polyethylene resin is Zhongxin Yihua recycled PE granules with a specific gravity of 0.95 g / cm³. 3 The melting point is 120℃; the plasticizer is dibutyl phthalate; the compatibilizer is PE-g-ST; the lubricant is butyl stearate;

[0052] Step S6: Add recycled polyethylene resin, multi-effect light stabilizer, composite light absorber, plasticizer, lubricant and compatibilizer to a mixer and mix for 20 minutes at a temperature of 55℃ and a stirring speed of 700r / min to obtain a premix.

[0053] Step S7: Add the premix to a twin-screw extruder and melt-extrude it at a temperature of 175°C and a screw speed of 75 r / min. Then, calender it to obtain a modified recycled polyethylene geomembrane.

[0054] Example 3:

[0055] This embodiment describes a method for preparing a modified recycled polyethylene geomembrane, comprising the following steps:

[0056] Step S1: 10 mmol of heptafluorobutyric acid and 0.1 g of N,N-dimethylformamide were added to a three-necked flask equipped with a stirrer, thermometer and constant pressure dropping funnel. The mixture was stirred at 30 °C and 300 r / min for 20 min. Then, 20 mmol of thionyl chloride was added dropwise while stirring, with the dropping rate controlled at 2 drops / s. After the addition was completed, the mixture was stirred for another 30 min. Then, the mixture was heated to 85 °C and stirred for another 3 h. After the reaction was completed, the reaction product was cooled to room temperature and then distilled at atmospheric pressure. The fraction at 39 °C was collected to obtain the fluorinated acyl chloride intermediate.

[0057] Step S2: 10 mmol of 2,2,6,6-tetramethylpiperidinamine, 12 mmol of triethylamine, and 40 mL of dichloromethane were added to a three-necked flask equipped with a stirrer, thermometer, and constant pressure dropping funnel. The mixture was stirred at 5 °C and a stirring rate of 300 r / min for 20 min. Then, while stirring, 25 mL of a fluorinated acyl chloride intermediate-dichloromethane solution was added dropwise. The fluorinated acyl chloride intermediate was dissolved in dichloromethane at a ratio of 13 mmol: 20 mL, and the dropping rate was controlled at 2 drops / s. After the addition was completed, the temperature was raised to 45 °C and the reaction was stirred for 3 h. After the reaction was completed, the reaction product was cooled to room temperature, and the solvent was removed by rotary evaporation. The product was then washed three times with distilled water and recrystallized with anhydrous acetone to obtain the multi-effect light stabilizer.

[0058] Step S3: Add 10 mmol of titanium oxysulfate, 10 mmol of zinc chloride, and 35 mL of deionized water to a three-necked flask equipped with a stirrer, thermometer, and constant pressure dropping funnel. Stir the mixture at 30°C and 300 r / min for 30 min. Then add 0.08 g of PEG600 dispersant and continue stirring for 5 min. Then add 25% ammonia water dropwise while stirring, controlling the dropping rate to 2 drops / s, until the pH reaches 7. Continue stirring for 60 min. After centrifugation, wash the precipitate three times with anhydrous ethanol and distilled water. Then place it in a vacuum drying oven and dry it at 70°C for 10 h. Then place it in a muffle furnace and calcine it at 720°C for 5 h. After cooling in the furnace, titanium-zinc composite powder is obtained.

[0059] Step S4: Add 1.6g of tris(hydroxymethyl)aminomethane and 30mL of 0.1mol / L hydrochloric acid solution to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Stir the mixture at 30℃ and 300r / min for 5min. Then adjust the pH to 8.5 with deionized water. Add 2g of titanium-zinc composite powder and ultrasonically disperse it at 30℃ and 40kHz for 30min. Add 3.5g of dopamine and stir the mixture at 30℃ and 300r / min for 2h. Then raise the temperature to 45℃ and continue stirring for 30h. After the reaction is complete, cool the reaction product to room temperature, centrifuge it, and place the precipitate in a vacuum drying oven to dry at 65℃ for 10h to obtain the composite light absorber.

[0060] Step S5: Weigh out 100 parts by weight of recycled polyethylene resin, 3.5 parts by weight of multi-effect light stabilizer, 6 parts by weight of composite light absorber, 3 parts by weight of plasticizer, 5 parts by weight of lubricant, and 1.5 parts by weight of compatibilizer, and set aside; the recycled polyethylene resin is Zhongxin Yihua recycled PE granules with a specific gravity of 0.95 g / cm³. 3 The melting point is 120℃; the plasticizer is dioctyl phthalate; the compatibilizer is PE-g-MAH; and the lubricant is polyethylene wax.

[0061] Step S6: Add recycled polyethylene resin, multi-effect light stabilizer, composite light absorber, plasticizer, lubricant and compatibilizer to a mixer and mix for 25 minutes at a temperature of 60℃ and a stirring rate of 800r / min to obtain a premix.

[0062] Step S7: Add the premix to a twin-screw extruder and melt-extrude it at a temperature of 180℃ and a screw speed of 100r / min. Then, calender it to obtain a modified recycled polyethylene geomembrane.

[0063] Comparative Example 1:

[0064] This comparative example illustrates a method for preparing a modified recycled polyethylene geomembrane, comprising the following steps:

[0065] Step S1: Weigh out 100 parts by weight of recycled polyethylene resin, 3 parts by weight of plasticizer, 5 parts by weight of lubricant, and 1.5 parts by weight of compatibilizer, and set aside; the recycled polyethylene resin is Zhongxin Yihua recycled PE granules with a specific gravity of 0.95 g / cm³. 3 The melting point is 120℃; the plasticizer is dioctyl phthalate; the compatibilizer is PE-g-MAH; and the lubricant is polyethylene wax.

[0066] Step S2: Add recycled polyethylene resin, plasticizer, lubricant and compatibilizer to a mixer and mix for 25 minutes at a temperature of 60°C and a stirring rate of 800 r / min to obtain a premix.

[0067] Step S3: Add the premix to a twin-screw extruder and melt-extrude it at a temperature of 180℃ and a screw speed of 100r / min. Then, calender it to obtain a modified recycled polyethylene geomembrane.

[0068] Comparative Example 2:

[0069] This comparative example illustrates a method for preparing a modified recycled polyethylene geomembrane, comprising the following steps:

[0070] Step S1: 10 mmol of heptafluorobutyric acid and 0.1 g of N,N-dimethylformamide were added to a three-necked flask equipped with a stirrer, thermometer and constant pressure dropping funnel. The mixture was stirred at 30 °C and 300 r / min for 20 min. Then, 20 mmol of thionyl chloride was added dropwise while stirring, with the dropping rate controlled at 2 drops / s. After the addition was completed, the mixture was stirred for another 30 min. Then, the mixture was heated to 85 °C and stirred for another 3 h. After the reaction was completed, the reaction product was cooled to room temperature and then distilled at atmospheric pressure. The fraction at 39 °C was collected to obtain the fluorinated acyl chloride intermediate.

[0071] Step S2: 10 mmol of 2,2,6,6-tetramethylpiperidinamine, 12 mmol of triethylamine, and 40 mL of dichloromethane were added to a three-necked flask equipped with a stirrer, thermometer, and constant pressure dropping funnel. The mixture was stirred at 5 °C and a stirring rate of 300 r / min for 20 min. Then, while stirring, 25 mL of a fluorinated acyl chloride intermediate-dichloromethane solution was added dropwise. The fluorinated acyl chloride intermediate was dissolved in dichloromethane at a ratio of 13 mmol: 20 mL, and the dropping rate was controlled at 2 drops / s. After the addition was completed, the temperature was raised to 45 °C and the reaction was stirred for 3 h. After the reaction was completed, the reaction product was cooled to room temperature, and the solvent was removed by rotary evaporation. The product was then washed three times with distilled water and recrystallized with anhydrous acetone to obtain the multi-effect light stabilizer.

[0072] Step S3: Weigh out 100 parts by weight of recycled polyethylene resin, 3.5 parts by weight of multi-effect light stabilizer, 3 parts by weight of plasticizer, 5 parts by weight of lubricant, and 1.5 parts by weight of compatibilizer, and set aside; the recycled polyethylene resin is Zhongxin Yihua recycled PE granules with a specific gravity of 0.95 g / cm³. 3 The melting point is 120℃; the plasticizer is dioctyl phthalate; the compatibilizer is PE-g-MAH; and the lubricant is polyethylene wax.

[0073] Step S4: Add recycled polyethylene resin, multi-effect light stabilizer, plasticizer, lubricant and compatibilizer to a mixer and mix for 25 minutes at a temperature of 60°C and a stirring speed of 800 r / min to obtain a premix.

[0074] Step S5: Add the premix to a twin-screw extruder and melt-extrude it at a temperature of 180℃ and a screw speed of 100r / min. Then, calender it to obtain a modified recycled polyethylene geomembrane.

[0075] Comparative Example 3:

[0076] This comparative example illustrates a method for preparing a modified recycled polyethylene geomembrane, comprising the following steps:

[0077] Step S1: Add 10 mmol of titanium oxysulfate, 10 mmol of zinc chloride, and 35 mL of deionized water to a three-necked flask equipped with a stirrer, thermometer, and constant pressure dropping funnel. Stir the mixture at 30°C and 300 r / min for 30 min. Then add 0.08 g of PEG600 dispersant and continue stirring for 5 min. Then add 25% ammonia water dropwise while stirring, controlling the dropping rate to 2 drops / s, until the pH reaches 7. Continue stirring for 60 min. After centrifugation, wash the precipitate three times with anhydrous ethanol and distilled water. Then place it in a vacuum drying oven and dry it at 70°C for 10 h. Then place it in a muffle furnace and calcine it at 720°C for 5 h. Then cool it with the furnace to obtain titanium-zinc composite powder.

[0078] Step S2: 1.6g of tris(hydroxymethyl)aminomethane and 30mL of 0.1mol / L hydrochloric acid solution were added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. The mixture was stirred at 30℃ and 300r / min for 5min. The pH was then adjusted to 8.5 with deionized water. 2g of titanium-zinc composite powder was added and ultrasonically dispersed at 30℃ and 40kHz for 30min. 3.5g of dopamine was added and the mixture was stirred at 30℃ and 300r / min for 2h. The temperature was then raised to 45℃ and the mixture was stirred for another 30h. After the reaction was completed, the product was cooled to room temperature, centrifuged, and the precipitate was placed in a vacuum drying oven and dried at 65℃ for 10h to obtain the composite light absorber.

[0079] Step S3: Weigh out 100 parts by weight of recycled polyethylene resin, 6 parts by weight of composite light absorber, 3 parts by weight of plasticizer, 5 parts by weight of lubricant, and 1.5 parts by weight of compatibilizer, and set aside; the recycled polyethylene resin is Zhongxin Yihua recycled PE granules with a specific gravity of 0.95 g / cm³.3 The melting point is 120℃; the plasticizer is dioctyl phthalate; the compatibilizer is PE-g-MAH; and the lubricant is polyethylene wax.

[0080] Step S4: Add the recycled polyethylene resin, composite light absorber, plasticizer, lubricant and compatibilizer to the mixer and mix for 25 minutes at a temperature of 60℃ and a stirring speed of 800r / min to obtain the premix.

[0081] Step S5: Add the premix to a twin-screw extruder and melt-extrude it at a temperature of 180℃ and a screw speed of 100r / min. Then, calender it to obtain a modified recycled polyethylene geomembrane.

[0082] Comparative Example 4:

[0083] This comparative example illustrates a method for preparing a modified recycled polyethylene geomembrane, comprising the following steps:

[0084] Step S1: Add 10 mmol of titanium oxysulfate, 10 mmol of zinc chloride, and 35 mL of deionized water to a three-necked flask equipped with a stirrer, thermometer, and constant pressure dropping funnel. Stir the mixture at 30°C and 300 r / min for 30 min. Then add 0.08 g of PEG600 dispersant and continue stirring for 5 min. Then add 25% ammonia water dropwise while stirring, controlling the dropping rate to 2 drops / s, until the pH reaches 7. Continue stirring for 60 min. After centrifugation, wash the precipitate three times with anhydrous ethanol and distilled water. Then place it in a vacuum drying oven and dry it at 70°C for 10 h. Then place it in a muffle furnace and calcine it at 720°C for 5 h. Then cool it with the furnace to obtain titanium-zinc composite powder.

[0085] Step S2: Weigh out 100 parts by weight of recycled polyethylene resin, 3.5 parts by weight of 2,2,6,6-tetramethylpiperidineamine, 6 parts by weight of titanium-zinc composite powder, 3 parts by weight of plasticizer, 5 parts by weight of lubricant, and 1.5 parts by weight of compatibilizer, and set aside; the recycled polyethylene resin is Zhongxin Yihua recycled PE granules with a specific gravity of 0.95 g / cm³. 3 The melting point is 120℃; the plasticizer is dioctyl phthalate; the compatibilizer is PE-g-MAH; and the lubricant is polyethylene wax.

[0086] Step S3: Add recycled polyethylene resin, 2,2,6,6-tetramethylpiperidineamine, titanium zinc composite powder, plasticizer, lubricant and compatibilizer to a mixer and mix for 25 minutes at a temperature of 60℃ and a stirring speed of 800r / min to obtain a premix.

[0087] Step S4: Add the premix to a twin-screw extruder and melt-extrude it at a temperature of 180°C and a screw speed of 100 r / min. Then, calender it to obtain a modified recycled polyethylene geomembrane.

[0088] The modified recycled polyethylene geomembranes of Examples 1-3 and Comparative Examples 1-4 were subjected to performance tests, and the test results are shown in the table below:

[0089]

[0090] Referring to the data in the table above, and based on the comparison between Examples 1-3 and Comparative Examples 1-4, it can be seen that the modified recycled polyethylene geomembrane of this application has excellent mechanical properties, as well as excellent aging resistance and acid and alkali resistance.

[0091] Tensile properties were tested according to ISO 527-2-2012 "Determination of tensile properties of plastics - Part 2: Test conditions for molded and extruded plastics", with a tensile rate of 50 mm / min.

[0092] The change rate of aging performance = (tensile properties after aging - tensile properties before aging) / tensile properties before aging × 100%; where, the aging method is: the sample is placed in a high-temperature aging chamber equipped with ultraviolet lamps and aged for 96 hours at an aging temperature of 80℃ and an ultraviolet light intensity of 75W before testing.

[0093] Change rate of acid resistance = (tensile properties after acid treatment - tensile properties before acid treatment) / tensile properties before acid treatment × 100%; wherein, the acid treatment method is as follows: immerse the sample in a 5% sulfuric acid solution for 100 hours, then take it out, wash it with distilled water until neutral, dry it, and then test it.

[0094] Change rate of alkali resistance = (tensile properties after alkali treatment - tensile properties before alkali treatment) / tensile properties before alkali treatment × 100%; wherein, the alkali treatment method is as follows: immerse the sample in a 10% sodium hydroxide solution for 100 hours, then take it out, wash it with distilled water until neutral, dry it, and then test it.

[0095] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0096] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A modified recycled polyethylene geomembrane, characterized in that, Includes the following components by weight: 100 parts recycled polyethylene resin, 0.5-3.5 parts multi-effect light stabilizer, 2-6 parts composite light absorber, 1-3 parts plasticizer, 3-5 parts lubricant, and 0.5-1.5 parts compatibilizer; The multi-effect light stabilizer is prepared by the following steps: Step A1: Heptafluorobutyric acid and N,N-dimethylformamide were stirred and reacted. Then, thionyl chloride was added dropwise while stirring. After the addition was completed, the reaction was continued to be stirred. After the reaction was completed, the reaction product was cooled and then distilled at atmospheric pressure. The fraction was collected to obtain the fluorinated acyl chloride intermediate. Step A2: 2,2,6,6-Tetramethylpiperidineamine, triethylamine and dichloromethane were stirred and reacted. Then, a solution of dichloromethane containing fluorinated acyl chloride intermediate was added dropwise while stirring. After the addition was complete, the reaction was stirred and reacted. After the reaction was completed, the reaction product was cooled, then rotary evaporated, washed and recrystallized to obtain a multi-effect light stabilizer.

2. The modified recycled polyethylene geomembrane according to claim 1, characterized in that, The ratio of heptafluorobutyric acid, N,N-dimethylformamide and thionyl chloride used in step A1 is 10 mmol: 0.05-0.1 g: 20 mmol.

3. The modified recycled polyethylene geomembrane according to claim 1, characterized in that, In step A2, the ratio of 2,2,6,6-tetramethylpiperidineamine, triethylamine, dichloromethane, and the fluorinated acyl chloride intermediate-dichloromethane solution is 10 mmol: 11-12 mmol: 30-40 mL: 20-25 mL; the fluorinated acyl chloride intermediate-dichloromethane solution is a solution formed by dissolving the fluorinated acyl chloride intermediate in dichloromethane at a ratio of 11-13 mmol: 20 mL.

4. The modified recycled polyethylene geomembrane according to claim 1, characterized in that, The composite light absorber is prepared by the following steps: Step B1: Titanium oxysulfate, zinc chloride and deionized water are stirred and reacted. Then a dispersant is added and the reaction is continued. Then the pH is adjusted with ammonia water and the reaction is continued. Then the mixture is centrifuged, the precipitate is washed, dried and calcined, and then cooled to obtain titanium-zinc composite powder. Step B2: Tris(hydroxymethyl)aminomethane and hydrochloric acid solution are stirred and reacted. Then, the pH is adjusted with deionized water, titanium-zinc composite powder is added and ultrasonically dispersed, followed by the addition of dopamine and stirring. After the reaction is completed, the reaction product is cooled, centrifuged, and the precipitate is dried to obtain the composite light absorber.

5. A modified recycled polyethylene geomembrane according to claim 4, characterized in that, In step B1, the ratio of titanium oxysulfate, zinc chloride, deionized water, and dispersant is 10 mmol: 10 mmol: 30-35 mL: 0.04-0.08 g; the dispersant is polyethylene glycol; the polyethylene glycol is one of PEG200, PEG400, and PEG600; and the mass fraction of ammonia is 20-25%.

6. A modified recycled polyethylene geomembrane according to claim 4, characterized in that, In step B2, the ratio of tris(hydroxymethyl)aminomethane, hydrochloric acid solution, titanium-zinc composite powder, and dopamine is 1.6g:30mL:1-2g:1.5-3.5g; the molar concentration of the hydrochloric acid solution is 0.1mol / L.

7. A method for preparing a modified recycled polyethylene geomembrane as described in any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Weigh out 100 parts of recycled polyethylene resin, 0.5-3.5 parts of multi-effect light stabilizer, 2-6 parts of composite light absorber, 1-3 parts of plasticizer, 3-5 parts of lubricant, and 0.5-1.5 parts of compatibilizer according to the following weight proportions, and set aside for later use; Step 2: Add the recycled polyethylene resin, multi-effect light stabilizer, composite light absorber, plasticizer, lubricant and compatibilizer into the mixer, and stir and mix for 15-25 minutes at a temperature of 50-60℃ and a stirring speed of 600-800r / min to obtain the premix. Step 3: Add the premixed material to a twin-screw extruder and melt-extrude it at a temperature of 170-180℃ and a screw speed of 50-100r / min. Then, calender it to obtain a modified recycled polyethylene geomembrane.

8. The method for preparing a modified recycled polyethylene geomembrane according to claim 7, characterized in that, The plasticizer is one of dimethyl phthalate, dibutyl phthalate, and dioctyl phthalate.

9. The method for preparing a modified recycled polyethylene geomembrane according to claim 7, characterized in that, The compatibilizer is one of PE-g-ST and PE-g-MAH.

10. The method for preparing a modified recycled polyethylene geomembrane according to claim 7, characterized in that, The lubricant is one of stearic acid, butyl stearate, and polyethylene wax.

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