High-strength anti-aging soft plastic and preparation method thereof

Abstract

The invention discloses high-strength anti-aging soft plastic and a preparation method thereof, and relates to the technical field of plastic. The high-strength anti-aging soft plastic is prepared from a cerium-based metal frame core-shell structure modifier, a nano composite heat stabilizer, a low-temperature-resistant plasticizer, a silicon dioxide filler, calcium stearate and polyvinyl chloride, the cerium-based metal frame core-shell structure modifier is composed of a cerium-based metal frame, carboxylated graphene oxide and a lignin liquefied product; the nano composite heat stabilizer is an N-Ag co-doped and modified nano titanium dioxide compound; by adding the cerium-based metal frame core-shell structure modifier and the nano-composite heat stabilizer into the polyvinyl chloride matrix, the compatibility and dispersity of all the components are improved, the strength and aging resistance are remarkably improved, and the use durability of the soft plastic is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of plastics, and specifically refers to a high-strength and anti-aging soft plastic and its preparation method. Background Art

[0002] Soft plastic refers to a plastic material with certain softness and toughness, which has better impact resistance, toughness and plasticity compared with hard plastic; soft plastic can be heated and formed into various shapes, and different formula materials can be added to adjust its hardness, fire resistance, weather resistance, durability and other properties. In addition, soft plastic can be combined with various materials, such as metals, textiles, glass, etc. These properties make soft plastic widely used in many fields.

[0003] PVC (polyvinyl chloride) is one of the most common soft plastics, which is applied in the fields of medical treatment, construction, electronics, automobiles, etc.; soft plastics are widely used in daily life, such as plastic bags, plastic chassis, plastic hangers, etc. These products have the characteristics of being light, tough, waterproof, moisture-proof, etc., which facilitate our life and cleaning of daily necessities; soft plastics are widely used in the manufacturing industry, such as automobile interiors, electrical appliances, electronic products, etc. They are mostly used to manufacture internal structural parts, electronic components, cables, cable protection sleeves, etc. These products have the characteristics of being durable, delicate, long-lasting, insulating, fireproof, etc.; soft plastics are also applied in the field of healthcare, such as surgical instruments, medicine bottles, infusion bags, etc. Medical devices made of soft plastics have good biocompatibility and can reduce the risk of infection.

[0004] Currently, the following problems mainly exist in the prior art:

[0005] The strength of soft plastic is relatively low, and it is easy to deform or be damaged under the influence of greater external force. In addition, soft plastic products are prone to aging after long-term use, which affects their service life and performance. Summary of the Invention

[0006] In view of the above situation, in order to overcome the defects of the prior art, the present invention provides a high-strength and anti-aging soft plastic, which comprises the following components in parts by weight: 10-15 parts of a cerium-based metal framework core-shell structure modifier, 15-25 parts of a nano composite heat stabilizer, 30-40 parts of a low-temperature resistant plasticizer, 20-25 parts of a silica filler, 2-5 parts of calcium stearate, and 90-100 parts of polyvinyl chloride.

[0007] The cerium-based metal framework core-shell structure modifier comprises the following components in parts by weight: 10-20 parts of a cerium-based metal framework, 10-20 parts of carboxylated graphene oxide, and 10-20 parts of lignin liquefaction product.

[0008] The nano composite heat stabilizer is an N-Ag co-doped modified nano titanium dioxide composite.

[0009] The low-temperature resistant plasticizer is bis(2-propylheptyl) adipate synthesized from 2-propylheptanol and adipic acid as raw materials.

[0010] The preparation method of the cerium-based metal-organic framework core-shell structure modifier specifically includes the following steps:

[0011] (1) Dissolve 0.5 - 0.6 g of ammonium cerium nitrate powder in 15 mL of deionized water, and dissolve 0.2 g of terephthalic acid powder in 30 mL of N,N-dimethylformamide. Then mix these two solutions and stir for 3 min. Place the obtained mixed solution in a reaction kettle and heat it at 100 - 110 °C for 20 - 30 min. After cooling to 25 °C, centrifuge to obtain the separated product, and then wash the product 3 - 5 times with 50 mL of N,N-dimethylformamide and 50 mL of deionized water respectively to fully remove the unreacted terephthalic acid. Dry it. The addition of rare earth elements can improve the strength and hardness of plastics, and cerium elements can also absorb ultraviolet rays to prevent the damage of ultraviolet rays to plastics, thereby protecting plastics from the influence of ultraviolet aging, and obtain a cerium-based metal-organic framework;

[0012] (2) Place 2.0 g of graphite powder, 50 mL of sulfuric acid solution with a mass fraction of 90 - 96%, and 0.6 - 1.0 g of sodium nitrate powder in a round-bottom flask. Under ice bath stirring, slowly add 6.0 - 8.0 g of potassium permanganate powder. Then place the reaction system in a water bath at 30 - 35 °C and stir for 1 h with a stirring speed of 1000 - 3000 rpm. Then slowly add 100 mL of water, 10 mL of hydrogen peroxide liquid with a mass fraction of 20 - 30%, and 300 mL of water in sequence. Let it stand overnight at 25 °C, then wash it to neutral, and perform ultrasonic filtration. Graphene oxide has the characteristics of high strength and high toughness. When its lamellar structure is dispersed in the polyvinyl chloride matrix, it can form a strengthened network structure, thereby improving the impact resistance and wear resistance of polyvinyl chloride, effectively enhancing the mechanical properties and service life. At the same time, graphene oxide can also improve the thermal stability and weather resistance of polyvinyl chloride, enabling it to remain stable at high temperatures or in harsh environments, and obtain a graphene oxide suspension;

[0013] (3) Add sodium hydroxide powder and chloroacetic acid powder to 30 - 50 mL of the graphene oxide suspension described in step (2), perform ultrasonic treatment for 2 - 3 h with an ultrasonic power of 600 - 800 W, then filter and evaporate. The carboxylation of graphene oxide can enhance the surface hydrophilicity, making it easier to be uniformly dispersed in water or other solvents, and at the same time also enhancing the interaction with other substances. Dry it to obtain carboxylated graphene oxide;

[0014] (4) dissolving the carboxylated graphene oxide described in step (3) in N,N-dimethylformamide, and then adding the cerium-based metal framework described in step (1), heating the reaction for 10-12 hours, and controlling the temperature to be 100-120°C. The cerium-based metal framework has a high specific surface area and a developed pore structure. This structural feature enables it to effectively disperse and fix the carboxylated graphene oxide. The cerium-based metal framework and the carboxylated graphene oxide form a composite, presenting a smooth surface of a cube and a polyhedron. As the core material, the two synergistically enhance the strength and anti-aging properties of plastics such as polyvinyl chloride, thereby obtaining a cerium-based metal framework composite core material;

[0015] (5) Place the lignin in a 120°C oven for dehydration and drying for 120 min, weigh 6.0 g of the treated lignin, 24.0 g of polyethylene glycol-600 and 6.0 g of propylene glycol and place them in a round-bottom flask. After fully stirring on a constant temperature magnetic stirrer, use a pipette to draw 0.5 mL of a 98% sulfuric acid solution and drip it in. Continue stirring for 30 min, transfer the round-bottom flask to a microwave synthesis extractor, and naturally cool the lignin to 70°C after liquefaction. Vacuum filter to remove the residual solids, and dry the filtrate. Lignin has rich active groups and good biodegradability, but its reaction activity is low and its compatibility with polymers is poor, resulting in low effective utilization. Through liquefaction treatment, lignin can be converted into aromatic compounds, hydrocarbons, esters and ketones. These compounds can be blended with polyvinyl chloride to better improve the performance of polyvinyl chloride and obtain lignin liquefied product;

[0016] (6) The cerium-based metal framework composite core material described in step (4) and the lignin liquefied material described in step (5) are weighed in a mass ratio of 2:1 and placed in a ball mill, grinding balls with a diameter of 4 mm are added, the ball-to-material mass ratio is 40:1, the ball mill speed is 300-400 rpm, and the forward and reverse rotations are performed for 2 hours each, so that a mechanochemical reaction occurs, and the lignin liquefied material coats the cerium-based metal framework composite core material to form a core-shell structure. The shell material lignin liquefied material is equivalent to a compatibilizer, which improves the good dispersibility of the core material in polyvinyl chloride, and obtains a cerium-based metal framework core-shell structure modifier;

[0017] Preferably, in step (3), the amount of sodium hydroxide added is 5.0-6.0 g, and the amount of chloroacetic acid added is 4.0-5.0 g, and during the reaction, the epoxy groups and hydroxyl groups on the graphene oxide can be converted into carboxyl groups;

[0018] Preferably, in step (5), during the treatment of the microwave synthesis extraction instrument, the power is controlled to be 500-600 W, the reaction temperature is 140-160° C., and the reaction time is 10-20 min. The polar molecules are rapidly turned and frictionally heated by microwave radiation, thereby efficiently converting lignin.

[0019] The preparation method of the nano composite heat stabilizer specifically comprises the following steps:

[0020] Mix 10 mL of tetrabutyl titanate and 30 - 40 mL of absolute ethanol to obtain solution A. Then mix 25 - 35 mL of absolute ethanol, 10 mL of deionized water and 20 mL of glacial acetic acid, add a nitric acid solution with a mass fraction of 65% dropwise to adjust the pH of the solution ≤ 3, add silver nitrate and urea solids, and stir evenly to obtain solution B. Under the action of a strong magnetic stirrer, slowly add solution A drop by drop to solution B to enable them to react fully. After the addition is completed, stir for 30 min to obtain a white transparent colloid, let it age for 24 h, dry it and then place it in a muffle furnace for calcination treatment. During the calcination process, first heat up to 350 °C, increase the temperature by 10 °C each time until it reaches 430 °C, then carry out the calcination treatment for 200 min, cool it down to room temperature, and grind it. Using tetrabutyl titanate as the source of precursor titanium, silver nitrate as the source of Ag, and urea as the source of N, through the calcination process, N - Ag co - doped modified nano - titanium dioxide is obtained, effectively improving the thermal stability of nano - titanium dioxide. Doping modification is also beneficial to the dispersion of nano - titanium dioxide, enabling it to be evenly dispersed in the polyvinyl chloride matrix, significantly enhancing the strength, durability and anti - aging properties of plastics, and obtaining the nano composite heat stabilizer;

[0021] Preferably, the addition amount of silver nitrate is 0.05 - 0.1 g, and the addition amount of urea is 0.3 - 0.5 g. The doping of silver ions can reduce the band gap of titanium dioxide, and nitrogen elements can improve the electronic structure and surface properties of titanium dioxide, thereby enhancing its thermal stability and anti - ultraviolet performance.

[0022] The present invention also provides a preparation method of a high - strength anti - aging soft plastic, which specifically comprises the following steps:

[0023] S1. Put 2 - propylheptanol liquid and adipic acid solid into a four - necked flask equipped with a stirrer, a thermometer, a condenser and a water separator according to a molar ratio of 1:2.5, add a titanate catalyst according to 0.3% of the total mass of 2 - propylheptanol and adipic acid, start stirring, heat up to 180 °C to start water reflux, separate and collect the water carried out by 2 - propylheptanol, and the alcohol refluxes to the flask to continue participating in the reaction. When the acid value of the reaction product in terms of potassium hydroxide reaches below 0.2 mg / g, the reaction ends. Cool the reaction material to 90 °C, neutralize and wash it with a 5% sodium hydroxide solution, let it stand for layering to remove the aqueous phase, and subject the obtained crude ester to vacuum distillation, and then filter and decolorize it through activated carbon. The dioctyl adipate prepared by this process is a functional plasticizer, which broadens the scope of use, can improve the cold resistance of polyvinyl chloride plastics, reduce cracks and breakage caused by low temperature, and is beneficial to the durability of plastic products, obtaining a low - temperature resistant plasticizer;

[0024] S2. Uniformly mix the low-temperature resistant plasticizer, cerium-based metal framework core-shell structure modifier, nano composite heat stabilizer, silica filler, calcium stearate, and polyvinyl chloride described in step S1 at a mixing speed of 600 - 1000 rpm for 30 - 50 min. Then, put the mixed material into a twin-screw granulator for granulation. By adding the cerium-based metal framework core-shell structure modifier and nano composite heat stabilizer, the mechanical properties and thermal stability of polyvinyl chloride are significantly enhanced, and a high-strength and anti-aging soft plastic is obtained;

[0025] Preferably, in step S1, the titanate catalyst is tetrabutyl titanate. Tetrabutyl titanate is an efficient catalyst applied to various organic synthesis reactions. It can significantly reduce the reaction temperature, reduce the generation of by-products, and improve the reaction efficiency and product purity.

[0026] The beneficial effects obtained by the present invention are as follows:

[0027] In the present invention, by adding a cerium-based metal framework core-shell structure modifier and a nano composite heat stabilizer to the polyvinyl chloride matrix, the compatibility and dispersibility of each component are improved, the strength and anti-aging performance are significantly enhanced, and the durability of the soft plastic is increased; in the cerium-based metal framework core-shell structure modifier, the cerium-based metal framework and carboxylated graphene oxide are used as core substances. Among them, carboxylated graphene oxide is dispersed and fixed on the pores of the cerium-based metal framework, and the lignin liquefied product is used as the shell layer substance to form a core-shell structure coating. The lignin liquefied product not only enhances the strength, toughness, and thermal stability of polyvinyl chloride, but also can be used as a compatibilizer, enabling the core substances to be well dispersed in the polyvinyl chloride matrix, thereby better exerting the efficacy of the cerium-based metal framework and carboxylated graphene oxide in enhancing the strength and anti-aging properties of polyvinyl chloride plastics; in the nano composite heat stabilizer, nano titanium dioxide modified by N-Ag co-doping is formed, effectively improving the thermal stability and anti-ultraviolet performance of nano titanium dioxide. The doping modification is also beneficial to the dispersion of nano titanium dioxide, enabling it to be uniformly dispersed in the polyvinyl chloride matrix, which is beneficial to improving the strength and anti-aging of the plastic and has better durability; the co-addition of the core-shell structure and nano powder forms a synergistic effect of two levels of micron and nano substances, which can be more fully dispersed in the space of the polyvinyl chloride matrix, improving the uniformity and efficiency of polyvinyl chloride modification; at the same time, the addition of the low-temperature resistant plasticizer endows the soft plastic with cold resistance, which can reduce cracks and damage caused by low temperature, is beneficial to the durability of plastic products, and extends the service life; the present invention uses a cerium-based metal framework core-shell structure modifier, a nano composite heat stabilizer, a low-temperature resistant plasticizer, a silica filler, calcium stearate, and polyvinyl chloride to make a high-strength and anti-aging soft plastic, effectively enhancing the strength and anti-aging performance of plastic products and significantly extending the service life. Description of the Drawings

[0028] Figure 1 Scanning electron microscope image of the cerium-based metal framework core-shell structure modifier prepared in Example 1 of the present invention;

[0029] Figure 2 Scanning electron microscope image of the nano-composite heat stabilizer prepared in Example 1 of the present invention;

[0030] Figure 3 Scanning electron microscope image of the cross-section of the high-strength anti-aging soft plastic prepared in Example 1 of the present invention;

[0031] Figure 4 Graph of the mechanical property results of Examples 1-4 and Comparative Examples 1-3 of the present invention;

[0032] Figure 5 Graph of the anti-aging results of Examples 1-4 and Comparative Examples 1-3 of the present invention. Detailed implementation manners

[0033] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments; based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0034] Unless otherwise defined, all professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to the described content can be applied to the present invention. The preferred implementation methods and materials described herein are only for demonstration purposes, but cannot limit the content of this application.

[0035] The experimental methods in the following embodiments are all conventional methods unless otherwise specified; the test materials used in the following embodiments are all obtained from commercial channels unless otherwise specified.

[0036] The sources of the reagents used in the examples are as follows:

[0037] Ammonium cerium nitrate CAS No: 16774-21-3, brand Innochem, product number A47392;

[0038] Terephthalic acid CAS No: 100-21-0, brand Innochem, product number A68313;

[0039] N,N-dimethylformamide CAS No: 68-12-2, brand Innochem, product number A04779;

[0040] Chloroacetic acid, CAS No: 79-11-8, brand Tci, item number C2123;

[0041] Lignin, CAS No: 9005-53-2, brand Innochem, item number A68428;

[0042] Polyethylene glycol - 600, CAS No: 25322-68-3, brand Innochem, item number A04817;

[0043] Glycerol, CAS No: 56-81-5, brand Innochem, item number A13031;

[0044] Graphite powder, CAS No: 7782-42-5, brand Innochem, item number A11220;

[0045] Sulfuric acid, CAS No: 7664-93-9, brand Acros, item number 124640025;

[0046] Sodium nitrate, CAS No: 7631-99-4, brand Alfa, item number 014493;

[0047] Potassium permanganate, CAS No: 7722-64-7, brand Acros, item number 424170025;

[0048] Hydrogen peroxide, CAS No: 7722-84-1, brand Acros, item number 202460010;

[0049] Tetrabutyl titanate, CAS No: 5593-70-4, brand Innochem, item number A23235;

[0050] Glacial acetic acid, CAS No: 64-19-7, brand Innochem, item number A27238;

[0051] Nitric acid, CAS No: 7697-37-2, brand Acros, item number 124660010;

[0052] Silver nitrate, CAS No: 7761-88-8, brand Acros, item number 197680025;

[0053] Urea, CAS No: 57-13-6, brand Innochem, item number A68476;

[0054] 2-Propylheptanol, CAS No: 10042-59-8, brand Apinno, item number GC66290;

[0055] Adipic acid, CAS No: 124-04-9, brand Innochem, product number A33263;

[0056] Silicon dioxide, CAS No: 60676-86-0, brand Innochem, product number A72352;

[0057] Calcium stearate, CAS No: 1592-23-0, brand Apinno, product number GC106706;

[0058] Polyvinyl chloride, CAS No: 9002-86-2, brand Innochem, product number A72818;

[0059] Sodium hydroxide, CAS No: 1310-73-2, brand Innochem, product number A36865;

[0060] Absolute ethanol, CAS No: 64-17-5, brand Innochem, product number G00004.

[0061] Example 1

[0062] This example presents a high-strength and anti-aging soft plastic, which includes the following components in parts by weight: 15 parts of cerium-based metal framework core-shell structure modifier, 25 parts of nano composite heat stabilizer, 40 parts of low-temperature resistant plasticizer, 25 parts of silicon dioxide filler, 5 parts of calcium stearate, and 100 parts of polyvinyl chloride.

[0063] The cerium-based metal framework core-shell structure modifier includes the following components in parts by weight: 20 parts of cerium-based metal framework, 20 parts of carboxylated graphene oxide, and 20 parts of lignin liquefied product.

[0064] The nano composite heat stabilizer is an N-Ag co-doped modified nano titanium dioxide composite.

[0065] The low-temperature resistant plasticizer is bis(2-propylheptyl) adipate synthesized from 2-propylheptanol and adipic acid as raw materials.

[0066] The preparation method of the cerium-based metal framework core-shell structure modifier specifically includes the following steps:

[0067] (1) Dissolve 0.6 g of ammonium cerium(IV) nitrate powder in 15 mL of deionized water, and dissolve 0.2 g of terephthalic acid powder in 30 mL of N,N-dimethylformamide. Then mix these two solutions and stir for 3 min. Place the resulting mixed solution in a reaction kettle and heat it at 110 °C for 30 min. After cooling to 25 °C, centrifuge to obtain the separated product, and then wash the product 5 times with 50 mL of N,N-dimethylformamide and 50 mL of deionized water respectively to fully remove the unreacted terephthalic acid. Dry it. The addition of rare earth elements can improve the strength and hardness of plastics, and cerium elements can also absorb ultraviolet rays to prevent the damage of ultraviolet rays to plastics, thereby protecting plastics from ultraviolet aging, and obtain a cerium-based metal framework;

[0068] (2) Place 2.0 g of graphite powder, 50 mL of sulfuric acid solution with a mass fraction of 96%, and 1.0 g of sodium nitrate powder in a round-bottom flask. Under ice bath stirring, slowly add 8.0 g of potassium permanganate powder. Then place the reaction system in a 35 °C water bath and stir for 1 h with a stirring speed of 3000 rpm. Then slowly add 100 mL of water, 10 mL of hydrogen peroxide liquid with a mass fraction of 30%, and 300 mL of water in sequence. Let it stand overnight at 25 °C, then wash it to neutral, and perform ultrasonic filtration. Graphene oxide has the characteristics of high strength and high toughness. When its lamellar structure is dispersed in the polyvinyl chloride matrix, it can form a strengthening network structure, thereby improving the impact resistance and wear resistance of polyvinyl chloride, effectively enhancing the mechanical properties and service life. At the same time, graphene oxide can also improve the thermal stability and weather resistance of polyvinyl chloride, enabling it to remain stable at high temperatures or in harsh environments, and obtain a graphene oxide suspension;

[0069] (3) Add sodium hydroxide powder and chloroacetic acid powder to 50 mL of the graphene oxide suspension described in step (2). The addition amount of sodium hydroxide is 6.0 g, and the addition amount of chloroacetic acid is 5.0 g. During the reaction, the epoxy groups and hydroxyl groups on graphene oxide can be converted into carboxyl groups. Perform ultrasonic treatment for 3 h with an ultrasonic power of 800 W, and then filter and evaporate. The carboxylation of graphene oxide can enhance the surface hydrophilicity, making it easier to be evenly dispersed in water or other solvents, and at the same time also enhancing the interaction with other substances. Dry it to obtain carboxylated graphene oxide;

[0070] (4) dissolving the carboxylated graphene oxide described in step (3) in N,N-dimethylformamide, and then adding the cerium-based metal framework described in step (1), heating the reaction for 12 hours, and controlling the temperature to be 120°C. The cerium-based metal framework has a high specific surface area and a developed pore structure. This structural feature enables it to effectively disperse and fix the carboxylated graphene oxide. The cerium-based metal framework and the carboxylated graphene oxide form a composite, presenting a smooth surface of a cube and a polyhedron. As the core material, the two synergistically enhance the strength and anti-aging properties of plastics such as polyvinyl chloride, thereby obtaining a cerium-based metal framework composite core material;

[0071] (5) Place the lignin in a 120°C oven for dehydration and drying for 120 min. Weigh 6.0 g of the treated lignin, 24.0 g of polyethylene glycol-600 and 6.0 g of propylene glycol and place them in a round-bottom flask. After fully stirring on a constant temperature magnetic stirrer, use a pipette to draw 0.5 mL of 98% sulfuric acid solution and drip it in. Continue stirring for 30 min. Transfer the round-bottom flask to a microwave synthesis extractor. After the lignin is liquefied, naturally cool it to 70°C. During the microwave synthesis extractor treatment, the power is controlled at 600 W and the reaction temperature is controlled at 250 °C. 160℃, reaction time 20min, microwave radiation is used to make polar molecules turn quickly and generate heat through friction, so as to efficiently convert lignin, vacuum filtration is used to remove residual solids, and the filtrate is dried. Lignin has abundant active groups and good biodegradability, but its reaction activity is low and its compatibility with polymers is poor, resulting in low effective utilization rate. Through liquefaction treatment, lignin can be converted into aromatic compounds, hydrocarbons, esters and ketones, etc. These compounds can be blended with polyvinyl chloride to better improve the performance of polyvinyl chloride and obtain lignin liquefied product;

[0072] (6) The cerium-based metal framework composite core material described in step (4) and the lignin liquefied material described in step (5) are weighed in a mass ratio of 2:1 and placed in a ball mill. Grinding balls with a diameter of 4 mm are added. The ball-to-material mass ratio is 40:1. The ball mill speed is 400 rpm. The forward and reverse rotations are performed for 2 hours each to allow a mechanochemical reaction to occur. The lignin liquefied material coats the cerium-based metal framework composite core material to form a core-shell structure. The shell material lignin liquefied material is equivalent to a compatibilizer, which improves the good dispersibility of the core material in polyvinyl chloride, thereby obtaining a cerium-based metal framework core-shell structure modifier.

[0073] The preparation method of the nanocomposite thermal stabilizer specifically comprises the following steps:

[0074] Mix 10 mL of tetrabutyl titanate and 40 mL of absolute ethanol to obtain solution A. Then mix 35 mL of absolute ethanol, 10 mL of deionized water, and 20 mL of glacial acetic acid. Dropwise add a nitric acid solution with a mass fraction of 65% to adjust the pH of the solution to ≤3. Add silver nitrate and urea solids and stir evenly to obtain solution B. The addition amount of silver nitrate is 0.1 g, and the addition amount of urea is 0.5 g. The doping of silver ions can reduce the band gap of titanium dioxide, and nitrogen elements can improve the electronic structure and surface properties of titanium dioxide, thereby enhancing its thermal stability and ultraviolet resistance. Under the action of a strong magnetic stirrer, slowly add solution A drop by drop to solution B to enable them to react fully. After the addition is completed, stir for 30 min to obtain a white transparent colloid, let it age for 24 h, dry it, and then calcine it in a muffle furnace. During the calcination process, first heat up to 350 °C, increase the temperature by 10 °C each time until it reaches 430 °C, then calcine for 200 min, cool down to room temperature, and grind. Using tetrabutyl titanate as the precursor source of titanium, silver nitrate as the source of Ag, and urea as the source of N, through the calcination process, N-Ag co-doped modified nano-titanium dioxide is obtained, effectively improving the thermal stability of nano-titanium dioxide. Doping modification is also beneficial to the dispersion of nano-titanium dioxide, enabling it to be evenly dispersed in the polyvinyl chloride matrix, significantly enhancing the strength, durability, and anti-aging properties of the plastic, and obtaining a nano-composite heat stabilizer.

[0075] This example provides a method for preparing a high-strength and anti-aging soft plastic, which specifically includes the following steps:

[0076] S1. Put 2-propylheptanol liquid and adipic acid solid into a four-necked flask equipped with a stirrer, thermometer, condenser, and water separator according to a molar ratio of 1:2.5. Add a titanate catalyst at 0.3% of the total mass of 2-propylheptanol and adipic acid. The titanate catalyst is tetrabutyl titanate. Tetrabutyl titanate is an efficient catalyst applied in various organic synthesis reactions. It can significantly reduce the reaction temperature, reduce the generation of by-products, improve the reaction efficiency and product purity. Start stirring and heat up to 180 °C to start water reflux. Separate and collect the water carried out by 2-propylheptanol. The alcohol refluxes to the flask to continue participating in the reaction. When the acid value of the reaction product in terms of potassium hydroxide reaches below 0.2 mg / g, the reaction ends. Cool the reaction material to 90 °C, neutralize and wash it with a 5% sodium hydroxide solution, let it stand and separate to remove the aqueous phase, and subject the obtained crude ester to vacuum distillation, and then filter and decolorize it through activated carbon. The obtained bis(2-propylheptyl) adipate prepared by this process is a functional plasticizer, which broadens the application range, can improve the cold resistance of polyvinyl chloride plastics, reduce cracks and damages caused by low temperature, and is beneficial to the durability of plastic products, obtaining a low-temperature resistant plasticizer;

[0077] S2. Mix the low-temperature resistant plasticizer, cerium-based metal framework core-shell structure modifier, nano composite heat stabilizer, silica filler, calcium stearate, and polyvinyl chloride described in step S1 evenly at a mixing speed of 1000 rpm for 50 min. Then, put the mixed material into a twin-screw granulator for granulation. By adding the cerium-based metal framework core-shell structure modifier and nano composite heat stabilizer, the mechanical properties and thermal stability of polyvinyl chloride are significantly enhanced, and a high-strength anti-aging soft plastic is obtained.

[0078] In this example, a scanning electron microscope was used to scan the cross-section of the prepared cerium-based metal framework core-shell structure modifier, nano composite heat stabilizer, and high-strength anti-aging soft plastic to observe their microtopographies. Figure 1 SEM image of the cerium-based metal framework core-shell structure modifier prepared in Example 1 magnified 400 times. Figure 2 SEM image of the nano composite heat stabilizer prepared in Example 1 magnified 100000 times. Figure 3 SEM image of the cross-section of the high-strength anti-aging soft plastic prepared in Example 1 magnified 1000 times. As Figure 1 , the cerium-based metal framework core-shell structure modifier prepared in this example is a core-shell structure coating. As Figure 2 , the nano composite heat stabilizer prepared in this example is doped and modified nano titanium dioxide. As Figure 3 , the cross-section of the high-strength anti-aging soft plastic prepared in this example is flat and uniform, and has good compatibility.

[0079] Example 2

[0080] This example presents a high-strength anti-aging soft plastic, which includes the following components in parts by weight: 10 parts of cerium-based metal framework core-shell structure modifier, 15 parts of nano composite heat stabilizer, 30 parts of low-temperature resistant plasticizer, 20 parts of silica filler, 2 parts of calcium stearate, and 90 parts of polyvinyl chloride.

[0081] The cerium-based metal framework core-shell structure modifier includes the following components in parts by weight: 10 parts of cerium-based metal framework, 10 parts of carboxylated graphene oxide, and 10 parts of lignin liquefied product.

[0082] The nano composite heat stabilizer is an N-Ag co-doped modified nano titanium dioxide composite.

[0083] The low-temperature resistant plasticizer is bis(2-propylheptyl) adipate synthesized from 2-propylheptanol and adipic acid.

[0084] The preparation method of the cerium-based metal framework core-shell structure modifier specifically includes the following steps:

[0085] (1) Dissolve 0.5 g of ammonium cerium(IV) nitrate powder in 15 mL of deionized water, and dissolve 0.2 g of terephthalic acid powder in 30 mL of N,N-dimethylformamide. Then mix these two solutions and stir for 3 min. Place the resulting mixed solution in a reaction kettle and heat it at 100 °C for 20 min. After cooling to 25 °C, centrifuge to obtain the separated product, and then wash the product 3 times with 50 mL of N,N-dimethylformamide and 50 mL of deionized water respectively to fully remove the unreacted terephthalic acid. Dry it. The addition of rare earth elements can improve the strength and hardness of plastics, and cerium elements can also absorb ultraviolet rays to prevent the damage of plastics by ultraviolet rays, thereby protecting plastics from ultraviolet aging, and obtain a cerium-based metal framework;

[0086] (2) Place 2.0 g of graphite powder, 50 mL of sulfuric acid solution with a mass fraction of 90%, and 0.6 g of sodium nitrate powder in a round-bottom flask. Under ice bath stirring, slowly add 6.0 g of potassium permanganate powder. Then place the reaction system in a 30 °C water bath and stir for 1 h with a stirring speed of 1000 rpm. Then slowly add 100 mL of water, 10 mL of hydrogen peroxide liquid with a mass fraction of 20%, and 300 mL of water in sequence. Let it stand overnight at 25 °C, then wash it to neutral, and perform ultrasonic filtration. Graphene oxide has the characteristics of high strength and high toughness. When its lamellar structure is dispersed in the polyvinyl chloride matrix, it can form a strengthened network structure, thereby improving the impact resistance and wear resistance of polyvinyl chloride, effectively enhancing the mechanical properties and service life. At the same time, graphene oxide can also improve the thermal stability and weather resistance of polyvinyl chloride, enabling it to remain stable at high temperatures or in harsh environments, and obtain a graphene oxide suspension;

[0087] (3) Add sodium hydroxide powder and chloroacetic acid powder to 30 mL of the graphene oxide suspension described in step (2). The addition amount of sodium hydroxide is 5.0 g, and the addition amount of chloroacetic acid is 4.0 g. During the reaction process, the epoxy groups and hydroxyl groups on graphene oxide can be converted into carboxyl groups. Perform ultrasonic treatment for 2 h with an ultrasonic power of 600 W, and then filter and evaporate. The carboxylation of graphene oxide can enhance the surface hydrophilicity, making it easier to be evenly dispersed in water or other solvents, and at the same time also enhancing the interaction with other substances. Dry it to obtain carboxylated graphene oxide;

[0088] (4) dissolving the carboxylated graphene oxide described in step (3) in N,N-dimethylformamide, and then adding the cerium-based metal framework described in step (1), heating the reaction for 10 hours, and controlling the temperature to be 100°C. The cerium-based metal framework has a high specific surface area and a developed pore structure. This structural feature enables it to effectively disperse and fix the carboxylated graphene oxide. The cerium-based metal framework and the carboxylated graphene oxide form a composite, presenting a smooth surface of a cube and a polyhedron. As the core material, the two synergistically enhance the strength and anti-aging properties of plastics such as polyvinyl chloride, and obtain a cerium-based metal framework composite core material;

[0089] (5) Place the lignin in a 120°C oven for dehydration and drying for 120 min. Weigh 6.0 g of the treated lignin, 24.0 g of polyethylene glycol-600 and 6.0 g of propylene glycol and place them in a round-bottom flask. After fully stirring on a constant temperature magnetic stirrer, use a pipette to draw 0.5 mL of a 98% sulfuric acid solution and drip it in. Continue stirring for 30 min. Transfer the round-bottom flask to a microwave synthesis extractor. After the lignin is liquefied, naturally cool it to 70°C. During the microwave synthesis extractor treatment, control the power to 500 W and the reaction temperature to 140℃, reaction time 10min, microwave radiation is used to make polar molecules turn quickly and generate heat through friction, so as to efficiently convert lignin, vacuum filtration is used to remove residual solids, and the filtrate is dried. Lignin has abundant active groups and good biodegradability, but its reaction activity is low and its compatibility with polymers is poor, resulting in low effective utilization rate. Through liquefaction treatment, lignin can be converted into aromatic compounds, hydrocarbons, esters and ketones, etc. These compounds can be blended with polyvinyl chloride to better improve the performance of polyvinyl chloride and obtain lignin liquefied product;

[0090] (6) The cerium-based metal framework composite core material described in step (4) and the lignin liquefied material described in step (5) are weighed in a mass ratio of 2:1 and placed in a ball mill. Grinding balls with a diameter of 4 mm are added. The ball-to-material mass ratio is 40:1. The ball mill speed is 300 rpm. The forward and reverse rotations are performed for 2 hours each to allow a mechanochemical reaction to occur. The lignin liquefied material coats the cerium-based metal framework composite core material to form a core-shell structure. The shell material lignin liquefied material is equivalent to a compatibilizer, which improves the good dispersibility of the core material in polyvinyl chloride, thereby obtaining a cerium-based metal framework core-shell structure modifier.

[0091] The preparation method of the nanocomposite thermal stabilizer specifically comprises the following steps:

[0092] Mix 10 mL of tetrabutyl titanate and 30 mL of absolute ethanol to obtain solution A. Then mix 25 mL of absolute ethanol, 10 mL of deionized water and 20 mL of glacial acetic acid, and add a 65% nitric acid solution dropwise to adjust the pH of the solution to ≤3. Add silver nitrate and urea solids, stir evenly to obtain solution B. The addition amount of silver nitrate is 0.05 g, and the addition amount of urea is 0.3 g. The doping of silver ions can reduce the band gap of titanium dioxide, and nitrogen elements can improve the electronic structure and surface properties of titanium dioxide, thereby enhancing its thermal stability and ultraviolet resistance. Under the action of a strong magnetic stirrer, slowly add solution A drop by drop to solution B to enable them to react fully. After the addition is completed, stir for 30 min to obtain a white transparent colloid, let it age for 24 h, dry it and then calcine it in a muffle furnace. During the calcination process, first heat up to 350 °C, increase the temperature by 10 °C each time until it reaches 430 °C, then calcine for 200 min, cool down to room temperature, and grind. Using tetrabutyl titanate as the source of precursor titanium, silver nitrate as the source of Ag, and urea as the source of N, through the calcination process, N-Ag co-doped modified nano-titanium dioxide is obtained, effectively improving the thermal stability of nano-titanium dioxide. Doping modification is also beneficial to the dispersion of nano-titanium dioxide, enabling it to be evenly dispersed in the polyvinyl chloride matrix, significantly enhancing the strength, durability and anti-aging of plastics, and obtaining a nano composite heat stabilizer.

[0093] This example provides a method for preparing a high-strength and anti-aging soft plastic, which specifically includes the following steps:

[0094] S1. Put 2-propylheptanol liquid and adipic acid solid into a four-necked flask equipped with a stirrer, thermometer, condenser and water separator according to a molar ratio of 1:2.5, and add a titanate catalyst at 0.3% of the total mass of 2-propylheptanol and adipic acid. The titanate catalyst is tetrabutyl titanate. Tetrabutyl titanate is an efficient catalyst applied to various organic synthesis reactions, which can significantly reduce the reaction temperature, reduce the generation of by-products, improve the reaction efficiency and product purity. Start stirring, heat up to 180 °C to start water reflux, separate and collect the water carried out by 2-propylheptanol, and the alcohol refluxes to the flask to continue participating in the reaction. When the acid value of the reaction product reaches less than 0.2 mg / g in terms of potassium hydroxide, the reaction ends. Cool the reaction material to 90 °C, neutralize and wash it with a 5% sodium hydroxide solution, let it stand for layering to remove the aqueous phase, and subject the obtained crude ester to vacuum distillation, and then filter and decolorize it through activated carbon. The dioctyl adipate prepared by this process is a functional plasticizer, which broadens the scope of use, can improve the cold resistance of polyvinyl chloride plastics, reduce cracks and damages caused by low temperature, and is beneficial to the durability of plastic products, obtaining a low-temperature resistant plasticizer;

[0095] S2. Uniformly mix the low-temperature resistant plasticizer, cerium-based metal framework core-shell structure modifier, nano composite heat stabilizer, silica filler, calcium stearate, and polyvinyl chloride described in step S1 at a mixing speed of 600 rpm for 30 minutes. Then, put the mixed material into a twin-screw granulator for granulation. By adding the cerium-based metal framework core-shell structure modifier and nano composite heat stabilizer, the mechanical properties and thermal stability of polyvinyl chloride are significantly enhanced, and a high-strength anti-aging soft plastic is obtained.

[0096] Example 3

[0097] This example presents a high-strength anti-aging soft plastic, which includes the following components in parts by weight: 12.5 parts of cerium-based metal framework core-shell structure modifier, 20 parts of nano composite heat stabilizer, 35 parts of low-temperature resistant plasticizer, 22.5 parts of silica filler, 3.5 parts of calcium stearate, and 95 parts of polyvinyl chloride.

[0098] The cerium-based metal framework core-shell structure modifier includes the following components in parts by weight: 15 parts of cerium-based metal framework, 15 parts of carboxylated graphene oxide, and 15 parts of lignin liquefied product.

[0099] The nano composite heat stabilizer is an N-Ag co-doped modified nano titanium dioxide composite.

[0100] The low-temperature resistant plasticizer is bis(2-propylheptyl) adipate synthesized from 2-propylheptanol and adipic acid as raw materials.

[0101] The preparation method of the cerium-based metal framework core-shell structure modifier specifically includes the following steps:

[0102] (1) Dissolve 0.55 g of ammonium cerium nitrate powder in 15 mL of deionized water, and dissolve 0.2 g of terephthalic acid powder in 30 mL of N,N-dimethylformamide. Then, mix these two solutions and stir for 3 minutes. Place the resulting mixed solution in a reaction kettle and heat it at 105 °C for 25 minutes. After cooling to 25 °C, centrifuge to obtain the separated product, and then wash the product 4 times with 50 mL of N,N-dimethylformamide and 50 mL of deionized water respectively to fully remove the unreacted terephthalic acid. Dry it. The addition of rare earth elements can improve the strength and hardness of the plastic, and cerium elements can also absorb ultraviolet rays to prevent the destruction of the plastic by ultraviolet rays, thereby protecting the plastic from ultraviolet aging, and obtain a cerium-based metal framework;

[0103] (2) Place 2.0 g of graphite powder, 50 mL of sulfuric acid solution with a mass fraction of 93%, and 0.8 g of sodium nitrate powder in a round-bottom flask. Under ice bath stirring, slowly add 7.0 g of potassium permanganate powder. Then place the reaction system in a water bath at 32.5 °C and stir for 1 h at a stirring speed of 2000 rpm. Then, slowly add 100 mL of water, 10 mL of hydrogen peroxide liquid with a mass fraction of 25%, and 300 mL of water in sequence. Let it stand overnight at 25 °C, then wash until neutral, and perform ultrasonic filtration. Graphene oxide has the characteristics of high strength and high toughness. When its sheet structure is dispersed in a polyvinyl chloride matrix, it can form a strengthened network structure, thereby improving the impact resistance and wear resistance of polyvinyl chloride, effectively enhancing the mechanical properties and service life. At the same time, graphene oxide can also improve the thermal stability and weather resistance of polyvinyl chloride, enabling it to remain stable at high temperatures or in harsh environments, and obtain a graphene oxide suspension;

[0104] (3) Add sodium hydroxide powder and chloroacetic acid powder to 40 mL of the graphene oxide suspension described in step (2). The addition amount of sodium hydroxide is 5.5 g, and the addition amount of chloroacetic acid is 4.5 g. During the reaction, the epoxy groups and hydroxyl groups on the graphene oxide can be converted into carboxyl groups. Perform ultrasonic treatment for 2.5 h with an ultrasonic power of 700 W, then filter and evaporate. The carboxylation of graphene oxide can enhance the surface hydrophilicity, making it easier to disperse uniformly in water or other solvents. At the same time, it also enhances the interaction with other substances. Dry to obtain carboxylated graphene oxide;

[0105] (4) Dissolve the carboxylated graphene oxide described in step (3) in N,N-dimethylformamide, and then add the cerium-based metal framework described in step (1). Heat and react for 11 h, controlling the temperature at 110 °C. The cerium-based metal framework has a high specific surface area and a developed pore structure. This structural feature enables it to effectively disperse and fix the carboxylated graphene oxide. The cerium-based metal framework and the carboxylated graphene oxide form a composite, presenting smooth cubes and polyhedrons on the surface. As the core substance, the two work together to enhance the strength and anti-aging performance of plastics such as polyvinyl chloride, and obtain a cerium-based metal framework composite core;

[0106] (5) Place the lignin in an oven at 120 °C for dehydration drying treatment for 120 min. Weigh 6.0 g of the treated lignin, 24.0 g of polyethylene glycol - 600, and 6.0 g of glycerol and put them into a round - bottom flask. After stirring thoroughly on a constant - temperature magnetic stirrer, use a pipette to suck 0.5 mL of sulfuric acid solution with a mass fraction of 98% and drop it in, then continue stirring for 30 min. Transfer the round - bottom flask to a microwave synthesis extraction instrument. After the lignin liquefaction is completed, let it cool naturally to 70 °C. During the treatment process of the microwave synthesis extraction instrument, control the power at 550 W, the reaction temperature at 150 °C, and the reaction time at 15 min. Through microwave radiation, polar molecules rapidly turn and generate heat by friction, thereby efficiently converting lignin. Perform vacuum filtration to remove the residual solid, and dry the filtrate. Lignin has rich active groups and good biodegradability, but its reaction activity is low and its compatibility with polymers is poor, resulting in low effective utilization rate. Through liquefaction treatment, lignin can be converted into compounds such as aromatics, hydrocarbons, esters, and ketones. These compounds can be blended with polyvinyl chloride to better improve the performance of polyvinyl chloride, and obtain lignin liquefied products;

[0107] (6) Weigh the cerium - based metal - organic framework composite core material described in step (4) and the lignin liquefied product described in step (5) according to a mass ratio of 2:1 and put them into a ball - milling tank. Add grinding balls with a diameter of 4 mm, with a ball - to - material mass ratio of 40:1, and a ball - milling rotation speed of 350 rpm. Rotate forward and backward for 2 h each to make them undergo a mechanochemical reaction. The lignin liquefied product coats the cerium - based metal - organic framework composite core material to form a core - shell structure. The lignin liquefied product in the shell layer acts as a compatibilizer, improving the good dispersibility of the core material in polyvinyl chloride, and obtaining a cerium - based metal - organic framework core - shell structure modifier.

[0108] A preparation method of a nano - composite heat stabilizer specifically includes the following steps:

[0109] Mix 10 mL of tetrabutyl titanate and 35 mL of absolute ethanol to obtain solution A. Then mix 30 mL of absolute ethanol, 10 mL of deionized water and 20 mL of glacial acetic acid, and adjust the pH of the solution to ≤ 3 by dropping a nitric acid solution with a mass fraction of 65%. Add silver nitrate and urea solids and stir evenly to obtain solution B. The addition amount of silver nitrate is 0.075 g, and the addition amount of urea is 0.4 g. The doping of silver ions can reduce the band gap of titanium dioxide, and nitrogen elements can improve the electronic structure and surface properties of titanium dioxide, thereby enhancing its thermal stability and ultraviolet resistance. Under the action of a strong magnetic stirrer, slowly add solution A drop by drop to solution B to enable them to react fully. After the dropping is completed, stir for 30 min to obtain a white transparent colloid, let it age for 24 h, dry it and then place it in a muffle furnace for calcination treatment. During the calcination process, first heat up to 350 °C, increase by 10 °C each time until it reaches 430 °C, then calcine for 200 min, cool down to room temperature, and grind. Using tetrabutyl titanate as the precursor source of titanium, silver nitrate as the source of Ag, and urea as the source of N, through the calcination process, N-Ag co-doped modified nano-titanium dioxide is obtained, effectively improving the thermal stability of nano-titanium dioxide. Doping modification is also beneficial to the dispersion of nano-titanium dioxide, enabling it to be evenly dispersed in the polyvinyl chloride matrix, significantly enhancing the strength, durability and anti-aging of plastics, and obtaining a nano composite heat stabilizer.

[0110] This embodiment provides a method for preparing a high-strength and anti-aging soft plastic, which specifically includes the following steps:

[0111] S1. Put 2-propylheptanol liquid and adipic acid solid into a four-necked flask equipped with a stirrer, thermometer, condenser and water separator according to a molar ratio of 1:2.5, and add a titanate catalyst at 0.3% of the total mass of 2-propylheptanol and adipic acid. The titanate catalyst is tetrabutyl titanate. Tetrabutyl titanate is an efficient catalyst applied to various organic synthesis reactions, which can significantly reduce the reaction temperature, reduce the generation of by-products, improve the reaction efficiency and product purity. Start stirring and heat up to 180 °C to start water reflux. Separate and collect the water carried out by 2-propylheptanol, and the alcohol refluxes to the flask to continue participating in the reaction. When the acid value of the reaction product in terms of potassium hydroxide reaches below 0.2 mg / g, the reaction ends. Cool the reaction material to 90 °C, neutralize and wash it with a 5% sodium hydroxide solution, let it stand for layering to remove the aqueous phase, and subject the obtained crude ester to vacuum distillation, and then filter and decolorize it through activated carbon. The obtained bis(2-propylheptyl) adipate prepared by this process is a functional plasticizer, which broadens the scope of use, can improve the cold resistance of polyvinyl chloride plastics, reduce cracks and damages caused by low temperature, and is beneficial to the durability of plastic products, and a low-temperature resistant plasticizer is obtained;

[0112] S2. Uniformly mix the low-temperature resistant plasticizer, cerium-based metal framework core-shell structure modifier, nano composite heat stabilizer, silica filler, calcium stearate, and polyvinyl chloride described in step S1 at a mixing speed of 800 rpm for 40 minutes. Then, put the mixed material into a twin-screw granulator for granulation. By adding the cerium-based metal framework core-shell structure modifier and nano composite heat stabilizer, the mechanical properties and thermal stability of polyvinyl chloride are significantly enhanced, and a high-strength anti-aging soft plastic is obtained.

[0113] Example 4

[0114] This example presents a high-strength anti-aging soft plastic, which includes the following components in parts by weight: 15 parts of cerium-based metal framework core-shell structure modifier, 15 parts of nano composite heat stabilizer, 30 parts of low-temperature resistant plasticizer, 25 parts of silica filler, 5 parts of calcium stearate, and 100 parts of polyvinyl chloride.

[0115] The cerium-based metal framework core-shell structure modifier includes the following components in parts by weight: 20 parts of cerium-based metal framework, 20 parts of carboxylated graphene oxide, and 20 parts of lignin liquefied product.

[0116] The nano composite heat stabilizer is an N-Ag co-doped modified nano titanium dioxide composite.

[0117] The low-temperature resistant plasticizer is bis(2-propylheptyl) adipate synthesized from 2-propylheptanol and adipic acid as raw materials.

[0118] The preparation method of the cerium-based metal framework core-shell structure modifier specifically includes the following steps:

[0119] (1) Dissolve 0.6 g of ammonium cerium nitrate powder in 15 mL of deionized water, and dissolve 0.2 g of terephthalic acid powder in 30 mL of N,N-dimethylformamide. Then, mix these two solutions and stir for 3 minutes. Place the obtained mixed solution in a reaction kettle, heat it at 110 °C for 20 minutes, cool it to 25 °C, and then centrifuge to obtain a separated product. Wash the product 5 times with 50 mL of N,N-dimethylformamide and 50 mL of deionized water respectively to fully remove the unreacted terephthalic acid, and dry it. The addition of rare earth elements can improve the strength and hardness of the plastic, and cerium elements can also absorb ultraviolet light to prevent the destruction of the plastic by ultraviolet light, thereby protecting the plastic from ultraviolet aging, and obtaining a cerium-based metal framework;

[0120] (2) Place 2.0 g of graphite powder, 50 mL of sulfuric acid solution with a mass fraction of 96%, and 1.0 g of sodium nitrate powder in a round-bottom flask. Under ice bath stirring, slowly add 8.0 g of potassium permanganate powder. Then place the reaction system in a 35 °C water bath and stir for 1 h at a stirring speed of 3000 rpm. Then sequentially and slowly add 100 mL of water, 10 mL of hydrogen peroxide liquid with a mass fraction of 30%, and 300 mL of water. Let it stand overnight at 25 °C, then wash until neutral, and perform ultrasonic filtration. Graphene oxide has the characteristics of high strength and high toughness. When its sheet structure is dispersed in a polyvinyl chloride matrix, it can form a strengthening network structure, thereby improving the impact resistance and wear resistance of polyvinyl chloride, effectively enhancing the mechanical properties and service life. At the same time, graphene oxide can also improve the thermal stability and weather resistance of polyvinyl chloride, enabling it to remain stable at high temperatures or in harsh environments, and obtain a graphene oxide suspension;

[0121] (3) Add sodium hydroxide powder and chloroacetic acid powder to 30 - 50 mL of the graphene oxide suspension described in step (2). The addition amount of sodium hydroxide is 5.0 g, and the addition amount of chloroacetic acid is 4.0 g. During the reaction process, the epoxy groups and hydroxyl groups on the graphene oxide can be converted into carboxyl groups. Perform ultrasonic treatment for 2 h with an ultrasonic power of 800 W, then filter and evaporate. The carboxylation of graphene oxide can enhance the surface hydrophilicity, making it easier to be evenly dispersed in water or other solvents, and at the same time, it also enhances the interaction with other substances. Dry to obtain carboxylated graphene oxide;

[0122] (4) Dissolve the carboxylated graphene oxide described in step (3) in N,N-dimethylformamide, and then add the cerium-based metal framework described in step (1). Heat and react for 10 h, controlling the temperature at 120 °C. The cerium-based metal framework has a high specific surface area and a developed pore structure. This structural feature enables it to effectively disperse and fix the carboxylated graphene oxide. The cerium-based metal framework and the carboxylated graphene oxide form a complex, presenting smooth cubes and polyhedrons on the surface. As the core substance, the two work together to enhance the strength and anti-aging performance of plastics such as polyvinyl chloride, and obtain a cerium-based metal framework composite core;

[0123] (5) Place the lignin in an oven at 120 °C for dehydration drying for 120 min. Weigh 6.0 g of the treated lignin, 24.0 g of polyethylene glycol - 600, and 6.0 g of glycerol and put them into a round - bottom flask. After stirring thoroughly on a constant - temperature magnetic stirrer, use a pipette to suck 0.5 mL of sulfuric acid solution with a mass fraction of 98% and drop it in, and continue stirring for 30 min. Transfer the round - bottom flask to a microwave synthesis extractor. After the lignin liquefaction is completed, it is naturally cooled to 70 °C. During the treatment process of the microwave synthesis extractor, control the power at 600 W, the reaction temperature at 160 °C, and the reaction time at 10 min. Through microwave radiation, polar molecules quickly turn and generate heat by friction, thereby efficiently converting lignin. Perform vacuum filtration to remove the residual solid, and dry the filtrate. Lignin has rich active groups and good biodegradability, but its reaction activity is low and its compatibility with polymers is poor, resulting in its low effective utilization rate. Through liquefaction treatment, lignin can be converted into compounds such as aromatic, hydrocarbon, ester, and ketone compounds. These compounds can be blended with polyvinyl chloride, thereby better improving the performance of polyvinyl chloride to obtain a lignin liquefied product;

[0124] (6) Weigh the cerium - based metal - organic framework composite core material described in step (4) and the lignin liquefied product described in step (5) according to a mass ratio of 2:1 and put them into a ball - milling jar. Add grinding balls with a diameter of 4 mm, with a ball - to - material mass ratio of 40:1, and a ball - milling speed of 400 rpm. Rotate forward and reverse for 2 h each to cause a mechanochemical reaction. The lignin liquefied product coats the cerium - based metal - organic framework composite core material to form a core - shell structure. The lignin liquefied product in the shell layer acts as a compatibilizer, improving the good dispersion of the core material in polyvinyl chloride to obtain a cerium - based metal - organic framework core - shell structure modifier.

[0125] A preparation method of a nano - composite heat stabilizer specifically includes the following steps:

[0126] Mix 10 mL of tetrabutyl titanate and 30 mL of absolute ethanol to obtain solution A. Then mix 25 mL of absolute ethanol, 10 mL of deionized water and 20 mL of glacial acetic acid, add a nitric acid solution with a mass fraction of 65% dropwise to adjust the pH of the solution to ≤ 3, add silver nitrate and urea solids, stir evenly to obtain solution B. The addition amount of silver nitrate is 0.05 g, and the addition amount of urea is 0.3 g. The doping of silver ions can reduce the band gap width of titanium dioxide, and nitrogen elements can improve the electronic structure and surface properties of titanium dioxide, thereby enhancing its thermal stability and ultraviolet resistance. Under the action of a strong magnetic stirrer, slowly add solution A drop by drop to solution B to enable them to react fully. After the addition is completed, stir for 30 min to obtain a white transparent colloid, let it age for 24 h, dry it and then place it in a muffle furnace for calcination treatment. During the calcination process, first heat up to 350 °C, increase the temperature by 10 °C each time until it reaches 430 °C, then calcine for 200 min, cool down to room temperature, and grind. Using tetrabutyl titanate as the precursor source of titanium, silver nitrate as the source of Ag, and urea as the source of N, through the calcination process, N-Ag co-doped modified nano-titanium dioxide is obtained, effectively improving the thermal stability of nano-titanium dioxide. Doping modification is also beneficial to the dispersion of nano-titanium dioxide, enabling it to be evenly dispersed in the polyvinyl chloride matrix, significantly enhancing the strength, durability and anti-aging properties of the plastic, and obtaining a nano-composite heat stabilizer.

[0127] This example provides a method for preparing a high-strength and anti-aging soft plastic, which specifically includes the following steps:

[0128] S1. Put 2-propylheptanol liquid and adipic acid solid into a four-necked flask equipped with a stirrer, thermometer, condenser and water separator according to a molar ratio of 1:2.5, and add a titanate catalyst at 0.3% of the total mass of 2-propylheptanol and adipic acid. The titanate catalyst is tetrabutyl titanate. Tetrabutyl titanate is an efficient catalyst applied to various organic synthesis reactions, which can significantly reduce the reaction temperature, reduce the generation of by-products, improve the reaction efficiency and product purity. Start stirring, heat up to 180 °C to start water reflux, separate and collect the water carried out by 2-propylheptanol, and the alcohol refluxes to the flask to continue participating in the reaction. When the acid value of the reaction product reaches less than 0.2 mg / g in terms of potassium hydroxide, the reaction ends. Cool the reaction material to 90 °C, neutralize and wash it with a 5% sodium hydroxide solution, let it stand and separate to remove the aqueous phase, and subject the obtained crude ester to vacuum distillation, and then filter and decolorize it through activated carbon. The di(2-propylheptyl) adipate prepared by this process is a functional plasticizer, which broadens the scope of use, can improve the cold resistance of polyvinyl chloride plastics, reduce cracks and damage caused by low temperature, and is beneficial to the durability of plastic products, and a low-temperature resistant plasticizer is obtained;

[0129] S2. Mix the low-temperature resistant plasticizer, cerium-based metal framework core-shell structure modifier, nano-composite heat stabilizer, silica filler, calcium stearate, and polyvinyl chloride described in step S1 evenly at a mixing speed of 1000 rpm for 30 minutes. Then, put the mixed material into a twin-screw granulator for granulation. By adding the cerium-based metal framework core-shell structure modifier and nano-composite heat stabilizer, the mechanical properties and thermal stability of polyvinyl chloride are significantly enhanced, and a high-strength anti-aging soft plastic is obtained.

[0130] Comparative Example 1

[0131] This comparative example provides a high-strength anti-aging soft plastic, which is different from Example 1 in that the cerium-based metal framework core-shell structure modifier does not contain lignin liquefied product; the preparation method of the cerium-based metal framework core-shell structure modifier does not include steps (5) and (6); the preparation method of the nano-composite heat stabilizer is the same as that in Example 1; the preparation method of the high-strength anti-aging soft plastic is the same as that in Example 1.

[0132] Comparative Example 2

[0133] This comparative example provides a high-strength anti-aging soft plastic, which is different from Example 1 in that the nano-composite heat stabilizer does not contain silver nitrate and urea; the preparation method of the cerium-based metal framework core-shell structure modifier is the same as that in Example 1; in the preparation method of the nano-composite heat stabilizer, silver nitrate and urea are not added for doping modification; the preparation method of the high-strength anti-aging soft plastic is the same as that in Example 1.

[0134] Comparative Example 3

[0135] This comparative example provides a high-strength anti-aging soft plastic, which is different from Example 1 in that the high-strength anti-aging soft plastic does not contain the cerium-based metal framework core-shell structure modifier and nano-composite heat stabilizer; the preparation method of the high-strength anti-aging soft plastic is the same as that in Example 1.

[0136] Experimental Example 1

[0137] Mechanical Property Experiment

[0138] Test samples: The high-strength anti-aging soft plastics prepared in Examples 1-4 and Comparative Examples 1-3.

[0139] Test method: Conduct mechanical property tests on the test samples. Among them, the tensile strength is tested according to the method specified in GB / T1040-92, the flexural strength is tested according to the method specified in GB / T1936.1-1991, and the impact strength is tested according to the method specified in GB / T1043-93.

[0140] Figure 4Graph of mechanical property results for Examples 1-4 and Comparative Examples 1-3; As shown in the figure, the tensile strength, flexural strength and impact strength of Examples 1-4 are 62.0-65.8 MPa, 94.6-96.7 MPa, 38.5-40.3 KJ / m 2 , indicating relatively high strength; the tensile strength, flexural strength and impact strength of Comparative Examples 1-3 are 51.2-58.3 MPa, 85.2-89.4 MPa, 31.4-35.8 KJ / m 2 , indicating relatively low strength; the cerium-based metal framework core-shell structure modifier in Comparative Example 1 does not contain lignin liquefied product and cannot form a coating shell material, reducing the compatibility between the core material and the polyvinyl chloride matrix and restricting its improvement of the mechanical properties of polyvinyl chloride, resulting in relatively low strength; the nano-composite heat stabilizer in Comparative Example 2 does not contain silver nitrate and urea and cannot dope and modify nano-titanium dioxide, which is not conducive to the uniform dispersion of nano-titanium dioxide and restricts the improvement of the mechanical properties of polyvinyl chloride, resulting in relatively low strength; the high-strength anti-aging soft plastic in Comparative Example 3 does not contain a cerium-based metal framework core-shell structure modifier and a nano-composite heat stabilizer and cannot exert the improvement effect of the two levels of micron and nano modification substances on the mechanical properties of polyvinyl chloride, resulting in relatively low strength.

[0141] Experimental Example 2

[0142] Anti-aging experiment

[0143] Test samples: High-strength anti-aging soft plastics prepared in Examples 1-4 and Comparative Examples 1-3.

[0144] Test method: The test samples were subjected to an artificial accelerated aging experiment (90 °C, 500 h) according to the thermal oxygen aging experiment standard GB / T7141-2008.

[0145] Figure 5Graph showing the anti-aging results of Examples 1-4 and Comparative Examples 1-3; as shown in the figure, the tensile strength retention rates and impact strength retention rates of Examples 1-4 are 87.6 - 89.5% and 86.7 - 88.6% respectively, indicating good anti-aging performance; the tensile strength retention rates and impact strength retention rates of Comparative Examples 1-3 are 75.2 - 84.5% and 74.3 - 83.2% respectively, indicating poor anti-aging performance; the cerium-based metal framework core-shell structure modifier in Comparative Example 1 does not contain lignin liquefied product, which can neither exert the anti-aging effect of lignin liquefied product nor play the role of a compatibilizer, restricting the enhancement effect of the core substance on the thermal stability of polyvinyl chloride and resulting in poor anti-aging performance; the nano-composite heat stabilizer in Comparative Example 2 does not contain silver nitrate and urea, and cannot form N-Ag co-doped modified nano-titanium dioxide, which is not conducive to improving the thermal stability of nano-titanium dioxide and leads to poor anti-aging performance; the high-strength anti-aging soft plastic in Comparative Example 3 does not contain cerium-based metal framework core-shell structure modifier and nano-composite heat stabilizer, and cannot synergistically improve the heat resistance of polyvinyl chloride, resulting in poor anti-aging performance.

[0146] The above experimental results show that the mechanical properties and anti-aging properties of Examples 1-4 of the present invention are significantly better than those of the samples of Comparative Examples 1-3. Among them, Example 1 using a cerium-based metal framework core-shell structure modifier and a nano-composite heat stabilizer has higher strength and better anti-aging performance. With a cerium-based metal framework and carboxylated graphene oxide as the core substances and lignin liquefied product as the shell substance, a core-shell structure coating is formed. The lignin liquefied product can enhance the strength and thermal stability of polyvinyl chloride and can also act as a compatibilizer, enabling the core substances to be well dispersed in the polyvinyl chloride matrix, thus better exerting the synergistic effect of the cerium-based metal framework and carboxylated graphene oxide in enhancing the strength and anti-aging properties of polyvinyl chloride plastics. The nano-composite heat stabilizer is a N-Ag co-doped modified nano-titanium dioxide, which improves the thermal stability and anti-ultraviolet performance of nano-titanium dioxide, is also conducive to the dispersion of nano-titanium dioxide, enables it to be evenly dispersed in the polyvinyl chloride matrix, is beneficial to improving the strength and anti-aging of plastics, and has better durability.

[0147] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made in these embodiments without departing from the principles and spirit of the present invention.

[0148] The above describes the present invention and its embodiments, and this description is not restrictive. What is shown in the drawings is only one of the embodiments of the present invention, and the actual application is not limited thereto. In short, if those of ordinary skill in the art are inspired by it and, without departing from the purpose of the present invention, design similar methods and embodiments to this technical solution without creative efforts, they shall fall within the protection scope of the present invention.

Claims

1. A high-strength, anti-aging soft plastic, characterized by: The high-strength anti-aging soft plastic comprises the following components in parts by weight: 10-15 parts of a cerium-based metal framework core-shell structure modifier, 15-25 parts of a nano-composite heat stabilizer, 30-40 parts of a low-temperature resistant plasticizer, 20-25 parts of a silicon dioxide filler, 2-5 parts of calcium stearate, and 90-100 parts of polyvinyl chloride; the cerium-based metal framework core-shell structure modifier comprises the following components in parts by weight: 10-20 parts of a cerium-based metal framework, 10-20 parts of carboxylated graphene oxide, and 10-20 parts of lignin liquefied product; the nano-composite heat stabilizer is a nano-titanium dioxide composite modified by N-Ag co-doping; and the low-temperature resistant plasticizer is di(2-propylheptyl) adipate synthesized using 2-propylheptyl alcohol and adipic acid as raw materials.

2. A method for preparing the high-strength anti-aging soft plastic according to claim 1, characterized in that: The specific steps include: S1, 2-propyl heptanol liquid, adipic acid solid according to the ratio of 1:2.5 molar ratio into a four-necked flask equipped with a stirrer, a thermometer, a condenser and a water separator, according to 0.3% of the total mass of 2-propyl heptanol and adipic acid, add a titanate catalyst, start stirring, heat to 180 ° C to start water reflux, separate and collect the water taken out by 2-propyl heptanol, alcohol refluxes to the flask to continue to participate in the reaction, the acid value of the reaction product reaches 0.2mg / g or less when the reaction is completed, the reaction mass is cooled to 90 ° C, and the mass fraction of 5% sodium hydroxide solution is neutralized and washed with water, and the aqueous phase is removed by standing and stratification, and the obtained crude ester is distilled under reduced pressure, and then filtered and decolorized by activated carbon to obtain a low temperature resistant plasticizer; S2. Evenly mix the low-temperature resistant plasticizer described in step S1, the cerium-based metal framework core-shell structure modifier, the nano-composite thermal stabilizer, the silica filler, the calcium stearate, and the polyvinyl chloride, at a mixing speed of 600-1000 rpm and a mixing time of 30-50 min, and then put the mixture into a twin-screw granulator for granulation to obtain a high-strength and anti-aging soft plastic.

3. The method for preparing high-strength anti-aging soft plastic according to claim 2, characterized in that: In step S1, the titanate catalyst is tetrabutyl titanate.

4. The method for preparing high-strength anti-aging soft plastic according to claim 3, characterized in that: The preparation method of the cerium-based metal framework core-shell structure modifier specifically comprises the following steps: (1) Dissolve 0.5-0.6 g of ammonium cerium nitrate powder in 15 mL of deionized water, and dissolve 0.2 g of terephthalic acid powder in 30 mL of N,N-dimethylformamide. Then, mix the two solutions and stir for 3 minutes. The resulting mixed solution is placed in a reaction kettle, heated at 100-110° C. for 20-30 minutes, cooled to 25° C., and centrifuged to obtain a separated product. The product is then washed 3-5 times with 50 mL of N,N-dimethylformamide and 50 mL of deionized water, respectively, to fully remove unreacted terephthalic acid, and dried to obtain a cerium-based metal framework. (2) 2.0 g of graphite powder, 50 mL of 90-96% sulfuric acid solution, and 0.6-1.0 g of sodium nitrate powder were placed in a round-bottom flask. Under stirring in an ice bath, 6.0-8.0 g of potassium permanganate powder were slowly added. The reaction system was then placed in a 30-35°C water bath and stirred for 1 h at a stirring speed of 1000-3000 rpm. Then, 100 mL of water, 10 mL of 20-30% hydrogen peroxide liquid, and 300 mL of water were slowly added in sequence. The mixture was allowed to stand at 25°C overnight, then washed until neutral, and ultrasonically filtered to obtain a graphene oxide suspension. (3) adding sodium hydroxide powder and chloroacetic acid powder to 30-50 mL of the graphene oxide suspension described in step (2), ultrasonically treating for 2-3 h at an ultrasonic power of 600-800 W, then filtering, evaporating, and drying to obtain carboxylated graphene oxide; (4) dissolving the carboxylated graphene oxide described in step (3) in N,N-dimethylformamide, adding the cerium-based metal framework described in step (1), heating the reaction for 10-12 hours, and controlling the temperature to be 100-120° C. to obtain a cerium-based metal framework composite core; (5) Place the lignin in a 120°C oven for dehydration and drying for 120 min, weigh 6.0 g of the treated lignin, 24.0 g of polyethylene glycol-600 and 6.0 g of propylene glycol and place them in a round-bottom flask. After fully stirring on a constant temperature magnetic stirrer, use a pipette to pipette 0.5 mL of a 98% sulfuric acid solution and drip it in. Continue stirring for 30 min. Transfer the round-bottom flask to a microwave synthesis extractor. After the lignin liquefaction is completed, naturally cool it to 70°C, vacuum filter it to remove the residual solids, and dry the filtrate to obtain a lignin liquefied product. (6) The cerium-based metal framework composite core material described in step (4) and the lignin liquefied material described in step (5) are weighed in a mass ratio of 2:1 and placed in a ball mill. Grinding balls with a diameter of 4 mm are added, and the ball-to-material mass ratio is 40:

1. The ball mill speed is 300-400 rpm, and the forward and reverse rotations are performed for 2 hours each to allow a mechanochemical reaction to occur, thereby obtaining a cerium-based metal framework core-shell structure modifier.

5. The method for preparing high-strength anti-aging soft plastic according to claim 4, characterized in that: In step (3), the amount of sodium hydroxide added is 5.0-6.0 g, and the amount of chloroacetic acid added is 4.0-5.0 g.

6. The method for preparing high-strength anti-aging soft plastic according to claim 5, characterized in that: In step (5), during the microwave synthesis extraction process, the power is controlled at 500-600 W, the reaction temperature is 140-160° C., and the reaction time is 10-20 min.

7. The method for preparing high-strength anti-aging soft plastic according to claim 6, characterized in that: The preparation method of the nanocomposite thermal stabilizer specifically comprises the following steps: 10 mL of tetrabutyl titanate and 30-40 mL of anhydrous ethanol were mixed to obtain solution A, and then 25-35 mL of anhydrous ethanol, 10 mL of deionized water and 20 mL of glacial acetic acid were mixed, and a nitric acid solution with a mass fraction of 65% was added dropwise to adjust the pH of the solution to ≤ 3, and silver nitrate and urea solid were added, and the mixture was stirred evenly to obtain solution B. Under the action of a strong magnetic stirrer, solution A was slowly added dropwise to solution B to enable it to react fully. After the addition was completed, the mixture was stirred for 30 minutes to obtain a white transparent colloid, which was placed for aging for 24 hours, dried, and then placed in a muffle furnace for calcination. During the calcination process, the temperature was raised to 350°C for the first time, and the temperature was increased by 10°C each time until the temperature reached 430°C, and then calcined for 200 minutes, cooled to room temperature, and ground to obtain a nano-composite thermal stabilizer.

8. The method for preparing high-strength anti-aging soft plastic according to claim 7, characterized in that: The amount of silver nitrate added is 0.05-0.1g, and the amount of urea added is 0.3-0.5g.

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