Environment-friendly degradable plastic bottle and preparation method thereof

Abstract

The present application belongs to the technical field of degradable plastic packaging, and particularly relates to an environment-friendly degradable plastic bottle and a preparation method thereof. The environment-friendly degradable plastic bottle comprises the following raw materials in parts by weight: polybutylene succinate 60-85 parts, polylactic acid 10-30 parts, a compatilizer 2-5 parts, nano-clay 1-5 parts, tetrahydrocurcumin multi-effect stabilizer 1-3 parts, and a lubricant 0.1-0.5 parts. By adding the tetrahydrocurcumin multi-effect stabilizer and the nano-clay to the PBS / PLA blending system, the synergistic effect of the two is utilized, so that the plastic bottle of the present application has excellent barrier properties, good mechanical strength and excellent ultraviolet aging resistance, and retains the environment-friendly properties of degradable plastics, and is particularly suitable for pesticide packaging and other application scenarios with high requirements for barrier properties and durability.

Description

Technical Field

[0001] This invention belongs to the field of biodegradable plastic packaging technology, specifically relating to an environmentally friendly biodegradable plastic bottle and its preparation method. Background Technology

[0002] Plastic products are widely used in various industries due to their advantages such as being lightweight, durable, and inexpensive. However, traditional plastics such as polyethylene, polypropylene, and polyethylene terephthalate are difficult to degrade in the natural environment, causing serious "white pollution." Pesticide packaging bottles are one of the important application areas of plastic products. For a long time, pesticide bottles have mostly been made of traditional plastics such as high-density polyethylene (HDPE) and polypropylene (PP). Although they have excellent mechanical and processing properties, they are not degradable and become a significant source of pollution in rural areas after being discarded. With increasingly stringent environmental protection requirements, the development of biodegradable pesticide packaging bottles has become an urgent need for the industry.

[0003] Polylactic acid (PLA) and polybutylene succinate (PBS) are mainstream biodegradable polyesters. PLA has high strength and good transparency, but poor toughness, slow crystallization, and insufficient impact resistance; PBS has excellent flexibility and processability, and can improve the brittleness of PLA, but its strength and modulus are relatively low. Simple blending of the two has problems such as thermodynamic incompatibility, weak interfacial bonding, insufficient barrier properties, poor UV resistance, and easy degradation during processing. In the prior art, CN114702775A discloses a PLA / PBS composite barrier material, but this patent does not solve the problems of organic solvent resistance and UV resistance of the material; CN116285243A discloses a biodegradable pesticide bottle using a PLA / PBAT / PPC / PGA system, which also does not involve long-term UV resistance and high pesticide solvent resistance modification; CN112812419A, CN114350050A, etc., use polyethylene substrate + barrier filler, and none of them can be completely biodegradable.

[0004] Currently, biodegradable pesticide bottles still face three major technical bottlenecks: (1) Insufficient barrier properties, pesticide organic solvents such as xylene and esters can easily penetrate, leading to pesticide leakage and failure; (2) Poor resistance to ultraviolet aging: PLA and PBS are sensitive to ultraviolet light and are prone to yellowing and cracking; (3) Poor processing stability: traditional small molecule adjuvants are prone to migration and have poor solvent resistance.

[0005] Therefore, developing a biodegradable plastic bottle that combines high barrier properties, high resistance to UV aging, excellent mechanical properties, and processing stability, especially suitable for pesticide packaging, is of great practical significance. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide an environmentally friendly biodegradable plastic bottle and its preparation method.

[0007] The objective of this invention is achieved through the following technical solution: An environmentally friendly biodegradable plastic bottle comprises the following raw materials in parts by weight: 60-85 parts polybutylene succinate, 10-30 parts polylactic acid, 2-5 parts compatibilizer, 1-5 parts nano clay, 1-3 parts tetrahydrocurcumin multi-effect stabilizer, and 0.1-0.5 parts lubricant. The structural formula of the tetrahydrocurcumin multi-effect stabilizer is as follows: .

[0008] Furthermore, the nano-clay includes, but is not limited to, kaolinite, montmorillonite, organosilicon bentonite, vermiculite, and synthetic layered silicates. Through the compounding of the above raw materials, the resulting plastic bottle possesses excellent barrier properties, biodegradability, mechanical properties, and processing stability, while maintaining controllable costs.

[0009] Furthermore, the preparation process of the tetrahydrocurcumin multi-effect stabilizer is as follows: (1) In the presence of formaldehyde, tetrahydrocurcumin was reacted with 4-amino-2,2,6,6-tetramethylpiperidine under reflux in ethanol to obtain intermediate 1; the structural formula of intermediate 1 is as follows: This step can introduce the hindered amine photostable fragment into the tetrahydrocurcumin skeleton, providing a reaction site for subsequent multifunctional modification. (2) In the presence of a quaternary ammonium salt phase transfer catalyst, intermediate 1 is added to epichlorohydrin to carry out a ring-opening reaction, followed by a ring-closing reaction under the action of a strong base to obtain intermediate 2; the structural formula of intermediate 2 is as follows: This step introduces epoxy active groups into the molecule, which facilitates the subsequent grafting of long-chain fatty acids. (3) In the presence of an organophosphorus catalyst, intermediate 2 is subjected to a ring-opening grafting reaction with stearic acid in toluene to obtain intermediate 3; the structural formula of intermediate 3 is as follows: This step grafts long stearic acid chains into the molecule, which can significantly improve the compatibility of the stabilizer with the polyester matrix and prevent migration and precipitation during processing or use. (4) Under vacuum degree ≤ -0.09 MPa, intermediate 3 is subjected to transesterification reaction with diphenyl phosphite to obtain the tetrahydrocurcumin multi-effect stabilizer; this step introduces phosphite antioxidant groups into the molecule, thereby endowing the material with excellent thermal processing stability and long-term antioxidant aging performance.

[0010] Furthermore, in step (1), the molar ratio of tetrahydrocurcumin, 4-amino-2,2,6,6-tetramethylpiperidine, and formaldehyde is 1:(2.2-2.5):(2.2-2.5); the reflux reaction time is 5-6 h. This molar ratio and reaction time ensure that the hindered amine group is fully substituted, and the yield can reach over 85%.

[0011] Further, in step (2), the quaternary ammonium salt phase transfer catalyst is tetrabutylammonium bromide; the strong base is sodium hydroxide; the molar ratio of intermediate 1, epichlorohydrin, quaternary ammonium salt phase transfer catalyst, and strong base is 1:(10-15):(0.05-0.06):(2.2-2.4); the ring-opening reaction temperature is 60-70℃, and the time is 2-3 h; the ring-closing reaction temperature is 70-75℃, and the time is 4-5 h. These conditions enable efficient formation of epoxy groups, with a yield of not less than 80% and few byproducts.

[0012] Furthermore, the organophosphorus catalyst in step (3) is triphenylphosphine; the molar ratio of intermediate 2, stearic acid, and organophosphorus catalyst is 1:(2-2.1):(0.01-0.02); the ring-opening grafting reaction is carried out at a temperature of 110-120℃ for 6-8 h. Under these conditions, the grafting rate can reach over 90%, and the stearic acid is almost completely reacted.

[0013] Furthermore, in step (4), the molar ratio of intermediate 3 to diphenyl phosphite is 1:(2-2.2); the transesterification reaction is carried out at a temperature of 130-140℃ for 4-5 hours. This step is performed under vacuum conditions, which allows for timely removal of phenol, promotes reaction equilibrium, and achieves a product purity of over 95%.

[0014] Furthermore, the compatibilizer is maleic anhydride-grafted polybutylene succinate; the lubricant is calcium stearate. This invention utilizes maleic anhydride-grafted PBS as a compatibilizer to effectively improve the interfacial compatibility between PBS and PLA, while calcium stearate combines lubrication and acid absorption functions, preventing processing degradation.

[0015] Furthermore, the weight-average molecular weight of the polybutylene succinate is 80,000-200,000 Da; the weight-average molecular weight of the polylactic acid is 100,000-300,000 Da; the grafting rate of the maleic anhydride-grafted PBS is 1-3%, and the melt index (MI) under the test conditions of 190℃ and 2.16 kg is 1-10 g / 10 min. The above molecular weight range ensures the mechanical strength and processing fluidity of the matrix resin, and the grafting rate and melt index of the compatibilizer are also matched with the matrix, which is beneficial for filler dispersion and interfacial bonding.

[0016] A second aspect of the present invention provides a method for preparing the environmentally friendly biodegradable plastic bottle described in the first aspect above, comprising the following steps: (a) According to the stated weight proportions, after drying polybutylene succinate and polylactic acid, they are mixed evenly with tetrahydrocurcumin multi-effect stabilizer, nano clay, compatibilizer and lubricant to obtain a mixture; (b) The mixture is melt-extruded and granulated to obtain modified particles; (c) The modified particles are injection blow molded to obtain an environmentally friendly biodegradable plastic bottle.

[0017] Furthermore, in step (b), the melt extrusion is performed using a twin-screw extruder with an extrusion temperature of 150-180℃ and a screw speed of 200-400 rpm.

[0018] Further, the injection blow molding in step (c) includes: injection molding a preform at 180-190°C, and then blow molding at 90-110°C with a blow molding pressure of 0.5-1.0 MPa.

[0019] The present invention has the following advantages over the prior art: 1. This invention adds tetrahydrocurcumin multi-effect stabilizer and nano-clay to the PBS / PLA blend system. By utilizing the synergistic effect of the two, the plastic bottle of this invention simultaneously possesses excellent barrier properties, good mechanical strength and outstanding anti-UV aging properties, while retaining the environmentally friendly properties of biodegradable plastics. It is particularly suitable for applications such as pesticide packaging that have high requirements for barrier properties and durability.

[0020] 2. This invention significantly improves the UV aging resistance, thermal stability, and mechanical properties of the PBS / PLA blend system by introducing a tetrahydrocurcumin multi-effect stabilizer. The tetrahydrocurcumin skeleton does not contain conjugated double bonds, exhibiting superior thermal stability compared to curcumin, thus enabling it to withstand processing temperatures. The tetrahydrocurcumin multi-effect stabilizer of this invention contains a hindered amine structure, which can efficiently capture UV-induced free radicals, inhibit photo-oxidative chain scission of the polymer molecular chain, and improve the material's UV aging resistance. Furthermore, this hindered amine structure can form a phosphorus-nitrogen synergistic antioxidant system with the phosphite in the molecule, inhibiting the thermal oxidative degradation of the polymer matrix during high-temperature processing and maintaining the integrity of the molecular chain. Simultaneously, the long carbon chain of stearic acid in the molecule can improve the compatibility between the stabilizer and the PBS / PLA matrix, improving the interfacial bonding between the two phases, thereby maintaining the material's mechanical properties.

[0021] 3. This invention significantly improves the barrier properties of plastic bottles by introducing nano-clay into a PBS / PLA blend system. After the layered structure of the nano-clay is uniformly dispersed in the polymer matrix, it forms a "maze effect," preventing gas and solvent molecules from penetrating the bottle wall in a straight line. Instead, they must bypass the nano-clay layers, thus lengthening the diffusion path and reducing permeability. Detailed Implementation

[0022] The technical solution of the present invention will be further described below with reference to specific embodiments. However, those skilled in the art should understand that the following embodiments are only for illustrating the present invention and should not be regarded as limiting the present invention. Specific conditions not specified in the embodiments are performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the reagents or instruments used are all conventional products obtained through commercial channels.

[0023] In the following examples and comparative examples, the weight-average molecular weight of PBS was 120,000 Da; the weight-average molecular weight of PLA was 200,000 Da; the grafting rate of maleic anhydride-grafted PBS was 1-3%, and the melt index (MI) under the test conditions of 190°C and 2.16 kg was 1-10 g / 10 min; the nanoclay was organosilicon bentonite with a particle size of 20-100 nm.

[0024] Example 1 A tetrahydrocurcumin multi-effect stabilizer, the preparation process of which is as follows: (1) Dissolve tetrahydrocurcumin (10 mmol) in anhydrous ethanol (18 mL), add 4-amino-2,2,6,6-tetramethylpiperidine (23 mmol), stir until homogeneous, heat to 45 °C, slowly add 37% formaldehyde solution (23 mmol) dropwise, heat to reflux after the addition is complete, and stir for 6 h. After the reaction is complete, cool to room temperature, remove solvent by vacuum evaporation, wash the crude product three times with deionized water to remove unreacted amine and formaldehyde, and dry under vacuum to obtain intermediate 1 with a yield of about 90.4%. 1 H NMR (C 41 H 64 N4O6, 400 MHz, DMSO): δ 9.59 (s, 2H), 6.71 (s, 2H), 6.56(s, 2H), 4.20 (s, 2H), 3.86 (s, 6H), 3.76 (s, 4H), 3.61 (s, 2H), 2.82-2.78(m, 8H), 2.65-2.61 (m, 2H), 2.05 (s, 2H), 1.60-1.56 (m, 4H), 1.35-1.31 (m,4H), 1.22 (s, 24H); HRMS(ESI + ): [M+H] + The calculation yields 709.48, and the result is 709.49.

[0025] (2) Intermediate 1 (10 mmol) was dissolved in epichlorohydrin (120 mmol), tetrabutylammonium bromide (0.55 mmol) was added, the temperature was raised to 65 °C, and the mixture was stirred for 2 h. Then, powdered sodium hydroxide (23 mmol) was added in batches, and the mixture was stirred at 70 °C for 5 h. After the reaction was completed, the inorganic salt was removed by filtration, and the excess epichlorohydrin was recovered by vacuum distillation of the filtrate. The residue was dissolved in dichloromethane, washed with water until neutral, dried over anhydrous magnesium sulfate, and concentrated to obtain intermediate 2 with a yield of about 85.0%. 1 H NMR (C 47 H 72 N4O8, 400 MHz, DMSO): δ 6.71 (s, 2H), 6.56 (s, 2H), 4.20-4.16 (m, 4H), 3.96-3.92 (m, 2H), 3.86 (s, 6H), 3.76 (s, 4H), 3.61 (s, 2H), 3.05-3.02 (m,2H), 2.82-2.78 (m, 8H), 2.65-2.61 (m, 4H), 2.38-2.35 (m, 2H), 2.05 (s, 2H),1.60-1.56 (m, 4H), 1.35-1.31 (m, 4H), 1.22 (s, 24H) ; HRMS(ESI + ): [M+H] + The calculation yields 821.54, and the value is found to be 821.54.

[0026] (3) Intermediate 2 (10 mmol) and stearic acid (20 mmol) were added to toluene (18 mL), followed by triphenylphosphine (0.12 mmol). The mixture was heated to 115 °C and stirred for 7 h. After the reaction was completed, the mixture was cooled to room temperature and washed successively with 5% sodium carbonate solution and hot saturated brine. The organic layer was dried with anhydrous sodium sulfate and the solvent was removed by vacuum evaporation to obtain intermediate 3 with a yield of about 92.0%. 1 H NMR (C 83 H 144 N4O 12, 400 MHz, DMSO): δ 6.91 (s, 2H), 6.76 (s, 2H), 5.77(s, 2H), 4.71-4.68 (m, 2H), 4.35-4.33 (m, 2H), 4.20-4.16 (m, 4H), 4.08-3.95(m, 4H), 3.86 (s, 6H), 3.76 (s, 4H), 3.61 (s, 2H), 2.82-2.78 (m, 8H), 2.65-2.61 (m, 2H), 2.32(t, 4H), 2.05 (s, 2H), 1.66-1.60 (m, 8H), 1.35-1.22 (s,84H), 0.88(t, 6H); HRMS(ESI + ): [M+H] + The calculation yields 1390.08, and the value is found to be 1390.08.

[0027] (4) Intermediate 3 (10 mmol) and diphenyl phosphite (21 mmol) were added to a three-necked flask and heated to 135°C under nitrogen protection. The vacuum pump was turned on and the mixture was stirred for 4 h under a vacuum of ≤-0.09 MPa. The byproduct phenol generated during the reaction was continuously removed using a vacuum device. After the reaction was completed, the material was cooled to about 80°C, a small amount of anhydrous ethanol was added for washing and the mixture was dried under vacuum to obtain the final product tetrahydrocurcumin multi-effect stabilizer with a yield of about 86.0%. 1 H NMR (C 107 H 162 N4O 18 P2, 400MHz, DMSO): δ 7.28-7.17(m, 20H), 6.91 (s, 2H), 6.76 (s, 2H), 5.27-5.23 (m,2H), 4.53-4.50 (m, 2H), 4.40-4.36 (m, 2H), 4.28-4.25 (m, 2H), 4.16-4,13 (m,4H), 3.86 (s, 6H), 3.76 (s, 4H), 3.61 (s, 2H), 2.82-2.78 (m, 8H), 2.65-2.61(m, 2H), 2.32(t, 4H), 2.05 (s, 2H), 1.66-1.60 (m, 8H), 1.35-1.22 (s, 84H),0.88(t, 6H); HRMS(ESI + ): [M+H] + The calculation yields 1854.14, and the value is found to be 1854.14.

[0028] Example 2 A tetrahydrocurcumin multi-effect stabilizer, the preparation process of which is as follows: (1) Dissolve tetrahydrocurcumin (10 mmol) in anhydrous ethanol (15 mL), add 4-amino-2,2,6,6-tetramethylpiperidine (22 mmol), stir until homogeneous, heat to 40 °C, slowly add 37% formaldehyde solution (22 mmol) dropwise, heat to reflux after addition, and stir for 5 h; after the reaction is complete, cool to room temperature, remove solvent by vacuum distillation, wash the crude product three times with deionized water to remove unreacted amine and formaldehyde, dry under vacuum to obtain intermediate 1, with a yield of about 89.1%.

[0029] (2) Intermediate 1 (10 mmol) was dissolved in epichlorohydrin (100 mmol), tetrabutylammonium bromide (0.5 mmol) was added, the temperature was raised to 60 °C, and the mixture was stirred for 3 h. Then, powdered sodium hydroxide (22 mmol) was added in batches, and the mixture was stirred at 70 °C for 5 h. After the reaction was completed, the inorganic salt was removed by filtration, and the excess epichlorohydrin was recovered by vacuum distillation of the filtrate. The residue was dissolved in dichloromethane, washed with water until neutral, dried over anhydrous magnesium sulfate, and concentrated to obtain intermediate 2 with a yield of about 83.6%.

[0030] (3) Intermediate 2 (10 mmol) and stearic acid (20 mmol) were added to toluene (15 mL), followed by triphenylphosphine (0.1 mmol). The mixture was heated to 110 °C and stirred for 8 h. After the reaction was completed, the mixture was cooled to room temperature and washed successively with 5% sodium carbonate solution and hot saturated brine. The organic layer was dried with anhydrous sodium sulfate and the solvent was removed by vacuum evaporation to obtain intermediate 3 with a yield of about 91.4%.

[0031] (4) Intermediate 3 (10 mmol) and diphenyl phosphite (20 mmol) were added to a three-necked flask and heated to 130°C under nitrogen protection. The vacuum pump was turned on and the reaction was stirred for 5 h under a vacuum of ≤-0.09 MPa. The byproduct phenol generated by the reaction was continuously removed using a vacuum device. After the reaction was completed, the material was cooled to about 80°C, a small amount of anhydrous ethanol was added for washing and the mixture was dried under vacuum to obtain the final product tetrahydrocurcumin multi-effect stabilizer with a yield of about 85.5%.

[0032] Example 3 A tetrahydrocurcumin multi-effect stabilizer, the preparation process of which is as follows: (1) Dissolve tetrahydrocurcumin (10 mmol) in anhydrous ethanol (20 mL), add 4-amino-2,2,6,6-tetramethylpiperidine (25 mmol), stir until homogeneous, heat to 50 °C, slowly add 37% formaldehyde solution (25 mmol) dropwise, heat to reflux after the addition is complete, and stir for 5 h; after the reaction is complete, cool to room temperature, remove solvent by vacuum evaporation, wash the crude product three times with deionized water to remove unreacted amine and formaldehyde, dry under vacuum to obtain intermediate 1, with a yield of about 88.5%.

[0033] (2) Intermediate 1 (10 mmol) was dissolved in epichlorohydrin (150 mmol), tetrabutylammonium bromide (0.6 mmol) was added, the temperature was raised to 70 °C, and the mixture was stirred for 2 h. Then, powdered sodium hydroxide (24 mmol) was added in batches, and the mixture was stirred at 75 °C for 4 h. After the reaction was completed, the inorganic salt was removed by filtration, and the excess epichlorohydrin was recovered by vacuum distillation of the filtrate. The residue was dissolved in dichloromethane, washed with water until neutral, dried over anhydrous magnesium sulfate, and concentrated to obtain intermediate 2 with a yield of about 82.9%.

[0034] (3) Intermediate 2 (10 mmol) and stearic acid (21 mmol) were added to toluene (20 mL), followed by triphenylphosphine (0.2 mmol). The mixture was heated to 120 °C and stirred for 6 h. After the reaction was completed, the mixture was cooled to room temperature and washed successively with 5% sodium carbonate solution and hot saturated brine. The organic layer was dried with anhydrous sodium sulfate and the solvent was removed by vacuum evaporation to obtain intermediate 3 with a yield of about 90.5%.

[0035] (4) Intermediate 3 (10 mmol) and diphenyl phosphite (22 mmol) were added to a three-necked flask and heated to 140°C under nitrogen protection. The vacuum pump was turned on and the reaction was stirred for 4 h under a vacuum of ≤-0.09 MPa. The byproduct phenol generated by the reaction was continuously removed using a vacuum device. After the reaction was completed, the material was cooled to about 80°C, a small amount of anhydrous ethanol was added for washing and the mixture was dried under vacuum to obtain the final product tetrahydrocurcumin multi-effect stabilizer with a yield of about 84.9%.

[0036] Example 4 An environmentally friendly biodegradable plastic bottle comprises the following raw materials in parts by weight: 72 parts polybutylene succinate, 22 parts polylactic acid, 4 parts compatibilizer, 3 parts nano clay, 2 parts tetrahydrocurcumin multi-effect stabilizer, and 0.2 parts lubricant.

[0037] This embodiment also provides a method for preparing the above-mentioned environmentally friendly biodegradable plastic bottle, including the following steps: (a) Polybutylene succinate (PBS) and polylactic acid (PLA) were vacuum dried at 80°C for 7 h to reduce their moisture content to less than 0.02%; the dried PBS and PLA resins were then added to a high-speed mixer along with tetrahydrocurcumin multi-effect stabilizer, nano clay, compatibilizer, and calcium stearate, and mixed at room temperature for 8 min to obtain a mixture. (b) The mixture is added to a co-rotating twin-screw extruder for melt extrusion granulation. The temperatures of each section of the extruder are set as follows: solid conveying section 150-160℃, melting section 170-185℃, and die head area 170-180℃. The screw speed is controlled at 300 rpm. After the extruded strip is cooled in a water tank and air-dried, it is fed into a pelletizer for granulation to obtain modified plastic particles. (c) The modified plastic particles are fed into an injection molding machine and injection molded into a bottle preform at 190°C. The bottle preform is reheated to 100°C and sent into a blow molding mold. Clean compressed air of 0.8 MPa is introduced to inflate the preform so that it adheres tightly to the inner wall of the mold. After cooling and solidification, the preform is demolded to obtain an environmentally friendly biodegradable plastic bottle.

[0038] Example 5 An environmentally friendly biodegradable plastic bottle comprises the following raw materials in parts by weight: 60 parts polybutylene succinate, 10 parts polylactic acid, 2 parts compatibilizer, 1 part nano clay, 1 part tetrahydrocurcumin multi-effect stabilizer, and 0.1 parts lubricant.

[0039] This embodiment also provides a method for preparing the above-mentioned environmentally friendly biodegradable plastic bottle, including the following steps: (a) Polybutylene succinate and polylactic acid were vacuum dried at 80°C for 6 h to reduce their moisture content to less than 0.02%; the dried PBS, PLA resin, tetrahydrocurcumin multi-effect stabilizer, nano clay, compatibilizer, and calcium stearate were added into a high-speed mixer and mixed at room temperature for 5 min to obtain a mixture. (b) The mixture is added to a co-rotating twin-screw extruder for melt extrusion granulation. The temperatures of each section of the extruder are set as follows: solid conveying section 150-160℃, melting section 170-185℃, and die head area 170-180℃. The screw speed is controlled at 200 rpm. After the extruded strip is cooled in a water tank and air-dried, it is fed into a pelletizer for granulation to obtain modified plastic particles. (c) The modified plastic particles are fed into an injection molding machine and injection molded into a bottle preform at 180°C; the bottle preform is reheated to 110°C and sent into a blow molding mold. Clean compressed air of 0.5 MPa is introduced to inflate the preform so that it adheres tightly to the inner wall of the mold. After cooling and solidification, the preform is demolded to obtain an environmentally friendly biodegradable plastic bottle.

[0040] Example 6 An environmentally friendly biodegradable plastic bottle comprises the following raw materials in parts by weight: 85 parts polybutylene succinate, 30 parts polylactic acid, 5 parts compatibilizer, 5 parts nano clay, 3 parts tetrahydrocurcumin multi-effect stabilizer, and 0.5 parts lubricant.

[0041] This embodiment also provides a method for preparing the above-mentioned environmentally friendly biodegradable plastic bottle, including the following steps: (a) Polybutylene succinate and polylactic acid were vacuum dried at 80°C for 8 h to reduce their moisture content to less than 0.02%; the dried PBS, PLA resin, tetrahydrocurcumin multi-effect stabilizer, nano clay, compatibilizer, and calcium stearate were added into a high-speed mixer and mixed at room temperature for 10 min to obtain a mixture. (b) The mixture is added to a co-rotating twin-screw extruder for melt extrusion granulation. The temperatures of each section of the extruder are set as follows: solid conveying section 150-160℃, melting section 170-185℃, and die head area 170-180℃. The screw speed is controlled at 400 rpm. After the extruded strip is cooled in a water tank and air-dried, it is fed into a pelletizer for granulation to obtain modified plastic particles. (c) The modified plastic particles are fed into an injection molding machine and injection molded into a bottle preform at 190°C. The bottle preform is reheated to 90°C and sent into a blow molding mold. Clean compressed air of 1.0 MPa is introduced to inflate the preform so that it adheres tightly to the inner wall of the mold. After cooling and solidification, the preform is demolded to obtain an environmentally friendly biodegradable plastic bottle.

[0042] Comparative Example 1 Comparative Example 1 is basically the same as Example 4, except that nano-clay is omitted.

[0043] Comparative Example 2 Comparative Example 2 is basically the same as Example 4, except that tetrahydrocurcumin multi-effect stabilizer is omitted.

[0044] Performance testing The plastic bottles obtained in Examples 4-6 and Comparative Examples 1-2 were subjected to the following performance tests.

[0045] (1) Barrier performance test Oxygen transmission rate: The oxygen transmission rate was measured using an oxygen transmission rate tester in accordance with GB / T 1038.1-2022 standard. A circular sample with a diameter of 100 mm was cut from the middle of the plastic bottle. The test conditions were 23±2℃ and relative humidity of 50±5%. The average value of 3 samples in each group was taken.

[0046] Water vapor transmission coefficient: determined by the cup weight gain method according to GB / T 1037-2021 standard. The test conditions were 38±1℃ and relative humidity 90±2%, and the average value of 3 samples in each group was taken.

[0047] Xylene permeation: The test was conducted according to the specifications and methods of ASTM D2684 / D2684M-2015. Xylene (purity ≥99%) was filled into a plastic bottle to 1 / 2 of its volume, sealed, and weighed (m1). The bottle was then placed at 50±2℃ for 14 days, removed, and weighed again (m2). The permeation was calculated using the formula: Permeation = m1 - m2. Three samples were tested for each group of samples, and the average value was taken.

[0048] (2) Mechanical property testing Tensile property test: According to GB / T 1040.1-2018 standard, type I standard dumbbell-shaped specimens were cut longitudinally from the plastic bottle body, with 5 specimens taken from each group. The test conditions were 23±2℃, relative humidity 50±5%, and tensile speed 5 mm / min. The tensile strength was recorded and the average value was taken.

[0049] Drop performance test: The test shall be conducted in accordance with BB / T 0044-2007 Packaging Containers Plastic Pesticide Bottles. Fill the plastic bottle with the nominal capacity of water, seal it, and drop it freely from a height of 1.5 m onto a concrete ground, dropping it vertically downwards from the bottle opening. Repeat this 5 times and record whether any damage or leakage occurs.

[0050] (3) UV aging resistance test Referring to ASTM G154 standard, a UVA-340 fluorescent ultraviolet lamp was used, with an irradiance of 0.89 W / (m²). 2 (nm)@340nm, light cycle: 60℃ light exposure for 8 h → 50℃ condensation for 4 h. After aging for 480 h, samples were taken to test tensile strength and the tensile strength retention rate was calculated.

[0051] (4) Degradation performance test The test was conducted in accordance with the GB / T 19277.1-2011 standard. The composting temperature was 58±2℃, the relative humidity was 50±5%, and the test period was 180 days. Microcrystalline cellulose was used as the reference material, and the biodegradation rate was calculated. The results are shown in Table 1.

[0052] Table 1 ×10 -14 As can be seen from Table 1, the environmentally friendly biodegradable plastic bottles prepared in Examples 4-6 of this invention all have low oxygen permeability, water vapor permeability coefficient and xylene permeation, high tensile strength and UV aging resistance, and no damage or leakage during drop tests. The biodegradation rate after 180 days is all above 90%, which meets the requirements for the use of biodegradable plastic bottles.

[0053] Compared to Example 4, Comparative Example 1 (without nano-clay) showed an increase in oxygen permeability, water vapor permeability, and xylene permeation. This indicates that the "maze effect" formed by nano-clay in the polymer matrix effectively prolongs the diffusion path of gas and solvent molecules, significantly improving the barrier properties of the plastic bottle.

[0054] Compared to Example 4, Comparative Example 2 (without tetrahydrocurcumin multi-effect stabilizer) showed a decrease in tensile strength, and its tensile strength retention rate after 480 hours of UV aging also decreased to 54.8%. Furthermore, in the drop test, Comparative Example 2 experienced bottom cracking on the fourth drop. Analysis reveals that the hindered amine and phosphite in the tetrahydrocurcumin multi-effect stabilizer form a phosphorus-nitrogen synergistic antioxidant system, effectively protecting the polymer matrix during high-temperature processing and UV aging. Simultaneously, the long carbon chain of stearic acid improves the compatibility between the stabilizer and the matrix, thereby improving the interfacial bonding of the blend system and significantly enhancing the mechanical properties and UV aging resistance of the plastic bottle.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. The basic principles and main features of the present invention have been described above with specific implementation schemes. Based on the present invention, some modifications or substitutions can be made, but these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of protection claimed by the present invention.

Claims

1. An environmentally friendly biodegradable plastic bottle, characterized in that, The raw materials include the following parts by weight: 60-85 parts polybutylene succinate, 10-30 parts polylactic acid, 2-5 parts compatibilizer, 1-5 parts nano clay, 1-3 parts tetrahydrocurcumin multi-effect stabilizer, and 0.1-0.5 parts lubricant. The structural formula of the tetrahydrocurcumin multi-effect stabilizer is as follows: 。 2. The environmentally friendly biodegradable plastic bottle according to claim 1, characterized in that, The preparation process of the tetrahydrocurcumin multi-effect stabilizer is as follows: (1) In the presence of formaldehyde, tetrahydrocurcumin was reacted with 4-amino-2,2,6,6-tetramethylpiperidine under reflux in ethanol to obtain intermediate 1; the structural formula of intermediate 1 is as follows: (2) In the presence of a quaternary ammonium salt phase transfer catalyst, intermediate 1 is added to epichlorohydrin to carry out a ring-opening reaction, followed by a ring-closing reaction under the action of a strong base to obtain intermediate 2; the structural formula of intermediate 2 is as follows: (3) In the presence of an organophosphorus catalyst, intermediate 2 is subjected to a ring-opening grafting reaction with stearic acid in toluene to obtain intermediate 3; the structural formula of intermediate 3 is as follows: (4) Under vacuum degree ≤ -0.09 MPa, intermediate 3 is subjected to transesterification reaction with diphenyl phosphite to obtain the tetrahydrocurcumin multi-effect stabilizer.

3. The environmentally friendly biodegradable plastic bottle according to claim 2, characterized in that, In step (1), the molar ratio of tetrahydrocurcumin, 4-amino-2,2,6,6-tetramethylpiperidine and formaldehyde is 1:(2.2-2.5):(2.2-2.5); the reflux reaction time is 5-6 h.

4. The environmentally friendly biodegradable plastic bottle according to claim 2, characterized in that, In step (2), the quaternary ammonium salt phase transfer catalyst is tetrabutylammonium bromide; the strong base is sodium hydroxide; the molar ratio of intermediate 1, epichlorohydrin, quaternary ammonium salt phase transfer catalyst and strong base is 1:(10-15):(0.05-0.06):(2.2-2.4); the ring-opening reaction temperature is 60-70℃ and the time is 2-3 h; the ring-closing reaction temperature is 70-75℃ and the time is 4-5 h.

5. The environmentally friendly biodegradable plastic bottle according to claim 2, characterized in that, The organophosphorus catalyst in step (3) is triphenylphosphine; the molar ratio of intermediate 2, stearic acid and organophosphorus catalyst is 1:(2-2.1):(0.01-0.02); the ring-opening grafting reaction is carried out at a temperature of 110-120℃ for 6-8 h.

6. The environmentally friendly biodegradable plastic bottle according to claim 2, characterized in that, In step (4), the molar ratio of intermediate 3 to diphenyl phosphite is 1:(2-2.2); the transesterification reaction is carried out at a temperature of 130-140℃ for 4-5 h.

7. The environmentally friendly biodegradable plastic bottle according to claim 1, characterized in that, The compatibilizer is maleic anhydride-grafted polybutylene succinate; the lubricant is calcium stearate.

8. A method for preparing an environmentally friendly biodegradable plastic bottle according to any one of claims 1-7, characterized in that, Includes the following steps: (a) According to the stated weight proportions, after drying polybutylene succinate and polylactic acid, they are mixed evenly with tetrahydrocurcumin multi-effect stabilizer, nano clay, compatibilizer and lubricant to obtain a mixture; (b) The mixture is melt-extruded and granulated to obtain modified particles; (c) Modified particles are injection blow molded to obtain an environmentally friendly biodegradable plastic bottle.

9. The method for preparing the environmentally friendly biodegradable plastic bottle according to claim 8, characterized in that, In step (b), the melt extrusion is performed using a twin-screw extruder with an extrusion temperature of 150-180℃ and a screw speed of 200-400 rpm.

10. The method for preparing the environmentally friendly biodegradable plastic bottle according to claim 8, characterized in that, The injection blow molding described in step (c) includes: injection molding a preform at 180-190°C, and then blow molding at 90-110°C with a blow molding pressure of 0.5-1.0 MPa.

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