Anti-aging plastic packaging material and preparation method thereof

Abstract

The present invention relates to the field of plastic packaging preparation technology, and in particular to a kind of anti-aging plastic packaging material and preparation method thereof, comprising the following components by mass: 100-140 parts of polylactic acid, 60-80 parts of PBAT, 2-5 parts of composite anti-aging agent, 1-2 parts of lubricant, 2-4 parts of flame retardant and 3-6 parts of compatibilizer, wherein the composite anti-aging agent includes a modified anti-aging agent obtained by compounding functionalized montmorillonite and modified silica, wherein the functionalized montmorillonite is carnosic acid grafted rare earth ion modified montmorillonite, and the modified silica is epoxy methyl oleate grafted silica. The anti-aging plastic packaging material provided by the present invention constructs a plastic material system with multiple protection mechanisms through the synergistic effect of each component, and the prepared plastic packaging material not only maintains good biodegradability, but also has excellent anti-ultraviolet light and antioxidant properties.

Description

Technical Field

[0001] The present invention relates to the technical field of plastic packaging preparation, and in particular to an anti-aging plastic packaging material and a preparation method thereof. Background Art

[0002] Plastic packaging materials, due to their lightweight, high strength, easy formability, and waterproof and moisture-resistant properties, are widely used in packaging for food, pharmaceuticals, cosmetics, electronics, and other fields. With growing environmental awareness, biodegradable plastic packaging materials have seen rapid development in recent years, with polylactic acid (PLA) and polybutylene terephthalate-adipate (PBAT) being among the most popular biodegradable materials. However, traditional biodegradable plastic packaging materials are prone to aging during use, manifesting as decreased mechanical properties, yellowing, and cracking, which seriously impacts their service life and application scope.

[0003] Patent CN202411896240.4 proposes biodegradable plastic particles, their preparation method, and applications. The biodegradable plastic particles comprise the following components by weight: 50-80 parts PLA, 20-50 parts PBAT, 5-20 parts filler, 1-8 parts toughening agent, 1-5 parts lubricant, and 5-10 parts modifier. The modifier comprises a polylactic acid-polyethylene glycol block copolymer and a polycaprolactone-polyglycidyl methacrylate block copolymer in a mass ratio of 1:19-19:1. This technical solution addresses the poor flexibility and strength of plastic particles in related technologies. However, this technology has obvious defects: on the one hand, it does not take into account the impact of environmental factors such as ultraviolet radiation and oxidation that the material faces during actual use, and lacks effective anti-aging functional components; on the other hand, its modification system mainly focuses on improving mechanical properties and cannot effectively block ultraviolet radiation and free radical diffusion. As a result, the material is prone to photooxidative degradation when used outdoors or in strong light environments, and its service life is significantly shortened, which seriously limits the application scope and scenarios of this type of plastic packaging material. Summary of the Invention

[0004] In view of this, the present invention proposes an anti-aging plastic packaging material and a preparation method thereof to solve the technical problems in the prior art of biodegradable plastic packaging materials, such as poor resistance to ultraviolet radiation and oxidation, short service life and limited applicable environment.

[0005] The technical solution of the present invention is achieved as follows: The present invention provides an anti-aging plastic packaging material, which includes the following components, by mass: 100-140 parts of polylactic acid, 60-80 parts of PBAT, 2-5 parts of a composite anti-aging agent, 1-2 parts of a lubricant, 2-4 parts of a flame retardant and 3-6 parts of a compatibilizer, wherein the composite anti-aging agent includes a modified anti-aging agent obtained by compounding functionalized montmorillonite and modified silica, wherein the functionalized montmorillonite is a carnosic acid-grafted rare earth ion-modified montmorillonite, and the modified silica is epoxy methyl oleate-grafted silica.

[0006] The present invention compounds polylactic acid with PBAT and introduces a composite anti-aging agent system, in which functionalized montmorillonite and modified silica work synergistically to form a multi-level protection mechanism that not only effectively blocks ultraviolet radiation, but also captures and neutralizes free radicals, inhibiting the diffusion of oxidative degradation chain reactions. At the same time, the addition of a compatibilizer improves the interfacial bonding between the components, the lubricant improves processing fluidity, and the flame retardant enhances the flame retardant properties of the material, so that the resulting plastic packaging material has excellent resistance to ultraviolet light, oxidation, and heat aging, while having little effect on its degradability, significantly extending the material's service life and environmental adaptability, and providing a new technical approach for the promotion and application of biodegradable plastic packaging materials.

[0007] On the basis of the above technical solution, preferably, the preparation method of the modified anti-aging agent includes:

[0008] S1. Rare earth ion-modified montmorillonite is dispersed in an ethanol / water solution, a bisaminosilane coupling agent is added, and the mixture is stirred at room temperature for 1-2 hours, and then heated to 60-70°C and stirred for 3-4 hours to obtain silane-modified montmorillonite;

[0009] S2. Dispersing the silane-modified montmorillonite in an ethanol / water solution, adding carnosic acid, and then adding 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide, stirring at room temperature for 0.5-1 h, heating to 40-50° C. and stirring for 7-8 h to obtain functionalized montmorillonite;

[0010] S3, dispersing nano-silica in an ethanol / water solution, adding an aminosilane coupling agent, heating to 70-80°C and reacting for 4-6 hours to obtain amino-silica;

[0011] S4, dispersing the amino-silica in anhydrous ethanol, adding methyl epoxyoleate and p-toluenesulfonic acid, heating to 60-70° C. and stirring for 4-6 hours to obtain modified silica;

[0012] S5. Dispersing the modified silica and functionalized montmorillonite in ethanol, adding glutaraldehyde aqueous solution, adjusting the pH to 5.5-6.0, stirring and reacting at 40-50° C. for 8-10 hours to obtain a modified anti-aging agent.

[0013] Specifically, in step S1, the abundant hydroxyl groups on the surface of rare earth ion-modified montmorillonite react with the methoxy group of the bisaminosilane coupling agent to successfully introduce amino groups onto the montmorillonite surface. Silane modification solves the incompatibility issue between inorganic montmorillonite and organic matrices. The silanized montmorillonite surface is transformed from hydrophilic to organophilic, and the amino groups introduced onto the surface provide active reaction sites for subsequent functionalization. Simultaneously, the formation of the silane layer protects the rare earth ions, preventing their loss during subsequent processing and use, thereby ensuring the durability of the anti-aging properties. In step S2, the amino groups on the silane-modified montmorillonite undergo an amidation reaction with the carboxyl groups of carnosic acid, grafting carnosic acid, which has a polyphenolic structure, onto the montmorillonite surface. The phenolic hydroxyl groups and conjugated double bond structure in the carnosic acid molecule can improve antioxidant efficiency. At the same time, its aromatic structure also has ultraviolet absorption capacity, which can reduce ultraviolet damage to the material. In step S3, the surface activity of the aminated silica is enhanced, and its organophilicity is improved, effectively preventing the agglomeration of silica nanoparticles in the polymer matrix and improving interfacial compatibility. At the same time, the amino groups introduced on the surface provide reaction sites for the subsequent grafting of epoxy methyl oleate, laying the foundation for the construction of a multifunctional anti-aging system. In step S4, the amino groups on the surface of the aminated silica react with the epoxy groups in the epoxy methyl oleate molecules to graft the epoxy methyl oleate to the silica surface and generate hydroxyl groups for subsequent cross-linking reactions. The ester groups in the epoxy methyl oleate molecules can effectively absorb and scatter ultraviolet radiation, reducing the direct attack of ultraviolet rays on the polymer backbone and preventing the breakage of CC bonds during photodegradation. In addition, the long chains of the epoxy methyl oleate molecules can improve the toughness of the material while being environmentally friendly.

[0014] In step S5, the amino groups remaining on the functionalized montmorillonite and the hydroxyl groups on the modified silica are covalently linked using glutaraldehyde as a cross-linking agent, thereby achieving a multi-component synergistic anti-aging effect: the layered montmorillonite and silica form a complementary physical barrier, significantly improving the oxygen barrier performance; the free radical capture ability of carnosic acid and the peroxide decomposition ability of rare earth ions work synergistically to comprehensively improve the antioxidant efficiency; the ultraviolet absorption ability of epoxy methyl oleate and the ultraviolet scattering ability of montmorillonite synergistically enhance the anti-ultraviolet light aging performance; in addition, the composite structure fixes each functional component on the nanocarrier, preventing them from migrating and volatilizing during the processing process, thereby ensuring the durability and stability of the anti-aging effect.

[0015] Based on the above technical solution, preferably, in step S1, the preparation method of rare earth ion-modified montmorillonite is as follows:

[0016] Sodium montmorillonite, lanthanum nitrate and cerium nitrate are mixed in deionized water, ultrasonically dispersed, heated to 90-100°C and stirred for reaction for 20-24 hours, centrifuged and dried to obtain rare earth ion-modified montmorillonite, wherein the ratio of sodium montmorillonite, lanthanum nitrate and cerium nitrate is 1:(0.8-1.5):(0.8-1.5).

[0017] By La in lanthanum nitrate and cerium nitrate in aqueous phase 3+ and Ce 3+ Na between the Na-montmorillonite layers + Ion exchange reaction occurs. Since rare earth ions have higher charge density and stronger electrostatic force, they can be firmly combined with the interlayer position of montmorillonite, thus achieving stable loading of rare earth ions. This modification gives montmorillonite multiple anti-aging functions: on the one hand, La 3+ and Ce 3+ It has the characteristic of variable valence state and can catalytically decompose peroxides produced during the aging process of polymers; on the other hand, rare earth ions can efficiently absorb and convert ultraviolet light energy, reducing the direct damage of ultraviolet radiation to polymers; in addition, the introduction of rare earth ions increases the interlayer spacing of montmorillonite, improves its compatibility and dispersibility with organic molecules, and strengthens the physical barrier effect of montmorillonite; finally, rare earth ions form a synergistic effect with the subsequently grafted carnosic acid, the former decomposing peroxides and the latter capturing free radicals, constructing a comprehensive antioxidant defense system.

[0018] Based on the above technical solution, preferably, in step S1, the mass ratio of the rare earth ion-modified montmorillonite to the bisaminosilane coupling agent is 100:3-7, and the bisaminosilane coupling agent is an aminoethylaminopropylmethoxysilane coupling agent.

[0019] Based on the above technical solution, preferably, in step S2, the mass ratio of silane-modified montmorillonite, carnosic acid, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide is 100:5-10:3-6:2-4.

[0020] On the basis of the above technical solution, preferably, in step S3, the mass ratio of nano-silica to aminosilane coupling agent is 100:5-8, and the aminosilane coupling agent is 3-aminopropyltriethoxysilane.

[0021] Based on the above technical solution, preferably, in step S4, the mass ratio of amino silica, epoxy methyl oleate and p-toluenesulfonic acid is 100:10-15:0.3-0.7.

[0022] On the basis of the above technical solution, preferably, the composite anti-aging agent also includes a benzotriazole ultraviolet absorber, the mass ratio of the benzotriazole ultraviolet absorber to the modified anti-aging agent is 1:3-4, and the benzotriazole ultraviolet absorber is 2-(2-hydroxy-5-methylphenyl)benzotriazole or 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole.

[0023] There is an intramolecular hydrogen bond between the hydroxyl group and the triazole ring in the molecular structure of benzotriazole compounds, which can strongly and selectively absorb ultraviolet rays in the 290-400nm band. After absorbing energy, the energy is harmlessly converted and dissipated through the rapid tautomerism of the hydroxyl proton, forming an "excitation-conversion-dissipation" photostable cycle, which complements the modified anti-aging agent. Specifically, in terms of ultraviolet protection, a triple mechanism of "absorption-scattering-conversion" is formed. Benzotriazole molecules absorb ultraviolet rays, nanoparticles scatter ultraviolet rays, and rare earth ions convert ultraviolet energy, achieving full-band and high-efficiency Secondly, benzotriazole molecules are small and easy to migrate and volatilize. After being compounded with modified anti-aging agents, they can be fixed on the surface or around the nanocarrier through intermolecular forces, significantly reducing their migration and loss during processing and use, and prolonging the anti-aging effect; thirdly, there is a synergistic effect between the components in the composite system. The absorption of ultraviolet rays by benzotriazole reduces the antioxidant burden of carnosic acid, and the decomposition of peroxides by rare earth ions provides a more stable working environment for benzotriazole, together building a comprehensive protective barrier against multiple aging factors such as light, oxygen and heat.

[0024] On the basis of the above technical solution, preferably, the lubricant is calcium stearate or polyethylene wax, the flame retardant is triphenyl phosphate or tricresyl phosphate, and the compatibilizer is maleic anhydride grafted polylactic acid.

[0025] The present invention also provides a method for preparing an anti-aging plastic packaging material, comprising the following steps:

[0026] S1. Place 85-90% of polylactic acid, PBAT, compatibilizer, lubricant and flame retardant in a drying oven, dry at 70-80° C. for 6-8 hours, and premix for 5-10 minutes to obtain a first mixture;

[0027] S2. Premixing the composite anti-aging agent with 10-15% of polylactic acid for 3-5 minutes to obtain a second mixture;

[0028] S3, premixing the first mixed material and the second mixed material for 2-3 minutes, adding the mixture to a twin-screw extruder, setting the temperature to 160-190° C. and the screw speed to 80-120 r / min, and melt blending to obtain a molten material;

[0029] S4. Extruding, granulating and blow-molding the molten material to obtain an anti-aging plastic packaging material.

[0030] The anti-aging plastic packaging material and preparation method thereof of the present invention have the following beneficial effects compared with the prior art:

[0031] (1) The anti-aging plastic packaging material provided by the present invention constructs a bioplastic material system with multiple protection mechanisms through the rational compounding of polylactic acid and PBAT, the introduction of a composite anti-aging agent, and the synergistic effect of lubricants, flame retardants and compatibilizers, thereby solving the technical problem that existing biodegradable plastics are prone to aging under ultraviolet light irradiation and oxidative environments. The prepared plastic packaging material not only maintains good biodegradability, but also has excellent anti-ultraviolet light and antioxidant properties.

[0032] (2) The modified anti-aging agent obtained by compounding functionalized montmorillonite and modified silica in the present invention forms a complementary physical barrier. The phenolic hydroxyl group of carnosic acid efficiently captures free radicals, rare earth ions catalyze the decomposition of peroxides, nanoparticles shield ultraviolet rays and oxygen penetration, and the unsaturated bonds and ester groups in the epoxy oleate molecule can effectively absorb ultraviolet energy and convert it into heat energy. The synergistic effect of the three blocks the propagation of the photooxidative aging chain reaction. At the same time, the fixing effect of the nanocarrier prevents the migration and loss of the anti-aging functional groups, ensuring the durability of the anti-aging effect.

[0033] (3) The combination of benzotriazole UV absorbers and modified anti-aging agents constructs a "selective absorption-scattering-conversion" multiple protection system. Benzotriazole compounds selectively absorb ultraviolet rays and convert them harmlessly through the intramolecular hydrogen bond transfer mechanism, which complements the scattering effect of nanoparticles and the energy conversion effect of rare earth ions, significantly enhancing the material's resistance to ultraviolet aging. Benzotriazole's absorption of ultraviolet rays reduces the antioxidant burden of carnosic acid, while the decomposition of peroxides by rare earth ions provides benzotriazole with a more stable working environment, jointly constructing a comprehensive protection barrier against multiple aging factors such as light, oxygen and heat. DETAILED DESCRIPTION

[0034] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] Aminoethylaminopropylmethoxysilane coupling agent was purchased from Yisheng New Materials Co., Ltd., model OFS-6020; polylactic acid was purchased from Shanghai Yuanye Biotechnology Co., Ltd., with a molecular weight of 3000-15000; PBAT was purchased from Dongguan Shunying Plastic Raw Materials Co., Ltd., model F2224; triphenyl phosphate was purchased from Hubei Kewode Chemical Co., Ltd.; maleic anhydride grafted polylactic acid was purchased from Xi'an Qiyue Biotechnology Co., Ltd.

[0036] Example 1

[0037] This embodiment provides an anti-aging plastic packaging material, comprising the following components: 120 parts of polylactic acid, 70 parts of PBAT, 3.5 parts of a composite anti-aging agent, 1.5 parts of calcium stearate, 3 parts of triphenyl phosphate, and 4.5 parts of maleic anhydride-grafted polylactic acid. The composite anti-aging agent is composed of 2-(2-hydroxy-5-methylphenyl)benzotriazole and a modified anti-aging agent in a mass ratio of 1:3.5. The modified anti-aging agent is prepared as follows:

[0038] (1) 100 g of sodium montmorillonite was dispersed in 2 L of deionized water and ultrasonically dispersed for 12 min. Then, 115 g of lanthanum nitrate and 115 g of cerium nitrate were added and ultrasonically dispersed for another 12 min. The mixture was heated to 95 °C and stirred for 22 h. After cooling to room temperature, the mixture was centrifuged and washed three times with deionized water to remove unexchanged nitrates. The mixture was vacuum dried and ground through a 200 mesh sieve to obtain rare earth ion-modified montmorillonite.

[0039] (2) 100 g of rare earth ion-modified montmorillonite was dispersed in 1 L of ethanol / water solution (volume ratio of 7:3), 5 g of aminoethylaminopropylmethoxysilane coupling agent (pre-dissolved in 50 ml of ethanol) was added, and stirred at room temperature for 1.5 h. The mixture was heated to 65 °C and stirred for 3-4 h. The mixture was cooled to room temperature, centrifuged, washed twice with ethanol and deionized water, and dried in vacuo to obtain silane-modified montmorillonite.

[0040] (3) Disperse 100 g of silane-modified montmorillonite in 800 ml of ethanol / water solution (volume ratio of 4:1), ultrasonically disperse, add 8 g of carnosic acid, stir for 15 min, then add 4.5 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and 3 g of N-hydroxysuccinimide, stir at room temperature for 0.8 h, adjust the pH to 6.5-7.0, heat to 45 °C and stir for 7.5 h, cool to room temperature, centrifuge, wash twice with DMF, ethanol and deionized water, and vacuum dry to obtain functionalized montmorillonite;

[0041] (4) Disperse 100 g of nano-silica in 1 L of ethanol / water solution (volume ratio 4:1), ultrasonically disperse, add 6.5 g of 3-aminopropyltriethoxysilane, heat to 75 °C and react for 5 h, cool to room temperature, centrifuge, wash with ethanol and deionized water three times each, and vacuum dry to obtain amino-silica;

[0042] (5) Disperse 100 g of amino-modified silica in 800 ml of anhydrous ethanol, ultrasonically disperse, add 13 g of methyl epoxyoleate, stir for 15 min, then add 0.5 g of p-toluenesulfonic acid, heat to 65 °C and stir for 5 h, cool to room temperature, centrifuge, wash with anhydrous ethanol 4 times to remove unreacted reagents, and vacuum dry to obtain modified silica;

[0043] (6) Disperse 60 g of modified silica and 40 g of functionalized montmorillonite in 1 L of ethanol, perform ultrasonic dispersion, add 50 ml of 25% glutaraldehyde aqueous solution, stir for 15 min, adjust the pH to 5.8 with dilute hydrochloric acid (0.1 mol / L), heat to 45 °C and stir for 9 h, cool to room temperature, centrifuge, wash with ethanol and deionized water three times each, vacuum dry, and grind through a 200 mesh sieve to obtain a modified anti-aging agent.

[0044] The preparation method of the anti-aging plastic packaging material is as follows:

[0045] 105 parts of polylactic acid, 70 parts of PBAT, 4 parts of maleic anhydride grafted polyethylene, 1.5 parts of calcium stearate and 3 parts of ammonium polyphosphate are placed in a drying oven, dried at 75°C for 7 hours, and premixed for 8 minutes to obtain a first mixture; 3 parts of a composite anti-aging agent are premixed with 15 parts of polylactic acid for 4 minutes to obtain a second mixture; the first mixture and the second mixture are premixed for 2.5 minutes, added to a twin-screw extruder, set the temperature to 160-190°C, the screw speed to 100 r / min, and melt blended to obtain a molten material; the molten material is extruded, granulated and blow-molded to obtain an anti-aging plastic packaging material.

[0046] Example 2

[0047] This embodiment provides an anti-aging plastic packaging material, comprising the following components: 100 parts of polylactic acid, 60 parts of PBAT, 2 parts of a composite anti-aging agent, 1 part of polyethylene wax, 2 parts of tricresyl phosphate, and 3 parts of maleic anhydride-grafted polylactic acid. The composite anti-aging agent is composed of 2-(2-hydroxy-5-methylphenyl)benzotriazole and a modified anti-aging agent in a mass ratio of 1:3. The modified anti-aging agent is prepared as follows:

[0048] (1) 100 g of sodium montmorillonite was dispersed in 2 L of deionized water and ultrasonically dispersed for 10 min. Then, 80 g of lanthanum nitrate and 80 g of cerium nitrate were added and ultrasonically dispersed for another 10 min. The mixture was heated to 90 °C and stirred for 24 h. After cooling to room temperature, the mixture was centrifuged and washed three times with deionized water to remove unexchanged nitrates. The mixture was vacuum dried and ground through a 200 mesh sieve to obtain rare earth ion-modified montmorillonite.

[0049] (2) 100 g of rare earth ion-modified montmorillonite was dispersed in 1 L of ethanol / water solution (volume ratio of 7:3), 3 g of aminoethylaminopropylmethoxysilane coupling agent (pre-dissolved in 30 ml of ethanol) was added, and the mixture was stirred at room temperature for 1 h, heated to 60 °C for 4 h, cooled to room temperature, centrifuged, washed twice with ethanol and deionized water, and dried in vacuo to obtain silane-modified montmorillonite;

[0050] (3) Disperse 100 g of silane-modified montmorillonite in 800 ml of ethanol / water solution (volume ratio of 4:1), ultrasonically disperse, add 5 g of carnosic acid, stir for 15 min, then add 3 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and 2 g of N-hydroxysuccinimide, stir at room temperature for 0.5 h, adjust the pH to 6.5-7.0, heat to 40 °C and stir for 8 h, cool to room temperature, centrifuge, wash twice with DMF, ethanol and deionized water, and vacuum dry to obtain functionalized montmorillonite;

[0051] (4) Disperse 100 g of nano-silica in 1 L of ethanol / water solution (volume ratio 4:1), ultrasonically disperse, add 5 g of 3-aminopropyltriethoxysilane, heat to 70 °C and react for 6 h, cool to room temperature, centrifuge, wash with ethanol and deionized water three times each, and vacuum dry to obtain amino-silica;

[0052] (5) Disperse 100 g of amino-modified silica in 800 ml of anhydrous ethanol, ultrasonically disperse, add 10 g of methyl epoxyoleate, stir for 15 min, then add 0.3 g of p-toluenesulfonic acid, heat to 60 °C and stir for 6 h, cool to room temperature, centrifuge, wash with anhydrous ethanol 4 times to remove unreacted reagents, and vacuum dry to obtain modified silica;

[0053] (6) Disperse 55 g of modified silica and 35 g of functionalized montmorillonite in 1 L of ethanol, ultrasonically disperse, add 45 ml of 25% glutaraldehyde aqueous solution, stir for 15 min, adjust the pH to 5.8 with dilute hydrochloric acid (0.1 mol / L), heat to 40 °C and stir for 10 h, cool to room temperature, centrifuge, wash with ethanol and deionized water three times each, vacuum dry, and grind through a 200 mesh sieve to obtain a modified anti-aging agent.

[0054] The preparation method of the anti-aging plastic packaging material is as follows:

[0055] 90 parts of polylactic acid, 60 parts of PBAT, 3 parts of maleic anhydride grafted polylactic acid, 1 part of polyethylene wax and 2 parts of tricresyl phosphate are placed in a drying oven, dried at 70°C for 8 hours, and premixed for 5 minutes to obtain a first mixture; 2 parts of a composite anti-aging agent are premixed with 10 parts of polylactic acid for 3 minutes to obtain a second mixture; the first mixture and the second mixture are premixed for 2 minutes, added to a twin-screw extruder, set the temperature to 160-190°C, the screw speed to 80r / min, and melt blended to obtain a molten material; the molten material is extruded, granulated and blow-molded to obtain an anti-aging plastic packaging material.

[0056] Example 3

[0057] This embodiment provides an anti-aging plastic packaging material, comprising the following components: 140 parts of polylactic acid, 80 parts of PBAT, 5 parts of a composite anti-aging agent, 2 parts of calcium stearate, 4 parts of triphenyl phosphate, and 6 parts of maleic anhydride-grafted polylactic acid. The composite anti-aging agent is composed of 2-(2-hydroxy-5-methylphenyl)benzotriazole and a modified anti-aging agent in a mass ratio of 1:4. The modified anti-aging agent is prepared as follows:

[0058] (1) Disperse 100 g of sodium montmorillonite in 2 L of deionized water and ultrasonically disperse for 15 min. Then add 150 g of lanthanum nitrate and 150 g of cerium nitrate and continue ultrasonically dispersing for 15 min. Heat to 100 °C and stir for 20 h. After cooling to room temperature, centrifuge and wash with deionized water three times to remove unexchanged nitrate. Dry in vacuum and grind through a 200 mesh sieve to obtain rare earth ion-modified montmorillonite.

[0059] (2) 100 g of rare earth ion-modified montmorillonite was dispersed in 1 L of ethanol / water solution (volume ratio of 7:3), 7 g of aminoethylaminopropylmethoxysilane coupling agent (pre-dissolved in 70 ml of ethanol) was added, and stirred at room temperature for 2 h. The mixture was heated to 70 °C and stirred for 3 h. The mixture was cooled to room temperature, centrifuged, washed twice with ethanol and deionized water, and dried in vacuo to obtain silane-modified montmorillonite.

[0060] (3) Disperse 100 g of silane-modified montmorillonite in 800 ml of ethanol / water solution (volume ratio of 4:1), ultrasonically disperse, add 10 g of carnosic acid, stir for 15 min, then add 6 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and 4 g of N-hydroxysuccinimide, stir at room temperature for 1 h, adjust the pH to 6.5-7.0, heat to 50 °C and stir for 7 h, cool to room temperature, centrifuge, wash twice with DMF, ethanol and deionized water respectively, and vacuum dry to obtain functionalized montmorillonite;

[0061] (4) Disperse 100 g of nano-silica in 1 L of ethanol / water solution (volume ratio 4:1), ultrasonically disperse, add 8 g of 3-aminopropyltriethoxysilane, heat to 80 °C and react for 4 h, cool to room temperature, centrifuge, wash with ethanol and deionized water three times each, and vacuum dry to obtain amino-silica;

[0062] (5) Disperse 100 g of amino-modified silica in 800 ml of anhydrous ethanol, ultrasonically disperse, add 15 g of methyl epoxyoleate, stir for 15 min, then add 0.7 g of p-toluenesulfonic acid, heat to 70 °C and stir for 4 h, cool to room temperature, centrifuge, wash with anhydrous ethanol 4 times to remove unreacted reagents, and vacuum dry to obtain modified silica;

[0063] (6) Disperse 65 g of modified silica and 45 g of functionalized montmorillonite in 1 L of ethanol, perform ultrasonic dispersion, add 50 ml of 25% glutaraldehyde aqueous solution, stir for 15 min, adjust the pH to 5.8 with dilute hydrochloric acid (0.1 mol / L), heat to 50 °C and stir for 8 h, cool to room temperature, centrifuge, wash with ethanol and deionized water three times each, vacuum dry, and grind through a 200 mesh sieve to obtain a modified anti-aging agent.

[0064] The preparation method of the anti-aging plastic packaging material is as follows:

[0065] 119 parts of polylactic acid, 80 parts of PBAT, 6 parts of maleic anhydride grafted polylactic acid, 2 parts of calcium stearate and 4 parts of triphenyl phosphate are placed in a drying oven, dried at 80°C for 6 hours, and premixed for 10 minutes to obtain a first mixture; 5 parts of a composite anti-aging agent are premixed with 21 parts of polylactic acid for 5 minutes to obtain a second mixture; the first mixture and the second mixture are premixed for 3 minutes, added to a twin-screw extruder, set the temperature to 160-190°C, the screw speed to 120r / min, and melt blended to obtain a molten material; the molten material is extruded, granulated and blow-molded to obtain an anti-aging plastic packaging material.

[0066] Comparative Example 1

[0067] This comparative example provides an anti-aging plastic packaging material, comprising the following components: 120 parts of polylactic acid, 70 parts of PBAT, 3.5 parts of a composite anti-aging agent, 1.5 parts of calcium stearate, 3 parts of triphenyl phosphate, and 4.5 parts of maleic anhydride-grafted polylactic acid. The composite anti-aging agent is a modified anti-aging agent, wherein the preparation method of the modified anti-aging agent is the same as that of Example 1.

[0068] Comparative Example 2

[0069] This comparative example provides an anti-aging plastic packaging material, comprising the following components: 120 parts of polylactic acid, 70 parts of PBAT, 3.5 parts of a composite anti-aging agent, 1.5 parts of calcium stearate, 3 parts of triphenyl phosphate, and 4.5 parts of maleic anhydride-grafted polylactic acid, wherein the composite anti-aging agent is composed of 2-(2-hydroxy-5-methylphenyl)benzotriazole and a modified anti-aging agent in a mass ratio of 1:3.5. The difference between the preparation method of the modified anti-aging agent and that of Example 1 is that the montmorillonite is not modified with rare earth ions, that is:

[0070] (1) 100 g of sodium montmorillonite was dispersed in 1 L of ethanol / water solution (volume ratio 7:3), and 5 g of aminoethylaminopropylmethoxysilane coupling agent (pre-dissolved in 50 ml of ethanol) was added. The mixture was stirred at room temperature for 1.5 h, heated to 65 °C and stirred for 3-4 h, cooled to room temperature, centrifuged, washed twice with ethanol and deionized water, and dried in vacuo to obtain silane-modified montmorillonite. The subsequent steps were the same as in Example 1.

[0071] Comparative Example 3

[0072] This comparative example provides an anti-aging plastic packaging material, comprising the following components: 120 parts of polylactic acid, 70 parts of PBAT, 3.5 parts of a composite anti-aging agent, 1.5 parts of calcium stearate, 3 parts of triphenyl phosphate, and 4.5 parts of maleic anhydride-grafted polylactic acid, wherein the composite anti-aging agent is composed of 2-(2-hydroxy-5-methylphenyl)benzotriazole and a modified anti-aging agent in a mass ratio of 1:3.5. The difference between the preparation method of the modified anti-aging agent and that of Example 1 is that the montmorillonite is not grafted with carnosic acid, that is:

[0073] (1) 100 g of sodium montmorillonite was dispersed in 2 L of deionized water and ultrasonically dispersed for 12 min. Then, 115 g of lanthanum nitrate and 115 g of cerium nitrate were added and ultrasonically dispersed for another 12 min. The mixture was heated to 95 °C and stirred for 22 h. After cooling to room temperature, the mixture was centrifuged and washed three times with deionized water to remove unexchanged nitrates. The mixture was vacuum dried and ground through a 200 mesh sieve to obtain rare earth ion-modified montmorillonite.

[0074] (2) 100 g of rare earth ion-modified montmorillonite was dispersed in 1 L of ethanol / water solution (volume ratio of 7:3), 5 g of aminoethylaminopropylmethoxysilane coupling agent (pre-dissolved in 50 ml of ethanol) was added, and stirred at room temperature for 1.5 h. The mixture was heated to 65 °C and stirred for 3-4 h. The mixture was cooled to room temperature, centrifuged, washed twice with ethanol and deionized water, and dried in vacuo to obtain silane-modified montmorillonite.

[0075] (3) Disperse 100 g of nano-silica in 1 L of ethanol / water solution (volume ratio 4:1), ultrasonically disperse, add 6.5 g of 3-aminopropyltriethoxysilane, heat to 75 °C and react for 5 h, cool to room temperature, centrifuge, wash with ethanol and deionized water three times each, and vacuum dry to obtain amino-silica;

[0076] (4) Disperse 100 g of amino-modified silica in 800 ml of anhydrous ethanol, ultrasonically disperse, add 13 g of methyl epoxyoleate, stir for 15 min, then add 0.5 g of p-toluenesulfonic acid, heat to 65 °C and stir for 5 h, cool to room temperature, centrifuge, wash with anhydrous ethanol 4 times to remove unreacted reagents, and vacuum dry to obtain modified silica;

[0077] (5) Disperse 60 g of modified silica and 40 g of silane-modified montmorillonite in 1 L of ethanol, perform ultrasonic dispersion, add 50 ml of 25% glutaraldehyde aqueous solution, stir for 15 min, adjust the pH to 5.8 with dilute hydrochloric acid (0.1 mol / L), heat to 45 °C and stir for 9 h, cool to room temperature, centrifuge, wash with ethanol and deionized water three times each, vacuum dry, and grind through a 200 mesh sieve to obtain a modified anti-aging agent.

[0078] Comparative Example 4

[0079] This comparative example provides an anti-aging plastic packaging material, comprising the following components: 120 parts of polylactic acid, 70 parts of PBAT, 3.5 parts of a composite anti-aging agent, 1.5 parts of calcium stearate, 3 parts of triphenyl phosphate, and 4.5 parts of maleic anhydride-grafted polylactic acid, wherein the composite anti-aging agent is composed of 2-(2-hydroxy-5-methylphenyl)benzotriazole and a modified anti-aging agent in a mass ratio of 1:3.5. The difference between the preparation method of the modified anti-aging agent and that of Example 1 is that the silicon dioxide is not grafted with epoxy methyl oleate, that is:

[0080] Steps (1) to (4) are the same as in Example 1;

[0081] (5) Disperse 60 g of amino-modified silica and 40 g of functionalized montmorillonite in 1 L of ethanol, perform ultrasonic dispersion, add 50 ml of 25% glutaraldehyde aqueous solution, stir for 15 min, adjust the pH to 5.8 with dilute hydrochloric acid (0.1 mol / L), heat to 45 °C and stir for 9 h, cool to room temperature, centrifuge, wash with ethanol and deionized water three times each, vacuum dry, and grind through a 200 mesh sieve to obtain a modified anti-aging agent.

[0082] Comparative Example 5

[0083] This comparative example provides an anti-aging plastic packaging material, comprising the following components: 120 parts of polylactic acid, 70 parts of PBAT, 3.5 parts of a composite anti-aging agent, 1.5 parts of calcium stearate, 3 parts of triphenyl phosphate, and 4.5 parts of maleic anhydride-grafted polylactic acid, wherein the composite anti-aging agent is composed of 2-(2-hydroxy-5-methylphenyl)benzotriazole and a modified anti-aging agent in a mass ratio of 1:3.5. The preparation method of the modified anti-aging agent is the same as that of Example 1 in that the modified silica and the functionalized montmorillonite are not cross-linked, that is:

[0084] Steps (1) to (5) are the same as in Example 1;

[0085] (6) Disperse 60 g of modified silica and 40 g of functionalized montmorillonite in 1 L of ethanol, perform ultrasonic dispersion, add 50 ml of aqueous solution, stir for 15 min, heat to 45 °C and stir for 9 h, cool to room temperature, centrifuge, wash with ethanol and deionized water three times each, vacuum dry, and grind through a 200 mesh sieve to obtain a modified anti-aging agent.

[0086] Performance testing

[0087] Standard specimens of the aging-resistant plastic packaging materials prepared in the Examples and Comparative Examples were prepared and subjected to performance testing, including tensile strength, elongation at break, heat distortion temperature, and aging performance. Tensile strength and elongation at break were tested according to GB / T 1040.3-2006, Plastics — Determination of Tensile Properties — Part 3: Film and Sheeting — Test Conditions. After hot pressing into sheets, heat distortion temperature was tested according to the relevant requirements of GB / T 1634. Aging testing involved placing the specimens in a xenon arc aging chamber at 80°C for 1200 hours. The change in tensile strength was calculated as (tensile strength after UV aging treatment / original tensile strength of the specimen) × 100%. The test results are shown in Table 1.

[0088] Table 1

[0089]

[0090] As shown in Table 1, the synergistic effect of benzotriazole and a modified antioxidant (comprising rare earth-modified montmorillonite, carnosic acid grafting, epoxy methyl oleate-modified silica, and a cross-linked structure) in the technical solution of the present invention significantly improves the mechanical properties and anti-aging performance of the material. Benzotriazole delays photoaging by absorbing ultraviolet light, the rare earth-modified montmorillonite enhances filler dispersibility and thermal stability, carnosic acid scavenges free radicals and inhibits oxidative degradation, epoxy methyl oleate improves interfacial compatibility, and the cross-linked network strengthens the bond between the filler and the matrix.

[0091] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An anti-aging plastic packaging material, characterized in that: The invention comprises the following components in parts by mass: 100-140 parts of polylactic acid, 60-80 parts of PBAT, 2-5 parts of a composite anti-aging agent, 1-2 parts of a lubricant, 2-4 parts of a flame retardant and 3-6 parts of a compatibilizer. The composite anti-aging agent comprises a modified anti-aging agent obtained by compounding functionalized montmorillonite and modified silica. The functionalized montmorillonite is a montmorillonite modified by grafting rare earth ions with carnosic acid, and the modified silica is a silica grafted with methyl epoxy oleate.

2. The anti-aging plastic packaging material according to claim 1, characterized in that: The preparation method of the modified anti-aging agent comprises: S1. Rare earth ion-modified montmorillonite is dispersed in an ethanol / water solution, a bisaminosilane coupling agent is added, and the mixture is stirred at room temperature for 1-2 hours, and then heated to 60-70°C and stirred for 3-4 hours to obtain silane-modified montmorillonite; S2. Dispersing the silane-modified montmorillonite in an ethanol / water solution, adding carnosic acid, and then adding 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide, stirring at room temperature for 0.5-1 h, heating to 40-50° C. and stirring for 7-8 h to obtain functionalized montmorillonite; S3, dispersing nano-silica in an ethanol / water solution, adding an aminosilane coupling agent, heating to 70-80°C and reacting for 4-6 hours to obtain amino-silica; S4, dispersing the amino-silica in anhydrous ethanol, adding methyl epoxyoleate and p-toluenesulfonic acid, heating to 60-70° C. and stirring for 4-6 hours to obtain modified silica; S5. Dispersing the modified silica and functionalized montmorillonite in ethanol, adding glutaraldehyde aqueous solution, adjusting the pH to 5.5-6.0, stirring and reacting at 40-50° C. for 8-10 hours to obtain a modified anti-aging agent.

3. The anti-aging plastic packaging material according to claim 2, characterized in that: In step S1, the preparation method of rare earth ion modified montmorillonite is as follows: Sodium montmorillonite, lanthanum nitrate and cerium nitrate are mixed in deionized water, ultrasonically dispersed, heated to 90-100°C and stirred for reaction for 20-24 hours, centrifuged and dried to obtain rare earth ion-modified montmorillonite, wherein the ratio of sodium montmorillonite, lanthanum nitrate and cerium nitrate is 1:(0.8-1.5):(0.8-1.5).

4. The anti-aging plastic packaging material according to claim 2, characterized in that: In step S1, the mass ratio of the rare earth ion-modified montmorillonite to the bisaminosilane coupling agent is 100:3-7, and the bisaminosilane coupling agent is an aminoethylaminopropylmethoxysilane coupling agent.

5. The anti-aging plastic packaging material according to claim 2, characterized in that: In step S2, the mass ratio of silane-modified montmorillonite, carnosic acid, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-hydroxysuccinimide is 100:5-10:3-6:2-4.

6. The anti-aging plastic packaging material according to claim 2, characterized in that: In step S3, the mass ratio of nano-silica to aminosilane coupling agent is 100:5-8, and the aminosilane coupling agent is 3-aminopropyltriethoxysilane.

7. The anti-aging plastic packaging material according to claim 2, characterized in that: In step S4, the mass ratio of amino silica, epoxy methyl oleate and p-toluenesulfonic acid is 100:10-15:0.3-0.

7.

8. The anti-aging plastic packaging material according to claim 1, characterized in that: The composite anti-aging agent also includes a benzotriazole ultraviolet absorber, the mass ratio of the benzotriazole ultraviolet absorber to the modified anti-aging agent is 1:3-4, and the benzotriazole ultraviolet absorber is 2-(2-hydroxy-5-methylphenyl)benzotriazole or 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole.

9. The anti-aging plastic packaging material according to claim 1, characterized in that: The lubricant is calcium stearate or polyethylene wax, the flame retardant is triphenyl phosphate or tricresyl phosphate, and the compatibilizer is maleic anhydride grafted polylactic acid.

10. A method for preparing an anti-aging plastic packaging material according to any one of claims 1 to 9, characterized in that: The following steps are involved: (1) Place 85-90% of polylactic acid, PBAT, compatibilizer, lubricant and flame retardant in a drying oven, dry at 70-80°C for 6-8 hours, and premix for 5-10 minutes to obtain a first mixture; (2) Premixing the composite anti-aging agent with 10-15% polylactic acid for 3-5 minutes to obtain a second mixture; (3) Premixing the first mixed material and the second mixed material for 2-3 minutes, adding them into a twin-screw extruder, setting the temperature to 160-190°C and the screw speed to 80-120 r / min, and melt blending to obtain a molten material; (4) The molten material is extruded, granulated and blow-molded to obtain anti-aging plastic packaging material.

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