Degradable material as well as preparation method and application thereof

Abstract

The invention discloses a degradable material as well as a preparation method and application thereof, and belongs to the technical field of packaging materials. The invention relates to a degradable material which comprises polylactic acid, polycaprolactone and a nano montmorillonite / chitosan filler, the nano-montmorillonite / chitosan filler is obtained by the following method: dissolving nano-montmorillonite to obtain a nano-montmorillonite suspension, adjusting the pH value of the nano-montmorillonite suspension with acid, performing steam condensation reflux on the nano-montmorillonite suspension after the pH value is adjusted, and performing water bath heating reaction to obtain acid modified nano-montmorillonite; fully mixing chitosan powder with an acetic acid solution to prepare a chitosan solution, adding the acid-modified nano-montmorillonite into the chitosan solution, and stirring and reacting at room temperature to obtain the nano-montmorillonite / chitosan filler. The antibacterial packaging material is applied to the aspect of product outer packaging, solves the problem of poor barrier property of an existing packaging material, and has the characteristics of high barrier property, good toughness and processability and antibacterial property.

Description

Technical Field

[0001] The present invention belongs to the technical field of packaging materials, and particularly relates to a high-barrier biodegradable material, a preparation method thereof, and an application thereof. Background Art

[0002] With the formulation of various environmental protection regulations and the improvement of people's environmental protection awareness, more and more materials are developing towards greenization. Biodegradable materials can replace ordinary plastic products and reduce the environmental pollution caused by plastics. In the packaging field, it is generally required that packaging materials have a certain ability to block oxygen and water vapor. Therefore, it is particularly important to prepare high-barrier biodegradable materials.

[0003] Chinese Patent CN105459536A discloses a five-layer co-extruded high-strength barrier antibacterial environmental protection composite film. The five-layer co-extruded high-strength barrier antibacterial environmental protection composite film from the outside to the inside is a polylactic acid / polycaprolactone composite film, a polylactic acid-starch composite film I, a polylactic acid / EVOH / POSS / layered montmorillonite composite film, a polylactic acid / starch composite film II, and a polylactic acid / chitosan composite film. The obtained composite film has high strength and toughness, good barrier properties, and certain antibacterial effects. However, the above composite film is formed by multi-layer melt co-extrusion, which requires higher equipment and complex processes. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the technical problem to be solved by the present invention is the poor barrier property of existing packaging materials, and a degradable material with high barrier property, good toughness and processability, and antibacterial property, a preparation method thereof, and an application thereof are proposed.

[0005] To solve the above technical problem, the technical solution adopted by the present invention is as follows:

[0006] On the one hand, the present invention discloses a degradable material, which includes polylactic acid, polycaprolactone, and nano-montmorillonite / chitosan filler; the nano-montmorillonite / chitosan filler is obtained by an acid-modified nano-montmorillonite preparation step and a nano-montmorillonite / chitosan filler preparation step;

[0007] The acid-modified nano-montmorillonite preparation step includes: dissolving nano-montmorillonite to obtain a nano-montmorillonite suspension, adjusting the pH of the nano-montmorillonite suspension with an acid, performing steam condensation reflux on the nano-montmorillonite suspension after adjusting the pH, and then performing a water bath heating reaction to obtain acid-modified nano-montmorillonite;

[0008] The nano-montmorillonite / chitosan filler preparation step includes: fully mixing chitosan powder with an acetic acid solution to prepare a chitosan solution, adding acid-modified nano-montmorillonite to the chitosan solution, and stirring and reacting at room temperature to obtain nano-montmorillonite / chitosan filler.

[0009] In some embodiments, the preparation steps of the acid-modified nanometer montmorillonite include: dissolving the nanometer montmorillonite to obtain a nanometer montmorillonite suspension, adjusting the pH of the nanometer montmorillonite suspension to 3-5 with hydrochloric acid, subjecting the nanometer montmorillonite suspension with adjusted pH to steam condensation reflux, heating and reacting in a water bath at 80 °C, cooling, centrifuging, washing, and drying at 75-85 °C the reaction product to obtain the acid-modified nanometer montmorillonite.

[0010] In some embodiments, the preparation steps of the nanometer montmorillonite / chitosan filler include: fully mixing chitosan powder with acetic acid solution to prepare a chitosan solution with a mass fraction of 0.1-5%, adding the acid-modified nanometer montmorillonite to the chitosan solution, stirring and reacting at room temperature, centrifuging, washing, and drying at 55-65 °C to obtain the nanometer montmorillonite / chitosan filler.

[0011] In some embodiments, in the preparation steps of the nanometer montmorillonite / chitosan filler, the mass ratio of the nanometer montmorillonite to the chitosan is selected from any value in 5-15:1.

[0012] In some embodiments, the mass fraction of the nanometer montmorillonite suspension is selected from any value in 1-15%.

[0013] In some embodiments, by mass parts, it includes 55-95 parts of polylactic acid, 5-45 parts of polycaprolactone, 0.5-5 parts of compatibilizer, 0.1-1 part of antioxidant, and 5-20 parts of modified filler; the modified filler is obtained by modifying the nanometer montmorillonite / chitosan filler with a modifier.

[0014] In some embodiments, the compatibilizer is selected from one or two of polyepoxy oligomers, lysine diisocyanate, lysine triisocyanate, tributyl citrate, and ethylene-methyl acrylate-glycidyl methacrylate; the antioxidant is selected from at least one of antioxidant 1010 and antioxidant 1076; the modifier is selected from one or several of cetyltrimethylammonium bromide, γ-glycidyletheroxypropyltrimethoxysilane, octadecyldimethylbenzylammonium chloride, and 3-aminopropyldimethylethoxysilane.

[0015] On the other hand, the present invention discloses a preparation method of the degradable material of any of the above technical solutions, including: performing high-speed mixing on the dried polylactic acid, polycaprolactone, compatibilizer, antioxidant, and modified filler, then performing melt blending, extrusion cooling, and pelletizing to obtain a composite material; performing blow molding on the composite material to form a film to obtain the degradable material.

[0016] In some embodiments, the extrusion temperature is selected from any value in 175-190 °C, and the screw speed is selected from any value in 300-400 r / min.

[0017] The present invention also discloses the application of the degradable material of any of the above technical solutions in the field of product packaging.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] The present invention provides a degradable material, which adopts a nano-montmorillonite / chitosan filler. Poly(lactic acid) has poor toughness, and the addition of the filler will cause a sharp decline in its processability. While poly(ε-caprolactone) has good toughness, excellent processability and biodegradability. After being mixed with poly(lactic acid), it can improve the toughness and processability of poly(lactic acid). At the same time, by modifying nano-montmorillonite in an acidic environment and grafting it with chitosan rich in functional groups to prepare a high-barrier antibacterial filler, the number of active reaction sites can be effectively increased, thereby significantly enhancing the compatibility between nano-montmorillonite and the polymer matrix, achieving good dispersion in the polymer matrix, endowing the material with good barrier properties and certain antibacterial properties at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural diagram of the high-barrier biodegradable material provided by the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The technical solutions in the specific embodiments of the present invention will be described in detail and completely below. Obviously, the described embodiments are only partial specific embodiments of the overall technical solution of the present invention, rather than all embodiments. Based on the overall concept of the present invention, all other embodiments obtained by those of ordinary skill in the art fall within the protection scope of the present invention.

[0022] On the one hand, the present invention discloses a degradable material, including poly(lactic acid), poly(ε-caprolactone) and nano-montmorillonite / chitosan filler. Poly(lactic acid) is a widely used biodegradable material with excellent mechanical properties. However, it has poor toughness and processability. After the addition of nano-montmorillonite / chitosan filler, the processability of poly(lactic acid) will drop sharply. While poly(ε-caprolactone) has good toughness, excellent processability and biodegradability. After being mixed with poly(lactic acid), it can improve the toughness and processability of poly(lactic acid), thereby avoiding the decline of the overall performance of the degradable material caused by the addition of nano-montmorillonite / chitosan filler.

[0023] The nano-montmorillonite / chitosan filler is obtained from the preparation steps of acid-modified nano-montmorillonite and the preparation steps of nano-montmorillonite / chitosan filler. The preparation steps of acid-modified nano-montmorillonite include: dissolving nano-montmorillonite to obtain a nano-montmorillonite suspension, adjusting the pH of the nano-montmorillonite suspension with an acid, performing steam condensation reflux on the nano-montmorillonite suspension after pH adjustment, and then carrying out a water bath heating reaction to obtain acid-modified nano-montmorillonite; the preparation steps of nano-montmorillonite / chitosan filler include: fully mixing chitosan powder with acetic acid solution to prepare a chitosan solution, adding acid-modified nano-montmorillonite to the chitosan solution, and stirring and reacting at room temperature to obtain nano-montmorillonite / chitosan filler.

[0024] Nano-montmorillonite has excellent properties, rich sources, and low prices, and can significantly improve the barrier properties and mechanical properties of polymers. However, its compatibility with polymer matrix materials is poor, which greatly limits its application. The above technical solution modifies nano-montmorillonite in an acidic environment and carries out a grafting reaction with chitosan rich in functional groups to prepare a high-barrier antibacterial filler, which can effectively increase the number of active reaction sites, thus significantly improving the compatibility between nano-montmorillonite and polymer matrix, achieving good dispersion in the polymer matrix, and endowing the material with good barrier properties while having certain antibacterial properties.

[0025] In some embodiments, the preparation steps of acid-modified nano-montmorillonite include: dissolving nano-montmorillonite to obtain a nano-montmorillonite suspension, adjusting the pH of the nano-montmorillonite suspension to 3-5 with hydrochloric acid, performing steam condensation reflux on the nano-montmorillonite suspension after pH adjustment, carrying out a water bath heating reaction at 80 °C, cooling, centrifuging, washing the reaction product, and drying at 75-85 °C to obtain acid-modified nano-montmorillonite. In some of these embodiments, the nano-montmorillonite suspension after pH adjustment is sealed with plastic wrap and the plastic wrap is pricked with a needle to enable steam condensation reflux. The reason for this technical solution to limit the pH of the nano-montmorillonite suspension to 3-5 with hydrochloric acid is that chitosan has higher solubility in an acidic environment, can expose more translation sites, improve the reaction activity, and the structural stability of chitosan is higher in an acidic environment, which is beneficial to the subsequent reaction. The temperature of the water bath heating reaction is also limited because too high a temperature will cause the cleavage of chitosan and a decrease in molecular weight, resulting in poor solubility and film-forming properties; while too low a temperature will reduce the reaction activity. Drying at 75-85 °C to obtain acid-modified nano-montmorillonite is because the lamellar structure of nano-montmorillonite will not be damaged at this temperature and the aggregation of particles can be inhibited, thus achieving the high barrier properties of the film. In addition, efficient removal of moisture and solvents can be achieved at this temperature, improving the preparation efficiency.

[0026] In some embodiments, the preparation steps of the nano-montmorillonite / chitosan filler include: fully mixing chitosan powder with acetic acid solution to prepare a chitosan solution with a mass fraction of 0.1-5%, adding acid-modified nano-montmorillonite to the chitosan solution, stirring and reacting at room temperature, centrifuging, washing, and drying at 55-65°C to obtain the nano-montmorillonite / chitosan filler. This technical solution defines the preparation of a chitosan solution with a mass fraction of 0.1-5% using acetic acid solution instead of water or other solutions because chitosan has higher solubility, more stable structure, and higher reactivity in an acidic environment. It can be understood that the mass fraction of the chitosan solution can also be 1%, 2%, 3%, 4%, or any point value within this range.

[0027] In some embodiments, in the preparation steps of the nano-montmorillonite / chitosan filler, the mass ratio of nano-montmorillonite to chitosan is selected from any value in the range of 5-15:1. This technical solution defines the mass ratio of nano-montmorillonite to chitosan because montmorillonite is the key to achieving high barrier properties of the material, and its price is relatively low, which can also improve the mechanical properties of the matrix material. Chitosan plays a more important role in modification, making montmorillonite more evenly dispersed and improving the binding ability between montmorillonite and the matrix material. Therefore, the selection of the mass ratio is an optimized result considering comprehensive functional requirements, dispersion feasibility, and economy. It can be understood that the mass ratio of nano-montmorillonite to chitosan can also be 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, or any point value ratio within this range.

[0028] In some embodiments, the mass fraction of the nano-montmorillonite suspension is selected from any value in the range of 1-15%. This technical solution defines the mass fraction of the nano-montmorillonite suspension because too high a suspension concentration will cause the interlayer spacing of nano-montmorillonite to shrink, the van der Waals force to increase significantly, resulting in stacking or agglomeration. At the same time, as the suspension concentration increases, the viscosity will also increase sharply, leading to a decline in processing performance. It can be understood that the mass fraction of the nano-montmorillonite suspension can also be 2%, 4%, 6%, 8%, 10%, 12%, 14%, or any point value within this range.

[0029] In some embodiments, by mass, it includes 55-95 parts of polylactic acid, 5-45 parts of polycaprolactone, 0.5-5 parts of compatibilizer, 0.1-1 part of antioxidant, and 5-20 parts of modified filler; the modified filler is obtained by modifying the nano-montmorillonite / chitosan filler with a modifier. As Figure 1As shown, under the action of the compatibilizer, a network structure is formed among the filler, polycaprolactone, and polylactic acid, which can significantly improve the tensile strength of the material. It can be understood that the dosage of polylactic acid can also be 60, 70, 80, 90 parts and any point value within this range, the dosage of polycaprolactone can also be 10, 20, 30, 40 parts and any point value within this range, the dosage of the compatibilizer can also be 1, 2, 3, 4 parts and any point value within this range, the dosage of the antioxidant can also be 0.2, 0.4, 0.6, 0.8 parts and any point value within this range, and the dosage of the modified filler can also be 7, 9, 11, 13, 15, 17, 10 parts and any point value within this range.

[0030] In some embodiments, the compatibilizer is selected from one or two of polyfunctional epoxy oligomers, lysine diisocyanate, lysine triisocyanate, tributyl citrate, and ethylene-methyl acrylate-glycidyl methacrylate; the antioxidant is selected from at least one of antioxidant 1010 and antioxidant 1076; the modifier is selected from one or several of cetyltrimethylammonium bromide, γ-glycidyletheroxypropyltrimethoxysilane, octadecyldimethylbenzylammonium chloride, and 3-aminopropyldimethylethoxysilane. In some embodiments, the addition ratio of the compatibilizer is 0.1-5% of the matrix material.

[0031] On the other hand, the present invention discloses a preparation method of the degradable material of any of the above technical solutions, including: performing high-speed mixing on dry polylactic acid, polycaprolactone, compatibilizer, antioxidant, and modified filler, then performing melt blending, extrusion cooling, and pelletizing to obtain a composite material; performing blow molding on the composite material to form a film to obtain a degradable material.

[0032] In some embodiments, the extrusion temperature is selected from any value in the range of 175-190°C, and the screw speed is selected from any value in the range of 300-400 r / min; the blow molding process conditions are: the temperatures of the three sections of the extruder are 220, 230, and 240°C respectively, the temperature of the diverter zone is 240°C, the temperature of the die body zone is 230°C, the main screw speed of the host is 10-30 r / min, and the traction speed is 6 mm / min.

[0033] The present invention also discloses the application of the degradable material of any of the above technical solutions in the field of product packaging. This degradable material has excellent barrier properties and biodegradability, meets the usage requirements of product outer packaging, and also has the characteristics of environmental protection.

[0034] In order to introduce the degradable material, its preparation method, and application provided by the embodiments of the present invention more clearly and in detail, the following will be described in combination with specific embodiments.

[0035] Example 1

[0036] A PLA / PCL composite material is prepared from 80 parts of PLA (polylactic acid), 20 parts of PCL (polycaprolactone), 2 parts of compatibilizer, 0.5 part of antioxidant, and 5 parts of modified filler.

[0037] (1) Preparation of nano-montmorillonite / chitosan modified filler:

[0038] Add 100 g of nano-montmorillonite into 1 L of deionized water, adjust the pH to 3 - 5 with hydrochloric acid, seal it with plastic wrap and puncture it with needles to allow steam to condense and reflux; then transfer the container to a water bath at 80 °C and stir for 4 hours. After cooling, centrifuge, remove the supernatant, wash the precipitate with deionized water 5 times, place the obtained product in an oven at 80 °C and dry it overnight, then take it out for standby.

[0039] Add 10 g of chitosan powder into a beaker, pour 1.1 L of the prepared 1% acetic acid solution into the beaker, stir well to prepare a 0.5% chitosan solution. At the same time, add 100 g of hydrochloric acid-modified nano-montmorillonite into it, and transfer the beaker to a magnetic stirrer, and stir evenly at room temperature for 6 h. Centrifuge the obtained mixture several times and wash the precipitate with deionized water, discard the supernatant and transfer the precipitate to be dried at 60 °C to constant weight.

[0040] (2) Preparation of the composite material:

[0041] First, dry PLA at 80 °C for 10 h and PCL at 50 °C for 8 h. Add 1.6 Kg of PLA, 0.4 Kg of PCL, 0.04 Kg of compatibilizer, 0.01 Kg of antioxidant, and 0.1 Kg of nano-montmorillonite / chitosan modified filler into a high-speed mixer, mix and stir for 20 min, carry out melt blending, extrusion and cooling, and then pelletize. The extrusion temperature is set at 175 - 190 °C, and the screw speed is 300 - 400 r / min. Then use a blown film machine to blow it into a film to obtain the high-barrier biodegradable material. The blown film process conditions are as follows: the temperatures of the three sections of the extruder are 220 °C, 230 °C, and 240 °C respectively, the temperature of the diverter zone is 240 °C, the temperature of the die body zone is 230 °C, the main machine screw speed is 10 - 30 r / min, and the traction speed is 6 mm / min.

[0042] Example 2

[0043] A PLA / PCL composite material is prepared from 70 parts of PLA, 30 parts of PCL, 3 parts of compatibilizer, 0.5 part of antioxidant, and 5 parts of modified filler.

[0044] (1) Preparation of nano-montmorillonite / chitosan modified filler:

[0045] Add 100 g of nano-montmorillonite to 1 L of deionized water and adjust the pH to 3 - 5 with hydrochloric acid. Seal it with plastic wrap and puncture it with needles to allow steam to condense and reflux. Then transfer the container to a water bath at 80 °C and stir for 4 hours. After cooling, centrifuge to remove the supernatant. Wash the precipitate 5 times with deionized water. Place the obtained product in an oven at 80 °C and dry it overnight, then take it out for standby.

[0046] Add 10 g of chitosan powder to a beaker. Pour 1.1 L of the prepared 1% acetic acid solution into the beaker and stir well to prepare a 0.5% chitosan solution. At the same time, add 100 g of hydrochloric acid-modified nano-montmorillonite to it, and transfer the beaker to a magnetic stirrer and stir evenly at room temperature for 6 h. Centrifuge the obtained mixture several times and wash the precipitate with deionized water. Discard the supernatant and transfer the precipitate to be dried at 60 °C to constant weight.

[0047] (2) Preparation of the composite material:

[0048] First, dry PLA at 80 °C for 10 h and PCL at 50 °C for 8 h. Add 1.4 Kg of PLA, 0.6 Kg of PCL, 0.06 Kg of compatibilizer, 0.01 Kg of antioxidant, and 0.1 Kg of nano-montmorillonite / chitosan modified filler to a high-speed mixer, mix and stir for 20 min, conduct melt blending, extrusion and cooling, and then pelletize. The extrusion temperature is set at 175 - 190 °C, and the screw speed is 300 - 400 r / min. Then use a blown film machine to blow it into a film to obtain the high-barrier biodegradable material. The blown film process conditions are as follows: the temperatures of the three sections of the extruder are 220 °C, 230 °C, and 240 °C respectively, the temperature of the diverter zone is 240 °C, the temperature of the die body zone is 230 °C, the main engine screw speed is 10 - 30 r / min, and the traction speed is 6 mm / min.

[0049] Example 3

[0050] A PLA / PCL composite material is prepared from 60 parts of PLA, 40 parts of PCL, 4 parts of compatibilizer, 0.5 part of antioxidant, and 5 parts of modified filler.

[0051] (1) Preparation of nano-montmorillonite / chitosan modified filler:

[0052] Add 100 g of nano-montmorillonite to 1 L of deionized water and adjust the pH to 3 - 5 with hydrochloric acid. Seal it with plastic wrap and puncture it with needles to allow steam to condense and reflux. Then transfer the container to a water bath at 80 °C and stir for 4 hours. After cooling, centrifuge to remove the supernatant. Wash the precipitate 5 times with deionized water. Place the obtained product in an oven at 80 °C and dry it overnight, then take it out for standby.

[0053] Add 10 g of chitosan powder to a beaker, pour 1.1 L of the prepared 1% acetic acid solution into the beaker, stir well to prepare a 0.5% chitosan solution. At the same time, add 100 g of nano-montmorillonite modified with hydrochloric acid, and transfer the beaker to a magnetic stirrer, and stir evenly at room temperature for 6 h. Centrifuge the obtained mixture several times and wash the precipitate with deionized water, discard the supernatant and transfer the precipitate to be dried at 60 °C to constant weight.

[0054] (2) Preparation of the composite material:

[0055] First, dry PLA at 80 °C for 10 h and dry PCL at 50 °C for 8 h. Add 1.2 Kg of PLA, 0.8 Kg of PCL, 0.08 Kg of compatibilizer, 0.01 Kg of antioxidant, and 0.1 Kg of nano-montmorillonite / chitosan modified filler to a high-speed mixer, mix and stir for 20 min, carry out melt blending, extrusion and cooling, and then pelletize. The extrusion temperature is set at 175 - 190 °C, and the screw speed is 300 - 400 r / min. Then use a blown film machine to blow it into a film to obtain the high-barrier biodegradable material. The blown film process conditions are as follows: the temperatures of the three sections of the extruder are 220 °C, 230 °C, and 240 °C respectively, the temperature of the diverter zone is 240 °C, the temperature of the die body zone is 230 °C, the main engine screw speed is 10 - 30 r / min, and the traction speed is 6 mm / min.

[0056] Example 4

[0057] A PLA / PCL composite material is prepared from 70 parts of PLA, 30 parts of PCL, 3 parts of compatibilizer, 0.5 parts of antioxidant, and 8 parts of modified filler.

[0058] (1) Preparation of nano-montmorillonite / chitosan modified filler:

[0059] Add 160 g of nano-montmorillonite to 1.6 L of deionized water and adjust the pH to 3 - 5 with hydrochloric acid. Seal it with plastic wrap and prick holes with a needle to allow steam to condense and reflux; then transfer the container to an 80 °C water bath and stir for 4 hours. After cooling, centrifuge to remove the supernatant, wash the precipitate with deionized water 5 times, and place the obtained product in an 80 °C oven to dry overnight and then take it out for standby.

[0060] Add 16 g of chitosan powder to a beaker, pour 1.6 L of the prepared 1% acetic acid solution into the beaker, stir well to prepare a 0.5% chitosan solution. At the same time, add 160 g of nano-montmorillonite modified with hydrochloric acid, and transfer the beaker to a magnetic stirrer, and stir evenly at room temperature for 6 h. Centrifuge the obtained mixture several times and wash the precipitate with deionized water, discard the supernatant and transfer the precipitate to be dried at 60 °C to constant weight.

[0061] (2) Preparation of the composite material:

[0062] First, dry PLA at 80 °C for 10 h and PCL at 50 °C for 8 h. Then, add 1.4 Kg of PLA, 0.6 Kg of PCL, 0.06 Kg of compatibilizer, 0.01 Kg of antioxidant, and 0.16 Kg of nano-montmorillonite / chitosan modified filler into a high-speed mixer, mix and stir for 20 min, conduct melt blending, extrusion cooling, and then granulate. The extrusion temperature is set at 175 - 190 °C, and the screw speed is 300 - 400 r / min. Then, use a blown film machine to blow it into a film to obtain the high-barrier biodegradable material. The blown film process conditions are as follows: the temperatures of the three sections of the extruder are 220 °C, 230 °C, and 240 °C respectively, the temperature of the diverter zone is 240 °C, the temperature of the die body zone is 230 °C, the main engine screw speed is 10 - 30 r / min, and the traction speed is 6 mm / min.

[0063] Example 5

[0064] A PLA / PCL composite material is prepared from 70 parts of PLA, 30 parts of PCL, 3 parts of compatibilizer, 0.5 part of antioxidant, and 3 parts of modified filler.

[0065] (1) Preparation of nano-montmorillonite / chitosan modified filler:

[0066] Add 60 g of nano-montmorillonite into 0.6 L of deionized water and adjust the pH to 3 - 5 with hydrochloric acid. Seal it with plastic wrap and prick holes with needles to allow steam to condense and reflux. Then, transfer the container to a water bath at 80 °C and stir for 4 hours. After cooling, centrifuge to remove the supernatant. Wash the precipitate 5 times with deionized water, and place the obtained product in an oven at 80 °C to dry overnight and then take it out for standby.

[0067] Add 6 g of chitosan powder into a beaker, pour 0.6 L of the prepared 1% acetic acid solution into the beaker, stir well to prepare a 0.5% chitosan solution. At the same time, add 60 g of hydrochloric acid-modified nano-montmorillonite into it, and transfer the beaker to a magnetic stirrer and stir evenly at room temperature for 6 h. Centrifuge the obtained mixture several times and wash the precipitate with deionized water. Discard the supernatant and transfer the precipitate to be dried at 60 °C to constant weight.

[0068] (2) Preparation of the composite material:

[0069] First, dry PLA at 80 °C for 10 h and PCL at 50 °C for 8 h. Add 1.4 Kg of PLA, 0.6 Kg of PCL, 0.06 Kg of compatibilizer, 0.01 Kg of antioxidant, and 0.06 Kg of nano-montmorillonite / chitosan modified filler into a high-speed mixer, mix and stir for 20 min, then carry out melt blending, extrusion cooling and pelletizing. The extrusion temperature is set at 175 - 190 °C, and the screw speed is 300 - 400 r / min. Then use a blown film machine to blow it into a film to obtain the high-barrier biodegradable material. The blown film process conditions are as follows: the temperatures of the three sections of the extruder are 220 °C, 230 °C, and 240 °C respectively, the temperature of the diverter zone is 240 °C, the temperature of the die body zone is 230 °C, the main machine screw speed is 10 - 30 r / min, and the traction speed is 6 mm / min.

[0070] Comparative Example 1

[0071] A PLA / PCL composite material is prepared from 70 parts of PLA, 30 parts of PCL, 3 parts of compatibilizer, 0.5 parts of antioxidant, and 5 parts of nano-montmorillonite.

[0072] Dry PLA at 80 °C for 10 h and PCL at 50 °C for 8 h. Add 1.4 Kg of PLA, 0.6 Kg of PCL, 0.06 Kg of compatibilizer, 0.01 Kg of antioxidant, and 0.1 Kg of nano-montmorillonite into a high-speed mixer, mix and stir for 20 min, then carry out melt blending, extrusion cooling and pelletizing. The extrusion temperature is set at 175 - 190 °C, and the screw speed is 300 - 400 r / min. Then use a blown film machine to blow it into a film to obtain the material. The blown film process conditions are as follows: the temperatures of the three sections of the extruder are 220 °C, 230 °C, and 240 °C respectively, the temperature of the diverter zone is 240 °C, the temperature of the die body zone is 230 °C, the main machine screw speed is 10 - 30 r / min, and the traction speed is 6 mm / min.

[0073] Comparative Example 2

[0074] A PLA / PCL composite material is prepared from 70 parts of PLA, 30 parts of PCL, 3 parts of compatibilizer, and 0.5 parts of antioxidant.

[0075] First, dry PLA at 80°C for 10 h and PCL at 50°C for 8 h. Then, add 1.4 Kg of PLA, 0.6 Kg of PCL, 0.06 Kg of compatibilizer, and 0.01 Kg of antioxidant into a high-speed mixer, mix and stir for 20 min, conduct melt blending, extrusion cooling, and then pelletize. The extrusion temperature is set at 175 - 190°C, and the screw speed is 300 - 400 r / min. Then, use a blown film machine to blow the material into a film. The blown film process conditions are as follows: the temperatures of the three sections of the extruder are 220°C, 230°C, and 240°C respectively, the temperature of the diverter zone is 240°C, the temperature of the die body zone is 230°C, the main machine screw speed is 10 - 30 r / min, and the traction speed is 6 mm / min.

[0076] Comparative Example 3

[0077] Directly use PLA pellets to blow into a film.

[0078] Performance testing

[0079] The raw material dosages of Examples 1 - 5 and Comparative Examples 1 - 3 are shown in Table 1.

[0080] Table 1 Raw material dosages of examples and comparative examples

[0081]

[0082] The testing methods and standards are shown in Table 2.

[0083] Table 2 Testing methods and standards

[0084]

[0085]

[0086] The test results of examples and comparative tests are shown in Table 3.

[0087] Table 3 Test results

[0088]

[0089] It can be found from Table 3 that the test results (tensile strength, elongation at break, tear strength, water vapor transmission rate, oxygen transmission rate) of Examples 1 - 5 are all better than those of Comparative Examples 1 - 3. In the present invention, nano-montmorillonite is modified in an acidic environment and grafted with chitosan rich in functional groups to prepare a high-barrier antibacterial filler, which can effectively increase the number of active reaction sites, thereby significantly improving the compatibility between nano-montmorillonite and the polymer matrix, achieving good dispersion in the polymer matrix, endowing the material with good barrier properties and certain antibacterial properties while ensuring the overall physical properties of the material.

Claims

1. A degradable material, characterized in that: The method comprises polylactic acid, polycaprolactone and nano-montmorillonite / chitosan filler; the nano-montmorillonite / chitosan filler is obtained by the steps of preparing acid-modified nano-montmorillonite and nano-montmorillonite / chitosan filler; The acid-modified nano-montmorillonite preparation step comprises: dissolving the nano-montmorillonite to obtain a nano-montmorillonite suspension, adjusting the pH of the nano-montmorillonite suspension with an acid, subjecting the nano-montmorillonite suspension after the pH adjustment to steam condensation and reflux, and then heating the solution in a water bath to react, thereby obtaining the acid-modified nano-montmorillonite; The preparation steps of the nano-montmorillonite / chitosan filler include: fully mixing chitosan powder and acetic acid solution to obtain chitosan solution, adding the acid-modified nano-montmorillonite to the chitosan solution, stirring and reacting at room temperature to obtain the nano-montmorillonite / chitosan filler.

2. The degradable material according to claim 1, characterized in that: The preparation steps of the acid-modified nano-montmorillonite include: dissolving the nano-montmorillonite to obtain a nano-montmorillonite suspension, adjusting the pH of the nano-montmorillonite suspension to 3-5 with hydrochloric acid, steam-condensing and refluxing the pH-adjusted nano-montmorillonite suspension, heating in a water bath at 80°C for reaction, cooling, centrifuging, washing and drying the reaction product at 75-85°C to obtain the acid-modified nano-montmorillonite.

3. The degradable material according to claim 1, characterized in that: The preparation steps of the nano-montmorillonite / chitosan filler include: fully mixing chitosan powder and acetic acid solution to obtain a chitosan solution with a mass fraction of 0.1-5%, adding the acid-modified nano-montmorillonite to the chitosan solution, stirring and reacting at room temperature, centrifuging, washing, and drying at 55-65° C. to obtain the nano-montmorillonite / chitosan filler.

4. The degradable material according to claim 1, characterized in that: In the step of preparing the nano-montmorillonite / chitosan filler, the mass ratio of the nano-montmorillonite to the chitosan is selected from any value between 5 and 15:

1.

5. The degradable material according to claim 1, characterized in that: The mass fraction of the nano-montmorillonite suspension is selected from any value between 1% and 15%.

6. The degradable material according to claim 1, characterized in that: The invention comprises, by weight, 55-95 parts of polylactic acid, 5-45 parts of polycaprolactone, 0.5-5 parts of a compatibilizer, 0.1-1 parts of an antioxidant, and 5-20 parts of a modified filler; the modified filler is obtained by modifying the nano-montmorillonite / chitosan filler with a modifier.

7. The degradable material according to claim 6, characterized in that: The compatibilizer is selected from one or two of polycyclic epoxy oligomers, lysine diisocyanate, lysine triisocyanate, tributyl citrate, and ethylene-methyl acrylate-glycidyl methacrylate; the antioxidant is selected from at least one of antioxidant 1010 and antioxidant 1076; the modifier is selected from one or more of hexadecyltrimethylammonium bromide, γ-glycidyloxypropyltrimethoxysilane, octadecyldimethylbenzyl ammonium chloride, and 3-aminopropyldimethylethoxysilane.

8. The method for preparing a degradable material according to any one of claims 1 to 7, characterized in that: include: The dried polylactic acid, polycaprolactone, compatibilizer, antioxidant and modified filler are mixed at high speed, then melt-blended, extruded, cooled and granulated to obtain a composite material; The composite material is blown into a film to obtain the degradable material.

9. The method for preparing a degradable material according to claim 8, characterized in that: The extrusion temperature is selected from any value in the range of 175-190° C., and the screw speed is selected from any value in the range of 300-400 r / min.

10. Use of the degradable material according to any one of claims 1 to 7 in the field of product packaging.

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