Bamboo-plastic packaging material and preparation method thereof

Abstract

The invention relates to the technical field of materials, and discloses a bamboo-to-plastic packaging material and a preparation method thereof, and the bamboo-to-plastic packaging material comprises the following components by weight: 60-70 parts of bamboo powder, 2-4 parts of maleic anhydride modified bamboo powder, 20-30 parts of polyethylene, and 2-3 parts of chitosan modified polyhedral oligomeric silsesquioxane. Adding the bamboo powder, the maleic anhydride modified bamboo powder, polyethylene and chitosan modified polyhedral oligomeric silsesquioxane into a double-screw extruder, blending for 10-15 minutes at the temperature of 180-185 DEG C, carrying out extrusion molding, and cooling to room temperature, so as to obtain the bamboo-to-plastic packaging material. The bamboo-instead-plastic packaging material disclosed by the invention has relatively good flame-retardant, antibacterial and stretch-proof effects.

Description

Technical Field

[0001] The invention relates to the technical field of materials, in particular to a bamboo plastic substitute packaging material and a preparation method thereof. Background Art

[0002] Plastic packaging materials are widely used in food, daily chemicals, logistics, and other fields due to their low cost and excellent processing properties. However, traditional plastic packaging materials, such as polyethylene (PE), are non-biodegradable and contribute to the generation of plastic waste. Bamboo, a fast-growing, renewable resource (maturing in 3-5 years), offers high density and strength, making it an ideal alternative to plastic. However, when bamboo powder and polyethylene (PE) are simply blended, poor interfacial compatibility results in low tensile strength, making them difficult to meet packaging material requirements. Furthermore, both materials are flammable; therefore, avoiding this problem is crucial. Summary of the Invention

[0003] (1) Technical problems solved

[0004] In view of the deficiencies in the prior art, the present invention provides a bamboo plastic substitute packaging material and a preparation method thereof, which has good flame retardant, antibacterial and tensile resistance effects.

[0005] (2) Technical solution

[0006] To achieve the above objectives, the present invention provides the following technical solution: a bamboo plastic substitute packaging material, comprising the following components by weight: 60-70 parts by weight of bamboo powder, 2-4 parts by weight of maleic anhydride modified bamboo powder, 20-30 parts by weight of polyethylene, and 2-3 parts by weight of chitosan modified cage-type silsesquioxane.

[0007] Furthermore, the preparation method of the chitosan-modified caged silsesquioxane is as follows:

[0008] S1. Add L-lysine and pyridine to N,N-dimethylformamide solvent, stir to dissolve, then add 4-vinylbenzoyl chloride. React at 25-35°C for 6-8 hours. After reaction, concentrate the solution, wash the product with methanol, and recrystallize it with ethyl acetate to obtain alkenyl-modified lysine.

[0009] S2. Adding alkenyl-modified lysine and octaepoxy cage silsesquioxane to xylene solvent, stirring to dissolve, adding tetrabutylammonium bromide, reacting at 95-110 ° C for 4-5 hours, and then distilling under reduced pressure and washing with acetone to obtain alkenyl-modified cage silsesquioxane;

[0010] S3. Chitosan was dissolved in a 1% acetic acid solution by mass, heated in a water bath at 65-70°C, and 2,3-epoxypropyltrimethylammonium chloride was added at constant pressure for 6-10 hours. After the reaction, the mixture was washed with anhydrous ethanol, dried, dialyzed, and concentrated to obtain quaternized chitosan.

[0011] S4. 1.7-1.9 mmol of quaternized chitosan and 1.74-2 mmol of acrylic acid were added to 55-65 mL of N, N-dimethylformamide solvent and stirred uniformly. 0.01-0.03 g of p-toluenesulfonic acid catalyst was then added thereto and reacted at 80-110 ° C. After completion, the reaction was carried out by vacuum distillation, filtration and drying to obtain olefinated chitosan;

[0012] S5. Add 5-7 g of alkenyl-modified cage-type silsesquioxane and 16-20 g of alkenyl chitosan to 45-55 mL of N,N-dimethylformamide solvent, dissolve, add 0.2-0.4 g of azobisisobutyronitrile initiator, heat and react for 3-5 hours, remove the solvent by distillation under reduced pressure after the reaction, filter and dry to obtain chitosan-modified cage-type silsesquioxane.

[0013] Furthermore, the usage ratio of N,N-dimethylformamide solvent, L-lysine, pyridine, and 4-vinylbenzoyl chloride in S1 is 55-65 mL: 1-1.2 mmol: 0.013-0.02 g: 2.53-2.74 mmol.

[0014] Furthermore, in the S2, the usage ratio of alkenyl-modified lysine, octaepoxy cage-type silsesquioxane, xylene solvent, and tetrabutylammonium bromide is 8.2-9 mmol: 1 mmol: 50-70 mL: 0.021-0.026 g.

[0015] Furthermore, the usage ratio of chitosan and 2,3-epoxypropyltrimethylammonium chloride in S3 is 2-2.6 mmol: 2.2-2.4 mmol.

[0016] Furthermore, the reaction time in S4 is 10-14 hours.

[0017] Furthermore, the reaction temperature in S5 is 80-90°C.

[0018] Furthermore, the preparation method of the bamboo plastic substitute packaging material is: adding bamboo powder, maleic anhydride modified bamboo powder, polyethylene, and chitosan modified cage silsesquioxane into a twin-screw extruder at a temperature of 180-185°C, blending for 10-15 minutes, extruding and molding, and cooling to room temperature to obtain the bamboo plastic substitute packaging material.

[0019] (3) Beneficial technical effects

[0020] The invention prepares the bamboo plastic substitute packaging material by adding bamboo powder, maleic anhydride modified bamboo powder, polyethylene and chitosan modified cage type silsesquioxane into a twin-screw extruder, extruding and molding the mixture, and cooling the mixture to room temperature.

[0021] In the above reaction process, the amino group in L-lysine reacts with the acyl chloride group in 4-vinylbenzoyl chloride to introduce a carboxyl group and an alkenyl group, thereby obtaining alkenyl-modified lysine; the carboxyl group in the alkenyl-modified lysine reacts with the epoxy group in the octaepoxy cage silsesquioxane to generate a hydroxyl group, thereby obtaining an alkenyl-modified cage silsesquioxane; the amino group in chitosan and the epoxy group in 2,3-epoxypropyltrimethylammonium chloride undergo a ring-opening reaction to generate a hydroxyl group, thereby obtaining quaternized chitosan, which is further esterified with the carboxyl group in acrylic acid to introduce an alkenyl group, thereby obtaining alkenylated chitosan; the alkenyl-modified cage silsesquioxane and the alkenylated chitosan undergo a polymerization reaction under the action of azobisisobutyronitrile initiator to obtain chitosan-modified cage silsesquioxane.

[0022] When heated, the silicon in chitosan-modified caged silsesquioxane forms a glassy substance on the surface, isolating material transport and energy transfer. When heated, the nitrogen produces a non-flammable gas that not only dilutes the concentration of flammable gases but also removes some heat, further limiting combustion. Furthermore, the chitosan itself possesses excellent flame retardant and antibacterial properties.

[0023] The maleic anhydride-modified bamboo powder forms chemical bonds with the polar groups of polyethylene through the anhydride groups. This also creates a hydrogen bonding network with the chitosan-modified caged silsesquioxane and the hydroxyl groups on the bamboo powder surface, improving compatibility and stretchability. The quaternary ammonium groups in the chitosan-modified caged silsesquioxane can disrupt bacterial cell membranes, leading to bacterial death and a strong antibacterial effect. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0025] Preparation of bamboo powder: fresh bamboo is cut into 30mm×30mm×5mm pieces according to the grain, dried with hot air at 60℃ until the moisture content is ≤8%; then crushed into 50-mesh bamboo powder using a grinder.

[0026] Preparation of maleic anhydride-modified bamboo powder: Bamboo powder was dried in an oven at 103°C until absolutely dry. Then, 10.00 g of bamboo powder, 30.00 g of dimethylformamide solution, and 0.60 g of maleic anhydride were weighed and mixed in a three-necked round-bottom flask. The mixture was stirred and heated to 100°C under a nitrogen atmosphere for 3 hours. After the reaction, the bamboo powder was rinsed with deionized water and acetone to remove excess solution, and then dried and ground to obtain maleic anhydride-modified bamboo powder.

[0027] Polyethylene: Low density polyethylene.

[0028] The preparation of octaepoxy cage silsesquioxane refers to "Thermosetting Resins", Volume 29, Issue 3, at the end of May 2014, document "Synthesis Research of Epoxy Cage Silsesquioxane": 2% tetramethylammonium hydroxide aqueous solution was added dropwise to isopropanol, and then a xylene solution containing KH560 was added dropwise, and the mixture was stirred and hydrolyzed at room temperature for 7 hours, and then the temperature was raised to 80°C and refluxed for 1 hour. After the reaction, the pH of the solution was adjusted to neutral with saturated brine, and stirred at room temperature for 1 hour. The solvent was then distilled off under reduced pressure and washed with acetone to obtain octaepoxy cage silsesquioxane (EP-POSS).

[0029] Example 1

[0030] S1. Add 1 mmol of L-lysine and 0.013 g of pyridine to 55 mL of N,N-dimethylformamide solvent, stir to dissolve, then add 2.53 mmol of 4-vinylbenzoyl chloride. React at 25°C for 6 h. After reaction, concentrate the solution, wash the product with methanol, and recrystallize it with ethyl acetate to obtain alkenyl-modified lysine.

[0031] S2. 8.2 mmol of alkenyl-modified lysine and 1 mmol of octaepoxy cage silsesquioxane were added to 50 mL of xylene solvent and stirred to dissolve. 0.021 g of tetrabutylammonium bromide was added and the mixture was reacted at 95°C for 4 h. After reaction, the mixture was evaporated under reduced pressure and washed with acetone to obtain alkenyl-modified cage silsesquioxane.

[0032] S3. 2 mmol of chitosan was dissolved in a 1% acetic acid solution, heated in a water bath at 65°C, and 2.2 mmol of 2,3-epoxypropyltrimethylammonium chloride was added at constant pressure. The mixture was allowed to react for 6 h. After the reaction, the mixture was washed with anhydrous ethanol, dried, dialyzed, and concentrated to obtain quaternized chitosan.

[0033] S4. 1.7 mmol of quaternized chitosan and 1.74 mmol of acrylic acid were added to 55 mL of N,N-dimethylformamide solvent and stirred uniformly. 0.01 g of p-toluenesulfonic acid catalyst was then added thereto. The reaction was carried out at 80°C for 10 h. After completion, the mixture was distilled under reduced pressure, filtered, and dried to obtain olefinated chitosan.

[0034] S5. 5 g of alkenyl-modified cage silsesquioxane and 16 g of alkenyl chitosan were added to 45 mL of N,N-dimethylformamide solvent, dissolved, and then 0.2 g of azobisisobutyronitrile initiator was added. The reaction temperature was raised to 80 ° C for 3 h. After the reaction, the solvent was distilled off under reduced pressure, filtered and dried to obtain chitosan-modified cage silsesquioxane;

[0035] S6. 60 parts by weight of bamboo powder, 2 parts by weight of maleic anhydride-modified bamboo powder, 20 parts by weight of polyethylene, and 2 parts by weight of chitosan-modified cage-type silsesquioxane were added to a twin-screw extruder at a temperature of 180°C, blended for 10 minutes, extruded, and cooled to room temperature to obtain a bamboo plastic packaging material.

[0036] Example 2

[0037] S1. Add 1.2 mmol of L-lysine and 0.02 g of pyridine to 65 mL of N,N-dimethylformamide solvent, stir to dissolve, then add 2.74 mmol of 4-vinylbenzoyl chloride. React at 35°C for 8 h. After reaction, concentrate the solution, wash the product with methanol, and recrystallize it with ethyl acetate to obtain alkenyl-modified lysine.

[0038] S2. 9 mmol of alkenyl-modified lysine and 1 mmol of octaepoxy cage silsesquioxane were added to 70 mL of xylene solvent and stirred to dissolve. 0.026 g of tetrabutylammonium bromide was then added and the mixture was reacted at 110°C for 5 h. After reaction, the mixture was evaporated under reduced pressure and washed with acetone to obtain alkenyl-modified cage silsesquioxane.

[0039] S3. 2.6 mmol of chitosan was dissolved in a 1% acetic acid solution, heated in a water bath at 70°C, and 2.4 mmol of 2,3-epoxypropyltrimethylammonium chloride was added at constant pressure. The mixture was allowed to react for 10 h. After the reaction, the mixture was washed with anhydrous ethanol, dried, dialyzed, and concentrated to obtain quaternized chitosan.

[0040] S4. 1.9 mmol of quaternized chitosan and 2 mmol of acrylic acid were added to 65 mL of N,N-dimethylformamide solvent and stirred uniformly. 0.03 g of p-toluenesulfonic acid catalyst was then added thereto. The reaction was carried out at 110°C for 14 h. After completion, the mixture was distilled under reduced pressure, filtered, and dried to obtain olefinated chitosan.

[0041] S5. 7 g of alkenyl-modified cage silsesquioxane and 20 g of alkenyl chitosan were added to 55 mL of N,N-dimethylformamide solvent, dissolved, and then 0.4 g of azobisisobutyronitrile initiator was added. The reaction temperature was raised to 90 ° C for 5 h. After the reaction, the solvent was distilled off under reduced pressure, filtered and dried to obtain chitosan-modified cage silsesquioxane;

[0042] S6. 70 parts by weight of bamboo powder, 4 parts by weight of maleic anhydride-modified bamboo powder, 30 parts by weight of polyethylene, and 3 parts by weight of chitosan-modified cage-type silsesquioxane were added to a twin-screw extruder at a temperature of 185°C, blended for 15 minutes, extruded, and cooled to room temperature to obtain a bamboo plastic packaging material.

[0043] Example 3

[0044] S1. Add 1.1 mmol of L-lysine and 0.016 g of pyridine to 60 mL of N,N-dimethylformamide solvent, stir to dissolve, then add 2.67 mmol of 4-vinylbenzoyl chloride. React at 30°C for 7 h. After reaction, concentrate the solution, wash the product with methanol, and recrystallize it with ethyl acetate to obtain alkenyl-modified lysine.

[0045] S2. 8.5 mmol of alkenyl-modified lysine and 1 mmol of octaepoxy cage silsesquioxane were added to 60 mL of xylene solvent and stirred to dissolve. 0.023 g of tetrabutylammonium bromide was added and the mixture was reacted at 100 ° C for 4.5 h. After the reaction, the mixture was evaporated under reduced pressure and washed with acetone to obtain alkenyl-modified cage silsesquioxane.

[0046] S3. 2.4 mmol of chitosan was dissolved in a 1% acetic acid solution, heated in a water bath at 68°C, and 2.3 mmol of 2,3-epoxypropyltrimethylammonium chloride was added at constant pressure. The mixture was allowed to react for 8 h. After the reaction, the mixture was washed with anhydrous ethanol, dried, dialyzed, and concentrated to obtain quaternized chitosan.

[0047] S4. 1.8 mmol of quaternized chitosan and 1.86 mmol of acrylic acid were added to 60 mL of N,N-dimethylformamide solvent and stirred uniformly. 0.02 g of p-toluenesulfonic acid catalyst was then added thereto. The reaction was carried out at 90°C for 12 h. After completion, the mixture was distilled under reduced pressure, filtered, and dried to obtain olefinated chitosan.

[0048] S5. 6 g of alkenyl-modified cage silsesquioxane and 18 g of alkenyl chitosan were added to 50 mL of N,N-dimethylformamide solvent, dissolved, and then 0.3 g of azobisisobutyronitrile initiator was added. The reaction temperature was raised to 85 ° C for 4 h. After the reaction, the solvent was distilled off under reduced pressure, filtered and dried to obtain chitosan-modified cage silsesquioxane;

[0049] S6. 65 parts by weight of bamboo powder, 3 parts by weight of maleic anhydride-modified bamboo powder, 25 parts by weight of polyethylene, and 2.5 parts by weight of chitosan-modified cage-type silsesquioxane were added to a twin-screw extruder at a temperature of 182°C, blended for 12 minutes, extruded, and cooled to room temperature to obtain a bamboo plastic packaging material.

[0050] Comparative Example 1

[0051] Compared with Example 3, this comparative example is different in that octaepoxy cage silsesquioxane is used instead of chitosan-modified cage silsesquioxane.

[0052] Comparative Example 2

[0053] Compared with Example 3, this comparative example differs in that chitosan is used instead of chitosan to modify caged silsesquioxane.

[0054] Performance Testing

[0055] A Streptococcus aureus liquid at a concentration of 2×108 CFU / mL was added to a sterilized culture dish as the test strain. Solid agar medium was then added and dissolved, cooled to 45°C, and poured into the culture dishes, with 20 mL poured into each dish with an inner diameter of 10 cm. Materials from the examples of the present invention and the comparative example (3 cm in diameter and 1 mm thick) were then placed on the culture plates and incubated in a constant temperature incubator at 37°C for 12 hours. The diameter of the inhibition zone was measured after incubation. The test results are shown in Table 1.

[0056] Table 1: Antibacterial test.

[0057] project Diameter of inhibition zone (mm) Example 1 15.1 Example 2 16.9 Example 3 16.3 Comparative Example 1 3.7 Comparative Example 2 8.6

[0058] As can be seen from Table 1, Examples 1-3 of the bamboo plastic substitute packaging material of the present invention have better antibacterial effects than Comparative Examples 1-2.

[0059] Use an oxygen index tester to test the oxygen index of the material.

[0060] The combustion level of the material is tested using a horizontal vertical combustion tester.

[0061] Table 2: Flame retardant test.

[0062] project Oxygen index (%) UL-94 Example 1 30.46 V-0 Example 2 31.27 V-0 Example 3 31.68 V-0 Comparative Example 1 23.59 V-1 Comparative Example 2 22.17 V-1

[0063] As can be seen from Table 2, Examples 1-3 of the present invention have better flame retardant effects than Comparative Examples 1-2.

[0064] The tensile properties were measured with reference to GB / T 1040.1-2018 standard using an electronic universal testing machine at a tensile rate of 50 mm / min. The specimens were 8 cm long, 2 cm wide, and 4 mm high.

[0065] Table 3: Tensile properties tested.

[0066] project Tensile properties (MPa) Example 1 31.2 Example 2 33.6 Example 3 31.5 Comparative Example 1 19.8 Comparative Example 2 17.4

[0067] As shown in Table 3, Examples 1-3 of the bamboo plastic substitute packaging material of the present invention have better stretching effects than Comparative Examples 1-2.

[0068] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0069] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

[0070] Those skilled in the art should understand that the above descriptions are only some specific embodiments of the present invention, rather than all embodiments.

Claims

1. A bamboo plastic packaging material, characterized in that: The invention comprises the following components by weight: 60-70 parts by weight of bamboo powder, 2-4 parts by weight of maleic anhydride modified bamboo powder, 20-30 parts by weight of polyethylene, and 2-3 parts by weight of chitosan modified cage-type silsesquioxane.

2. The bamboo plastic substitute packaging material according to claim 1, characterized in that: The preparation method of the chitosan modified caged silsesquioxane is as follows: S1. Add L-lysine and pyridine to N,N-dimethylformamide solvent, stir to dissolve, then add 4-vinylbenzoyl chloride. React at 25-35°C for 6-8 hours. After reaction, concentrate the solution, wash the product with methanol, and recrystallize it with ethyl acetate to obtain alkenyl-modified lysine. S2. Adding alkenyl-modified lysine and octaepoxy cage silsesquioxane to xylene solvent, stirring to dissolve, adding tetrabutylammonium bromide, reacting at 95-110 ° C for 4-5 hours, and then distilling under reduced pressure and washing with acetone to obtain alkenyl-modified cage silsesquioxane; S3. Chitosan was dissolved in a 1% acetic acid solution by mass, heated in a water bath at 65-70°C, and 2,3-epoxypropyltrimethylammonium chloride was added at constant pressure for 6-10 hours. After the reaction, the mixture was washed with anhydrous ethanol, dried, dialyzed, and concentrated to obtain quaternized chitosan. S4. 1.7-1.9 mmol of quaternized chitosan and 1.74-2 mmol of acrylic acid were added to 55-65 mL of N, N-dimethylformamide solvent and stirred uniformly. 0.01-0.03 g of p-toluenesulfonic acid catalyst was then added thereto and reacted at 80-110 ° C. After completion, the reaction was carried out by vacuum distillation, filtration and drying to obtain olefinated chitosan; S5. Add 5-7 g of alkenyl-modified cage-type silsesquioxane and 16-20 g of alkenyl chitosan to 45-55 mL of N,N-dimethylformamide solvent, dissolve, add 0.2-0.4 g of azobisisobutyronitrile initiator, heat and react for 3-5 hours, remove the solvent by distillation under reduced pressure after the reaction, filter and dry to obtain chitosan-modified cage-type silsesquioxane.

3. The bamboo plastic substitute packaging material according to claim 2, characterized in that: The usage ratio of N,N-dimethylformamide solvent, L-lysine, pyridine, and 4-vinylbenzoyl chloride in S1 is 55-65 mL: 1-1.2 mmol: 0.013-0.02 g: 2.53-2.74 mmol.

4. The bamboo plastic substitute packaging material according to claim 2, characterized in that: The usage ratio of alkenyl-modified lysine, octaepoxy cage-type silsesquioxane, xylene solvent, and tetrabutylammonium bromide in S2 is 8.2-9 mmol: 1 mmol: 50-70 mL: 0.021-0.026 g.

5. The bamboo plastic substitute packaging material according to claim 2, characterized in that: The usage ratio of chitosan and 2,3-epoxypropyltrimethylammonium chloride in S3 is 2-2.6 mmol: 2.2-2.4 mmol.

6. The bamboo plastic substitute packaging material according to claim 2, characterized in that: The reaction time in S4 is 10-14 hours.

7. The bamboo plastic substitute packaging material according to claim 2, characterized in that: The reaction temperature in S5 is 80-90°C.

8. A method for preparing the bamboo plastic substitute packaging material according to any one of claims 1 to 7, characterized in that: The preparation method of the bamboo plastic substitute packaging material comprises the following steps: adding bamboo powder, maleic anhydride modified bamboo powder, polyethylene, and chitosan modified cage silsesquioxane into a twin-screw extruder at a temperature of 180-185° C., blending for 10-15 minutes, extruding and molding, and cooling to room temperature to obtain the bamboo plastic substitute packaging material.