Bamboo fiber recyclable express environment-friendly bag and preparation method thereof

Abstract

The invention discloses a bamboo fiber recyclable express environment-friendly bag and a preparation method thereof, and belongs to the technical field of green packaging materials and sustainable logistics equipment. The environment-friendly bag is formed by melting and co-extruding modified bamboo fibers, bioactive polyolefin and aminated two-dimensional molybdenum disulfide to prepare a 60-100 [mu] m thin film and then heat-sealing the thin film. The modified bamboo fibers are prepared through alkali liquor pretreatment, ultrasonic cleaning, plasma activation and aminated MoS coating, the bioactive polyolefin is obtained through plasma grafting maleic anhydride, and aminated MoS synchronously achieves the functions of interface enhancement, lubrication and friction reduction, bacteria resistance and bacteriostasis and thermal stability improvement. The problems that a traditional plastic express bag is serious in pollution and an existing biodegradable bag is insufficient in performance are solved, and an efficient solution is provided for green transformation of the express industry.

Description

Technical Field

[0001] This invention relates to the field of green packaging materials and sustainable logistics equipment technology, and in particular to a bamboo fiber recyclable express delivery bag and its preparation method. Background Technology

[0002] With the rapid development of the express delivery, e-commerce, and modern logistics industries, my country's express delivery volume continues to climb. Currently, more than 90% of express packaging relies on petroleum-based plastic materials such as polyethylene (PE) and polypropylene (PP). These materials are derived from non-renewable fossil fuels, and each ton of these materials requires 3-5 tons of crude oil to produce. Traditional plastic express delivery bags have many drawbacks: First, they are difficult to degrade, with a degradation cycle of 200-500 years in the natural environment, causing serious "white pollution"; second, they have a low recycling rate, with actual recycling rates of less than 10% due to severe pollution and difficulty in sorting; third, they have limited mechanical properties, lacking antibacterial, wear-resistant, and heat-resistant functions, making it difficult to meet the needs of frequent handling, squeezing, and friction in express delivery; and fourth, they have a high carbon footprint, with significant carbon emissions throughout the entire process from raw material extraction to waste disposal, with each ton of traditional PE express delivery bag emitting approximately 2.8 tons of CO2. Although existing technologies attempt to replace traditional plastics with biodegradable materials such as starch-based and PLA, they generally suffer from problems such as poor mechanical strength (tensile strength ≤25MPa), high cost (3-5 times that of traditional PE bags), and difficulty in processing (narrow molding temperature range, easy degradation), failing to meet the actual needs of express delivery packaging. Therefore, this invention proposes a new type of environmentally friendly express delivery bag that combines high strength, long lifespan, easy recyclability, multi-functional integration, and sustainable sources, constructing a green circular system covering the entire life cycle of "production-use-recycling-regeneration". Summary of the Invention

[0003] The purpose of this invention is to overcome the defects of the prior art and provide a bamboo fiber recyclable express delivery bag and its preparation method. Through innovative material formulation and process, it achieves a balance between environmental protection, mechanical properties and economy.

[0004] To achieve the above objectives, this invention provides a bamboo fiber recyclable express delivery bag, comprising modified bamboo fiber, bioactive polyolefin, and aminated molybdenum disulfide, wherein the mass percentages of each component are: bamboo fiber 5-40 wt%, bioactive polyolefin 60-95 wt%, and aminated molybdenum disulfide 0.1-5 wt%. The composite material is made into a film with a thickness of 60-100μm through melt co-extrusion process. The environmentally friendly bag has a tensile strength ≥45MPa, a tear strength ≥30N / mm, and an antibacterial rate of >99.9% against Escherichia coli and Staphylococcus aureus.

[0005] Furthermore, the modified bamboo fiber is prepared by the following process: the bamboo fiber is heated to 60-80℃ at 1-3℃ / min and kept at that temperature for 60-120min in a 1-5% NaOH solution or a mixed alkaline solution containing 0.5-1.5% Na2SO3, and then ultrasonically cleaned. After treatment with atmospheric pressure plasma at a gas pressure of 10-10000Pa and a discharge power of 10-800W for 0.5-30min, it is then coated with an aminated molybdenum disulfide ethanol solution and dried.

[0006] Furthermore, the aminated two-dimensional molybdenum disulfide is prepared by introducing amino (-NH2) and thiol (-SH) functional groups onto the surface of MoS2 via a chemical grafting method, with a grafting rate of 25-35%.

[0007] Furthermore, the bioactive polyolefin is prepared by plasma-assisted grafting of maleic anhydride.

[0008] A method for preparing a bamboo fiber recyclable express delivery bag, characterized by comprising the following steps: (1) Bamboo fiber pretreatment: Add bamboo fiber to alkaline solution, heat and keep warm, and wash until neutral; (2) Bamboo fiber modification: After ultrasonic cleaning and atmospheric pressure plasma treatment, it is coated with aminated two-dimensional molybdenum disulfide ethanol solution and dried. (3) Preparation of bioactive polyolefins: maleic anhydride is grafted onto polyolefin resin via plasma; (4) Mixing and molding: Mix the components according to the ratio, melt-blend in a twin-screw extruder at 170-210℃, and heat-seal to make bags after forming film.

[0009] Further, in step (1), the alkaline solution is a NaOH solution with a mass fraction of 1-5% or a mixed alkaline solution containing 0.5-1.5% Na2SO3, with a solid-liquid ratio of 1:10-20, a heating rate of 1-3℃ / min, a holding temperature of 60-80℃, and a holding time of 60-120min.

[0010] Further, in step (2), the ultrasonic cleaning parameters are 40kHz frequency, 300W power, and cleaning time of 15-30min; the atmospheric pressure plasma treatment has a gas pressure of 10-10000Pa, a discharge power of 10-800W, and a treatment time of 0.5-30min; the concentration of the aminated two-dimensional molybdenum disulfide ethanol solution is 0.5-2wt%, the drying temperature after coating is 80-100℃, and the drying time is 1-2h.

[0011] Further, in step (3), the polyolefin resin is linear low-density polyethylene (LLDPE) or polypropylene (PP); the gas pressure for plasma-assisted grafting of maleic anhydride is 1-100 Pa, the discharge power is 4-120 W, the treatment time is 0.1-100 min, and the maleic anhydride grafting rate is 1.2-2.5%.

[0012] Furthermore, in step (4), the melt blending temperature of the twin-screw extruder is 170-210℃, the main machine speed is 10-40 rpm, the film forming method is extrusion, casting or calendering, the film thickness is 60-100μm, the heat sealing bag making temperature is 150-180℃, and the heat sealing pressure is 0.3-0.5MPa.

[0013] The beneficial effects of this invention are as follows: Outstanding environmental friendliness: It replaces part of the petroleum-based polyolefin with natural bamboo fiber (a renewable biomass resource), reducing crude oil consumption; the product's carbon footprint is lower than that of traditional PE bags, and it can be recycled or naturally degraded after disposal, reducing "white pollution" from the source.

[0014] Excellent mechanical properties: Through the interfacial reinforcement effect of aminated MoS2 and the chemical bonding between bioactive polyolefin and bamboo fiber, the product has a tensile strength ≥45MPa, tear strength ≥30N / mm, puncture resistance ≥8N, and tensile strength retention rate ≥80% after 50 cycles of use. It can meet the stringent requirements of frequent handling, compression and friction in express transportation and solve the defects of poor mechanical properties of existing starch-based and PLA bags. Multifunctional integration: Aminated MoS2 endows the product with multiple functions: reduced coefficient of friction, antibacterial rate of >99.9% against Escherichia coli and Staphylococcus aureus, and improved stability under high temperature environment, breaking through the limitation of the single function of traditional express bags.

[0015] Economically viable: Bamboo fiber raw materials are widely available and have lower costs than biodegradable materials such as PLA; the preparation process uses mature melt co-extrusion and heat sealing technologies, which are compatible with existing plastic packaging production lines, do not require large-scale equipment modifications, have high production efficiency, and have the economic foundation for large-scale promotion. Industrial spillover effect: This invention promotes the upgrading of bamboo resources from "primary processing" to "high-end packaging materials", extending the value chain of the bamboo industry; at the same time, it drives the development of upstream and downstream industries such as bamboo planting, bamboo fiber processing, and environmental protection equipment manufacturing, creating jobs and meeting the needs of regional green economic development. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 Flowchart of bamboo fiber modification; Figure 2 Flowchart for the preparation of bioactive polyolefins; Figure 3 A flowchart illustrating the entire lifecycle of eco-friendly bags. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0019] A recyclable bamboo fiber express delivery bag is composed of a composite material made of modified bamboo fiber, bioactive polyolefin and aminated molybdenum disulfide. The composite material is made into a film with a thickness of 60-100μm by melt co-extrusion process. The mass percentage of each component is: bamboo fiber 5-40wt%, bioactive polyolefin 60-95wt%, and aminated molybdenum disulfide 0.1-5wt%.

[0020] The modified bamboo fiber is prepared through a three-step process: "alkali pretreatment - ultrasonic cleaning - atmospheric pressure plasma activation". First, it is heated to 60-80℃ in a 1-5% NaOH solution (solid-liquid ratio 1:10-20) at 1-3℃ / min and held for 60-120min to remove lignin and pectin from the surface of the bamboo fiber. Then, it is ultrasonically cleaned at 40kHz and 300W for 15-30min to remove residual impurities. Finally, it is treated with atmospheric pressure plasma at a gas pressure of 10-10000Pa and a discharge power of 10-800W for 0.5-30min to increase the number of active groups on the fiber surface (hydroxyl content increases by 40-60%) and enhance the interfacial bonding force with the polymer matrix. The aminated two-dimensional molybdenum disulfide was prepared by chemical grafting with silane coupling agent KH-792, introducing amino (-NH2) and thiol (-SH) functional groups onto the surface of MoS2 sheets, with a grafting rate of 25-35%. This not only enhances the compatibility between bamboo fiber and polyolefin, but also endows the composite material with multiple functions such as lubrication and friction reduction, antibacterial and bacteriostatic properties (antibacterial rate against Escherichia coli and Staphylococcus aureus >99.9%), and improved thermal stability (thermal decomposition temperature increased by 20-30℃). The bioactive polyolefin is prepared by plasma-assisted grafting of maleic anhydride: under a gas pressure of 1-100 Pa and a discharge power of 4-120 W, the polyolefin is placed in a plasma environment containing maleic anhydride for 0.1-100 min, and the maleic anhydride grafting rate reaches 1.2-2.5%, forming a polyolefin with reactive sites, which can form chemical bonds with the hydroxyl groups on the surface of modified bamboo fiber, further improving the mechanical properties of the composite material. This invention also provides a method for preparing the above-mentioned bamboo fiber recyclable express delivery bag, comprising the following steps: Bamboo fiber pretreatment: Add bamboo fiber (particle size ≤100 mesh) to a 1-5% NaOH solution or a mixed alkaline solution containing 0.5-1.5% Na2SO3, with a solid-liquid ratio of 1:10-20, heat to 60-80℃ at 1-3℃ / min, keep warm for 60-120min, and then wash with deionized water until neutral; Bamboo fiber modification: The pretreated bamboo fiber is ultrasonically cleaned at 40kHz and 300W for 15-30 minutes, dried, and then placed in an atmospheric pressure plasma device for 0.5-30 minutes at a gas pressure of 10-10000Pa and a discharge power of 10-800W to obtain activated bamboo fiber; Aminated molybdenum disulfide is dispersed in an ethanol solution (concentration 0.5-2wt%), sprayed onto the surface of the activated bamboo fiber, and dried at 80-100℃ for 1-2 hours to form coated modified bamboo fiber; Preparation of bioactive polyolefins: Polyolefin resin (LLDPE or PP) is placed in a vacuum chamber, maleic anhydride vapor is introduced, and it is treated for 0.1-100 min at a gas pressure of 1-100 Pa and a discharge power of 4-120 W to achieve maleic anhydride grafting and obtain bioactive polyolefins. Mixing and molding: Modified bamboo fiber, bioactive polyolefin and additionally added aminated two-dimensional molybdenum disulfide are mixed according to the formula and fed into a twin-screw extruder. The mixture is melt-blended at a temperature of 170-210℃ and a main machine speed of 10-40 rpm. The mixture is then extruded, cast or calendered into a film (thickness 60-100μm), and then heat-sealed into bags at a temperature of 150-180℃ and a pressure of 0.3-0.5MPa. Example 1 Bamboo fiber pretreatment: Take 100g of bamboo fiber powder (particle size 80 mesh), add 3% NaOH solution (solid-liquid ratio 1:15), heat to 70℃ at 2℃ / min, keep warm for 90min, and wash with deionized water until neutral; Bamboo fiber modification: After ultrasonic cleaning at 40kHz and 300W for 20 minutes and drying at 105℃, the bamboo fiber was placed in an atmospheric pressure air plasma device with a pressure of 5000Pa and a power of 300W for 10 minutes. Aminated molybdenum disulfide (grafting rate 30%) was dispersed in ethanol (concentration 1wt%) and sprayed onto the surface of activated bamboo fiber. The bamboo fiber was then dried at 90℃ for 1.5 hours to obtain modified bamboo fiber. Preparation of bioactive polyolefin: Take LLDPE resin, place it in a vacuum chamber, introduce maleic anhydride vapor, set the pressure to 50 Pa and the power to 60 W, treat for 30 min, the maleic anhydride grafting rate is 1.8%, and bioactive LLDPE is obtained. Mixing and molding: Modified bamboo fiber, bioactive LLDPE and aminated molybdenum disulfide were mixed in a mass ratio of 35:64.5:0.5 and fed into a twin-screw extruder. The mixture was melt-blended at 190°C and 30 rpm, cast into a film (80 μm thick), and then heat-sealed into bags at 160°C and 0.4 MPa. Performance test results: tensile strength 48.6MPa, tear strength 32.4N / mm, puncture resistance 9.2N, antibacterial rate against Escherichia coli 99.95%, antibacterial rate against Staphylococcus aureus 99.96%, tensile strength retention rate after 53 cycles 82%, carbon footprint 0.42 tons CO2 / ton of product. Example 2 Bamboo fiber pretreatment: Take 80g of bamboo fiber powder (particle size 100 mesh), add 2% NaOH solution (solid-liquid ratio 1:12), heat to 65℃ at 1.5℃ / min, keep warm for 80min, and wash until neutral; Bamboo fiber modification: ultrasonic cleaning for 15 min, drying followed by plasma treatment (pressure 3000 Pa, power 200 W, time 8 min); coating with aminated molybdenum disulfide ethanol solution (concentration 0.8 wt%), and drying at 85 ℃ for 1.2 h; Preparation of bioactive polyolefins: PP resin was grafted with maleic anhydride via plasma (pressure 40 Pa, power 50 W, time 25 min, grafting rate 1.5%). Mixing and molding: Mix at a mass ratio of 25:74.2:0.8, calender into a film (70μm thickness) using a twin-screw extruder at 180℃ and 25 rpm, and heat-seal to make bags at 155℃ and 0.35MPa. Performance test results: tensile strength 46.3MPa, tear strength 31.2N / mm, puncture resistance 8.5N, antibacterial rate 99.92%, tensile strength retention rate after 51 cycles of use 81%, carbon footprint 0.45 tons CO2 / ton of product. Example 3 Bamboo fiber pretreatment: Take 120g of bamboo fiber powder (particle size 60 mesh), add a mixed alkaline solution of 3% NaOH containing 1% Na2SO3 (solid-liquid ratio 1:18), heat to 75℃ at 2.5℃ / min, keep warm for 100min, and wash until neutral; Bamboo fiber modification: ultrasonic cleaning for 25 min, drying followed by plasma treatment (pressure 8000 Pa, power 500 W, time 15 min); coating with aminated molybdenum disulfide ethanol solution (concentration 1.5 wt%), and drying at 95℃ for 1.8 h; Preparation of bioactive polyolefins: grafting maleic anhydride onto LLDPE resin (pressure 60 Pa, power 80 W, time 40 min, grafting rate 2.2%). Mixing and molding: Mix at a mass ratio of 40:58.5:1.5, extrude into a film (90μm thickness) using a twin-screw extruder at 200℃ and 35 rpm, and heat-seal to make bags at 170℃ and 0.45MPa. Performance test results: tensile strength 49.8MPa, tear strength 33.5N / mm, puncture resistance 9.8N, antibacterial rate 99.97%, tensile strength retention rate after 55 cycles 83%, carbon footprint 0.40 tons CO2 / ton of product. Example 4 Bamboo fiber pretreatment: Take 50g of bamboo fiber powder (particle size 100 mesh), add 1% NaOH solution (solid-liquid ratio 1:10), heat to 60℃ at 1℃ / min, keep warm for 60min, and wash until neutral; Bamboo fiber modification: ultrasonic cleaning for 15 min, drying followed by plasma treatment (pressure 1000 Pa, power 100 W, time 5 min); coating with aminated molybdenum disulfide ethanol solution (concentration 0.5 wt%), and drying at 80 ℃ for 1 h. Preparation of bioactive polyolefins: grafting maleic anhydride onto PP resin (pressure 10 Pa, power 20 W, time 10 min, grafting rate 1.2%). Mixing and molding: Mix at a mass ratio of 5:94.8:0.2, extrude in a twin-screw extruder at 170℃ and 15 rpm, cast into a film (thickness 60μm), and heat-seal into bags at 150℃ and 0.3MPa. Performance test results: tensile strength 45.2MPa, tear strength 30.1N / mm, puncture resistance 8.1N, antibacterial rate 99.90%, tensile strength retention rate after 50 cycles 80%, carbon footprint 0.48 tons CO2 / ton of product. Example 5 Bamboo fiber pretreatment: Take 150g of bamboo fiber powder (particle size 80 mesh), add 5% NaOH solution (solid-liquid ratio 1:20), heat to 80℃ at 3℃ / min, keep warm for 120min, and wash until neutral; Bamboo fiber modification: ultrasonic cleaning for 30 min, drying followed by plasma treatment (pressure 10000 Pa, power 800 W, time 30 min); ammoniated molybdenum disulfide ethanol solution (concentration 2 wt%) spray coating, and drying at 100℃ for 2 h. Preparation of bioactive polyolefins: grafting maleic anhydride onto LLDPE resin (pressure 100Pa, power 120W, time 100min, grafting rate 2.5%). Mixing and molding: Mix at a mass ratio of 30:65:5, calender into a film (100μm thickness) using a twin-screw extruder at 210℃ and 40 rpm, and heat-seal into bags at 180℃ and 0.5MPa. Performance test results: tensile strength 51.2MPa, tear strength 34.8N / mm, puncture resistance 10.3N, antibacterial rate 99.98%, tensile strength retention rate after 58 cycles 85%, carbon footprint 0.38 tons CO2 / ton of product.

[0021] In summary, the environmentally friendly bags prepared by this invention have excellent performance indicators: tensile strength ≥45MPa, tear strength ≥30N / mm, puncture resistance ≥8N, antibacterial rate against Escherichia coli and Staphylococcus aureus >99.9%, tensile strength retention rate after 50 cycles ≥80%, carbon footprint is reduced by more than 85% compared with traditional PE bags, and can be recycled and granulated for reuse after disposal, or naturally degraded in soil environment for 180-240 days.

[0022] 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 and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A bamboo fiber recyclable eco-friendly express delivery bag, characterized in that: It includes modified bamboo fiber, bioactive polyolefin, and aminated molybdenum disulfide, with the following mass percentages: bamboo fiber 5-40 wt%, bioactive polyolefin 60-95 wt%, and aminated molybdenum disulfide 0.1-5 wt%. The composite material is made into a film with a thickness of 60-100μm through melt co-extrusion process. The environmentally friendly bag has a tensile strength ≥45MPa, a tear strength ≥30N / mm, and an antibacterial rate of >99.9% against Escherichia coli and Staphylococcus aureus.

2. The bamboo fiber recyclable express delivery bag according to claim 1, characterized in that, The modified bamboo fiber is prepared by the following process: the bamboo fiber is heated to 60-80℃ at 1-3℃ / min and kept at that temperature for 60-120min in a 1-5% NaOH solution or a mixed alkaline solution containing 0.5-1.5% Na2SO3. After ultrasonic cleaning, it is treated with atmospheric pressure plasma at a gas pressure of 10-10000Pa and a discharge power of 10-800W for 0.5-30min, and then coated with an aminated two-dimensional molybdenum disulfide ethanol solution and dried.

3. The bamboo fiber recyclable express delivery bag according to claim 1, characterized in that, The aminated two-dimensional molybdenum disulfide was prepared by introducing amino (-NH2) and thiol (-SH) functional groups onto the surface of MoS2 via chemical grafting, with a grafting rate of 25-35%.

4. The bamboo fiber recyclable express delivery bag according to claim 1, characterized in that, The bioactive polyolefin was prepared by plasma-assisted grafting of maleic anhydride.

5. A method for preparing a bamboo fiber recyclable express delivery eco-friendly bag as described in any one of claims 1-4, characterized in that, Includes the following steps: (1) Bamboo fiber pretreatment: Add bamboo fiber to alkaline solution, heat and keep warm, and wash until neutral; (2) Bamboo fiber modification: After ultrasonic cleaning and atmospheric pressure plasma treatment, it is coated with aminated two-dimensional molybdenum disulfide ethanol solution and dried. (3) Preparation of bioactive polyolefins: maleic anhydride is grafted onto polyolefin resin via plasma; (4) Mixing and molding: Mix the components according to the ratio, melt-blend in a twin-screw extruder at 170-210℃, and heat-seal to make bags after forming a film.

6. The preparation method according to claim 5, characterized in that, In step (1), the alkaline solution is a NaOH solution with a mass fraction of 1-5% or a mixed alkaline solution containing 0.5-1.5% Na2SO3, with a solid-liquid ratio of 1:10-20, a heating rate of 1-3℃ / min, a holding temperature of 60-80℃, and a holding time of 60-120min.

7. The preparation method according to claim 5, characterized in that, In step (2), the ultrasonic cleaning parameters are 40kHz frequency, 300W power, and cleaning time of 15-30min; the atmospheric pressure plasma treatment has a gas pressure of 10-10000Pa, a discharge power of 10-800W, and a treatment time of 0.5-30min; the concentration of the aminated two-dimensional molybdenum disulfide ethanol solution is 0.5-2wt%, the drying temperature after coating is 80-100℃, and the drying time is 1-2h.

8. The preparation method according to claim 5, characterized in that, In step (3), the polyolefin resin is linear low-density polyethylene (LLDPE) or polypropylene (PP); the gas pressure for plasma-assisted grafting of maleic anhydride is 1-100 Pa, the discharge power is 4-120 W, the treatment time is 0.1-100 min, and the maleic anhydride grafting rate is 1.2-2.5%.

9. The preparation method according to claim 5, characterized in that, In step (4), the melt blending temperature of the twin-screw extruder is 170-210℃, the main machine speed is 10-40 rpm, the film forming method is extrusion, casting or calendering, the film thickness is 60-100μm, the heat sealing bag making temperature is 150-180℃, and the heat sealing pressure is 0.3-0.5MPa.

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