Environment-friendly degradable food packaging material and preparation method thereof

Abstract

The invention discloses an environment-friendly degradable food packaging material and a preparation method thereof, and relates to the technical field of packaging materials, the material comprises the following components by weight: 55%-65% of polylactic acid; 25% to 30% of modified starch; 5% to 10% of pretreated natural plant fibers; 1% to 3% of a biodegradation accelerator comprising a specific enzyme; a novel bio-based plasticizer derived from vegetable oil: 1% to 5%; nano silver particles: 0.01% to 0.5%; a natural antioxidant; nano-scale titanium dioxide; according to the technical scheme, the antibacterial packaging material can be decomposed in the natural environment and cannot pollute the environment, then nano-silver particles are added into the material, the packaging material is endowed with the excellent antibacterial performance, meanwhile, due to introduction of nanoscale titanium dioxide, the photocatalytic performance of the material is enhanced, and the photocatalytic performance of the packaging material is improved. The antibacterial effect can be improved, and the food safety is further guaranteed.

Description

Technical Field

[0001] This invention relates to the field of packaging materials technology, and in particular to an environmentally friendly and biodegradable food packaging material and its preparation method. Background Technology

[0002] With increasing global awareness of environmental protection, the environmental pollution caused by traditional plastic products due to their difficulty in degradation is becoming increasingly serious. Particularly in the food packaging sector, single-use plastic packaging materials, due to their large usage and difficulty in post-disposal, have become one of the main sources of environmental pollution. Therefore, developing environmentally friendly and biodegradable food packaging materials has become a key research focus.

[0003] Currently available biodegradable materials on the market mainly include polylactic acid (PLA) and modified starch. While these materials possess a certain degree of biodegradability, they have shortcomings in mechanical properties and water resistance, limiting their widespread application. Furthermore, existing biodegradable materials often lack sufficient antibacterial properties, which is a significant consideration in the food packaging industry, as antibacterial performance directly impacts food safety and freshness.

[0004] In recent years, the development of nanotechnology has provided new avenues for improving existing biodegradable materials. Nanomaterials such as silver nanoparticles and nanoscale titanium dioxide, due to their unique physical and chemical properties, such as excellent antibacterial properties and photocatalytic activity, have shown great potential in improving material performance. However, how to effectively and uniformly disperse these nanomaterials in a matrix material to fully realize their performance advantages remains a technical challenge. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide an environmentally friendly biodegradable food packaging material and its preparation method, so as to solve the problem that existing biodegradable materials often lack sufficient antibacterial properties.

[0006] In view of this, the present invention provides an environmentally friendly and biodegradable food packaging material and a method for preparing the same, the material comprising the following components by weight percentage:

[0007] Polylactic acid: 55% to 65%;

[0008] Modified starch: 25% to 30%;

[0009] Pretreated natural plant fibers: 5% to 10%;

[0010] Biodegradation promoters containing specific enzymes: 1% to 3%;

[0011] A novel bio-based plasticizer derived from vegetable oil: 1% to 5%;

[0012] Silver nanoparticles: 0.01% to 0.5%;

[0013] Natural antioxidants: 0.1% to 2%;

[0014] Nanoscale titanium dioxide: 0.05% to 0.5%;

[0015] The nano-silver particles and nano-sized titanium dioxide provided excellent antibacterial and photocatalytic properties, while the natural antioxidants helped to slow down the oxidation process of food, thereby improving food safety and extending its shelf life.

[0016] Optionally, the natural plant fiber is bamboo fiber or wood fiber that has undergone nano-sizing treatment. The nano-sizing treatment includes using chemical or physical methods to reduce the fiber size to the nanoscale to improve its compatibility with the PLA matrix and enhance the mechanical properties of the composite material.

[0017] Optionally, the modified starch is cross-linked corn starch, and the cross-linking treatment is carried out using a chemical cross-linking agent to improve the water resistance and heat-sealing performance of the material.

[0018] This invention also protects a method for preparing an environmentally friendly and biodegradable food packaging material, comprising the following steps:

[0019] PLA is blended with modified starch and then melt-extruded. Pretreated natural plant fibers, biodegradation promoters, bio-based plasticizers, nano-silver particles, natural antioxidants and nano-sized titanium dioxide are then added and mixed under set conditions. The mixture is then formed into a film by a twin-screw extruder.

[0020] The setting conditions include:

[0021] The temperature should be controlled between 180 and 200 degrees Celsius;

[0022] The stirring speed is 500-1000 rpm;

[0023] The mixing time is 5-15 minutes;

[0024] Ultrasonic dispersion technology was used in the mixing stage at a frequency of 20 kHz for a duration of 30 seconds.

[0025] Optionally, a liquid coating containing antioxidants and moisture-proofing agents is added during the melt extrusion process to improve the stability and moisture-proofing effect of the final product and prevent food from oxidizing and deteriorating.

[0026] Optionally, after the film is formed, it is microwaved for 1-5 minutes at a power of 600W to promote cross-linking of the internal structure, thereby enhancing the mechanical strength and tear resistance of the material.

[0027] Optionally, the process may also include a step of coating the surface of the film with an antimicrobial layer made of natural oils (such as beeswax) to prevent microbial growth and extend the shelf life of the food.

[0028] Optionally, ultrasonic dispersion technology is used in the mixing stage at a frequency of 20 kHz for a duration of 30 seconds to ensure that the nano-silver particles and nano-sized titanium dioxide are uniformly distributed in the material, thereby achieving more effective antibacterial and photocatalytic properties.

[0029] Optionally, before film forming, the mixed material is placed in a vacuum environment for degassing for 10-20 minutes to remove air bubbles and improve the transparency and smoothness of the film.

[0030] Optionally, the silver nanoparticles are added to the mixture by solution blending and dispersed by ultrasonic pretreatment before mixing to ensure uniform distribution of the silver nanoparticles.

[0031] As can be seen from the above technical solutions, the embodiments of the present invention have the following advantages:

[0032] 1. The present invention discloses an environmentally friendly and biodegradable food packaging material and its preparation method. The material is composed of bio-based materials such as polylactic acid and modified starch, which can decompose in the natural environment without causing pollution and meet the requirements of green environmental protection. By adding nano-silver particles to the material, the present invention endows the packaging material with excellent antibacterial properties, which helps to prevent the growth of microorganisms and extend the shelf life of food. At the same time, the introduction of nano-sized titanium dioxide not only enhances the photocatalytic performance of the material, but also helps to improve its antibacterial effect, further ensuring food safety.

[0033] 2. The present invention provides an environmentally friendly and biodegradable food packaging material and its preparation method. By selecting a specific proportion of PLA, modified starch, and nano-processed natural plant fibers, the present invention improves the mechanical strength and toughness of the material, making it more suitable for food packaging. At the same time, the use of natural antioxidants helps to delay the food oxidation process, thereby improving food safety and extending the shelf life of food.

[0034] These features and advantages of the present invention will be disclosed in detail in the following specific embodiments and accompanying drawings. Attached Figure Description

[0035] The invention will be further described below with reference to the accompanying drawings:

[0036] Figure 1 This is a flowchart illustrating the preparation method of an environmentally friendly and biodegradable food packaging material according to the present invention. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be explained and described below with reference to the accompanying drawings. However, the following embodiments are only preferred embodiments of the present invention and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments in the implementation methods without creative effort are all within the protection scope of the present invention.

[0038] The following describes in detail, with reference to the accompanying drawings, an environmentally friendly and biodegradable food packaging material and its preparation method according to an embodiment of the present invention.

[0039] Example 1

[0040] For easier understanding, please refer to Figure 1 This invention provides an embodiment of an environmentally friendly and biodegradable food packaging material and its preparation method. The main components of the environmentally friendly and biodegradable food packaging material are:

[0041] Polylactic acid (PLA): 55%-65%

[0042] Modified starch: 25%-30%, preferably cross-linked corn starch.

[0043] Pretreated natural plant fibers: 5%-10%, preferably nano-sized bamboo or wood fibers.

[0044] Biodegradation promoters containing specific enzymes: 1%-3%

[0045] Novel bio-based plasticizers derived from vegetable oils: 1%-5%

[0046] Silver nanoparticles: 0.01%-0.5%

[0047] Natural antioxidants (such as rosemary extract): 0.1%-2%

[0048] Nanoscale titanium dioxide (TiO2): 0.05%-0.5%

[0049] The preparation steps are as follows:

[0050] Premixing: First, weigh PLA and modified starch according to the ratio and put them into a high-speed mixer for preliminary mixing.

[0051] Melt extrusion: The above premixed material is fed into a twin-screw extruder and melt extruded at a temperature of 180-200℃.

[0052] Other components added: During the melt extrusion process, pretreated natural plant fibers, biodegradation promoters, bio-based plasticizers, nano silver particles, natural antioxidants, and nano-sized titanium dioxide are added sequentially.

[0053] Mixing and dispersing: Keep the extruder stirring speed between 500-1000 rpm and the mixing time between 5-15 minutes. During this period, apply ultrasonic dispersion technology (frequency 20 kHz, duration 30 seconds) to ensure uniform distribution of nanoparticles.

[0054] Adding a liquid coating: During the extrusion process, a liquid coating containing antioxidants (such as vitamin E) and moisture-proofing agents (such as silicone) is sprayed simultaneously to improve the stability and moisture-proof effect of the film.

[0055] Film forming: The mixed materials are formed into a film through a twin-screw extruder.

[0056] Microwave treatment: The molded film is microwave treated (time 1-5 minutes, power 600W) to promote cross-linking of the internal structure of the material and improve mechanical strength.

[0057] Surface coating: A layer of antibacterial material, such as beeswax, is coated onto the surface of the film to further prevent the growth of microorganisms.

[0058] Degassing treatment: Before film forming, the mixed materials are degassed in a vacuum environment (for 10-20 minutes) to remove air bubbles and improve the transparency and smoothness of the film.

[0059] Dispersion of silver nanoparticles: Silver nanoparticles are added by solution blending and pre-dispersed by ultrasonic treatment before mixing to ensure their uniform distribution in the material.

[0060] In summary, the environmentally friendly and biodegradable food packaging material prepared in this embodiment has good antibacterial properties, photocatalytic properties, antioxidant properties, and excellent mechanical properties, making it suitable for various food packaging needs.

[0061] Example 2

[0062] To enhance the antibacterial properties of the material, this embodiment adjusts the proportion of nano-silver particles to the upper limit and increases the content of nano-sized titanium dioxide to strengthen the photocatalytic effect. The specific formulation is as follows:

[0063] Polylactic acid (PLA): 60%

[0064] Modified starch: 27%

[0065] Pretreated natural plant fibers (nano-treated bamboo fiber): 8%

[0066] Biodegradation promoters containing specific enzymes: 2%

[0067] Novel bio-based plasticizers derived from vegetable oils: 3%

[0068] Silver nanoparticles: 0.5%

[0069] Natural antioxidants (such as rosemary extract): 1%

[0070] Nanoscale titanium dioxide (TiO2): 0.5%

[0071] Preparation steps

[0072] Premixing: PLA and modified starch are premixed in a high-speed mixer.

[0073] Melt extrusion: In a twin-screw extruder, the premix is ​​heated to 190°C and melt extruded.

[0074] Other components added: During the extrusion process, nano-treated bamboo fiber, biodegradation promoter, bio-based plasticizer, nano silver particles, natural antioxidant and nano-sized titanium dioxide are added in sequence.

[0075] Mixing and dispersing: Maintain a stirring speed of 800 rpm for 10 minutes and apply ultrasonic dispersion technology (frequency 20 kHz, duration 30 seconds) to ensure uniform dispersion of nano-silver particles and nano-sized titanium dioxide.

[0076] Add liquid coating: Spray a liquid coating containing antioxidants (such as vitamin E) and moisture-proofing agents (such as silicone) during the extrusion process.

[0077] Film forming: The mixed materials are formed into a film through a twin-screw extruder.

[0078] Microwave treatment: The formed film is subjected to microwave treatment (3 minutes, 600W).

[0079] Surface coating: A layer of antibacterial material composed of natural oils (such as beeswax) is coated onto the surface of the film.

[0080] Degassing treatment: Before film forming, the mixed materials are degassed in a vacuum environment (time 15 minutes).

[0081] Dispersion of silver nanoparticles: Silver nanoparticles are added by solution blending and dispersed by ultrasonic pretreatment before mixing.

[0082] Performance evaluation

[0083] The environmentally friendly biodegradable food packaging material prepared in this embodiment has excellent antibacterial and photocatalytic properties, making it suitable for food packaging that requires long-term preservation and has high antibacterial requirements.

[0084] Example 3

[0085] To improve the transparency of the material, this embodiment reduces the content of nano-silver particles and nano-sized titanium dioxide, and optimizes the proportion of natural antioxidants. The specific formulation is as follows:

[0086] Polylactic acid (PLA): 65%

[0087] Modified starch: 25%

[0088] Pretreated natural plant fibers (nano-treated wood fibers): 5%

[0089] Biodegradation promoters containing specific enzymes: 1%

[0090] Novel bio-based plasticizers derived from vegetable oils: 4%

[0091] Silver nanoparticles: 0.01%

[0092] Natural antioxidants (such as rosemary extract): 0.1%

[0093] Nanoscale titanium dioxide (TiO2): 0.05%

[0094] Preparation steps

[0095] Premixing: PLA and modified starch are premixed in a high-speed mixer.

[0096] Melt extrusion: In a twin-screw extruder, the premix is ​​heated to 185°C and melt extruded.

[0097] Other components added: During the extrusion process, nano-treated wood fibers, biodegradation promoters, bio-based plasticizers, nano-silver particles, natural antioxidants, and nano-sized titanium dioxide are added sequentially.

[0098] Mixing and dispersing: Maintain a stirring speed of 700 rpm for 12 minutes and apply ultrasonic dispersion technology (frequency 20 kHz, duration 30 seconds) to ensure uniform dispersion of nano-silver particles and nano-sized titanium dioxide.

[0099] Add liquid coating: Spray a liquid coating containing antioxidants (such as vitamin E) and moisture-proofing agents (such as silicone) during the extrusion process.

[0100] Film forming: The mixed materials are formed into a film through a twin-screw extruder.

[0101] Microwave treatment: The formed film is subjected to microwave treatment (time 2 minutes, power 600W).

[0102] Surface coating: A layer of antibacterial material composed of natural oils (such as beeswax) is coated onto the surface of the film.

[0103] Degassing treatment: Before film forming, the mixed materials are degassed in a vacuum environment (time 20 minutes).

[0104] Dispersion of silver nanoparticles: Silver nanoparticles are added by solution blending and dispersed by ultrasonic pretreatment before mixing.

[0105] In summary, the environmentally friendly and biodegradable food packaging material prepared in this embodiment has high transparency and smoothness, making it suitable for food packaging with strong display requirements, while still retaining basic antibacterial and photocatalytic functions.

[0106] Ultrasonic dispersion technology utilizes high-frequency vibration waves to disrupt the aggregation forces between particles, thereby achieving uniform dispersion of particles in a liquid or solid matrix. In this invention, ultrasonic dispersion technology is primarily used to ensure the uniform distribution of nano-silver particles and nano-sized titanium dioxide in environmentally friendly, biodegradable food packaging materials. The specific working principle and technical characteristics of ultrasonic dispersion technology are as follows:

[0107] Working Principle: An ultrasonic generator produces high-frequency sound waves (typically around 20kHz), which are converted into mechanical vibration energy by a transducer. When the ultrasonic waves pass through a liquid medium, they form tiny bubbles within the liquid. As the pressure of the sound waves changes periodically, these bubbles rapidly expand and collapse after reaching a certain size—a process called cavitation. The localized high temperature and pressure generated by cavitation produce strong shear forces and shock waves, which can disrupt the cohesive forces between particles, causing them to disperse. Due to the strong stirring effect caused by cavitation, nanoscale particles can be effectively separated from their agglomerate state and uniformly distributed throughout the mixture, thus preventing agglomeration.

[0108] Technical Features: Ultrasonic dispersion technology can effectively disperse nanoparticles in a shorter time, improving production efficiency. Compared to traditional mechanical stirring methods, ultrasound can penetrate deeper into the mixture, ensuring uniform distribution of nanoparticles within the material. Ultrasonic dispersion technology is suitable not only for dispersion in liquid systems but also for dispersion of nanoparticles in solid mixtures. By adjusting parameters such as the power, frequency, and duration of the ultrasound, the dispersion effect can be precisely controlled to adapt to different production process requirements.

[0109] In the preparation process of this invention, the application of ultrasonic dispersion technology is mainly in the mixing stage, and the specific steps are as follows:

[0110] Prepare the mixture: First, mix PLA, modified starch and other ingredients evenly according to the formula ratio.

[0111] Introducing nanomaterials: Nano-silver particles and nano-sized titanium dioxide were added to the above mixture.

[0112] Ultrasonic treatment: Turn on the ultrasonic generator, set the frequency to 20kHz, and the duration to 30 seconds. At this time, the ultrasonic waves will generate a cavitation effect in the mixture, promoting the uniform dispersion of nanoparticles.

[0113] Subsequent processing: After ultrasonic dispersion, other preparation steps are carried out, such as melt extrusion and film forming.

[0114] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. An environmentally friendly and biodegradable food packaging material, characterized in that: The material consists of the following components by weight percentage. composition: Polylactic acid: 55% to 65%; Modified starch: 25% to 30%; Pretreated natural plant fibers: 5% to 10%; Biodegradation promoters containing specific enzymes: 1% to 3%; A novel bio-based plasticizer derived from vegetable oil: 1% to 5%; Silver nanoparticles: 0.01% to 0.5%; Natural antioxidants: 0.1% to 2%; Nanoscale titanium dioxide: 0.05% to 0.5%; The silver nanoparticles and nano-sized titanium dioxide described therein provide excellent antibacterial and photocatalytic properties, while the natural antioxidants help to slow down the oxidation process of food.

2. The environmentally friendly and biodegradable food packaging material according to claim 1, characterized in that: The natural plant fiber is bamboo fiber or wood fiber that has undergone nano-sizing treatment. The nano-sizing treatment includes using chemical or physical methods to reduce the fiber size to the nanoscale to improve its compatibility with the PLA matrix.

3. The environmentally friendly and biodegradable food packaging material according to claim 1, characterized in that: The modified starch is cross-linked corn starch, and the cross-linking treatment is carried out using a chemical cross-linking agent to improve the material's water resistance and heat-sealing performance.

4. A method for preparing an environmentally friendly biodegradable food packaging material according to any one of claims 1-3, characterized in that: Includes the following steps: PLA is blended with modified starch and then melt-extruded. Pretreated natural plant fibers, biodegradation promoters, bio-based plasticizers, nano-silver particles, natural antioxidants and nano-sized titanium dioxide are then added and mixed under set conditions. The mixture is then formed into a film by a twin-screw extruder. The setting conditions include: The temperature should be controlled between 180 and 200 degrees Celsius; The stirring speed is 500-1000 rpm; The mixing time is 5-15 minutes; Ultrasonic dispersion technology was used in the mixing stage at a frequency of 20 kHz for a duration of 30 seconds.

5. The method for preparing an environmentally friendly and biodegradable food packaging material according to claim 4, characterized in that: A liquid coating containing antioxidants and moisture-proofing agents was added during the melt extrusion process.

6. The method for preparing an environmentally friendly biodegradable food packaging material according to claim 4, characterized in that: After the film is formed, it is microwaved for 1-5 minutes at a power of 600W to promote cross-linking of the internal structure.

7. The method for preparing an environmentally friendly and biodegradable food packaging material according to claim 4, characterized in that: It also includes a step of coating the film surface with an antimicrobial layer made of natural oils to prevent microbial growth and extend the shelf life of the food.

8. The method for preparing an environmentally friendly and biodegradable food packaging material according to claim 4, characterized in that: Ultrasonic dispersion technology was used in the mixing stage at a frequency of 20 kHz for a duration of 30 seconds to ensure that the nano-silver particles and nano-sized titanium dioxide were uniformly distributed in the material.

9. The method for preparing an environmentally friendly and biodegradable food packaging material according to claim 4, characterized in that: Before film forming, the mixed material is placed in a vacuum environment for degassing for 10-20 minutes to remove air bubbles from the material.

10. The method for preparing an environmentally friendly biodegradable food packaging material according to claim 4, characterized in that: The silver nanoparticles are added to the mixture by solution blending and dispersed by ultrasonic pretreatment before mixing.

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