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The microbial barrier performance of thermoforming packaging film depends first on its material composition. Traditional packaging materials, such as polyethylene (PE) and polypropylene (PP), have certain physical and chemical stability, but they perform mediocrely in terms of microbial barrier. In order to enhance the microbial barrier performance, the industry has begun to explore new materials with antibacterial properties.
Application of nanosilver and chitosan: Nanosilver has become an ideal antibacterial additive in thermoforming packaging film due to its broad-spectrum antibacterial properties and low resistance to drug resistance. By evenly dispersing nanosilver particles in the film material, the growth of microorganisms such as bacteria and mold can be effectively inhibited. Chitosan is a natural high molecular weight polysaccharide with good biocompatibility and antibacterial properties. Chitosan film can not only effectively block microorganisms, but also promote wound healing, so it has broad application prospects in the field of medical packaging.
Addition of antimicrobial agents: In addition to nanosilver and chitosan, other antimicrobial agents such as quaternary ammonium salts and organic acids are also widely used in thermoforming packaging films. These antimicrobial agents inhibit the growth of microorganisms by destroying the cell walls of microorganisms or interfering with their metabolic processes.
Structural design is another key aspect to improve the microbial barrier properties of thermoformed packaging films. Multilayer coextrusion technology forms a composite film with a multi-layer structure by coextruding film layers of different materials and functions. This structure not only improves the physical strength, chemical stability and barrier properties of the film, but also provides more possibilities for microbial barrier.
Setting of barrier layer: In multilayer coextruded films, one or more barrier layers are usually set to block the penetration of oxygen, water vapor and microorganisms. These barrier layers may be made of high barrier materials such as EVOH (ethylene-vinyl alcohol copolymer) and PA (nylon) to ensure that the film has excellent microbial barrier properties.
Addition of functional layer: In addition to the barrier layer, multilayer coextruded films can also add other functional layers as needed, such as antibacterial layer, moisture-proof layer, UV-resistant layer, etc. The addition of these functional layers further enhances the microbial barrier properties of the film, enabling it to cope with more diverse packaging needs.
The production process also has an important influence on the microbial barrier properties of thermoformed packaging films. During the production process of the film, parameters such as raw material quality, processing temperature, and extrusion speed need to be strictly controlled to ensure the uniformity and stability of the film. In addition, the film needs to be strictly inspected and tested to ensure that its microbial barrier properties meet the relevant standards and requirements.
Raw material quality control: The quality of the raw materials directly affects the microbial barrier properties of the film. Therefore, the raw materials need to be strictly screened during the production process to ensure that their purity, stability, and antibacterial properties meet the requirements.
Processing temperature and extrusion speed: Processing temperature and extrusion speed are key factors affecting the structure and performance of the film. Too high processing temperature may cause the raw materials to decompose, produce odors and harmful substances; while too low processing temperature may cause uneven film structure and decreased performance. Similarly, too fast or too slow extrusion speed will also affect the uniformity and stability of the film. Therefore, these parameters need to be strictly controlled during the production process to ensure the microbial barrier properties of the film.
In addition to material composition, structural design, and production process, the sealing, thickness, and surface treatment of the film are also important factors affecting its microbial barrier properties.
Sealing: Good sealing is the key to ensuring the sterility of the internal environment of the package. Thermoformed packaging films are usually sealed by heat sealing or ultrasonic sealing. In order to ensure the sealing effect, parameters such as sealing temperature, pressure and time need to be strictly controlled to avoid problems such as leaking and virtual sealing.
Thickness: The thickness of the film directly affects its barrier properties and mechanical strength. Generally speaking, thicker films have better barrier properties and mechanical strength, but they also increase cost and weight. Therefore, when choosing the thickness of the film, it is necessary to comprehensively consider factors such as product packaging needs, cost and transportation.
Surface treatment: Surface treatment can improve the surface tension, wettability and adhesion of the film, thereby enhancing its fit and sealing effect with the packaged object. Common surface treatment methods include corona treatment, plasma treatment, flame treatment, etc. These treatment methods can not only improve the microbial barrier properties of the film, but also improve its printing and lamination properties.
