Coextruded films with many layers are extremely important in a variety of industries, particularly in the packaging industry, where they are used for applications that require outstanding barrier qualities. By providing protection against oxygen, moisture, light, and other environmental factors that have the potential to impair the quality of packed items and shorten their shelf life, these films are designed to be implemented. The purpose of this article is to investigate various strategies and methods that can be utilized to enhance the barrier properties of multi-layer coextruded films. Through the examination of a variety of perspectives, such as the selection of materials, the arrangement of layers, the modification of surfaces, and the technologies used for coating, we are able to acquire insights into successful strategies for improving the barrier performance of these films.
The selection of materials
a. Barrier Polymers: When it comes to increasing the barrier properties of coextruded films, selecting the suitable barrier polymers is something that is absolutely essential. For the purpose of improving barrier performance, it is possible to integrate polymers that have intrinsically high barrier qualities into the structure of the film. Some examples of such polymers include ethylene vinyl alcohol (EVOH), polyamide (PA), and polyvinylidene chloride (PUDC).
b. Nanocomposites: The incorporation of nanoscale fillers or additives into the polymer matrix, such as clay nanoparticles or graphene oxide, has the potential to considerably improve the barrier properties of coextruded films. These nanocomposites produce winding pathways for the diffusion of gases and moisture, which effectively reduces the permeability of the material.
c. The total barrier performance of coextruded films can be improved by using hybrid structures, which involve the utilization of a combination of various polymers that have barrier qualities that are complementary to one another. It is possible to create hybrid structures by utilizing barrier layers in conjunction with other functional layers or by adding various barrier polymers into the structure.
Layer Arrangement
a. Positioning of the Barrier Layer: Bringing the barrier layer closer to the surface that is exposed to the external environment might help improve the overall barrier properties of films that have been coextruded. Because of this location, the diffusion channel for gases and moisture is reduced, which results in an improvement in the barrier performance of the film.
Interlayer Adhesion: It is essential to ensure that there is a strong interlayer adhesion between the various polymer layers in order to prevent the production of microcracks or delamination, both of which might affect the barrier qualities of the material. During the coextrusion process, it is possible to achieve good interlayer bonding by controlling the processing conditions, such as temperature and pressure, in the appropriate manner.
c. Core Layer Design: By optimizing the properties of the core layer, which is surrounded by barrier layers, it is possible to contribute to improved barrier performance. The coextruded film may benefit from the core layer’s capacity to provide mechanical strength, dimensional stability, or extra barrier qualities.
Surface Modification
a. The surface properties of coextruded films can be effectively modified by the use of plasma treatment, which is one of the methods that is included in surface modification. Increasing surface energy, improving wettability, and enhancing the adherence of coatings or barrier layers are all possible outcomes of this substance. The film’s cleanliness can also be improved through the use of plasma treatment, which can eliminate impurities.
b. Coating Technologies: The application of barrier coatings, such as silicon oxide (SiOx), aluminum oxide (AlOx), or plasma-enhanced chemical vapor deposition (PECVD) coatings, has the potential to considerably improve the barrier properties of coextruded films. These coatings offer an additional barrier layer that is highly resistant to both substances that include gas and moisture.
c. By modifying the surface topography of coextruded films, such as by producing micro- or nanostructures, it is possible to lower the contact area between the film and the substances that are penetrating, which in turn improves the barrier performance of the film. Approaches like laser patterning and embossing are two examples of techniques that can be utilized for surface texturing.
In addition to its dedication to research and development, manufacture, and service of multi-layer co-extruded film additives, COACES possesses a research and development team that is directed by a number of senior engineers and doctors. COACES multi-layer extruded film additives are selected by the majority of users because they possess the qualities of high transparency, low crystal point, high grafting rate, and good fluidity. These properties distinguish them from other additives. This has the potential to significantly enhance the barrier qualities of multi-layer co-extruded films, as well as improve the efficiency with which they are applied!
Quality Assurance and Testing Methods
a. Control of Thickness: It is vital to ensure that the layer thickness of the coextruded film is consistent throughout the whole coating in order to maintain homogeneous barrier qualities. Controlling the extrusion parameters with great precision, such as the melt temperature, die spacing, and line speed, is absolutely necessary in order to obtain the correct film thickness.
a. Testing for Permeability: Conducting regular tests to determine the permeability properties of the coextruded films, such as the oxygen transmission rate (OTR), the moisture vapor transmission rate (MVTR), or the light transmission properties, gives valuable data that can be used to evaluate the success of barrier enhancements. By doing so, it is possible to make any necessary alterations to the structure or content of the film.
It is possible to evaluate the long-term barrier performance of coextruded films by conducting shelf life tests, which can be either accelerated shelf life studies or real-time shelf life testing. The film of barrier polymers, nanocomposites, and hybrid structures, together with optimal layer placement and interlayer adhesion, contributes to better barrier qualities. These investigations imitate the actual storage circumstances and assist evaluate the quality of the film. Additional enhancements to the film’s resistance to gases, moisture, and other external variables can be achieved through the application of surface modification techniques, such as plasma treatment or coating technology. Controlling the thickness of the barrier, conducting permeability tests, and conducting shelf life studies are all examples of quality control techniques that assure consistent and reliable barrier performance. Manufacturers are able to make multi-layer coextruded films with superior barrier qualities by following these tactics. This allows them to address the growing demand for high-quality packaging solutions across a variety of industries.
