Multilayer coextruded films are much sought after in the food packaging sector due to their excellent protective qualities. With the use of these films, which combine the qualities of several materials, food can be kept fresh and tasty while also having its shelf life extended. The main elements of these films, interlayer adhesives, will be discussed in this paper together with how they improve the overall performance of the film.

Regarding food packing, adhesives in multilayer coextruded films cannot be replaced

Because multilayer coextruded films can offer chemical, microbiological, and physical barriers among other kinds, they are the material of choice in the food packaging industry. Frequently made of several layers of polymer, each layer has a particular function, like barrier qualities, mechanical strength, or heat sealing. The intricacy of them defines them. But compatibility problems usually restrict the combinations that can be formed between several polymers. Here is when interlayer adhesives start to be required.

Adhesives’ Functions

Tie layers are a unique family of compounds also referred to as adhesives. The capacity of these materials to create chemical or physical connections enhances the adhesion between several polymer layers. If the film will hold together throughout processing and usage depends on this adherence.

The Many Adhesive Types and Typical Examples of Each

Reactive and non-reactive adhesives can be distinguished one from the other by their chemical makeup and intended use. Reactive adhesives can be used to form covalent connections between polymer layers, therefore strengthening the adhesion between them. Conversely, physical adsorption or diffusion is how non-reactive adhesives become sticky.

Many times, adhesives are employed in multilayer coextruded films

Apart from improving the film’s structural integrity, adhesives in food packaging also help to accomplish specific functions. One can combine polyamide (PA) and polyethylene (PE) to produce a polymer with outstanding properties for both water vapor and oxygen barriers. Perishable products need this to keep them on the shelf longer.

Relevance of Specifications to Adhesive Performance

The chemical make-up, processing settings, and interactions an adhesive has with other polymer layers are just a few of the elements that affect its performance. You can enhance contact with the polymer layer and encourage adhesion, for instance, by raising the processing temperature. An adhesive, however, may deteriorate and become less effective at excessively high temperatures.

Developing Multi-Layer Coextruded Films

Many times, coextrusion—the simultaneous extrusion of two or more polymers and their fusing into a single material—is used to produce multilayer coextruded films. The ultimate application of the film will decide which kind of molding—blow molding or casting—will be used.

Improvement of several adhesives

The best potential bonding result depends on the glue being correctly formulated. This is so because the adhesive has to be flexible, clear, and adhesion balanced. Furthermore, because it immediately affects the contact area and the binding strength between the adhesive and the polymer layer, the adhesive thickness is a crucial element.

The adhesive function of COACE

Developing high-performance materials for food packaging mostly depends on the adhesive of multilayer coextruded films. Films with the necessary mechanical strength and exceptional barrier properties can be produced by choosing the right kind of adhesive and refining the formulation and production conditions. Innovation in the food packaging industry will mostly come from the advancement of adhesive technology as long as the industry values sustainability and functionality.

The role of adhesives in high barrier films

EVOH has excellent barrier properties to gases and oils, achieving high barrier effects against oxygen, water, carbon dioxide, odors, etc.

Due to the poor affinity between some base resins and functional layer resins, some adhesive layers need to be placed between the two layers to act as glue in order to form an “integrated” composite film.
The main material of K2B of Coase contains vinyl acetate monomer in the molecular chain, which reduces the crystallinity of polyethylene and further improves the heat sealing performance of the composite film.

The role of compatibilizers in medium barrier films

Coase’s W1L is polyethylene grafted with MAH as the base material, and polar group side groups are introduced on the non-polar chain. It is an adhesive for polar materials and non-polar materials.
W1L can play a connecting role in the composite film of polypropylene, polyolefin and nylon. MAH reacts with the amino group of nylon, greatly improving the bonding strength between the base resin and the functional layer resin.

Contacting the knowledgeable personnel at COACE Chemical Polymer is advised for those of you interested in adhesives for multilayer coextruded films or any of our other plastic modifiers and other products. Our professionals will help and advise you.