The multilayer coextruded films have brought about a revolution in the packaging sector by providing a versatile solution that can cater to the varied requirements of a wide range of products. The films in question are made up of numerous layers of distinct polymers, each of which contributes a unique set of characteristics, including protection against barriers, strength, and flexibilities. Nevertheless, the seamless integration of these layers presents a barrier in the absence of the use of polymer adhesives that are effective. In this article, we investigate the significant function that polymer adhesives play in multilayer coextruded films, with a particular emphasis on the manner in which these adhesives handle the deficiencies and difficulties that are inherent in multilayer packaging materials.

The Understanding of Coextruded Films with Multiple Layers

The purpose of multilayer coextruded films is to create a single high-performance packaging material that combines the advantageous features of a number of distinct polymers. Each layer performs a distinct function, such as boosting mechanical strength and flexibility, providing barrier protection against oxygen, moisture, light, and other factors, and giving protection against other elements. It is not sufficient to merely stack these layers together in order to guarantee that they will function as a coherent film and that they will be cohesive. The importance of polymer adhesives cannot be overstated in this context.

Guaranteeing the Cohesion and Integrity of the Layers

In multilayer coextruded films, one of the key responsibilities of polymer adhesives is to ensure that the different layers adhere to one another in a robust manner. If the layers do not adhere to one another effectively, they may delaminate or separate, which would compromise the barrier qualities of the film as well as its structural integrity. Creating a coherent film structure is accomplished by the use of polymer adhesives, which serve as the bonding agent that holds the layers together.

The selection of a polymer adhesive is of utmost importance since it must provide compatibility with the numerous polymers that are utilised in the film while also delivering exceptional adhesion strength. In order to accomplish this goal, adhesives such as ethylene acrylic acid copolymers (EAA), adhesives based on polyethylene, or tie resins are frequently utilised. These adhesives have the capability of bonding various polymer surfaces, so producing a robust interface between the layers inside the structure.

Improving the Performance of the Barrier

Polymer adhesives, in addition to ensuring that layers adhere to one another, contribute to the overall barrier performance of those films that are coextruded with several layers. When adhesives are properly designed, they have the ability to fill in gaps and voids between layers, so lowering the likelihood that oxygen, moisture, or other pollutants would penetrate in between the layers.

For instance, polymer adhesives are useful in the packaging of food, where it is essential to preserve the product’s freshness and shelf life. These adhesives help to establish a continuous barrier that prevents oxygen from entering the product. When it comes to products that are sensitive to deterioration as a result of exposure to oxygen, such as meat, cheese, and snacks, this is of utmost importance. Through the process of blocking potential pathways for oxygen transmission, the adhesive improves the barrier qualities of the film, which in turn reduces the amount of time the product can be stored.

Enhancing the Mechanical Strength and Durability of the Product

Additionally, polymer adhesives have a vital role in the enhancement of the mechanical strength and endurance of multilayer coextruded films to a large degree. Throughout the preparation, handling, transit, and storage processes, these films are subjected to a variety of stressed conditions. It is possible that the film will break under these conditions if there is insufficient adhesion between the layers, which could result in splits, punctures, or leaks.

The inclusion of polymer adhesives helps to distribute stress more uniformly across the film, which in turn improves the film’s resistance to tearing and puncturing. The capacity of the film to stretch without tearing is facilitated by adhesives that possess high elongation and toughness capabilities. One example of such adhesives is those that are based on polyethylene. When it comes to flexible packaging applications, where the film needs to conform to the contour of the product or container, this is an especially desirable feature.

Bringing Down the Costs and the Material Waste

Another advantage of using polymer adhesives in multilayer coextruded films is that they help to cut down on the amount of material waste and the amount of money spent. As a result of adhesives’ ability to facilitate the utilisation of thinner individual layers, producers are able to attain the needed qualities without experiencing an excessive amount of material consumption. The use of thinner layers results in films that are lighter in weight, which can contribute to cost savings in terms of the availability of raw materials and transportation.

Additionally, polymer adhesives make it easier to recycle multilayer films since they make it possible to separate the layers more easily during the recycling process. It is crucial for sustainability projects to do this since it encourages the reuse of resources and decreases the influence that anything has on the environment.

Modification of Properties to Accommodate Particular Applications

Due to the adaptability of polymer adhesives, producers are able to modify the properties of multilayer coextruded films in order to fulfil the unique requirements of a variety of applications. The choice of adhesive can have a considerable impact on the features of the final film, whether it be for the purpose of modifying the barrier properties for food packaging, boosting the printability for branding purposes, or strengthening the heat-sealing performance for easier opening.

When it comes to applications that include the use of heat sealing to form pouches or bags, for instance, adhesives that have a high amount of heat resistance and seal strength are very necessary. The use of these adhesives guarantees a robust seal that not only prevents leakage but also preserves the freshness of the goods. In a similar vein, adhesives that have outstanding printability make it possible to print logos, product information, and other components of branding directly onto the surface of the film in a way that is both colourful and of high quality.

Polymer adhesives are the unsung heroes of multilayer coextruded films because they play a crucial role in guaranteeing the functionality, integrity, and performance of these films during the manufacturing process. These adhesives are crucial components of modern packaging solutions because they fulfil a variety of functions, including providing strong adhesion between layers, strengthening barrier qualities, improving mechanical strength, and permitting customisation for specific applications.

It is impossible to overestimate the significance of polymer adhesives in multilayer coextruded films, since the need for high-performance packaging continues to increase across a variety of different industries. Manufacturers and package engineers rely on these adhesives to develop innovative and efficient packaging solutions that preserve products, increase shelf life, and achieve sustainability goals. These solutions need the use of adhesives.

Moving forward, developments in adhesive technology will continue to drive improvements in multilayer coextruded films, which will enable the packaging sector to achieve even greater levels of efficiency, functionality, and sustainability. When stakeholders have a comprehensive grasp of the function of polymer adhesives, they are able to make well-informed decisions that will increase the efficiency of packaging designs and satisfy the ever-changing requirements of customers and the market.

Coace® W1L serves as tie layer between those incompatible materials and makes high performing multilayer structures possible! COACE’s W1L is polyethylene as the base material grafted with MAH, and polar side groups are introduced into the non-polar chain. It is an adhesive for polar materials and non-polar materials. Greatly improve the adhesion between base resin and functional layer resin.