When it comes to current packaging solutions, multilayer coextruded films are an indispensable component. These films offer a combination of features, including barrier protection, strength, and flexibility. The selection of proper polymer adhesives, on the other hand, is a significant factor that determines the effectiveness of these films. The selection of adhesive is of the utmost importance when it comes to addressing the deficiencies and difficulties that are inherent in multilayer packaging materials. In the following paragraphs, we will delve into the complex process of selecting the appropriate polymer adhesives in order to improve the functionality and performance of multilayer coextruded films.

Having an Understanding of the Obstacles

Prior to delving into the process of selecting the appropriate polymer adhesives, it is of utmost importance to gain an understanding of the difficulties encountered by multilayer coextruded films. In addition to providing strong adhesion between layers, enhancing barrier qualities against oxygen and moisture infiltration, improving mechanical strength and durability, and permitting customisation for specific applications are some of the obstacles that need to be overcome. Polymer adhesives are an essential component in overcoming these problems and achieving the highest possible level of performance from the film as a whole.

When Choosing Polymer Adhesives, There Are Several Factors to Consider

When selecting polymer adhesives, the compatibility of the adhesives with the various substrates that are used in the production of the multilayer coextruded film is the primary factor to take into consideration because it is the first consideration. Materials such as polyethylene (PE), polypropylene (PP), ethylene vinyl alcohol (EVOH), polyamide (PA), and others might be included in this category of substrates. It is necessary for adhesives to be compatible with certain materials in order to provide high-quality bonding and avoid delamination.

Adhesion Strength: The adhesion strength of the polymer adhesive is an essential factor in ensuring that the multilayer film retains its integrity. The weight of the packaged product, the stresses that occur during handling and transportation, and the requirements for sealing can all play a role in determining the level of adhesion strength that is required for a particular application.

In addition, polymer adhesives have the potential to make a contribution to the overall barrier qualities of the film. Adhesives that have strong barrier characteristics assist seal gaps and spaces between layers, which prevents oxygen, moisture, and other pollutants from penetrating the layers. This holds a special significance for applications in which the freshness of the product and its shelf life are of the utmost importance.

Heat Resistance: Polymer adhesives need to have great heat resistance in order to be used in applications that need heat sealing, such as pouches and bags. This ensures that the seal is robust and long-lasting, which helps to preserve the product’s freshness and integrity while it is being packaged. It is possible for adhesives with low melting points to cause the seal to fail, which would bring the effectiveness of the package into question.

Flexibility and Elongation: Polymer adhesives that have strong flexibility and elongation qualities are attractive for use in applications that include flexible packaging. Because of these adhesives, the film is able to adhere to the contour of the product and retain its integrity even after being bent and stretched without ripping. It is especially crucial for applications like stand-up pouches and shrink sleeves to have a high degree of flexibility.

Possibility of printing: Certain applications necessitate the capability of printing directly onto the surface of the film in order to incorporate branding and product information. This is made possible by polymer adhesives that have a good printability, which allows for high-quality printing without compromising the adhesion or barrier qualities of the film. Consequently, this guarantees that the package will continue to be visually appealing and instructive.

Concerns Regarding the Environment:The packaging sector is becoming increasingly concerned about the issue of sustainability. When picking polymer adhesives, it is essential to take into consideration the impact that they have on the environment. Using adhesives that are either recyclable or compatible with recycling procedures is one way to contribute to a more environmentally friendly strategy for packaging.

Examples of Polymer Adhesives That Are Commonly Used

Due to its exceptional adherence to a broad variety of substrates, including as PE, PP, and EVOH, Ethylene Acrylic Acid Copolymers (EAA) adhesives are utilised extensively in the production of multilayer coextruded films. They have excellent heat resistance and barrier qualities, which makes them useful for applications that require strong bonding and a barrier against moisture and oxygen from the environment.

Polyethylene-based adhesives: These adhesives are suitable for use with PE substrates and offer a high level of adhesion strength. In applications where flexibility and seal strength are of utmost importance, such as flexible packaging for snacks and confectionery, they are frequently utilised.

Tie Resins: Tie resins are a means of increasing adhesion between layers by acting as a bridge between polymers that are incompatible with one another. As a result of their ability to ensure strong bonding and prevent delamination, they are frequently utilised in multilayer films that contain a variety of substrate materials.

Adhesives made of polyurethane Polyurethane adhesives have great flexibility and elongation qualities, which makes them an attractive choice for applications involving flexible packaging. They not only offer a strong binding, but they also ensure that the film is able to conform to the contour of the object without any compromise.

(MAP) Adhesives, which stand for modified atmosphere packaging:
For applications in which oxygen barrier qualities are of utmost importance, MAP adhesives have been customised to meet specific requirements. They contribute to the formation of a hermetic seal, which helps to maintain the quality and freshness of perishable goods like meat, cheese, and vegetables while they are stored.

Methods for Selecting the Appropriate Adhesive for Particular Applications
When choosing the appropriate polymer adhesive, it is necessary to conduct a thorough analysis of the particular needs that are associated with the packaging application. Just one example:

Applications such as fresh produce, dairy goods, and snacks require adhesives that have high barrier characteristics against oxygen and moisture. Some examples of these applications are food packaging. It is possible to use tie resins or EAA adhesives as viable options.

In the pharmaceutical industry, adhesives that possess strong adhesion, resistance to heat, and barrier qualities are required for packaging medications. This is done to ensure that the items maintained their integrity. It’s possible that polyurethane adhesives or MAP adhesives might be satisfactory.

Industrial Products: Adhesives that have a strong chemical resistance and durability are frequently required for packaging industrial products such as chemicals or electronics. Polyethylene-based adhesives or tie resins are two potential possibilities that could be considered.

Adhesives for multi-layer coextruded films

Coace’s W1L is a polyethylene-based material grafted with MAH, which introduces polarity into the non-polar chain.The side group is a bonding agent between polar materials and non-polar materials. W1L can play a connecting role in composite films of polypropylene, polyolefin and nylon. The amino reaction between MAH and nylon greatly improves the adhesion between the base resin and the functional layer resin.

EVOH has excellent barrier properties against gases and oils, and is resistant to oxygen, water, and dioxide. High barrier effect against carbon and odor.Since some base layer resins have poor affinity with functional layer resins, it is necessary to Some adhesive layers are placed between the layers to act as glue in order to create an “integrated”
composite membrane. The main material of COACE’s K2B 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.

Final Thoughts

For the purpose of overcoming the inadequacies and difficulties associated with multilayer coextruded films, it is essential to select the appropriate polymer adhesives during the manufacturing process. These adhesives are extremely important because they ensure a strong adhesion between layers, improve mechanical strength, enhance barrier qualities, and make it possible to customise the material for specific purposes. Manufacturers are able to select the adhesive that is best suited to meet their packaging requirements by taking into consideration a variety of characteristics, including compatibility with substrates, adhesion strength, barrier properties, heat resistance, flexibility, printability, and environmental impact.

Polymer adhesives will continue to play an essential part in multilayer coextruded films, despite the fact that the packaging sector is always undergoing significant change and innovation. The advancement of adhesive technology will result in future improvements in the performance of films, as well as improvements in their efficiency and sustainability.

For the purpose of overcoming the inadequacies and difficulties associated with multilayer coextruded films, it is essential to select the appropriate polymer adhesives during the manufacturing process. These adhesives are extremely important because they ensure a strong adhesion between layers, improve mechanical strength, enhance barrier qualities, and make it possible to customise the material for specific purposes. Manufacturers are able to select the adhesive that is best suited to meet their packaging requirements by taking into consideration a variety of characteristics, including compatibility with substrates, adhesion strength, barrier properties, heat resistance, flexibility, printability, and environmental impact.

Polymer adhesives will continue to play an essential part in multilayer coextruded films, despite the fact that the packaging sector is always undergoing significant change and innovation. The advancement of adhesive technology will result in future improvements in the performance of films, as well as improvements in their efficiency and sustainability. COACE provides multi-layer packaging film solutions. Welcome to discuss with us how to better improve packaging performance!