The concept of monolayer plastic packaging is normally taken as synonym of single-material and multilayer plastic packaging as several materials. We talk about monolayer packaging when it is manufactured with a single layer of polymer, and multilayer packaging when manufactured with different materials joined into a sandwich-like structure.

To understand the existence of these complex structures in the manufacture of a plastic container, we must not forget that the packaging must fulfil basic functions, such as containing, protecting and preserving, promoting usability, handling and transportation, providing information about its contents and, ultimately, facilitating the sale of the product it contains.

When it comes to multilayer packaging, its function of properly conserving the product it contains, being resistant not to get deteriorated when coming into contact with certain substances and being easy to use and transport becomes the target in itself. Combining different materials into a multilayer plastic container (made of several layers and several materials) is one of the ways the plastic processing industry has found to maximize all the product preservation properties needed in a plastic container.

Differences between COEX packaging and HDPE packaging

If we talk about sustainability, recyclability is the main feature that differentiates the HDPE monolayer packaging from the COEX one. HDPE's monolayer packaging is made of one material (HDPE) only, being thus 100% recyclable. In fact, monolayer packaging in Spain is considered to have the highest percentage of recyclability. This does not mean that a COEX container is not recyclable, but it is true that we must move from mechanical recycling to a chemical recycling process, to separate the materials that make up its multilayer structure.

But this is not the only feature that sets them apart. Their structure and properties are very different if we take care of the components. As mentioned above, a packaging considered an HDPE monomaterial may also have a multilayer structure, but it will still be composed of a single type of material. This type of multilayer structures made of a unique polymer is mainly used to incorporate recycled material. HDPE is a very light material, with electrical insulation properties and resistant and flexible even under low temperature conditions, opaque and colourless. At Alcion Packaging Solutions we manage to incorporate up to 75% recycled material into our packaging, according to our commitment to contribute to the circular economy.

However, the packaging known as COEX multilayer combines several layers of different plastics materials, one of them with barrier properties. Therefore this type of container is ideal to preserve plant protection products inside without suffering from deterioration. This packaging is resistant to contact with chemicals, to solvents and to high temperatures and provides as well, protection against UV rays.

The co-extruded plastic container or COEX has emerged in response to the need to use packaging such as HDPE but with properties that act as a barrier to oxygen, water vapour, certain chemical reactions, etc.

Until the arrival of co-extrusion technology, there was no single-layer packaging that presented these characteristics and properties on its own, and that's where co-extrusion becomes important. This technique allows to overlap several layers of polymers in a single structure to provide the packaging with all these barrier properties, being one of the layers of EVOH (ethylene vinyl alcohol), or PA (polyamide), materials that provide the barrier properties to the multilayer container.

How to choose the right packaging?

The characteristics of each type of packaging make each one suitable for certain products but not for others.

In the case of HDPE, its properties such as low water absorption, fuel resistance, impact resistance, acid resistance, opacity and lightness, make packaging made with this material the most suitable for certain industrial chemicals such as detergents or chlorine, everyday products such as bleach and other cleaning products and some fertilizer and biostimulant products used in the agricultural world.

On the other hand, COEX plastic packaging is preferred for plant protection and agrochemical products such as pesticides and other aggressive chemicals and in food packaging for its conservation capacity thus avoiding the use of added preservatives, resistance to high temperatures and protection against ultraviolet rays.

At Alcion Packaging Solutions we have 75 years of experience in the plastics processing sector, so if you need a customized solution for your product, do not hesitate to contact us. Our experts can help you find the packaging that best suits your needs.