1. Basic principle

The basic principle is simple: each layer (or support material) of flexible packaging has specific properties (permeability, mechanical strength, printability, visual appearance, etc.). Using additional materials (adhesives, waxes, etc.), the various layers are joined together to create what is known as a structure. The ultimate aim is to create a structure with the characteristics contributed by the different layers. These characteristics are deemed necessary for the packaged product, or for the function requested by the consumer (figure 1 ).