For many years, food can be portioned through a packaging consisting of a PVC film

It is by now it is our habit to buy portions of food that the shopkeeper or large-scale distribution packs in a PVC film. Even in our homes, partial batches of food are commonly wrapped in these films to increase shelf life and safeguard quality.

Although there are also several PE films today, the PVC market is still the most important due to numerous techno-economic factors.

The use of PVC polymer allows to create a very resistant film, with a low permeability to water and oxygen, with a good resistance to acids and diluted alkalis.

Moreover, for a completely practical fact, the PVC food films have an excellent packaging capacity, easily welded to a plate or bowl or on itself. same.

From an economic point of view, the presence of chlorine in the PVC compound, essential for its chemical structure, significantly reduces the cost of the finished product. because there is an ethylene saving of about 50% compared to the use of PE for the same product.

Using PVC it is possible to insert a series of additives that can modify its performance characteristics, having the possibility of creating, with a single polymer, different products.

Let's see the main additives that are used in the packaging industry:

• Anti-blocking agents: reduce the tendency to adhesiveness

• Anti-fog agents: promote the formation of a homogeneous and continuous veil of liquid

• Antimicrobials: prevent the growth of microorganisms

• Antioxidants: They prevent the degradation of the film due to the atmosphere

• Antistatic: They reduce the accumulation of electrical charges that attract dust

• Swelling agents: used to produce foams from plastic materials

• Catalysts: they start the polymerization in the production of plastic resins

• Dyes: allow the coloring of the films

• Coupling agents: favor the coupling between pigments and polymers

• Flame retardants: reduce the flammability of materials that are combustible

• Heat stabilizers: reduce the degradation of PVC into hydrochloric acid

• Lubricants: Reduce adhesiveness between PVC and metal parts

• Plasticizers: improve flexibility, workability and expandability

All these additives, but especially the plasticizers, are subject to very strict regulations to allow their use in the food sector.

It must be considered that there are about 300 types of plasticizers on the market and those approved for food use, are subject to the hygiene regulations of packaging, containers, utensils intended to come into contact with food substances or substances for personal use.

The substances that could transfer from the packaging to the food can be divided into three categories:

• Added substances: mainly represented by the PVC additives listed above

• Residues: represent parts of polymeric material with incomplete reactions (monomers, catalysts, solvents, adhesives, etc.)

• Newly formed products: these are substances that originate from the spontaneous decomposition of materials or during operations of transformation into an artifact

These substances, defined as neoformations, are very variable among themselves, depending on many chemical-physical factors that can occur and that can affect the possible transfer of substances in the food that are difficult to manage and resolve.

Automatic translation. We apologize for any inaccuracies. Original article in Italian.