To ensure the safety, quality, and to protect consumers’ health, food packaging must be reliable and consumer friendly. For a paper-based food packaging product to be successful, it must be coated to perform additional functions. The main purpose of coating is to protect the product from the undesirable effects of factors such as light, oxygen, humidity, and microbes. Depending on the application, coating functions also include improved grease proofness, heat resistance or peel ability, or enhanced printing and finishing properties. Nearly 7 million tons of coated paper, paperboard and cardboard are manufactured worldwide annually.
Improving paper’s barrier properties is seen as a crucial step in increasing its viability as a packaging material. The missing performance and barrier properties of paper can be compensated by: 1) Wax treatment: curtain-coated, cascaded, impregnated 2) Extrusion coating/Lamination: Petro-based & Bio-based resin or 3) Water-based coating.
Petroleum-based wax has traditionally been used as a moisture barrier to protect the fibers, add strength and rigidity of paper-based containers. However, waxed packaging is raising recyclability, sustainability and renewability concerns. Growers and retailers are looking for alternatives to wax.
Extrusion is the most commonly used barrier coating technology. Extrusion coating allows processing a variety of polymers and board. Paper and paperboard (CRB, URB, SBS…). Low density Polyethylene (LDPE) is the most widely used material for extrusion coating applications: easy to process, provides adequate moisture barrier, has excellent sealing properties, grease resistance and lamination layer and cost competitive. Many kinds of carrier substrates can be laminated to paperboard to enhance barriers properties: Foil, clear and metalized film.
With the push towards sustainability, repulpability and recyclability, water-based technologies as an alternative solution to current wax, PE extrusion coating and film lamination, are gaining acceptance. Water-based coatings can be custom-formulated to meet the packaging requirements of a wide range of products. It is NOT “one-size-fits-all” solution. It is customizable considering the final application, the packaging process and the storage conditions.