To attain specific properties, paperboard is combined with various plastics, films, foils or other additional paperboard layers. Complete descriptions of the product can be acquired by studying the specifications of the coating together with the specifications of the paperboard product. The choice of material is determined by the desired properties. These can be barriers against moisture and grease, heat tolerance, strength or combinations of these qualities.
Iggesund Paperboard’s developers often participate in customers’ packaging development, thereby acquiring a broad overview of packaging solutions. Our developers have gained an indepth knowledge of various material combinations and ways to optimise the performance of an end product. This knowledge can help determine the best solution for the product’s journey through the distribution system from manufacturer to consumer. In addition to what is presented in the catalogue, there are products available for various lid applications, end-use areas in which pigmented polymers and unique combinations of paperboard can prove useful. Contact your local Iggesund Paperboard representative for more information.
By using paperboard as a carrier for the plastic, the amount of plastic used can be reduced to about a fifth of what would have been required for an equivalent plastic container.
The surface finish of a plastic coated printing surface is determined by the smoothness of the baseboard and by the amount of plastic applied. A smooth baseboard together with a high gloss chill roll and enough plastic results in a smooth printing surface. The coated surface is subjected to chemical modifications by corona treatment to achieve good ink wetting. The finished surface can be damaged by handling, friction, high stacking, fingerprints, etc. When printing on a plastic or foil coated surface special inks are required. You should consult your ink supplier.
The finish on the reverse side of plastic coated products is NSO (non-set-off). This means that the plastic surface has small elevated spots. This is achieved by the use of a chill roll with a special surface. The resulting point contact with the underlying sheet ensures low friction and facilitates quick drying and avoids set-off. For plastic grammages below 15 g/m², the function of the NSO finish is successively reduced. To minimise the risk of blocking in printing and converting processes, avoid plastic grammages below 15 g/m² on the reverse side of products coated on both sides. One-side plastic coated board is usually corona treated to improve the sealing characteristics and to permit gluing with water-based adhesive.
Immediately after being manufactured, the finished paperboard is packed in a moisture-proof wrapper. The wrapper offers satisfactory protection against moisture changes, but only as long as it is left on intact. Leave the moisture-proof wrapping on until where the paperboard is to be converted. Two-side plastic coated board will tend to stick together if exposed to high pressure and/or temperature, leading to friction blocking problems. If the corona treatment is damaged reduced wetting with printing inks may result. Since the corona treatment is influenced by handling and storage conditions we recommend that the material is used within six months after production.
Plastic coatings are used on paperboard to give a protection against wet or aggressive products and to provide a barrier against moisture loss and gas transfer. The construction of the package and its closures is in many cases the factors which limit for the total protective function of the package.
The shelf life of the packed product depends on parameters such as:
- Quality and geometry of the product
- Filling level in the package
- Exposed area of the product
- Chemical properties of the product
- Storage conditions
When selecting a suitable protective plastic barrier it is necessary to refer to previous experience with similar packing requirements and also to consider the specific barrier. Typical values for our most common plastic coatings are tested according to ASTM F-1249/ DIN 53122 (water vapour permeability) and ASTM D-3985/DIN 53380 (oxygen permeability).
Typical barrier values
Overview functional properties
Usage range and melting range
of plastic coatings
Click to enlarge images.
Properties of plastic qualities