Choice of paperboard
A package must, whatever it contains, look attractive to the consumer. Tubs, particularly, should have an appetising and attractive shelf appeal, so that the product singles itself out from surrounding products at the point of sale. Cups, especially those sold with hot or cold drinks in fast food outlets, often carry a striking logo. Cups and tubs must maintain the highest standards of hygiene. This is crucial, since in many applications the container cannot be examined by the customer prior to the consumption of the food or drink.
Important characteristics are whiteness, smoothness and surface finish. Good contrast between the surface of the paperboard and the print is required to achieve good presentation of printed text and illustrations in bold colours. The graphical presentation and hygienic appeal call for pure virgin fibres. Strength and toughness are required for the overall shape and forming of the rim. For cold drinks dispensed in large cups there is a risk of moisture condensing on the paperboard, reducing its strength and causing distortion when handled. The use of 2-side PE coated board should be considered for these cups. For small drinking cups, though, 1-side PE coating is usually satisfactory.
The main protective feature of cups and tubs is that they must be leak-proof and rigid. This is achieved by using 1 or 2 side PE coated paperboard with the required strength and toughness for forming and heat sealing. The stiffness must ensure stability and safe handling for even the largest cups and tubs.
High compression strength is required to keep the cups and tubs safe from physical hazards in distribution, storage and handling at the point of sale. For drinks and other liquid or semi liquid products, paperboard with resistance to edge absorption is required.
Strength, toughness and stiffness are the main properties for the functional shape of cups and tubs. A smooth surface provides for ease of handling, good rub and abrasion resistance, thereby preserving the graphical presentation. The preservation of aroma and flavour is provided by the use of pure virgin fibres and approved coatings and additives. Product safety - since the product is in contact with the paperboard - is achieved by the use of pure virgin fibres and approved coatings and is validated by meeting internationally accepted standards of safety, e.g. compliance with international food contact legislation.
Printing and conversion
To obtain efficiency in printing and conversion a flat, stable and dust free paperboard is required. Good absorption and drying are important to ensure a high print quality, whilst process stop pages and material waste are minimised.
Cups and tubs can be straight sided or tapered. Tubs can have various types of closure - heat sealed diaphragms or pressed on lids in paper board or plastic. Manufacturing machines for cups and tubs run at high speeds and the material, supplied in reel form, must possess sufficient strength for easy forming and shaping, as well as a functional coating of PE for quick and reliable heat sealing. Tubs can also be formed from pre-printed sheets. The forming of the rim and the bottom of these containers requires a strong and tough paperboard which will not rupture.