Folding carton packaging buyers have to make decisions on the choice of the carton that will impact the cost and the quality of the final product. Choice is often between SBS board and FBB.
Type of bleached board for folding carton packaging: SBS board or FBB?
SBS board (Solid Bleached Sulphate) is exclusively manufactured in North America. During the pulp manufacturing process, the fibers are separated and the lignin is dissolved in an aqueous solution with the appropriate chemicals. The pulp is then bleached. Using a chemical process at this stage will leave the fibers at their full length, increasing the strength of the board.
SBS board is made only with chemically processed fibers. It can be single or multi-ply.
FBB (Folding Box Board) board is a multiply carton board manufactured all over the word except North America. Outer plies are made of bleached chemical pulp, just like SBS board. The difference lies in the inners plies since they include mechanical pulp layers. The mechanical process separates the fibers using a sort of a grind. Heat can be used and it is then called thermo-mechanical pulp. Some chemicals can also be added to facilitate the process. It is the called Chemi-Thermomechanical pulp (CTMP). In the mechanical process, no effort is made to remove the lignin from the fibers. During the CTMP process, a fair amount of the lignin is removed.
Stiffness : FBB vs SBS
Stiffness is a very important property when considering choosing a paperboard. Stiffness will determine the choice of the board grade and thickness for the chosen application. Ideally, the board to be chosen should be the one with the higher stiffness for the lowest weight and hence cost. Stiffness is always given for 2 directions: Machine direction (MD) and Cross direction (CD). Stiffness measures the resistance of the board to bending. The most common data is the Taber 15o. A 38 mm is clamped at one end and a force is applied the other until it reaches a 15 o angle. The value is expressed in mNm.
If one thing needs to be remembered from this post, choosing the right board for your folding carton packaging is not an easy thing and a close collaboration with the packaging converter is essential.
Data Source: Metsa, APP, Westrock, IP, GP