CD Laboratory for Fiber Swelling and Paper Performance

Papers for industrial printing or for packaging must be particularly absorbent and at the same time dimensionally stable and tear-resistant. The aim of the CD Laboratory is to scientifically describe these performance characteristics and to develop improvement concepts.

The primary aim of the research is to record and explain the basic mechanical processes in the paper fibres during the absorption and desorption of liquids, such as printing ink. In high-speed inkjet printing, the swelling processes within the paper fibres after application of the ink and during drying are particularly relevant. On the one hand, fibre swelling should be kept to a minimum and thus the drying time kept as short as possible; on the other hand, it is known that fibre swelling gives the paper more strength. An optimum balance must be found here for the degree of swelling of the paper fibres. Moistening by the ink also leads to deformation of the paper, such as bulging and curling. This should be prevented and the so-called flatness improved. As part of the research project, mechanical models of the exact swelling processes when the paper is moistened and dried are to be created. These models will then be used for simulations as part of the development of new high-speed printing machines. Fibre swelling also has an influence on the mechanical properties of the paper, e.g. strength and bending stiffness. These properties mainly depend on how strongly the swollen fibres bond with each other during the manufacturing process.

Based on the knowledge gained, concepts for modifying fibres and paper to improve their performance characteristics will be developed and models for mechanical simulation of the paper will be created for printing machine development.