Drying Strategies and a New Restraint Technique to Improve Cross-directional Properties of Paper

Abstract

Machine-made papers often have an unsatisfactory cross direction profile with regard to their mechanical properties. The edges often have a lower strength and stiffness than the middle of the web.

Laboratory studies of the behaviour of paper during drying have shown the potential of improving CD properties without any deterioration in MD properties. This is achieved by preventing paper shrinkage in both directions during drying.

After extensive trials on a full-size paper machine equipped with a new cross-direction restraining technique, it has been demonstrated that the laboratory results can be repeated in a continuous process. This invention has the potential of solving some old problems in papermaking such as evening out the cross-direction profile and improving strength and stiffness properties, dimensional stability and surface properties.