Impact of press roll adhesion on paper machine runnability and sheet quality

摘要

There are many factors that can influence web release. An on-line laser camera is therefore a useful tool when studying the subject. In order to improve understanding of web release it is also important to relate changes in release point to process changes. In many cases it is difficult to establish what is the cause and what is the effect. It is therefore also critical to study the fundamentals of web release under well-defined laboratory conditions. Although the wet web peel tester has its limitations in terms of operating under static conditions and the use of handsheets rather than a machine-formed web, it has been possible to relate laboratory findings to actual machine observations. The increase in work of adhesion with higher DIP content, demonstrated with the peel tester, is experienced on the machine as well. However, other parameters such as the impact of wet end chemistry are more difficult to study under laboratory conditions. Impact of release aids that act mainly by deposit prevention is also extremely difficult to simulate under laboratory conditions but this is the subject of current studies.