THE INCIDENCE OF THE DESTABILIZATION OF THE PULP SUSPENSION ON THE DEPOSITION OF SECONDARY STICKIES - NEW TEST SHOWS PROPENSITY FOR STICKIES FORMATION

Due to environmental restrictions, the closing of water circuits and t he increasing use of recycled fibres (with a lower quality of the wast e papers to recycle), paper makers have an increasingly difficult prob lem to solve: the deposition of sticky particles either on the sheet f orming fabric or on the press and dryer felts. These problems are ofte n very difficult for the paper makers to understand because they can a ppear without any visible change in the raw material or in the paperma king process variables. In this paper, after a definition of what are called secondary stickier, an attempt is made to analyse and explain t hese phenomena. The different changes occurring throughout the pulp pr eparation process and the wet end of the paper machine are reviewed, w ith special attention paid to the changes affecting the destabilizatio n of the pulp suspension, i,e., to the formation ol secondary stickies . The main characteristics involved in the stability of a pulp suspens ion are reviewed and a test method to characterize the potential of th e pulp or the process water to produce secondary stickies is presented . Results obtained with this new test show clearly the strong relation ship between destabilization and the formation of secondary stickies. Additional experiments show that the paper machine's wet-end chemistry also has a strong influence on the deposition.