Reduction of pitch deposit troubles by coagulant derived from waste corrugated board

Abstract

In paper manufacturing process, the formation of colloidal pitch particle is an important matter that affects the runnability and finished product quality. Pitch deposit troubles caused by stickles in the recycled waste pulp have been increased with increasing the usage rate of recycled waste paper. Especially, pitches of polyacrylate esters derived from adhesives used for labels in the door-to-door delivery services have been drastically increased for the last several years. This type of pitches is frequently found on the drier rolls and canvases. Four different types of our coagulants were evaluated in the liner mill which has pitch trouble derived from polyacrylate ester. These coagulants were effective in the reductions of the amount of pitch on the drier doctor, defects in the paper, and also turbidity and anionicity of white water, irrespective the kinds of coagulants. Evaluations of the coagulants above were carried out in our laboratory in order to study mechanism of pitch formation and effects of the coagulants with the use of model pitch. Polyacrylate ester extracted from adhesive tape with THF was used as model pitch. The results showed the coagulants are effective in preventing pitch agglomeration of this model pitch. However, the action mechanism of the coagulants may be different, depending on their types, from the results of measurement of pitch particle size and its distribution by in-line particle monitoring system.