Abstract
In the Japanese pulp and paper industry, the progress of closed white water system and the growth in the use of waste paper have made the papermaking conditions worse: the increase of spots on forming fabrics, press felt and dryer fabrics as well as deposits on press section pickup rolls and Uhle boxes, and calender stacks has consequently brought about the short-time replacement of fabrics and felt, sheet picking, wet web breaks, and dirt specks and holes in the finished product. These deposits cause so-called “pitch troubles”.
The nature and severity of these troubles vary with type of mills (newsprints, fine paper, board, or tissue manufacture) and the levels of recycled content in the furnish. In order to devise a suitable control strategy, a more thorough knowledge of the chemical composition of the pitch should be needed. The chemical analysis of the pitch samples obtained from paper mills has indicated that the major sticky components are generally wood resin components originationg from virgin and waste pulp, and artificial polymers from the waste papers.
This article describes characteristics of a new type of the organic pitch-controlling agent, MRT-series, and a novel approach to control the pich troubles. The MRT-series consist of zinc stearate with specially formulated cationic surfactants and produce several effects to papermaking processes: reduction of the tackiness, covering the stained materials, and so forth.
