Drainage and Retention Improvement with Talc, 2003 Spring Technical Confernce Proceedings

Papermakers always welcome any improvement in drainage since it affects machine productivity. Drainage is particularly important on machines that have limited drying capacity and, therefore, slow speed. A slow draining stock limits the speed at which a paper machine can be run. It can also limit the extent of pulp refining necessary for paper strength improvement. Additionally, any improvement in retention or reduction in retention aid usage helps paper formation, among others, by reducing floc size. This is especially important in printing papers.

This paper presents laboratory results of studies on supercalendered and coated freesheet papers, which showed significant improvements in retention and drainage when talc was partially substituted for either clay or PCC. A combination of talc’s low anionicity, high hydrophobicity and large particle size attribute to improved machine drainage. Additionally, the large platy talc particles in the filler blend increased fiber and filler retention. By exploiting the positive effects of talc on drainage and retention, and its functional synergy with clay or PCC, a host of paper properties can be enhanced.