Development of a functional filler: swelling sericite.

APPLICATION: This study could offer paper mills the choice of a new functional filler to stabilize the wet-end system and enhance retention of fines, fillers, and chemicals. Paper formation, thickness, air permeation, and smoothness could also be raised.

Sericite is an indigenously produced mineral from eastern Taiwan. As a mineral of the mica family, it is a naturally swelling, layered material. It possesses a high degree of negative charge and high aspect ratio, making it suitable for use as a functional filler to strengthen the retention of fines and chemicals in the wet-end process. This study investigated the use and development of swelling sericite as a functional papermaking filler in both acidic and neutral sizing systems. The study included laboratory tests and on-machine tests on paper machines of different speeds (below 300 m/min, 500 m/min, and more than 1000 m/min). We studied the effects of adding sericite on wet-end performance and paper properties. In the neutral sizing system, when 3% of calcium carbonate was replaced with sericite, the sizing degree improved by 46%, ash content by 18%, bulk by 4%, and opacity by 1.5%; but brightness was lowered by 1.5% ISO. In the acidic sizing system, when 3% of clay was replaced with sericite, the sizing degree improved by 85%, ash content by 13%, bulk by 4%, and opacity by 1.2%. Brightness was lowered by 1.5%. Regardless of machine speeds, sericite addition in the on-machine tests not only enhanced first pass retention, but also lowered flow rates of retention aid, sizing agent, and filler. In the high-speed machine test, sericite helped to improve the thickness, formation, air permeation, and roughness of the products. View this paper online at http://www.tappi.org/index.asp?pid=29480

Yuan-Shing Perng is with Da-Yeh University, Department of Environmental Engineering, 112 Shan-Jiau Rd., Da-Tsuen, Chang-Hwa, 51505, Taiwan; email [e-mail]. Eugene I-Chen Wang is with the Taiwan Forestry Research Institute, Division of Wood Cellulose, 53 Nanhai Rd., Taipei 100, Taiwan; email [e-mail].