Development of Wet Process Mimic Device, 1999 Nonwovens Conference Proceedings

Daojie Dong, Ph. D.

Owens Corning Science & Technology Center

Drainage and the fiber bleed-through (FBT) are very important variables for the wet process. While there are several methods that can be used to evaluate the drainage-retention characteristics of papermaking furnishes, these methods are not suitable for the fiberglass slurries used in the wet process. This paper reported a wet process mimic device (WPMD) that is specially designed for the fiberglass slurries. The WPMD is capable of (1)mimicking a wet process, (2)measuring the rate of drainage, (3)quantifying the amount of FBT and (4)comparing the performance of various forming fabrics under simulated dynamic conditions. With some minor modifications, the WPMD is expected to have additional functions for (5)studying the shearing and aging effect on white water and (6) (possibly) evaluating the wear resistance of a forming fabric under simulated dynamic conditions.

The drainage experiment has shown that, in a gravitational flow field and with a commercial forming wire in position, the presence of small amount (~10ppm) of anionic polyacrylamide (PAM) assisted in the formation of streamlines and slightly increased the drainage rate of water. At higher concentrations, it reduced the rate of drainage significantly. The presence of fiberglass strongly affected the rate of drainage. At a PAM concentration of 165ppm, the drainage rate of pure water was reduced to ~50%; at a PAM level of 66ppm and a fiberglass consistency of 0.018%, the drainage rate was reduced to 31%.

The FBT experiment confirmed that a small fraction of long fiberglass (up to 1.25 inches long) did “bleed through” the forming wire. For a typical wet process line operating at a line speed of 600 fpm, it was estimated that about 21 pounds (~9.5kg) fiberglass would penetrate through the forming wire per hour.