Date of Award

4-1994

Degree Name

Bachelor of Science

Department

Paper Science and Engineering

First Advisor

William K. Forester

Abstract

Efforts to increase production capacity and meet recycled fiber content regulations include the utilization of recycled OCC as a fiber source. This fiber source is predominantly softwoods which are characteristically longer and stronger than hardwood fibers. However, the corrugating medium found in OCC contains mostly hardwood fibers which are shorter and more brittle than the desired softwoods. In addition, the medium contains a significant amount of lignin that interferes with fiber bonding. Therefore, the resulting paper web's strength is decreased.

The paper industry is forced to find ways to achieve maximum strength from an inferior starting material. One method under investigation is caustic soaking. This study investigates the effects of pH and soaking time on the recycling of OCC and attempts to identifying the optimum repulping conditions.

The OCC furnish was repulped at several pH levels. At each pH level, the stock was than soaked for various lengths of time. Subsequent testing of the pulps and handsheets, and analyses of the results were completed in order to determine the above mentioned objectives.

The effects of pH and soaking time on the OCC pulp and resulting handsheets are discussed in this report. The optimum repulping conditions were determined to be at a pH of 9 and a soaking time of 5 to 10 hours. Statistically significant strength increases in the handsheets produced at these optimum conditions were found to range between 5 and 19 percent for the various tests performed.

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