The Use of Borax to Inhibit the Brightness Reversion of Bleached CTMP

This thesis evaluated the ability of Borax to inhibit the yellowing process of paper that was made from bleached chemithermomechanical pulp (BCTMP). Paper made from BCTMP has a tendency to lose brightness (photoyellow) when exposed to ultra violet (UV) light. The light initiates a series of chemical reactions to take place that results in the formation of yellow ketone and quinone products. A combination of boric acid and borax was applied to the surface of the paper to interfere with these chemical reactions and prevent the formation of the yellow products that cause photoyellowing. The effectiveness of these additives was also compared with a previously used inhibitor (ascorbic acid). Borax was only effective at inhibiting brightness reversion when it was added in combination with boric acid. The boric acid worked almost as well as the ascorbic acid when used alone. When the two were used in combination the effects were increased with an equal addition level of the additives individually