Date of Award


Degree Name

Bachelor of Science


Paper Science and Engineering


Flexographic inks are rapidly gaining popularity in the printing industry for reasons of both safety and environmental concern. These relatively new water based inks, however, are presenting some very difficult challenges for traditional flotation/fatty acid deinking methods. Problems arise because water based flexo ink disperses in alkaline conditions and the resulting ink particles tend to be extremely small (0.2-1.0μm) and highly hydrophilic (water loving). One possible solution to increase deinking efficiency is the use of an organophilic clay such as bentonite during the flotation process. The objective of this project was to repulp 100% flexographic printed newspaper and deink it using a laboratory flotation cell. Trials were conducted using increasing amounts of kaolin and bentonite clay (5%, 10%, and 15% based on O.D. fiber).

The substitution of bentonite clay during the flotation deinking process showed significant improvements in brightness as solids levels were increased. At 15% solids a Δ brightness of 10.7 was obtained with bentonite 670 compared with a Δ brightness of 1.8 with KWW (kaolin clay).