Date of Award
Bachelor of Science
Pulp and Paper Technology
It has been recognized in the past that certain means of dispersing titanium dioxide in paper yielded better results. An optimum dispersion is one that results in the best optical efficiency of the pigment in the sheet.
In an attempt to pinpoint the optimum conditions the following facts were revealed. Increased mechanical action on the stock slightly increases the brightness and opacity. Pigment addition to higher consistency stock increases brightness and opacity considerably. The alum agglomerated impurities of soft water slightly increase opacity and decrease brightness in unpigmented papers; do not appreciably change the optical properties of pigmented sheets. Untreated water probably would magnify the effects. Excessive use of pigment dispersant, or alum is detrimental to brightness and opacity. Neither the order of addition of alum and pigment, nor extending the time of mixing measurably change the optical properties.
Certain factors affecting the dispersion of titanium dioxide in paper were revealed, but certain other mysteries about the pigment-fiber relationship still remain. Other means must be found to resolve them since small deviations and variations in handsheet formation and analysis are unavoidable, and tend to obscure results.
Gallagher, Michael James, "The Dispersion of Titanium Dioxide in Paper" (1968). Paper Engineering Senior Theses. 254.