Date of Defense
The objective of this work was to evaluate the influence of coating viscosity on the migration of latex binder during drying. Clay/latex coatings were applied to paper basestock with a Keegan coater. Latex migration was induced with hot air impingement. Surface latex concentration was measured using an ultraviolet absorbance technique.
Bentonite and glycerol were used to increase the coating viscosity. Bentonite adsorbed water molecules, reduced the effective volume of the continuous phase, and increased coating viscosity. Glycerol Increased the viscosity of the continuous phase, and, consequently, increased the viscosity of the coating. Viscosity increases by either of these techniques had no influence on the surface latex concentration.
Polyvinyl alcohol (PVA), carboxymethylcellulose (CMC), and sodium alginate were also used to increase coating viscosity. Viscosity increases due to these polymer additions resulted in a significant reduction in the surface latex concentration.. The order of their effectiveness at reducing surface latex concentration was alginate > CMC > PVA.
The polymeric nature of these last three additives may have been the significant factor influencing the inhibition of latex migration. Differences in their electrostatic characteristics may account for the varied effectiveness of the different polymers.
Apparently, polymer addition to paper coatings will inhibit latex migration, but higher coating viscosities will not.
Bushhouse, Steven G., "The Effect of Coating Viscosity on Surface Latex Concentration" (1990). Honors Theses. 736.
Honors Thesis-Campus Only