Date of Award
Bachelor of Science
Paper Science and Engineering
Soy protein is commonly dispersed with NH4OH, which is a volatile alkali driven off during the drying process. This creates a potential health hazard. Sodium hydroxide, which does not vaporize, can be used to disperse the protein. However, when using it, it is difficult to develop water resistance. This project is designed to find an additive that when used in conjunction with NaOH dispersed proteins will produce a water resistant coating.
Four insolubilizing agents: melamine formaldehyde, ammonium zirconium carbonate, glyoxal, and sunrez 700FF, were tested with 2.5-3.5 and 5% NaOH dispersed proteins, while a 15% NH4OH dispersed protein was used as a control. The prepared coatings were then tested for variations in pH, viscosity, brightness, dry pick, wet pick and wet rub.
At the levels recommended by the manufacture of the four insolubilizers tested, none produced both wet and dry pick results without a large increase in viscosity.
Coatings insolubilized with glyoxal has an intolerable viscosity increase. Brightness also decreased with its use. However, glyoxal did produce the best wet pick and wet rub resistance when used with the NaOH cut proteins.
The lowest viscosity NaOH dispersed protein coatings were insolubilized with AZC and wet rub resistance increased with increasing levels of this insolubilizer.
Protein dispersed at the 3.5% NaOH level produced the best dry and wet pick results, while the 2.5% NaOH dispersed protein gave the best wet rub results within the NaOH cut proteins.
Because wet rub improved with increased levels of AZC for the NaOH cut protein coatings, it should be possible to obtain the wet rub results required by increasing the level of AZC.
An alternate solution to the ammonium problem would be to reduce its level rather than eliminating it completely. This might be accomplished by using a combination of NaOH and NH4OH to disperse the protein.
Rock, Jon, "A Comparison of Insolubilizers for NaOH Cut Protein Coatings" (1982). Paper Engineering Senior Theses. 381.