The use of hollow sphere pigments as strength additives in paper and paperboard coatings-Part 2: Optimization in paperboard formulations for opacity and strength

摘要

This report aims to summarize the efforts in testing the properties of coatings for paperboard utilizing hollow sphere pigments(HSPs).HSPs are known to effectively scatter light and replace titanium dioxide(Ti02)in architectural coating formulations.The effect of the particle size and void fraction was evaluated,along with many coating parameters,including level of addition,binder chemistry,and blends oftwo HSPs.The small HSPs that have optimized voids for scattering light showed equivalent strength to the TiO2-containing control.The strength data was surprising,particularly the improvement in strength for coatings containing large particle size HSPs.Because of this increase in strength,four parts of binder could be removed,which allowed for higher brightness while not compromising other properties,including hot melt glueability These trends held true using different binder chemistries(styrene acrylic,vinyl acrylic,and styrene butadiene).Upon refining the formulations further,blends of two HSPs showed further benefit.Application: This work shows that replacement of TiO2 with hollow sphere pigments can improve the balance of physical properties of paperboard coatings.By utilizing large particle size HSPs,one can replace TiO2 and reduce binder levels while maintaining brightness,strength,and other critical properties.