Improvement of SB-Latex for Web Offset Coated Paper, 1991 Coating Conference Proceedings

It is mentioned in this paper that the improved SB-latex can provide good balance between picking strength and blistering resistance for web offset printing coated paper. According to conventional method, good picking strength or good blistering resistance to latex is controlled by gel content. However, reducing gel contents can give good blistering resistance by making the coated layer porous but the porous structure then causes poor picking strength, and vice versa. It is difficult to reconcile blistering resistance with picking strength only by controlling gel contents. From the study of how gel content affects the coating structure due to the polymer melt flow behavior to temperature relation in latex, the quality of gel is changed to provide greater thermal sensitivity to the melt flow of latex polymer. This sensitivity results in a small pore coating structure which gives good picking strength and a large deformation of pores under high temperature which gives good blistering resistance. Consequently, Thermal Sensitive Latex (TSL), which has higher homogeneous molecular weight distribution and carboxyl group distribution, is developed and it can provide good performance between picking strength and blistering resistance by it’s unique melt flow behavior.