The Effect of Surface Pretreatment on Binder Penetration in Coated Board

A study was performed to determine the effects of surface size pretreatments on binder penetration into coated board. Sixteen point board was sized with water, oxidized starch, polyvinyl alcohol and a 20:1 mixture of the two utilizing the blade coater. This treated board was then coated with a latex-clay coating on the air knife coater. Testing of the board samples showed that the coated board pretreated with the oxidized starch had the best surface strength and ink hold-out characteristics. This was followed by the mixture and finally by the polyvinyl alcohol. The coated board with no surface size had the worst strength and printing characteristics, while the water pretreated stock was slightly better but worse than the three surface sizes. It is theorized that the results of the study are related to depth of penetration of the surface size employed. Due to lower solids, less viscosity and different chemical structure, it is felt that the polyvinyl alcohol may have penetrated deeper into the basestock than the oxidized starch. Therefore with this deeper into the basestock than the oxidized starch. Therefore with this deeper into the basestock than the oxidized starch. Therefore with this deeper penetration, the surface size would be less effective in keeping the coating binder near the surface. This could result in lower surface strength and less ink hold-out