In this master's thesis, we wanted to determine the impact the grinding and removing of the coating of the cardboard has on the strength of adhesion between bonded test pieces of coated cartonboard. We carried out several different ways of damaging the coating, so that the glue could be better absorbed into the cardboard. This would improve the strength of the adhesive bond and prove that investments in this component of the gluing machine is important.
The measurements were performed on different grammars of one type of coated catronboard. To grind the coated cartonboard, we had to develop a procedure that could evenly brush or remove the coating. We tested three methods: modified grinding method on the abrasiometer, grinding carried out on a dynamometer using a grinding tape and grinding method that uses an electric drill and a grinding brush. The coating was successfully damaged and removed, the matrix of fibers has only began to damage, as can be seen on the SEM shots. Damages to the cartonboard were made in the width of the application of the adhesive and only in the place where the adhesive was later applied. Doing this, we maintained the strength of the cartonboard, while at the same time allowing the adhesive to immediately come into contact with the fibers and thus be easily and more deeply absorbed into the cardboard. The glued samples were then torn using a modified T-test method on a dynamometer. If a good fiber cracking occurs, the adhesive bond can be labelled as successful. Damaged samples with silver wire brush gave us excellent results, as we increased the mean strength by as much as 10 N. The results of our experiment have confirmed our hypothesis that deliberately damaging or removing the coating improves the strength of the adhesive bond.
In this master's thesis we modified one of the methods for determining the split of glued samples and consequently obtained a repeatable method for measuring the force required for the tear on dynamometer.