Method of rigidifying the tearing edge of a carton

摘要

A tearing edge is formed at an edge of a paperboard blank according to the present invention by arranging a plurality of paperboard blanks in a stack with the edges which are to be reinforced disposed in a common plane and applying a clamping force to the stack of blanks and applying to the edges which are to be reinforced a coating fluid of a type which is at least semi-rigid when set and allowing the coating to set to form a rigidifying edge and thereafter releasing the clamping force to permit separation of the blanks from the stack.