Paperboard Creasing Mechanics and Physical Quality Inspection Fundamentals
Optimizing rule depth and matrix channel width induces internal ply delamination, preventing top liner crack failures during high-speed carton folding.
Cross Linked Network
Molecular Structure
Chemical structures form three dimensional bonds between polymer chains to create a stable resin matrix. The development of a cross linked network occurs during the curing phase of inks and coatings to provide chemical resistance and physical durability. These bridges prevent the molecules from sliding past one another when exposed to heat or solvents.
Solidification happens almost instantly in radiation cured systems.
Reaction Mechanism
Initiators absorb energy from ultraviolet lamps to create reactive sites on the polymer backbone. Within this cross linked network the density of the bonds determines the final hardness of the surface. Highly reactive monomers increase the speed of the bond formation but may lead to brittle coatings.
Low migration inks require a very high degree of completion to prevent unreacted components from moving through the substrate.
Functional Performance
Rub resistance improves as the density of the interchain connections increases. A stable cross linked network protects the printed image from scuffing during transit and prevents the ink from transferring to the back of the next sheet in the stack. Flexibility is maintained by balancing the length of the polymer segments between the bond points.
Excessively tight networks can cause the coating to flake off when the board is folded.