Alkyl Ketene Dimer Wet End Hydrolysis in Alkaline Hardwood Furnish
Alkyl ketene dimer hydrolysis in alkaline hardwood stock converts active sizing wax into unreactive dialkyl ketone, raising chemical costs and felt deposits.
Oxetane Ring Cleavage
Polymerization Rate
Acid-catalyzed polymerization reactions open four-membered heterocyclic ether rings to form dense crosslinked ether networks. Within cationic radiation-curable inks and coatings for folding cartons, oxetane ring cleavage drives low-shrinkage polymer network formation under ultraviolet light. Superacid photoinitiators generate reactive cationic species that protonate the oxygen atom, triggering ring opening and rapid propagation with adjacent monomer molecules.
Cure Propagation
Cationic UV curing mechanisms exhibit dark reaction capabilities that allow polymerization to continue after the substrate leaves the ultraviolet lamp station. Unlike free-radical acrylate systems, oxetane ring cleavage proceeds without inhibition from atmospheric oxygen, yielding hard, chemical-resistant varnish coatings on food packaging board. Ring strain in the four-membered oxetane structure releases energy upon ring opening, driving high monomer conversion rates even in thick coating layers.
Low volumetric shrinkage during ring opening maintains strong adhesion to non-porous coated paperboards and metallized film laminates. Humidity levels inside print facilities must be controlled because excess water molecules scavenge propagating oxonium ions, terminating ring-opening chains prematurely.
Film Adhesion
High conversion rates eliminate residual unreacted monomer species that might migrate through packaging substrates. Low internal stress prevents coating curl on thin paperboard stocks. Effective oxetane ring cleavage establishes high solvent resistance and mechanical durability on printed packaging materials.