A new repulping process that uses a nonchlorinated oxidizing agent and
a rewetting agent was found to be very effective in repulping wet-str
ength paper that was difficult to break down. The process is particula
rly useful in repulping unbleached paper and old corrugated containers
(OCC) containing polyaminoamide-epichlorohydrin (PAE) wet-strength re
sins. The process involves oxidizing the wet-strength paper at a low p
H with inorganic or organic peroxides followed by hydrolyzing the wet-
strength paper at a high pH. In field trials, unbleached paper contain
ing high levels of PAE resins was repulped to about 95% in mill hydrop
ulpers. This process enables papermakers to defiber unbleached paper a
nd OCC more efficiently than commonly practiced neutral or alkaline re
pulping processes.