ENVIRA® E-221 is an amphoteric dry strengthening resin, specifically developed to increase the strength properties of paper and paperboards. As an amphoteric poly acrylamide, ENVIRA® E-221 marginally improves the dry strength and the z-axis strength. Due to its flexibility, it can be applied in either acidic or alkaline condition. Another property of ENVIRA® E-221 is its ability to improve retention and drainage capacity due to its excellent fixing abilities on fines and anionic trash.