Wet end chemicals for dry end strength in paper

摘要

The invention provides methods and compositions for increasing the dry strength of paper. The invention utilizes a tailored strength agent whose size and shape is tailored to fit into the junction points between flocs of a paper sheet. The strength agents is in contact with the slurry for just enough time to collect at the junction points but not so much that it can migrate away from there.

主权项

1. A method of increasing the strength of a paper substrate, the method comprising in order:
adding a cationic wet strength agent to a paper substrate, adding a flocculating agent to the paper substrate, and adding a glyoxalated polyacrylamide (GPAM) copolymer to the paper substrate, wherein addition of GPAM occurs in the wet-end of a papermaking process after the substrate has passed through a screen but no more than 18 seconds before the substrate enters a headbox.