FIELD: paper production.
SUBSTANCE: application of strengthening additives using foam technologies on wet formed paper canvas. Foam composition is presented for obtaining foam with a given gas content by introducing gas into a foam composition intended for application to wet, newly formed paper webs, which includes at least one blowing agent in an amount of from about 0.001% to about 10% by weight based on the total weight of the foam composition, selected from a non-ionic or zwitterionic or amphoteric or cationic blowing agent; at least one synthetic hardening additive in an amount of about 0.01% to about 50% by weight based on the total weight of the foam composition, and at least one synthetic hardening additive includes a cationic functional group and is a nitrogen-containing cationic polymer; water. In another embodiment, a similar foam composition is provided in which the concentration of at least one blowing agent in the foam composition is substantially the minimum sufficient to provide a given foam gas content after the gas has been incorporated into the foam composition. Also provided is a method for incorporating a synthetic cationic strength additive into a paper product, comprising making a foam from the foam formulation described above and applying the foam to a wet, freshly formed canvas.
EFFECT: group of inventions provides improvements in bond-mediated strength characteristics of paper, such as dry tensile strength.
9 cl, 20 dwg, 18 tbl, 18 ex
