Patent ID: 7678232

Claim:
A method of making a paper sheet comprising: (a) forming an aqueous suspension of papermaking fibers; (b) adding to the aqueous suspension, prior to web formation, a water soluble or water dispersible aldehyde functional ionic polymer followed by the addition of a paper modifying agent having a non-hydroxyl aldehyde reactive functional group, which react according to the following reaction: (c) filtering and washing the papermaking fibers containing the aldehyde functional ionic polymer reacted with derivatized paper modifying agent; (d) depositing the aqueous suspension of papermaking fibers onto a forming fabric to form a web; and (e) dewatering and drying the web to form a paper sheet, wherein: b, c, f>0; a, e≧0; e+f=b; w≧1; Q 1 =a monomer unit or a block or graft copolymer prepared from the polymerization of one or more ethylenically unsaturated compounds, said monomer unit or block or graft copolymer containing a pendant group capable of forming hydrogen bonds with cellulose; R 1 , R 1′ , R 1″ =independently H or C 1-4 alkyl; R 2 =any linear or branched, aliphatic or aromatic, saturated or unsaturated, substituted or unsubstituted hydrocarbon group containing a pendant aldehyde functionality; R 3 =an aliphatic hydrocarbon, an amphiphilic hydrocarbon, humectant or other agent capable of modifying the paper sheet; Z 1 =a reactive group capable of reacting with an aldehyde in an aqueous environment to form a covalent bond which is stable in the aqueous environment; Z 2 =the covalently bonded bridging radical formed by the reaction of the aldehyde functionality with Z 1 functional moiety; and Q 3 =a monomer unit or a block or graft copolymer, said monomer unit or block or graft copolymer containing a charge functionality wherein the charge functionality is selected from the group consisting of cationic, anionic and amphoteric.