Process for incorporating poorly substantive paper modifying agents into a paper sheet via wet end addition

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;
• Q1=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;
• R1, R1′, R1″=independently H or C1-4 alkyl;
• R2=any linear or branched, aliphatic or aromatic, saturated or unsaturated, substituted or unsubstituted hydrocarbon group containing a pendant aldehyde functionality;
• R3=an aliphatic hydrocarbon, an amphiphilic hydrocarbon, humectant or other agent capable of modifying the paper sheet;
• Z1=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;
• Z2=the covalently bonded bridging radical formed by the reaction of the aldehyde functionality with Z1 functional moiety;
• and
• Q3=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.