New products having excellent sizing action, in particular on paper are obtained by reacting .alpha.,.beta.-unsaturated carboxylic acids or their reactive derivatives (such as, for example, esters or anhydrides) with amide-amines of higher carboxylic acids at temperatures above 120.degree. C. The new products are used in size formulations, preferably as aqueous alkaline and, in particular, aqueous ammoniacal, dispersions.
The present invention uses hydrophobically modified polyaminamide with standard wet strength agent to produce a softer and more absorbent paper material. The hydrophobically modified polyaminamide is substantive to cellulosic fibers, thus is able to carry polyethylene glycol esters or ethers, a non-substantive material to cellulosic fiber as stable complexes, into the paper product.
