Patent ID: 7786238

Claim:
Cationic starch graft polymer composed of the monomers a) to d) a) 20- 80% by weight of acrylamide, methacrylamide or mixtures thereof, b) 3- 20% by weight of at least one basic or cationic vinyl monomer, c) 0.005- 1.5% by weight of at least one bifunctional or higher-functional crosslinking agent, d) 0- 10% by weight of at least one nonionic or anionic vinyl monomer which differs from the monomers mentioned under a) to c) and a grafting base e) e) 15- 70% by weight of at least one starch whose molecular weight has been reduced by partial degradation, the sum of a) to e) being 100% by weight; wherein the cationic starch graft polymer can form a 5 to 25 percent by weight solution in water at 23° C.; and wherein the cationic starch graft polymer is a product of a process comprising a first step comprising free radical polymerization of grafting base e) in water with at least 30% by weight of the total amount of component b) to form a reaction mixture, and a second step comprising free radical polymerization of components a), c), d), and any remaining amount of component b) in the presence of the reaction mixture.