Patent ID: 8278374

Claim:
A process for manufacture of a dry strength paper, comprising: applying to a paper or a paper pulp at least one cationic starch graft polymer and a grafting base; wherein the at least one cationic starch graft polymer is composed of monomers a) to d): a) 20-80% by weight of an acrylamide, a 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); wherein the grafting base is composed of grafting base e): e) 15-70% by weight of at least one starch or starch derivative, and wherein the sum of a) to e) is 100% by weight; and wherein the cationic starch graft polymer is prepared by a process comprising: free radical polymerization in water of the grafting base e) and at least 30% by weight of the total amount of monomer b) to form a reaction mixture; and free radical polymerization of monomers a), c), d) and the remaining amount of b) in the presence of the reaction mixture to form the cationic starch graft polymer.