Preparation method of graft polymer and graft polymer

The invention relates to the technical field of emulsion graft polymerization, and discloses a preparation method of a graft polymer and the graft polymer. The preparation method comprises the following steps: (1) in the presence of a first initiator, contacting a seed polymer emulsion, a molecular weight regulator, a first activator and a first grafting monomer to carry out graft polymerization reaction; (2) after the reaction in the step (1) is finished, supplementing a second activating agent, a second grafting monomer and a second initiator to carry out a first incremental reaction; (3) selectively supplementing a third activating agent in the step (2) to carry out a second incremental reaction; after the second grafting monomer is supplemented, supplementing a third initiator to carry out a third incremental reaction to obtain grafted latex; and (4) carrying out condensation, curing and dehydration treatment on the grafted latex to obtain the grafted polymer. According to the method, different amounts of