Auxiliary agent used for PVC processing and preparation method thereof

The invention discloses an auxiliary agent used for PVC processing and a preparation method thereof. The auxiliary agent used for PVC processing has a core-shell structure with a calcium maleate-styrene copolymer as a core and alkyl methacrylate as a shell, and has an intrinsic viscosity of 3.0 to 10.0. The preparation method for the auxiliary agent used for PVC processing comprises the following steps: (1) adding distilled water, a calcium maleate monomer, an initiator A, an emulsifier, a dispersant and a styrene monomer into a reactor, and carrying out stirring so as to obtain a pre-emulsion; (2) introducing N2, carrying out heating to 40 to 90 DEG C, and carrying out a heat-preserving reaction under continuous stirring for 0.5 to 5 hours so as to obtain a core-shell emulsion; and (3) adding an initiator B and an alkyl methacrylate monomer into the core-shell emulsion, carrying out heating to 50 to 95 DEG C, carrying out a reaction under stirring at a constant temperature for 1 to 5 hours, carrying out cool