Polyurethane surface layer resin for PVC sole injection molding and preparation method thereof

The invention relates to a polyurethane surface layer resin for PVC sole injection molding and a preparation method thereof. The surface layer resin is composed of the following components in percentage by weight: 5-12% of diisocyanate, 18-25% of polyester polyol, 0.5-1.5% of a chain extender, and the balance of a solvent. The preparation method comprises the following steps of A, adding polyesterpolyol and a solvent accounting for 25-40% of the total weight of the components into a reaction container, stirring at 50-60 DEG C for 20-30 minutes, adding aliphatic diisocyanate, heating to 100-110 DEG C, and continuing to stir to react for 100-120 minutes, and B, adding the residual solvent and chain extender, stirring for 30 minutes, adding aromatic diisocyanate, controlling the temperatureto be 70-80 DEG C, controlling the viscosity of reactants to be 100-160 Pa.s/25 DEG C, and cooling to obtain the polyurethane surface layer resin for PVC sole injection molding. Under the condition that no adhesive is used, th