Preparation method of composite polyurethane film

The invention discloses a preparation method of a composite polyurethane film. The preparation method comprises the following steps: (1) mixing isocyanate, polyol, and auxiliary materials together to carry out reactions so as to form a polyurethane system; (2) evenly spraying or painting the obtained polyurethane system on a separation layer; (3) laminating a substrate layer on the polyurethane system, wherein the pressing force is controlled in a range of 0 to 10 kgf/cm, and the pressing time is controlled within 30 seconds; (4) curing the polyurethane system at a low temperature to form a polyurethane layer; (5) peeling off the separation layer after cooling so as to obtain the composite polyurethane film composed of a polyurethane layer and a substrate layer finally. The preparation method has the advantages of simple operation, low cost, and high production efficiency. The prepared film has the advantages of diverse and decorative surface, and user-friendliness. Moreover, the polyurethane layer is not easy to separate, and the adhesion is firm.