Pultruded plank, spar cap, wind turbine blade, and pultrusion preparation process

A pultrusion preparation process for making a pultruded plank for a spar cap of a wind turbine blade, wherein at least two pultruded planks form the spar cap by stacking and a laminated infusion process, comprising:

• a step of forming a core in which a pultruded core of the pultruded plank is formed by dragging reinforced fibers impregnated with a core resin through a pultrusion die for heating and solidifying;
• a step of forming an interface layer in which an interface resin is coated on at least one surface of the pultruded core through a glue injection mold process, and the interface layer is defined to have a predetermined thickness when not gelled, wherein the interface layer allows the pultruded plank to be wound and packaged after hardening, and defines a bonded surface of the pultruded plank, the interface resin containing an isocyanate resin and a polyester resin, and a mass ratio of the isocyanate resin to the polyester resin being 1:3~2:3;
• a winding step in which the pultruded plank is wound and packaged after the interface layer is hardened.