Method of Pultrusion Employing Multiple Resins

A method of manufacturing a composite article by pultrusion comprising:

• supplying a continuous interior reinforcement layer and a continuous exterior reinforcement layer;
• infusing the interior reinforcement layer with a first resin to form an infused interior reinforcement layer;
• combining the infused interior reinforcement layer with the exterior reinforcement layer to form a pultrusion reinforcement structure;
• passing the pultrusion reinforcement structure into an infusion die and infusing the exterior reinforcement layer of the pultrusion reinforcement structure with a second resin to form an infused pultrusion reinforcement structure;
• and
• passing the infused pultrusion reinforcement structure to a curing die to cure the first and second resin in the infused pultrusion reinforcement structure to form a composite article;
• wherein the second resin comprises a polyurethane resin comprising a polyol component and an isocyanate component, and the concentration of aliphatic isocyanate in the isocyanate component is greater than the concentration of aliphatic isocyanate in the first resin.