Manufacturers have used the pultrusion process for manufacturing composite products for decades. The resin in pultrusion process traditionally can be divided into polyester, vinyl ester and epoxy resin. The use of polyurethane resin pultrusion is a newly developed technology, Germany Bayer Material Sciences Corp is vigorously promoting the development of this technology, and has contributed to the number of polyurethane pultruded products successfully listed.
A new type of two-component polyurethane pultrusion is using a patented method to polyol and a highly reactive isocyanate mixture formation. Isocyanate is optimized for pultrusion characteristics of choice, its characteristics are low viscosity (to ensure good impregnated fiber), gel time is long (easy to start and stop), polymerization (rapidly improve the forming speed), good surface finish and cost-competitive. Compared with other materials, polyurethane pultrusion can produce many kinds of benefits. It can increase the glass fiber content in the product and make the product strength greatly improved. For example, pultrusion window frames made of glass fiber and polyurethane resin, the strength is eight times higher than the PVC window, its electrical conductivity is 40 times lower than aluminum, so the insulation performance much better. At the same time, because of the smaller brittleness of polyurethane pultruded window frames, they won’t crack and durable.