Abstract: Fiber-reinforced pultrusion processes have established a pivotal position in composite manufacturing due to their high efficiency and precision. Polyurethane(PU) pultrusion, characterized by rapid forming speed and minimal process odor, has emerged as an ideal matrix material for pultrusion technologies. In the PU pultrusion process, the regulation of the catalytic system is critical for production efficiency, process window, and product performance. This study systematically investigates the inhibitory effect of internal mold release agents(IMRAs) on the catalytic activity of amine- and metal-based catalysts in fiber-reinforced PU pultrusion systems. The research reveals that both acidic and alkaline IMRAs suppress catalyst activity, significantly prolonging the gel time at room temperature, whereas the inhibitory effect weakens at high temperatures. Through optimized selection of catalyst and IMRA typesand dosages—using TCAT-S054 catalyst at 0.3wt% and G-161A(4.0wt%~4.5wt%) or INT-1948(3.5wt%~4.0wt%) as IMRAs—the developed system was applied to pultrusion of photovoltaic(PV) frame profiles. The process achieved a pultrusion speed of 1.0 m/min, with the profiles exhibiting smooth surfaces and paint adhesion reaching Grade 0, meeting the highest industry standards.

Key words: pultrusion molding, polyurethane catalytic system, photovoltaic composite frame