Description of the production of cast polyurethane rubber seals

(1) Composition of cast type polyurethane elastomer prepolymer
1 Dehydration The molten material is heated to 100~120 °C, and it is taken off for 2 hours under full mixing, then placed in a vacuum drying box and heated to 110 ° C, and the vacuum is 0.09 MPa for 2 hours. This can make the water in the quality guess from 0.1. % drops to 0.03% and reaches the demand for the composition of the prepolymer.

The sealing member is prepared by heating the prepolymer to 100 ° C and evacuating (vacuum degree 0.095 MPa) to degas; weighing the crosslinking product MOCA, heating and melting in an electric furnace; preheating the mold 120 to C), and Apply a suitable release product; degassed prepolymer and melted. MOCA is mixed at 100 ° C and mixed evenly; the mixture is mixed evenly and carefully poured into the mold. When the mixture is inactive or the surface is not sticky (gel-like), the mold is closed and placed in the flat vulcanizing machine. Molded vulcanization at 120~130°C; the vulcanization time of large and thick seals is 30min, and the small and thin seals are 20min; the molded products are placed in a 100~C. oven for continuous vulcanization (post vulcanization) 10h, then placed at room temperature for 10d.