Centrifugal casting of glass fiber-reinforced pipes, takes place in rotary molds in succession, heated externally by water to assure rapid setting of selected catalyst-resin system for maximum production rate without fissuring

摘要

The mold is at 40 deg C-75 deg C during raw material introduction. Its thermal capacity is sufficiently high that its temperature is reduced by no more than 10 deg C by the raw materials. Hot water is used to heat it. Independent claims are is included for the centrifugal casting plant and pipes made using the method described. Preferred features: Following initiation of exothermic reaction, hot water is sprayed on the mold, maintaining a temperature of at least 60 deg C, until the tube is extracted. Resin setting time in outer layers, is the same as, or greater than that in the inner layers. Filler content is 40% or more. Water temperature is 60 deg C. The tube is a multilayer. Excepting innermost and outermost layers, resin reactivity is greater towards the innermost layer. Just before extraction, hot water is sprayed onto the mold, which is brought to the temperature required for the next molding. Mold temperature remains at 70 deg C at least, until the tube is pulled out. Accelerator or inhibitor are added judiciously ahead of the lance to control reactivity. Reactivity is raised in the sand layers in the center of the pipe. Two catalyst pumps are provided for different catalysts, for mixtures with differing polymerization initiation temperatures; use of material with higher initiation temperature, delays setting. There are more, longer glass fibers on the inner side of the tube than there are shorter fibers on the outer side. In the outer layers where there is no sand; there are some short and some long glass fibers. Further details of construction, fiber orientation and compositions are provided.