PROCEDIMIENTO DE AGLOMERADO DE ARIDOS CON CATALIZADOR ACTI- VADO MEDIANTE VACIO

摘要

In the manufacture of cores and molds, an aggregate such as silica is mixed with a polymerizable binder such as a phenolic resin and with an organic or inorganic acid catalyst which has been blocked by reversible reaction with a volatile base e.g. an amine. The resultant mixture is heated under a reduced pressure of 10 to 70 mm Hg to unblock the catralyst and thereby effect polymerization of the binder. The use of high temperatures and unpleasent gaseous catalysts is avoided.