Process for making a flameproof coating for electric cables

摘要

Process for making a flameproof compound comprising a preliminary step wherein a nanoclay obtained starting from a smectitic clay is dispersed in a polymeric matrix in order to obtain a nanocomposite. The nanocomposite is then added to a inorganic flame retardant compound to obtain a flameproof product with improved characteristics with respect to similar products of prior art. This result is obtained undergoing the nanoclay to a purification process suitable for reducing the content of impurities less than 1% by weight. The purification process provides a primary separation of the impurities from an aqueous dispersion by a vibro-sieve for removing macroscopic impurities such as sand (12); then a secondary separation is provided of the impurities from the aqueous dispersion at the outlet of the vibro-sieve by a hydrocyclone, for removing the impurities up to reducing its content at about 9% (13). Then the aqueous dispersion is caused to decant at the outlet of the hydrocyclone up a content by weight of the impurities less than 4% by weight, through the removal of heavy particles of quartz and feldspar (14). Then a centrifugation at a high speed is provided of the decanted aqueous dispersion up to reaching a highly purified nanoclay with a content of impurities less than 1% by weight, owing to the removal of light particles of quartz and cristobalite, block (15).