PROCESSO DE PREPARAÇÃO DE SÍLICAS, SÍLICAS COM DISTRIBUIÇÃO GRANULOMÉTRICA E/OU REPARTIÇÃO POROSA ESPECÍFICAS E SUAS UTILIZAÇÕES, EM PARTICULAR NO REFORÇO DE POLÍMEROS
Controlled addition of an acidifying agent to a silicate in stages to form a silica suspension which, after washing and drying, has specified characteristics. Preparation of silica by the reaction of an acidifying agent with a silicate, effected in the following stages: (1) Formation of an aqueous base material of pH 2 -5 (preferably 2.5 - 5)； (2) Simultaneous addition of a silicate and acidifying agent such that the pH is maintained at 2 - 5 (preferably 2.5 - 5)； (3) Cease addition of acidifying agent whilst continuing addition of silicate until pH is 7 - 10 (preferably 7.5 - 9.5)； (4) Resume simultaneous addition of agent and silicate to maintain pH at 7.5 - 9.5； and (5) Cease addition of silicate whilst continuing addition of acid until a pH value less than 6 is attained. Independent claims are also included for the silica obtained and its uses.
