USE OF SPECIFIC SILICAS FOR INCREASING THE RIGIDITY OF A THERMOPLASTIC WHILE MAINTAINING OR IMPROVING ITS IMPACT RESISTANCE

摘要

The invention relates to the use of a silica having a BET specific surface of at least 60 m2/g for increasing the rigidity of a thermoplastic polymeric material while maintaining i.e. improving its impact resistance. The silica used is of the type obtained according to a method involving the drying of a silica suspension obtained by reacting a silicate with an acidulant according to the following successive steps: (i) forming an aqueous starter having a pH between 2 and 5; (ii) simultaneously adding silicate and the acidulant while keeping the pH between 2 and 5; (iii) continuing with only the addition of silicate until a pH between 7 and 10 has been reached; (iv) simultaneously adding silicate and acidulant while keeping the pH of the reaction medium between 7 and 10, and; (v) continuing with only the addition of the acidulant until a pH value lower than 6 has been obtained. The invention also relates to the materials obtained within this scope.