Method of preparing silicas, silicas with specific pore-size and/or particle-size distribution, and the uses thereof, in particular for reinforcing polymers
OwnerRemi Valeroinventor
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Abstract
The invention relates to a novel method of preparing silicas and to highly-structured silicas having the following characteristics: a specific surface area CTAB (SCTAB) of between 40 and 525 m2/g; a specific surface area BET (SBET) of between 45 and 550 m2/g; an object size distribution width Ld ((d84−d16)/d50), which is measured by XDC particle size analysis after deagglomeration with ultrasound, of at least 0.91; and a pore-size distribution such that ratio V(d5−d50)/V(d5−d100) is at least 0.66. The invention also relates to the use of said silicas as polymer reinforcing fillers.
Claims50
1-51. (Canceled)
A process for preparing silica, comprising the reaction of a silicate with an acidifying agent whereby a silica suspension is obtained, followed by the separation and the drying of this suspension, said reaction of the silicate with the acidifying agent being carried out according to the following successive steps:
- (i) forming an aqueous stock having a pH of between 2 and 5;
- (ii) adding simultaneously silicate and acidifying agent to the said stock in such a way that the pH of the reaction mixture is maintained between 2 and 5;
- (iii) stopping the addition of the acidifying agent, while continuing to add silicate into the reaction mixture until a pH value of the reaction mixture of between 7 and 10, is obtained;
- (iv) adding simultaneously silicate and acidifying agent to the reaction mixture in such a way that the pH of the reaction mixture is maintained between 7 and 10;
- and
- (v) stopping the addition of the silicate, while continuing to add the acidifying agent into the reaction mixture until a pH value of the reaction mixture of less than 6 is obtained.
A silica, having:
- a CTAB specific surface area (SCTAB) of between 40 and 525 m2/g;
- a BET specific surface area (SBET) of between 45 and 550 m2/g;
- a size distribution width Ld ((d84−d16)/d50) of objects measured by XDC particle size analysis after ultrasonic disintegration of at least 0.91, and
- a pore volume distribution such that the ratio V(d5−d50)/V(d5−d100) is at least 0.66.
A silica, having:
- a CTAB specific surface area (SCTAB) of between 40 and 525 m2/g;
- a BET specific surface area (SBET) of between 45 and 550 m2/g;
- and
- a pore distribution width ldp of greater than 0.70.
A silica, having:
- a CTAB specific surface area (SCTAB) of between 40 and 525 m2/g;
- a BET specific surface area (SBET) of between 45 and 550 m2/g;
- a size distribution width L′d ((d84−d16)/d50) of objects smaller than 500 nm, measured by XDC particle size analysis after ultrasonic disintegration, of at least 0.95;
- and
- a pore volume distribution such that the ratio V(d5−d50)/V(d5−d100) is at least 0.71.
A silica, having:
- a CTAB specific surface area (SCTAB) of between 40 and 525 m2/g;
- a BET specific surface area (SBET) of between 45 and 550 m2/g;
- a size distribution width L′d ((d84−d16)/d50) of objects smaller than 500 nm, measured by XDC particle size analysis after ultrasonic disintegration, of at least 0.90;
- and
- a pore volume distribution such that the ratio V(d5−d50)/V(d5−d100) is at least 0.74.
Dependencies are inferred from the claim text.