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.

Method of preparing silicas, silicas with specific pore-size and/or particle-size distribution and the use thereof, in particular for reinforcing polymers

The invention relates to a method for preparing precipitated silica, and to precipitated silica including clusters of large primary silica particles having at the surface thereof small primary silica particles, wherein said silica has: a specific surface area CTAB (S CTAB ) of 60 to 400 m 2 /g; a cluster average size d50, as measured by XDC grading after ultrasound de-agglomeration, such that d50 (nm) > (6214 / S CTAB (m 2 /g)) + 23; a porous volume distribution such that V (d5 - d50) / V (d5 - d100) > 0.906 - (0,0013 x S CTAB (m 2 /g)); and a pore size distribution such that Mode (nm) > (4166 / S CTAB (m 2 /g)) – 9.2. The invention also relates to the use of the silica as reinforcing filler for polymers.

Novel method for preparing precipitated silica, precipitated silica having particular morphology, grading and porosity, and use thereof particularly for reinforcing polymers

The invention concerns a method for preparing low water uptake precipitated silicas, comprising successive steps which consist in: (a) producing an initial starter including a silicate, the silicate concentration in said starter, expressed in SiO2 equivalent, being less than 15 g/L; (b) bringing the medium pH to a value ranging between 7 and 8 by adding an acidifying agent, (c) in the resulting medium, simultaneously adding a silicate and an acidifying agent the respective amounts of silicate and acidifying agent added in time being specifically such that, during the entire addition (i) the reaction medium pH stays between 7 and 8, and (ii) the silicon concentration in the medium, expressed in SiO2 equivalent, stays below 35 g/L; (d) adding an acidifying agent in the medium resulting from step (c), so as to bring the medium to a pH ranging between 3 and 6.5; and (e) filtering the resulting aqueous silica dispersion, then drying the filter cake obtained at the end of the filtering step. The invention also concerns low water uptake silicas obtained by said method and their use, in particular for reinforcing silicones or polymer or elastomer matrices.

Low water uptake silicas

The invention relates to a novel silica production method comprising the reaction of a silicate with at least one acid, in which the acid used in at least one of the steps is a concentrated acid, preferably selected from the group containing sulphuric acid having a concentration of at least 80 wt.-%, in particular at least 90 wt.-%, acetic acid or formic acid having a concentration of at least 90 wt.-%, nitric acid having a concentration of at least 60-wt.%, phosphoric acid having a concentration of at least 75 wt.-%, hydrochloric acid having a concentration of at least 30 wt.-%.

Precipitated-silica production method

The present invention relates to precipitated silicas which have extremely low microporosity and high rubber activity, to a process for their preparation, and to their use as filler for rubber mixtures.

Specially precipitated silicic acids for rubber applications

The invention concerns a novel method for preparing precipitated silica used as reinforcing filler for elastomers. It also concerns novel silica precipitates in the form of powder, granules or, preferably, substantially spherical balls, said silica being characterised in that they contain: a BET specific surface area ranging between 185 and 250 m2/g; a CTAB specific surface area ranging between 180 and 240 m2/g; a porous distribution such that the porous volume V2 consisting of pores with diameter ranging between 175 and 275 A represents less than 50 % of the porous volume V1 consisting of pores with diameter not more than 400 A; a porous volume (V?d1?) consisting of pores with diameter less than 1 νm more than 1.65 cm?3?/g; a fineness number (I.F) between 70 and 100 A; a fines contents (τ?f?) after ultrasound disintegration, of at least 50 %.

Precipitated silica used as reinforcing filler for elastomers

L'invention concerne un nouveau procede de preparation de silice precipitee utilisable comme charge renforcante pour elastomeres Elle est aussi relative a de nouvelles silices precipitees sous forme de poudre, de granules ou, de preference, de billes sensiblement spheriques, ces silices etant caracterisees par le fait qu'elles possedent: une surface specifique BET comprise entre 185 et 250 m2/g, une surface specifique CTAB comprise entre 180 et 240 m2/g, une distribution poreuse telle que le volume poreux V2 constitue par les pores dont le diametre est compris entre 175 et 275 A represente moins de 50 % du volume poreux V1 constitue par les pores de diametres inferieurs ou egaux a 400 A, un volume poreux (V?d1?) constitue par les pores de diametre inferieur a 1 νm superieur a 1,65 cm?3?/g, un indice de finesse (IF) compris entre 70 et 100 A, un taux de fines (τ?f?), apres desagglomeration aux ultra-sons, d'au moins 50 %

Chevallier Yvonnick

Papers

Precipitated silica used as reinforcing filler for elastomers

Silice precipitee utilisable comme charge renforcante pour elastomeres