Rhodia Operations

Compagnie Generale Des Etablissements Michelin

Rhodia Chimie

Sylvaine Neveu

Laurent Guy

Emmanuelle Allain Najman

Pascaline Garbey

Anne-Laure Pinault

Caroline Fayolle

Emmanuelle Allain

Joël Racinoux

Malika Clouin

Cédric Feral-Martin

Daniel Joubert

Eric Perin

Cédric Boivin

Sophie Vaslin

Fabien Stocklouser

Elise Fournier

Philippe Jost

Stéphane Badaire

Angélique Pawlak

A precipitated silica containing are least one element M selected from the group consisting of B, Al, Ga and mixtures thereof and characterized by the presence of specific acid sites on its surface and a process for its manufacture. Said precipitated silica is suitable for multiple applications, for instance as catalyst or catalyst support as well as reinforcing filler in polymeric compositions.

Precipitated silica and process for its manufacture

A precipitated silica having a broad particle size distribution and large median particle size as well as its method of manufacture is provided. The precipitated silica has a CTAB surface area Sin the range from 40 to 300 m/g, a difference between BET surface area Sand CTAB surface area Sof at least 35 m/g, a width of the particle size distribution Ld, measured by centrifugal sedimentation, of at least 1.5, an amount of aluminium Win the range from 0.5 to 7.0 wt %, and a median particle size d50, measured by centrifugal sedimentation, such that for a given value of CTAB surface area Sand amount of aluminium W, parameter A, defined by the following equation: A=|d50|+0.782×|S|−8.524×|W|.

A precipitated silica characterised by the presence of specific acid sites on its surface and a process for its manufacture.

A rubber composition is based on at least one elastomer, a reinforcing inorganic filler, an agent for coupling the elastomer to the reinforcing inorganic filler, and a crosslinking system. The reinforcing inorganic filler comprises at least one silica S having: a CTAB specific surface area Swithin a range extending from 40 to 300 m/g; a difference between the BET specific surface area Sand the CTAB specific surface area Sof greater than or equal to 35 m/g; an aluminium content Wwithin a range extending from 0.5 to 7.0% by weight relative to the weight of the silica S; a width of the aggregate size distribution Ld, measured by centrifugal sedimentation, of greater than or equal to 1.5; and a median aggregate diameter d50, measured by centrifugal sedimentation, such that for a given value of CTAB specific surface area Sand a given aluminium content W, a magnitude A is defined by the following equation (I): A=[d50]+0.782&#xd7;[S]&#x2212;8.524&#xd7;[W] (I), in which: [d50] is the numerical value of d50, expressed in nm; [S] is the numerical value of S, expressed in m/g; [W] is the numerical value of W, expressed in % by weight relative to the weight of the silica S; and said magnitude A satisfies the relationship (II): A&#x2265;253 (II). The compositions of the invention are of use in tyres or semi-finished articles for tyres.

Rubber composition comprising at least one silica as inorganic reinforcing filler

A process for preparing precipitated silica comprising a reaction of a silicate with an acidifying agent to obtain a suspension of precipitated silica, followed by a step of separation to obtain a cake and a step of drying said cake, wherein a step of compaction of said cake at a pressure greater than 10 bars is carried out between the step of separation and the step of drying.

Process for preparing precipitated silica comprising a high compaction step

A precipitated silica having a CTAB specific surface in the range of from 50 to 300 m/g; a BET/CTAB specific surface ratio equal to or greater than 1.3 and comprising at least one polycarboxylic acid.

Process for the preparation of precipitated silicas, precipitated silicas and their uses, in particular for the reinforcement of polymers

A process for preparing precipitated silica comprising a reaction of a silicate with an acidifying agent to obtain a suspension of precipitated silica (S1), followed by a separation step to obtain a cake, a disintegration step of said cake to obtain a suspension of precipitated silica (S2), and a drying step of this suspension, wherein the disintegration step is performed by mixing using a twin-screw mixer or by extrusion.

Process for preparing precipitated silica using a mixer or extruder

A process for preparing precipitated silica in which: (i) an aqueous stock having a concentration of alkali metal silicate less than 20 g/L is formed; (ii) acid is added to said initial stock, until at least 50% of the amount of MO is neutralized; (iii) silicate and acid are simultaneously added, such that the degree of consolidation is greater than 4 and at most 100; (iv) silicate and acid are simultaneously added, such that the pH of the reaction medium is between 7 and 10; (v) acid is added until a pH value of between 2.5 and 5.3 is obtained; and (vi) the reaction medium is placed in contact with acid and silicate, such that the pH is between 2.5 and 5.3, wherein the acid used in at least one of the process steps is a concentrated acid.

Process for preparing precipitated silica

A precipitated silica production process that includes a precipitation reaction between a silicate and an acid is described, in which the acid used in at least one of the steps of the process is a concentrated acid.

Precipitated silica production process

A process for preparing precipitated silica comprising a precipitation reaction between silicate and an acid, in which the acid used in at least one of the steps is a concentrated acid, preferably selected from the group consisting of sulfuric acid having a concentration of at least 80% by weight, in particular at least 90% by weight, acetic acid having a concentration of at least 90% by weight, formic acid having a concentration of at least 90% by weight, nitric acid having a concentration of at least 60% by weight, phosphoric acid having a concentration of at least 75% by weight, and hydrochloric acid having a concentration of at least 30% by weight.

Process for preparing precipitated silicas

A process for preparing precipitated silicas in which: (i) an aqueous stock with a pH of between 2 and 5 is formed; (ii) silicate and acid are simultaneously added to said stock, such that the pH of the resulting reaction medium is maintained between 2 and 5; (iii) silicate is added until a pH value of between 7 and 10 is obtained; (iv) silicate and acid are simultaneously added, such that the pH of the reaction medium is between 7 and 10; (v) acid is added until a pH value of between 2.5 and 5.3 is obtained; and (vi) the reaction medium is placed in contact with acid and silicate, such that the pH is between 2.5 and 5.3; wherein the acid used in at least one of the process steps is a concentrated acid.

The invention relates to a process for the preparation of precipitated silica formed of aggregates of large primary silica particles, at the surface of which occur small primary silica particles, in which the acid used in at least one of the process steps is a concentrated acid.

Process for preparing precipitated silica having specific morphology, particle size and porosity

A silica production method comprising reacting a silicate with at least one acid, in which the acid used in at least one of the steps of the production method is a concentrated acid, preferably selected from the group consisting of sulfuric acid having a concentration of at least 80% by weight, in particular at least 90% by weight, acetic acid having a concentration of at least 90% by weight, formic acid having a concentration of at least 90% by weight, nitric acid having a concentration of at least 60% by weight, phosphoric acid having a concentration of at least 75% by weight, and hydrochloric acid having a concentration of at least 30% by weight.

A process for preparing precipitated silica comprising a reaction of a silicate with an acidifying agent to obtain a suspension of precipitated silica (S1), followed by a step of separation to obtain a cake, a step of spalling said cake to obtain a suspension of precipitated silica (S2) and a step of drying said suspension, wherein the spalling step is carried out at a temperature of between 50 and 120&#xb0; C.

Process for preparing precipitated silica comprising a step of high temperature spalling

A process for preparing precipitated silica, in which a silicate is reacted with an acidifying agent in order to obtain a suspension of precipitated silica (S), followed by: a separation step in order to obtain a cake, a cake-disintegration step in order to obtain a suspension of precipitated silica (S), and a suspension drying step. According to the invention, a membrane concentration step is performed between the disintegration step and the drying step.

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Paris, France

Sylvaine Neveu