Rhodia Operations

Compagnie Generale Des Etablissements Michelin

Michelin Recherche Et Technique S.a.

Emmanuelle Allain

Sylvaine Neveu

Laurent Guy

Julien Hernandez

Dominique Dupuis

Damien Thomasson

Lionel Ventelon

Marc Airiau

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 process for preparing precipitated silica in which: (i) an stock having a concentration of alkali metal M 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; and (v) acid is added until a pH value of between 2.5 and 5.3 is obtained, wherein the acid used in at least one of the process steps is a concentrated acid.

The invention concerns the combined use, in an elastomer composition preferably comprising an isoprene elastomer, a precipitated silica containing titanium and a specific conjugated diene compound, such as a conjugated diene phosphonate or phosphinate compound. It also concerns the elastomer compositions obtained and the items produced from said compositions.

Use of a precipitated silica containing titanium and a specific coupling agent in an elastomer composition

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

The invention relates to a method for preparing precipitated silica, consisting in: (i) forming a starter having a pH of between 2 and 5; (ii) simultaneously adding silicate and acid, such that the pH of the reaction medium is between 2 and 5; (iii) adding silicate until the pH is between 7 and 10; (iv) simultaneously adding silicate and acid, such that the pH is between 7 and 10; (v) adding acid until the pH is between 2.5 and 5.3; (vi) bringing the reaction medium into contact with the acid and the silicate, such that the pH is between 2.5 and 5.3; and (vii) adding silicate, such as to increase the pH to a value between 4.7 and 6.3.

Method for preparing precipitated silica

Precipitated silicas including clusters of large primary silica particles having at the surface thereof small primary silica particles, have a specific surface area CTAB (S) ranging from 60 to 400 m/g; a cluster average size d50, as measured by XDC grading after ultrasound deagglomeration, such that d50 (nm)&#x3e;(6214/S(m/g)+23; a pore volume distribution such that V/V&#x3e;0.906&#x2212;(0.0013&#xd7;S(m/g)); and a pore size distribution such that Mode (nm)&#x3e;(4166/S(m/g))&#x2212;9.2; such silicas are useful reinforcing fillers for polymers.

Precipitated silica having particular morphology, grading and porosity, preparation thereof and reinforcing of polymers therewith

A diene rubber composition for tires based on at least (i) one diene elastomer, (ii) one reinforcing inorganic filler and (iii) one coupling agent which provides the bonding between the inorganic filler and the elastomer. The inorganic filler comprises at least one silica capable of being obtained by the preparation process of the type 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. The reaction of the silicate with the acidifying agent is carried out according to the following successive stages: (i) an aqueous suspension of precipitated silica, exhibiting a pH of between 2.5 and 5.3, is brought into contact (mixing) with acidifying agent and silicate, in such a way that the pH of the reaction medium is maintained between 2.5 and 5.3, (ii) silicate is added to the reaction medium obtained, so as to increase the pH of the reaction medium up to a value of between 4.7 and 6.3.

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L'Hay les Roses, France

Emmanuelle Allain