Silica-Base rubber composition intended for the manufacture of highway tires improved resistance to rolling
AssigneeCompagnie Generale des Establissements Michelin-Michelin & Cie
InventorsJean-Marie Micouin, Yvonick Chevallier
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Abstract
The present invention relates to a rubber composition intended for the manufacture of road tires of improved resistance to rolling having a base of precipitated silica with a relatively high specific surface and special porosity properties.
Claims27
A sulfur-vulcanizable rubber composition intended for the manufacture of road tires which have a reduced resistance to rolling, having a base of at least one diene polymer, characterized by the fact that it contains as reinforcing filler a highly dispersible silica obtained by precipitation in the following manner:
- (i) an initial reaction vessel bottoms is formed comprising at least a part of the total amount of silicate engaged in the reaction and at least one electrolyte, the concentration in silicate (expressed in SiO2) in said initial reaction vessel bottoms between 50 and 60 g/l,
- (ii) the acidifying agent is added to the said reaction vessel bottoms until obtaining a pH of the reaction medium of between 7 and 8.5,
- (iii) acidifying agent is added to the reaction medium and, possibly, at the same time the remaining amount of the silicate.
- the separation comprises a filtration and a washing by means of a filter equipped with a compacting means,
- a suspension having a rate of dry matter of less than 17% by weight is dried by atomization,
- and by the fact that said silica is subjected in a first step to a thermo-mechanical working with the diene elastomer to constitute a mixture which is then subjected with at least one coupling agent in a second stage to two steps of thermo-mechanical working.
A sulfur-vulcanizable rubber composition intended for the manufacture of road tires, having a base of at least one diene polymer, characterized by the fact that as reinforcing filler it contains a silica having:
- a BET specific surface of between 185 and 250 m2/g,
- a CTAB specific surface of between 180 and 240 m2/g,
- a pore distribution such that the pore volume V2 formed by the pores the diameter of which is between 175 and 275 Å represents less than 50% of the pre volume V1 formed by pores of a diameter less than or equal to 400 Å,
- a pore volume (Vd1) formed by pores of a diameter less than 1 μm, greater than 1.65 cm3/g,
- a fineness index (F.I.) of between 70 and 100 Å,
- a fines ratio (τf) after deagglomeration by ultrasonics of at least 50%.
A method of improving the properties of resistance to rolling of sulfur-vulcanizable diene rubber compositions and intended for the manufacture of road tires comprising silica as reinforcing filler, characterized by the fact that it consists of reinforcing compositions with a precipitated silica having:
- a BET specific surface of between 185 and 250 m2/g,
- a CTAB specific surface of between 180 and 240 m2/g,
- a pore distribution such that the volume V2 formed by pores the diameter of which is between 175 and 275 Å represents less than 50% of the pore volume V1 formed by the pores of diameter less than or equal to 400 Å,
- a pore volume (Vd1) formed by pores of a diameter less than 1 μm, greater than 1.65 cm3/g,
- a fineness index (F.I.) of between 70 and 100 Å,
- a fines ratio (τf) after deagglomeration by ultrasonics, of at least 50%,
- subjecting said silica in a first stage to thermo-mechanical working with the diene elastomer and that in a second stage subjecting the mixture obtained at the outlet of the first stage with at least one coupling agent to two thermo-mechanical working steps.
A road tire having a reduced resistance to rolling comprising a diene rubber composition which is sulfur-vulcanizable, comprising silica as reinforcing filler, characterized by the fact that the composition comprises a highly dispersible precipitated silica having:
- a BET specific surface of between 185 and 250 m2/g,
- a CTAB specific surface of between 180 and 240 m2/g,
- a pore distribution such that the pore volume V2 formed by pores the diameter of which is between 175 and 275 Årepresents less that 50% of the pore volume V1 formed by the pores of diameter less than or equal to 400 Å,
- a pore volume (Vd1) formed by pores of a diameter less than 1 μm, greater than 1.65 cm3/g,
- a fineness index (F.I.) of between 70 and 100 Å,
- a fines ratio (τf) after deagglomeration by ultrasonics, of at least 50%.
A tread for road tires having a base of a composition of sulfur-vulcanizable diene rubber comprising silica as reinforcing filler, characterized by the fact that the composition comprises a highly dispersible precipitated silica having:
- a BET specific surface of between 185 and 250 m2/g,
- a CTAB specific surface of between 180 and 240 m2/g,
- a pore distribution such that the pore volume V2 formed by pores the diameter of which is between 175 and 275 Å represents less than 50% of the pore volume V1 formed by pores of a diameter less than or equal to 400 Å,
- a pore volume (Vd1) formed by pores of a diameter less than 1 μm, greater than 1.65 cm3/g,
- a fineness index (F.I.) of between 70 and 100 Å,
- a fines ration (τf), after deagglomeration by ultrasonics, of at least 50%.
Dependencies are inferred from the claim text.