Elastomeric composition having a very good dispersion of the filler in the elastomeric matrix

Abstract

The invention relates to a rubber composition based on at least one diene elastomer, a reinforcing filler comprising at least carbon black having a CTAB specific surface of greater than or equal to 130 m 2 /g, a plasticizing oil and also a crosslinking system, the dispersion of the filler in the elastomeric matrix having a Z score of greater than or equal to 70.

1 . A process for the preparation of a composition comprising at least one diene elastomer, a reinforcing filler comprising at least carbon black having a CTAB specific surface of greater than or equal to 130 m 2 /g, a plasticizing oil and also a crosslinking system, which comprises the following stages:
 preparing a first masterbatch comprising the diene elastomer and the carbon black, this first masterbatch exhibiting a dispersion of the filler in the elastomeric matrix having a Z score of greater than or equal to 80,   incorporating the other constituents of the composition, with the exception of the crosslinking system, in the first masterbatch in a mixer, and kneading everything thermomechanically until a maximum temperature of between 130° C. and 200° C. is reached,   cooling the combined mixture to a temperature of less than 100° C.,   subsequently incorporating the crosslinking system,   kneading everything up to a maximum temperature of less than 120° C.   
     
     
         2 . The process according to  claim 1 , wherein the first masterbatch is produced in the liquid phase from at least one elastomer latex and a dispersion of carbon black. 
     
     
         3 . The process according to  claim 2 , wherein the first masterbatch is produced according to the following successive stages:
 feeding a continuous stream of the diene elastomer in the form of a latex to a mixing region of a coagulation reactor defining an elongated coagulation region extending between the mixing region and an outlet orifice,   feeding a continuous stream of a fluid comprising the filler under pressure to the mixing region of a coagulation reactor in order to form a coagulated mixture,   drying the coagulum obtained above in order to recover the first masterbatch.   
     
     
         4 . The process according to  claim 1 , wherein the plasticizing oil is selected from the group consisting of a polyolefinic oil, a paraffinic oil, a naphthenic oil, an aromatic oil, a mineral oil, or mixtures thereof. 
     
     
         5 . The process according to  claim 4 , wherein the plasticizing oil includes a polyolefinic oil and/or a paraffinic oil. 
     
     
         6 . The process according to  claim 4 , wherein the plasticizing oil includes a naphthenic oil, an aromatic oil, a mineral oil, and/or mixtures thereof. 
     
     
         7 . The process according to  claim 1 , wherein the content of the plasticizing oil varies from 2 to 50 parts per hundred parts by weight of elastomer. 
     
     
         8 . The process according to  claim 1 , wherein the diene elastomer is selected from the group consisting of polybutadienes, natural rubber, synthetic polyisoprenes, butadiene copolymers, isoprene copolymers, and the mixtures of these elastomers. 
     
     
         9 . The process according to  claim 8 , wherein the at least one diene elastomer includes a natural rubber. 
     
     
         10 . The process according to  claim 4 , wherein the plasticizing oil includes a mineral oil or a mixture of mineral oils. 
     
     
         11 . The process according to  claim 8 , wherein the diene elastomer includes a blend of one or more natural rubber latexes with one or more synthetic rubber latexes. 
     
     
         12 . The process according to  claim 1 , wherein the content of the carbon black varies from 20 to 80 phr. 
     
     
         13 . The process according to  claim 1  further comprising introducing an inorganic filler, or a second elastomer, or both into the composition simultaneously with the other constituents during the kneading step. 
     
     
         14 . The process according to  claim 13 , wherein the second elastomer is identical to or different from the at least one diene elastomer. 
     
     
         15 . The process according to  claim 13 , wherein an inorganic filler and a second elastomer are introduced into the composition in the form of a second masterbatch. 
     
     
         16 . The process according to  claim 15 , wherein the second masterbatch is prepared prior to its incorporation into the kneading step. 
     
     
         17 . The process according to  claim 13 , wherein the content of the inorganic filler varies from 5 to 50 phr. 
     
     
         18 . The process according to  claim 1 , wherein an inorganic filler and a second elastomer are introduced separately into the composition, the inorganic filler being introduced before or after the second elastomer. 
     
     
         19 . The process according to  claim 18 , wherein the introduction of the inorganic filler and of the second elastomer is offset in time from a few tens of seconds to a few minutes with respect to the introduction of the first masterbatch into the mixer. 
     
     
         20 . The process according to  claim 1 , wherein the content of all of the reinforcing filler varies from 20 to 200 phr.