Carcass reinforcement for tire intended to bear heavy loads

Abstract

A carcass reinforcement for a tire which is intended to bear heavy loads, comprising a composite fabric which comprises a rubber composition of reduced hysteresis and metal cables reinforcing the composition. The elastomeric matrix thereof comprises natural rubber or a synthetic polyisoprene in a majority proportion, and a reinforcing filler comprising a carbon black which meets all of the following conditions: (i) 45≦CTAB specific surface area in m2 / g (in accordance with Standard ASTM D3765-80)≦70, (ii) 45≦BET specific surface area in m2 / g (in accordance with Standard ASTM D4820-93)≦70, (iii) 45≦iodine adsorption index IA in mg / g (in accordance with Standard ASTM D1510-81)≦70, (iv) ratio (BET surface area / index IA)≦1.07, (v) 115≦DBP structure value in ml / 100 g (in accordance with Standard ASTM D2414-93)≦170, (vi) 85 nm≦Stokes diameter dst in nm≦145, where dst is the diameter of aggregates corresponding to the maximum frequency of the Stokes diameters in a distribution of aggregates, and (vii) D50 / dst≧0.0090. CTAB+0.19, where D50 is the difference, in the distribution of aggregates, between the Stokes diameters of two aggregates corresponding to one and the same frequency equal to 50% of the maximum frequency of the Stokes diameters, dst and D50 being measured by centrifugal photosedimentometry.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] The present application is a continuation of PCT Application No. PCT / EP2003 / 010521, filed Sep. 22, 2003, published in French on Apr. 15, 2004, as WO 2004 / 030946, which claims priority of French Application No. 02 / 12213, filed Oct. 2, 2002, the entire contents of both applications being incorporated herein in their entirety.FIELD OF THE INVENTION [0002] The present invention relates to a carcass reinforcement for a tire which is intended to bear heavy loads, such as a heavy-vehicle or construction-machinery tire, and to such a heavy-vehicle or construction-machinery tire. DESCRIPTION OF RELATED ART [0003] Radial-carcass tires for motor vehicles bearing heavy loads, in particular for heavy vehicles, comprise reinforcements which are formed of reinforcing threads or plies of metal wires coated with elastomers. More precisely, these tires comprise, in their bottom zone, one or more bead wires, a carcass reinforcement extending from one bead...

AI Technical Summary

Benefits of technology

[0024] makes it possible to obtain a rubber composition which has in the cross-linked state improved hysteresis properties at high deformations, in comparison with the hysteresis properties of known compositions comprising a grade 300 carbon black and having substantially one and the same modulus of elongation at low deformation.

Problems solved by technology

It is also known that coarse carbon blacks, such as the black N539, only impart sufficient cohesion to a heavy-vehicle carcass reinforcement composition if these blacks are present in this composition in a very large quantity, which may have the undesirable effect of adversely affecting the hysteresis of this composition.