Rubber composition for a tire crown reinforcement

1. A heavy-vehicle or construction vehicle tire, comprising a crown and a tread, the crown including a crown reinforcement comprising a cross-linkable or cross-linked rubber composition having a reduced hysteresis in the cross linked state, said composition comprising:

an elastomeric matrix comprising natural rubber or a synthetic polyisoprene in a majority proportion of the matrix, and

a reinforcing filler comprising a carbon black,

wherein said carbon black satisfies the following conditions:

(i) 50≦CTAB specific surface area in m 2 /g (in accordance with Standard ASTM D3765-80)≦55,

(ii) 45≦BET specific surface area in m 2 /g (in accordance with Standard 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)≦1.05,

(v) 115≦DBP structure value in ml/100 g (in accordance with Standard ASTM D2414-93)≦170,

(vi) 85≦Stokes diameter dst in nm≦145,

wherein 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,

wherein 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 D 50 being measured by centrifugal photosedimentometry.

2. The tire according to claim 1 , wherein said carbon black further satisfies the following condition:

(viii) 80≦DBPC structure value in ml/100 g (in accordance with Standard ASTM D3493-91)≦130,

wherein DBPC is measured after 4 compressions at 24,000 psi.

3. The tire according to claim 2 , wherein said condition (viii) is as follows:

(viii) 85≦DBPC structure value in ml/100 g≦125.

4. The tire according to claim 1 , wherein said conditions (ii) and (iii) are as follows:

(ii) 50≦BET specific surface area in m 2 /g≦65, and

(iii) 50≦iodine adsorption index IA in mg/g≦65.

5. The tire according to claim 1 , wherein said condition (v) is as follows:

(v) 120≦DBP structure value in ml/100 g≦165.

6. The tire according to claim 1 , wherein said condition (vi) is as follows:

(vi) 90≦Stokes diameter dst in nm≦140.

7. The tire according to claim 1 , wherein said condition (vii) is as follows:

(vii) D50/dst≧0.0092·CTAB+0.21.

8. The tire according to claim 1 , wherein said elastomeric matrix consists of natural rubber or synthetic polyisoprene.

9. The tire according to claim 1 , wherein said elastomeric matrix comprises a blend of natural rubber or synthetic polyisoprene and at least one additional diene elastomer,

wherein the diene elastomer is selected from the group consisting of polybutadienes, styrene-butadiene copolymers prepared in solution or in emulsion, butadiene-isoprene copolymers and styrene-butadiene-isoprene terpolymers,

wherein the natural rubber or synthetic polyisoprene is present in said composition in a quantity greater than 70 phr (phr: parts by weight per hundred parts of elastomers).

10. The tire according to claim 1 , wherein said carbon black represents the majority proportion of said reinforcing filler.

11. The tire according to claim 10 , wherein said reinforcing filler further comprises reinforcing inorganic filler.

12. The tire according to claim 11 , wherein said reinforcing inorganic filler is silica.

13. The tire according to claim 1 , wherein said carbon black is present in a quantity of from about 30 to about 70 phr.