Tire comprising a layer of circumferential reinforcing elements
Tire comprising a crown reinforcement formed of at least two working crown layers of reinforcing elements, a first layer C of rubber compound being placed between at least the ends of the said at least two working crown layers, a second layer S of polymer compound being in contact with at least one working crown layer and in contact with the carcass reinforcement and the crown reinforcement comprising at least one layer of circumferential reinforcing elements. The elastic modulus under tension at 10% elongation of the first layer C is less than 8 MPa, the maximum tan(δ) value, denoted tan(δ) max , of the first layer C is less than 0.100, and the complex dynamic shear modulus G*, measured at 10% and 60° C. on the return cycle, of the said second layer S of polymer compound is greater than 1.35 MPa.
1. Tire with a radial carcass reinforcement comprising a crown reinforcement formed of at least two working crown layers of reinforcing elements, crossed from one layer to the other making with the circumferential direction angles comprised between 10° and 45°, a first layer of rubber compound being placed between at least the ends of said at least two working crown layers, a second layer of polymer compound being in contact with at least one working crown layer and in contact with the carcass reinforcement, said second layer of polymer compound extending axially as far as at least the axial end of the tread, said tread radially capping the crown reinforcement and being connected to two beads by two sidewalls, the crown reinforcement comprising at least one layer of circumferential metal reinforcing elements, wherein the elastic modulus under tension at 10% elongation of the first layer of rubber compound is less than 8 MPa wherein the maximum value of tan(δ), denoted tan(δ) max , of the first layer of rubber compound is less than 0.100, and wherein the complex dynamic shear modulus, measured at 10% and 60° C. on the return cycle, of said second layer of polymer compound is greater than 1.35 MPa,
wherein the tire comprises an additional layer of polymer compound axially in contact with the second layer of polymer compound radially between the carcass reinforcement and the radially innermost layer of reinforcing elements of the crown reinforcement, and
wherein the complex dynamic shear modulus, measured at 10% and 60° C. on the return cycle, of said additional layer of polymer compound is greater than 1.35 MPa.
2. The tire according to claim 1 , wherein the complex shear modulus, measured at 10% and 60° C. on the return cycle, of the second layer of polymer compound is less than 2 MPa.
3. The tire according to claim 1 , wherein the maximum value of tan(δ), denoted tan(δ)max, of the second layer of polymer compound is less than 0.100.
4. The tire according to claim 1 , wherein the said second layer of polymer compound comprises a reinforcing filler made up of:
a) either carbon black with a BET specific surface area of between 30 and 160 m 2 /g, used in a content equal to or greater than 15 phr and less than or equal to 28 phr,
b) or a white filler of the silica and/or alumina type comprising SiOH and/or AlOH surface functional groups selected from the group formed of precipitated or pyrogenated silicas, aluminas or aluminosilicates or alternatively carbon blacks modified during or after synthesis with a specific surface area of between 30 and 260 m 2 /g used at a content greater than or equal to 15 phr and less than or equal to 55 phr,
c) or a blend of carbon black described at (a) and a white filler described at (b), in which the overall filler content is greater than or equal to 15 phr and less than equal to 50 phr and the white filler phr content is greater than or equal to the phr content of carbon black minus 5.
5. The tire according to claim 1 , wherein the first layer of rubber compound is an elastomeric compound based on natural rubber or synthetic polyisoprene with a majority of cis-1,4 chains, and possibly at least one other diene elastomer, the natural rubber or the synthetic polyisoprene in case of blending being present in a majority proportion relative to the proportion of the other diene elastomer or elastomers used, and a reinforcing filler composed of:
a) either carbon black with a BET specific surface area greater than 60 m 2 /g,
i. used at a content of between 20 and 40 phr when the carbon black oil absorption number (COAN) is greater than 85,
ii. used at a content comprised between 20 and 60 phr when the carbon black oil absorption number (COAN) is less than 85,
b) or carbon black of BET specific surface area less than 60 m 2 /g, whatever its oil absorption number, used at a content of between 20 and 80 phr,
c) or a white filler of the silica and/or alumina type comprising SiOH and/or AlOH surface functional groups selected from the group formed of precipitated or pyrogenated silicas, aluminas or aluminosilicates or alternatively carbon blacks modified during or after synthesis with BET specific surface area of between 30 and 260 m 2 /g used at a content of between 20 and 80 phr,
d) or a blend of carbon black described at (a) and/or of carbon black described at (b) and/or a white filler described at (c), in which the overall filler content is comprised between 20 and 80 phr.
6. The tire according to claim 1 , said at least two working crown layers having unequal axial widths, wherein a third layer of rubber compound separates the axially widest working crown layer from the end of the second working crown layer, wherein the axially outer end of said third layer of rubber compound is situated at a distance away from the equatorial plane of the tire that is less than the distance separating the end of the axially widest reinforcing elements ply from said plane, wherein said third layer P of rubber compound is radially separated at least in part from the skim of said working crown layer by the first layer of rubber compounds, and wherein said first and second layers of rubber compound and said skim respectively have elastic modulus values under tension at 10% elongation denoted MP, MC and ML, such that ML≥MC>MP.
7. The tire according to claim 1 , wherein the complex shear modulus, measured at 10% and 60° C. on the return cycle, of the additional layer is less than 2 MPa.
8. The tire according to claim 1 , wherein the maximum value of tan(δ), denoted tan(δ)max, of the additional layer is less than 0.100.
9. The tire according to claim 1 , wherein said additional layer of polymer compound comprises a reinforcing filler made up of:
a) either carbon black with a BET specific surface area of between 30 and 160 m 2 /g, used in a content equal to or greater than 15 phr and less than or equal to 28 phr,
b) or a white filler of the silica and/or alumina type comprising SiOH and/or AlOH surface functional groups selected from the group formed of precipitated or pyrogenated silicas, aluminas or aluminosilicates or alternatively carbon blacks modified during or after synthesis with a specific surface area of between 30 and 260 m 2 /g used at a content greater than or equal to 15 phr and less than or equal to 55 phr,
c) or a blend of carbon black described at (a) and a white filler described at (b), in which the overall filler content is greater than or equal to 15 phr and less than equal to 50 phr and the white filler phr content is greater than or equal to the phr content of carbon black minus 5.
10. The tire according to claim 1 , said at least two working crown layers each being formed of reinforcing elements inserted between two skim layers of rubber compound, wherein the elastic modulus under tension at 10% elongation of at least one skim layer of at least one working crown layer is less than 8.5 MPa and wherein the maximum value of tan(δ), denoted tan(δ)max, of said at least one skim layer of at least one working crown layer is less than 0.100.
11. The tire according to claim 10 , wherein said at least one skim layer of at least one working crown layer is an elastomer compound based on natural rubber or based on synthetic polyisoprene with a predominance of cis-1,4 chains and possibly at least one other diene elastomer, natural rubber or synthetic polyisoprene in the case of a blend being present at a content that predominates over the content of the other diene elastomer or elastomers used and of a reinforcing filler made up of:
a) either carbon black of BET specific surface area greater than 60 m 2 /g,
i. used at a content of between 20 and 40 phr when the oil absorption number (COAN) of the carbon black is greater than 85,
ii. used at a content of between 20 and 60 phr when the oil absorption number (COAN) of the carbon black is less than 85,
b) or carbon black with BET specific surface area less than 60 m 2 /g whatever its oil absorption number, used at a content of between 30 and 50 phr,
c) or a white filler of the silica and/or alumina type comprising SiOH and/or AlOH functional groups at the surface, selected from the group formed of precipitated or pyrogenated silicas, aluminas or aluminosilicates or alternatively still carbon blacks modified during or after the synthesis with BET specific surface area of between 30 and 260 m 2 /g used at a content of between 30 and 50 phr,
d) or a blend of carbon black described at (a) and/or of carbon black described at (b) and/or a white filler described at (c), in which blend the overall filler content is between 40 and 60 phr.
12. The tire according to claim 10 , wherein said at least one skim layer of at least one working crown layer is an elastomer compound based on natural rubber or based on synthetic polyisoprene with a predominance of cis-1,4 chains and possibly at least one other diene elastomer, natural rubber or synthetic polyisoprene in the case of a blend being present at a content that predominates over the content of the other diene elastomer or elastomers used and of a reinforcing filler made up of:
a) either carbon black of BET specific surface area greater than 60 m 2 /g,
i. used at a content of between 20 and 40 phr when the oil absorption number (COAN) of the carbon black is greater than 85,
ii. used at a content of between 20 and 60 phr when the oil absorption number (COAN) of the carbon black is less than 85,
b) or carbon black with BET specific surface area less than 60 m 2 /g whatever its oil absorption number, used at a content of between 20 and 80 phr,
c) or a white filler of the silica and/or alumina type comprising SiOH and/or AlOH functional groups at the surface, selected from the group formed of precipitated or pyrogenated silicas, aluminas or aluminosilicates or alternatively still carbon blacks modified during or after the synthesis with BET specific surface area of between 30 and 260 m 2 /g used at a content of between 20 and 80,
d) or a blend of carbon black described at (a) and/or of carbon black described at (b) and/or a white filler described at (c), in which blend the overall filler content is between 20 and 80 phr.
13. The tire according to claim 1 , wherein said reinforcing elements of at least one working crown layer are cords with saturated layers, at least one internal layer being sheathed by a layer made of a polymer composition such as a non-crosslinkable, crosslinkable or crosslinked rubber composition.
14. The tire according to claim 1 , wherein the layer of circumferential reinforcing elements is placed radially between two working crown layers.
15. The tire according to claim 1 , wherein the reinforcing elements of at least one layer of circumferential reinforcing elements are metallic reinforcing elements having a secant modulus at 0.7% elongation comprised between 10 and 120 GPa and a maximum tangent modulus less than 150 GPa.
16. The tire according to claim 1 , wherein the reinforcing elements of the working crown layers are inextensible.
17. The tire according to claim 1 , wherein the first layer of rubber compound is an elastomeric compound based on natural rubber or synthetic polyisoprene with a majority of cis-1,4 chains, and possibly at least one other diene elastomer, the natural rubber or the synthetic polyisoprene in case of blending being present in a majority proportion relative to the proportion of the other diene elastomer or elastomers used, and a reinforcing filler composed of:
a) either carbon black with a BET specific surface area greater than 60 m 2 /g,
i. used at a content of between 20 and 40 phr when the carbon black oil absorption number (COAN) is greater than 85,
ii. used at a content comprised between 20 and 60 phr when the carbon black oil absorption number (COAN) is less than 85,
b) or carbon black of BET specific surface area less than 60 m 2 /g, whatever its oil absorption number, used at a content of between 30 and 50 phr,
c) or a white filler of the silica and/or alumina type comprising SiOH and/or AlOH surface functional groups selected from the group formed of precipitated or pyrogenated silicas, aluminas or aluminosilicates or alternatively carbon blacks modified during or after synthesis with BET specific surface area of between 30 and 260 m 2 /g used at a content of between 30 and 50 phr,
d) or a blend of carbon black described at (a) and/or of carbon black described at (b) and/or a white filler described at (c), in which the overall filler content is comprised between 40 and 60 phr.
18. The tire according to claim 1 , wherein said reinforcing elements of at least one working crown layer are cords with saturated layers, at least one internal layer being sheathed by a layer made of a polymer composition such as a non-crosslinkable, crosslinkable or crosslinked rubber composition based on at least one diene elastomer.