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EP-4735268-A1 - TYRE HAVING A LESS TEMPERATURE-SENSITIVE ROLLING RESISTANCE

EP4735268A1EP 4735268 A1EP4735268 A1EP 4735268A1EP-4735268-A1

Abstract

The invention relates to a tyre (10) comprising a tread (12) comprising a tread layer (20) comprising: - a central portion (24) comprising a central elastomeric material (240) having a glass transition temperature Tgc, the central portion (24) extending axially on either side of a median plane (M) of the tyre (10), - at least one first lateral portion (26) comprising a first lateral elastomeric material (260) having a glass transition temperature Tgl1. Tgc ≤ -10°C, Tgl1 ≤ -10°C and 12°C ≤ Tgc-Tgl1 ≤ 23°C.

Inventors

  • FRANCOIS, Marie Laure
  • FERNANDEZ, MIGUEL

Assignees

  • COMPAGNIE GENERALE DES ETABLISSEMENTS MICHELIN

Dates

Publication Date
20260506
Application Date
20240223

Claims (15)

  1. 1. A tire (10) comprising a tread (12) axially delimited by first and second axial edges (16, 18), the tread (12) comprising a tread layer (20) comprising: - a central portion (24) extending between first and second axial edges (30, 32) of the central portion (24), the central portion (24) comprising at least one central elastomeric material (240) having a glass transition temperature Tgc, the central portion (24) extending axially on either side of a median plane (M) of the tire (10), - at least one first lateral portion (26) extending between the first axial edge (16) of the tread (12) and the first axial edge (30) of the central portion (24), the first lateral portion (26) comprising at least one first lateral elastomeric material (260) having a glass transition temperature Tgl1, characterized in that Tgc < -10°C, Tgl1 < -10°C and 12°C < Tgc-Tgl1 < 23°C.
  2. 2. Tire (10) according to the preceding claim, in which Tgc-Tgl1 > 13°C, preferably Tgc-Tgl1 > 14°C.
  3. 3. Tire (10) according to any one of the preceding claims, in which Tgc-Tgl1 < 22°C, preferably Tgc-Tgl1 < 20°C and more preferably Tgc-Tgl1 < 18°C.
  4. 4. Tire (10) according to any one of the preceding claims, in which Tgc > -18°C, preferably Tgc > -15°C and more preferably Tgc > -13°C.
  5. 5. A tire (10) according to any preceding claim, wherein Tgl1 < -15°C, preferably Tgl1 < -20°C.
  6. 6. Tire (10) according to any one of the preceding claims, in which Tgl 1 > -35°C, preferably Tgl 1 > -30°C and more preferably Tgl 1 > -27°C.
  7. 7. A tire (10) according to any preceding claim, wherein: - the central elastomeric material (240) having a complex dynamic shear modulus G*C measured at 10% deformation according to the ASTM D- 5992-96 standard, at a temperature of 23°C and at a frequency of 10Hz, - the first lateral elastomeric material (260) having a complex dynamic shear modulus G*I1 measured at 10% deformation according to the ASTM D- 5992-96 standard, at a temperature of 23°C and at a frequency of 10Hz, G*C>G*I1.
  8. 8. Tire (10) according to the preceding claim, in which G*C > 1.7 MPa, preferably G*C > 2.3 MPa and more preferably G*C > 2.5 MPa.
  9. 9. Tire (10) according to claim 7 or 8, in which G*I1 > 1.3 MPa, preferably G*I1 > 1.5 MPa and more preferably G*I1 > 1.7 MPa.
  10. 10. A tire (10) according to any preceding claim, wherein the tread layer (20) comprises a second lateral portion (28) extending between the second axial edge (18) of the tread (12) and the second axial edge (32) of the central portion (24), the second lateral portion (28) comprising at least one second lateral elastomeric material (280) having a glass transition temperature Tgl2 such that Tgl2 < -10°C and 12°C < Tgc-Tgl2 < 23°C.
  11. 11. Tire (10) according to the preceding claim, in which Tgc-Tgl2 > 13°C, preferably Tgc-Tgl2 > 14°C.
  12. 12. Tire (10) according to claim 10 or 11, in which Tgc-Tgl2 < 22°C, preferably Tgc-Tgl2 < 20°C and more preferably Tgc-Tgl2 < 18°C.
  13. 13. A tire (10) according to any one of claims 10 to 12, in which Tgl2 < -15°C, preferably Tgl2 < -20°C.
  14. 14. Tire (10) according to any one of claims 10 to 13, in which Tgl2 > -35°C, preferably Tgl2 > -30°C and more preferably Tgl2 > -27°C.
  15. 15. Use of a tire (10) according to any one of the preceding claims for an electric or hybrid vehicle, preferably an electric vehicle.

Description

Tire with rolling resistance less sensitive to temperature [001] The present invention relates to a tire. By tire is meant a bandage intended to form a cavity by cooperating with a support element, for example a rim, this cavity being capable of being pressurized to a pressure higher than atmospheric pressure. A tire according to the invention has a structure of substantially toroidal shape of revolution around a main axis of the tire. [002] The state of the art discloses a summer tire for a passenger vehicle comprising a tread intended to come into contact with the ground when the tire is rolling via a rolling surface. The tread comprises a tread layer and a support layer arranged at least partly radially inside the tread layer. Such a tire is described in particular in WO2021/111083. [003] Users have noticed that passenger vehicles on which these tires were fitted, particularly electric vehicles, exhibit a significant drop in autonomy when the temperature is low, and this is even more the case when the temperature drop is significant. [004] The invention therefore aims to make the autonomy of vehicles less sensitive to a drop in temperature. [005] For this purpose, the invention relates to a tire comprising a tread delimited axially by first and second axial edges, the tread comprising a tread layer comprising: - a central portion extending between first and second axial edges of the central portion, the central portion comprising at least one central elastomeric material having a glass transition temperature Tgc, the central portion extending axially on either side of a median plane of the tire, - at least one first lateral portion extending between the first axial edge of the tread and the first axial edge of the central portion, the first lateral portion comprising at least one first lateral elastomeric material having a glass transition temperature Tgl 1 , a tire in which Tgc < -10°C, Tgl1 < -10°C and 12°C < Tgc-Tgl1 < 23°C. [006] Indeed, the inventors behind the invention discovered that the drop in temperature led to a significant increase in rolling resistance, an increase that was all the more significant the lower the temperature. However, rolling resistance has an effect on the autonomy of the vehicle. Thus, the invention makes it possible to make the autonomy of vehicles less sensitive to a drop in temperature. The tires according to the invention thus make it possible to drive in a relatively wide temperature range, for example from 25°C to -7°C, with rolling resistance less sensitive to temperature. [007] Once this effect was discovered, the inventors had to find a way to reduce the influence of temperature on rolling resistance. This is made possible by using a central elastomeric material and at least the first lateral elastomeric material having both relatively low glass transition temperatures, here such that Tgc < -10°C, Tgl1 < -10°C and at the same time sufficiently different, here such that 12°C < Tgc-Tgl1 < 23°C. [008] In addition to reducing the influence of temperature on rolling resistance as shown by the tests described in the present application, the characteristics of the tire materials show an amplification of the reduction of the influence of temperature on rolling resistance with the drop in temperature. This result is unexpected because it contradicts the observation made according to which the rolling resistance of the tire of the state of the art increases all the more as the temperature drops. This unexpected result therefore makes it possible to at least partially compensate for the increase in rolling resistance with the drop in temperature. [009] The characteristic according to which Tgc < -10°C, Tgl1 < -10°C makes it possible to prevent, for very low operating temperatures, for example -5°C or even -7°C, the elastomeric materials from dissipating too much energy. Indeed, the closer the operating temperature is to the glass transition, the more the material dissipates energy and increases the rolling resistance of the tire. This is particularly important for at least the first lateral elastomeric material which contributes mainly to the rolling resistance due to its positioning on the tread. Indeed, by being positioned axially laterally, the first lateral portion requires significant efforts to flatten the tire and therefore dissipates more energy. [010] Too great a difference between the temperatures Tgc and Tgl1 would, for a given temperature Tgc, result in a reduction in the wet braking performance of the tire. Indeed, a relatively low temperature Tgl1 of the lateral portion would result in a reduction in the wet braking performance of the tire. [011] For a given temperature Tgl1, too large a difference between the temperatures Tgc and Tgl1 would lead to a relatively high temperature Tgc and therefore to a decrease in rolling resistance performance for very low operating temperatures as explained above. Thus, the invention also makes it possible to preserve the ti