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EP-4737513-A1 - RUBBER COMPOSITION FOR TIRE, AND TIRE

EP4737513A1EP 4737513 A1EP4737513 A1EP 4737513A1EP-4737513-A1

Abstract

The object is to provide a rubber composition for a tire capable of achieving both high fuel efficiency and wear resistance of a tire, and the solution is a rubber composition for a tire containing a rubber component and carbon black having a cetyltrimethylammonium bromide (CTAB) adsorption specific surface area of 120 m 2 /g or more, wherein the rubber component includes a copolymer of cyclopentene and a norbornene compound represented by the following general formula (1): (in the formula, R 1 to R 4 each independently represent a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a substituent containing a halogen atom, a silicon atom, an oxygen atom, or a nitrogen atom, R 2 and R 3 may be bonded to each other to form a ring, and m is an integer of 0 to 2).

Inventors

  • TARUTANI Yasunori
  • HAMATANI SATOSHI
  • SAITO KOICHI
  • TAKAHASHI AYAKA
  • NAKATANI KENJI
  • YUKIMURA NORIAKI

Assignees

  • BRIDGESTONE CORPORATION

Dates

Publication Date
20260506
Application Date
20231207

Claims (11)

  1. A rubber composition for a tire comprising a rubber component and carbon black having a cetyltrimethylammonium bromide (CTAB) adsorption specific surface area of 120 m 2 /g or more, wherein the rubber component includes a copolymer of cyclopentene and a norbornene compound represented by general formula (1), shown below: where, in general formula (1), R 1 to R 4 each independently represent a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a substituent containing a halogen atom, a silicon atom, an oxygen atom, or a nitrogen atom, R 2 and R 3 may be bonded to each other to form a ring, and m is an integer of 0 to 2.
  2. The rubber composition for a tire according to claim 1, wherein the norbornene compound represented by general formula (1) is 2-norbornene and/or dicyclopentadiene.
  3. The rubber composition for a tire according to claim 1, wherein content of the copolymer of cyclopentene and the norbornene compound is 20 parts by mass to 90 parts by mass per 100 parts by mass of the rubber component.
  4. The rubber composition for a tire according to claim 1, wherein the copolymer of cyclopentene and the norbornene compound has a weight-average molecular weight (Mw) of 200,000 to 1,000,000.
  5. The rubber composition for a tire according to claim 1, wherein the copolymer of cyclopentene and the norbornene compound has a content ratio of structural units derived from cyclopentene of 20% by mass to 75% by mass.
  6. The rubber composition for a tire according to claim 2, wherein the copolymer of cyclopentene and the norbornene compound has a content ratio of structural units derived from 2-norbornene of 10% by mass to 60% by mass.
  7. The rubber composition for a tire according to claim 2, wherein the copolymer of cyclopentene and the norbornene compound has a content ratio of structural units derived from dicyclopentadiene of 10% by mass to 60% by mass.
  8. The rubber composition for a tire according to claim 1, wherein content of the carbon black is 5 parts by mass to 80 parts by mass per 100 parts by mass of the rubber component.
  9. The rubber composition for a tire according to claim 1, wherein the rubber component further includes butadiene rubber.
  10. The rubber composition for a tire according to claim 1, wherein the copolymer of cyclopentene and the norbornene compound is a terpolymer of cyclopentene, 2-norbornene, and dicyclopentadiene.
  11. A tire comprising the rubber composition for a tire according to claim 1.

Description

TECHNICAL FIELD The present disclosure relates to a rubber composition for a tire and a tire. BACKGROUND In connection with the recent global movement toward carbon dioxide emission regulations due to increasing concern over environmental issues, there is a growing demand for improved fuel efficiency in automobiles. To meet such demands, tire performance is also required to improve high fuel efficiency (that is, to reduce rolling resistance). In addition, from the perspective of tire economy, in the development of rubber compositions for tires, it is also required to improve wear resistance in addition to high fuel efficiency. However, in general, high fuel efficiency and wear resistance are in a trade-off relationship, and it is difficult to achieve both. For example, methods such as increasing the amount of filler, using fillers with fine particle size, or using high-structure fillers are known for improving wear resistance, but when these methods are adopted, although wear resistance is improved, there is a problem in that high fuel efficiency deteriorates. In response, PTL 1 and PTL 2 below disclose rubber compositions for passenger vehicle tires and rubber compositions for heavy-duty truck and bus tires containing specific long-chain branched cyclopentene ring-opening rubber (LCB-CPR), and these rubber compositions are said to be effective in reducing rolling resistance of tires, improving wet skid resistance, and improving wear resistance. CITATION LIST Patent Literature PTL 1: WO 2021/178233 A1PTL 2: WO 2021/178235 A1 SUMMARY (Technical Problem) However, as a result of investigations by the present inventors, it was found that even with the techniques described in PTL 1 and PTL 2 above, it is difficult to achieve both high fuel efficiency and wear resistance of tires, and there is still room for improvement. Therefore, the present disclosure has as its object to solve the above problems of the prior art and to provide a rubber composition for a tire capable of achieving both high fuel efficiency and wear resistance of a tire. Further, the present disclosure has as a further object to provide a tire achieving both high fuel efficiency and wear resistance. (Solution to Problem) The essential configuration of the rubber composition for a tire and the tire of the present disclosure for solving the above problems is as follows. [1] A rubber composition for a tire comprising a rubber component and carbon black having a cetyltrimethylammonium bromide (CTAB) adsorption specific surface area of 120 m2/g or more, wherein the rubber component includes a copolymer of cyclopentene and a norbornene compound represented by general formula (1), shown below: where, in general formula (1), R1 to R4 each independently represent a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a substituent containing a halogen atom, a silicon atom, an oxygen atom, or a nitrogen atom, R2 and R3 may be bonded to each other to form a ring, and m is an integer of 0 to 2.[2] The rubber composition for a tire according to [1], wherein the norbornene compound represented by general formula (1) is 2-norbornene and/or dicyclopentadiene.[3] The rubber composition for a tire according to [1] or [2], wherein content of the copolymer of cyclopentene and the norbornene compound is 20 parts by mass to 90 parts by mass per 100 parts by mass of the rubber component.[4] The rubber composition for a tire according to any one of [1] to [3], wherein the copolymer of cyclopentene and the norbornene compound has a weight-average molecular weight (Mw) of 200,000 to 1,000,000.[5] The rubber composition for a tire according to any one of [1] to [4], wherein the copolymer of cyclopentene and the norbornene compound has a content ratio of structural units derived from cyclopentene of 20% by mass to 75% by mass.[6] The rubber composition for a tire according to any one of [2] to [5], wherein the copolymer of cyclopentene and the norbornene compound has a content ratio of structural units derived from 2-norbornene of 10% by mass to 60% by mass.[7] The rubber composition for a tire according to any one of [2] to [6], wherein the copolymer of cyclopentene and the norbornene compound has a content ratio of structural units derived from dicyclopentadiene of 10% by mass to 60% by mass.[8] The rubber composition for a tire according to any one of [1] to [7], wherein content of the carbon black is 5 parts by mass to 80 parts by mass per 100 parts by mass of the rubber component.[9] The rubber composition for a tire according to any one of [1] to [8], wherein the rubber component further includes butadiene rubber.[10] The rubber composition for a tire according to any one of [1] to [9], wherein the copolymer of cyclopentene and the norbornene compound is a terpolymer of cyclopentene, 2-norbornene, and dicyclopentadiene.[11] A tire comprising the rubber composition for a tire according to any one of [1] to [10]. (Advantageous Effect) According to the pr