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EP-4737516-A1 - RUBBER COMPOSITION FOR TIRES, AND TIRE

EP4737516A1EP 4737516 A1EP4737516 A1EP 4737516A1EP-4737516-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 not less than 35 m 2 /g and not more than 100 m 2 /g, 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

  • FUKASAWA Rira
  • NISHIMURA SYUNSUKE
  • YAMADA HIROSHI
  • TARUTANI Yasunori

Assignees

  • BRIDGESTONE CORPORATION

Dates

Publication Date
20260506
Application Date
20231207

Claims (10)

  1. A rubber composition for a tire comprising a rubber component and carbon black having a cetyltrimethylammonium bromide (CTAB) adsorption specific surface area of not less than 35 m 2 /g and not more than 100 m 2 /g, wherein the rubber component includes a copolymer of cyclopentene and a norbornene compound represented by general formula (1), shown below: where, in the 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. 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 regulation of carbon dioxide emissions due to heightened interest in environmental issues, there is an increasing demand for improved fuel efficiency in automobiles. In order to meet such demands, improvement in tire performance, specifically enhancement of high fuel efficiency (i.e., reduction of rolling resistance), is also required. Furthermore, from the perspective of tire economy, in the development of rubber compositions for tires, in addition to high fuel efficiency, improvement of wear resistance is also required. In response to these demands, conventionally, improvement of wear resistance has been attempted by enhancing the affinity between the rubber component and the filler, for example, by modifying the rubber component or using chemicals; however, it has not been possible to significantly improve wear resistance. Also, for example, a method of increasing the amount of filler blended in order to improve wear resistance is known, but increasing the amount of filler leads to deterioration in the dispersion state of the filler, resulting in a problem of worsened high fuel efficiency. As such, in general, high fuel efficiency and wear resistance are in a trade-off relationship, and it is difficult to achieve both. 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, which contain a 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 a tire, and there remains room for improvement. Accordingly, the present disclosure has as its object to provide a rubber composition for a tire capable of achieving both high fuel efficiency and wear resistance of a tire, thereby solving the problems of the prior art described above. Furthermore, the present disclosure has as a further object to provide a tire in which both high fuel efficiency and wear resistance are achieved. (Solution to Problem) The essential configuration of the rubber composition for a tire and the tire of the present disclosure that solves 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 not less than 35 m2/g and not more than 100 m2/g, 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 the 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