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EP-4349616-B1 - RUBBER COMPOSITION FOR TIRE, TREAD RUBBER, AND TIRE

EP4349616B1EP 4349616 B1EP4349616 B1EP 4349616B1EP-4349616-B1

Inventors

  • KAWASHIMA, MASAHIRO

Dates

Publication Date
20260506
Application Date
20220331

Claims (10)

  1. A rubber composition for tire, comprising a rubber component, a resin component, and a filler, wherein the rubber component comprises a diene-based rubber component A with a glass transition temperature of -50 °C or lower that contains an isoprene skeleton rubber, and a diene-based rubber component B incompatible with the diene-based rubber component A that contains a butadiene skeleton rubber, a total styrene content in the diene-based rubber component B is 15 % by mass or less, the resin component has a weight-average molecular weight, which is indicated by Mw, of 200 g/mol to 1600 g/mol, and a content of the resin component is 1 part by mass to 45 parts by mass with respect to 100 parts by mass of the rubber component, a content of the filler is 20 parts by mass to 120 parts by mass with respect to 100 parts by mass of the rubber component, and a ratio of tanδ at 0 °C, which is 0 °C tanδ, to tanδ at 50 °C, which is 50 °C tanδ, is 2.7 or more, where the ratio is indicated by 0 °C tanδ/50 °C tanδ.
  2. The rubber composition for tire according to claim 1, wherein a content ratio of the diene-based rubber component A in the rubber component is 1 % by mass or more and less than 50 % by mass.
  3. The rubber composition for tire according to claim 1 or 2, wherein the resin component has a softening point higher than 110 °C.
  4. The rubber composition according to any one of claims 1 to 3, wherein the diene-based rubber component A comprises at least one selected from the group consisting of natural rubber and isoprene rubber.
  5. The rubber composition according to any one of claims 1 to 4, wherein the diene-based rubber component B comprises at least one selected from the group consisting of styrene-butadiene rubber and butadiene rubber.
  6. The rubber composition for tire according to claim 5, wherein the styrene-butadiene rubber is modified with a modifying agent having a functional group containing a nitrogen atom and an alkoxy group.
  7. The rubber composition according to any one of claims 1 to 6, wherein the filler contains carbon black.
  8. The rubber composition according to any one of claims 1 to 7, wherein the resin component comprises at least one selected from the group consisting of a hydrogenated C5-based resin, a hydrogenated C5-C9-based resin, a hydrogenated dicyclopentadiene-based resin which is hydrogenated DCPD-based resin, and a hydrogenated terpene-based resin.
  9. A tread rubber, comprising the rubber composition for tire according to any one of claims 1 to 8.
  10. A tire, comprising the tread rubber according to claim 9.

Description

TECHNICAL FIELD This disclosure relates to a rubber composition for tire, a tread rubber, and a tire. BACKGROUND Various studies have conventionally been made to improve braking performance on a wet road surface (hereinafter, abbreviated as "wet grip performance") from the viewpoint of improving vehicle safety. For example, WO/2015/079703 (PTL 1) describes that a rubber composition, which is obtained by blending a thermoplastic resin and a filler containing silica with a rubber component containing 70 % by mass or more of natural rubber, is applied to a tread rubber of a tire to improve the braking performance of the tire on both a dry road surface and a wet road surface. On the other hand, in response to global moves to regulate carbon dioxide emissions with the increased interest in environmental problems in recent years, demand to improve the fuel efficiency of automobiles is growing. To meet such demand, improvement in fuel efficiency (reduction in rolling resistance) is required in terms of tire performance. CITATION LIST Patent Literature PTL 1: WO/2015/079703 SUMMARY (Technical Problem) However, we have studied the technique described in PTL 1 and found that, although the wet grip performance of a tire can be improved, there is room for improvement in fuel efficiency. It could thus be helpful to provide a rubber composition for tire which can solve the problem of the prior art and can highly balance wet grip performance with fuel efficiency in a tire, as well as a tread rubber containing the rubber composition. It also could be helpful to provide a tire in which wet grip performance is highly balanced with fuel efficiency. (Solution to Problem) We thus provide the following. A rubber composition for tire of the present disclosure is a rubber composition for tire containing a rubber component, a resin component, and a filler, where the rubber component contains a diene-based rubber component A with a glass transition temperature of -50 °C or lower that contains an isoprene skeleton rubber, and a diene-based rubber component B incompatible with the diene-based rubber component A that contains a butadiene skeleton rubber,the total styrene content in the diene-based rubber component B is 15 % by mass or less,the resin component has a weight-average molecular weight (Mw) of 200 g/mol to 1600 g/mol, and the content of the resin component is 1 part by mass to 45 parts by mass with respect to 100 parts by mass of the rubber component,the content of the filler is 20 parts by mass to 120 parts by mass with respect to 100 parts by mass of the rubber component, anda ratio of tanδ at 0 °C (0 °C tanδ) to tanδ at 50 °C (50 °C tanδ) (0 °C tanδ/50 °C tanδ) is 2.7 or more. By applying the rubber composition for tire of the present disclosure to a tire, it is possible to highly balance wet grip performance with fuel efficiency in the tire. The weight-average molecular weight of the resin component is measured by gel permeation chromatography (GPC) and calculated as a polystyrene-equivalent value. Further, a tread rubber of the present disclosure contains the rubber composition for tire described above. By applying the tread rubber of the present disclosure to a tire, it is possible to highly balance wet grip performance with fuel efficiency in the tire. Further, a tire of the present disclosure includes the tread rubber described above. In the tire of the present disclosure, wet grip performance is highly balanced with fuel efficiency. (Advantageous Effect) According to the present disclosure, it is possible to provide a rubber composition for tire capable of highly balancing wet grip performance with fuel efficiency in a tire, and a tread rubber containing the rubber composition. Further, according to the present disclosure, it is possible to provide a tire in which wet grip performance is highly balanced with fuel efficiency. DETAILED DESCRIPTION The following describes the rubber composition for tire, the tread rubber, and the tire of the present disclosure in detail based on their embodiments. <Rubber composition for tire> The rubber composition for tire of the present disclosure is a rubber composition for tire containing a rubber component, a resin component, and a filler, where the rubber component contains a diene-based rubber component A with a glass transition temperature of -50 °C or lower that contains an isoprene skeleton rubber, and a diene-based rubber component B incompatible with the diene-based rubber component A that contains a butadiene skeleton rubber. In the present disclosure, the total styrene content in the diene-based rubber component B is 15 % by mass or less, the resin component contains 1 part by mass to 45 parts by mass of a resin with respect to 100 parts by mass of the rubber component, where the resin has a weight-average molecular weight (Mw) of 200 g/mol to 1600 g/mol,the content of the filler is 20 parts by mass to 120 parts by mass with respect to 100 parts by mass of the rubber com