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EP-4737514-A1 - RUBBER COMPOSITION AND TIRE

EP4737514A1EP 4737514 A1EP4737514 A1EP 4737514A1EP-4737514-A1

Abstract

Provided are a rubber composition and a tire that excel in heat resistance. The rubber composition contains a rubber component including an epoxidized diene-based rubber, a pyridine-based compound represented by the following formula (1), and a polycarboxylic acid compound: wherein R 1 to R 5 bound to a pyridine ring are the same as or different from each other and each represent a hydrogen atom or a monovalent organic group, and R 1 to R 5 may bind to each other and may form a ring structure.

Inventors

  • HOSOYA, Hiromu

Assignees

  • Sumitomo Rubber Industries, Ltd.

Dates

Publication Date
20260506
Application Date
20250922

Claims (14)

  1. A rubber composition comprising: a rubber component including an epoxidized diene-based rubber, a pyridine-based compound represented by the following formula (1), and a polycarboxylic acid compound: wherein R 1 to R 5 bound to a pyridine ring are the same as or different from each other and each represent a hydrogen atom or a monovalent organic group, and R 1 to R 5 may bind to each other and may form a ring structure.
  2. The rubber composition according to claim 1, further comprising a filler, wherein the rubber composition contains the filler in an amount of 50 parts by mass or more per 100 parts by mass of the rubber component.
  3. The rubber composition according to claim 1 or 2, further comprising carbon black.
  4. The rubber composition according to any one of claims 1 to 3, wherein the epoxidized diene-based rubber is an epoxidized isoprene-based rubber.
  5. The rubber composition according to any one of claims 1 to 4, further comprising zinc oxide.
  6. The rubber composition according to any one of claims 1 to 5, wherein at least one of R 1 to R 5 bound to a pyridine ring in the formula (1) is an amino group.
  7. The rubber composition according to any one of claims 1 to 6, wherein the amount of the polycarboxylic acid compound per 100 parts by mass of the rubber component in the rubber composition is 0.5 parts by mass or more and 3.0 parts by mass or less.
  8. The rubber composition according to any one of claims 1 to 7, wherein the amount of carbon black in the rubber composition per 100 parts by mass of the rubber component is 25 parts by mass or more and 80 parts by mass or less.
  9. The rubber composition according to any one of claims 1 to 8, wherein the amount of the epoxidized diene-based rubber based on 100% by mass of the rubber component in the rubber composition is 70% by mass or more.
  10. The rubber composition according to any one of claims 1 to 9, further comprising sulfur.
  11. The rubber composition according to any one of claims 1 to 10, wherein the polycarboxylic acid compound is a compound represented the following formula (I): HOOC-A-COOH (I) wherein A represents an optionally substituted divalent C1-C10 hydrocarbon group.
  12. The rubber composition according to any one of claims 1 to 11, wherein the polycarboxylic acid compound is a compound selected from the group consisting of maleic acid, fumaric acid, phthalic acid, malic acid, tartaric acid, suberic acid, citric acid, pyromellitic acid and mellitic acid.
  13. The rubber composition according to any one of claims 1 to 12, further comprising zinc oxide.
  14. A tire, comprising a tire component including the rubber composition according to any one of claims 1 to 13.

Description

TECHNICAL FIELD The present invention relates to rubber compositions and tires. BACKGROUND ART Tires are required to have various performances including fuel economy (see Patent Literature 1). Improvement of other properties such as heat resistance is also desired. CITATION LIST PATENT LITERATURE Patent Literature 1: JP 2019-65240 A SUMMARY OF INVENTION TECHNICAL PROBLEM The present invention aims to solve the problem and provide a resin composition and a tire that excel in heat resistance. SOLUTION TO PROBLEM The present invention relates to a rubber composition containing: a rubber component including an epoxidized diene-based rubber,a pyridine-based compound represented by the following formula (1), anda polycarboxylic acid compound: wherein R1 to R5 bound to a pyridine ring are the same as or different from each other and each represent a hydrogen atom or a monovalent organic group, and R1 to R5 may bind to each other and may form a ring structure. ADVANTAGEOUS EFFECTS OF INVENTION The rubber composition of the present invention contains a rubber component including an epoxidized diene-based rubber, a pyridine-based compound represented by the formula (1), and a polycarboxylic acid compound. This rubber composition can improve heat resistance. DESCRIPTION OF EMBODIMENTS The rubber composition contains a rubber component including an epoxidized diene-based rubber, a pyridine-based compound represented by the formula (1), and a polycarboxylic acid compound. The reason for the above-described effects of the rubber composition is not exactly clear, but it is believed as follows. The combination of a rubber component including an epoxidized diene-based rubber, a pyridine-based compound represented by the formula (1), and a polycarboxylic acid compound may form ionic bonds and/or hydrogen bonds. In particular, a reaction may be caused by an initial reaction between the epoxy moiety in the rubber and the pyridine-based compound. Since various substituents can be introduced in pyridine-based compounds, the reactivity of the pyridine-based compound can be easily controlled by varying the types of the substituents. Ionic bonds and hydrogen bonds, which are reversible bonds, can be recombined after they are broken by heat. Therefore, the rubber composition containing a combination of the specific components may improve heat resistance. The rubber composition contains a rubber component. The rubber component contributes to crosslinking and generally corresponds to a polymer component which has a weight average molecular weight (Mw) of 10000 or more and which is not extractable with acetone. The rubber component is solid under conditions of 1 atmosphere and room temperature (25°C). The weight average molecular weight of the rubber component is preferably 50000 or more, more preferably 150000 or more, still more preferably 200000 or more, particularly preferably 270000 or more, while it is preferably 2000000 or less, more preferably 1500000 or less, still more preferably 1000000 or less. When the weight average molecular weight is within the range indicated above, the advantageous effects tend to be better achieved. Herein, the weight average molecular weight (Mw) and the number average molecular weight (Mn) can be determined by gel permeation chromatography (GPC) (GPC-8000 series available from Tosoh Corporation, detector: differential refractometer, column: TSKgel SuperMultipore HZ-M available from Tosoh Corporation) and the determined values are calibrated with polystyrene standards. The rubber component may be either an unmodified rubber or a modified rubber. The modified rubber may be a rubber having a functional group interactive with fillers such as silica. Examples include a chain end-modified rubber obtained by modifying at least one chain end of a rubber with a compound (modifier) having the above functional group (i.e., a chain end-modified rubber terminated with the functional group); a backbone-modified rubber having the functional group in the backbone; a backbone- and chain end-modified rubber having the functional group in both the backbone and a chain end (e.g., a backbone- and chain end-modified rubber in which the backbone has the functional group and at least one chain end is modified with the modifier); and a chain end-modified rubber into which a hydroxy or epoxy group has been introduced by modification (coupling) with a polyfunctional compound having two or more epoxy groups in the molecule. Examples of the functional group include an amino group, an amide group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a urea group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a sulfide group, a disulfide group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imide group, a hydrazo group, an azo group, a diazo group, a carboxyl group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl