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EP-4047048-B1 - PARTICLE DISPERSION, RUBBER COMPOSITION, AND PNEUMATIC TIRE

EP4047048B1EP 4047048 B1EP4047048 B1EP 4047048B1EP-4047048-B1

Inventors

  • KAGEYAMA HIROKAZU
  • KIMURA KAZUSHI

Dates

Publication Date
20260513
Application Date
20201016

Claims (15)

  1. A particle dispersion comprising particles formed from a polymer that are dispersed in a diene polymer A having a number average molecular weight from 1000 to 100000, the polymer forming the particles being a polymer C that is not a diene polymer, and the particles being surface-modified with a hydrocarbon group having from 3 to 30 carbons and/or a diene polymer D, and the hydrocarbon group having from 3 to 30 carbons or the diene polymer D being each independently bonded to the polymer C forming the particles through a urea bond, a urethane bond, or an amide bond; wherein the number average molecular weight is a standard polystyrene conversion value obtained by gel permeation chromatography measurement using tetrahydrofuran as solvent and a RI detector.
  2. The particle dispersion according to claim 1, wherein the diene polymer A having a number average molecular weight from 1000 to 100000 contains at least one type of unmodified diene polymer selected from the group consisting of unmodified isoprene homopolymers, butadiene homopolymers, acrylonitrile-butadiene polymers, styrene-butadiene polymers, styrene-isoprene polymers, and styrene-isoprene-butadiene polymers, and a content of the unmodified diene polymer is 50 mass% or greater based on the total amount of the diene polymer A having a number average molecular weight from 1000 to 100000; wherein the number average molecular weight is a standard polystyrene conversion value obtained by gel permeation chromatography measurement using tetrahydrofuran as solvent and a RI detector.
  3. The particle dispersion according to claim 1 or 2, wherein an average particle diameter of the particles that are surface-modified is from 0.01 to 200 µm; wherein the average particle diameter is measured by a laser diffraction particle size distribution analyzer.
  4. The particle dispersion according to any one of claims 1 to 3, wherein a content of the particles that are surface-modified is from 1 to 300 parts by mass based on 100 parts by mass of the diene polymer A having a number average molecular weight from 1000 to 100000; wherein the number average molecular weight is a standard polystyrene conversion value obtained by gel permeation chromatography measurement using tetrahydrofuran as solvent and a RI detector.
  5. The particle dispersion according to any one of claims 1 to 4, wherein the hydrocarbon group is formed only from a carbon atom and a hydrogen atom.
  6. The particle dispersion according to any one of claims 1 to 5, wherein the hydrocarbon group is a monovalent hydrocarbon group.
  7. The particle dispersion according to any one of claims 1 to 6, wherein the hydrocarbon group is an aliphatic hydrocarbon group that may have an unsaturated bond.
  8. The particle dispersion according to any one of claims 1 to 7, wherein the hydrocarbon group is an alkyl group or an alkenyl group.
  9. The particle dispersion according to any one of claims 1 to 8, wherein the hydrocarbon group is bonded to the polymer C forming the particles through the urea bond or the urethane bond.
  10. The particle dispersion according to any one of claims 1 to 9, wherein the diene polymer D is bonded to the polymer C forming the particles through the amide bond.
  11. A method of producing a particle dispersion, the method producing the particle dispersion according to any one of claims 1 to 10, the method comprising: micelle forming of obtaining a micelle dispersion containing a micelle of a polymer E, the polymer E not being a diene polymer and containing an isocyanate group, an amino group, or an imino group, by dispersing the polymer E in a diene polymer A having a number average molecular weight from 1000 to 100000 in the presence of a surfactant, and surface-modifying by, in a case where the polymer E in the micelle dispersion contains an isocyanate group, adding a compound F containing a hydrocarbon group having from 3 to 30 carbons, and a hydroxy group, an amino group, or an imino group, and/or a diene polymer G containing a hydroxy group, an amino group, or an imino group in the micelle dispersion, reacting the isocyanate group contained in the micelle and the compound F and/or the diene polymer G, and modifying a surface of the micelle with the hydrocarbon group and/or the diene polymer D through a urethane bond or a urea bond, or in a case where the polymer E in the micelle dispersion contains an amino group or an imino group, adding a compound H containing a hydrocarbon group having from 3 to 30 carbons and a carboxy group or an acid anhydride group, and/or a diene polymer I containing a carboxy group or an acid anhydride group in the micelle dispersion, reacting the amino group or the imino group contained in the micelle and the compound H and/or the diene polymer I, and modifying a surface of the micelle with the hydrocarbon group and/or the diene polymer D through an amide bond; wherein the number average molecular weight is a standard polystyrene conversion value obtained by gel permeation chromatography measurement using tetrahydrofuran as solvent and a RI detector.
  12. A rubber composition comprising a diene rubber X and the particle dispersion according to any one of claims 1 to 10.
  13. The rubber composition according to claim 12, wherein a content of the particle dispersion is from 1 to 150 parts by mass based on 100 parts by mass of the diene rubber X.
  14. The rubber composition according to claim 12 or 13, further comprising at least one type of filler selected from the group consisting of carbon black and white fillers, a content of the filler being from 1 to 200 parts by mass based on 100 parts by mass of the diene rubber X.
  15. A pneumatic tire produced by using the rubber composition according to any one of claims 12 to 14.

Description

Technical Field The present invention relates to a particle dispersion, a rubber composition, and a pneumatic tire. Background Art In the related art, a rubber composition for a tire, the rubber composition containing microparticles to enhance performance on ice and wear resistance, has been proposed (e.g., Patent Document 1). Patent Document 1 describes a rubber composition for a tire, the rubber composition containing 100 parts by mass of a diene rubber (A), from 30 to 100 parts by mass of carbon black and/or white filler (B),from 0.3 to 30 parts by mass of a crosslinkable oligomer or polymer (C) that is miscible with the diene rubber (A) and that is different from the diene rubber (A), andfrom 0.3 to 12 parts by mass of a three-dimensionally crosslinked microparticles (D) having an average particle diameter from 1 to 200 µm,the crosslinkable oligomer or polymer (C) being a liquid diene polymer (claim 1), andthe microparticles (D) being microparticles obtained by three-dimensionally crosslinking an oligomer or polymer (d1) that is not miscible with the crosslinkable oligomer or polymer (C) in advance in the crosslinkable oligomer or polymer (C) (claim 2). Patent Document 2 discloses a tire rubber composition and a pneumatic tire using the same. The tire rubber composition includes 100 parts by mass of a diene rubber (A) and from 1 to 50 parts by mass of elastic microparticles (B), wherein the elastic microparticles (B) have a form of microparticles obtained by crosslinking a crosslinkable oligomer or polymer (b1) in water or an organic solvent, or in the diene rubber (A), and have an average particle size of from 0.001 to 100 µm. Patent Document 3 discloses a rubber composition and a pneumatic tire using the same. The rubber composition contains a diene rubber (A) and a microparticle (B), a vinyl group content of the diene rubber (A) being from 5 to 35 mass %, the microparticle (B) being a mercapto group-containing organic microparticle in which a crosslinkable oligomer or polymer (b1) is crosslinked, an average particle size of the microparticle (B) being from 1 to 200 µm, and a content of the microparticle (B) being from 1 to 55 parts by mass per 100 parts by mass of the diene rubber (A). Citation List Patent Literature Patent Document 1: JP 5949026 BPatent Document 2: EP 3 272 803 A1Patent Document 3: US 2018/207984 A1 Summary of Invention Technical Problem In such circumstances, when the inventors of the present invention prepared particles using Patent Document 1 as a reference and evaluated a rubber composition containing the particles, it was found that, when, for example, a tire is formed from the rubber composition, further enhancement of fuel economy performance and tensile properties is desirable. Furthermore, it was also found that further enhancement of processability of the rubber composition is desirable. In addition, it was also found that enhancement of performance on ice is preferred. In light of the circumstances described above, an object of the present invention is to provide a particle dispersion exhibiting excellent processability, fuel economy performance, tensile properties, and performance on ice when used in a rubber composition, a method of producing the same, a rubber composition containing the particle dispersion, and a pneumatic tire produced by using the rubber composition. Solution to Problem As a result of diligent research to solve the problems described above, the inventors of the present invention found that, in a particle dispersion, by dispersing particles surface-modified with a hydrocarbon group having from 3 to 30 carbons and formed from a polymer that is not a diene polymer, in a diene polymer having a number average molecular weight from 1000 to 100000, and by bonding the hydrocarbon group to the polymer that is not a diene polymer through a urea bond or a urethane bond, effects such as excellent processability can be achieved when the particle dispersion is used for a rubber composition. Furthermore, the inventors of the present invention found a method of producing a particle dispersion, the method producing the particle dispersion described above and including: micelle forming of obtaining a micelle dispersion containing a micelle of a polymer, the polymer not being a diene polymer and containing an isocyanate group, by dispersing the polymer in a diene polymer having a number average molecular weight from 1000 to 100000 in the presence of a surfactant; andsurface-modifying of modifying a surface of the micelle with a hydrocarbon group having from 3 to 30 carbons by adding a compound containing the hydrocarbon group, and a hydroxy group, an amino group, or an imino group in the micelle dispersion, and allowing the isocyanate group contained in the micelle and the compound to react. Furthermore, the present inventors found that the desired effects can be achieved by a particle dispersion containing particles formed from a polymer that are dispersed in a diene