WO2011024268A1 - Run-flat tire - Google Patents

Run-flat tire Download PDF

Info

Publication number
WO2011024268A1
WO2011024268A1 PCT/JP2009/064878 JP2009064878W WO2011024268A1 WO 2011024268 A1 WO2011024268 A1 WO 2011024268A1 JP 2009064878 W JP2009064878 W JP 2009064878W WO 2011024268 A1 WO2011024268 A1 WO 2011024268A1
Authority
WO
WIPO (PCT)
Prior art keywords
rubber
run
molecular weight
flat tire
conjugated diene
Prior art date
Application number
PCT/JP2009/064878
Other languages
French (fr)
Japanese (ja)
Inventor
成晃 松尾
孝二 真崎
文徳 太田
Original Assignee
株式会社ブリヂストン
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 株式会社ブリヂストン filed Critical 株式会社ブリヂストン
Priority to PCT/JP2009/064878 priority Critical patent/WO2011024268A1/en
Publication of WO2011024268A1 publication Critical patent/WO2011024268A1/en

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L7/00—Compositions of natural rubber
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
    • C08L9/06—Copolymers with styrene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
    • B60C2001/0033—Compositions of the sidewall inserts, e.g. for runflat

Definitions

  • the present invention relates to a run-flat tire, particularly a run-flat tire having low run-flat tires and high run-flat durability.
  • a side reinforcing rubber layer with a crescent-shaped cross section is arranged on the sidewall of the tire as a so-called run-flat tire that can safely travel a certain distance even when the internal pressure of the tire is reduced by puncture or the like
  • a side-reinforcing type run-flat tire with improved sidewall rigidity is known.
  • the deformation of the side reinforcing rubber layer increases as the deformation of the sidewall portion of the tire increases.
  • the rubber component itself in the side reinforcing rubber layer is cut or crosslinked between the rubber components formed by vulcanization. The part may be cut.
  • the elastic modulus of the side reinforcing rubber layer decreases, the deflection of the tire further increases, the heat generation of the side wall portion proceeds, and finally the side reinforcing rubber layer exceeds its failure limit, and the tire is compared. There is a risk of failure at an early stage.
  • the elastic modulus of the side reinforcing rubber layer can be increased by changing the composition of the rubber composition applied to the side reinforcing rubber layer of the tire, or the loss of the side reinforcing rubber layer can be increased.
  • a technique for reducing the tangent (tan ⁇ ) and suppressing the heat generation of the side reinforcing rubber layer itself is known (see, for example, Patent Document 1).
  • an object of the present invention is to provide a run flat tire that solves the above-described problems of the prior art, has a small heat generation of the tire during run flat running, and has high run flat durability.
  • the present inventors have found that at least one of the bead filler and the side reinforcing rubber layer is a conjugated diene polymer having a low weight average molecular weight with respect to a rubber component having a specific composition. It was found that by using the rubber composition formed by blending the above, heat generation in the tire during run flat running is suppressed, and the run flat durability of the tire can be greatly improved, and the present invention has been completed.
  • the first run flat tire of the present invention is a run flat tire including a sidewall portion, a tread, a carcass, a bead core, and a bead filler.
  • the entire monomer unit constituting the bead filler having a weight average molecular weight in terms of polystyrene measured by gel permeation chromatography of 10,000 to 200,000 for the rubber component (A) containing at least natural rubber and / or polyisoprene rubber.
  • a rubber composition obtained by blending a low molecular weight conjugated diene polymer (B) having an aromatic vinyl compound content of less than 5% by mass is used.
  • the second run flat tire of the present invention is a run flat tire provided with a sidewall portion, a tread, a carcass and a side reinforcing rubber layer.
  • a monomer unit comprising a rubber component (A) containing at least natural rubber and / or polyisoprene rubber in the side reinforcing rubber layer and having a polystyrene-reduced weight average molecular weight of 10,000 to 200,000 as measured by gel permeation chromatography
  • a rubber composition obtained by blending a low molecular weight conjugated diene polymer (B) having an aromatic vinyl compound content of less than 5% by mass is used.
  • the third run flat tire of the present invention is a run flat tire including a sidewall portion, a tread, a carcass, a bead core, a bead filler, and a side reinforcing rubber layer.
  • the bead filler and the side reinforcing rubber layer are composed of a rubber component (A) containing at least natural rubber and / or polyisoprene rubber and having a polystyrene equivalent weight average molecular weight of 10,000 to 200,000 measured by gel permeation chromatography.
  • a rubber composition comprising a low molecular weight conjugated diene polymer (B) in which the ratio of the aromatic vinyl compound in the whole monomer unit is less than 5% by mass is used.
  • the rubber component (A) is at least one selected from the group consisting of natural rubber, polyisoprene rubber, styrene-butadiene copolymer rubber, polybutadiene rubber, and isobutylene isoprene rubber. Consists of.
  • the low molecular weight conjugated diene polymer (B) has a vinyl bond content of the conjugated diene compound portion of 40% or more.
  • the content of the low molecular weight conjugated diene polymer (B) is preferably 1 to 60 parts by mass with respect to 100 parts by mass of the rubber component (A).
  • the low molecular weight conjugated diene polymer (B) is polybutadiene.
  • the rubber composition further contains carbon black and / or silica.
  • the rubber composition further contains 3 to 10 parts by mass of sulfur with respect to 100 parts by mass of the rubber component (A).
  • At least one of the bead filler and the side reinforcing rubber layer is a rubber composition comprising a rubber component having a specific weight average molecular weight and composition and a conjugated diene polymer having a low weight average molecular weight.
  • FIG. 1 is a cross-sectional view of an embodiment of a run flat tire of the present invention.
  • the tire shown in FIG. 1 has a pair of left and right bead portions 1 and a pair of sidewall portions 2, and a tread 3 connected to both sidewall portions 2, and extends in a toroidal shape between the pair of bead portions 1.
  • a bead filler 7 disposed on the outer side in the tire radial direction of the embedded ring-shaped bead core 6 and a pair of side reinforcing rubber layers 8 disposed on the inner side of the carcass 4 of the sidewall portion 2 are provided.
  • the radial carcass 4 includes a folded carcass ply 4a having a folded portion wound around the bead core 6 from the inner side in the tire width direction toward the outer side in the radial direction, and the outer side of the folded carcass ply 4a. It consists of the arranged down carcass ply 4b.
  • the carcass structure and the number of plies are not limited thereto.
  • the bead filler 7 is disposed between the body portion and the folded portion of the folded carcass ply 4 a on the outer side in the tire radial direction of the bead core 6.
  • the shape of the side reinforcing rubber layer 8 in the illustrated example has a crescent-shaped cross section, the cross-sectional shape is not particularly limited as long as it has a side reinforcing function.
  • a belt 5 composed of two belt layers is disposed on the outer side in the tire radial direction of the crown portion of the radial carcass 4.
  • the two belt layers are laminated such that the cords constituting the belt layer intersect with each other across the equator plane, thereby constituting the belt 5.
  • the belt 5 in FIG. 1 is composed of two belt layers, but in the tire of the present invention, the number of belt layers constituting the belt 5 is not limited to this.
  • the run flat tire of the present invention may further include a belt reinforcing layer made of a rubberized layer of cords arranged substantially parallel to the tire circumferential direction on the outer side in the tire radial direction of the belt 5.
  • At least one of the bead filler 7 and the side reinforcing rubber layer 8 was measured by gel permeation chromatography with respect to a rubber component (A) containing at least natural rubber and / or polyisoprene rubber.
  • a rubber composition comprising a polystyrene-reduced weight average molecular weight of 10,000 to 200,000, and a low molecular weight conjugated diene polymer (B) in which the proportion of the aromatic vinyl compound in the total monomer units is less than 5% by mass. It is necessary to use things.
  • the illustrated tire includes both the bead filler 7 and the side reinforcing rubber layer 8, but the tire of the present invention includes a rubber composition containing the rubber component (A) and the low molecular weight conjugated diene polymer (B). What is necessary is just to provide the bead filler and / or side reinforcement rubber layer in which the thing was used.
  • a diene rubber containing a double bond in the main chain such as natural rubber or polyisoprene rubber as a rubber component (component A) is easily cut at a high temperature and has low heat resistance.
  • component A natural rubber or polyisoprene rubber as a rubber component
  • the low molecular weight conjugated diene polymer (B component) is blended in the rubber composition of the present invention, the cross-linked sulfur that has been cut by exposure to high temperature is reduced to the low molecular weight conjugated diene polymer (B component). There is an effect such as forming re-crosslinking with allylic carbon existing in the side chain.
  • the three-dimensional network structure can be maintained by recrosslinking of the low molecular weight conjugated diene polymer (component B) and the crosslinked sulfur, and the heat resistance of the rubber composition is improved.
  • a rubber composition in which the low molecular weight conjugated diene polymer (B) is blended with the rubber component (A) is used for at least one of the bead filler 7 and the side reinforcing rubber layer 8.
  • the gelation (high molecular weight) of the rubber component (A) and the low molecular weight conjugated diene polymer (B) in the high temperature region is promoted, and an increase in tire deflection during run flat running is suppressed.
  • Flat durability can be greatly improved.
  • the rubber component (A) used in the rubber composition is required to contain at least one of natural rubber (NR) and polyisoprene rubber (IR). If neither the natural rubber nor the polyisoprene rubber is contained in the rubber component (A), run-flat durability is lowered.
  • the rubber component (A) include natural rubber and polyisoprene rubber, styrene-butadiene copolymer rubber (SBR), polybutadiene rubber (BR), and isobutylene isoprene rubber (IIR).
  • the said rubber component (A) may be used individually by 1 type, and may blend and use 2 or more types.
  • the ratio of the styrene unit in the entire rubber component (A) is preferably less than 30% by mass, and 20% by mass. % Is more preferable, and it is more preferable that it is less than 15% by mass.
  • the rubber component (A) is excellent in compatibility with the low molecular weight conjugated diene polymer (B).
  • the rubber component (A) preferably has a polystyrene equivalent weight average molecular weight of more than 200,000 and not more than 3,000,000 as measured by gel permeation chromatography. If the polystyrene-equivalent weight average molecular weight is 200,000 or less, the unvulcanized viscosity is too low, the torque during kneading is not applied, and the kneading may be insufficient. On the other hand, when it exceeds 3,000,000, the unvulcanized viscosity is remarkably increased, and the workability during kneading and the molding workability tend to deteriorate. In addition, there is no restriction
  • the low molecular weight conjugated diene polymer (B) used in the rubber composition requires a polystyrene-reduced weight average molecular weight measured by gel permeation chromatography of 10,000 to 200,000, preferably 30,000 to 100,000. More preferably, it is 40,000 to 100,000.
  • weight average molecular weight in terms of polystyrene is less than 10,000, the effect of improving heat resistance cannot be obtained.
  • it exceeds 200,000 workability of the rubber composition is lowered.
  • the low molecular weight conjugated diene polymer (B) requires that the ratio of the aromatic vinyl compound unit to the whole of the monomer units constituting it is less than 5% by mass.
  • the low molecular weight conjugated diene polymer (B) may contain, for example, a styrene-butadiene copolymer. In this case, the proportion of styrene units in the entire polymer (B) is 5% by mass. If it becomes above, exothermic property will deteriorate and sufficient run-flat durability cannot be obtained.
  • the vinyl bond content of the conjugated diene compound portion is preferably 40% or more, more preferably 45% or more, and even more preferably 50% or more. . If the amount of vinyl bonds in the conjugated diene compound portion is 40% or more, a sufficient effect of improving heat resistance can be obtained. On the other hand, if the vinyl bond content in the conjugated diene compound portion is less than 40%, it is difficult to ensure the heat resistance of the rubber composition.
  • the low molecular weight conjugated diene polymer (B) is preferably a homopolymer of a conjugated diene compound or a copolymer of an aromatic vinyl compound and a conjugated diene compound.
  • conjugated diene compounds as monomers include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 2-phenyl-1,3-butadiene, and 1,3-hexadiene. Among these, 1,3-butadiene is preferable.
  • examples of the aromatic vinyl compound as a monomer include styrene, p-methylstyrene, m-methylstyrene, p-tert-butylstyrene, ⁇ -methylstyrene, chloromethylstyrene, vinyltoluene and the like. Therefore, polybutadiene is particularly preferable as the low molecular weight conjugated diene polymer (B).
  • these monomers may be used independently and may be used in combination of 2 or more type.
  • the low molecular weight conjugated diene polymer (B) is not particularly limited, and for example, a conjugated diene compound that is a monomer alone or a monomer in a hydrocarbon solvent inert to the polymerization reaction. It can be obtained by polymerizing a mixture of an aromatic vinyl compound and a conjugated diene compound.
  • the polymerization initiator used for the synthesis of the polymer (B) is preferably an alkali metal compound, more preferably a lithium compound, and still more preferably hydrocarbyl lithium and a lithium amide compound.
  • a lithium compound is used as the polymerization initiator, the aromatic vinyl compound and the conjugated diene compound are polymerized by anionic polymerization.
  • hydrocarbyl lithium is used as the polymerization initiator, a polymer having a hydrocarbyl group at the polymerization initiation terminal and the other terminal being a polymerization active site is obtained.
  • a lithium amide compound when used as a polymerization initiator, a polymer having a nitrogen-containing functional group at the polymerization initiation terminal and a polymerization active site at the other terminal is obtained, and the polymer is modified with a modifier. It can be used as a low molecular weight conjugated diene polymer (B) having at least one functional group.
  • the amount of the polymerization initiator used is preferably in the range of 0.2 to 20 mmol per 100 g of monomer.
  • hydrocarbyl lithium examples include ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, tert-octyl lithium, n-decyl lithium, phenyl lithium, 2-naphthyl lithium, and 2-butyl-phenyl.
  • Examples include lithium, 4-phenyl-butyllithium, cyclohexyllithium, cyclopentyllithium, reaction products of diisopropenylbenzene and butyllithium, and among these, ethyllithium, n-propyllithium, isopropyllithium, n-butyl Alkyl lithium such as lithium, sec-butyl lithium, tert-octyl lithium and n-decyl lithium is preferable, and n-butyl lithium is particularly preferable.
  • the method for producing a conjugated diene polymer using the polymerization initiator is not particularly limited as described above.
  • the monomer is polymerized in a hydrocarbon solvent inert to the polymerization reaction.
  • the polymer (B) can be produced.
  • hydrocarbon solvents inert to the polymerization reaction include propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane, propene, 1-butene, isobutene, trans-2-butene, cis -2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, benzene, toluene, xylene, ethylbenzene and the like. These may be used alone or in combination of two or more.
  • the above polymerization reaction may be carried out in the presence of a randomizer.
  • the randomizer can control the microstructure of the conjugated diene compound portion of the polymer. More specifically, the randomizer can control the vinyl bond amount of the conjugated diene compound portion of the polymer, It has effects such as randomizing diene compound units and aromatic vinyl compound units.
  • randomizer examples include dimethoxybenzene, tetrahydrofuran, dimethoxyethane, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, bistetrahydrofurylpropane, triethylamine, pyridine, N-methylmorpholine, N, N, N ′, N′-tetramethylethylenediamine, 1 , 2-dipiperidinoethane, potassium-t-amylate, potassium-t-butoxide, sodium-t-amylate and the like.
  • the amount of these randomizers used is preferably in the range of 0.1 to 100 molar equivalents per mole of polymerization initiator.
  • the anionic polymerization is preferably carried out by solution polymerization, and the concentration of the monomer in the polymerization reaction solution is preferably in the range of 5 to 50% by mass, and more preferably in the range of 10 to 30% by mass.
  • the content of the aromatic vinyl compound in the monomer mixture may be appropriately selected according to the amount of the aromatic vinyl compound in the target copolymer. it can.
  • the polymerization mode is not particularly limited, and may be batch type or continuous type.
  • the polymerization temperature for the anionic polymerization is preferably in the range of 0 to 150 ° C, more preferably in the range of 20 to 130 ° C.
  • the polymerization can be carried out under a generated pressure, but it is usually preferred to carry out the polymerization under a pressure sufficient to keep the monomer used in a substantially liquid phase.
  • the modifier used is preferably a nitrogen-containing compound, a silicon-containing compound or a tin-containing compound.
  • a nitrogen-containing functional group, a silicon-containing functional group, or a tin-containing functional group can be introduced by a modification reaction.
  • the modification reaction of the polymerization active site by the modifier is preferably performed by a solution reaction, and the solution may contain a monomer used at the time of polymerization.
  • the reaction mode of the modification reaction is not particularly limited, and may be a batch type or a continuous type.
  • the reaction temperature of the modification reaction is not particularly limited as long as the reaction proceeds, and the reaction temperature of the polymerization reaction may be employed as it is.
  • the amount of the modifying agent used is preferably in the range of 0.25 to 3.0 mol, more preferably in the range of 0.5 to 1.5 mol, with respect to 1 mol of the polymerization initiator used for producing the polymer.
  • the reaction solution containing the polymer (B) is dried to separate the polymer (B), and then the obtained polymer (B) is used as the rubber component.
  • the reaction solution containing the polymer (B) may be blended with the rubber cement of the rubber component (A) in a solution state and then dried to obtain the rubber component (A) and the polymer. You may obtain the mixture of (B).
  • the content of the low molecular weight conjugated diene polymer (B) is 1 to 60 parts by mass with respect to 100 parts by mass of the rubber component (A). preferable.
  • the content of the low molecular weight conjugated diene polymer (B) is less than 1 part by mass, the effect of imparting workability to the rubber composition is thin, and when it exceeds 60 parts by mass, the fracture characteristics of the vulcanized rubber are deteriorated. Tend.
  • a vulcanizing agent such as sulfur can be used for crosslinking the rubber component (A) and the low molecular weight conjugated diene polymer (B) to form a three-dimensional network structure.
  • the low molecular weight conjugated diene polymer (B) is difficult to be cross-linked because of its low molecular weight, and as a result, the flow of the polymer (B) that does not form cross-linkage may increase the tan ⁇ of the rubber composition. is there. Therefore, the rubber composition preferably contains 3 to 10 parts by mass of sulfur with respect to 100 parts by mass of the rubber component (A).
  • the sulfur content is within the above specified range, even if a conjugated diene polymer (B) having a low molecular weight is used, the conjugated diene portion of the rubber component (A) is incorporated into the three-dimensional network structure without any problem.
  • the unvulcanized viscosity can be effectively lowered without impairing the low loss performance.
  • the sulfur content is less than 3 parts by mass, the sulfur cannot be involved in the three-dimensional network structure, loss increases, and run-flat durability tends to decrease.
  • the sulfur content exceeds 10 parts by mass, re-crosslinking during heat aging is promoted, the heat aging property of the rubber is deteriorated, and the run-flat durability tends to decrease due to running deterioration.
  • the rubber composition preferably further contains a filler.
  • the filler include carbon black and silica.
  • carbon black those of FEF, SRF, HAF, ISAF, and SAF grade are preferable, and those of HAF, ISAF, and SAF grade are more preferable.
  • silica wet silica and dry silica are preferable, and wet silica is more preferable.
  • these fillers may be used alone or in combination of two or more.
  • the filler content is preferably 30 to 90 parts by mass with respect to 100 parts by mass of the rubber component (A). When the content of the filler is less than 30 parts by mass, the fracture characteristics and wear resistance of the vulcanized rubber are not sufficient, while when it exceeds 90 parts by mass, the workability tends to deteriorate.
  • the rubber composition may further contain a softening agent.
  • the softening agent include process oils such as paraffin oil, naphthenic oil, and aroma oil.
  • Aromatic oil is preferable from the viewpoint of fracture characteristics and wear resistance, and from the viewpoint of low heat buildup and low temperature characteristics.
  • the blending amount of the softening agent is not particularly limited, but the total blending amount of the low molecular weight conjugated diene polymer (B) and the softening agent is 1 with respect to 100 parts by mass of the rubber component (A). It is preferable to blend so as to be ⁇ 80 parts by mass. When the total amount of the low molecular weight conjugated diene polymer (B) and the softening agent exceeds 80 parts by mass, the fracture characteristics of the vulcanized rubber tend to deteriorate.
  • the rubber composition contains a compounding agent commonly used in the rubber industry, such as an anti-aging agent.
  • a silane coupling agent, a vulcanization accelerator, a vulcanization acceleration aid, a vulcanizing agent, and the like can be appropriately selected and blended within a range that does not impair the object of the present invention.
  • these compounding agents commercially available products can be suitably used.
  • the rubber composition is prepared by blending the rubber component (A) with the low molecular weight conjugated diene polymer (B) and various compounding agents appropriately selected as necessary, kneading, heating, extruding, and the like. Can be manufactured.
  • a rubber composition containing the rubber component (A) and the low molecular weight conjugated diene polymer (B) is applied to at least one of the bead filler 7 and the side reinforcing rubber layer 8. It can be produced by forming a green tire and vulcanizing the green tire according to a conventional method.
  • the gas filled in the tire may be normal or air with a changed oxygen partial pressure, or an inert gas such as nitrogen.
  • BHT 2,6-di-t-butyl-p-cresol
  • BHT 2,6-di-t-butyl-p-cresol
  • the weight average molecular weight (Mw) and microstructure of the polymers (A-1) and (B-1) to (B-7) produced as described above were measured by the following methods. The results are shown in Table 1.
  • Weight average molecular weight (Mw) Gel permeation chromatography [GPC: Tosoh HLC-8020, column: Tosoh GMH-XL (two in series), detector: differential refractometer (RI)], based on monodisperse polystyrene, The weight average molecular weight (Mw) in terms of polystyrene was determined.
  • microstructure of the polymer was determined by an infrared method (Morero method).
  • Examples 1 to 5 and Comparative Examples 1 to 5 A rubber composition having a compounding formulation shown in Table 2 was prepared, and the rubber composition was used for both the bead filler 7 and the side reinforcing rubber layer 8 to have the structure shown in FIG. 1 and have a size of 245 / 40R18. A flat tire was manufactured.
  • the low molecular weight conjugated diene polymer (B) has a polystyrene-equivalent weight average molecular weight outside the range of 10,000 to 200,000, and the effect of improving run-flat durability is not sufficiently obtained.
  • the ratio of the styrene unit of the low molecular weight conjugated diene polymer (B) is too high, the effect of improving the run flat durability cannot be sufficiently obtained.
  • rubber component (A) does not contain natural rubber and / or polyisoprene rubber, it turns out that run flat durability deteriorates.

Abstract

A run-flat tire which shows little heat generation in run-flat running and has a high run-flat durability.  More specifically, a run-flat tire comprising a pair of bead parts (1), in each of which a bead core (6) is embedded and a bead filler (7) is located outside of the same in the tire radial direction, and a pair of side walls (2) which are respectively provided with a pair of side reinforcing rubber layers (8), characterized in that, in at least one of the bead filler (7) and the side reinforcing rubber layers (8), a rubber composition comprising a rubber component (A) at least containing a natural rubber and/or a polyisoprene rubber and a low-molecular weight conjugated diene-based polymer (B) having a weight-average molecular weight in terms of polystyrene of 10,000 to 200,000 and containing an aromatic vinyl compound in an amount of less than 5 mass % relative to the total constituting monomers thereof is used.

Description

ランフラットタイヤRun flat tire
　本発明は、ランフラットタイヤ、特にランフラット走行時のタイヤの発熱が小さく、高いランフラット耐久性を有するランフラットタイヤに関するものである。 The present invention relates to a run-flat tire, particularly a run-flat tire having low run-flat tires and high run-flat durability.
　従来、パンク等によりタイヤの内圧が低下した状態でも、ある程度の距離を安全に走行することが可能なタイヤ、所謂ランフラットタイヤとして、タイヤのサイドウォール部に断面三日月状のサイド補強ゴム層を配置して、サイドウォール部の剛性を向上させた、サイド補強タイプのランフラットタイヤが知られている。しかしながら、タイヤの内圧が低下した状態での走行、所謂ランフラット走行においては、タイヤのサイドウォール部の変形が大きくなるにつれサイド補強ゴム層の変形も大きくなり、その結果、該サイド補強ゴム層の発熱が進んで、場合によっては200℃以上の高温に達することもあり、このような状態では、サイド補強ゴム層中のゴム成分自体が切断されたり、加硫により形成されたゴム成分間の架橋部が切断されたりすることがある。この場合、サイド補強ゴム層の弾性率が低下して、タイヤの撓みが更に大きくなってサイドウォール部の発熱が進み、遂には、サイド補強ゴム層がその破壊限界を超えてしまい、タイヤが比較的早期に故障に至る危険性がある。 Conventionally, a side reinforcing rubber layer with a crescent-shaped cross section is arranged on the sidewall of the tire as a so-called run-flat tire that can safely travel a certain distance even when the internal pressure of the tire is reduced by puncture or the like A side-reinforcing type run-flat tire with improved sidewall rigidity is known. However, in the so-called run-flat running in a state where the internal pressure of the tire is reduced, the deformation of the side reinforcing rubber layer increases as the deformation of the sidewall portion of the tire increases. In some cases, the rubber component itself in the side reinforcing rubber layer is cut or crosslinked between the rubber components formed by vulcanization. The part may be cut. In this case, the elastic modulus of the side reinforcing rubber layer decreases, the deflection of the tire further increases, the heat generation of the side wall portion proceeds, and finally the side reinforcing rubber layer exceeds its failure limit, and the tire is compared. There is a risk of failure at an early stage.
　このような故障に至るまでの時間を遅くする手段として、タイヤのサイド補強ゴム層に適用するゴム組成物の配合を変えることによってサイド補強ゴム層の弾性率を高めたり、サイド補強ゴム層の損失正接（tanδ）を低減して、サイド補強ゴム層自体の発熱を抑制する手法が知られている（例えば、特許文献１参照）。 As a means of delaying the time to failure, the elastic modulus of the side reinforcing rubber layer can be increased by changing the composition of the rubber composition applied to the side reinforcing rubber layer of the tire, or the loss of the side reinforcing rubber layer can be increased. A technique for reducing the tangent (tan δ) and suppressing the heat generation of the side reinforcing rubber layer itself is known (see, for example, Patent Document 1).
　しかしながら、従来のようなサイド補強ゴム層に適用するゴム組成物では、サイド補強ゴム層の発熱を十分に抑制できず、ランフラット走行において、一定以上の耐久距離を確保するためには、サイド補強ゴム層やビードフィラーを増量しているのが現状である。 However, in the conventional rubber composition applied to the side reinforcing rubber layer, the heat generation of the side reinforcing rubber layer cannot be sufficiently suppressed. At present, the amount of rubber layer and bead filler is increased.
特開２００２－１０３９１１号公報JP 2002-103911 A
　そこで、本発明の目的は、上記従来技術の問題を解決し、ランフラット走行時のタイヤの発熱が小さく、高いランフラット耐久性を有するランフラットタイヤを提供することにある。 Accordingly, an object of the present invention is to provide a run flat tire that solves the above-described problems of the prior art, has a small heat generation of the tire during run flat running, and has high run flat durability.
　本発明者らは、上記目的を達成するために鋭意検討した結果、ビードフィラー及びサイド補強ゴム層の少なくとも一方に、特定の組成からなるゴム成分に対し、重量平均分子量の低い共役ジエン系重合体を配合してなるゴム組成物を用いることで、ランフラット走行時のタイヤでの発熱が抑制され、タイヤのランフラット耐久性を大幅に改善できることを見出し、本発明を完成させるに至った。 As a result of intensive studies to achieve the above object, the present inventors have found that at least one of the bead filler and the side reinforcing rubber layer is a conjugated diene polymer having a low weight average molecular weight with respect to a rubber component having a specific composition. It was found that by using the rubber composition formed by blending the above, heat generation in the tire during run flat running is suppressed, and the run flat durability of the tire can be greatly improved, and the present invention has been completed.
　即ち、本発明の第１のランフラットタイヤは、サイドウォール部、トレッド、カーカス、ビードコア及びビードフィラーを備えたランフラットタイヤにおいて、
　前記ビードフィラーに、少なくとも天然ゴム及び／又はポリイソプレンゴムを含むゴム成分（Ａ）に対し、ゲル浸透クロマトグラフィーで測定したポリスチレン換算重量平均分子量が10,000～200,000で、構成する単量体単位の全体に占める芳香族ビニル化合物の割合が5質量％未満の低分子量共役ジエン系重合体（Ｂ）を配合してなるゴム組成物を用いたことを特徴とする。 That is, the first run flat tire of the present invention is a run flat tire including a sidewall portion, a tread, a carcass, a bead core, and a bead filler.
The entire monomer unit constituting the bead filler having a weight average molecular weight in terms of polystyrene measured by gel permeation chromatography of 10,000 to 200,000 for the rubber component (A) containing at least natural rubber and / or polyisoprene rubber. A rubber composition obtained by blending a low molecular weight conjugated diene polymer (B) having an aromatic vinyl compound content of less than 5% by mass is used.
　また、本発明の第２のランフラットタイヤは、サイドウォール部、トレッド、カーカス及びサイド補強ゴム層を備えたランフラットタイヤにおいて、
　前記サイド補強ゴム層に、少なくとも天然ゴム及び／又はポリイソプレンゴムを含むゴム成分（Ａ）に対し、ゲル浸透クロマトグラフィーで測定したポリスチレン換算重量平均分子量が10,000～200,000で、構成する単量体単位の全体に占める芳香族ビニル化合物の割合が5質量％未満の低分子量共役ジエン系重合体（Ｂ）を配合してなるゴム組成物を用いたことを特徴とする。 The second run flat tire of the present invention is a run flat tire provided with a sidewall portion, a tread, a carcass and a side reinforcing rubber layer.
A monomer unit comprising a rubber component (A) containing at least natural rubber and / or polyisoprene rubber in the side reinforcing rubber layer and having a polystyrene-reduced weight average molecular weight of 10,000 to 200,000 as measured by gel permeation chromatography A rubber composition obtained by blending a low molecular weight conjugated diene polymer (B) having an aromatic vinyl compound content of less than 5% by mass is used.
　更に、本発明の第３のランフラットタイヤは、サイドウォール部、トレッド、カーカス、ビードコア、ビードフィラー及びサイド補強ゴム層を備えたランフラットタイヤにおいて、
　前記ビードフィラー及び前記サイド補強ゴム層に、少なくとも天然ゴム及び／又はポリイソプレンゴムを含むゴム成分（Ａ）に対し、ゲル浸透クロマトグラフィーで測定したポリスチレン換算重量平均分子量が10,000～200,000で、構成する単量体単位の全体に占める芳香族ビニル化合物の割合が5質量％未満の低分子量共役ジエン系重合体（Ｂ）を配合してなるゴム組成物を用いたことを特徴とする。 Furthermore, the third run flat tire of the present invention is a run flat tire including a sidewall portion, a tread, a carcass, a bead core, a bead filler, and a side reinforcing rubber layer.
The bead filler and the side reinforcing rubber layer are composed of a rubber component (A) containing at least natural rubber and / or polyisoprene rubber and having a polystyrene equivalent weight average molecular weight of 10,000 to 200,000 measured by gel permeation chromatography. A rubber composition comprising a low molecular weight conjugated diene polymer (B) in which the ratio of the aromatic vinyl compound in the whole monomer unit is less than 5% by mass is used.
　本発明のランフラットタイヤの好適例においては、前記ゴム成分（Ａ）が、天然ゴム、ポリイソプレンゴム、スチレン－ブタジエン共重合体ゴム、ポリブタジエンゴム及びイソブチレンイソプレンゴムからなる群から選択される少なくとも一種からなる。 In a preferred embodiment of the run flat tire of the present invention, the rubber component (A) is at least one selected from the group consisting of natural rubber, polyisoprene rubber, styrene-butadiene copolymer rubber, polybutadiene rubber, and isobutylene isoprene rubber. Consists of.
　本発明のランフラットタイヤの他の好適例において、前記低分子量共役ジエン系重合体（Ｂ）は、共役ジエン化合物部分のビニル結合量が40％以上である。 In another preferred embodiment of the run-flat tire of the present invention, the low molecular weight conjugated diene polymer (B) has a vinyl bond content of the conjugated diene compound portion of 40% or more.
　本発明のランフラットタイヤは、前記低分子量共役ジエン系重合体（Ｂ）の含有量が、上記ゴム成分（Ａ）100質量部に対し1～60質量部であることが好ましい。 In the run-flat tire of the present invention, the content of the low molecular weight conjugated diene polymer (B) is preferably 1 to 60 parts by mass with respect to 100 parts by mass of the rubber component (A).
　本発明のランフラットタイヤの他の好適例においては、前記低分子量共役ジエン系重合体（Ｂ）がポリブタジエンである。 In another preferred embodiment of the run flat tire of the present invention, the low molecular weight conjugated diene polymer (B) is polybutadiene.
　本発明のランフラットタイヤの他の好適例においては、前記ゴム組成物が、更にカーボンブラック及び／又はシリカを含有する。 In another preferred embodiment of the run flat tire of the present invention, the rubber composition further contains carbon black and / or silica.
　本発明のランフラットタイヤの他の好適例においては、前記ゴム組成物が、更に硫黄をゴム成分（Ａ）100質量部に対し3～10質量部含有する。 In another preferred embodiment of the run flat tire of the present invention, the rubber composition further contains 3 to 10 parts by mass of sulfur with respect to 100 parts by mass of the rubber component (A).
　本発明によれば、ビードフィラー及びサイド補強ゴム層の少なくとも一方に、特定の重量平均分子量と組成からなるゴム成分に対し、重量平均分子量の低い共役ジエン系重合体を配合してなるゴム組成物を用いることで、ランフラット走行時のタイヤの発熱が小さく、高いランフラット耐久性を有するランフラットタイヤを提供することことができる。 According to the present invention, at least one of the bead filler and the side reinforcing rubber layer is a rubber composition comprising a rubber component having a specific weight average molecular weight and composition and a conjugated diene polymer having a low weight average molecular weight. By using this, it is possible to provide a run-flat tire that has low heat generation during run-flat running and high run-flat durability.
本発明のランフラットタイヤの一実施形態の断面図である。It is sectional drawing of one Embodiment of the run flat tire of this invention.
　以下に、図を参照しながら本発明を詳細に説明する。図１は、本発明のランフラットタイヤの一実施形態の断面図である。図１に示すタイヤは、左右一対のビード部１及び一対のサイドウォール部２と、両サイドウォール部２に連なるトレッド３とを有し、前記一対のビード部１間にトロイド状に延在して、これら各部１，２，３を補強するラジアルカーカス４と、該カーカス４のクラウン部のタイヤ半径方向外側に配置された２枚のベルト層からなるベルト５と、前記ビード部１内に夫々埋設したリング状のビードコア６のタイヤ半径方向外側に配置したビードフィラー７と、前記サイドウォール部２の前記カーカス４の内側に配置した一対のサイド補強ゴム層８とを備える。 Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of an embodiment of a run flat tire of the present invention. The tire shown in FIG. 1 has a pair of left and right bead portions 1 and a pair of sidewall portions 2, and a tread 3 connected to both sidewall portions 2, and extends in a toroidal shape between the pair of bead portions 1. A radial carcass 4 that reinforces each of these parts 1, 2, 3, a belt 5 composed of two belt layers arranged on the outer side in the tire radial direction of the crown part of the carcass 4, and the bead part 1, respectively. A bead filler 7 disposed on the outer side in the tire radial direction of the embedded ring-shaped bead core 6 and a pair of side reinforcing rubber layers 8 disposed on the inner side of the carcass 4 of the sidewall portion 2 are provided.
　図示例のタイヤにおいて、ラジアルカーカス４は、ビードコア６の周りでタイヤ幅方向内側から外側に向けて半径方向外方に巻上げた折り返し部を有する折り返しカーカスプライ４ａと、該折り返しカーカスプライ４ａの外側に配置されたダウンカーカスプライ４ｂとからなる。なお、本発明のタイヤにおいて、カーカスの構造及びプライ数は、これに限られるものではない。更に、ビードフィラー７は、ビードコア６のタイヤ半径方向外側の折り返しカーカスプライ４ａの本体部と折り返し部との間に配置されている。なお、図示例のサイド補強ゴム層８の形状は、断面三日月状であるが、その断面形状はサイド補強の機能を有するものであれば特に限定されない。 In the illustrated tire, the radial carcass 4 includes a folded carcass ply 4a having a folded portion wound around the bead core 6 from the inner side in the tire width direction toward the outer side in the radial direction, and the outer side of the folded carcass ply 4a. It consists of the arranged down carcass ply 4b. In the tire of the present invention, the carcass structure and the number of plies are not limited thereto. Further, the bead filler 7 is disposed between the body portion and the folded portion of the folded carcass ply 4 a on the outer side in the tire radial direction of the bead core 6. In addition, although the shape of the side reinforcing rubber layer 8 in the illustrated example has a crescent-shaped cross section, the cross-sectional shape is not particularly limited as long as it has a side reinforcing function.
　また、図１に示すタイヤにおいては、上記ラジアルカーカス４のクラウン部のタイヤ半径方向外側に二枚のベルト層からなるベルト５が配置されており、該ベルト層は、通常、タイヤ赤道面に対して傾斜して延びるコードのゴム引き層からなり、２枚のベルト層は、該ベルト層を構成するコードが互いに赤道面を挟んで交差するように積層されてベルト５を構成する。なお、図１中のベルト５は、二枚のベルト層からなるが、本発明のタイヤにおいては、ベルト５を構成するベルト層の枚数はこれに限られるものではない。また、本発明のランフラットタイヤは、ベルト５のタイヤ半径方向外側に、タイヤ周方向に対し実質的に平行に配列したコードのゴム引き層からなるベルト補強層を備えてもよい。 In the tire shown in FIG. 1, a belt 5 composed of two belt layers is disposed on the outer side in the tire radial direction of the crown portion of the radial carcass 4. The two belt layers are laminated such that the cords constituting the belt layer intersect with each other across the equator plane, thereby constituting the belt 5. The belt 5 in FIG. 1 is composed of two belt layers, but in the tire of the present invention, the number of belt layers constituting the belt 5 is not limited to this. The run flat tire of the present invention may further include a belt reinforcing layer made of a rubberized layer of cords arranged substantially parallel to the tire circumferential direction on the outer side in the tire radial direction of the belt 5.
　本発明のランフラットタイヤにおいては、上記ビードフィラー７及びサイド補強ゴム層８の少なくとも一方に、少なくとも天然ゴム及び／又はポリイソプレンゴムを含むゴム成分（Ａ）に対し、ゲル浸透クロマトグラフィーで測定したポリスチレン換算重量平均分子量が10,000～200,000で、構成する単量体単位の全体に占める芳香族ビニル化合物の割合が5質量％未満の低分子量共役ジエン系重合体（Ｂ）を配合してなるゴム組成物を用いることを要する。なお、図示例のタイヤは、ビードフィラー７及びサイド補強ゴム層８の双方を備えるが、本発明のタイヤは、上記ゴム成分（Ａ）及び低分子量共役ジエン系重合体（Ｂ）を含むゴム組成物が用いられたビードフィラー及び／又はサイド補強ゴム層を備えていればよい。 In the run flat tire of the present invention, at least one of the bead filler 7 and the side reinforcing rubber layer 8 was measured by gel permeation chromatography with respect to a rubber component (A) containing at least natural rubber and / or polyisoprene rubber. A rubber composition comprising a polystyrene-reduced weight average molecular weight of 10,000 to 200,000, and a low molecular weight conjugated diene polymer (B) in which the proportion of the aromatic vinyl compound in the total monomer units is less than 5% by mass. It is necessary to use things. The illustrated tire includes both the bead filler 7 and the side reinforcing rubber layer 8, but the tire of the present invention includes a rubber composition containing the rubber component (A) and the low molecular weight conjugated diene polymer (B). What is necessary is just to provide the bead filler and / or side reinforcement rubber layer in which the thing was used.
　一般に、ゴム成分（Ａ成分）として天然ゴムやポリイソプレンゴム等の主鎖に二重結合を含むジエン系ゴムは、高温で切断され易く、耐熱性が低い。しかしながら、本発明のゴム組成物においては、低分子量共役ジエン系重合体（Ｂ成分）を配合しているため、高温にさらされ切断した架橋硫黄が、低分子量共役ジエン系重合体（Ｂ成分）の側鎖に存在するアリル位の炭素と再架橋を形成する等の効果がある。従って、低分子量共役ジエン系重合体（Ｂ成分）と架橋硫黄との再架橋により、三次元網目構造を維持することができ、ゴム組成物の耐熱性が向上する。このため、本発明のランフラットタイヤは、上記ゴム成分（Ａ）に上記低分子量共役ジエン系重合体（Ｂ）を配合したゴム組成物をビードフィラー７及びサイド補強ゴム層８の少なくとも一方に用いることで、ゴム成分（Ａ）及び低分子量共役ジエン系重合体（Ｂ）の高温領域でのゲル化（高分子量化）が促進され、ランフラット走行時のタイヤの撓みの増加を抑制し、ランフラット耐久性を大幅に向上できる。 Generally, a diene rubber containing a double bond in the main chain such as natural rubber or polyisoprene rubber as a rubber component (component A) is easily cut at a high temperature and has low heat resistance. However, since the low molecular weight conjugated diene polymer (B component) is blended in the rubber composition of the present invention, the cross-linked sulfur that has been cut by exposure to high temperature is reduced to the low molecular weight conjugated diene polymer (B component). There is an effect such as forming re-crosslinking with allylic carbon existing in the side chain. Therefore, the three-dimensional network structure can be maintained by recrosslinking of the low molecular weight conjugated diene polymer (component B) and the crosslinked sulfur, and the heat resistance of the rubber composition is improved. For this reason, in the run flat tire of the present invention, a rubber composition in which the low molecular weight conjugated diene polymer (B) is blended with the rubber component (A) is used for at least one of the bead filler 7 and the side reinforcing rubber layer 8. As a result, the gelation (high molecular weight) of the rubber component (A) and the low molecular weight conjugated diene polymer (B) in the high temperature region is promoted, and an increase in tire deflection during run flat running is suppressed. Flat durability can be greatly improved.
　上記ゴム組成物に用いるゴム成分（Ａ）は、天然ゴム（ＮＲ）及びポリイソプレンゴム（ＩＲ）の少なくとも一方を含むことを要する。該ゴム成分（Ａ）に天然ゴム及びポリイソプレンゴムをいずれも含んでいないと、ランフラット耐久性が低下する。また、上記ゴム成分（Ａ）としては、天然ゴム及びポリイソプレンゴムの他、スチレン－ブタジエン共重合体ゴム（ＳＢＲ）、ポリブタジエンゴム（ＢＲ）、イソブチレンイソプレンゴム（ＩＩＲ）等が挙げられる。なお、上記ゴム成分（Ａ）は、一種単独で用いてもよいし、二種以上をブレンドして用いてもよい。また、上記ゴム成分（Ａ）がスチレン－ブタジエン共重合体ゴムを含有する場合においては、ゴム成分（Ａ）の全体に占めるスチレン単位の割合が、30質量％未満であることが好ましく、20質量％未満であることが更に好ましく、15質量％未満であることが一層好ましい。ゴム成分（Ａ）の全体に占めるスチレン単位の割合が30質量％未満である場合、ゴム成分（Ａ）は、上記低分子量共役ジエン系重合体（Ｂ）との相溶性に優れる。 The rubber component (A) used in the rubber composition is required to contain at least one of natural rubber (NR) and polyisoprene rubber (IR). If neither the natural rubber nor the polyisoprene rubber is contained in the rubber component (A), run-flat durability is lowered. Examples of the rubber component (A) include natural rubber and polyisoprene rubber, styrene-butadiene copolymer rubber (SBR), polybutadiene rubber (BR), and isobutylene isoprene rubber (IIR). In addition, the said rubber component (A) may be used individually by 1 type, and may blend and use 2 or more types. In the case where the rubber component (A) contains a styrene-butadiene copolymer rubber, the ratio of the styrene unit in the entire rubber component (A) is preferably less than 30% by mass, and 20% by mass. % Is more preferable, and it is more preferable that it is less than 15% by mass. When the ratio of the styrene unit to the whole rubber component (A) is less than 30% by mass, the rubber component (A) is excellent in compatibility with the low molecular weight conjugated diene polymer (B).
　また、上記ゴム成分（Ａ）は、ゲル浸透クロマトグラフィーで測定したポリスチレン換算重量平均分子量が200,000を超えて且つ3,000,000以下であることが好ましい。該ポリスチレン換算重量平均分子量が200,000以下では、未加硫粘度が下がりすぎ、混練り時のトルクがかからず、練り不十分となる可能性が考えられる。一方、3,000,000を超えると、未加硫粘度が著しく上昇し、混練り時の作業性及び成型作業性が悪化する傾向がある。なお、上記ゴム成分（Ａ）を製造する方法としては、特に制限はなく、例えば、下記に説明する低分子量共役ジエン系重合体（Ｂ）の製造方法と同様のものが挙げられる。 The rubber component (A) preferably has a polystyrene equivalent weight average molecular weight of more than 200,000 and not more than 3,000,000 as measured by gel permeation chromatography. If the polystyrene-equivalent weight average molecular weight is 200,000 or less, the unvulcanized viscosity is too low, the torque during kneading is not applied, and the kneading may be insufficient. On the other hand, when it exceeds 3,000,000, the unvulcanized viscosity is remarkably increased, and the workability during kneading and the molding workability tend to deteriorate. In addition, there is no restriction | limiting in particular as a method of manufacturing the said rubber component (A), For example, the thing similar to the manufacturing method of the low molecular weight conjugated diene type polymer (B) demonstrated below is mentioned.
　上記ゴム組成物に用いる低分子量共役ジエン系重合体（Ｂ）は、ゲル浸透クロマトグラフィーで測定したポリスチレン換算重量平均分子量が10,000～200,000であることを要し、30,000～100,000であることが好ましく、40,000～100,000であることが更に好ましい。該ポリスチレン換算重量平均分子量が10,000未満では、耐熱性の向上効果が得られず、一方、200,000を超えると、ゴム組成物の作業性が低下する。 The low molecular weight conjugated diene polymer (B) used in the rubber composition requires a polystyrene-reduced weight average molecular weight measured by gel permeation chromatography of 10,000 to 200,000, preferably 30,000 to 100,000. More preferably, it is 40,000 to 100,000. When the weight average molecular weight in terms of polystyrene is less than 10,000, the effect of improving heat resistance cannot be obtained. On the other hand, when it exceeds 200,000, workability of the rubber composition is lowered.
　上記低分子量共役ジエン系重合体（Ｂ）は、構成する単量体単位の全体に占める芳香族ビニル化合物単位の割合が5質量％未満であることを要する。上記低分子量共役ジエン系重合体（Ｂ）は、例えば、スチレン－ブタジエン共重合体等を含む場合があり、この場合において、該重合体（Ｂ）の全体に占めるスチレン単位の割合が5質量％以上になると、発熱性が悪化し、十分なランフラット耐久性を得ることができない。 The low molecular weight conjugated diene polymer (B) requires that the ratio of the aromatic vinyl compound unit to the whole of the monomer units constituting it is less than 5% by mass. The low molecular weight conjugated diene polymer (B) may contain, for example, a styrene-butadiene copolymer. In this case, the proportion of styrene units in the entire polymer (B) is 5% by mass. If it becomes above, exothermic property will deteriorate and sufficient run-flat durability cannot be obtained.
　上記低分子量共役ジエン系重合体（Ｂ）は、共役ジエン化合物部分のビニル結合量が40％以上であることが好ましく、45％以上であることが更に好ましく、50％以上であることが一層好ましい。共役ジエン化合物部分のビニル結合量が40％以上であれば、十分な耐熱性の向上効果が得られる。一方、共役ジエン化合物部分のビニル結合量が40％未満では、ゴム組成物の耐熱性の確保が困難になる。 In the low molecular weight conjugated diene polymer (B), the vinyl bond content of the conjugated diene compound portion is preferably 40% or more, more preferably 45% or more, and even more preferably 50% or more. . If the amount of vinyl bonds in the conjugated diene compound portion is 40% or more, a sufficient effect of improving heat resistance can be obtained. On the other hand, if the vinyl bond content in the conjugated diene compound portion is less than 40%, it is difficult to ensure the heat resistance of the rubber composition.
　上記低分子量共役ジエン系重合体（Ｂ）としては、共役ジエン化合物の単独重合体、又は芳香族ビニル化合物と共役ジエン化合物との共重合体が好ましい。ここで、単量体としての共役ジエン化合物としては、１,３-ブタジエン、イソプレン、１,３-ペンタジエン、２,３-ジメチルブタジエン、２-フェニル-１,３-ブタジエン、１,３-ヘキサジエン等が挙げられ、これらの中でも、１,３-ブタジエンが好ましい。一方、単量体としての芳香族ビニル化合物としては、スチレン、ｐ-メチルスチレン、ｍ-メチルスチレン、ｐ-tert-ブチルスチレン、α-メチルスチレン、クロロメチルスチレン、ビニルトルエン等が挙げられる。従って、上記低分子量共役ジエン系重合体（Ｂ）としては、ポリブタジエンが特に好ましい。なお、これら単量体は、単独で用いてもよく、二種以上を組み合わせて用いてもよい。 The low molecular weight conjugated diene polymer (B) is preferably a homopolymer of a conjugated diene compound or a copolymer of an aromatic vinyl compound and a conjugated diene compound. Here, conjugated diene compounds as monomers include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 2-phenyl-1,3-butadiene, and 1,3-hexadiene. Among these, 1,3-butadiene is preferable. On the other hand, examples of the aromatic vinyl compound as a monomer include styrene, p-methylstyrene, m-methylstyrene, p-tert-butylstyrene, α-methylstyrene, chloromethylstyrene, vinyltoluene and the like. Therefore, polybutadiene is particularly preferable as the low molecular weight conjugated diene polymer (B). In addition, these monomers may be used independently and may be used in combination of 2 or more type.
　上記低分子量共役ジエン系重合体（Ｂ）は、特に制限されず、例えば、重合反応に不活性な炭化水素溶媒中で、単量体である共役ジエン化合物を単独で、又は単量体である芳香族ビニル化合物と共役ジエン化合物との混合物を重合して得ることができるが、該低分子量共役ジエン系重合体（Ｂ）の分子中に少なくとも一つの官能基を導入する場合においては、（１）単量体を重合開始剤を用いて重合させ、重合活性部位を有する重合体を生成させた後、該重合活性部位を各種変性剤で変性する方法や、（２）単量体を、官能基を有する重合開始剤、例えばＳｎ-Ｌｉ、Ｃ-Ｌｉ又はＮ-Ｌｉ結合を有する重合開始剤を用いて重合させる方法で得ることができる。 The low molecular weight conjugated diene polymer (B) is not particularly limited, and for example, a conjugated diene compound that is a monomer alone or a monomer in a hydrocarbon solvent inert to the polymerization reaction. It can be obtained by polymerizing a mixture of an aromatic vinyl compound and a conjugated diene compound. In the case of introducing at least one functional group into the molecule of the low molecular weight conjugated diene polymer (B), (1 A method of polymerizing a monomer using a polymerization initiator to form a polymer having a polymerization active site, and then modifying the polymerization active site with various modifiers; It can be obtained by a polymerization method using a polymerization initiator having a group, for example, a polymerization initiator having a Sn—Li, C—Li or N—Li bond.
　上記重合体（Ｂ）の合成に用いる重合開始剤としては、アルカリ金属化合物が好ましく、リチウム化合物が更に好ましく、ヒドロカルビルリチウム及びリチウムアミド化合物が一層好ましい。なお、重合開始剤としてリチウム化合物を用いた場合、芳香族ビニル化合物と共役ジエン化合物とは、アニオン重合で重合される。重合開始剤としてヒドロカルビルリチウムを用いる場合、重合開始末端にヒドロカルビル基を有し、他方の末端が重合活性部位である重合体が得られる。一方、重合開始剤としてリチウムアミド化合物を用いる場合、重合開始末端に窒素含有官能基を有し、他方の末端が重合活性部位である重合体が得られ、該重合体は、変性剤で変性することなく、少なくとも一つの官能基を有する低分子量共役ジエン系重合体（Ｂ）として用いることができる。なお、重合開始剤の使用量は、単量体100g当り0.2～20mmolの範囲が好ましい。 The polymerization initiator used for the synthesis of the polymer (B) is preferably an alkali metal compound, more preferably a lithium compound, and still more preferably hydrocarbyl lithium and a lithium amide compound. In addition, when a lithium compound is used as the polymerization initiator, the aromatic vinyl compound and the conjugated diene compound are polymerized by anionic polymerization. When hydrocarbyl lithium is used as the polymerization initiator, a polymer having a hydrocarbyl group at the polymerization initiation terminal and the other terminal being a polymerization active site is obtained. On the other hand, when a lithium amide compound is used as a polymerization initiator, a polymer having a nitrogen-containing functional group at the polymerization initiation terminal and a polymerization active site at the other terminal is obtained, and the polymer is modified with a modifier. It can be used as a low molecular weight conjugated diene polymer (B) having at least one functional group. The amount of the polymerization initiator used is preferably in the range of 0.2 to 20 mmol per 100 g of monomer.
　上記ヒドロカルビルリチウムとしては、エチルリチウム、ｎ-プロピルリチウム、イソプロピルリチウム、ｎ-ブチルリチウム、sec-ブチルリチウム、tert-オクチルリチウム、ｎ-デシルリチウム、フェニルリチウム、２-ナフチルリチウム、２-ブチル-フェニルリチウム、４-フェニル-ブチルリチウム、シクロヘキシルリチウム、シクロペンチルリチウム、ジイソプロペニルベンゼンとブチルリチウムとの反応生成物等が挙げられ、これらの中でも、エチルリチウム、ｎ-プロピルリチウム、イソプロピルリチウム、ｎ-ブチルリチウム、sec-ブチルリチウム、tert-オクチルリチウム、ｎ-デシルリチウム等のアルキルリチウムが好ましく、ｎ-ブチルリチウムが特に好ましい。 Examples of the hydrocarbyl lithium include ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, tert-octyl lithium, n-decyl lithium, phenyl lithium, 2-naphthyl lithium, and 2-butyl-phenyl. Examples include lithium, 4-phenyl-butyllithium, cyclohexyllithium, cyclopentyllithium, reaction products of diisopropenylbenzene and butyllithium, and among these, ethyllithium, n-propyllithium, isopropyllithium, n-butyl Alkyl lithium such as lithium, sec-butyl lithium, tert-octyl lithium and n-decyl lithium is preferable, and n-butyl lithium is particularly preferable.
　上記重合開始剤を用いて、共役ジエン系重合体を製造する方法としては、上述のとおり、特に制限はなく、例えば、重合反応に不活性な炭化水素溶媒中で、単量体を重合させることで該重合体（Ｂ）を製造することができる。ここで、重合反応に不活性な炭化水素溶媒としては、プロパン、ｎ-ブタン、イソブタン、ｎ-ペンタン、イソペンタン、ｎ-ヘキサン、シクロヘキサン、プロペン、１-ブテン、イソブテン、トランス-２-ブテン、シス-２-ブテン、１-ペンテン、２-ペンテン、１-ヘキセン、２-ヘキセン、ベンゼン、トルエン、キシレン、エチルベンゼン等が挙げられる。これらは単独で用いてもよく、二種以上を混合して用いてもよい。 The method for producing a conjugated diene polymer using the polymerization initiator is not particularly limited as described above. For example, the monomer is polymerized in a hydrocarbon solvent inert to the polymerization reaction. Thus, the polymer (B) can be produced. Here, hydrocarbon solvents inert to the polymerization reaction include propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, cyclohexane, propene, 1-butene, isobutene, trans-2-butene, cis -2-butene, 1-pentene, 2-pentene, 1-hexene, 2-hexene, benzene, toluene, xylene, ethylbenzene and the like. These may be used alone or in combination of two or more.
　上記重合反応は、ランダマイザーの存在下で実施してもよい。該ランダマイザーは、重合体の共役ジエン化合物部分のミクロ構造を制御することができ、より具体的には、重合体の共役ジエン化合物部分のビニル結合量を制御したり、共重合体中の共役ジエン化合物単位と芳香族ビニル化合物単位とをランダム化する等の作用を有する。上記ランダマイザーとしては、ジメトキシベンゼン、テトラヒドロフラン、ジメトキシエタン、ジエチレングリコールジブチルエーテル、ジエチレングリコールジメチルエーテル、ビステトラヒドロフリルプロパン、トリエチルアミン、ピリジン、Ｎ-メチルモルホリン、Ｎ,Ｎ,Ｎ',Ｎ'-テトラメチルエチレンジアミン、１,２-ジピペリジノエタン、カリウム-ｔ-アミレート、カリウム-ｔ-ブトキシド、ナトリウム-ｔ-アミレート等が挙げられる。これらランダマイザーの使用量は、重合開始剤1モル当り0.1～100モル当量の範囲が好ましい。 The above polymerization reaction may be carried out in the presence of a randomizer. The randomizer can control the microstructure of the conjugated diene compound portion of the polymer. More specifically, the randomizer can control the vinyl bond amount of the conjugated diene compound portion of the polymer, It has effects such as randomizing diene compound units and aromatic vinyl compound units. Examples of the randomizer include dimethoxybenzene, tetrahydrofuran, dimethoxyethane, diethylene glycol dibutyl ether, diethylene glycol dimethyl ether, bistetrahydrofurylpropane, triethylamine, pyridine, N-methylmorpholine, N, N, N ′, N′-tetramethylethylenediamine, 1 , 2-dipiperidinoethane, potassium-t-amylate, potassium-t-butoxide, sodium-t-amylate and the like. The amount of these randomizers used is preferably in the range of 0.1 to 100 molar equivalents per mole of polymerization initiator.
　上記アニオン重合は、溶液重合で実施することが好ましく、重合反応溶液中の上記単量体の濃度は、5～50質量％の範囲が好ましく、10～30質量％の範囲が更に好ましい。なお、共役ジエン化合物と芳香族ビニル化合物を併用する場合、単量体混合物中の芳香族ビニル化合物の含有率は、目的とする共重合体の芳香族ビニル化合物量に応じて適宜選択することができる。また、重合形式は特に限定されず、回分式でも連続式でもよい。 The anionic polymerization is preferably carried out by solution polymerization, and the concentration of the monomer in the polymerization reaction solution is preferably in the range of 5 to 50% by mass, and more preferably in the range of 10 to 30% by mass. When the conjugated diene compound and the aromatic vinyl compound are used in combination, the content of the aromatic vinyl compound in the monomer mixture may be appropriately selected according to the amount of the aromatic vinyl compound in the target copolymer. it can. Further, the polymerization mode is not particularly limited, and may be batch type or continuous type.
　上記アニオン重合の重合温度は、0～150℃の範囲が好ましく、20～130℃の範囲が更に好ましい。また、該重合は、発生圧力下で実施できるが、通常は、使用する単量体を実質的に液相に保つのに十分な圧力下で行うことが好ましい。ここで、重合反応を発生圧力より高い圧力下で実施する場合、反応系を不活性ガスで加圧することが好ましい。また、重合に使用する単量体、重合開始剤、溶媒等の原材料は、水、酸素、二酸化炭素、プロトン性化合物等の反応阻害物質を予め除去したものを用いることが好ましい。 The polymerization temperature for the anionic polymerization is preferably in the range of 0 to 150 ° C, more preferably in the range of 20 to 130 ° C. The polymerization can be carried out under a generated pressure, but it is usually preferred to carry out the polymerization under a pressure sufficient to keep the monomer used in a substantially liquid phase. Here, when the polymerization reaction is carried out under a pressure higher than the generated pressure, it is preferable to pressurize the reaction system with an inert gas. Moreover, it is preferable to use what removed reaction-inhibiting substances, such as water, oxygen, a carbon dioxide, and a protic compound, as raw materials, such as a monomer used for superposition | polymerization, a polymerization initiator, and a solvent.
　更に、上記重合活性部位を有する(共)重合体の重合活性部位を変性剤で変性するにあたって、使用する変性剤としては、窒素含有化合物、ケイ素含有化合物及びスズ含有化合物が好ましい。この場合、変性反応により、窒素含有官能基、ケイ素含有官能基又はスズ含有官能基を導入することができる。 Further, when the polymerization active site of the (co) polymer having the polymerization active site is modified with a modifier, the modifier used is preferably a nitrogen-containing compound, a silicon-containing compound or a tin-containing compound. In this case, a nitrogen-containing functional group, a silicon-containing functional group, or a tin-containing functional group can be introduced by a modification reaction.
　上記変性剤による重合活性部位の変性反応は、溶液反応で行うことが好ましく、該溶液中には、重合時に使用した単量体が含まれていてもよい。また、変性反応の反応形式は特に制限されず、バッチ式でも連続式でもよい。更に、変性反応の反応温度は、反応が進行する限り特に限定されず、重合反応の反応温度をそのまま採用してもよい。なお、変性剤の使用量は、重合体の製造に使用した重合開始剤1molに対し、0.25～3.0molの範囲が好ましく、0.5～1.5molの範囲が更に好ましい。 The modification reaction of the polymerization active site by the modifier is preferably performed by a solution reaction, and the solution may contain a monomer used at the time of polymerization. The reaction mode of the modification reaction is not particularly limited, and may be a batch type or a continuous type. Furthermore, the reaction temperature of the modification reaction is not particularly limited as long as the reaction proceeds, and the reaction temperature of the polymerization reaction may be employed as it is. The amount of the modifying agent used is preferably in the range of 0.25 to 3.0 mol, more preferably in the range of 0.5 to 1.5 mol, with respect to 1 mol of the polymerization initiator used for producing the polymer.
　本発明のランフラットタイヤに用いるゴム組成物においては、上記重合体（Ｂ）を含む反応溶液を乾燥して重合体（Ｂ）を分離した後、得られた重合体（Ｂ）を上記ゴム成分（Ａ）に配合してもよいし、重合体（Ｂ）を含む反応溶液を上記ゴム成分（Ａ）のゴムセメントに溶液状態で混合した後、乾燥して、ゴム成分（Ａ）及び重合体（Ｂ）の混合物を得てもよい。 In the rubber composition used for the run flat tire of the present invention, the reaction solution containing the polymer (B) is dried to separate the polymer (B), and then the obtained polymer (B) is used as the rubber component. The reaction solution containing the polymer (B) may be blended with the rubber cement of the rubber component (A) in a solution state and then dried to obtain the rubber component (A) and the polymer. You may obtain the mixture of (B).
　本発明のランフラットタイヤに用いるゴム組成物においては、上記低分子量共役ジエン系重合体（Ｂ）の含有量が、上記ゴム成分（Ａ）100質量部に対し1～60質量部であることが好ましい。上記低分子量共役ジエン系重合体（Ｂ）の含有量が1質量部未満では、ゴム組成物に作業性を付与する効果が薄く、60質量部を超えると、加硫ゴムの破壊特性が低下する傾向がある。 In the rubber composition used for the run flat tire of the present invention, the content of the low molecular weight conjugated diene polymer (B) is 1 to 60 parts by mass with respect to 100 parts by mass of the rubber component (A). preferable. When the content of the low molecular weight conjugated diene polymer (B) is less than 1 part by mass, the effect of imparting workability to the rubber composition is thin, and when it exceeds 60 parts by mass, the fracture characteristics of the vulcanized rubber are deteriorated. Tend.
　上記ゴム組成物には、上記ゴム成分（Ａ）及び低分子量共役ジエン系重合体（Ｂ）を架橋して、三次元網状構造とするために硫黄等の加硫剤を用いることができる。しかしながら、上記低分子量共役ジエン系重合体（Ｂ）は、その分子量が小さいために架橋され難く、その結果、架橋を形成しない重合体（Ｂ）のフローによってゴム組成物のtanδを上昇させるおそれがある。そこで、上記ゴム組成物は、ゴム成分（Ａ）100質量部に対し、硫黄を3～10質量部含有することが好ましい。該硫黄の含有量が上記の特定した範囲内にあれば、分子量の低い共役ジエン系重合体（Ｂ）を用いてもゴム成分（Ａ）の共役ジエン部分と問題なく三次元網状構造に組み込まれ、低ロス性能を損なうことなく効果的に未加硫粘度を下げることができる。また、該硫黄の含有量が3質量部未満では、硫黄を介した三次元網状構造に関与できず、ロスが高まり、ランフラット耐久性が低下する傾向がある。一方、該硫黄の含有量が10質量部を超えると、熱老化時の再架橋が促進され、ゴムの熱老化性が悪化し、走行劣化によりランフラット耐久性が低下していく傾向がある。 In the rubber composition, a vulcanizing agent such as sulfur can be used for crosslinking the rubber component (A) and the low molecular weight conjugated diene polymer (B) to form a three-dimensional network structure. However, the low molecular weight conjugated diene polymer (B) is difficult to be cross-linked because of its low molecular weight, and as a result, the flow of the polymer (B) that does not form cross-linkage may increase the tan δ of the rubber composition. is there. Therefore, the rubber composition preferably contains 3 to 10 parts by mass of sulfur with respect to 100 parts by mass of the rubber component (A). If the sulfur content is within the above specified range, even if a conjugated diene polymer (B) having a low molecular weight is used, the conjugated diene portion of the rubber component (A) is incorporated into the three-dimensional network structure without any problem. The unvulcanized viscosity can be effectively lowered without impairing the low loss performance. In addition, when the sulfur content is less than 3 parts by mass, the sulfur cannot be involved in the three-dimensional network structure, loss increases, and run-flat durability tends to decrease. On the other hand, when the sulfur content exceeds 10 parts by mass, re-crosslinking during heat aging is promoted, the heat aging property of the rubber is deteriorated, and the run-flat durability tends to decrease due to running deterioration.
　上記ゴム組成物としては、更に充填剤を含有することが好ましい。ここで、充填剤としては、カーボンブラック、シリカ等が挙げられる。カーボンブラックとしては、ＦＥＦ，ＳＲＦ，ＨＡＦ，ＩＳＡＦ，ＳＡＦグレードのものが好ましく、ＨＡＦ，ＩＳＡＦ，ＳＡＦグレードのものが更に好ましい。一方、シリカとしては、湿式シリカ及び乾式シリカ等が好ましく、湿式シリカが更に好ましい。これら充填剤は、一種単独で用いてもよいし、二種以上を混合して用いてもよい。また、上記ゴム組成物においては、充填剤の含有量が上記ゴム成分（Ａ）100質量部に対して30～90質量部であることが好ましい。該充填剤の含有量が30質量部未満では、加硫ゴムの破壊特性及び耐摩耗性が十分でなく、一方、90質量部を超えると、作業性が悪化する傾向がある。 The rubber composition preferably further contains a filler. Here, examples of the filler include carbon black and silica. As carbon black, those of FEF, SRF, HAF, ISAF, and SAF grade are preferable, and those of HAF, ISAF, and SAF grade are more preferable. On the other hand, as silica, wet silica and dry silica are preferable, and wet silica is more preferable. These fillers may be used alone or in combination of two or more. In the rubber composition, the filler content is preferably 30 to 90 parts by mass with respect to 100 parts by mass of the rubber component (A). When the content of the filler is less than 30 parts by mass, the fracture characteristics and wear resistance of the vulcanized rubber are not sufficient, while when it exceeds 90 parts by mass, the workability tends to deteriorate.
　上記ゴム組成物は、更に軟化剤を含んでもよい。ここで、軟化剤としては、パラフィンオイル、ナフテン系オイル、アロマオイル等のプロセスオイルが挙げられ、破壊特性及び耐摩耗性の観点からは、アロマオイルが好ましく、低発熱性及び低温特性の観点からは、ナフテン系オイル及びパラフィンオイルが好ましい。上記軟化剤の配合量は、特に限定されるものではないが、上記低分子量共役ジエン系重合体（Ｂ）及び軟化剤の総配合量が、上記ゴム成分（Ａ）100質量部に対して1～80質量部となるように配合することが好ましい。上記低分子量共役ジエン系重合体（Ｂ）及び軟化剤の総配合量が80質量部を超えると、加硫ゴムの破壊特性が低下する傾向がある。 The rubber composition may further contain a softening agent. Here, examples of the softening agent include process oils such as paraffin oil, naphthenic oil, and aroma oil. Aromatic oil is preferable from the viewpoint of fracture characteristics and wear resistance, and from the viewpoint of low heat buildup and low temperature characteristics. Are preferably naphthenic oils and paraffin oils. The blending amount of the softening agent is not particularly limited, but the total blending amount of the low molecular weight conjugated diene polymer (B) and the softening agent is 1 with respect to 100 parts by mass of the rubber component (A). It is preferable to blend so as to be ˜80 parts by mass. When the total amount of the low molecular weight conjugated diene polymer (B) and the softening agent exceeds 80 parts by mass, the fracture characteristics of the vulcanized rubber tend to deteriorate.
　上記ゴム組成物には、上記ゴム成分（Ａ）、低分子量共役ジエン系重合体（Ｂ）、充填剤、軟化剤の他に、ゴム工業界で通常使用される配合剤、例えば、老化防止剤、シランカップリング剤、加硫促進剤、加硫促進助剤、加硫剤等を、本発明の目的を害しない範囲内で適宜選択して配合することができる。これら配合剤としては、市販品を好適に使用することができる。上記ゴム組成物は、ゴム成分（Ａ）に、低分子量共役ジエン系重合体（Ｂ）と、必要に応じて適宜選択した各種配合剤とを配合して、混練り、熱入れ、押出等することにより製造することができる。 In addition to the rubber component (A), the low molecular weight conjugated diene polymer (B), a filler and a softening agent, the rubber composition contains a compounding agent commonly used in the rubber industry, such as an anti-aging agent. A silane coupling agent, a vulcanization accelerator, a vulcanization acceleration aid, a vulcanizing agent, and the like can be appropriately selected and blended within a range that does not impair the object of the present invention. As these compounding agents, commercially available products can be suitably used. The rubber composition is prepared by blending the rubber component (A) with the low molecular weight conjugated diene polymer (B) and various compounding agents appropriately selected as necessary, kneading, heating, extruding, and the like. Can be manufactured.
　本発明のランフラットタイヤは、ビードフィラー７及びサイド補強ゴム層８の少なくとも一方に、上述のゴム成分（Ａ）及び低分子量共役ジエン系重合体（Ｂ）を含有したゴム組成物を適用して生タイヤを成形し、常法に従って生タイヤを加硫することで製造できる。なお、本発明のランフラットタイヤにおいて、タイヤ内に充填する気体としては、通常の或いは酸素分圧を変えた空気、又は窒素等の不活性ガスを用いることができる。 In the run flat tire of the present invention, a rubber composition containing the rubber component (A) and the low molecular weight conjugated diene polymer (B) is applied to at least one of the bead filler 7 and the side reinforcing rubber layer 8. It can be produced by forming a green tire and vulcanizing the green tire according to a conventional method. In the run flat tire of the present invention, the gas filled in the tire may be normal or air with a changed oxygen partial pressure, or an inert gas such as nitrogen.
＜＜実施例＞＞
　以下に、実施例を挙げて本発明を更に詳しく説明するが、本発明は下記の実施例に何ら限定されるものではない。 << Example >>
Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.
＜重合体（Ａ-１）の製造例１＞
　乾燥し、窒素置換した800mLの耐圧ガラス容器に、シクロヘキサン300g、１,３-ブタジエン40g、スチレン13g、ジテトラヒドロフリルプロパン0.25mmolを加え、更にｎ-ブチルリチウム（ｎ-ＢｕＬｉ）0.25mmolを加えた後、50℃で1.5時間重合反応を行った。この際の重合転化率は、ほぼ100％であった。次に、重合反応系に、変性剤として四塩化スズ0.06mmolを速やかに加え、更に50℃で30分間変性反応を行った。その後、重合反応系に、２,６-ジ-ｔ-ブチル-ｐ-クレゾール（ＢＨＴ）のイソプロパノール溶液（ＢＨＴ濃度：5質量％）0.5mLを加えて、重合反応を停止させ、更に常法に従って乾燥して重合体(Ａ-１)を得た。 <Production Example 1 of Polymer (A-1)>
To a dried and nitrogen-substituted 800 mL pressure-resistant glass container, 300 g of cyclohexane, 40 g of 1,3-butadiene, 13 g of styrene, 0.25 mmol of ditetrahydrofurylpropane, and 0.25 mmol of n-butyllithium (n-BuLi) were added. Thereafter, a polymerization reaction was carried out at 50 ° C. for 1.5 hours. The polymerization conversion rate at this time was almost 100%. Next, 0.06 mmol of tin tetrachloride as a modifier was quickly added to the polymerization reaction system, and a modification reaction was further performed at 50 ° C. for 30 minutes. Thereafter, 0.5 mL of an isopropanol solution (BHT concentration: 5% by mass) of 2,6-di-t-butyl-p-cresol (BHT) was added to the polymerization reaction system to stop the polymerization reaction, and further according to a conventional method. It dried and the polymer (A-1) was obtained.
＜重合体（Ｂ-１）の製造例＞
　乾燥し、窒素置換した800mLの耐圧ガラス容器に、シクロへキサン300g、１,３-ブタジエン50g、ジテトラヒドロフリルプロパン0.040mmolを注入し、更にｎ-ブチルリチウム（ｎ-ＢｕＬｉ）1.32mmolを加えた後、50℃で1.5時間重合反応を行った。この際の重合転化率は、ほぼ100％であった。その後、重合反応系に、２,６-ジ-ｔ-ブチル-ｐ-クレゾール（ＢＨＴ）のイソプロパノール溶液（ＢＨＴ濃度：5質量％）0.5mLを加えて、重合反応を停止させ、更に常法に従って乾燥して重合体（Ｂ-１）を得た。 <Example of production of polymer (B-1)>
Into an 800 mL pressure-resistant glass container that has been dried and purged with nitrogen, 300 g of cyclohexane, 50 g of 1,3-butadiene and 0.040 mmol of ditetrahydrofurylpropane were injected, and further 1.32 mmol of n-butyllithium (n-BuLi) was added. Thereafter, a polymerization reaction was carried out at 50 ° C. for 1.5 hours. The polymerization conversion rate at this time was almost 100%. Thereafter, 0.5 mL of an isopropanol solution (BHT concentration: 5% by mass) of 2,6-di-t-butyl-p-cresol (BHT) was added to the polymerization reaction system to stop the polymerization reaction, and further according to a conventional method. It dried and the polymer (B-1) was obtained.
＜重合体（Ｂ-２）～（Ｂ-５）及び（Ｂ-７）の製造例＞
　ｎ-ブチルリチウム（ｎ-ＢｕＬｉ）の使用量を変えた他は上記重合体（Ｂ-１）の製造例と同様にして重合体（Ｂ-２）～（Ｂ-５）及び（Ｂ-７）を合成した。 <Production Examples of Polymers (B-2) to (B-5) and (B-7)>
The polymers (B-2) to (B-5) and (B-7) were prepared in the same manner as in the production example of the polymer (B-1) except that the amount of n-butyllithium (n-BuLi) was changed. ) Was synthesized.
＜重合体（Ｂ-６）の製造例＞
　乾燥し、窒素置換した800mLの耐圧ガラス容器に、シクロへキサン300g、１,３-ブタジエン42.5g、スチレン7.5g、ジテトラヒドロフリルプロパン0.025mmolを注入し、更にｎ-ブチルリチウム（ｎ-ＢｕＬｉ）1.32mmolを加えた後、50℃で1.5時間重合反応を行った。この際の重合転化率は、ほぼ100％であった。その後、重合反応系に、２,６-ジ-ｔ-ブチル-ｐ-クレゾール（ＢＨＴ）のイソプロパノール溶液（ＢＨＴ濃度：5質量％）0.5mLを加えて、重合反応を停止させ、更に常法に従って乾燥して重合体（Ｂ-６）を得た。 <Production example of polymer (B-6)>
Into an 800 mL pressure-resistant glass container that has been dried and purged with nitrogen, 300 g of cyclohexane, 42.5 g of 1,3-butadiene, 7.5 g of styrene, and 0.025 mmol of ditetrahydrofurylpropane are injected, and n-butyllithium (n-BuLi) is added. After adding 1.32 mmol, a polymerization reaction was carried out at 50 ° C. for 1.5 hours. The polymerization conversion rate at this time was almost 100%. Thereafter, 0.5 mL of an isopropanol solution (BHT concentration: 5% by mass) of 2,6-di-t-butyl-p-cresol (BHT) was added to the polymerization reaction system to stop the polymerization reaction, and further according to a conventional method. It dried and the polymer (B-6) was obtained.
　上記のようにして製造した重合体（Ａ-１）及び（Ｂ-１）～（Ｂ-７）の重量平均分子量（Ｍw）、ミクロ構造を下記の方法で測定した。結果を表１に示す。 The weight average molecular weight (Mw) and microstructure of the polymers (A-1) and (B-1) to (B-7) produced as described above were measured by the following methods. The results are shown in Table 1.
（１）重量平均分子量（Ｍw）
　ゲルパーミエーションクロマトグラフィー［ＧＰＣ：東ソー製ＨＬＣ－８０２０、カラム：東ソー製ＧＭＨ－ＸＬ（２本直列）、検出器：示差屈折率計（ＲＩ）］で単分散ポリスチレンを基準として、各重合体のポリスチレン換算の重量平均分子量（Ｍw）を求めた。 (1) Weight average molecular weight (Mw)
Gel permeation chromatography [GPC: Tosoh HLC-8020, column: Tosoh GMH-XL (two in series), detector: differential refractometer (RI)], based on monodisperse polystyrene, The weight average molecular weight (Mw) in terms of polystyrene was determined.
（２）ミクロ構造
　重合体のミクロ構造を赤外法（モレロ法）で求めた。 (2) Microstructure The microstructure of the polymer was determined by an infrared method (Morero method).
Figure JPOXMLDOC01-appb-I000001
Figure JPOXMLDOC01-appb-I000001
（実施例１～５及び比較例１～５）
　表２に示す配合処方のゴム組成物を調製し、該ゴム組成物をビードフィラー７及びサイド補強ゴム層８の双方に用いて、図１に示す構造を有し、サイズが２４５／４０Ｒ１８のランフラットタイヤを製造した。 (Examples 1 to 5 and Comparative Examples 1 to 5)
A rubber composition having a compounding formulation shown in Table 2 was prepared, and the rubber composition was used for both the bead filler 7 and the side reinforcing rubber layer 8 to have the structure shown in FIG. 1 and have a size of 245 / 40R18. A flat tire was manufactured.
＜評価＞
　上記のようにして作製したタイヤに対して、下記の方法で、ランフラット耐久性を評価した。結果を表２に示す。 <Evaluation>
The tire produced as described above was evaluated for run-flat durability by the following method. The results are shown in Table 2.
（３）ランフラット耐久性
　各試作タイヤを常圧でリム組みし、内圧230kPaを封入してから38℃の室温中に24時間放置後、バルブのコアを抜き内圧を大気圧として、荷重5.19kN（530kg）、速度89km/h、室温38℃の条件でドラム走行テストを行った。この際の故障発生までの走行距離を測定し、比較例１の故障発生までの走行距離を100として指数表示した。指数値が大きい程、故障発生までの走行距離が長く、ランフラット耐久性に優れることを示す。なお、各例とも、サイド補強ゴム層とビードフィラーの双方に上記ゴム組成物を用いた。 (3) Run flat durability Each prototype tire is assembled with rims at normal pressure, filled with an internal pressure of 230 kPa, and left in a room temperature of 38 ° C. for 24 hours. The drum running test was conducted under the conditions of (530 kg), speed 89 km / h, and room temperature 38 ° C. The distance traveled until the failure occurred at this time was measured, and the travel distance until the failure occurred in Comparative Example 1 was taken as 100 and displayed as an index. The larger the index value, the longer the distance traveled until the failure occurs, indicating better run-flat durability. In each example, the rubber composition was used for both the side reinforcing rubber layer and the bead filler.
Figure JPOXMLDOC01-appb-I000002
Figure JPOXMLDOC01-appb-I000002
*1　ポリスチレン換算重量平均分子量＝1,500,000．
*2　重合体（Ａ-１）．
*3　ＪＳＲ(株)製，ＢＲ０１，ポリスチレン換算重量平均分子量＝550,000.
*4　Ｎ-(１,３-ジメチルブチル)-Ｎ'-フェニル-ｐ-フェニレンジアミン.
*5　ＮＳ：Ｎ-tert-ブチル-２-ベンゾチアジル-スルフェンアミド． * 1 Polystyrene equivalent weight average molecular weight = 1,500,000.
* 2 Polymer (A-1).
* 3 JSR, BR01, polystyrene equivalent weight average molecular weight = 550,000.
* 4 N- (1,3-Dimethylbutyl) -N'-phenyl-p-phenylenediamine.
* 5 NS: N-tert-butyl-2-benzothiazyl-sulfenamide.
　比較例１及び比較例２の比較から、ゴム組成物中にオイル等の軟化剤を配合することで、ランフラット耐久性が大幅に低下することが分かる。しかし、実施例１～５の結果から、オイル等の軟化剤の一部に代えて、ゲル浸透クロマトグラフィーで測定したポリスチレン換算重量平均分子量が10,000～200,000で、構成する単量体単位の全体に占める芳香族ビニル化合物単位の割合が5質量％未満の低分子量共役ジエン系重合体（Ｂ）を配合したゴム組成物を用いることで、ランフラット耐久性が大幅に向上できることが分かる。 From the comparison between Comparative Example 1 and Comparative Example 2, it can be seen that the run-flat durability is greatly reduced by blending a softener such as oil in the rubber composition. However, from the results of Examples 1 to 5, the polystyrene-converted weight average molecular weight measured by gel permeation chromatography was 10,000 to 200,000 instead of a part of the softening agent such as oil, and the entire monomer unit was composed. It can be seen that run-flat durability can be greatly improved by using a rubber composition containing a low molecular weight conjugated diene polymer (B) in which the proportion of the aromatic vinyl compound unit is less than 5% by mass.
　また、比較例５では、低分子量共役ジエン系重合体（Ｂ）のポリスチレン換算重量平均分子量が10,000～200,000の範囲から外れており、ランフラット耐久性の向上効果が十分に得られず、比較例４では、低分子量共役ジエン系重合体（Ｂ）のスチレン単位の割合が高過ぎるため、ランフラット耐久性の向上効果が十分に得られないことが分かる。更に、比較例３では、ゴム成分（Ａ）が天然ゴム及び／又はポリイソプレンゴムを含んでいないため、ランフラット耐久性が悪化することが分かる。 In Comparative Example 5, the low molecular weight conjugated diene polymer (B) has a polystyrene-equivalent weight average molecular weight outside the range of 10,000 to 200,000, and the effect of improving run-flat durability is not sufficiently obtained. In No. 4, since the ratio of the styrene unit of the low molecular weight conjugated diene polymer (B) is too high, the effect of improving the run flat durability cannot be sufficiently obtained. Furthermore, in the comparative example 3, since rubber component (A) does not contain natural rubber and / or polyisoprene rubber, it turns out that run flat durability deteriorates.
　１　ビード部
　２　サイドウォール部
　３　トレッド
　４　ラジアルカーカス
　４ａ　折り返しカーカスプライ
　４ｂ　ダウンカーカスプライ
　５　ベルト
　６　ビードコア
　７　ビードフィラー
　８　サイド補強ゴム層 DESCRIPTION OF SYMBOLS 1 Bead part 2 Side wall part 3 Tread 4 Radial carcass 4a Folded carcass ply 4b Down carcass ply 5 Belt 6 Bead core 7 Bead filler 8 Side reinforcement rubber layer

Claims (9)

  1. 　サイドウォール部、トレッド、カーカス、ビードコア及びビードフィラーを備えたランフラットタイヤにおいて、
    　前記ビードフィラーに、少なくとも天然ゴム及び／又はポリイソプレンゴムを含むゴム成分（Ａ）に対し、ゲル浸透クロマトグラフィーで測定したポリスチレン換算重量平均分子量が10,000～200,000で、構成する単量体単位の全体に占める芳香族ビニル化合物の割合が5質量％未満の低分子量共役ジエン系重合体（Ｂ）を配合してなるゴム組成物を用いたことを特徴とするランフラットタイヤ。     In the run-flat tire with the sidewall portion, tread, carcass, bead core and bead filler,
    The entire monomer unit constituting the bead filler having a weight average molecular weight in terms of polystyrene measured by gel permeation chromatography of 10,000 to 200,000 for the rubber component (A) containing at least natural rubber and / or polyisoprene rubber. A run-flat tire comprising a rubber composition comprising a low molecular weight conjugated diene polymer (B) having an aromatic vinyl compound content of less than 5% by mass.
  2. 　サイドウォール部、トレッド、カーカス及びサイド補強ゴム層を備えたランフラットタイヤにおいて、
    　前記サイド補強ゴム層に、少なくとも天然ゴム及び／又はポリイソプレンゴムを含むゴム成分（Ａ）に対し、ゲル浸透クロマトグラフィーで測定したポリスチレン換算重量平均分子量が10,000～200,000で、構成する単量体単位の全体に占める芳香族ビニル化合物の割合が5質量％未満の低分子量共役ジエン系重合体（Ｂ）を配合してなるゴム組成物を用いたことを特徴とするランフラットタイヤ。     In the run flat tire provided with the sidewall portion, the tread, the carcass and the side reinforcing rubber layer,
    A monomer unit comprising a rubber component (A) containing at least natural rubber and / or polyisoprene rubber in the side reinforcing rubber layer and having a polystyrene-reduced weight average molecular weight of 10,000 to 200,000 as measured by gel permeation chromatography A run-flat tire characterized by using a rubber composition comprising a low molecular weight conjugated diene polymer (B) in which the ratio of the aromatic vinyl compound to the whole is less than 5% by mass.
  3. 　サイドウォール部、トレッド、カーカス、ビードコア、ビードフィラー及びサイド補強ゴム層を備えたランフラットタイヤにおいて、
    　前記ビードフィラー及び前記サイド補強ゴム層に、少なくとも天然ゴム及び／又はポリイソプレンゴムを含むゴム成分（Ａ）に対し、ゲル浸透クロマトグラフィーで測定したポリスチレン換算重量平均分子量が10,000～200,000で、構成する単量体単位の全体に占める芳香族ビニル化合物の割合が5質量％未満の低分子量共役ジエン系重合体（Ｂ）を配合してなるゴム組成物を用いたことを特徴とするランフラットタイヤ。     In the run flat tire including the sidewall portion, the tread, the carcass, the bead core, the bead filler, and the side reinforcing rubber layer,
    The bead filler and the side reinforcing rubber layer are composed of a rubber component (A) containing at least natural rubber and / or polyisoprene rubber and having a polystyrene equivalent weight average molecular weight of 10,000 to 200,000 measured by gel permeation chromatography. A run flat tire using a rubber composition comprising a low molecular weight conjugated diene polymer (B) in which the ratio of an aromatic vinyl compound to the whole monomer units is less than 5% by mass.
  4. 　前記ゴム成分（Ａ）が、天然ゴム、ポリイソプレンゴム、スチレン－ブタジエン共重合体ゴム、ポリブタジエンゴム及びイソブチレンイソプレンゴムからなる群から選択される少なくとも一種からなることを特徴とする請求項１～３のいずれかに記載のランフラットタイヤ。 The rubber component (A) comprises at least one selected from the group consisting of natural rubber, polyisoprene rubber, styrene-butadiene copolymer rubber, polybutadiene rubber, and isobutylene isoprene rubber. The run flat tire according to any one of the above.
  5. 　前記低分子量共役ジエン系重合体（Ｂ）は、共役ジエン化合物部分のビニル結合量が40％以上であることを特徴とする請求項１～３のいずれかに記載のランフラットタイヤ。 The run-flat tire according to any one of claims 1 to 3, wherein the low molecular weight conjugated diene polymer (B) has a vinyl bond content of a conjugated diene compound portion of 40% or more.
  6. 　前記低分子量共役ジエン系重合体（Ｂ）の含有量が、上記ゴム成分（Ａ）100質量部に対し1～60質量部であることを特徴とする請求項１～３のいずれかに記載のランフラットタイヤ。 The content of the low molecular weight conjugated diene polymer (B) is 1 to 60 parts by mass with respect to 100 parts by mass of the rubber component (A). Run flat tire.
  7. 　前記低分子量共役ジエン系重合体（Ｂ）がポリブタジエンであることを特徴とする請求項１～３のいずれかに記載のランフラットタイヤ。 The run-flat tire according to any one of claims 1 to 3, wherein the low molecular weight conjugated diene polymer (B) is polybutadiene.
  8. 　前記ゴム組成物が、更にカーボンブラック及び／又はシリカを含有することを特徴とする請求項１～３のいずれかに記載のランフラットタイヤ。 The run flat tire according to any one of claims 1 to 3, wherein the rubber composition further contains carbon black and / or silica.
  9. 　前記ゴム組成物が、更に硫黄をゴム成分（Ａ）100質量部に対し3～10質量部含有することを特徴とする請求項１～３のいずれかに記載のランフラットタイヤ。 The run-flat tire according to any one of claims 1 to 3, wherein the rubber composition further contains 3 to 10 parts by mass of sulfur with respect to 100 parts by mass of the rubber component (A).
PCT/JP2009/064878 2009-08-26 2009-08-26 Run-flat tire WO2011024268A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/JP2009/064878 WO2011024268A1 (en) 2009-08-26 2009-08-26 Run-flat tire

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP2009/064878 WO2011024268A1 (en) 2009-08-26 2009-08-26 Run-flat tire

Publications (1)

Publication Number Publication Date
WO2011024268A1 true WO2011024268A1 (en) 2011-03-03

Family

ID=43627395

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2009/064878 WO2011024268A1 (en) 2009-08-26 2009-08-26 Run-flat tire

Country Status (1)

Country Link
WO (1) WO2011024268A1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110546195A (en) * 2017-04-25 2019-12-06 株式会社普利司通 Rubber composition for run-flat tire and run-flat tire
EP3617265A4 (en) * 2017-04-25 2020-09-23 Bridgestone Corporation Run-flat tire rubber composition and run-flat tire
JP7398266B2 (en) 2019-12-19 2023-12-14 株式会社ブリヂストン Rubber composition for run-flat tires, method for producing the same, and run-flat tires

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005280534A (en) * 2004-03-30 2005-10-13 Sumitomo Rubber Ind Ltd Run-flat tire
JP2007224305A (en) * 2007-03-08 2007-09-06 Sumitomo Rubber Ind Ltd Run-flat tire
JP2007276589A (en) * 2006-04-05 2007-10-25 Bridgestone Corp Pneumatic tire
JP2008031207A (en) * 2006-07-26 2008-02-14 Yokohama Rubber Co Ltd:The Run flat tire
JP2008063364A (en) * 2006-09-04 2008-03-21 Bridgestone Corp Rubber composition and pneumatic tire using the same
JP2008106148A (en) * 2006-10-25 2008-05-08 Bridgestone Corp Rubber composition for run-flat tire and run-flat tire comprised of the same

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005280534A (en) * 2004-03-30 2005-10-13 Sumitomo Rubber Ind Ltd Run-flat tire
JP2007276589A (en) * 2006-04-05 2007-10-25 Bridgestone Corp Pneumatic tire
JP2008031207A (en) * 2006-07-26 2008-02-14 Yokohama Rubber Co Ltd:The Run flat tire
JP2008063364A (en) * 2006-09-04 2008-03-21 Bridgestone Corp Rubber composition and pneumatic tire using the same
JP2008106148A (en) * 2006-10-25 2008-05-08 Bridgestone Corp Rubber composition for run-flat tire and run-flat tire comprised of the same
JP2007224305A (en) * 2007-03-08 2007-09-06 Sumitomo Rubber Ind Ltd Run-flat tire

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110546195A (en) * 2017-04-25 2019-12-06 株式会社普利司通 Rubber composition for run-flat tire and run-flat tire
EP3617265A4 (en) * 2017-04-25 2020-09-23 Bridgestone Corporation Run-flat tire rubber composition and run-flat tire
CN110546195B (en) * 2017-04-25 2022-03-22 株式会社普利司通 Rubber composition for run-flat tire and run-flat tire
JP7398266B2 (en) 2019-12-19 2023-12-14 株式会社ブリヂストン Rubber composition for run-flat tires, method for producing the same, and run-flat tires

Similar Documents

Publication Publication Date Title
JP5436203B2 (en) Rubber composition and pneumatic tire using the same
WO2011030431A1 (en) Run-flat tire
RU2670897C2 (en) Rubber composition for tires and pneumatic tire
JP6225447B2 (en) Rubber composition for tire tread
JP2004249873A (en) Pneumatic tire
US20090171029A1 (en) Styrene-based polymer, styrene-based copolymer, rubber composition and pneumatic tire
JP6743362B2 (en) Rubber composition for tires
WO2011024268A1 (en) Run-flat tire
JP5363803B2 (en) Pneumatic tire
JP5174502B2 (en) Run flat tire
JP7138645B2 (en) pneumatic tire
JP7002539B2 (en) Rubber composition for run-flat tires and run-flat tires
JP2009234363A (en) Run-flat tire
JP6651787B2 (en) Rubber composition for tire
JP6968159B2 (en) Rubber composition for run-flat tires and run-flat tires
JP5508066B2 (en) Rubber composition for tire and pneumatic tire
JP6651788B2 (en) Rubber composition for tire
JP2002079803A (en) Pneumatic tire
WO2018150882A1 (en) Conjugated diene polymer, rubber composition, crosslinked rubber, rubber product, and tire
JP7188521B1 (en) Rubber composition for tires
JP5962809B1 (en) Rubber composition for tire tread and pneumatic tire using the same
JP2023151211A (en) Rubber composition and tire

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 09848716

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 09848716

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: JP