JP6908222B2 - Side reinforcing rubber composition for run-flat tires, side reinforcing rubber for run-flat tires, and run-flat tires - Google Patents

Description

The present invention relates to a side reinforcing rubber composition for a run-flat tire, a side reinforcing rubber for a run-flat tire, and a run-flat tire.

Conventionally, in tires, particularly run-flat tires, a side reinforcing layer made of a rubber composition alone or a composite of a rubber composition and fibers is provided in order to improve the rigidity of the sidewall portion.
For example, as a rubber composition for a run flat tire that improves run flat performance, a rubber component containing natural rubber, carbon black, and zinc oxide are contained, and the ratio of the natural rubber in 100% by mass of the rubber component is The carbon black has an iodine adsorption amount of 82 mg / g or more, a dibutylphthalate oil absorption amount of 69 ml / 100 g or more, and the content of the carbon black with respect to 100 parts by mass of the rubber component. A rubber composition having 60 parts by mass or more and having a zinc oxide content of 10 parts by mass or more is disclosed (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2011-74241

In Patent Document 1, a rubber composition containing a predetermined amount of natural rubber (NR), a predetermined amount of carbon black having a specific iodine adsorption amount and dibutylphthalate (DBP) oil absorption amount, and a predetermined amount of zinc oxide is used. We are trying to improve the durability of run-flat tires by using them.

However, with the improvement of the performance of automobiles, especially passenger cars, further improvement of run-flat durability is required.
INDUSTRIAL APPLICABILITY The present invention includes a side reinforcing rubber for run-flat tires having excellent durability without impairing low heat generation, a side reinforcing rubber composition for run-flat tires capable of producing the same, and a side reinforcing rubber composition for run-flat tires without impairing low heat generation. The challenge is to provide run-flat tires with excellent durability.

<1> A rubber component containing diene rubber, a vulcanizing agent, a nitrogen adsorption method, a specific surface area of 10 to 40 ^{m 2} / g, a dibutyl phthalate oil absorption amount of 100 to 180 mL / 100 g, and a compressed dibutyl phthalate oil absorption amount of 36 to 36 to The carbon black containing 110 ml / 100 g, the interparticle distance S of the carbon black represented by the following formula (1) is 40 to 150 nm, and the carbon black represented by the following formula (2) and the above. This is a side reinforcing rubber composition for a run flat tire having a volume ratio φβ of an agglomerate composed of occluder rubber stored in carbon black of 0.25 to 0.45.

In the formula (1), Dst represents the most frequent value (nm) of the distribution curve having a diameter equivalent to Stokes, and ΔD50 represents the half width (nm) of the distribution curve with respect to the Dst. φβ represents the volume ratio of the aggregate composed of the carbon black and the occluded occluder rubber, and is calculated by the following formula (2).

Wherein (2), phi represents the ratio _(V CB / V _G) of the total volume _V CB carbon black to the total volume _V G (ml) (ml) of the rubber _{composition, V occ} is O crude rubber volume the stands, V _a represents the volume of the carbon black aggregates. 24M4DBP represents the compressed dibutyl phthalate oil absorption (ml / 100 g) of carbon black.

<2> The side reinforcing rubber composition for a run-flat tire according to <1>, wherein the content of the carbon black is 40 to 100 parts by mass with respect to 100 parts by mass of the rubber component.

<3> The side reinforcing rubber composition for a run-flat tire according to <1> or <2>, wherein the diene-based rubber contains a synthetic diene-based rubber.
<4> The side reinforcement for a run-flat tire according to <3>, wherein the synthetic diene rubber contains a modified rubber having a modified functional group containing at least one selected from the group consisting of a tin atom, an oxygen atom and a nitrogen atom. It is a rubber composition.
<5> The run-flat tire according to any one of <1> to <4>, wherein the content of natural rubber in the rubber component is 20 to 99% by mass and the content of polybutadiene rubber is 1 to 80% by mass. Side reinforcing rubber composition for use.

<6> The side reinforcing rubber composition for a run-flat tire according to any one of <1> to <5>, which contains a vulcanization accelerator containing a thiuram compound.
<7> The thiuram compound is the side reinforcing rubber composition for a run-flat tire according to <6>, which has 4 or more side chain carbon atoms.

<8> A side reinforcing rubber for a run-flat tire using the side reinforcing rubber composition for a run-flat tire according to any one of <1> to <7>.

<9> A run-flat tire using the side reinforcing rubber for a run-flat tire according to <8>.

According to the present invention, a side reinforcing rubber for a run-flat tire having excellent durability, a side reinforcing rubber composition for a run-flat tire capable of producing the same, and a low heat generating property are impaired without impairing low heat generation. It is possible to provide a run-flat tire having excellent durability.

It is a schematic diagram which shows the cross section of one Embodiment of the run-flat tire of this invention.

<Side reinforcing rubber composition for run-flat tires>
The side reinforcing rubber composition for a run-flat tire of the present invention is
Rubber components including diene rubber and
Vulcanizer and
Nitrogen adsorption method Contains carbon black having a specific surface area of 10 to 40 ^{m 2} / g, dibutyl phthalate oil absorption of 100 to 180 mL / 100 g, and compressed dibutyl phthalate oil absorption of 36 to 110 ml / 100 g.
The interparticle distance S of the carbon black represented by the following formula (1) is 40 to 150 nm, and the carbon black represented by the following formula (2) and the occluder rubber occluded in the carbon black are coagulated. The volume ratio φβ of the aggregate is 0.25 to 0.45.
Hereinafter, the side reinforcing rubber composition for a run-flat tire may be simply referred to as a "rubber composition".

In the formula (1), Dst represents the most frequent value (nm) of the distribution curve having a diameter equivalent to Stokes, and ΔD50 represents the half width (nm) of the distribution curve with respect to the Dst. φβ represents the volume ratio of the agglomerates composed of the carbon black and the occluder rubber occluded in the carbon black, and is calculated by the following formula (2).

Wherein (2), phi represents the ratio _(V CB / V _G) of the total volume _V CB carbon black to the total volume _V G (ml) (ml) of the rubber _{composition, V occ} is O crude rubber volume the stands, V _a represents the volume of the carbon black aggregates. 24M4DBP represents the compressed dibutyl phthalate oil absorption (ml / 100 g) of carbon black.

Since carbon black usually exists as a structure in which primary particles are aggregated and chained particles are branched, the rubber component enters between the branched chain particles in the rubber composition. The rubber component occluded in the branched structure of carbon black in this way is called an occluder rubber. Since the occlusal rubber is restrained by the carbon black of the chain particles of the carbon black branches, it is difficult to be deformed by an external load, and thus functions as a component for reinforcing the rubber composition together with the carbon black. There is a tendency.
The durability of the rubber composition can be improved by using carbon black with a high structure that easily occludes a large amount of occluder rubber, but the more particles that are chained, the greater the friction between the particles and the vulcanized rubber. It was easy to increase fever.
The present inventor focused on the existence state of the occluded rubber stored in carbon black, and the volume ratio φβ of the aggregate composed of the carbon black in the rubber component and the occluded occluded rubber, and the interparticle distance of the carbon black. It has been found that by controlling S, durability is improved while suppressing heat generation of the side reinforcing rubber for run flat tires.

[Equation (1), Equation (2)]
In the formula (1), Dst represents the size of the agglomerates of carbon black, exp [(ΔD50 / 2Dst) ² ] represents the distribution of the agglomerates of carbon black, and “[(0.86 / (φβ)”. ) ^1/3 ) -1] ”corresponds to the content of carbon black in the rubber composition.
The inter-particle distance S of carbon black depends on the content of carbon black in the rubber composition. The larger the content, the smaller the inter-particle distance S, the closer the particles are, and the smaller the content, the inter-particle distance S. The particles tend to separate from each other, but it is thought that this also affects the size of the agglomerates, which is how well the carbon black structure is developed.
The inter-particle distance S is 40 to 150 nm, and if it is smaller than 40 nm, the particles come into contact with each other more often, which impairs the low heat generation of the side reinforcing rubber for the run-flat tire. If it is larger than 150 nm, the carbon black particles are separated and it becomes difficult to form a network structure between the carbon black particles, so that the reinforcing property is reduced and the durability of the side reinforcing rubber for the run-flat tire is not excellent. ..
From the above viewpoint, the interparticle distance S is preferably 45 to 135 nm.

The volume ratio φβ of the carbon black contained in the formula (1) and the aggregate composed of the occluder rubber occluded in the carbon black can be obtained by the formula (2). φ is the total volume of the carbon black to the total volume _{(V G)} of the rubber composition _{(V CB),} obtained as _V CB / V _G. β is OH crude dependent on rubber volume _{(V OCC),} "1 + [(24M4DBP-31) from the compressed dibutyl phthalate oil absorption of carbon black (24M4DBP) to the volume of aggregates _{(V a)} of the carbon black / 55 ] ”Can be calculated.
The volume ratio φβ depends on the volume ratio of the rubber component and the carbon black and the degree of development of the structure of the carbon black, and if φ is increased or β is increased, φβ becomes large. φ tends to increase as the volume ratio of carbon black in the rubber component increases. β tends to increase as the amount of occlusal rubber that can be occluded in carbon black increases. In other words, the more complicated the structure of carbon black, in other words, the larger the 24M4DBP, the larger β tends to be.
The volume ratio φβ is 0.25 to 0.45, and if it is smaller than 0.25, the durability of the side reinforcing rubber for run-flat tires is impaired, and if it is larger than 0.45, the side reinforcing rubber for run-flat tires Impairs low heat generation.
From the viewpoint of improving durability without impairing the low heat generation of the side reinforcing rubber for run-flat tires, the volume ratio φβ is preferably 0.3 to 0.4, preferably 0.35 to 0.4. More preferably.

[Rubber component]
The side reinforcing rubber composition for a run-flat tire of the present invention contains at least a rubber component containing a diene-based rubber.
As the diene-based rubber, at least one selected from the group consisting of natural rubber (NR) and synthetic diene-based rubber is used.
Specific examples of the synthetic diene rubber include polyisoprene rubber (IR), polybutadiene rubber (BR), styrene-butadiene copolymer rubber (SBR), butadiene-isoprene copolymer rubber (BIR), and styrene-isoprene. Examples thereof include polymer rubber (SIR) and styrene-butadiene-isoprene copolymer rubber (SBIR).
As the diene rubber, natural rubber, polyisoprene rubber, styrene-butadiene copolymer rubber, polybutadiene rubber, and isobutylene isoprene rubber are preferable, and natural rubber and polybutadiene rubber are more preferable. The diene rubber may be used alone or in a blend of two or more.

As the diene rubber, only one of natural rubber and synthetic diene rubber may be used, or both may be used, but the breaking characteristics such as tensile strength and breaking elongation of the side reinforcing rubber for run flat tires are improved. However, from the viewpoint of improving durability, it is preferable to use natural rubber and synthetic diene rubber in combination.
From the viewpoint of further improving the durability of the side reinforcing rubber for run flat tires, the content of natural rubber in the rubber component is preferably 20 to 99% by mass, and that of synthetic diene rubber is preferably 1 to 80% by mass. , The content of natural rubber is 20 to 99% by mass, more preferably 1 to 80% by mass of polybutadiene rubber, the content of natural rubber is 30 to 70% by mass, and the content of polybutadiene rubber is 30 to 70. It is more preferably by mass%, the content of the natural rubber is 35 to 65% by mass, and the content of the polybutadiene rubber is even more preferably 35 to 65% by mass.
The rubber component may contain non-diene rubber as long as the effect of the present invention is not impaired.

The synthetic diene rubber is a modified rubber having a modified functional group containing at least one selected from the group consisting of tin atoms, oxygen atoms and nitrogen atoms from the viewpoint of improving the low heat generation of the side reinforcing rubber for run-flat tires. It is preferable to include it. In order to enhance the interaction with carbon black, the synthetic diene rubber preferably contains a modified butadiene rubber.
A modified functional group containing at least one selected from the group consisting of a tin atom, an oxygen atom and a nitrogen atom functions as a functional group that interacts with carbon black, and the modified functional group is specifically a tin-containing functional group. , At least one selected from the group consisting of an oxygen-containing functional group and a nitrogen-containing functional group is preferable.

When the modified butadiene rubber is a modified butadiene rubber having at least one functional group selected from the group consisting of a tin-containing functional group, an oxygen-containing functional group and a nitrogen-containing functional group, the modified butadiene rubber is a tin-containing compound. , It is preferably modified with a denaturing agent such as an oxygen-containing compound or a nitrogen-containing compound, and a tin-containing functional group, an oxygen-containing functional group, a nitrogen-containing functional group or the like is introduced.
When the polymerization active site of the butadiene rubber is modified with a modifier, the modifier used is preferably a nitrogen-containing compound, an oxygen-containing compound and a tin-containing compound. In this case, a nitrogen-containing functional group, an oxygen-containing functional group or a tin-containing functional group can be introduced by a modification reaction.
Such a modification functional group may be present at any of the polymerization initiation terminal, main chain and polymerization active end of polybutadiene.

The nitrogen-containing compound that can be used as the modifier preferably has a substituted or unsubstituted amino group, amide group, imino group, imidazole group, nitrile group or pyridyl group. Suitable nitrogen-containing compounds as the modifier include isocyanate compounds such as diphenylmethane diisocyanate, crude MDI, trimethylhexamethylene diisocyanate, and tolylene diisocyanate, 4- (dimethylamino) benzophenone, 4- (diethylamino) benzophenone, and 4-dimethylamino. Examples thereof include benzylene aniline, 4-dimethylaminobenzylene butylamine, dimethylimidazolidinone, N-methylpyrrolidone hexamethyleneimine and the like.

Examples of the oxygen-containing compound that can be used as the modifier include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, and N- (1-methylpropanol) -3- (tri). Ethoxysilyl) -1-propaneamine, N- (1,3-dimethylbutylidene) -3- (triethoxysilyl) -1-propaneamine, N- (3-triethoxysilylpropyl) -4,5-dihydro Imidazole, 3-methacryloyloxypropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-triethoxysilylpropylsuccinate anhydride, 3- (1-hexamethyleneimino) propyl (triethoxy) silane, (1- Hexamethylene imino) methyl (trimethoxy) silane, 3-diethylaminopropyl (triethoxy) silane, 3-dimethylaminopropyl (triethoxy) silane, 2- (trimethoxysilylethyl) pyridine, 2- (triethoxysilylethyl) pyridine, 2 -Cyanoethyltriethoxysilane, tetraethoxysilane and the like can be mentioned. These oxygen-containing compounds may be used alone or in combination of two or more. Further, a partial condensate of the oxygen-containing compound can also be used.

Further, as the denaturant, the following formula (I):
R ¹ _a ZX _b (I)
[In the formula, R ¹ is independently composed of an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, and an aralkyl group having 7 to 20 carbon atoms. Selected from the group; Z is tin or silicon; X is independently chlorine or bromine; a is 0-3, b is 1-4, where a + b = 4]. The modified agent represented is also preferred. The modified butadiene rubber obtained by modifying with the modifier of the formula (I) has at least one kind of tin-carbon bond or silicon-carbon bond.

^{Specific examples of R 1} of the formula (I) include a methyl group, an ethyl group, an n-butyl group, a neofil group, a cyclohexyl group, an n-octyl group, a 2-ethylhexyl group and the like. Specifically, as the denaturant of the formula (I), SnCl ₄ , R ¹ SnCl ₃ , R ¹ ₂ SnCl ₂ , R ¹ ₃ SnCl, SiCl ₄ , R ¹ SiCl ₃ , R ¹ ₂ SiCl ₂ , R ¹ ₃ SiCl and the like are preferable, SnCl ₄ and SiCl ₄ are particularly preferred.

Among the above, the modified butadiene rubber is a modified butadiene rubber having a nitrogen-containing functional group from the viewpoint of reducing the heat generation of the side reinforcing rubber for run flat tires and extending the durable life of the side reinforcing rubber for run flat tires. It is preferably an amine-modified butadiene rubber, more preferably.
Further, the amine-modified butadiene rubber is preferably one in which a primary amino group protected by a removable group or a secondary amino group protected by a removable group is introduced as an amine-based functional group for modification. Further, those having a functional group containing a silicon atom introduced are preferable.
Examples of a primary amino group protected by a removable group (also referred to as a protected primary amino group) include an N, N-bis (trimethylsilyl) amino group, which is a removable group. Examples of the secondary amino group protected by N, N- (trimethylsilyl) alkylamino group can be mentioned. The N, N- (trimethylsilyl) alkylamino group-containing group may be either an acyclic residue or a cyclic residue.
Among the above amine-modified butadiene rubbers, a primary amine-modified butadiene rubber modified with a protected primary amino group is more preferable.
Examples of the functional group containing an oxygen atom include a hydrocarbyloxysilyl group and / or a silanol group formed by bonding a hydrocarbyloxy group and / or a hydroxy group to a silicon atom.
Such a functional group for modification preferably comprises a silicon atom in which an amino group protected by a removable group, a hydrocarbyloxy group and a hydroxy group are bonded to the polymerization terminal of butadiene rubber, more preferably the same polymerization active terminal. It has 1 or more (for example, 1 or 2).

In order to modify the active terminal of the butadiene rubber by reacting with a protected primary amine, the butadiene rubber is preferably one in which at least 10% of the polymer chains have a living property or a pseudo-living property. As the polymerization reaction having such living property, an organic alkali metal compound is used as an initiator, and the conjugated diene compound alone in an organic solvent, a reaction in which the conjugated diene compound and an aromatic vinyl compound are anionically polymerized, or an organic solvent is used. Among them, a reaction in which a conjugated diene compound alone using a catalyst containing a lanthanum series rare earth element compound or a conjugated diene compound and an aromatic vinyl compound are coordinated and anion-polymerized can be mentioned. The former is preferable because it can obtain a conjugated diene moiety having a higher vinyl bond content than the latter. Heat resistance can be improved by increasing the vinyl bond amount.

The organoalkali metal compound used as the initiator of anionic polymerization is preferably an organolithium compound. The organic lithium compound is not particularly limited, but hydrocarbyl lithium and lithium amide compounds are preferably used. When the former hydrocarbyl lithium is used, it has a hydrocarbyl group at the polymerization initiation terminal and the other terminal has polymerization activity. The butadiene rubber which is the part is obtained. When the latter lithium amide compound is used, a butadiene rubber having a nitrogen-containing group at the polymerization initiation terminal and the other terminal being a polymerization active site can be obtained.

The hydrocarbyllithium preferably has a hydrocarbyl group having 2 to 20 carbon atoms, and is, for example, ethyllithium, n-propyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, tert-octyllithium, n-decyl. Examples thereof include lithium, phenyllithium, 2-naphthyllithium, 2-butylphenyllithium, 4-phenylbutyllithium, cyclohexyllithium, cycloventyllithium, and reaction products of diisopropenylbenzene and butyllithium. Of these, n-butyllithium is particularly preferable.

On the other hand, examples of the lithium amide compound include lithium hexamethylene amide, lithium pyrrolidide, lithium piperidide, lithium heptamethyleneimide, lithium dodecamethyleneimide, lithium dimethylamide, lithium diethylamide, lithium dibutylamide, lithium dipropylamide and lithium di. Heptylamide, lithiumdihexylamide, lithium dioctylamide, lithiumdi-2-ethylhexylamide, lithiumdidecylamide, lithium-N-methylpyverazide, lithiumethylpropylamide, lithiumethylbutylamide, lithiumethylbenzylamide, lithiummethylphenethylamide, etc. Can be mentioned. Among these, cyclic lithium amides such as lithium hexamethyleneimide, lithium pyrrolidide, lithium piperidide, lithium heptamethyleneimide, and lithium dodecamethyleneimide are preferable from the viewpoint of the interaction effect with carbon black and the ability to initiate polymerization. In particular, lithium hexamethyleneimide and lithium pyrrolidide are suitable.
Generally, these lithium amide compounds are prepared in advance from a secondary amine and a lithium compound and can be used for polymerization, but they can also be prepared in a polymerization system (in-situ). The amount of the polymerization initiator used is preferably selected in the range of 0.2 to 20 mmol per 100 g of the monomer.

The method for producing butadiene rubber by anionic polymerization using the organolithium compound as a polymerization initiator is not particularly limited, and a conventionally known method can be used.
Specifically, in an organic solvent inert to the reaction, for example, a conjugated diene compound or a conjugated diene compound and an aromatic vinyl compound in a hydrocarbon-based solvent such as an aliphatic, alicyclic, or aromatic hydrocarbon compound, the above-mentioned A butadiene rubber having a desired active terminal can be obtained by anionically polymerizing a lithium compound as a polymerization initiator in the presence of a randomizer to be used, if desired.
Further, when an organic lithium compound is used as a polymerization initiator, not only a butadiene rubber having an active end but also a conjugated diene compound having an active end is compared with the case where a catalyst containing the above-mentioned lanthanum series rare earth element compound is used. And a copolymer of an aromatic vinyl compound can also be efficiently obtained.

The hydrocarbon solvent is preferably one having 3 to 8 carbon atoms, for example, propane, n-butene, 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 can be mentioned. These may be used alone or in combination of two or more.
The monomer concentration in the solvent is preferably 5 to 50% by mass, more preferably 10 to 30% by mass. When copolymerization is carried out using the conjugated diene compound and the aromatic vinyl compound, the content of the aromatic vinyl compound in the charged monomer mixture is preferably in the range of 55% by mass or less.

(Denaturant)
In the present invention, a primary amine-modified butadiene rubber is produced by reacting the active terminal of the butadiene rubber having the active terminal obtained as described above with a protected primary amine compound as a modifier. By reacting the protected secondary amine compound, a secondary amine-modified butadiene rubber can be produced. As the protected primary amine compound, an alkoxysilane compound having a protected primary amino group is suitable, and as the protected secondary amine compound, an alkoxysilane compound having a protected secondary amino group. Is preferable.

Examples of the alkoxysilane compound having a protected primary amino group used as a modifier for obtaining the amine-modified butadiene rubber include N, N-bis (trimethylsilyl) aminopropylmethyldimethoxysilane and 1-trimethylsilyl-2, 2-Dimethoxy-1-aza-2-silacyclopentane, N, N-bis (trimethylsilyl) aminopropyltrimethoxysilane, N, N-bis (trimethylsilyl) aminopropyltriethoxysilane, N, N-bis (trimethylsilyl) Aminopropylmethyldiethoxysilane, N, N-bis (trimethylsilyl) aminoethyltrimethoxysilane, N, N-bis (trimethylsilyl) aminoethyltriethoxysilane, N, N-bis (trimethylsilyl) aminoethylmethyldimethoxysilane and N , N-bis (trimethylsilyl) aminoethylmethyldiethoxysilane, etc., preferably N, N-bis (trimethylsilyl) aminopropylmethyldimethoxysilane, N, N-bis (trimethylsilyl) aminopropylmethyldiethoxy. Silane or 1-trimethylsilyl-2,2-dimethoxy-1-aza-2-silacyclopentane.

Examples of the modifier for obtaining the amine-modified butadiene rubber include N-methyl-N-trimethylsilylaminopropyl (methyl) dimethoxysilane, N-methyl-N-trimethylsilylaminopropyl (methyl) diethoxysilane, and N-trimethylsilyl. (Hexamethyleneimine-2-yl) propyl (methyl) dimethoxysilane, N-trimethylsilyl (hexamethyleneimin-2-yl) propyl (methyl) diethoxysilane, N-trimethylsilyl (pyrrolidin-2-yl) propyl (methyl) Dimethoxysilane, N-trimethylsilyl (pyrrolidin-2-yl) propyl (methyl) diethoxysilane, N-trimethylsilyl (piperidin-2-yl) propyl (methyl) dimethoxysilane, N-trimethylsilyl (piperidin-2-yl) propyl ( Methyl) diethoxysilane, N-trimethylsilyl (imidazol-2-yl) propyl (methyl) dimethoxysilane, N-trimethylsilyl (imidazol-2-yl) propyl (methyl) diethoxysilane, N-trimethylsilyl (4,5-dihydro) An alkoxysilane compound having a protected secondary amino group such as imidazole-5-yl) propyl (methyl) dimethoxysilane, N-trimethylsilyl (4,5-dihydroimidazol-5-yl) propyl (methyl) diethoxysilane; N- (1,3-dimethylbutylidene) -3- (triethoxysilyl) -1-propaneamine, N- (1-methylethylidene) -3- (triethoxysilyl) -1-propaneamine, N-ethylidene -3- (Triethoxysilyl) -1-propaneamine, N- (1-methylpropanol) -3- (Triethoxysilyl) -1-propaneamine, N- (4-N, N-dimethylaminobenzylidene) An alkoxysilane compound having an imino group such as -3- (triethoxysilyl) -1-propaneamine, N- (cyclohexylidene) -3- (triethoxysilyl) -1-propaneamine; 3-dimethylaminopropyl ( Triethoxy) silane, 3-dimethylaminopropyl (trimethoxy) silane, 3-diethylaminopropyl (triethoxy) silane, 3-diethylaminopropyl (trimethoxy) silane, 2-dimethylaminoethyl (triethoxy) silane, 2-dimethylaminoethyl (trimethoxy) Silane, 3-dimethylaminopropyl (diethoxy) methylsilane, 3 -Alkoxysilane compounds having an amino group such as dibutylaminopropyl (triethoxy) silane can also be mentioned.
These denaturants may be used alone or in combination of two or more. Further, this modifier may be a partial condensate.
Here, the partial condensate refers to a product in which a part (but not all) of SiOR (R is an alkyl group or the like) of the modifier is SiOSi bonded by condensation.

In the modification reaction with the modifier, the amount of the modifier used is preferably 0.5 to 200 mmol / kg · butadiene rubber. The amount used is more preferably 1 to 100 mmol / kg butadiene rubber, and particularly preferably 2 to 50 mmol / kg butadiene rubber. Here, the butadiene rubber means the mass of the butadiene rubber which does not contain additives such as an antiaging agent added at the time of production or after production. By setting the amount of the modifier used within the above range, the dispersibility of the filler, particularly carbon black, is excellent, and the fracture resistance and low heat generation of the side reinforcing rubber for run-flat tires are improved.
The method of adding the denaturant is not particularly limited, and examples thereof include a method of adding the denaturant all at once, a method of adding the denaturant in divided portions, a method of adding the denaturant continuously, and the like. preferable.
Further, the modifier can be bonded to any of the polymer main chain and side chain other than the polymerization start end and the polymerization end end, but the point that energy loss can be suppressed from the polymer end and the low heat generation property can be improved. Therefore, it is preferably introduced at the polymerization initiation terminal or the polymerization termination terminal.

(Condensation accelerator)
In the present invention, it is preferable to use a condensation accelerator in order to promote a condensation reaction involving an alkoxysilane compound having a protected primary amino group used as the above-mentioned modifier.
Examples of such a condensation accelerator include compounds containing a third amino group, or among Group 3, Group 4, Group 5, Group 12, Group 13, Group 14, and Group 15 of the periodic table (long-period type). An organic compound containing at least one element to which any of the above belongs can be used. Further, as a condensation accelerator, an alkoxide or carboxylic containing at least one metal selected from the group consisting of titanium (Ti), zirconium (Zr), bismuth (Bi), aluminum (Al), and tin (Sn). It is preferably a acid salt or an acetylacetonate complex salt.
The condensation accelerator used here can be added before the modification reaction, but is preferably added to the modification reaction system during and after the modification reaction. When added before the denaturation reaction, a direct reaction with the active terminal may occur and a hydrocarbyloxy group having a protected primary amino group at the active terminal may not be introduced.
The time for adding the condensation accelerator is usually 5 minutes to 5 hours after the start of the modification reaction, preferably 15 minutes to 1 hour after the start of the modification reaction.

Specific examples of the condensation accelerator include tetramethoxytitanium, tetraethoxytitanium, tetra-n-propoxytitanium, tetraisopropoxytitanium, tetra-n-butoxytitanium, tetra-n-butoxytitanium oligomer, and tetra-. sec-butoxytitanium, tetra-tert-butoxytitanium, tetra (2-ethylhexyl) titanium, bis (octanediolate) bis (2-ethylhexyl) titanium, tetra (octanediolate) titanium, titanium lactate, titanium dipropoxybis ( (Triethanolaminate), Titanium dibutoxybis (Triethanolaminate), Titanium tributoxystearate, Titanium tripropoxystearate, Titanium ethylhexyl diolate, Titanium tripropoxyacetylacetonate, Titanium dipropoxybis (acetylacetonate) , Titanium tripropoxyethyl acetoacetate, titanium propoxyacetyl acetoacetate bis (ethyl acetoacetate), titanium tributoxyacetyl acetonate, titanium dibutoxybis (acetyl acetonate), titanium tributoxyethyl acetoacetate, titanium butoxy acetyl acetoate bis (Ethylacetacetate), Titanium Tetrakiss (Acetylacetonate), Titanium Diacetylacetonate Bis (Ethylacetacetate), Bis (2-ethylhexanoate) Titanium Oxide, Bis (Laurate) Titanium Oxide, Bis (Naftenate) Titanium Oxide , Bis (steerate) titanium oxide, bis (oleate) titanium oxide, bis (linolate) titanium oxide, tetrakis (2-ethylhexanoate) titanium, tetrakis (laurate) titanium, tetrakis (naphthenate) titanium, tetrakis (steerate) ) Titanium, tetrakis (oleate) titanium, tetrakis (linolate) titanium, tetrakis (2-ethyl-1,3-hexanediorat) titanium and other titanium-containing compounds can be mentioned.

Also, for example, tris (2-ethylhexanoate) bismus, tris (laurate) bismus, tris (naphthenate) bismus, tris (steerate) bismus, tris (oleate) bismus, tris (linolate) bismus, tetraethoxyzirconium, Tetra-n-propoxyzirconium, tetraisopropoxyzirconium, tetra-n-butoxyzirconium, tetra-sec-butoxyzirconium, tetra-tert-butoxyzirconium, tetra (2-ethylhexyl) zirconium, zirconium tributoxystearate, zirconium tributoxy Acetylacetonate, zirconium dibutoxybis (acetylacetonate), zirconium tributoxyethylacetate, zirconium butoxyacetylacetonate bis (ethylacetate acetate), zirconium tetrakis (acetylacetonate), zirconium diacetylacetonate bis (ethylacetacetate) ), Bis (2-ethylhexanoate) zirconium oxide, Bis (laurate) zirconium oxide, Bis (naphthenate) zirconium oxide, Bis (steerate) zirconium oxide, Bis (oleate) zirconium oxide, Bis (linolate) zirconium oxide, Compounds containing bismuth or zirconium such as tetrakis (2-ethylhexanoate) zirconium, tetrakis (laurate) zirconium, tetrakis (naphthenate) zirconium, tetrakis (steerate) zirconium, tetrakis (oleate) zirconium, tetrakis (linolate) zirconium. Can be mentioned.

Also, for example, triethoxyaluminum, tri-n-propoxyaluminum, triisopropoxyaluminum, tri-n-butoxyaluminum, tri-sec-butoxyaluminum, tri-tert-butoxyaluminum, tri (2-1 ethylhexyl) aluminum, Aluminum dibutoxystearate, aluminum dibutoxyacetylacetonate, aluminum butoxybis (acetylacetonate), aluminum dibutoxyethylacetate, aluminumtris (acetylacetonate), aluminumtris (ethylacetacetate), tris (2-ethyl) Examples thereof include compounds containing aluminum such as hexanoate) aluminum, tris (laurate) aluminum, tris (naphthenate) aluminum, tris (steerate) aluminum, tris (oleate) aluminum, and tris (linolate) aluminum.

Among the above-mentioned condensation accelerators, a titanium compound is preferable, and a titanium metal alkoxide, a titanium metal carboxylate, or a titanium metal acetylacetonate complex salt is particularly preferable.
The amount of the condensation accelerator used is preferably 0.1 to 10 as the molar ratio of the number of moles of the compound to the total amount of hydrocarbyloxy groups present in the reaction system, preferably 0.5 to 5. Especially preferable. By setting the amount of the condensation accelerator to be used within the above range, the condensation reaction proceeds efficiently.
The condensation reaction time is usually about 5 minutes to 10 hours, preferably about 15 minutes to 5 hours. By setting the condensation reaction time within the above range, the condensation reaction can be completed smoothly.
The pressure of the reaction system during the condensation reaction is usually 0.01 to 20 MPa, preferably 0.05 to 10 MPa.

〔Carbon black〕
Carbon black has a specific surface area of 10 to 40 m ² / g by the nitrogen adsorption method, a dibutyl phthalate oil absorption amount (DBP oil absorption amount) of 100 to 180 mL / 100 g, and a compressed dibutyl phthalate oil absorption amount (24M4DBP) of 36 to 110 ml / 100 g. ..
In the present invention, the durability can be improved without impairing the low heat generation property of the side reinforcing rubber for the run-flat tire.
Specifically, since the specific surface area of the nitrogen adsorption method is 10 to 40 m ² / g, the balance between the reinforcing property of the side reinforcing rubber for run-flat tires and the low heat generation is excellent. Nitrogen adsorption method specific surface area is preferably 15 to 35 m ² / g, more preferably 17~32m ² / g.
The DBP oil absorption amount is used as an index showing the degree of development (structure) of the agglomerate structure of carbon black, and the larger the DBP oil absorption amount, the larger the agglomerates tend to be. When the DBP oil absorption of carbon black is 100 to 180 ml / 100 g, the balance between the reinforcing property of the side reinforcing rubber for run-flat tires and the low heat generation is excellent. The amount of DBP oil absorbed is preferably 105 to 160 ml / 100 g, more preferably 108 to 145 ml / 100 g.

The compressed dibutyl phthalate oil absorption is a value obtained by measuring the DBP oil absorption after repeatedly applying pressure at a pressure of 24,000 psi four times in accordance with ISO 6894. This compressed dibutyl phthalate oil absorption eliminates the DBP oil absorption due to the deformable / destructive structural form (secondary structure) caused by the so-called van der Waals force, and the structural form (primary) of the non-destructive true structure. It is an index for evaluating the skeletal structure specification of carbon black mainly composed of the primary structure, which is used when determining the DBP oil absorption amount based on the structure).
When the compressed dibutyl phthalate oil absorption amount is 36 to 110 ml / 100 g, the balance between the reinforcing property of the side reinforcing rubber for run-flat tires and the low heat generation is excellent. The amount of compressed dibutyl phthalate oil absorbed is preferably 50 to 95 ml / 100 g, more preferably 65 to 90 ml / 100 g.

In the above-mentioned equation (1), Dst is the most frequent value (nm) of the distribution curve of the equivalent diameter of Stokes, and the most frequent value of the aggregate distribution obtained by using the centrifugal sedimentation method according to the method described in JIS K6217-6. Refers to the size of the aggregate that gives. Let this Dst be the average diameter of the carbon black aggregates. Further, ΔD50 is the full width at half maximum (nm) of the distribution curve with respect to Dst, and is the width of the distribution when the frequency is half the height of the maximum point in the aggregate distribution curve obtained by the centrifugal sedimentation method.
From the viewpoint of facilitating the filling of the formula (1), the Dst of carbon black is preferably 210 to 310 nm, more preferably 220 to 300 nm. From the same viewpoint, the ΔD50 of carbon black is preferably 180 to 500 nm, more preferably 190 to 480 nm.

The content of carbon black in the rubber composition is 40 to 100 parts by mass with respect to 100 parts by mass of the rubber component from the viewpoint of the balance between the reinforcing property and the low heat generation of the side reinforcing rubber for run-flat tires. It is preferably 35 to 80 parts by mass, more preferably 40 to 69 parts by mass.

(Painting other than carbon black)
The rubber composition of the present invention may contain other reinforcing fillers as long as it does not deviate from the provisions of the present invention. For example, it may contain a reinforcing filler such as silica.

[Vulcanizing agent, vulcanization accelerator]
The rubber composition contains a vulcanizing agent. Sulfur is usually used as the vulcanizing agent.
The rubber composition also preferably contains a vulcanization accelerator, preferably a thiuram compound, in order to promote vulcanization of the rubber component.
The thiuram compound preferably has 4 or more carbon atoms in the side chain, more preferably 6 or more, and even more preferably 8 or more. When the number of carbon atoms in the side chain is 4 or more, the thiuram compound is excellently dispersed in the rubber composition, and a uniform crosslinked network is easily formed.
Examples of the thiuram compound having 4 or more side chain carbon atoms include tetrakis (2-ethylhexyl) thiuram disulfide, tetrakis (n-dodecyl) thiuram disulfide, tetrakis (benzyl) thiuram disulfide, tetrabutyl thiuram disulfide, and dipentamethylene thiuram tetra. Examples thereof include sulfide and tetrabenzyltiuram disulfide, and among them, tetrakis (2-ethylhexyl) thiuram disulfide is preferable.

The content of the sulfide accelerator in the rubber composition is preferably equal to or more than a mass part equal to the mass part of the sulfur used, preferably 2 times the mass part or more of the sulfur component, and is based on 100 parts by mass of the rubber component. It is preferably 4 to 30 parts by mass, and more preferably 7 to 20 parts by mass.
Further, in order to obtain a desired vulcanization torque and vulcanization rate, a vulcanization accelerator other than the thiuram compound, a vulcanization delaying agent and the like may be used in combination.
The rubber composition of the present invention has a Mooney viscosity (ML _{1 + 4} , 130 ° C.) of preferably 40 to 100, more preferably 50 to 90, and even more preferably 60 to 85. When the Mooney viscosity is in the above range, vulcanized rubber physical properties such as fracture resistance can be sufficiently obtained without impairing the manufacturing processability. The Mooney viscosity of the rubber composition conforms to JIS K 630-1: 2001 and can be measured using an L-shaped rotor.

In addition to the above components, the rubber composition of the present invention may contain a compounding agent that is blended and used in a normal rubber composition. For example, silane coupling agents, vulcanization accelerators, vulcanization retarders, softeners such as various process oils, zinc oxide, stearic acid, wax, anti-aging agents, compatibilizers, workability improvers, lubricants, etc. Examples thereof include various commonly blended compounding agents such as tackifiers, petroleum-based resins, ultraviolet absorbers, dispersants, and homogenizing agents.

As the anti-aging agent, known ones can be used, and the present invention is not particularly limited, and examples thereof include a phenol-based anti-aging agent, an imidazole-based anti-aging agent, and an amine-based anti-aging agent. The blending amount of these anti-aging agents is usually 0.5 to 10 parts by mass, preferably 1 to 5 parts by mass with respect to 100 parts by mass of the rubber component.

When obtaining the rubber composition, there is no particular limitation on the method of blending each of the above components, and all the component raw materials may be blended at once and kneaded, or each component may be blended in two or three stages. Kneading may be performed. A kneading machine such as a roll, an internal mixer, or a Banbury rotor can be used for kneading. Further, when molding into a sheet shape, a strip shape, or the like, a known molding machine such as an extrusion molding machine or a press machine may be used.

<Side reinforcement rubber for run-flat tires, run-flat tires>
The side reinforcing rubber for a run-flat tire of the present invention comprises the side reinforcing rubber composition for a run-flat tire of the present invention, and the run-flat tire of the present invention uses the side reinforcing rubber for a run-flat tire of the present invention. It will be used.
Hereinafter, an example of the structure of a run-flat tire having a side reinforcing rubber layer will be described with reference to FIG.
FIG. 1 is a schematic view showing a cross section of an embodiment of the run-flat tire of the present invention (hereinafter, may be simply referred to as a tire), and the side reinforcing rubber layer 8 and the like constituting the run-flat tire of the present invention are shown. The arrangement of each member will be described.

In FIG. 1, a preferred embodiment of the run-flat tire of the present invention is a troid-like chain between a pair of bead cores 1, 1'(1' is not shown), and both ends of the bead core 1 from the inside to the outside of the tire. A carcass layer 2 composed of at least one radial carcass ply that is wound up, a side rubber layer 3 that is arranged outside the side region of the carcass layer 2 in the tire axial direction to form an outer portion, and a crown region of the carcass layer 2. A tread rubber layer 4 arranged on the outer side in the tire radial direction to form a ground contact portion, a belt layer 5 arranged between the tread rubber layer 4 and the crown region of the carcass layer 2 to form a reinforcing belt, and the like. An inner liner 6 arranged on the entire inner surface of the tire of the carcass layer 2 to form an airtight film, a main body portion of the carcass layer 2 extending from one bead core 1 to the other bead core 1', and a winding wound around the bead core 1. At least one bead filler 7 arranged between the upper portion and the side region of the carcass layer from the side of the bead filler 7 to the shoulder area 10 between the carcass layer 2 and the inner liner 6. The tire includes a side reinforcing rubber layer 8 having a substantially crescent-shaped cross section along the tire rotation axis.
The run-flat tire of the present invention in which the side reinforcing rubber for a run-flat tire of the present invention is used for the side reinforcing rubber layer 8 of the tire is excellent in durability without impairing low heat generation.

The carcass layer 2 of the run-flat tire of the present invention is composed of at least one carcass ply, but the number of carcass plies may be two or more. Further, the reinforcing cords of the carcass ply can be arranged at an angle substantially 90 ° with respect to the tire circumferential direction, and the number of the reinforcing cords driven can be 35 to 65/50 mm. Further, a belt layer 5 composed of two first belt layers and a second belt layer is arranged outside the crown region of the carcass layer 2 in the tire radial direction, but the number of belt layers 5 is also limited to this. It is not something that can be done. As the first belt layer and the second belt layer, one in which a plurality of steel cords arranged in parallel in the tire width direction without being twisted are embedded in rubber can be used, for example. The first belt layer and the second belt layer may be arranged so as to intersect each other between the layers to form an intersecting belt.

Further, in the run-flat tire of the present invention, a belt reinforcing layer (not shown) may be arranged on the outer side of the belt layer 5 in the tire radial direction. Since the purpose of the reinforcing cord of the belt reinforcing layer is to secure the tensile rigidity in the tire circumferential direction, it is preferable to use a cord made of highly elastic organic fibers. Examples of the organic fiber cord include aromatic polyamide (aramid), polyethylene naphthalate (PEN), polyethylene terephthalate, rayon, zylon (registered trademark) (polyparaphenylene benzobisoxazole (PBO) fiber), aliphatic polyamide (nylon) and the like. Organic fiber cords and the like can be used.

Furthermore, in the run-flat tire of the present invention, a reinforcing member such as an insert or a flipper may be arranged outside the side reinforcing layer, although not shown. Here, the insert is a reinforcing material in which a plurality of highly elastic organic fiber cords arranged in the tire circumferential direction are arranged and rubber-coated from the bead cores 1, 1'to the side rubber layer 3 (not shown). The flipper is arranged between the main body portion of the carcass ply extending between the bead cores 1 or 1'and the folded portion folded around the bead core 1 or 1', and is arranged between the bead core 1 or 1'and the bead core 1 or 1'and the flipper thereof. A reinforcing material in which a plurality of highly elastic organic fiber cords are arranged and rubber-coated, which contains at least a part of a bead filler 7 arranged on the outer side in the tire radial direction. The angle of the insert and flipper is preferably 30-60 ° with respect to the circumferential direction.

Bead cores 1 and 1'are embedded in the pair of bead portions, respectively, and the carcass layer 2 is locked around the bead cores 1 and 1'by folding back from the inside to the outside of the tire. Also, it is not limited to this. For example, of the carcass plies constituting the carcass layer 2, at least one carcass ply is folded around the bead cores 1 and 1'from the inside to the outside in the tire width direction, and the folded end thereof is the belt layer 5. It may be a so-called envelope structure located between the carcass layer 2 and the crown portion. Furthermore, a tread pattern may be appropriately formed on the surface of the tread rubber layer 4, and an inner liner 6 may be formed on the innermost layer. In the run-flat tire of the present invention, as the gas to be filled in the tire, normal air or an inert gas such as nitrogen can be used.

(Manufacturing side reinforcing rubber for run-flat tires and run-flat tires)
A run-flat tire provided with a side-reinforcing rubber for a run-flat tire by using the side-reinforcing rubber composition for a run-flat tire of the present invention in the side-reinforcing rubber layer 8 and following the procedure of a normal manufacturing method for a run-flat tire. Is obtained.
That is, the rubber composition containing various chemicals is processed into each member at the stage of unvulcanization, and is pasted and molded on a tire molding machine by a usual method to form a raw tire. The raw tire is heated and pressurized in a vulcanizer to obtain a side reinforcing rubber for a run-flat tire and a run-flat tire.

<Examples 1 to 5, Comparative Examples 1 to 6>
[Preparation of rubber composition]
Each component was kneaded with the compounding composition shown in Table 1 below to prepare a rubber composition.
The modified butadiene rubber (modified BR) used for preparing the rubber composition was produced by the following method.

[Manufacture of primary amine-modified butadiene rubber (modified BR)]
(1) Production of Unmodified Polybutadiene Inject into a nitrogen-substituted 5L autoclave under nitrogen as a cyclohexane solution of 1.4 kg of cyclohexane, 250 g of 1,3-butadiene, and 2,2-ditetrahydrofurylpropane (0.285 mmol). After adding 2.85 mmol of n-butyllithium (BuLi) to this, polymerization was carried out for 4.5 hours in a warm water bath at 50 ° C. equipped with a stirrer. The reaction conversion rate of 1,3-butadiene was almost 100%. A part of this polymer solution is extracted with a methanol solution containing 1.3 g of 2,6-di-tert-butyl-p-cresol to stop the polymerization, and then desolvated by steam stripping and rolled at 110 ° C. To obtain polybutadiene before modification. As a result of measuring the microstructure (vinyl bond amount) of the obtained polybutadiene before modification by the infrared method (morero method), the vinyl bond amount was 30% by mass.

(2) Production of Primary Amine-Modified Polybutadiene Rubber The polymer solution obtained in (1) above was kept at a temperature of 50 ° C. without deactivating the polymerization catalyst, and N having a primary amino group protected. , N-bis (trimethylsilyl) aminopropylmethyldiethoxysilane 1129 mg (3.364 mmol) was added, and the modification reaction was carried out for 15 minutes.
Then, 8.11 g of tetrakis (2-ethyl-1,3-hexanediorat) titanium as a condensation accelerator was added, and the mixture was further stirred for 15 minutes.
Finally, 242 mg of silicon tetrachloride was added as a metal halogen compound to the polymer solution after the reaction, and 2,6-di-tert-butyl-p-cresol was added. Next, the primary amino group that was desolvated and protected by steam stripping was deprotected, and the rubber was dried by a mature roll adjusted to 110 ° C. to obtain a primary amine-modified polybutadiene rubber (modified BR). Obtained.
As a result of measuring the microstructure (vinyl bond amount) of the obtained modified polybutadiene by the infrared method (morero method), the vinyl bond amount was 30% by mass.

The details of each component other than the modified butadiene rubber (primary amine-modified polybutadiene rubber) used for preparing the rubber composition are as follows.
(1) Natural rubber (NR): RSS # 1
(2) Carbon black (Asahi # 65):
Asahi Carbon Co., Ltd. "Asahi # 65" [Nitrogen adsorption method specific surface area = 42 m ² / g, DBP oil absorption = 120 ml / 100 g, compressed dibutyl phthalate oil absorption = 85 ml / 100 g, Dst = 164 nm, ΔD50 = 134 nm]
(3) Carbon black (Asahi # 52):
Asahi Carbon Co., Ltd. "Asahi # 52" [Nitrogen adsorption method specific surface area = 28 m ² / g, DBP oil absorption = 128 ml / 100 g, compressed dibutyl phthalate oil absorption = 80 ml / 100 g, Dst = 231 nm, ΔD50 = 207 nm]
(4) Carbon Black (Orion S204):
"ECORAX S204" manufactured by Orion Engineered Carbons [Nitrogen adsorption method specific surface area = 19 m ² / g, DBP oil absorption = 138 ml / 100 g, compressed dibutyl phthalate oil absorption = 76 ml / 100 g, Dst = 246 nm, ΔD50 = 466 nm]
(5) Carbon black (Asahi # 50HG):
Asahi Carbon Co., Ltd. "Asahi # 50HG" [Nitrogen adsorption method specific surface area = 21m ² / g, DBP oil absorption = 112ml / 100g, compressed dibutyl phthalate oil absorption = 78ml / 100g, Dst = 298nm, ΔD50 = 287nm]
(6) Carbon Black (Asahi F200):
Asahi Carbon Co., Ltd. "Asahi F200" [Nitrogen adsorption method specific surface area = 53m ² / g, DBP oil absorption = 180ml / 100g, compressed dibutyl phthalate oil absorption = 104ml / 100g, Dst = 180nm, ΔD50 = 140nm]
(7) Carbon black (Asahi # 8):
Asahi Carbon Co., Ltd. "Asahi # 8" [Nitrogen adsorption method specific surface area = 16m ² / g, DBP oil absorption = 31ml / 100g, compressed dibutyl phthalate oil absorption = 31ml / 100g, Dst = 202nm, ΔD50 = 277nm]

(8) DCPD resin: Dicyclopentadiene petroleum resin, "Quinton 1105" manufactured by Zeon Corporation
(9) Stearic acid: "Stearic acid 50S" manufactured by Shin Nihon Rika Co., Ltd.
(10) Zinc Oxide: "No. 3 Zinc Oxide" manufactured by HakusuiTech Co., Ltd.
(11) Anti-aging agent (6C): N-phenyl-N'-(1,3-dimethylbutyl) -p-phenylenediamine, "Nocrack 6C" manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
(12) Vulcanization accelerator CZ: N-cyclohexyl-2-benzothiazolyl sulfeneamide, "Noxeller CZ-G" manufactured by Ouchi Shinko Chemical Industry Co., Ltd.
(13) Vulcanization accelerator TOT: Tetrakis (2-ethylhexyl) thiuram disulfide, "Noxeller TOT-N" manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.
(14) Sulfur: "Powdered sulfur" manufactured by Tsurumi Chemical Co., Ltd.

[Manufacturing and evaluation of run-flat tires]
Next, the obtained rubber composition was arranged on the side reinforcing rubber layer 8 shown in FIG. 1, and radial run-flat tires for passenger cars having tire sizes 205/65 R16 were manufactured according to a conventional method. The maximum thickness of the side reinforcing rubber layer of the tire was set to 12 mm.
The Mooney viscosity of the produced rubber composition was measured by the following method, and low heat generation and run-flat mileage were evaluated as the tire performance of the produced run-flat tire. The results are shown in Table 1.

1. 1. Mooney viscosity of rubber composition (ML _{1 + 4} , 130 ° C)
The Mooney viscosity of the rubber composition was measured at 130 ° C. using an L-shaped rotor in accordance with JIS K 630-1: 2001.

2. Evaluation of low heat generation With respect to the vulcanized rubber test piece cut out from the side reinforcing rubber layer of the manufactured run-flat tire, the loss tangent (tan δ) was measured at a temperature of 50 ° C. and strain 3 using a viscoelasticity measuring device (manufactured by Leometrics). %, The measurement was performed under the condition of a frequency of 15 Hz. The reciprocal of tan δ in Comparative Example 1 was set as 100 and displayed in exponential notation. The larger the index value, the better the low heat generation of the side reinforcing rubber and the run-flat tire provided with the side reinforcing rubber.

3. 3. Run-flat mileage The run-flat mileage was defined as the drum mileage until the tires could not run after running the drum (speed 80 km / h) without filling the internal pressure. It was expressed as an index with the run-flat mileage of the run-flat tire of Comparative Example 1 as 100. The larger the index, the better the durability of the side reinforcing rubber and the run-flat tire equipped with the side reinforcing rubber.

From Table 1, are the run-flat tires of the formulas (1) and (2) and the comparative example that do not satisfy the characteristics of carbon black excellent in durability because the run-flat mileage is not extended even if they are excellent in low heat generation? Comparative Example 6), even though it was excellent in durability, it was not excellent in low heat generation (Comparative Examples 1 to 5), and it was not possible to achieve both low heat generation and durability.
On the other hand, it can be seen that the run-flat tire of the embodiment can extend the run-flat mileage without impairing the low heat generation, and is excellent in durability.

1 bead core 2 carcass layer 3 side rubber layer 4 tread rubber layer 5 belt layer 6 inner liner 7 bead filler 8 side reinforcing rubber layer 10 shoulder area

Claims (9)

Rubber components including diene rubber and
Vulcanizer and
Nitrogen adsorption method Vulcanization accelerator containing carbon black having a specific surface area of 10 to 40 ^{m 2} / g, dibutyl phthalate oil absorption of 100 to 180 mL / 100 g, and compressed dibutyl phthalate oil absorption of 36 to 110 ml / 100 g, and a thiuram compound. And contains,
The interparticle distance S of the carbon black represented by the following formula (1) is 40 to 150 nm, and the carbon black represented by the following formula (2) and the occluder rubber occluded in the carbon black are coagulated. A side reinforcing rubber composition for a run-flat tire having a volume ratio φβ of an aggregate of 0.25 to 0.45.
The rubber component includes natural rubber and synthetic diene rubber.
The content of the natural rubber in the rubber component is 20 to 99% by mass.
The synthetic diene rubber contains a modified rubber having a modified functional group containing at least one selected from the group consisting of a tin atom, an oxygen atom and a nitrogen atom.
A side reinforcing rubber composition for a run-flat tire, wherein the content of the carbon black is 40 to 69 parts by mass with respect to 100 parts by mass of the rubber component.

[In the formula (1), Dst represents the most frequent value (nm) of the distribution curve having a diameter equivalent to Stokes, and ΔD50 represents the half width (nm) of the distribution curve with respect to the Dst. φβ represents the volume ratio of the agglomerates composed of the carbon black and the occluder rubber occluded in the carbon black, and is calculated by the following formula (2). ]

[In the formula (2), φ represents the ratio (VCB / VG) of the total volume VCB (ml) of carbon black to the total volume VG (ml) of the rubber composition, Vocc represents the volume of the occluder rubber, and Va. Represents the volume of carbon black aggregates. 24M4DBP represents the compressed dibutyl phthalate oil absorption (ml / 100 g) of carbon black. ] The side reinforcing rubber composition for a run-flat tire according to claim 1, wherein the synthetic diene rubber in the rubber component contains a polybutadiene rubber. The side reinforcing rubber composition for a run-flat tire according to claim 2, wherein the content of the polybutadiene rubber in the rubber component is 1 to 80% by mass. The side reinforcing rubber composition for a run-flat tire according to any one of claims 1 to 3, wherein the modified rubber contained in the synthetic diene rubber is a modified butadiene rubber. The side reinforcing rubber composition for a run-flat tire according to claim 4, wherein the modified butadiene rubber is a modified butadiene rubber having a modified functional group containing a nitrogen atom. The side reinforcing rubber composition for a run-flat tire according to claim 5, wherein the modified butadiene rubber having a modified functional group containing a nitrogen atom is an amine-modified butadiene rubber. The side reinforcing rubber composition for a run-flat tire according to any one of claims 1 to 6, wherein the thiuram compound has 4 or more side chain carbon atoms. A side reinforcing rubber for a run-flat tire using the side reinforcing rubber composition for a run-flat tire according to any one of claims 1 to 7. A run-flat tire using the side reinforcing rubber for a run-flat tire according to claim 8.

Images