JP2002036832A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire having both excellent performances of a run-flat durability and a rolling resistance while maintaining a good comfortability to ride. SOLUTION: In the pneumatic tire, a rubber composition constituting at least one of a tire side wall part reinforcing rubber and a bead filler is obtained by formulating (B) at least one compound selected from a compound represented by a general formula: R1-S-S-A-S-S-R2 (wherein A represents an alkylene group having 2-10 carbon atoms and R1 and R2 represent a monovalent organic group each independently including a nitrogen atom), a citraconimide compound and acrylates compound and (C) a reinforcing inorganic filler into (A) a rubber component containing 50% by weight or more of conjugated diene type polymer in which a vinyl-bonding amount in conjugated diene unit is 25% or more, a weight average molecular weight (Mw) is 200,000-900,000 and a molecular weight distribution (Mw/Mn) represented by a ratio of the weight average molecular weight and a number average molecular weight (Mn) is 1-4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly, to a rubber composition comprising a rubber composition containing a specific conjugated diene polymer and a bead filler and a side wall. The present invention relates to a pneumatic tire used for at least one of the following (hereinafter sometimes referred to as a side reinforcing layer), and more particularly to a pneumatic tire having improved run flat durability.

[0002]

2. Description of the Related Art Conventionally, in a tire, 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 a sidewall portion. However, in the rubber compositions used for these tires, in particular, the tire travels in a state where the internal pressure of the tire (hereinafter, referred to as the internal pressure) is reduced due to puncture of the tire, so-called run-flat travel, When the temperature is 200 ° C. or higher, a crosslinked portion formed by vulcanization or the like, or a polymer constituting the rubber component, tends to be cut. For this reason, when the elastic modulus of the rubber composition decreases, the deflection of the tire increases, heat is generated, and the breaking limit of the side reinforcing layer is reduced. As a result, the tire may fail relatively early. was there.

As one of means for delaying the process leading to such a failure as much as possible, the elastic modulus of the rubber composition to be used is made as large as possible by changing the compounding, or the loss tangent (tan δ) thereof is set as small as possible. Therefore, a method of suppressing heat generation of the rubber composition itself is known, but there is a limit in the conventional approach from the viewpoint of compounding,
In run-flat driving, the only way to ensure a certain durable distance is to increase the amount of side reinforcement layers and bead filler. As a result, during normal driving, riding comfort, noise level, weight, etc. The fact is that this is causing undesirable situations.

[0004]

Under such circumstances, the present invention maintains good ride comfort during normal running by devising a rubber component used for a bead filler and a sidewall reinforcing layer in such a situation. It is an object of the present invention to provide a pneumatic tire that is excellent in both rolling resistance and run flat durability while keeping the same.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, they have found that they contain a specific conjugated diene-based polymer, a specific compound, and a reinforcing inorganic filler. It has been found that a pneumatic tire using a rubber composition for at least one of a bead filler and a side reinforcing layer has a remarkably improved durability particularly in run-flat running. The present invention has been completed based on such findings.

That is, the present invention comprises: a pair of left and right bead cores; and a bead filler disposed radially outside of the bead core in the tire radial direction. The rubber composition constituting the bead filler is (A) The vinyl bond amount in the conjugated diene unit is 25% or more, and the weight average molecular weight (M
w) is from 200,000 to 900,000, and the molecular weight distribution (Mw /
50% by weight of a conjugated diene-based polymer having Mn) of 1 to 4
And (B) a general formula (I) R ¹ -SSSASR ² ... (I) (where A is an alkylene group having 2 to 10 carbon atoms, R ¹ and R
² independently represents a monovalent organic group containing a nitrogen atom. A pneumatic tire characterized by comprising at least one compound selected from the group consisting of a compound represented by the formula (1), a citraconic imide compound and an acrylate compound, and (C) a reinforcing inorganic filler. It is.

[0007] The present invention also provides a carcass layer, a tread portion disposed outside the carcass layer in the tire radial direction,
It comprises a pair of sidewall portions disposed on the left and right sides of the tread portion, and a rubber reinforcing layer disposed on the sidewall portion, and constitutes a rubber reinforcing layer disposed on the sidewall portion. The rubber composition has (A) a conjugated diene unit having a vinyl bond content of 25% or more, a weight average molecular weight (Mw) of 200,000 to 900,000, and a ratio represented by the ratio of the weight average molecular weight to the number average molecular weight (Mn). Conjugated diene polymer having a molecular weight distribution (Mw / Mn) of 1 to 4
A rubber component containing 0% by weight or more and (B) a general formula (I) R ¹ -SSSASR ² ... (I) wherein A is an alkylene having 2 to 10 carbon atoms Groups, R ¹ and R
² independently represents a monovalent organic group containing a nitrogen atom. A pneumatic tire characterized by comprising at least one compound selected from the group consisting of a compound represented by the formula (1), a citraconic imide compound and an acrylate compound, and (C) a reinforcing inorganic filler. It is.

Further, the present invention provides a pair of left and right bead cores, a bead filler and a carcass layer disposed outside the bead core in the tire radial direction, and a tread portion disposed outside the carcass layer in the tire radial direction. It comprises a pair of sidewall portions disposed on the left and right sides of the tread portion, and a rubber reinforcing layer disposed on the sidewall portions, and is disposed on the rubber composition and the sidewall portion constituting the bead filler. The rubber composition constituting the provided rubber reinforcing layer has (A) a conjugated diene unit having a vinyl bond amount of 25% or more and a weight average molecular weight (Mw) of 200,000 to 9%.
And the weight average molecular weight and the number average molecular weight (M
n) a molecular weight distribution (Mw / Mn) represented by a ratio of 1 to 4
(B) a rubber component containing at least 50% by weight of a conjugated diene polymer; and (B) R ¹ -SSSASR ² ... (I) Is an alkylene group having 2 to 10 carbon atoms, R ¹ and R
² independently represents a monovalent organic group containing a nitrogen atom. A pneumatic tire characterized by comprising at least one compound selected from the group consisting of a compound represented by the formula (1), a citraconic imide compound and an acrylate compound, and (C) a reinforcing inorganic filler. It is.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, 50% by weight of a conjugated diene polymer having a vinyl bond content, a weight average molecular weight (Mw) and a molecular weight distribution (Mw / Mn) in the conjugated diene unit limited to the above specific ranges. The rubber component (A) contained above, at least one compound (B) selected from the compound of the general formula (I), citraconic imide compound and acrylate compound, and (C) a reinforcing inorganic filler were blended. In the tire using the rubber composition for at least one of the bead filler and the side reinforcing layer, the effect of suppressing the decrease in the elastic modulus due to the temperature rise of the rubber composition is remarkable, so that the increase in the deflection of the tire due to run flat running is suppressed. As a result, run flat durability can be improved.

In the present invention, the conjugated diene-based polymer as the component (A) needs to have a vinyl bond content in the conjugated diene unit of 25% or more. If the vinyl bond amount is less than 25%, the decrease in elastic modulus due to sulfur crosslinking cleavage at a high temperature of 150 ° C. or more becomes dominant, so that the effect of suppressing the decrease in elastic modulus due to a rise in temperature cannot be sufficiently expected.
In this respect, the vinyl bond amount is preferably 30% or more, and more preferably 35% or more. In particular, it is preferably 40 to 60%. Further, the weight average molecular weight (M
w) needs to be 200,000 to 900,000. If it is less than 200,000, the tensile properties and rolling resistance of the rubber composition tend to be poor, and if it exceeds 900,000, the processability tends to be poor. In this respect, Mw is preferably from 300,000 to 800,000, particularly from 300,000 to 800,000.
700,000 is preferred.

Further, the molecular weight distribution of the polymer (Mw /
Mn) needs to be 1 to 4. Mw
If / Mn exceeds 4, the heat build-up tends to decrease, and it is difficult to maintain the elastic modulus in a temperature region of 150 ° C or higher. In this respect, Mw / Mn is preferably 1 to 3.
The conjugated diene-based polymer in the present invention is preferably a conjugated diene homopolymer, a conjugated diene copolymer or a conjugated diene-aromatic vinyl copolymer, and also includes a modified polymer thereof as described later. . Here, as the conjugated diene monomer, for example, 1,3-butadiene, 1,3
-Pentadiene, 1,3-hexadiene and the like, among which 1,3-butadiene is preferable. Examples of the aromatic vinyl monomer used for copolymerization with a conjugated diene monomer include, for example, styrene, α-methylstyrene,
-Vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, 4-cyclohexylstyrene, 2,2,6-tolylstyrene, and the like;
Among them, styrene is preferred.

The conjugated diene polymer can be produced by various methods, and the polymerization method may be either a batch polymerization method or a continuous polymerization method. Preferred manufacturing methods are as follows. That is, it is obtained by polymerizing a monomer containing a conjugated diene in an inert solvent, preferably a hydrocarbon solvent, in the presence of an initiator such as an organic metal, preferably an organic lithium compound initiator. The hydrocarbon solvent is not particularly limited, but includes, for example, n-pentane, n-hexane, n-heptane, cyclohexane, benzene, toluene and the like. Preferred solvents are cyclohexane and n-hexane. These hydrocarbon solvents may be used alone or as a mixture of two or more.

The organic lithium used as the initiator is preferably a hydrocarbon lithium compound having at least one lithium atom bonded and having 2 to 20 carbon atoms, such as n-butyllithium, ethyllithium and n-butyllithium.
-Propyl lithium, tert-octyl lithium, phenyl lithium and the like, and preferred is n-butyl lithium. These organic lithium initiators may be used alone or in combination of two or more. The amount of vinyl bond is ditetrahydrofurylpropane, tetrahydrofuran, diethyl ether, dimethoxybenzene, dimethoxyethane, ethylene glycol dibutyl ether, triethylamine, pyridine, N, N, N ',
It can be changed as appropriate by adding an appropriate amount of an ether such as N′-tetramethylethylenediamine, dipiperidinoethane and / or a tertiary amine compound to the polymerization system.

Further, the conjugated diene-based polymer used in the present invention also includes a modified polymer. In particular, in the case of a polymer containing a silicon atom in the molecule, the polymer contains a reinforcing inorganic filler (C). Is preferably used because of its high affinity. The modified polymer having a silicon atom introduced into the molecular chain,
It is preferably used because it suppresses a decrease in elastic modulus due to a rise in temperature, and particularly has a large effect of improving low heat build-up in a rubber composition containing the reinforcing inorganic filler and carbon black. Further, as the modified polymer, those having a branched structure obtained by using a polyfunctional modifier are particularly preferable.

The above-mentioned modified polymer is produced by a known method, and is usually obtained by initiating polymerization with an organolithium initiator and adding various modifiers to a solution of a polymer having a lithium active terminal. Fairness 6-891
No. 83, JP-A-11-29659, etc.). In particular, a modified polymer having a silicon atom introduced into a molecular chain is introduced by a terminal modifier such as alkoxysilane or aminoalkoxysilane. Examples of such an introducing modifier include, for example, alkoxy such as methyltriethoxysilane, tetraethoxysilane (TEOS), 3-glycidoxypropyltriethoxysilane (GPEOS), and 3-glycidoxypropyltrimethoxysilane (GPMOS). Silane, 1- {3- (triethoxysilyl) propyl} -4,5-dihydroimidazole (TEOSD
I), N- (1,3-dimethylbutylidene) -3- (triethoxysilyl) -1-propanamine (Silaace S340: trademark, manufactured by Chisso Corporation), dimethylaminopropyltriethoxysilane (DMAPTE), etc. Aminoalkoxysilane. The content of the conjugated diene-based polymer containing a silicon atom in the molecule is preferably 50% by weight or more of the total amount of the conjugated diene-based polymer.
Further, the conjugated diene-based polymer in the present invention is preferably a polybutadiene having the above specific properties, and in the rubber component,
The polybutadiene preferably contains at least 60% by weight.

The rubber composition of the present invention must contain the above-mentioned polymer in a rubber component in an amount of 50% by weight or more. If the amount is less than 50% by weight, a decrease in rubber elasticity due to a rise in temperature may not be suppressed. From this viewpoint, the polymer is preferably contained in an amount of 60% by weight or more, more preferably 80% by weight or more. In the rubber composition of the present invention, other rubber components that can be mixed with the polymer are not particularly limited. For example, natural rubber, polyisoprene synthetic rubber (IR); cis-1,4-polybutadiene rubber ( B
R), styrene-butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR) and the like. These rubbers may be used in combination of two or more.

Next, in the rubber composition used in the present invention, in order to improve heat resistance, (B) component
Formula (I) R ¹ -SSSASR ² (I) wherein A is an alkylene group having 2 to 10 carbon atoms, R ¹ and R
² independently represents a monovalent organic group containing a nitrogen atom. ), At least one compound selected from citraconic imide compounds and acrylate compounds. Hereinafter, the details of each of these compounds will be described. The compound in the component (B) is a compound represented by the general formula (I) R ¹ -SSA-S-S-R ² ... (I).

In the general formula (I), A represents 2 carbon atoms.
And 10 to 10 alkylene groups, which may be linear, branched or cyclic, but are preferably linear alkylene groups. Examples of the linear alkylene group having 2 to 10 carbon atoms include an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, a heptamethylene group, an octamethylene group, and a decamethylene group. Among them, a hexamethylene group is particularly preferable from the viewpoint of the effect. On the other hand, each of R ¹ and R ² represents a monovalent organic group containing a nitrogen atom, and is preferably a monovalent organic group containing at least one aromatic ring and containing a nitrogen atom. Those containing a bonding group represented by = NC (= S)-bonded to a dithio group are preferable. R ¹ and R ² may be the same or different from each other, but are preferably the same from the viewpoint of easy production. As the compound represented by the general formula (I), for example, a compound represented by the general formula (Ia)

[0019]

Embedded image

Α, ω-bis (N, N′-dihydrocarbylthiocarbamoyldithio) alkane represented by the following formula: In the general formula (Ia), R ^{3 to} R ⁶ each represent an alkyl group, an aryl group or an aralkyl group, and at least one of R ³ and R ⁴ and at least one of R ⁵ and R ⁶ are aryl. And n is an integer of 2 to 10.

Here, the alkyl group has 1 to 1 carbon atoms.
Twenty are preferable, and any of linear, branched and cyclic shapes may be used. Examples of such alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-
Butyl, tert-butyl, various pentyl, various hexyl, various octyl, various decyl, various dodecyl, various tetradecyl, various hexadecyl, various octadecyl, cyclopentyl, cyclohexyl, cyclooctyl, etc. Is mentioned. The aryl group preferably has 6 to 20 carbon atoms, and may have a suitable substituent such as a lower alkyl group on the ring. Examples of such aryl groups include phenyl, tolyl, xylyl, naphthyl, methylnaphthyl and the like. The aralkyl group preferably has 7 to 20 carbon atoms, and may have a suitable substituent such as a lower alkyl group on the ring. Examples of such aralkyl groups include benzyl, methylbenzyl, dimethylbenzyl, phenethyl, methylphenethyl, dimethylphenethyl, naphthylmethyl, (methylnaphthyl) methyl, (dimethylnaphthyl) methyl, Naphthylethyl group, (methylnaphthyl)
Examples include an ethyl group and a (dimethylnaphthyl) ethyl group.

It is preferable that all of R ^{3 to} R ⁶ are the above-mentioned aryl groups or aralkyl groups, and it is particularly preferable that all of them are benzyl groups from the viewpoints of prevention of heat aging and ease of production. is there. Examples of such compounds include 1,2-bis (N, N′-dibenzylthiocarbamoyldithio) ethane; 1,3-bis (N, N′-dibenzylthiocarbamoyldithio) propane; -Bis (N, N'-dibenzylthiocarbamoyldithio) butane; 1,5-bis (N, N'-dibenzylthiocarbamoyldithio) pentane; 1,6-bis (N, N'-dibenzylthiocarbamoyl) 1,7-bis (N, N′-dibenzylthiocarbamoyldithio) heptane; 1,8-bis (N, N′-dibenzylthiocarbamoyldithio) octane; 1,9-bis (N, N'-
Dibenzylthiocarbamoyldithio) nonane; 1,10
-Bis (N, N'-dibenzylthiocarbamoyldithio) decane. Among these, 1,6-bis (N, N′-dibenzylthiocarbamoyldithio) hexane is particularly preferable from the viewpoint of the effect.

The compound represented by the general formula (I) exhibits an effect of improving the heat resistance of the rubber composition, but its effect is to increase the heat stability in parallel with the crosslinking at high temperatures. It is thought to be due to the efficient formation of monosulfide bridges. As the citraconic imide compound as the component (B) used in the rubber composition used in the present invention, biscitraconic imides are preferable from the viewpoint of the effect. (II)

[0024]

Embedded image

Compounds represented by the following formulas can be preferably mentioned. In the general formula (II), Ar represents an arylene group, and the arylene group is preferably an arylene group having 6 to 20 carbon atoms having or not having a substituent on a ring. The substituent is not particularly limited as long as it has no influence on vulcanization and is stable at a high temperature of 170 ° C. or higher. For example, a lower alkyl group or alkoxyl group, a halogen atom, a nitro group, And a cyano group. Examples of the arylene group include a phenylene group and a naphthylene group, and a phenylene group is particularly preferable. On the other hand, Q ¹ and Q ² each represent an alkylene group having 1 to 4 carbon atoms, and the alkylene group may be linear or branched. Examples of such an alkylene group include a methylene group, an ethylene group, a propylene group, and a butylene group. Q ¹ and Q
² may be the same or different, but are preferably the same from the viewpoint of ease of production and the like. Examples of the compound represented by the general formula (II) include 1,2-bis (citraconimidomethyl) benzene; 1,3-bis (citraconimidomethyl) benzene; 1,4-bis (citraconimidomethyl) Benzene; 1,6-bis (citraconimidomethyl) benzene; 2,3-bis (citraconimidomethyl) toluene; 2,4-bis (citraconimidomethyl) toluene; 2,5-bis (citraconimidomethyl) toluene; Examples thereof include 2,6-bis (citraconimidomethyl) toluene and bis (citraconimidoethyl) compounds corresponding thereto. Among these,
From the viewpoint of the effect, 1,6-bis (citraconimidomethyl) benzene is particularly preferred.

The citraconimide compound (B) exhibits an effect of improving the heat resistance of the rubber composition, but its effect is to react with the conjugated CＣC in the main chain generated at the time of crosslinking cleavage at a high temperature. However, it is considered that this is due to the early generation of CC crosslinks. Further, as the acrylate as the component (B), a polyhydric ester of a polyhydric alcohol and acrylic acid, or a polyhydric ester of a polyhydric alcohol and acrylic acid and another carboxylic acid is preferable from the viewpoint of the effect, As the polyhydric ester, for example, a compound represented by the general formula (III)

[0027]

Embedded image

Compounds represented by the following formulas can be preferably mentioned. In the general formula (III), A represents a residue excluding a hydroxyl group of a (p + q) -valent polyhydric alcohol, and R represents a hydrogen atom or an acyl group other than an acryloyl group. The acyl group is not particularly limited, but is preferably a saturated or unsaturated aliphatic acyl group having 2 to 20 carbon atoms. p represents an integer of 2 to 10 and q represents an integer of 0 to 8, where p + q = 2 to 10. This general formula (II
Among the compounds represented by I), those in which p is an integer of 3 to 6 and q is an integer of 0 to 3 and p + q = 3 to 6 are preferable in terms of effect. General formula (IV) A- (OH) _{p + q} (IV) used for forming the acrylate represented by the general formula (III) (where A and p, q are the same as described above) )), Tri- to hexa-hydric alcohols are preferred, such as glycerin,
Trimethylolethane, trimethylolpropane, diglycerin, pentaerythritol, dipentaerythritol, sorbitol and the like. The general formula (II
As the compound represented by I), from the viewpoint of effect, a polyvalent ester of dipentaerythritol having 3 to 6 acryloyl groups in one molecule and acrylic acid and 3 to 5 acryloyl groups in one molecule are used. Preferred is an acyl group-modified dipentaerythritol acrylate. Such compounds are commercially available as shown below.
For example, the expression

[0029]

Embedded image The compound represented by a mixture of a = 5, b = 1 and a = 6, b = 0) is referred to as “KAYARAD DP
HA ”(trademark, manufactured by Nippon Kayaku Co., Ltd.)

[0030]

Embedded image (R ⁷ represents an alkynyl group.) When c = 5 and d = 1, the compound represented by “K
AYARAD D-310 ”[trademark, Nippon Kayaku Co., Ltd.
KAYARAD when c = 3, d = 3
D-330 "(trademark, manufactured by Nippon Kayaku Co., Ltd.). The acrylates of the component (B) include:
It has the effect of improving the heat resistance of the rubber composition, but its action is due to the conjugated C
= C, which is believed to be due to the effective formation of CC bridges.

The compounding amount of the component (B) is the same as that of the component (A).
0.5 parts by weight based on 100 parts by weight of the rubber component
It is selected in the range of ２０20 parts by weight. If the amount is less than 0.5 parts by weight, the effect of preventing heat aging cannot be sufficiently obtained, and the desired effect of improving heat resistance may not be exhibited. Meanwhile, 2
If the amount exceeds 0 parts by weight, the effect is not so much improved in spite of the amount, which is rather economically disadvantageous and causes other physical properties of the obtained rubber composition to deteriorate. In consideration of the effect of preventing heat aging, other physical properties and economics of the rubber composition, the more preferable compounding amount of the component (B) is 0.7
To 15 parts by weight, particularly preferably 1.0 to 10 parts by weight.

In the present invention, if desired, another heat aging inhibitor can be appropriately used in combination with the compound of the above-mentioned component (B). Other heat aging inhibitors include:
For example, sodium 1,6-hexamethylenedithiosulfate
Examples include dihydrate and compounds having two or more ester groups in one molecule. Here, the compound having two or more ester groups in one molecule is not particularly limited,
Preference is given to acrylates or methacrylates, in particular polyhydric esters of polyhydric alcohols with acrylic acid or methacrylic acid. Examples of the polyhydric alcohol include alkylene glycols such as ethylene glycol, propylene glycol, butylene glycol, pentanediol, and hexanediol and multimers thereof, and further, methylol-substituted products thereof, pentaerythritols, and alkylene oxide adducts of polyhydric alcohols. And polyesters or oligoesters having two or more alcoholic hydroxyl groups. Of these, particularly preferred are methylol-substituted alkylene glycols and multimers thereof.

Specific examples of the compound having two or more ester groups in one molecule include 1,3-butylene glycol diacrylate; 1,5-pentanediol diacrylate; neopentyl glycol diacrylate;
Hexanediol diacrylate; diethylene glycol diacrylate; triethylene glycol diacrylate; tetraethylene glycol diacrylate; polyethylene glycol diacrylate; polypropylene glycol diacrylate; pentaerythritol triacrylate; trimethylolpropane triacrylate; pentaerythritol tetraacrylate; Erythritol hexaacrylate; dipentaerythritol pentaacrylate; oligoester polyacrylate; dipropylene glycol dimethacrylate;
Trimethylolethane trimethacrylate; trimethylolpropane trimethacrylate; dipentaerythritol pentamethacrylate; dipentaerythritol trimethacrylate; and the like, with dipentaerythritol pentamethacrylate; dipentaerythritol trimethacrylate; Propane trimethacrylate.

The above-mentioned sodium 1,6-hexamethylenedithiosulfate dihydrate has an effect of suppressing the cross-linkage between polymer molecules constituting the rubber component. On the other hand, the action of the compound having two or more ester groups in one molecule is considered as follows. When the temperature of the rubber composition becomes 170 ° C. or higher, the degradation of the rubber starts, and the cross-linking points and the breaking of the polymer chains start to occur. As a result, heat generation is suppressed even at a high temperature.

Further, in the present invention, the component (C)
It is necessary to mix reinforcing inorganic fillers.
The reinforcing inorganic filler used in the present invention must be porous.
Are preferable, and the BET type nitrogen adsorption specific surface area is 50 to 40.
0m^Two/ G is more preferable. This reinforcing property
The following general formula mM^One・ XSiO_y・ ZH_TwoO (where M^OneIs selected from Al, Mg, Ti and Ca
At least one metal, metal oxide or metal water
M is 1 to 5, x is 0 to 10, and y is 2 to 2
5, z is an integer of 0 to 10. )
Preferably, for example, alumina (Al
_TwoO_Three), Aluminum hydroxide [Al (OH)_Three],water
Magnesium oxide [Mg (OH)_Two], Magnesium oxide
MgO_Two, Talc (3MgO.4SiO_Two・ H
_TwoO), Attapulgite (5MgO · 8SiO)_Two・ 9
H_TwoO), titanium white (TiO_Two), Titanium black (TiO
_2n-1: N is a positive integer), calcium oxide (CaO), water
Calcium oxide [Ca (OH)_Two],Aluminum oxide
Magnesium (MgO · Al_TwoO_Three), Clay (Al_Two
O_Three・ 2SiO _Two), Kaolin (Al_TwoO_Three・ 2SiO
_Two・ 2H_TwoO), pyrophyllite (Al_TwoO_Three・ 4S
iO_Two・ H_TwoO), bentonite (Al_TwoO_Three・ 4Si
O_Two・ 2H_TwoO), aluminum silicate (Al_TwoSiO
_Five, Al_Four・ 3SiO_Four・ 5H_TwoO, etc.), magnesisilicate
Cium (Mg_TwoSiO_Four, Mg_TwoSiO_ThreeEtc.), silicic acid
Calcium (Ca_TwoSiO_FourEtc.), aluminum silicate
Calcium (Al_TwoO_Three・ CaO ・ 2SiO_TwoEtc.) and
Magnesium calcium silicate (CaMgSiO_Four)etc
Is mentioned. In addition, aluminum hydroxide includes aluminum
Na hydrate (Al_TwoO _Three・ 3H_TwoO) is also included. these
The inorganic compounds of the above may be used alone or as a mixture of two or more.
May be used. Among them, especially silica, hydroxyl
Aluminum oxide, aluminum oxide, calcium carbonate,
Magnesium carbonate, clay and zeolites are preferred.
Further, the reinforcing inorganic filler and carbon black are used together.
It is preferred to use

In the rubber composition containing the conjugated diene polymer according to the present invention, in addition to the above components, vulcanizing agents such as sulfur and peroxide, vulcanization accelerators, Various compounding agents such as an antioxidant, a softener, a reinforcing filler, and an inorganic filler can be appropriately contained. Further, the rubber composition of the present invention further includes particles of various materials,
It may be a composite with fiber, cloth and the like. The pneumatic tire of the present invention can be manufactured by a conventional method by applying the rubber composition to at least one of a bead filler and a rubber reinforcing layer provided on a sidewall portion.

Next, regarding the pneumatic tire of the present invention,
This will be described with reference to the accompanying drawings. FIG. 1 is a partial sectional view of the left half of an example of the pneumatic tire of the present invention. The pneumatic tire 1 includes a pair of left and right ring-shaped bead cores 4 and a radially outer portion of the bead cores 4. A bead filler 5, a carcass layer 2 composed of at least one ply in which a plurality of parallel cords are embedded in a covering rubber, and a belt layer 3 disposed outside the carcass layer 2 in a tire radial direction. A tread portion 8 disposed outside the belt layer 3 in the tire radial direction; a pair of sidewall portions 6 disposed on the left and right sides of the tread portion 8; and a rubber disposed on the sidewall portion 6. A reinforcing layer 7 is provided.

The carcass layer 2 is a folded carcass ply 2
a and the down carcass ply 2b, and both end portions of the folded carcass ply 2a are folded around the bead core 4 to form a folded end portion. The bead filler 5 is located between the folded carcass ply 2a and its folded end.
b is the side wall portion 6 and the folded carcass ply 2
It is arranged between the folded end of FIG. The rubber reinforcing layer 7 is disposed on the inner peripheral surface of the sidewall portion of the folded carcass ply 2a. The rubber of the rubber reinforcing layer 7 that reinforces the sidewall portion 6 may be a composite with organic fibers, inorganic particles, or the like, and its cross-sectional shape is not particularly limited as long as it has a side reinforcing function. .

In the pneumatic tire of the present invention, at least one of the bead filler 5 and the rubber reinforcing layer 7 is formed by using the rubber composition containing the conjugated diene polymer. In the pneumatic tire of the present invention, the ride comfort and the noise level do not substantially deteriorate due to the increase in the elastic modulus during normal running. Further, even if the temperature of the rubber composition becomes 170 ° C. or more due to a large deformation due to a puncture of the tire or the like, a decrease in the elastic modulus is suppressed, so that heat generation at a high temperature is suppressed. Therefore, the pneumatic tire of the present invention using this rubber composition for the bead core or the rubber reinforcing layer of the side wall portion has a significantly improved durability, particularly in run-flat running, and can significantly extend the running distance. .

[0040]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Various measurements were obtained according to the following methods. (1) Microstructure of Polymer The amount of vinyl bond (1,2-bond) in the conjugated diene unit was determined by an infrared method (Morello method). (2) Characteristics such as dynamic storage elastic modulus (E ') From a 2 mm thick slab sheet obtained by vulcanizing a rubber composition at 160 ° C. for 12 minutes, a width of 5 mm and a length of 4
A sheet of 0 mm was cut out and used as a sample. Using a spectrometer manufactured by Ueshima Seisakusho Co., Ltd., the distance between the chucks was 10 mm, the initial strain was 200 micrometers (microns), the dynamic strain was 1%, the frequency was 52 Hz, the measurement start temperature was 25 ° C., and the heating rate was 3 ° C. / Min, measurement end temperature 250
The dynamic storage modulus was measured under the measurement conditions of ° C. Also, 5
The ratio of the minimum value of the dynamic storage elastic modulus in the temperature range of 200 to 250 ° C. to the dynamic storage elastic modulus of 0 ° C. was indicated by an index. The larger the index is, the smaller the decrease of the dynamic storage modulus due to the high temperature is.

(3) Ride Comfort Each prototype tire is mounted on a passenger car, and a ride comfort feeling test is conducted by two specialized drivers, and 1 to 10
And the average was calculated. The larger the value, the better the ride comfort. (4) Run Flat Durability Each prototype tire is rim-assembled at normal pressure, filled with an internal pressure of 200 kPa, and then left at room temperature of 38 ° C. for 24 hours. 14kN
(524 kgf), a speed of 89 km / h, and a room temperature of 38 ° C. A drum running test was performed. The running distance up to the occurrence of a failure at this time is defined as run-flat durability, and Examples 1 and 2 and Comparative Example 2 are represented by an index when Comparative Example 1 is set to 100, and Examples 3 to 10 and Comparative Example 4 are compared. Example 3
Is represented by an index with 100 as an index. The larger the index, the better the run flat durability. (5) Rolling Resistance The rolling resistance was measured by the coasting method. The tire internal pressure was 1.7 kg / cm ² , the load was JIS 100% load, and the coasting start speed was 100 km / hr. 2 and Comparative Example 2 were represented by an index with Comparative Example 1 being 100, and Examples 3 to 10 and Comparative Example 4 were represented by an index with Comparative Example 3 being 100. The lower the index, the lower the rolling resistance.

Production Examples 1 to 3 (Polymers A to C) 3 kg of cyclohexane, 500 g of butadiene monomer, and 0.05 mmol of ditetrahydrofuryl were placed in an 8 liter pressure-resistant reactor equipped with a dried and nitrogen-substituted temperature-controlled jacket. Inject propane (DTHFP) and add 4mmo
After adding 1 l of n-butyllithium (BuLi), 40
Polymerization was carried out at an onset temperature of 1 ° C. for 1 hour. The polymerization was performed under elevated temperature conditions, and the jacket temperature was adjusted so that the final temperature did not exceed 75 ° C. The polymerization system was uniformly transparent from the start to the end of the polymerization without any precipitation. The polymerization conversion rate is
It was almost 100%. Thereafter, 2,6-di-t is added to the polymerization system.
The reaction was stopped by adding 0.5 ml of a 5% solution of -butyl-p-cresol (BHT) in isopropanol, and the polymer was dried in a conventional manner to obtain a polymer A. Further, in the process for producing the polymer A, the polymer B was prepared in the same manner as above except that the amount of DTHFP was changed to that shown in Table 1.
And C were obtained. Microstructure (vinyl bond amount), molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the obtained polymers A to C were measured. Table 1 shows the results.

Production Examples 4 to 8 (Polymers D to H) A dried, nitrogen-substituted, 8 liter pressure-resistant reactor equipped with a temperature-controlled jacket was charged with 3 kg of cyclohexane, 500 g of butadiene monomer, and 1.6 mmol of ditetrahydrofuryl. Inject propane (DTHFP) and add 5 mmol
Of n-butyl lithium (BuLi) at 40 ° C.
At the starting temperature of 1 hour. The polymerization was performed under elevated temperature conditions, and the jacket temperature was adjusted so that the final temperature did not exceed 75 ° C. The polymerization system was uniformly transparent from the start to the end of the polymerization without any precipitation. The polymerization conversion was almost 100%. To this polymerization system, 4.3 ml of tetraethoxysilane (TEOS; 1M cyclohexane solution) was added as a terminal modifier, followed by a modification reaction for 30 minutes. Thereafter, 2,6-di-t-butyl- was added to the polymerization system.
0.5 ml of a 5% solution of p-cresol (BHT) in isopropanol was added to stop the reaction, and the polymer was dried in a conventional manner to obtain a weight D. Polymers E to H were obtained in the same manner as described above, except that the amount of BuLi and the type and amount of the terminal modifier were changed to those shown in Table 1 in the method for producing weight D. Microstructure (vinyl bond amount), molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the obtained polymers D to H were measured. Table 1 shows the results.

Production Example 9 (Polymer I) Dried tetrahydrofurylpropane (DTHFP) containing 3 kg of cyclohexane, 500 g of butadiene monomer and 1.6 mmol in a 8 liter pressure-resistant reactor equipped with a dried, nitrogen-substituted temperature-adjusting jacket. And inject 5 mmol
After adding n-butyl lithium (BuLi) of 0.4
5 mmol of hexamethyleneimine (HMI) was quickly added, and polymerization was carried out at a starting temperature of 40 ° C. for 1 hour. The polymerization was performed under elevated temperature conditions, and the jacket temperature was adjusted so that the final temperature did not exceed 75 ° C. The polymerization system was uniformly transparent from the start to the end of the polymerization without any precipitation. The polymerization conversion was almost 100%. This polymerization system was further added with 1- {3- (triethoxysilyl) propyl}-
After adding 4.5 mmol of 4,5-dihydroimidazole (TEOSDI; 1 M cyclohexane solution), a denaturation reaction was performed for 30 minutes. Thereafter, 2,6-di-t- is added to the polymerization system.
The reaction was stopped by adding 0.5 ml of a 5% solution of butyl-p-cresol (BHT) in isopropanol,
The polymer was dried according to a conventional method to obtain a polymer I. The obtained polymer I was measured for microstructure (vinyl bond amount), molecular weight (Mw) and molecular weight distribution (Mw / Mn). Table 1 shows the results.

[0045]

[Table 1]

(Note) 1) Molecular weight Mw: Weight average molecular weight Mw / Mn: Molecular weight distribution 2) Terminal modifier TEOS: Tetraethoxysilane TEOSDI: 1- {3- (Triethoxysilyl) propyl} -4,5-dihydro Imidazole

Embedded image S340: N- (1,3-dimethylbutylidene) -3-
(Triethoxysilyl) -1-propanamine

Embedded image DMAPTE: dimethylaminopropyltriethoxysilane

Embedded image GPEOS: 3-glycidoxypropyltriethoxysilane

Embedded image 3) Modification initiator LHMI: reaction product of n-butyllithium and hexamethyleneimine

Examples 1 to 10 and Comparative Examples 1 and 2 (A) A rubber component comprising the types and amounts shown in Table 2, and (B)
Component, (C) silica as a reinforcing inorganic filler, and carbon black as another compounding agent, a silane coupling agent, a softener, zinc white, stearic acid, an antioxidant,
A rubber composition was prepared by compounding a compounding agent such as a vulcanization accelerator and sulfur. A radial tire for passenger cars of size 245 / 45R17 was manufactured according to a conventional method using the rubber composition as a side wall reinforcing layer. The maximum thickness of the sidewall portion reinforcing layer is shown in Table 2 as a reinforcing rubber gauge. The obtained tires were evaluated for ride comfort, run flat durability, and rolling resistance. The results are shown in Table 2.

[0048]

[Table 2]

[0049]

[Table 3]

(Note) * 1) Butadiene rubber: "BR01" [cis-1,4-polybutadiene, manufactured by JSR Co., Ltd., vinyl bond content 2.5%] * 2) Compound of general formula (I) Compound A of the formula (I): 1,6-bis (N, N'-dibenzylthiocarbamoyldithio) hexane (VULC
UREN TRIAL PRODUCT KA9188
BAYER) Compound B of general formula (I): 1,6-bis (N, N'-dimethylthiocarbamoyldithio) hexane (prototype synthetic product) Compound C of general formula (I): 1,6-bis ( N, N'-diethylthiocarbamoyldithio) hexane (prototype synthesis product) Compound D of general formula (I): 1,6-bis (N, N'-di (2-ethylhexyl) thiocarbamoyldithio) hexane (prototype synthesis) Product) Compound E of general formula (I): 1,6-bis (benzothiazolyldithio) hexane (prototype synthetic product) * 3) Citraconimide compound Citraconimide compound A: PERKALINK 90
0 (trademark, manufactured by FLEXSYS) Citraconimide compound B: N, N'-m-phenylene-biscitraconimide (prototype synthetic product) * 4) Acrylates Acrylates A: KAYARAD D-310 (trademark, Nippon Kayaku ( Acrylates B: KAYARAD DPHA [trademark,
Acrylates C: KAYARAD D-330 (trademark, manufactured by Nippon Kayaku Co., Ltd.) * 5) Silica: "Nipsil AQ" (trademark, manufactured by Nippon Silica Industry Co., Ltd.) * 6) Carbon black: "GPF" [trademark, #NP
G, manufactured by Asahi Carbon Co., Ltd.) * 7) Silane coupling agent: "Si69" (trademark, manufactured by Degussa AG) * 8) Softener: "Diana Process Oil NP-2"
4 "[trademark, manufactured by Idemitsu Kosan Co., Ltd.] * 9) Zinc flower: Zinc flower No. 3 [trademark, Mitsui Kinzoku Mining Co., Ltd.]
* 10) Stearic acid: "LUNAC RC beads"
[Trademark, manufactured by Kao Corporation] * 11) Antioxidant: "Nocrack 6C" [trademark, manufactured by Ouchi Shinko Chemical Industry Co., Ltd., N-phenyl-N '-(1,3
-Dimethylbutyl) -p-phenylenediamine] * 12) Vulcanization accelerator: "Noxera-NS" (trademark, manufactured by Ouchi Shinko Chemical Co., Ltd., N-tert-butyl-2-benzothiazolylsulfenamide) * 13) Sulfur “MUCRON-OT” [trademark, manufactured by Shikoku Chemicals Co., Ltd.]

From the above results, it can be seen that the pneumatic tire using the rubber composition having the specific properties according to the present invention for the side wall reinforcing layer has excellent ride comfort by significantly reducing the side reinforcing rubber gauge. It can be seen that since the rolling resistance was reduced and the decrease in the elastic modulus at a high temperature was suppressed, the run flat durability was excellent.

[0052]

According to the present invention, a rubber composition containing a conjugated diene-based polymer having a specific property is used for a tire side wall reinforcing rubber and / or a tire bead filler rubber. The pneumatic tire has excellent ride comfort, run-flat durability and rolling resistance, and is particularly excellent in durability in run-flat running, and can significantly extend the running distance.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of an example of a pneumatic tire of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pneumatic tire of the present invention 2 Carcass layer 2a Folded carcass ply 2b Down carcass ply 3 Belt layer 4 Bead core 5 Bead filler 6 Side wall part 7 Rubber reinforcing layer 8 Tread part

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C08K 5/103 C08K 5/103 5/3415 5/3415 5/40 5/40 7/22 7/22 C08L 9/00 C08L 9/00 15/00 15/00 F term (reference) 4J002 AC012 AC021 AC031 AC052 AC062 AC072 AC081 AC082 AC092 AC111 BB182 DE147 DE237 DJ017 DJ037 DM007 EH076 EU026 EV046 EV136 EV166 FA097 FD017 FD156 GN01 4J100 BA77H HA3561 JA29

Claims (22)

[Claims] 1. A rubber composition comprising a pair of left and right bead cores and a bead filler disposed radially outside of the bead core in a tire radial direction, wherein the rubber composition constituting the bead filler is (A) a conjugated diene unit. A vinyl bond amount of 25% or more and a weight average molecular weight (Mw) of 200,000 to 90
Weight average molecular weight and number average molecular weight (Mn)
And a rubber component containing 50% by weight or more of a conjugated diene-based polymer having a molecular weight distribution (Mw / Mn) of 1 to 4 represented by the following formula: (B) R ¹ -SS- A—S—S—R ² (I) wherein A is an alkylene group having 2 to 10 carbon atoms, R ¹ and R
² independently represents a monovalent organic group containing a nitrogen atom. ), At least one compound selected from citraconic imide compounds and acrylate compounds, and (C) a reinforcing inorganic filler. 2. A carcass layer, a tread portion disposed radially outside the carcass layer in a tire radial direction, a pair of sidewall portions disposed on the left and right sides of the tread portion, and a plurality of sidewall portions disposed on the sidewall portion. A rubber composition comprising a rubber reinforcing layer and the rubber reinforcing layer disposed on the side wall portion comprises: (A) a conjugated diene unit having a vinyl bond content of 25% or more and a weight average molecular weight (Mw) )
Is 200,000 to 900,000, and the molecular weight distribution (Mw / M) represented by the ratio of the weight average molecular weight to the number average molecular weight (Mn).
(B) a rubber component containing 50% by weight or more of a conjugated diene-based polymer having 1 to 4 and (B) a general formula (I) R ¹ -SSSASR ^2. I) wherein A is an alkylene group having 2 to 10 carbon atoms, R ¹ and R
² independently represents a monovalent organic group containing a nitrogen atom. ), At least one compound selected from citraconic imide compounds and acrylate compounds, and (C) a reinforcing inorganic filler. 3. A pair of left and right bead cores, a bead filler and a carcass layer disposed radially outward of the bead core in a tire radial direction, a tread portion disposed radially outward of the carcass layer in a tire radial direction, and a tread portion. A rubber composition comprising a pair of sidewall portions disposed on the left and right sides and a rubber reinforcing layer disposed on the sidewall portions, and a rubber composition constituting the bead filler and a rubber disposed on the sidewall portions. The rubber composition constituting the reinforcing layer has (A) a conjugated diene unit having a vinyl bond amount of 25% or more, a weight average molecular weight (Mw) of 200,000 to 900,000, and a weight average molecular weight and a number average molecular weight (Mn). the molecular weight distribution represented by the ratio of) (Mw / Mn) and the rubber component a conjugated diene polymer containing 50 wt% or more is that 1 to 4, (B) the general formula (I) R ¹ -S-S ^{A-S-S-R 2} ··· (I) ( wherein A represents an alkylene group having 2 to 10 carbon atoms, R ¹ and R
² independently represents a monovalent organic group containing a nitrogen atom. ), At least one compound selected from citraconic imide compounds and acrylate compounds, and (C) a reinforcing inorganic filler. 4. The molecular weight distribution (Mw / Mn) represented by the ratio of the weight average molecular weight Mw to the number average molecular weight Mn of the conjugated diene polymer is 1 to 3. 3. The pneumatic tire according to any one of 3. 5. The pneumatic tire according to claim 1, wherein the conjugated diene polymer is polybutadiene. 6. The method according to claim 1, wherein the polybutadiene comprises 60% by weight of the rubber component.
The pneumatic tire according to claim 5, wherein the pneumatic tire is contained in an amount of at least% by weight. 7. The rubber component (A) has a vinyl bond content of 25% or more in a conjugated diene unit, a weight average molecular weight (Mw) of 200,000 to 900,000, and a weight average molecular weight and a number average molecular weight (Mn). Molecular weight distribution (M
The pneumatic tire according to any one of claims 1 to 6, wherein (w / Mn) is 1 to 4 and a conjugated diene-based polymer containing a silicon atom in a molecule is contained. 8. The method according to claim 1, wherein the content of the conjugated diene-based polymer containing a silicon atom in the molecule is 50% by weight or more of the total amount of the conjugated diene-based polymer. The pneumatic tire as described. 9. The pneumatic tire according to claim 1, wherein the conjugated diene-based polymer component has a branched structure. 10. The rubber component (A), wherein the conjugated diene polymer containing a silicon atom in the molecule is obtained by introducing a silicon atom with a terminal modifier of alkoxysilane and / or aminoalkoxysilane. The pneumatic tire according to any one of claims 1 to 9, wherein 11. The terminal modifying agent may be methylethoxysilane, tetraethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 1- {3- (triethoxysilyl) propyl ｝ -4,5-dihydroimidazole, N- (1,
3-dimethylbutylidene) -3- (triethoxysilyl)
The pneumatic tire according to claim 10, wherein the pneumatic tire is at least one selected from -1-propanamine and dimethylaminopropyltriethoxysilane. 12. A in the general formula (I) of the component (B) is:
The pneumatic tire according to any one of claims 1 to 11, wherein the pneumatic tire is a hexamethylene group. 13. The pneumatic tire according to claim 1, wherein the citraconic imide compound as the component (B) is a biscitraconic imide. 14. The acrylate component (B) is a polyhydric ester of a polyhydric alcohol and acrylic acid, or a polyhydric ester of a polyhydric alcohol and acrylic acid or another carboxylic acid. The pneumatic tire according to any one of claims 1 to 13. 15. The compound represented by the general formula (I) as the component (B) is 1,6-bis (N, N′-dibenzylthiocarbamoyldithio) hexane. 15. The pneumatic tire according to any one of items 14 to 14. 16. The pneumatic tire according to claim 13, wherein the biscitraconimide of the component (B) is 1,6-bis (citraconimidomethyl) benzene. 17. The pneumatic tire according to claim 1, wherein the acrylate as the component (B) is an acyl group-modified dipentaerythritol acrylate. 18. (A) For 100 parts by weight of the rubber component,
The pneumatic tire according to any one of claims 1 to 17, wherein the component (B) is added in an amount of 0.5 to 20 parts by weight. 19. The pneumatic tire according to claim 1, wherein (C) the reinforcing inorganic filler is porous. 20. (C) The reinforcing inorganic filler has the following general formula: mM ¹ .xSiO _y .zH ₂ O (where M ¹ is at least one selected from Al, Mg, Ti and Ca) M is 1 to 5, x is 0 to 10, and y is 2 to
5, z is an integer of 0 to 10. The pneumatic tire according to any one of claims 1 to 19, comprising a compound represented by the formula: 21. (C) The reinforcing inorganic filler is silica,
The pneumatic tire according to any one of claims 1 to 20, wherein the pneumatic tire is at least one selected from aluminum hydroxide, aluminum oxide, calcium carbonate, magnesium carbonate, clay, and zeolite. 22. The pneumatic tire according to claim 1, wherein the BET type nitrogen adsorption specific surface area of the reinforcing inorganic filler (C) is 50 to 400 m ² / g.