JP2001348458A - Rubber composition and pneumatic tire obtained using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition improved in heat resistance and suitable as a reinforcing rubber for a sidewall portion for a tire and as a bead filler rubber for a tire, and a pneumatic tire obtained using the same. SOLUTION: The heat resistant rubber comprises (A) a rubber component comprising at least one selected among natural rubbers and diene-based synthetic rubbers and (B) 1,3-bis(citraconimide)benzene. The pneumatic tire is obtained by using the rubber composition as the rubber-reinforcing layer of the sidewall portion and/or as a bead filler.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rubber composition and a pneumatic tire using the same. For more information,
The present invention provides a rubber composition having improved heat resistance, which is particularly suitable as a sidewall reinforcing rubber for tires or a bead filler rubber for tires, and air obtained by using this rubber composition for a sidewall reinforcing layer or a bead filler. It is related to a tire with a tire.

[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 conventional rubber compositions used for these, in particular, as in so-called run-flat running, the vehicle travels in a state where the internal pressure of the tire (hereinafter, referred to as internal pressure) is reduced due to puncture of the tire. In addition, when the temperature is 200 ° C. or higher, a crosslinked portion formed by vulcanization or the like, or a polymer itself constituting a rubber component, tends to be cut. Due to this, since the elastic modulus decreases, the deflection of the tire increases, heat generation proceeds, and the breaking limit of rubber decreases, as a result,
Tires have a problem that they break down relatively early.
As one of means for delaying the occurrence of such a failure as much as possible, by changing the compounding, the elastic modulus of the rubber composition to be used is increased as much as possible, or its loss tangent (tan δ) is set as small as possible. Although a method of suppressing heat generation of the rubber composition itself is known, there is a limit in an approach from a compounding side, and in run-flat running, a side reinforcing layer and a bead filler are required to secure a certain durable distance. As a result, during normal driving, undesired situations such as deterioration of ride comfort, deterioration of noise level, and increase in weight are caused.

[0003]

SUMMARY OF THE INVENTION The present invention relates to a rubber composition having improved heat resistance which is suitable as a reinforcing rubber for a sidewall portion of a tire or a bead filler rubber for a tire under such a circumstance. It is an object of the present invention to provide a pneumatic tire using the composition, particularly having excellent durability in run flat running.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, a rubber composition containing a specific compound has excellent heat resistance and has a side wall reinforcing rubber for tires. And a bead filler rubber for tires, and found that a pneumatic tire using this rubber composition for a sidewall reinforcing layer or a bead filler has excellent durability especially in run-flat running. Was. The present invention has been completed based on such findings. That is, the present invention provides a heat-resistant rubber composition comprising (A) a rubber component comprising at least one of natural rubber and a diene-based synthetic rubber, and (B) 1,3-bis (citraconimide) benzene. Is provided. Further, the present invention further comprises, as the component (B) of the composition, together with the above 1,3-bis (citraconimido) benzene, further comprising a compound represented by the general formula (I) R ¹ -SSSASR ² ... (I) (wherein, A represents an alkylene group having 2 to 10 carbon atoms, and R ¹ and R ² each independently represent a monovalent organic group containing a nitrogen atom.) And / or a rubber composition containing an acrylate compound.

Further, the present invention provides a ply comprising a pair of left and right ring-shaped bead cores, a bead filler disposed radially outside the bead core in a tire radial direction, and a plurality of cords arranged in parallel in a covering rubber. A carcass layer composed of at least one sheet, a belt layer disposed radially outward of the carcass layer, a tread portion disposed radially outward of the belt layer, and left and right sides of the tread portion. In a pneumatic tire comprising a pair of sidewall portions and a rubber reinforcing layer disposed on the sidewall portion, the pneumatic tire includes a rubber reinforcing layer disposed on the sidewall portion and / or the bead filler. The present invention also provides a pneumatic tire using the rubber composition.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the rubber composition of the present invention,
As the component (A), a natural rubber and / or a diene-based synthetic rubber is used. Here, as the diene-based synthetic rubber,
For example, polyisoprene synthetic rubber (IR), polybutadiene rubber (BR), styrene-butadiene rubber (SB
R), acrylonitrile butadiene rubber (NBR), chloroprene rubber (CR), butyl rubber (IIR) and the like. The natural rubber and the diene-based synthetic rubber of the component (A) may be used alone or in combination of two or more. Further, a reinforcing filler can be used in the rubber composition of the present invention. The type of the reinforcing filler is not particularly limited, and those usually used in the rubber industry can be appropriately selected. Preferably, carbon black, silica, aluminum hydroxide and the like are used, and silica and aluminum hydroxide are used. In such a case, by using the coupling agent together with the coupling agent, the reinforcing property with the rubber can be further enhanced. In the rubber composition of the present invention, in order to improve heat resistance, as a heat aging inhibitor of the component (B),

[0007]

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1,3-bis (citraconimide) benzene (also known as N, N'-m-phenylene-biscitraconimide) is used. This 1,3-bis (citraconimido) benzene exhibits an effect of improving the heat resistance of the rubber composition, but its action reacts with the conjugated CＣC in the main chain generated at the time of crosslinking cleavage at a high temperature. , C-
This is considered to be due to the early generation of C crosslinking. In the present invention, as the component (B),
Along with 1,3-bis (citraconimido) benzene, a compound represented by the general formula (I) R ¹ -SSSASR ² (I) wherein A represents 2 to 10 carbon atoms And R ¹ and R ² each independently represent a monovalent organic group containing a nitrogen atom.) And / or an acrylate compound.

In the above 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)

[0010]

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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 viewpoint 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 them, 1,6-bis (N, N′-dibenzylthiocarbamoyldithio) hexane is particularly preferable from the viewpoint of the effect.

The compound represented by the general formula (I) has 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.

Further, as the acrylate as the component (B), a polyhydric ester of a polyhydric alcohol and acrylic acid or acrylic acid and another carboxylic acid is preferable from the viewpoint of the effect. Is, for example, the general formula (II)

[0016]

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Compounds represented by the following formulas can be preferably mentioned. In the general formula (II), 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. Among the compounds represented by the general formula (II), p is an integer of 3 to 6 and q is 0 to
An integer of 3 and p + q = 3 to 6 are preferable from the viewpoint of the effect.

The general formula (III) A- (OH) _{p + q} (III) used for forming the acrylates represented by the general formula (II) (where A and p, q are as defined above) The same applies to the polyhydric alcohol represented by the formula (3), preferably a tri- to hexa-hydric alcohol, such as glycerin,
Trimethylolethane, trimethylolpropane, diglycerin, pentaerythritol, dipentaerythritol, sorbitol and the like. The general formula (II)
From the viewpoint of the effect, polyhydric esters of dipentaerythritol having 3 to 6 acryloyl groups in one molecule and acrylic acid, and acyl having 3 to 5 acryloyl groups in one molecule are preferable from the viewpoint of the effect. Group-modified dipentaerythritol acrylate is preferred. Such compounds are commercially available as shown below. For example, the expression

[0019]

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(Compounds with a = 5, b = 1 and a = 6, b =
0) is a compound represented by “KAY
ARAD DPHA "(trademark, manufactured by Nippon Kayaku Co., Ltd.)

[0021]

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(R ¹ is Alkynoyl
l) represents a group. ) Is c = 5, d = 1
In the case of KAYAARD D-310 (trademark, manufactured by Nippon Kayaku Co., Ltd.), and in the case of c = 3, d = 3,
RAD D-330 "(trademark, manufactured by Nippon Kayaku Co., Ltd.). The acrylate of the component (B) exhibits the effect of improving the heat resistance of the rubber composition, but its action reacts with the conjugate C = C in the main chain generated at the time of crosslinking cleavage at a high temperature, This is considered to be due to the effective formation of C crosslinks.

The amount of the component (B) is preferably in the range of 0.5 to 20 parts by weight based on 100 parts by weight of the rubber component (A). If this amount is 0.
If it is less than 5 parts by weight, the effect of preventing heat aging cannot be sufficiently obtained,
The desired effect of improving heat resistance may not be exhibited. On the other hand, if it exceeds 20 parts by weight, the effect is not so much improved in spite of its amount, which is rather economically disadvantageous and causes other physical properties of the obtained rubber composition to deteriorate. In consideration of the heat aging prevention effect, other physical properties and economics of the rubber composition, the more preferable compounding amount of the component (B) is
It is in the range of 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 above-mentioned component (B). Other examples of the heat aging inhibitor include sodium 1,6-hexamethylenedithiosulfate dihydrate and a compound 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, but is preferably acrylate or methacrylate, particularly preferably a polyvalent ester of a polyhydric alcohol and 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, substituted methylols, pentaerythritols, and alkylene oxide adducts of polyhydric alcohols. And polyesters or oligoesters having two or more alcoholic hydroxyl groups. Among them, particularly preferred are a methylol-substituted alkylene glycol and a polymer 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. Among them, particularly preferred are dipentaerythritol pentamethacrylate; dipentaerythritol trimethacrylate, and trimethylol. It is 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. In the rubber composition of the present invention, in addition to the above-described components, sulfur generally used in the rubber industry, a vulcanizing agent such as a peroxide, a vulcanization accelerator,
Various compounding agents such as anti-aging agent, softener, inorganic filler,
It can be appropriately contained. Further, the rubber composition of the present invention may be a composite with particles, fibers, cloths and the like of various materials.

The rubber composition of the present invention has excellent heat resistance and is particularly suitable as a tire side wall reinforcing rubber (side reinforcing rubber) or a tire bead filler rubber. The heat resistance of the rubber composition of the present invention can be evaluated as described below. That is, the dynamic storage elastic modulus of a sample of the vulcanized rubber composition is measured under elevated temperature conditions, and the change in the dynamic storage elastic modulus with respect to temperature is represented by a graph. From this graph, the value of the peak dynamic storage modulus and its temperature,
The value of the dynamic storage modulus of the bottom and its temperature, further 25
The dynamic storage modulus at 0 ° C. is determined. Then, the bottom dynamic storage modulus / peak dynamic storage modulus is calculated from the above values. The larger the value, the larger the value of the dynamic storage modulus at 250 ° C., the better the heat resistance.

Next, regarding the pneumatic tire of the present invention,
This will be described with reference to the accompanying drawings. FIG. 1 is a partial cross-sectional view of an example of a pneumatic tire according to the present invention. A bead filler 5 and a carcass layer 2 composed of at least one ply in which a plurality of parallel cords are embedded in a covering rubber.
A belt layer 3 disposed radially outward of the carcass layer 2 in the tire radial direction; a tread portion 8 disposed radially outward of the belt layer 3 in the tire radial direction; And a rubber reinforcing layer 7 provided on the side wall portion 6. The carcass layer 2 has a folded carcass ply 2a and a down carcass ply 2b, and both ends of the folded carcass ply 2a are folded around the bead core 4 to form folded ends. The bead filler 5 is located between the folded carcass ply 2a and its folded end, and the down carcass ply 2b is arranged between the sidewall portion 6 and the folded end of the folded carcass ply 2a. ing. The rubber reinforcing layer 7 is arranged in a crescent cross section on the inner peripheral surface of the sidewall portion of the folded carcass ply 2a.

In the pneumatic tire of the present invention, the above-described bead filler 5 and / or the rubber reinforcing layer 7 are formed using the above-described rubber composition of the present invention. Since the rubber composition of the present invention can maintain the elastic modulus as designed at low temperatures, the ride comfort and noise level are substantially deteriorated due to the increase in the elastic modulus during normal running. Absent. On the other hand, the temperature of the rubber composition was 170 ° C. due to large deformation due to puncture of the tire.
Even in the case described above, since a decrease in the elastic modulus is suppressed, heat generation at a high temperature is suppressed, and the durability of the tire can be improved. Therefore, the pneumatic tire of the present invention in which this rubber composition is used for the rubber reinforcing layer and the bead core of the sidewall portion has a significantly improved durability, particularly in run-flat running, and can significantly extend the running distance. .

[0030]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The properties of the obtained rubber composition and the run flat durability of the tire were determined according to the following methods. (1) Characteristics such as dynamic storage 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%, and the frequency was 52 Hz. At a temperature, the dynamic storage modulus is measured at a rate of temperature rise of 3 ° C./min, and a change in the dynamic storage modulus with respect to the temperature is represented by a graph. From this graph,
The value of the peak dynamic storage modulus and its temperature, the value of the bottom dynamic storage modulus and its temperature, and the dynamic storage modulus at 250 ° C. were determined, and from the above values, the bottom dynamic storage modulus / The peak dynamic storage modulus was calculated. Each of the above values was indicated as an index with Comparative Example 1 being 100. The larger the index of the bottom dynamic storage modulus / the peak dynamic storage modulus and the larger the index of the dynamic storage modulus at 250 ° C., the better the heat resistance.

(2) Run-flat durability of tire Assemble the rim at normal pressure and seal the internal pressure of 200 kpa.
After being left at room temperature of 8 ° C. for 24 hours, the core of the valve was removed, the internal pressure was set to atmospheric pressure, and a drum running test was performed under the conditions of a load of 5.6 kN (570 kg), a speed of 89 km / h, and a room temperature of 38 ° C. The running distance until the occurrence of a failure at this time was defined as run flat durability, and was represented by an index with Comparative Example 1 being 100. The larger the index, the better the run flat durability.

Examples 1 to 17 50.0 parts by weight of natural rubber and butadiene rubber "BR0"
1 "[trademark, manufactured by JSR Corporation] 100 parts by weight of a rubber component consisting of 50.0 parts by weight, carbon black FEF 60.0 parts by weight, spindle oil 3.0 parts by weight, zinc white 5.0 parts by weight 1.0 parts by weight of stearic acid, anti-aging agent "Nocrack 6C" [trademark, N-phenyl-N '-(1,3-dimethylbutyl) -p-phenylenediamine, manufactured by Ouchi Shinko Chemical Industry Co., Ltd.] 2.0 parts by weight, 3.5 parts by weight of a vulcanization accelerator "NOCSELA-NS" (trademark, N-tert-butyl-2-benzothiazolylsulfenamide, manufactured by Ouchi Shinko Chemical Co., Ltd.), sulfur 5.0
Parts by weight and 1,3 of the amount shown in Table 1 as the component (B)
-A rubber composition was prepared by blending bis (citraconimide) benzene (prototype synthetic product). Table 1 shows the properties of the vulcanizate. Next, a radial tire for passenger cars having a size of 225 / 60R16 was manufactured according to a conventional method using the rubber composition for the side wall portion reinforcing layer and / or the bead filler, and the run flat durability was evaluated. The results are shown in Table 1.

Comparative Example 1 A rubber composition was prepared in the same manner as in Example 1, except that the component (B) was not used. Table 1 shows the properties of the vulcanizate. Next, the tire was manufactured in the same manner as in Example 1 by using the above composition for both the sidewall part reinforcing layer and the bead filler, and the run flat durability was evaluated. The results are shown in Table 1.

Examples 18 and 19 30.0 parts by weight of natural rubber and butadiene rubber "BR0"
1 "[trademark, manufactured by JSR Corporation] 60.0 parts by weight of carbon black FEF, 3.0 parts by weight of spindle oil, 5.0 parts by weight of zinc white per 100 parts by weight of a rubber component consisting of 70.0 parts by weight. 1.0 parts by weight of stearic acid, antioxidant "Nocrack 6C" [trademark, N-phenyl-N '-(1,3-dimethylbutyl) -p-phenylenediamine, manufactured by Ouchi Shinko Chemical Co., Ltd.] 2 5.0 parts by weight, 2.5 parts by weight of a vulcanization accelerator "Noxera-NS" (trademark, N-tert-butyl-2-benzothiazolylsulfenamide, manufactured by Ouchi Shinko Chemical Co., Ltd.), and sulfur 5. A rubber composition was prepared by mixing 0 parts by weight and the type and amount of the component compound (B) shown in Table 1 (see footnote in the table). Table 1 shows the properties of the vulcanizate. In addition, acrylates A and B are silica (Nipsil AQ,
(Manufactured by Nippon Silica Industry Co., Ltd.) as a 50% by weight carrier. Next, a tire was manufactured in the same manner as in Example 1 by using the rubber composition for both the sidewall portion reinforcing layer and the bead filler, and its run flat durability was evaluated. The results are shown in Table 1.

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

[Table 3]

(Note) 1) Compound A of general formula (I): 1,6-bis (N, N ')
-Dibenzylthiocarbamoyldithio) hexane ("VULCUEN TRIAL PRODUU" manufactured by Bayer AG)
CT KA 9188 "

[0039]

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2) Compound B of the formula (I): 1,6-bis (N, N'-dimethylthiocarbamoyldithio) hexane (prototype synthetic product)

[0041]

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3) Acrylates A: "KAYARAD"
D310 "[trademark; manufactured by Nippon Kayaku Co., Ltd.] 4) Acrylates B:" KAYARAD DPHA "
[Trademark; manufactured by Nippon Kayaku Co., Ltd.] 5) Applicable members: The rubber compositions shown in Table 1 are applied.

As is clear from Table 1, the rubber composition containing 1,3-bis (citraconimide) benzene as the component (B) has an effect of improving heat resistance. 0.5 to 10 with respect to 100 parts by weight of the component
It can be seen that the rubber composition blended in parts by weight has a large effect of improving heat resistance. And, this rubber composition,
The pneumatic tire used for the bead filler or the side wall reinforcing layer has good run flat durability, and particularly, the tire used for both the side wall reinforcing layer and the bead filler has excellent run flat durability. It can be seen that it has.

[0044]

According to the present invention, by using a specific compound, a rubber composition having improved heat resistance can be obtained. This is particularly useful for a tire side wall reinforcing rubber and a tire bead filler. Suitable as rubber.
The pneumatic tire of the present invention using this rubber composition for the side wall portion reinforcing layer and the bead filler has excellent durability especially 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 according to 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 symbol FI Theme coat ゛ (Reference) C08K 5/103 C08K 5/103 5/3415 5/3415 5/36 5/36 5/40 5/40 C08L 9/00 C08L 9/00

Claims (16)

[Claims] 1. A heat-resistant rubber composition comprising (A) a rubber component comprising at least one of natural rubber and diene-based synthetic rubber, and (B) 1,3-bis (citraconimide) benzene. 2. The component (B) further includes a compound represented by the following general formula (I): R ¹ -SSSASR ² (I) wherein A has 2 to 10 carbon atoms. The alkylene group, R ¹ and R ² each independently represent a monovalent organic group containing a nitrogen atom.) And / or an acrylate compound. Composition. 3. The rubber composition according to claim 2, wherein A in the compound (B) represented by the general formula (I) is a hexamethylene group. 4. The compound (B) wherein R ¹ and R ² in the compound represented by the general formula (I) are each a monovalent organic group containing at least one aromatic ring and containing a nitrogen atom. Item 4. The rubber composition according to item 2 or 3. 5. R ¹ and R ² in the compound represented by the general formula (I) as the component (B) are each represented by = NC (= S)-in which a carbon atom is bonded to a dithio group. The rubber composition according to any one of claims 2 to 4, which is a monovalent organic group containing a bonding group. 6. The compound represented by the general formula (I) as the component (B) is a compound represented by the general formula (Ia): (Wherein, R ^{3 to} R ⁶ each independently represent an alkyl group,
An aryl group or an aralkyl group, wherein at least one of R ³ and R ⁴ and at least one of R ⁵ and R ⁶ are an aryl group having 6 to 20 carbon atoms or an aralkyl group having 7 to 20 carbon atoms, and n is Shows an integer of 2 to 10. The rubber composition according to claim 5, which is an α, ω-bis (N, N'-dihydrocarbylthiocarbamoyldithio) alkane represented by the formula: 7. The rubber composition according to claim 6, wherein the compound represented by the general formula (I) as the component (B) is 1,6-bis (N, N′-dibenzylthiocarbamoyldithio) hexane. . 8. The rubber composition according to claim 2, wherein the acrylate component (B) is a polyhydric ester of a polyhydric alcohol and acrylic acid or acrylic acid and another carboxylic acid. 9. The acrylate of the component (B) has the general formula
(II) (In the formula, A is a residue excluding a hydroxyl group of a (p + q) -valent polyhydric alcohol, R is a hydrogen atom or an acyl group other than an acryloyl group, p is an integer of 2 to 10, and q is an integer of 0 to 8. The compound represented by the formula: p + q = 2 to 10.). 10. The acrylate represented by the general formula (II) as the component (B), wherein p is an integer of 3 to 6 and q is 0 to 10.
The rubber composition according to claim 9, which is an integer of 3 and p + q = 3 to 6. 11. The acrylate represented by the general formula (II) as the component (B) is a polyvalent ester of dipentaerythritol having 3 to 6 acryloyl groups in one molecule and acrylic acid. 11. The rubber composition according to item 10. 12. The rubber composition according to claim 11, wherein the acrylate represented by the general formula (II) of the component (B) is an acyl group-modified dipentaerythritol acrylate having 3 to 5 acryloyl groups in one molecule. object. 13. Per 100 parts by weight of component (A),
The rubber composition according to any one of claims 1 to 12, further comprising 0.5 to 10 parts by weight of the component (B). 14. The rubber composition according to claim 1, which is used as a bead filler rubber for a tire. 15. The rubber composition according to claim 1, which is used as a sidewall reinforcing rubber for a tire. 16. A pair of left and right ring-shaped bead cores,
A bead filler disposed outside the bead core in the tire radial direction, a carcass layer including at least one ply in which a plurality of cords arranged in parallel are embedded in the covering rubber, and The disposed belt layer, a tread portion disposed outside the belt layer in the tire radial direction, a pair of sidewall portions disposed on the left and right sides of the tread portion, and a rubber disposed on the sidewall portion. A pneumatic tire comprising a reinforcing layer, wherein the rubber composition according to any one of claims 1 to 13 is used for the rubber reinforcing layer and / or the bead filler disposed on the sidewall portion. And pneumatic tires.