JP2010070745A - Rubber composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition which uses a vulcanization accelerator having a vulcanization-retarding effect equal to or larger than that of DCBS without using such a vulcanization retarder as CTP having possibility causing problems such as the deterioration of rubber physical properties and blooming after vulcanized, prevents the deterioration of rubber burst resistance, has good workability, can minimize the scorch of rubber, and is excellent in thermal ageing resistance. <P>SOLUTION: There is provided the rubber composition characterized by comprising a rubber component, a sulfenamide-based vulcanization accelerator represented by formula (I) [wherein, R<SP>1</SP>is 3-12C branched alkyl; R<SP>2</SP>is 1-10C straight chain alkyl or 3-10C branched alkyl; R<SP>3</SP>to R<SP>6</SP>are each identically or differently H, 1-4C straight chain alkyl or alkoxy, or 3-4C branched alkyl or alkoxy; (n) is 0 or 1; (x) is 1 or 2], sodium 1, 6-hexamethylene-dithiosulfate dihydrate represented by formula (II), and sulfur. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rubber composition containing a specific sulfenamide-based vulcanization accelerator, and more particularly to a rubber composition that can be suitably used for rubber articles such as tires and conveyor belts using steel cord as a reinforcing material. .

  Conventionally, it is desired that rubber products such as automobile tires, conveyor belts, hoses and the like have not only strength but also various high characteristics. In particular, rubber articles such as tires and conveyor belts using steel cord as a reinforcing material are required to have excellent adhesiveness and heat aging resistance.

  For example, Patent Document 1 includes 1,6-hexamethylene-sodium dithiosulfate dihydrate (hereinafter also referred to as “HTS”) without blending the organic acid cobalt salt or the like used as an adhesion promoter. ) Containing a rubber composition is disclosed. Thereby, this composition can aim at the improvement of heat aging resistance, avoiding the enlargement and cohesive failure of the adhesion interface layer resulting from cobalt.

  On the other hand, a composite material in which a metal reinforcing material such as a steel cord is coated with a rubber composition to reinforce the rubber and improve the strength and durability is often used. In the case of bonding such rubber and metal, a method of simultaneously bonding rubber and metal, that is, a direct vulcanization bonding method is known, but vulcanization of rubber and bonding of rubber and metal are performed simultaneously. In view of the above, it is considered useful to use a sulfenamide-based vulcanization accelerator that gives a slow effect to the vulcanization reaction. Among the commercially available sulfenamide-based vulcanization accelerators, examples of the vulcanization accelerator that gives the slowest effect to the vulcanization reaction include N, N′-dicyclohexyl-2-benzothiazolylsulfene. Amides (hereinafter abbreviated as “DCBS”) are known. Furthermore, when slow action is required, a sulfenamide vulcanization accelerator and a vulcanization retarder such as N- (cyclohexylthio) phthalimide (hereinafter abbreviated as “CTP”) are used in combination. Things are also done.

Japanese Patent Laid-Open No. 10-195237

  However, there is still room for improvement. For example, when HTS as described above is blended, when a conventional vulcanization accelerator is used in combination, the Mooney viscosity tends to increase more than necessary, and good kneading work tends not to be realized. It seems that it is difficult to secure. In addition, when a conventional vulcanization accelerator and a vulcanization retarder as described above are used in combination, depending on the amount of the vulcanization retarder, the physical properties of the vulcanized rubber may be adversely affected, and the vulcanization There arises a problem that the appearance of the rubber is deteriorated and blooming is adversely affected.

  Therefore, the present invention has a vulcanization delay effect equivalent to or better than that of DCBS without using a vulcanization retarder such as CTP which may cause problems such as deterioration of rubber physical properties after vulcanization and blooming. To provide a rubber composition that uses a vulcanization accelerator and has good workability while preventing a decrease in the fracture resistance of rubber, can reduce rubber burns as much as possible, and is excellent in heat aging resistance. With the goal.

  In order to solve the above-mentioned problems, the present inventor has adopted a specific sulfenamide vulcanization accelerator, while preventing a decrease in the fracture resistance of rubber, further improving workability and excellent heat aging resistance. The present inventors have found a rubber composition capable of imparting the above-mentioned properties and have completed the present invention.

  That is, the rubber composition of the present invention comprises a rubber component, a sulfenamide vulcanization accelerator represented by the formula (I), 1,6-hexamethylene-sodium dithiosulfate · 2 represented by the formula (II) It is characterized by containing a hydrate and sulfur.

(In formula (I), R ¹ represents a branched alkyl group having 3 to 12 carbon atoms, and R ² represents a linear alkyl group having 1 to 10 carbon atoms or a branched alkyl group having 3 to 10 carbon atoms. ^{3 to} R ⁶ are a hydrogen atom, a linear alkyl group or alkoxy group having 1 to 4 carbon atoms, or a branched alkyl group or alkoxy group having 3 to 4 carbon atoms, which may be the same as or different from each other. N represents 0 or 1, and x represents 1 or 2.)

It is desirable to contain the sulfenamide-based vulcanization accelerator in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass of the rubber component. It is desirable to contain 6-hexamethylene-sodium dithiosulfate dihydrate in an amount of 0.3 to 5 parts by mass.
Furthermore, it is desirable to contain the sulfur in an amount of 0.3 to 10 parts by mass with respect to 100 parts by mass of the rubber component.

In the formula (I), R ¹ and R ² are preferably branched alkyl groups having a branch at the α-position, R ¹ is preferably a tert-butyl group, and n is preferably 0. Further, R ¹ is a tert-butyl group, R ² is a linear alkyl group having 1 to 6 carbon atoms or a branched alkyl group having 3 to 6 carbon atoms, and R ^{3 to} R ⁶ are preferably hydrogen atoms. . R ¹ is a tert-butyl group, R ² is a linear alkyl group having 1 to 6 carbon atoms or a branched alkyl group having 3 to 6 carbon atoms, R ^{3 to} R ⁶ are hydrogen atoms, and n is preferably 0, R ¹ is a tert-butyl group, R ² is a methyl group, an ethyl group or an n-propyl group, R ^{3 to} R ⁶ are hydrogen atoms, and n is 0 It is preferable that R ¹ is a tert-butyl group, R ² is an ethyl group, R ^{3 to} R ⁶ are hydrogen atoms, and n is 0.

The rubber composition preferably further contains a cobalt-based component composed of cobalt alone and / or a compound containing cobalt, and the content of the cobalt-based component is 0 as the amount of cobalt with respect to 100 parts by mass of the rubber component. An amount of 0.03 to 3 parts by mass is desirable. The cobalt-containing compound may be a cobalt salt of an organic acid.
Further, the rubber component may contain at least one of natural rubber and polyisoprene rubber, and may contain natural rubber in an amount of 50% by mass or more in 100% by mass of the rubber component.

  According to the present invention, since a vulcanization accelerator having a vulcanization retarding effect equivalent to or better than that of DCBS is used, an increase in Mooney viscosity is effectively suppressed and the kneading operation is facilitated, and an appropriate Mooney scorch is provided. You can keep time. In addition, there is no need to use a vulcanization retarder such as CTP, which may cause problems such as deterioration of rubber physical properties and blooming after vulcanization, which may adversely affect the appearance and adhesion of vulcanized rubber. Absent. Therefore, it is possible to obtain a rubber composition having excellent heat aging resistance as well as reducing the occurrence of rubber burns as much as possible while effectively preventing the deterioration of the fracture resistance of the rubber while maintaining good workability.

  Therefore, the rubber composition of the present invention can be suitably used for rubber articles such as tires and conveyor belts using steel cord as a reinforcing material.

Hereinafter, the present invention will be specifically described.
The rubber composition of the present invention comprises a rubber component, a sulfenamide vulcanization accelerator represented by the formula (I), 1,6-hexamethylene-sodium dithiosulfate dihydrate represented by the formula (II) It is characterized by containing a product and sulfur.

  The rubber component used in the present invention is not particularly limited as long as it is a rubber used in rubber products such as tires and industrial belts, and sulfur crosslinking is possible if the rubber component has a double bond in the main chain. The sulfenamide vulcanization accelerator represented by the above formula (I) functions effectively. For example, natural rubber or synthetic rubber is used. Specific examples of the synthetic rubber include polyisoprene rubber, styrene-butadiene copolymer, polybutadiene rubber, ethylene-propylene-diene copolymer, chloroprene rubber, halogenated butyl rubber, and acrylonitrile-butadiene rubber.

  The rubber component preferably contains at least one of natural rubber and polyisoprene rubber from the viewpoint of adhesion to a metal reinforcing material such as a steel cord. Further, from the viewpoint of durability of industrial belt rubber, it is desirable that natural rubber is contained in an amount of 50% by mass or more in 100% by mass of the rubber component. There is no restriction | limiting in particular about an upper limit, 100 mass% may be sufficient. In this case, the remainder is a synthetic rubber, and it is desirable to include at least one of the above synthetic rubbers.

  The sulfenamide vulcanization accelerator represented by the above formula (I) used in the present invention is a vulcanization equivalent to DCBS which is a conventional sulfenamide vulcanization accelerator represented by the following formula (X). It has a delay effect, can effectively suppress an increase in Mooney viscosity, and can secure a suitable Mooney scorch time. Moreover, it is excellent in adhesion durability in direct vulcanization adhesion with a metal reinforcing material such as a steel cord, and can be suitably used for a rubber composition for coating a thick rubber product.

In the present invention, R ¹ in the sulfenamide vulcanization accelerator represented by the above formula (I) represents a branched alkyl group having 3 to 12 carbon atoms. When R ¹ is a branched alkyl group having 3 to 12 carbon atoms, the vulcanization acceleration performance of the sulfenamide vulcanization accelerator is good and the adhesion performance can be enhanced.

Specific examples of R ¹ include isopropyl, isobutyl, triisobutyl, sec-butyl, tert-butyl, isoamyl (isopentyl), neopentyl, and tert-amyl (tert-pentyl). , Isohexyl group, tert-hexyl group, isoheptyl group, tert-heptyl group, isooctyl group, tert-octyl group, isononyl group, tert-nonyl group, isodecyl group, tert-decyl group, isoundecyl group, tert-undecyl group, isododecyl Group, tert-dodecyl group and the like. Among these, a branched alkyl group having a branch at the α-position, that is, a tert-alkyl group having 3 to 12 carbon atoms is preferable from the viewpoint of obtaining a suitable Mooney scorch time, and in particular, a tert-butyl group, A tert-amyl group (tert-pentyl group), a tert-dodecyl group, and a triisobutyl group are preferable. Among them, a tert-butyl group is most preferable from the viewpoint of improving adhesion and vulcanizing speed equivalent to that of DCBS in a balanced manner. .

  N in the sulfenamide vulcanization accelerator represented by the above formula (I) represents 0 or 1, and is preferably 0 from the viewpoint of effects such as ease of synthesis and raw material cost. X in the formula (I) represents an integer of 1 or 2. When x is 3 or more, the reactivity becomes too high, so that the stability of the sulfenamide vulcanization accelerator is lowered and workability may be deteriorated.

These are presumed to be because the more Moony scorch time tends to be imparted as the bulky group exists in the vicinity of —N— adjacent to R ¹ . Therefore, for example, when R ¹ in the above formula (I) is a tert-butyl group and n is 0, R ¹ is a cyclohexyl group, and in the vicinity of —N— as compared with DCBS where n is 0 It is considered that the former is bulkier and can provide a more preferable Mooney scorch time. Furthermore, in combination with R ² described later, by appropriately controlling the bulk height of the substituent located in the vicinity of -N-, it balances a suitable vulcanization speed and good adhesiveness while taking into account human accumulation. It is possible to perform well.

In the present invention, R ² in the sulfenamide vulcanization accelerator represented by the above formula (I) represents a linear alkyl group having 1 to 10 carbon atoms or a branched alkyl group having 3 to 10 carbon atoms. When R ² is a straight chain having 1 to 10 carbon atoms or a branched alkyl group having 3 to 10 carbon atoms, the sulfenamide-based vulcanization accelerator has good vulcanization acceleration performance and also improves adhesion performance. be able to.

Specific examples of R ² include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl (1-methylpropyl), tert-butyl, n- Amyl group (n-pentyl group), sec-amyl group (1-methylbutyl group), isoamyl group (isopentyl group), neopentyl group, tert-amyl group (tert-pentyl group), 1-methylpentyl group, n-hexyl Group, isohexyl group, n-heptyl group, isoheptyl group, n-octyl group, iso-octyl group, nonyl group, isononyl group, decyl group, undecyl group, dodecyl group and the like. Among these, from the viewpoint of consideration of effects such as ease of synthesis and raw material costs and human body accumulation, when R ² is a linear alkyl group, it is preferably 1 to 4 carbon atoms, 3 is more preferable, and C 1-2 is most preferable. In addition, when R ² is a branched alkyl group, a branched alkyl group having a branch at the α-position, that is, a bond, from the viewpoint of exhibiting a suitable vulcanization rate and good adhesion in a balanced manner and maintaining appropriate concentration. It is preferably a branched alkyl group having 3 to 10 carbon atoms, more preferably 3 to 6 carbon atoms, branched by an α-position carbon atom of the nitrogen atom, specifically an isopropyl group, a sec-butyl group, Examples include 1-methylpentyl group. By appropriately selecting R ² together with R ¹ as described above, the bulk height of the substituent located in the vicinity of —N— is effectively controlled, and the vulcanization rate is suitable while considering human body accumulation. And good adhesion performance can be exhibited in a well-balanced manner.

Therefore, if R ² in the above formula (I) is a conventional sulfenamide vulcanization accelerator such as H, the vulcanization speed may be too high and good adhesiveness tends not to be obtained. is there. Further, when R ² is a conventional sulfenamide vulcanization accelerator such as a cyclohexyl group or a long chain group outside the above range, the vulcanization rate tends to be too slow. .

More specifically, particularly when R ¹ is a tert-butyl group and n is 0, among R ² having the above carbon number, the optimum branched alkyl group is the same as that of improved adhesion and DCBS. From the viewpoint of exhibiting the effect of maintaining the vulcanization rate in a balanced manner, isopropyl group and sec-butyl group are exemplified.

Furthermore, particularly when R ¹ is a tert-butyl group and n is 0, R ² having the above carbon number is more preferably a linear alkyl group than a branched alkyl group. From the standpoint of improving the properties and maintaining the vulcanization rate equivalent to that of DCBS in a well-balanced manner and taking into consideration human body accumulation properties, a methyl group and an ethyl group are exemplified. When both R ¹ and R ² are branched alkyl groups, the stability after production tends to be inferior, and when R ¹ and R ² are both tert-butyl groups, they cannot be synthesized.

In the sulfenamide vulcanization accelerator represented by the above formula (I), R ¹ is a functional group other than a branched alkyl group having 3 to 12 carbon atoms (for example, n-octadecyl group, etc.) or carbon number. Is a branched alkyl group having more than 12, and R ² is a linear group having 1 to 10 carbon atoms or a functional group other than a linear or branched alkyl group (for example, n-octadecyl group) or a linear chain having more than 10 carbon atoms. Or when it is a branched alkyl group, and when n is 2 or more, the intended effect of the present invention cannot be fully exerted, and the Mooney scorch time is delayed beyond the preferred range, and the vulcanization time is longer than necessary. If the length is too long, productivity and adhesiveness may decrease, or vulcanization performance and rubber performance as an accelerator may decrease.

R ^{3 to} R ⁶ in the above formula (I) are a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms or an alkoxy group, or a branched alkyl group having 3 to 4 carbon atoms or an alkoxy group. They may be the same or different. Among them, R ³ and R ⁵ are each a linear alkyl group or alkoxy group having 1 to 4 carbon atoms, or a branched alkyl group or alkoxy group having 3 to 4 carbon atoms. Preferably there is. Further, R ³ to R ⁶ are the alkyl group or alkoxy group having 1 to 4 carbon atoms, preferably 1 carbon atoms, preferably all R ³ to R ⁶ are H. In any preferred case, it is desirable in terms of the ease of synthesis of the compound and the slowing of the vulcanization rate. Specific examples of R ^{3 to} R ^{6 in} the above formula (I) include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, Examples include methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, sec-butoxy group, and tert-butoxy group.

Further, the log Pow value (1-octanol / water partition coefficient) of the sulfenamide-based vulcanization accelerator is preferably as small as possible from the viewpoint of maintaining appropriate concentration, and specifically, in the above formula (I) As the number of carbon atoms of R ¹ and R ² is smaller, the log Pow value tends to be smaller. For example, when R ¹ in the formula (I) used in the present invention is a t-butyl group and n is 0, a vulcanization rate equivalent to that of DCBS which is a conventional sulfenamide vulcanization accelerator is obtained. From the viewpoint of exhibiting good adhesion performance while maintaining and considering human body accumulation, R ² in formula (I) has 1 to 4 carbon atoms, more preferably 1 to 3 carbon atoms, most preferably 1 to 1 carbon atoms. Preferably, it is a linear alkyl group of 2.

The log Pow value (1-octanol / water partition coefficient) is generally a value obtained by one of the simple measuring methods for evaluating the concentration of chemical substances, and is in two solvent phases of 1-octanol and water. It means a value obtained from the chemical substance concentration ratio Pow in the two phases when a chemical substance is added to achieve a parallel state. Pow is expressed by the following equation, and the logarithmic value of Pow is the log Pow value.
Pow = Co / Cw
Co: Test substance concentration in the 1-octanol layer
Cw: Test substance concentration in water layer The log Pow value can be determined by measuring Pow using high performance liquid chromatography in accordance with JIS Z7260-117 (2006).

  In the present invention, typical examples of the sulfenamide-based vulcanization accelerator represented by the above formula (I) include N-methyl-Nt-butylbenzothiazole-2-sulfenamide (BMBS), N- Ethyl-Nt-butylbenzothiazole-2-sulfenamide (BEBS), Nn-propyl-Nt-butylbenzothiazole-2-sulfenamide, N-isopropyl-Nt-butylbenzothiazole -2-sulfenamide, Nn-butyl-Nt-butylbenzothiazole-2-sulfenamide (BBBS), N-isobutyl-Nt-butylbenzothiazole-2-sulfenamide, N- sec-Butyl-Nt-butylbenzothiazole-2-sulfenamide, N-methyl-N-isoamylbenzothiazole-2-sulfenamide Amides, N-ethyl-N-isoamylbenzothiazole-2-sulfenamide, Nn-propyl-N-isoamylbenzothiazole-2-sulfenamide, N-isopropyl-N-isoamylbenzothiazole-2-sulfenamide Amide, Nn-butyl-N-isoamylbenzothiazole-2-sulfenamide, N-isobutyl-N-isoamylbenzothiazole-2-sulfenamide, N-sec-butyl-N-isoamylbenzothiazole-2- Sulfenamide, N-methyl-N-tert-amylbenzothiazole-2-sulfenamide, N-ethyl-N-tert-amylbenzothiazole-2-sulfenamide, Nn-propyl-N-tert- Amylbenzothiazole-2-sulfenamide, N-isopropyl Pill-N-tert-amylbenzothiazole-2-sulfenamide, Nn-butyl-N-tert-amylbenzothiazole-2-sulfenamide, N-isobutyl-N-tert-amylbenzothiazole-2- Sulfenamide, N-sec-butyl-N-tert-amylbenzothiazole-2-sulfenamide, N-methyl-N-tert-heptylbenzothiazole-2-sulfenamide, N-ethyl-N-tert- Heptylbenzothiazole-2-sulfenamide, Nn-propyl-N-tert-heptylbenzothiazole-2-sulfenamide, N-isopropyl-N-tert-heptylbenzothiazole-2-sulfenamide, N- n-butyl-N-tert-heptylbenzothiazole-2- Sulfenamide, N-isobutyl-N-tert-heptylbenzothiazole-2-sulfenamide, N-sec-butyl-N-tert-heptylbenzothiazole-2-sulfenamide;

  N-methyl-Nt-butyl-4-methylbenzothiazole-2-sulfenamide, N-methyl-Nt-butyl-4,6-dimethoxybenzothiazole-2-sulfenamide, N-ethyl- Nt-butyl-4-methylbenzothiazole-2-sulfenamide, N-ethyl-Nt-butyl-4,6-dimethoxybenzothiazole-2-sulfenamide, Nn-propyl-N- t-butyl-4-methylbenzothiazole-2-sulfenamide, Nn-propyl-Nt-butyl-4,6-dimethoxybenzothiazole-2-sulfenamide, N-isopropyl-Nt- Butyl-4-methylbenzothiazole-2-sulfenamide, N-isopropyl-Nt-butyl-4,6-dimethoxybenzothiazole-2-sulf Nn-butyl-Nt-butyl-4-methylbenzothiazole-2-sulfenamide, Nn-butyl-Nt-butyl-4,6-dimethoxybenzothiazole-2-sulfen Amide, N-isobutyl-Nt-butyl-4-methylbenzothiazole-2-sulfenamide, N-isobutyl-Nt-butyl-4,6-dimethoxybenzothiazole-2-sulfenamide, N- and sec-butyl-Nt-butyl-4-methylbenzothiazole-2-sulfenamide, N-sec-butyl-Nt-butyl-4,6-dimethoxybenzothiazole-2-sulfenamide, and the like. It is done. These may be used alone or in combination of two or more.

  Among these, N-methyl-Nt-butylbenzothiazole-2-sulfenamide (BMBS) and N-ethyl-Nt-butylbenzothiazole-2-sulfenamide are known from the viewpoint of improving adhesive performance. (BEBS), Nn-propyl-Nt-butylbenzothiazole-2-sulfenamide, N-isopropyl-Nt-butylbenzothiazole-2-sulfenamide, N-isobutyl-Nt- Butylbenzothiazole-2-sulfenamide and N-sec-butyl-Nt-butylbenzothiazole-2-sulfenamide are preferable, and N-methyl-Nt-butylbenzothiazole-2-sulfenamide ( BMBS), N-ethyl-Nt-butylbenzothiazole-2-sulfenamide (BEBS), N-isopropyl N-t-butyl-2-sulfenamide, N-sec-butyl -N-t-butyl-2-sulfenamide are most preferable.

  In particular, N-methyl-Nt-butylbenzothiazole-2-sulfenamide (BMBS), N-ethyl-Nt-butylbenzothiazole- has the longest Mooney scorch time and excellent adhesion performance. 2-sulfenamide (BEBS) is optimal.

  These sulfenamide vulcanization accelerators include N-tert-butyl-2-benzothiazole sulfenamide (TBBS), N-cyclohexyl-2-benzothiazole sulfenamide (CBS), dibenzothiazolyl disulfide (MBTS). ) And other general-purpose vulcanization accelerators.

  Content of the said sulfenamide type | system | group vulcanization accelerator is 0.1-10 mass parts with respect to 100 mass parts of rubber components, Preferably it is 0.3-5.0 mass parts, More preferably, it is 0.5-2. .5 parts by mass. If the content of the vulcanization accelerator is less than 0.1 parts by mass, the vulcanization may not be sufficiently performed. On the other hand, if the content exceeds 10 parts by mass, bloom will be a problem, which is not preferable.

  Preferred examples of the method for producing the sulfenamide-based vulcanization accelerator include the following methods.

  That is, N-chloroamine prepared in advance by reaction of a corresponding amine and sodium hypochlorite and bis (benzothiazol-2-yl) disulfide are reacted in an appropriate solvent in the presence of an amine and a base. If an amine is used as the base, neutralize and return to the free amine, then subject to appropriate post-treatment such as filtration, washing with water, concentration and recrystallization according to the properties of the resulting reaction mixture. Sulfenamide is obtained.

  Examples of the base used in this production method include starting amines used in excess, tertiary amines such as triethylamine, alkali hydroxides, alkali carbonates, alkali bicarbonates, sodium alkoxides, and the like. In particular, the reaction is carried out using excess raw material amine as a base or tertiary amine triethylamine, neutralizing the hydrochloride formed with sodium hydroxide, taking out the target product, and then removing the amine from the filtrate. A method of reuse is desirable.

As the solvent used in this production method, alcohol is desirable, and methanol is particularly desirable.
For example, in N-ethyl-Nt-butylbenzothiazole-2-sulfenamide (BEBS), an aqueous sodium hypochlorite solution was added dropwise to Nt-butylethylamine at 0 ° C. or lower and the oil layer was stirred for 2 hours. Was sorted. Bis (benzothiazol-2-yl) disulfide, Nt-butylethylamine and the oil layer described above were suspended in methanol and stirred for 2 hours under reflux. After cooling, the solution is neutralized with sodium hydroxide, filtered, washed with water, concentrated under reduced pressure, and recrystallized to obtain the target BEBS (white solid).

The 1,6-hexamethylene-sodium dithiosulfate dihydrate (HTS) represented by the above formula (II) used in the present invention provides a thermally stable crosslinked structure as compared with sulfur crosslinking. Acts as a heat-resistant crosslinking agent. Also, HTS is considered to undergo radical cleavage by heat to generate .S— (CH ₂ ) ₆ —S. Upon reaction and react with the metal surface and the double bond in the polymer.

  The blending amount of the HTS is 0.3 to 5 parts by mass, preferably 1.0 to 3.0 parts by mass with respect to 100 parts by mass of the rubber component. If the HTS content is less than 0.3 parts by mass, the effect of trapping the moisture cannot be sufficiently exhibited. If the content exceeds 5.0 parts by mass, unreacted in the rubber after vulcanization. Since the remaining amount increases, there is a possibility that the effect of enhancing the heat aging resistance by generating a stable cross-linked form that is characteristic of HTS may be impaired.

  Sulfur used in the present invention acts as a vulcanizing agent, and the content thereof is 0.3 to 10 parts by mass, preferably 1.0 to 7.0 parts by mass, with respect to 100 parts by mass of the rubber component. More preferably, the amount is 3.0 to 7.0 parts by mass. If the sulfur content is less than 0.3 parts by mass, vulcanization may not be achieved sufficiently. On the other hand, if it exceeds 10 parts by mass, the aging performance of the rubber may be lowered, which is not preferable.

  Furthermore, it is preferable that the rubber composition contains a cobalt-based component made of cobalt alone and / or a compound containing cobalt from the viewpoint of improving the initial adhesion performance. Examples of the cobalt-based component include cobalt alone, and compounds containing cobalt include cobalt salts of organic acids, cobalt salts of inorganic acids, cobalt chloride, cobalt sulfate, cobalt nitrate, cobalt phosphate, cobalt chromate At least one of them. Of these, the use of a cobalt salt of an organic acid is desirable from the viewpoint of further improving the initial adhesion performance. These cobalt simple substance and the compound containing cobalt may be used individually by 1 type, and may be used in mixture of 2 or more types.

  More specifically, examples of the cobalt salt of the organic acid include at least one of cobalt naphthenate, cobalt stearate, cobalt neodecanoate, cobalt rosinate, cobalt versatate, cobalt tall oilate, and the like. In addition, the organic acid cobalt may be a complex salt in which a part of the organic acid is replaced with boric acid. Specifically, a commercially available product name “Manobond” manufactured by OMG may be used.

The (total) content of the cobalt-based component is preferably 0.03 to 3 parts by mass, more preferably 0.03 to 1 part by mass with respect to 100 parts by mass of the rubber component (A) as the amount of cobalt. is there.
If the content of these cobalt amounts is less than 0.03 parts by mass, further adhesiveness cannot be exhibited. On the other hand, if it exceeds 3 parts by mass, the aging physical properties are greatly lowered, which is not preferable.

  The rubber composition of the present invention is usually used in rubber products such as tires and conveyor belts in addition to the rubber components, vulcanization accelerators, phenolic thermoplastic resins, methylene donors, sulfur and cobalt components. A compounding agent can be used in the range which does not inhibit the effect of this invention.

  For example, when a reinforcing filler is used, the fracture resistance and wear resistance can be further improved. Specific examples include carbon black or white inorganic filler.

  Examples of carbon black include channel black, furnace black, acetylene black, and thermal black depending on the production method, and any of them may be used, and examples thereof include SRF, GPF, FEF, HAF, ISAF, and SAF. Carbon black having an iodine adsorption amount (IA) of 60 mg / g or more and a dibutyl phthalate oil absorption amount (DBP) of 80 ml / 100 g or more is preferred.

On the other hand, as a white inorganic filler, what is represented by a silica and the following general formula (Y) is preferable.
mM ₁ · xSiO _y · zH ₂ O (Y)
(In formula (Y), M ₁ is at least one selected from metals selected from the group consisting of aluminum, magnesium, titanium and calcium, oxides or hydroxides of these metals, and hydrates thereof. , M, x, y and z are each an integer of 1 to 5, an integer of 0 to 10, an integer of 2 to 5, and an integer of 0 to 10). Furthermore, metals such as potassium, sodium, iron and magnesium, elements such as fluorine, and groups such as NH ₄ — may be contained.

Specifically, alumina monohydrate (Al ₂ O ₃ .H ₂ O), aluminum hydroxide such as gibbsite and bayerite [Al (OH) ₃ ], magnesium hydroxide [Mg (OH) ₂ ], oxidation Magnesium (MgO), talc (3MgO · 4SiO ₂ · H ₂ O), attapulgite (5MgO · 8SiO ₂ · 9H ₂ O), titanium white (TiO ₂ ), titanium black (TiO _2n-1 ), calcium oxide (CaO) Calcium hydroxide [Ca (OH) ₂ ], magnesium aluminum oxide (MgO.Al ₂ O ₃ ), clay (Al ₂ O ₃ .2SiO ₂ ), kaolin (Al ₂ O ₃ .2SiO ₂ .2H ₂ O), pyrophyllite _{(Al 2 O 3 · 4SiO 2} · H 2 O), bentonite _{(Al 2 O 3 · 4SiO 2} · 2H 2 O), aluminum silicate _{(Al 2 SiO 5, Al 4} · 3SiO 4 · H ₂ O, etc.), magnesium silicate (Mg ₂ SiO _4, MgSiO ₃ etc.), calcium silicate (Ca ₂ · SiO ₄ etc.), aluminum silicate calcium _{(Al 2 O 3 · CaO ·} 2SiO 2 etc.), silicic Examples thereof include magnesium calcium oxide (CaMgSiO ₄ ), various zeolites, feldspar, mica, montmorillonite and the like. M ₁ is preferably aluminum, and aluminas and clays are particularly preferable.

Among the aluminas represented by the above general formula (Y), the aluminas are those represented by the following general formula (Z).
Al ₂ O ₃ .nH ₂ O (where n is 0 to 3) (Z)
In clays, clay (Al ₂ O ₃ .2SiO ₂ ), kaolin (Al ₂ O ₃ .2SiO ₂ .2H ₂ O), pyrophyllite (Al ₂ O ₃ .4SiO ₂ .H ₂ O), bentonite (Al ₂ O ₃ .4SiO ₂ .2H ₂ O), montmorillonite and the like.

  Among these white inorganic fillers, silica and aluminum hydroxide are preferable, and silica is particularly preferable. Here, the silica is appropriately selected from those conventionally used for reinforcing rubber, such as wet method silica (hydrous silicic acid), dry method silica (anhydrous silicic acid), and various silicates. Among them, synthetic silica by a precipitation method (wet method silica) is preferable.

  These reinforcing fillers can be blended in a proportion of 10 to 120 parts by mass, preferably 20 to 100 parts by mass, with respect to 100 parts by mass of the rubber component.

  Further, when a white inorganic filler such as silica is used as the reinforcing filler, a coupling agent may be blended if desired. The coupling agent is not particularly limited, and any one of various conventionally known coupling agents can be selected and used. Among these, a silane coupling agent is particularly preferable. Examples of the silane coupling agent include bis (3-triethoxysilylpropyl) tetrasulfide, bis (3-trimethoxysilylpropyl) tetrasulfide, bis (3-methyldimethoxysilylpropyl) tetrasulfide, bis (3 -Triethoxysilylethyl) tetrasulfide, bis (3-triethoxysilylpropyl) disulfide, bis (3-trimethoxysilylpropyl) disulfide, bis (3-triethoxysilylpropyl) trisulfide, 3-mercaptopropyltrimethoxysilane 3-mercaptopropyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-mercaptopropylmethyldi Toxisilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, 3-trimethoxysilylpropyl-N, N-dimethylcarbamoyl tetrasulfide, 3-trimethoxysilylpropylbenzothiazolyltetra Examples thereof include sulfide and 3-trimethoxysilylpropylmethacryloyl monosulfide.

  The said coupling agent may be used individually by 1 type, and may be used in combination of 2 or more type. Moreover, the compounding quantity is 1-20 mass% with respect to the said white inorganic filler, when it considers a mixing effect, economical efficiency, etc., Preferably it is the quantity of 5-20 mass%.

  Moreover, as other compounding agents other than the above, for example, a softening agent, an anti-aging agent and the like can be mentioned, and these can be appropriately blended according to applications.

  The rubber composition of the present invention can be produced by kneading each of the above components with a Banbury mixer, a kneader or the like. Further, when manufacturing tires for passenger cars, trucks, buses, motorcycles, etc. using the rubber composition of the present invention, a bead filler member or a side reinforcing rubber for run flat tires is prepared by an extruder or a calendar, for example. It is also possible to produce a green tire by pasting these with other members on a molding drum, etc., and placing the green tire in a tire mold and vulcanizing while applying pressure from the inside. it can. In addition to the air, the tire may be filled with nitrogen or an inert gas. Thus, it can be suitably used not only for tires using steel cords as reinforcements but also for rubber articles such as conveyor belts.

EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples.
In addition, as above-mentioned, the log Pow value of each sulfenamide type | system | group vulcanization accelerator calculated | required by measuring Pow using a high performance liquid chromatography based on JISZ7260-117 (2006).

[Production Example 1: Synthesis of N-methyl-Nt-butylbenzothiazole-2-sulfenamide (vulcanization accelerator 1)]
To 14.1 g (0.162 mol) of Nt-butylmethylamine, 148 g of a 12% aqueous sodium hypochlorite solution was added dropwise at 0 ° C. or lower, and after stirring for 2 hours, the oil layer was separated. Bis (benzothiazol-2-yl) disulfide (39.8 g, 0.120 mol), Nt-butylmethylamine (24.3 g, 0.240 mmol) and the oil layer described above were suspended in 120 ml of methanol and refluxed. Stir for 2 hours. After cooling, the solution was neutralized with 6.6 g (0.166 mol) of sodium hydroxide, filtered, washed with water, concentrated under reduced pressure, and then recrystallized to obtain 46.8 g (yield 82%) of the target BMBS as a white solid. (Melting point 56-58 ° C., log Pow value 4.5).

¹ H-NMR (400 MHz, CDCl ₃ ) δ = 1.32 (9H, s, CH ₃ (t-butyl)), 3.02 (3H, s, CH ₃ (methyl)), 7.24 (1H, m), 7.38 (1H, m), 7.77 (1H, m), 7.79 (1H, m).
¹³ C-NMR (100 MHz, CDCl ₃ ) δ = 27.3, 41.9, 59.2, 120.9, 121.4, 123.3, 125.7, 135.0, 155.5, 180. 8).
Mass spectrometry (EI, 70 eV) m / z; 252 (M ⁺ ), 237 (M ⁺ -CH ₃ ), 223 (M ⁺ -C ₂ H ₆ ), 195 (M ⁺ -C ₄ H ₉ ), 167 ( _{^{M + -C 5 H 12 N)}} , 86 (M + -C 7 H 4 NS 2).

[Production Example 2: Synthesis of N-ethyl-Nt-butylbenzothiazole-2-sulfenamide (BEBS, vulcanization accelerator 2)]
The same procedure as in Production Example 1 was carried out using 16.4 g (0.162 mol) of Nt-butylethylamine instead of Nt-butylmethylamine, and 41.9 g (66% yield) of BEBS as a white solid ( Melting point was 60 to 61 ° C. and log Pow value was 4.9).
The spectrum data of the obtained BEBS is shown below.

¹ H-NMR (400 MHz, CDCl ₃ ) δ = 1.29 (t, 3H, J = 7.1 Hz, CH ₃ (ethyl)), 1.34 (s, 9H, CH ₃ (t-butyl)), 2.9-3.4 (br-d, CH ₂ ), 7.23 (1H, m), 7.37 (1H, m), 7.75 (1H, m), 7.78 (1H, m ).
¹³ C-NMR (100 MHz, CDCl ₃ ) δ = 15.12, 28.06, 47.08, 60.41, 120.70, 121.26, 123.23, 125.64, 134.75, 154. 93, 182.63.
Mass spectrometry (EI, 70 eV): m / z; 251 (M ⁺ —CH ₄ ), 167 (M ⁺ —C ₆ H ₁₄ N), 100 (M ⁺ —C ₇ H ₅ NS ₂ ): IR (KBr, cm < ^-1 >): 3061, 2975, 2932, 2868, 1461, 1429, 1393, 1366, 1352, 1309, 1273, 1238, 1198, 1103, 1022, 1011, 936, 895, 756, 727.

[Production Example 3: Synthesis of Nn-propyl-Nt-butylbenzothiazole-2-sulfenamide (vulcanization accelerator 3)]
The same procedure as in Production Example 1 was carried out using 18.7 g (0.162 mol) of Nn-propyl-t-butylamine instead of Nt-butylmethylamine, and Nn-propyl-Nt-butylbenzo Thiazole-2-sulfenamide was obtained as a white solid (melting point 50-52 ° C., log Pow value 5.3).

¹ H-NMR (400 MHz, CDCl ₃ ) δ = 0.92 (t, J = 7.3 Hz, 3H), 1.34 (s, 9H), 1.75 (br, 2H), 3.03 (brd , 2H), 7.24 (t, J = 7.0 Hz, 1H), 7.38 (t, J = 7.0 Hz, 1H), 7.77 (d, J = 7.5 Hz, 1H), 7 .79 (d, J = 7.5 Hz, 1H).
¹³ C-NMR (100 MHz, CDCl ₃ ) δ = 11.7, 23.0, 28.1, 55.3, 60.4, 120.7, 121.3, 123.3, 125.7, 134. 7, 154.8, 181.3.

[Production Example 4: Synthesis of Ni-propyl-Nt-butylbenzothiazole-2-sulfenamide (vulcanization accelerator 4)]
The same procedure as in Production Example 1 was carried out using 18.7 g (0.162 mol) of Ni-propyl-t-butylamine instead of Nt-butylmethylamine, and Ni-propyl-Nt-butylbenzo was used. Thiazole-2-sulfenamide was obtained as a white solid (melting point 68-70 ° C., log Pow value 5.1).

¹ H-NMR (400 MHz, CDCl ₃ ) δ = 1.20-1.25 (dd, (1.22 ppm: J = 6.4 Hz, 1.23 ppm: J = 6.4 Hz) 6H), 1.37 ( s, 9H), 3.78 (m, J = 6.3 Hz, 1H), 7.23 (t, J = 7.0 Hz, 1H), 7.38 (t, J = 7.0 Hz, 1H), 7.77 (d, J = 7.5 Hz, 1H), 7.79 (d, J = 7.5 Hz, 1H).
¹³ C-NMR (100 MHz, CDCl ₃ ) δ = 22.3, 23.9, 29.1, 50.6, 61.4, 120.6, 121.2, 123.2, 125.6, 134. 5, 154.5, 183.3.

[Production Example 5: Synthesis of N, N-di-i-propylbenzothiazole-2-sulfenamide (vulcanization accelerator 5)]
N, N-di-i-propylbenzothiazole-2 was prepared in the same manner as in Production Example 1 using 16.4 g (0.162 mol) of N-di-i-propylamine instead of Nt-butylmethylamine. -Sulfenamide was obtained as a white solid (melting point 57-59 ° C).

¹ H-NMR (400 MHz, CDCl ₃ ) δ = 1.26 (d, J = 6.5 Hz, 12H), 3.49 (dq, J = 6.5 Hz, 2H), 7.24 (t, J = 7.0 Hz, 1H), 7.37 (t, J = 7.0 Hz, 1H), 7.75 (d, J = 8.6 Hz, 1H), 7.79 (d, J = 8.6 Hz, 1H) ).
¹³ C-NMR (100 MHz, CDCl ₃ ) δ = 21.7, 22.5, 55.7, 120.8, 121.3, 123.4, 125.7, 134.7, 155.1, 182. 2.
Mass spectrometry (EI, 70 eV), m / z 266 (M ⁺ ), 251 (M ⁺ −15), 218 (M ⁺ −48), 209 (M ⁺ −57), 182 (M ⁺ −84), 167 ( M ^<+>- 99), 148 (M ^<+ > ^- 118), 100 (M ^<+ > ^- 166: base).

[Production Example 6: Synthesis of Nn-butyl-Nt-butylbenzothiazole-2-sulfenamide (vulcanization accelerator 6)]
The same procedure as in Production Example 1 was carried out using 20.9 g (0.162 mol) of Nt-butyl-n-butylamine instead of Nt-butylmethylamine, and 42.4 g (yield 60%) of BBBS was obtained. Obtained as a white solid (melting point 55-56 ° C., log Pow value 5.8).

¹ H-NMR (400 MHz, CDCl ₃ ) δ = 0.89 (3H, t, J = 7.32 Hz, CH ₃ (n-Bu)), 1.2-1.4 (s + m, 11H, CH ₃ ( t-butyl) + CH ₂ (n-butyl)), 1.70 (br.s, 2H, CH ₂ ), 2.9-3.2 (br.d, 2H, N—CH ₂ ), 7.23 (1H, m), 7.37 (1H, m), 7.75 (1H, m), 7.78 (1H, m).
¹³ C-NMR (100 MHz, CDCl ₃ ) δ = 14.0, 20.4, 27.9, 31.8, 53.0, 60.3, 120.6, 121.1, 123.1, 125. 5, 134.6, 154.8, 181.2.
Mass spectrometry (EI, 70 eV), m / z 294 (M ⁺ ), 279 (M ⁺ —CH ₃ ), 237 (M ⁺ —C ₄ H ₉ ), 167 (M ⁺ —C ₈ H ₁₈ N), 128 ( M ⁺ -C ₇ H ₄ NS ₂ ): IR (neat): 1707 cm ⁻¹ , 3302 cm ⁻¹ .

[Examples 1 to 6]
Using a 2200 ml Banbury mixer, the rubber component, the vulcanization accelerator obtained in the above production example, HTS, sulfur, and other compounding agents were kneaded and mixed in the formulation shown in Table 1, and unvulcanized rubber A composition was prepared, Mooney viscosity and Mooney scorch time were measured by the following methods, and a tensile test and a dynamic storage elasticity test were performed according to the methods shown below and evaluated. The results are shown in Table 1.

[Examples 7 to 8]
A rubber composition was prepared and evaluated in the same manner as described above according to the blending amount of Example 2 except that the blending amount of the vulcanization accelerator in Example 2 was changed. The results are shown in Table 1.

[Comparative Example 1]
A rubber composition was prepared and evaluated according to Example 1 except that conventional vulcanization accelerator (DCBS) was used as the vulcanization accelerator and HTS was not blended. The results are shown in Table 1.

[Comparative Example 2]
A rubber composition was prepared and evaluated according to Example 1 except that a conventional vulcanization accelerator (DCBS) was used. The results are shown in Table 1.

[Examples 9 to 10]
A rubber composition was prepared and evaluated in the same manner as described above according to the amount of Example 2 except that natural rubber and SBR (styrene butadiene rubber) were blended and used as the rubber component. The results are shown in Table 2.

[Examples 11-14, Comparative Examples 3-4]
Natural rubber, BR (butadiene rubber) or SBR (styrene butadiene rubber) was appropriately blended as a rubber component, and a rubber composition was prepared and evaluated according to the formulation shown in Table 4. The results are shown in Table 4.

[Examples 15 to 18, Comparative Examples 5 to 6]
As a rubber component, natural rubber, BR (butadiene rubber) or SBR (styrene butadiene rubber) was appropriately blended, and a cobalt-based component was blended, and a rubber composition was prepared and evaluated according to the formulation shown in Table 5. The results are shown in Table 5.

<Evaluation method of Mooney viscosity and Mooney scorch time>
This was performed according to JIS K 6300-1: 2001.
The evaluation was expressed as an index with the value of Comparative Example 1 being 100. The smaller the value of Mooney viscosity, the better the workability during kneading, and the greater the Mooney scorch time, the better the workability after kneading.

<Evaluation method of tensile test>
A JIS dumbbell-shaped No. 3 sample composed of the obtained rubber composition was prepared and subjected to a tensile test at 25 ° C. in accordance with JIS K 6251: 2004. Elongation at break (Eb), Tensile strength at break ( Tb) was measured, and each value of the rubber composition of Comparative Example 1 was taken as 100 and indicated as an index. It shows that it is excellent in fracture resistance, so that an index value is large. Each rubber composition was aged in an atmosphere of 100 ° C. for 24 hours, and the elongation at break (Eb) and the tensile strength at break (Tb) after heat aging were measured and evaluated in the same manner as described above.

<Heat resistant adhesiveness>
Three steel cords (outer diameter 0.5 mm x length 300 mm) plated with brass (Cu: 63% by mass, Zu: 37% by mass) are arranged in parallel at 10 mm intervals, and each rubber composition is arranged from both the upper and lower sides. Then, this was vulcanized at 160 ° C. for 20 minutes to prepare a sample.
About each heat-resistant adhesiveness of each obtained sample, according to ASTM-D-2229, each sample was left in a gear oven at 100 ° C. for 15 days for 30 days, and then the steel cord was pulled out to visually check the rubber coating state. And displayed as 0 to 100% as an index of each heat resistant adhesiveness. It shows that it is excellent in heat resistant adhesiveness, so that a numerical value is large.

* 1: Product name: Seest 300, manufactured by Tokai Carbon Co., Ltd., nitrogen adsorption specific surface area 84 m ² / g, DBP oil absorption 75 ml / 100 g)
* 2: N-phenyl-N′-1,3-dimethylbutyl-p-phenylenediamine (NOCRACK 6C, manufactured by Ouchi Shinsei Chemical Co., Ltd.)
* 3: N, N'-dicyclohexyl-2-benzothiazylsulfenamide (Noxeller DZ, manufactured by Ouchi Shinsei Chemical Co., Ltd.)
* 4: N-cyclohexyl-2-benzothiazylsulfenamide (Noxeller CZ, manufactured by Ouchi Shinsei Chemical Co., Ltd.)
* 5: Nt-Butylbenzothiazole-2-sulfenamide (Noxeller NS, manufactured by Ouchi Shinsei Chemical Co., Ltd.)
* 6: 1,6-hexamethylene-sodium dithiosulfate dihydrate (Duralink HTS, manufactured by Flexis)
* 7: BR01
* 8: SBR # 1778
* 9: Product name: Manobond C22.5, manufactured by OMG, Cobalt content: 22.5% by mass

  As is apparent from the results of Tables 1 and 2, Examples 1 to 10 containing the specific vulcanization accelerator, HTS and sulfur are those containing conventional vulcanization accelerator (DCBS) and sulfur. As compared with Comparative Example 1 which does not contain any HTS, the fracture resistance is suppressed by suppressing the decrease in elongation at break, tensile strength at break and tensile stress at 50% elongation while maintaining good workability. It can be seen that the deterioration is prevented and the fracture resistance is well maintained even after the heat aging treatment.

Examples 1 to 6 and Comparative Example 2 each contain the same amount of the same HTS, but Examples 1 to 6 are compared to Comparative Example 2 using a conventional vulcanization accelerator (DCBS). In comparison, it can be seen that a suitable Mooney scorch time is exhibited while effectively suppressing an increase in Mooney viscosity. Further, it can be seen that the heat aging resistance is almost the same as or higher than that of Comparative Example 2.
Furthermore, as is clear from the results of Tables 3 to 4, Examples 15 to 18 containing a cobalt-based component have heat resistant adhesive properties while maintaining the above-mentioned favorable characteristics as compared with Examples 11 to 14. It turns out that it is excellent.

  Therefore, the rubber composition of the present invention is excellent in workability and tensile properties by containing HTS and sulfur in addition to a specific vulcanization accelerator having a vulcanization delay effect equal to or higher than that of DCBS, and has heat aging resistance. It is also excellent in properties and can significantly reduce the occurrence of rubber burns. Further, the adhesion performance can be further improved by further blending a cobalt-based component.

Claims (15)

It contains a rubber component, a sulfenamide-based vulcanization accelerator represented by formula (I), 1,6-hexamethylene-sodium dithiosulfate dihydrate represented by formula (II), and sulfur. A rubber composition characterized by:

(In formula (I), R ¹ represents a branched alkyl group having 3 to 12 carbon atoms, and R ² represents a linear alkyl group having 1 to 10 carbon atoms or a branched alkyl group having 3 to 10 carbon atoms. ^{3 to} R ⁶ are a hydrogen atom, a linear alkyl group or alkoxy group having 1 to 4 carbon atoms, or a branched alkyl group or alkoxy group having 3 to 4 carbon atoms, which may be the same as or different from each other. N represents 0 or 1, and x represents 1 or 2.)   The rubber composition according to claim 1, wherein the sulfenamide-based vulcanization accelerator is contained in an amount of 0.1 to 10 parts by mass with respect to 100 parts by mass of the rubber component.   The rubber composition according to claim 1 or 2, wherein the rubber component contains the 1,6-hexamethylene-sodium dithiosulfate dihydrate in an amount of 0.3 to 5 parts by mass with respect to 100 parts by mass of the rubber component. object.   The rubber composition according to any one of claims 1 to 3, wherein the sulfur component is contained in an amount of 0.3 to 10 parts by mass with respect to 100 parts by mass of the rubber component. The rubber composition according to claim 1, wherein, in the formula (I), R ¹ and R ² are branched alkyl groups having a branch at the α-position. The rubber composition according to claim 1, wherein in the formula (I), R ¹ is a tert-butyl group and n is 0. In the formula (I), R ¹ is a tert-butyl group, R ² is a linear alkyl group having 1 to 6 carbon atoms or a branched alkyl group having 3 to 6 carbon atoms, and R ^{3 to} R ⁶ are hydrogen. The rubber composition according to any one of claims 1 to 6, which is an atom. In the formula (I), R ¹ is a tert-butyl group, R ² is a linear alkyl group having 1 to 6 carbon atoms or a branched alkyl group having 3 to 6 carbon atoms, and R ^{3 to} R ⁶ are hydrogen. The rubber composition according to any one of claims 1 to 7, which is an atom and n is 0. In the formula (I), R ¹ is a tert-butyl group, R ² is a methyl group, an ethyl group or an n-propyl group, R ^{3 to} R ⁶ are hydrogen atoms, and n is 0. The rubber composition according to any one of claims 1 to 8. In the formula (I), R ¹ is a tert-butyl group, R ² is an ethyl group, R ^{3 to} R ⁶ are hydrogen atoms, and n is 0. The rubber composition as described in 2.   The rubber composition according to any one of claims 1 to 10, wherein the rubber composition further comprises a cobalt-based component composed of a simple cobalt and / or a compound containing cobalt.   The rubber composition according to claim 11, wherein the content of the cobalt-based component is 0.03 to 3 parts by mass with respect to 100 parts by mass of the rubber component as a cobalt amount.   The rubber composition according to claim 11 or 12, wherein the cobalt-containing compound is a cobalt salt of an organic acid.   The rubber composition according to any one of claims 1 to 13, wherein the rubber component contains at least one of natural rubber and polyisoprene rubber.   The rubber composition according to claim 14, comprising natural rubber in an amount of 50% by mass or more in 100% by mass of the rubber component.