WO2010126143A1

WO2010126143A1 - Tire

Info

Publication number: WO2010126143A1
Application number: PCT/JP2010/057709
Authority: WO
Inventors: 一晃難波
Original assignee: 株式会社ブリヂストン
Priority date: 2009-04-30
Filing date: 2010-04-30
Publication date: 2010-11-04

Abstract

Disclosed is a tire which satisfies strict requirements for higher loads, higher speeds and longer service life, shows excellent adhesion durability between a steel cord and a coating rubber and excellent cracking resistance in a belt layer even under severe conditions, and has excellent durability. Specifically disclosed is a tire (A) in which a belt layer (6) comprises a layer consisting of steel cords coated with a coating rubber, said tire being characterized in that a rubber composition comprising a rubber component, sulfur and a sulfenamide vulcanization accelerator represented by general formula (I) is used as the coating rubber for coating the steel cords in said belt layer (6). In general formula (I), R¹ represents a branched alkyl group having 3 to 12 carbon atoms; R² represents a straight-chain alkyl group having 1 to 10 carbon atoms; R³ to R⁶ may be the same or different and each represents a hydrogen atom, a straight-chain alkyl or alkoxy group having 1 to 4 carbon atoms, or a branched alkyl or alkoxy group having 3 to 4 carbon atoms; x represents an integer of 1 or 2; and n represents an integer of 0 or 1.

Description

tire

The present invention relates to a tire having a steel cord and a belt layer made of a coating rubber covering the steel cord, and more particularly, a rubber having excellent deterioration characteristics as a coating rubber for the belt layer and excellent adhesion to the steel cord. The present invention relates to a tire having excellent durability using the composition as a coating rubber for a belt layer.

Conventionally, the performance required for automobile tires has become increasingly severe, and further improvements in tire durability are desired. Furthermore, in recent years, tires are required to have a heavier load, higher speed, and higher life in order to increase efficiency.

The belt member of tires from passenger cars to industrial large-sized tires is generally made of a metal and a coating rubber covering its cord. The required performance of the coating rubber for the belt includes that the crack does not easily develop and that the adhesiveness of the rubber-steel cord can be secured against the thermal history.
In steel cord reinforced tires with a belt layer, if the tire is used under heavy load and high speed, the decrease in adhesion between the rubber and steel cord of the belt layer is promoted, resulting in a problem in tire durability. It has been known.
In a tire having a belt layer reinforced with this steel cord, securing the adhesion between the steel cord and the coating rubber covering the cord has been a very important issue. Various studies have been made to improve the heat-resistant adhesion and durability.

For example, it is possible to achieve both low heat build-up and heat aging resistance without causing a decrease in the adhesion between the steel cord and rubber, and especially the steel in the belt layer of a tire that is subjected to high heat and high strain conditions. As a rubber covering the cord, 35 to 50 parts by weight of carbon black, 3 to 15 parts by weight of silica (white carbon), 100 parts by weight of ethylene glycol with respect to 100 parts by weight of a rubber component mainly composed of natural rubber or synthetic natural rubber 0.1 to 3.0 parts by weight of zinc glycol, diethylene glycol, triethylene glycol, polyethylene glycol, 0.1 to 3.0 parts by weight, zinc monomethacrylate or zinc dimethacrylate 0 A rubber composition for coating a steel cord is known, characterized in that .05 to 0.8 parts by weight are blended (for example, Patent Document 1). Irradiation).

However, even if the technique described in Patent Document 1 is used, there is still a problem in that it is still insufficient for the needs that require a heavier load, higher speed, and higher life. At present, tires that are excellent in the durability of bonding between the cord and the coating rubber and excellent in the durability are desired.

Japanese Patent Laid-Open No. 5-51491 (Claims, Examples, etc.)

The present invention intends to solve this problem in view of the above-described problems of the prior art and the current situation, and satisfies the demands for higher loads, higher speeds, and higher lifespans. An object of the present invention is to provide a tire having excellent durability of adhesion between a steel cord and a coating rubber in a belt layer even under conditions, and excellent durability.

As a result of intensive studies on the above-described conventional problems and the like, the inventor has a tire having a steel cord and a belt layer made of a coating rubber covering the steel cord, the coating covering the steel cord of the belt layer. By using a rubber composition having specific physical properties as the rubber, it was found that the above-mentioned tire can be obtained, and the present invention has been completed.

That is, the present invention resides in the following (1) to (22).
(1) A tire having a steel cord and a belt layer made of a coating rubber covering the steel cord, wherein the coating rubber covering the steel cord of the belt layer includes a rubber component, sulfur, and the following general formula ( A tire comprising a rubber composition containing a sulfenamide vulcanization accelerator represented by I).

(2) The rubber composition contains 0.1 to 10 parts by mass of the sulfenamide vulcanization accelerator represented by the general formula (I) with respect to 100 parts by mass of the rubber component. ) Tire.
(3) The tire according to (1), wherein the rubber composition contains 0.3 to 10 parts by mass of sulfur with respect to 100 parts by mass of the rubber component.
(4) The rubber composition contains 0.3 to 10 parts by mass of sulfur with respect to 100 parts by mass of the rubber component and 0.1 to 10 parts of the sulfenamide vulcanization accelerator represented by the above general formula (I). The tire according to (1), comprising a mass part.
(5) The tire according to (1), wherein R ¹ in the general formula (I) is a tert-alkyl group and n = 0.
(6) In the general formula (I), R ¹ is a tert-butyl group, R ² is a linear alkyl group having 1 to 6 carbon atoms, and R ³ to R ⁶ are hydrogen atoms. The tire according to (1) above.
(7) In the general formula (I), R ¹ is a tert-butyl group, n = 0, R ² is a linear alkyl group having 1 to 6 carbon atoms, and R ³ to R ⁶ Is a tire as described in said (1) which is a hydrogen atom.
(8) R ¹ in the general formula (I) is a tert-butyl group, n = 0, R ² is a methyl group, an ethyl group, or an n-propyl group, and R ³ to R ⁶ are The tire according to (1), which is a hydrogen atom.
(9) The tire according to any one of (1) to (8), wherein the rubber composition further contains cobalt and / or a compound containing cobalt.
(10) The tire according to (9), wherein the content of cobalt and / or a compound containing cobalt is 0.03 to 3 parts by mass with respect to 100 parts by mass of the rubber component as the amount of cobalt.
(11) The tire according to (9) or (10), wherein the cobalt-containing compound is a cobalt salt of an organic acid.
(12) The tire according to any one of (1) to (11), wherein the rubber component of the rubber composition contains at least one of natural rubber and polyisoprene rubber.
(13) The tire according to any one of (1) to (11) above, wherein the rubber component of the rubber composition is 50% by mass or more of natural rubber and the balance is made of synthetic rubber.
(14) The rubber component of the rubber composition according to any one of (1) to (11) above, wherein the rubber component is made of isoprene rubber and transpolybutadiene and contains N, N′-diphenylmethane bismaleimide. tire.
(15) The tire according to (14), wherein the belt layer includes a steel cord layer group embedded with four or more coating rubbers, and includes at least a pair of crossing layers in the steel cord layer group.
(16) The total weight part of the weight of the N, N′-diphenylmethane bismaleimide and the weight of the trans polybutadiene is 10 or less, and the weight of the trans polybutadiene is 25% or more and 95% or less of the total weight of the two. The tire according to (14) or (15) above.
(17) The total weight part of the weight of the N, N′-diphenylmethane bismaleimide and the weight of the trans polybutadiene is 6 or less, and the weight of the trans polybutadiene is 25% or more and 95% or less of the total weight of the two. The tire according to (14) or (15) above.
(18) The total weight part of the weight of the N, N′-diphenylmethane bismaleimide and the weight of the trans polybutadiene is 6 or less, and the weight of the trans polybutadiene is 25% or more and 75% or less of the total weight of the two. The tire according to (14) or (15) above.
(19) The content of the N, N′-diphenylmethane bismaleimide is 0.1 to 4 parts by mass with respect to 100 parts by mass of the rubber component, as described in any one of (14) to (18) above Tires.
(20) The tire according to any one of (14) to (19), wherein the tire is a tire for a large vehicle.
(21) After the vulcanization, the coating rubber has a tensile stress at 100% elongation of 3.5 MPa or more and a tan δ of 0.200 or less when immediately applied under the condition of 2% strain at 25 ° C. The tire according to any one of the above (14) to (19).
(22) The tire according to any one of (14) to (21), wherein the trans polybutadiene has a trans bond content of 82 to 98 mol% and a weight average molecular weight of 30,000 to 200,000. .

According to the present invention, it becomes satisfactory even for the demands of higher loads such as higher load, higher speed, and higher life, and even under harsh conditions, the heat resistance adhesion and resistance between the steel cord and the coating rubber in the belt layer. The tire is excellent in cracking property, and a tire excellent in durability is provided.

It is a transverse cross section showing an example of an embodiment of a tire of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view showing an example of an embodiment of a tire of the present invention.
As shown in FIG. 1, the tire A of the present embodiment includes a tread portion 1, a pair of sidewall portions 2 extending radially inward from the side portions of the tread portion 1, and a radius of the sidewall portion 2. One or more sheets disposed on the outer side in the tire radial direction of the crown part of the carcass 4, a bead part 3 connected to the inner end in the direction, a body part extending in a toroidal manner between the respective bead cores 5 disposed in each bead part 3 The belt layer 6 having a steel cord, which is composed of two

belt layers

6 and 6 in this embodiment, is not limited to the number of belt layers in the tire of the present invention.

The tire A of the present embodiment has a tire skeleton structure, and the carcass 4 that reinforces the tread portion 1, the sidewall portion 2, and the bead portion 3 of the tire is configured by one or more carcass plies. The carcass 4 in FIG. 1 is composed of one carcass ply. However, in the tire of the present invention, the number of carcass plies may be plural, and the structure is not particularly limited. .

The tire A of the present embodiment includes a steel cord layer in which the belt layer 6 is coated with a coating rubber. That is, at least one belt layer 6 may be a steel cord layer, and one or more belt layers may be a steel cord layer.

The steel cord used for the belt layer 6 is not particularly limited in material, number, twisted structure, etc., and is used for a tire belt layer for passenger cars to large-sized [trucks / buses (TB), construction vehicles (OR)]. Various steel cords can be used. Also, the configuration of the belt layer 6 is not particularly limited, and it is possible to employ a belt layer that has each configuration of tires for passenger cars to large-sized [trucks / buses (TB), construction vehicles (OR)]. it can.

In the present invention, the coating rubber that covers the steel cord of the belt layer 6 of the tire A contains a rubber component, sulfur, and a sulfenamide-based vulcanization accelerator represented by the following general formula (I). The rubber composition is used.

The rubber component in the rubber composition used for the coating rubber for coating the steel cord of the belt layer 6 is not particularly limited as long as it exhibits rubber elasticity, but in addition to natural rubber, vinyl aromatic hydrocarbon / conjugated diene. All known rubbers such as copolymers, polyisoprene rubber, butadiene rubber, butyl rubber, halogenated butyl rubber, and synthetic rubber such as ethylene-propylene rubber can be used. The rubber component may be used alone or in combination of two or more. From the viewpoint of adhesion characteristics with steel cords and fracture characteristics of the rubber composition, the rubber component is composed of at least one of natural rubber and polyisoprene rubber, or contains 50% by mass or more of natural rubber, with the balance being synthetic rubber. It is preferable.

Although there is no restriction | limiting in particular as sulfur contained in the rubber composition used for the said belt layer, Usually powder is used. The content of sulfur contained in the rubber composition for coating rubber is in the range of 0.3 to 10 parts by mass, preferably in the range of 3 to 8 parts by mass with respect to 100 parts by mass of the rubber component.
When the sulfur content is 0.3 parts by mass or more with respect to 100 parts by mass of the rubber component, it is preferable in terms of adhesiveness to the steel cord, and when it is 10 parts by mass or less, an excessive adhesive layer is generated. Since it is suppressed, adhesiveness is not lowered, which is preferable.

The compound represented by the general formula (I) contained in the rubber composition used for the belt layer has a vulcanization retarding effect equivalent to that of N, N-dicyclohexyl-2-benzothiazolylsulfenamide, and It is excellent in adhesion durability in direct vulcanization adhesion to a metal reinforcing material such as a steel cord, and is suitably used for a rubber composition for coating a belt layer having a steel cord.
Further, among the sulfenamide vulcanization accelerators represented by the above general formula (I), in particular, R ¹ is a tert-butyl group, x = 1 or 2, n = 0, ² is more preferably a straight chain, but among the straight chains, a methyl group, an ethyl group, an n-propyl group, and an n-butyl group are preferable, and a methyl group and an ethyl group are most preferable, and R ³ to R ⁶ are preferable. It is most preferable to use a sulfenamide compound, which is a hydrogen atom, as a vulcanization accelerator in terms of adhesion and vulcanization delay effect. These sulfenamide vulcanization accelerators are used as vulcanization accelerators for the first time in the present invention, and are the slowest in the vulcanization reaction among the conventional sulfenamide vulcanization accelerators. N, N-dicyclohexyl-2-benzothiazolylsulfenamide, which is known as a vulcanization accelerator that gives a sufficient vulcanization retarding effect, and has both sufficient vulcanization promoting ability and steel cord Excellent adhesion durability in direct vulcanization bonding with metal reinforcing materials such as Therefore, it is suitably used for a rubber composition for coating or the like having excellent adhesion durability in direct vulcanization adhesion with the steel cord of the belt layer of the tire of the present invention.

In the present invention, R ¹ in the sulfenamide compound represented by the general formula (I) represents a branched alkyl group having 3 to 12 carbon atoms. If R ¹ is a branched alkyl group having 3 to 12 carbon atoms, the vulcanization acceleration performance of the compound represented by the general formula (I) is good and the adhesion performance can be enhanced.
Specific examples of R ¹ of the compound represented by the general formula (I) include isopropyl group, isobutyl group, triisobutyl group, sec-butyl group, tert-butyl group, isoamyl group (isopentyl group), neopentyl group, tert-amyl group (tert-pentyl group), 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, from the viewpoint of vulcanization speed, adhesiveness, human body accumulation property, etc., R ¹ preferably has a branch at the α-position, and more preferably, from the viewpoint of effects such as obtaining a suitable scorch time. A tert-alkyl group having 3 to 12 carbon atoms is preferred, and in particular, tert-butyl group, tert-amyl group (tert-pentyl group), tert-dodecyl group, among which tert-butyl group is preferred from the viewpoint of synthesis and raw material acquisition It is economically excellent, and also provides a vulcanization rate equivalent to that of DCBS (DZ) and is particularly desirable from the viewpoint of further adhesion.

R ² in the sulfenamide compound represented by the general formula (I) represents a linear alkyl group having 1 to 10 carbon atoms. When R ² is a linear alkyl group having 1 to 10 carbon atoms, the vulcanization acceleration performance of the compound represented by the general formula (I) is good and the adhesion performance can be enhanced.
Specific examples of R ² of the compound represented by the general formula (I) include methyl group, ethyl group, n-propyl group, n-butyl group, n-amyl group (n-pentyl group), n-hexyl. Group, n-heptyl group, n-octyl group, nonyl group, decyl group and the like. Among these, from the viewpoint of effects such as ease of synthesis and raw material costs, a straight-chain alkyl group having 1 to 8 carbon atoms, and further a straight-chain alkyl group having 1 to 6 carbon atoms is preferable. Group, n-propyl group and n-butyl group are preferred.
Particularly preferably, a straight-chain alkyl group having 1 to 6 carbon atoms is desirable in that a suitable Mooney scorch time can be obtained and high steel cord adhesion can be obtained. This is because when the number of carbons increases, the vulcanization is further delayed, so that productivity is lowered and adhesiveness is lowered. Among these, a methyl group, an ethyl group, an n-propyl group, and an n-butyl group, which are linear alkyl groups having 4 or less carbon atoms, are most desirable.
In addition, R ³ to R ⁶ in the sulfenamide compound represented by the general formula (I) are a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms or an alkoxy group, and a branched one having 3 to 4 carbon atoms. An alkyl group or an alkoxy group, which 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 group having 3 to 4 carbon atoms. It is preferably a branched alkyl group or alkoxy group. In addition, when R ³ to R ⁶ are an alkyl group or alkoxy group having 1 to 4 carbon atoms, it is preferably 1 carbon atom, and particularly preferably a hydrogen atom. This is because in any case, the ease of synthesis of the compound and the vulcanization rate do not slow down.
Specific examples of R ³ to R ⁶ of the sulfenamide compound represented by the general formula (I) include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec- Examples thereof include a butyl group, a tert-butyl group, a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, a sec-butoxy group, and a tert-butoxy group.

When R ¹ and R ² in the sulfenamide compound represented by the general formula (I) are both branched alkyl groups, the difficulty of synthesis increases, and a stable compound is difficult to synthesize. In particular, when R ¹ and R ² are both tert-butyl groups, the synthesis is not successful. Moreover, when both R ¹ and R ² are branched alkyl groups, the heat resistant adhesiveness is deteriorated, which is not preferable. In the present invention, R ¹ in the sulfenamide compound represented by the general formula (I) is a branched alkyl group having 3 to 12 carbon atoms, and R ² is a linear alkyl group having 1 to 10 carbon atoms. In this combination, a unique effect of the present invention which has not been obtained so far is exhibited.
As a particularly preferred combination of R ¹ and R ^{2 in} the sulfenamide compound represented by the above general formula (I), R ¹ is a tert-butyl group, and R ² is a linear alkyl having 1 to 10 carbon atoms. The groups R ³ to R ⁶ are a combination of hydrogen atoms. Among these combinations, the best mode combination is when R ¹ is a tert-butyl group and R ² is a methyl group, ethyl group, n-propyl group, or n-butyl group having 4 or less carbon atoms. More preferably, in the case of this combination in which R ² has 3 or less carbon atoms, particularly preferably 2 or less carbon atoms, the vulcanization speed is equivalent to that of DCBS (DZ), further ensuring adhesion performance, and human body accumulation The best balance of performance from the viewpoint of.
The combination which becomes the best mode can be confirmed from the numerical value of the octanol / water partition coefficient (log POW) which is one of simple measures for evaluating the condensability of chemicals. In the present invention, the smaller the value of logP, the better the balance between the vulcanization speed, adhesion performance securing, and human body accumulation.
In the present invention (including the examples described later), the octanol / water partition coefficient (log P) can be measured by a high performance liquid chromatography method in accordance with JIS Z 7260-117 (2006). Is defined by the following equation.
logP = log ("Co" / "Cw")
Co: Test substance concentration in 1-octanol layer Cw: Test substance concentration in water layer

In the sulfenamide compound represented by the above general formula (I), x represents an integer of 1 or 2, and n represents an integer of 0 or 1, which is advantageous in terms of effects such as ease of synthesis and raw material costs. In view of this, n is preferably 0.
As described above, when the more preferable compounds among the sulfenamide compounds represented by the general formula (I) used in the present invention are further summarized in order, specifically, the Mooney scorch time is faster. 1) R ¹ of the above general formula (I) is a tert-butyl group, and n = 0, R ² is a linear alkyl group having 1 to 10 carbon atoms, R ³ to R ⁶ are hydrogen atoms, 2) R ¹ in the above general formula (I) is a tert-butyl group N is an integer of 0 or 1, R ² is a linear alkyl group having 1 to 6 carbon atoms, and R ³ to R ⁶ are hydrogen atoms, 3) In the above general formula (I) of ^{R 1} is tert- butyl group, a n = 0, ^{R 2} is C 1 -C 6 is a straight-chain alkyl ^group, R 3 ~ ^{R 6} are are hydrogen atoms, 4) ^{R 1} in the general formula (I) is a tert- butyl group, a n = 0, R ² is a straight-chain alkyl group having 4 or less carbon atoms (preferably a straight-chain alkyl group having 3 or less carbon atoms), and R ³ to R ⁶ are hydrogen atoms, 5) in the above general formula (I) R ¹ is a tert-butyl group, n = 0, R ² is a linear alkyl group having 2 or less carbon atoms (methyl group, ethyl group), and R ³ to R ⁶ are hydrogen atoms (The more descending, the more suitable the sulfenamide compound).
In the sulfenamide compound represented by the general formula (I), R ¹ is a functional group other than a branched alkyl group having 3 to 12 carbon atoms (for example, an n-octadecyl group) or 12 carbon atoms. When it is a branched alkyl group exceeding 1, or when R ² is a functional group other than a linear alkyl group having 1 to 10 carbon atoms (eg, n-octadecyl group) or a linear alkyl group exceeding 10 carbon atoms Further, when R ³ to R ⁶ are outside the range of each functional group and carbon number outside the above range, and when n is 2 or more, the effects of the object of the present invention are rarely exhibited. , The preferable Mooney scorch time becomes slow and the vulcanization time becomes long, resulting in a decrease in productivity, adhesion, or vulcanization performance and rubber performance as an accelerator. . Further, when x is 3 or more, it is not preferable in terms of stability. Further, when R ¹ in the sulfenamide compound represented by the above general formula (I) is a branched alkyl group, it has a branch other than the α-position, for example, 2-ethylhexyl, 2-ethylbutyl, etc. Therefore, it is desirable that there is a branch at the α position because the balance between vulcanization speed, adhesion performance securing, and human body accumulation tends to deteriorate.

In the present invention, representative examples of the compound represented by the general formula (I) include N-methyl-Nt-butylbenzothiazol-2-sulfenamide, N-ethyl-Nt- Butylbenzothiazol-2-sulfenamide, Nn-propyl-Nt-butylbenzothiazol-2-sulfenamide, Nn-butyl-Nt-butylbenzothiazo -L-2-sulfenamide, N-methyl-N-isoamylbenzothiazol-2-sulfenamide, N-ethyl-N-isoamylbenzothiazol-2-sulfenamide, Nn -Propyl-N-isoamylbenzothiazol-2-sulfenamide, Nn-butyl-N-isoamylbenzothiazol-2-sulfenamide, N-methyl-N-tert-amylbenzothia Sol-2 Sulfenamide, N-ethyl-N-tert-amylbenzothiazol-2-sulfenamide, Nn-propyl-N-tert-amylbenzothiazol-2-sulfenamide, N- n-butyl-N-tert-amylbenzothiazol-2-sulfenamide, N-methyl-N-tert-heptylbenzothiazol-2-sulfenamide, N-ethyl-N-tert- Heptylbenzothiazol-2-sulfenamide, Nn-propyl-N-tert-heptylbenzothiazol-2-sulfenamide, Nn-butyl-N-tert-heptylbenzothiazo -L-2-sulfenamide and the like. These compounds can be used alone or in admixture of two or more (referred to herein simply as “at least one”).
Preferably, from the viewpoint of further adhesion performance, N-methyl-Nt-butylbenzothiazol-2-sulfenamide, N-ethyl-Nt-butylbenzothiazol-2-sulfenamide Phenamide and Nn-propyl-Nt-butylbenzothiazol-2-sulfenamide are preferred.
Among these, N-methyl-Nt-butylbenzothiazol-2-sulfenamide, N-ethyl-Nt-butyl are particularly preferred in that they have the longest scorch time and excellent adhesion performance. It is desirable to use benzothiazol-2-sulfenamide or Nn-propyl-Nt-butylbenzothiazol-2-sulfenamide.
These compounds may be used alone or in combination. Also, general-purpose vulcanization accelerators such as N-tert-butyl-2-benzothiazol sulfenamide (TBBS), N-cyclohexyl-2-benzothiazol sulfenamide (CBS), dibenzothiazolyl disulfide (MBTS), etc. It is also possible to use in combination.

The following method can be mentioned as a preferable manufacturing method of the sulfenamide compound represented by the general formula (I) of the present invention.
That is, N-chloroamine and bis (benzothiazol-2-yl) disulfide prepared in advance by the reaction of the corresponding amine and sodium hypochlorite 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 raw material amine used in excess, tertiary amine such as triethylamine, alkali hydroxide, alkali carbonate, alkali bicarbonate, sodium alkoxide 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 the case of N-ethyl-Nt-butylbenzothiazol-2-sulfenamide, 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 under reflux for 2 hours. After cooling, neutralize with sodium hydroxide, filter, wash with water, concentrate under reduced pressure, and recrystallize to give the desired N-ethyl-Nt-butylbenzothiazol-2-sulfenamide (white Solid) can be obtained.

The content of these sulfenamide-based vulcanization accelerators is 0.1 to 10 parts by weight, preferably 0.5 to 5.0 parts by weight, and more preferably 0.8 parts per 100 parts by weight of the rubber component. The amount is desirably 8 to 2.5 parts by mass.
When the content of the vulcanization accelerator is less than 0.1 parts by mass, the vulcanization is not sufficiently performed. On the other hand, when the content exceeds 10 parts by mass, bloom is a problem, which is not preferable.

In addition to the rubber component, sulfur and vulcanization accelerator, the rubber composition used for the belt layer of the present invention can contain a filler usually used in the rubber composition used for the belt layer. An inorganic filler such as carbon black can be contained.
The content of these inorganic fillers is preferably 30 to 150 parts by mass, more preferably 40 to 100 parts by mass, and particularly preferably 40 to 65 parts by mass with respect to 100 parts by mass of the rubber component. It is.

There is no restriction | limiting in particular as carbon black to be used, It can select and use from what is conventionally used as a rubber reinforcement filler of a belt layer. Examples of carbon black include GPF, FEF, SRF, HAF, ISAF, and SAF. Carbon black having a nitrogen adsorption specific surface area (N ₂ SA) of 30 to 150 m ² / g and a dibutyl phthalate (DBP) oil absorption of 70 to 140 L / 100 g is preferable. By using carbon black, the effect of improving various physical properties is increased.

Furthermore, the rubber composition used for the coating rubber covering the steel cord of the belt layer 6 of the present invention may contain cobalt (single) and / or a compound containing cobalt from the viewpoint of improving the initial adhesion performance. preferable.
Examples of the cobalt-containing compound that can be used include at least one of a cobalt salt of an organic acid and a cobalt salt of an inorganic acid, such as cobalt chloride, cobalt sulfate, cobalt nitrate, cobalt phosphate, and cobalt chromate.
Preferably, it is desirable to use a cobalt salt of an organic acid from the viewpoint of further improving the initial adhesion performance.
Examples of the organic acid cobalt salt that can be used include at least one of cobalt naphthenate, cobalt stearate, cobalt neodecanoate, cobalt rosinate, cobalt versatate, cobalt tall oil, and the like. The organic acid cobalt may be a complex salt in which a part of the organic acid is replaced with boric acid. Specifically, a commercial name “manobond” manufactured by OMG Co., Ltd. may be used. In addition, in the steel (metal material) / rubber adhesion reaction, if cobalt is contained, the adhesion performance is improved even if it is not a cobalt salt such as a fatty acid.
The (total) content of these cobalt and / or cobalt-containing compounds is 0.03 to 3 parts by weight, preferably 0.03 to 1 part by weight, based on 100 parts by weight of the rubber component, as the amount of cobalt. More preferably, the content is 0.05 to 0.7 parts by mass.
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 reduced, which is not preferable.

The rubber composition used for the coating rubber for coating the steel cord of the belt layer 6 of the present invention has a rubber component consisting of isoprene rubber and transpolybutadiene, and N, It is desirable to contain N′-diphenylmethane bismaleimide.
The total weight part of the weight of the N, N′-diphenylmethane bismaleimide and the weight of the trans polybutadiene is 10 or less, and the weight of the trans polybutadiene is 25% or more and 95% or less of the total weight of the two. More preferably, the total weight part of the weight of the N, N′-diphenylmethane bismaleimide and the weight of the trans polybutadiene is 6 or less, and the weight of the trans polybutadiene is 25% or more of the total weight of the two, 95 %, Particularly preferably, the total weight part of the weight of the N, N′-diphenylmethane bismaleimide and the weight of the transpolybutadiene is 6 or less, and the weight of the transpolybutadiene is 25% of the total weight of the two. % Or more and 75% or less is particularly desirable.
The content of N, N′-diphenylmethane bismaleimide is preferably 0.1 to 4 parts by mass with respect to 100 parts by mass of the rubber component made of isoprene rubber and transpolybutadiene.
Further, the coating rubber has a tensile stress at 100% elongation of 3.5 MPa or more after vulcanization, and a tan δ of 0.200 or less when immediately applied under the condition of 2% strain at 25 ° C. It is preferable.
The trans polybutadiene preferably has a trans bond content of 82 to 98 mol% and a weight average molecular weight of 30,000 to 200,000.

In addition to the rubber component, sulfur, vulcanization accelerator, cobalt compound, etc., the rubber composition used for the coating rubber for coating the steel cord of the belt layer 6 of the present invention is a compound usually used in a tire belt layer. The agent can be used within a range that does not impair the effects of the present invention. For example, inorganic fillers such as silica other than the carbon black, softeners, anti-aging agents, and the like can be appropriately contained depending on the tire application.

In the present invention, a rubber composition for coating rubber that covers the steel cord of the belt layer 6 can be prepared by kneading the above-described components with, for example, a Banbury mixer, a kneader, etc., and tires such as passenger cars, trucks, and buses can be prepared. As a coating rubber for covering the steel cord of the belt layer 6, it can be suitably used for direct vulcanization adhesion with the steel cord.
The tire of the present invention is manufactured by a usual method. A rubber member that forms a belt layer is molded using the rubber composition having the above-described structure coated with the steel cord, and other tire members are pasted and molded on a tire molding machine by a normal method, thereby producing a raw tire. Is formed. The green tire is heated and pressurized in a vulcanizer to obtain the desired tire.

In the tire of the present invention configured as described above, it can be suitably applied to automobile and truck / bus tires that require particularly high strength, in response to demands for higher loads, higher speed, and higher life. Becomes a satisfactory tire, and is excellent in durability and crack resistance between the steel cord and the coating rubber in the belt layer and excellent in durability.
In addition, by using a rubber composition further containing cobalt (a simple substance) and / or a compound containing cobalt, it is further excellent in adhesion durability and crack resistance with a steel cord used for a belt layer of a tire, A tire having excellent durability can be obtained.
Further, as a rubber composition used for the coating rubber for covering the steel cord of the belt layer, the rubber component is made of isoprene rubber and transpolybutadiene and further containing N, N′-diphenylmethane bismaleimide. A tire, for example, a belt layer having a steel cord layer group embedded with four or more coating rubbers, and a tire for a large vehicle including at least a pair of crossing layers among the steel cord layer group, further for a large vehicle A large vehicle tire having excellent adhesion durability and crack resistance with a steel cord used for the belt layer of the tire and excellent durability can be obtained.

Next, the vulcanization accelerator used in the coating rubber for coating the steel cord of the belt layer of the present invention will be described in more detail based on the production examples of the vulcanization accelerator and the tire examples and comparative examples of the present invention. However, the present invention is not limited to these production examples and examples.
Further, the octanol / water partition coefficient (log P) of the obtained vulcanization accelerators (1 to 4) was measured by a high performance liquid chromatography method according to JIS Z 7260-117 (2006). A high performance liquid chromatography manufactured by Shimadzu Corporation was used.

[Production Example 1: Synthesis of N-ethyl-Nt-butylbenzothiazol-2-sulfenamide]
To 16.4 g (0.162 mol) of Nt-butylethylamine, 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-butylethylamine (24.3 g, 0.240 mol) 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 recrystallized to obtain the desired N-ethyl-Nt-butylbenzothiazol. -2-Sulfenamide was obtained as a white solid (melting point: 60 to 61 ° C.) of 41.9 g (yield: 66%).
The spectrum data of the obtained N-ethyl-Nt-butylbenzothiazol-2-sulfenamide 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.
The N-ethyl-Nt-butylbenzothiazol-2-sulfenamide had an octanol / water partition coefficient (log P) of 4.9.

[Production Example 2: Synthesis of N-methyl-Nt-butylbenzothiazol-2-sulfenamide]
N-methyl-Nt-butylbenzothiazol-2 was prepared in the same manner as in Example 1 except that 14.1 g (0.162 mol) of Nt-butylmethylamine was used instead of Nt-butylethylamine. -Obtained 46.8 g (82% yield) of sulfenamide as a white solid (melting point 56-58 ° C.).
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).
Further, the octanol / water partition coefficient (log P) of this N-methyl-Nt-butylbenzothiazol-2-sulfenamide was 4.5.

[Production Example 3: Synthesis of Nn-propyl-Nt-butylbenzothiazol-2-sulfenamide]
The same procedure as in Example 1 was carried out using 18.7 g (0.162 mol) of Nn-propyl-t-butylamine instead of Nt-butylethylamine, and Nn-propyl-Nt-butylbenzothia Sol-2-sulfenamide was obtained as a white solid (melting point 50-52 ° C.).
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.
The Nn-propyl-Nt-butylbenzothiazol-2-sulfenamide had an octanol / water partition coefficient (log P) of 5.3.

[Production Example 4: Synthesis of Nn-butyl-Nt-butylbenzothiazol-2-sulfenamide]
The same procedure as in Example 1 was carried out using 20.9 g (0.162 mol) of Nt-butyl-n-butylamine instead of Nt-butylethylamine, and Nn-butyl-Nt-butylbenzothia Sol-2-sulfenamide was obtained as 42.4 g (yield 60%) of a white solid (melting point 55-56 ° C.).
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 .
The Nn-butyl-Nt-butylbenzothiazol-2-sulfenamide had an octanol / water partition coefficient (log P) of 5.8.

[Examples 1 to 12 and Comparative Examples 1 to 8]
Using a 2200 ml Banbury mixer, the rubber component, sulfur, the vulcanization accelerator obtained in the above production example, the organic acid cobalt salt, and other compounding agents were kneaded and mixed according to the formulation shown in Tables 1 to 3 below. Thus, an unvulcanized rubber composition was prepared. Using each rubber composition obtained, the following evaluation methods were used to evaluate heat resistance adhesion and tire durability as well as adhesion durability and crack durability.
These results are shown in Tables 1 to 3 below.

[Adhesion performance evaluation method]
Three steel cords (outer diameter 0.5 mm x length 300 mm) plated with brass (Cu: 63 wt%, Zu: 37 wt%) are arranged in parallel at 10 mm intervals, and this steel cord is coated with each rubber composition from both the upper and lower sides. This was vulcanized at 160 ° C. for 20 minutes to prepare a sample.
Regarding the adhesion of each sample obtained, the steel cord was pulled out from each sample in accordance with ASTM-D-2229, and the rubber coating state was visually observed and displayed at 0 to 100%. It was used as an index. For heat-resistant adhesion, each ampoule is left in a gear oven at 100 ° C for 15 to 30 days, then the steel cord is pulled out by the above test method, and the rubber coating state is visually observed and displayed in 0 to 100%. And used as an index for each thermal adhesiveness. It shows that it is excellent in heat-resistant adhesiveness, so that a numerical value is large.

[Tire evaluation: Evaluation method of adhesion durability]
Each rubber composition obtained above was coated with a steel cord (1 × 5 structure, strand 0.25 mm) to form a belt layer, and a pneumatic rasil tire of size TBR11R22.5 provided with the belt layer was usually used. Prototype by the method.
Each prototype tire obtained was evaluated for indoor drums. Specifically, after running at normal internal pressure, normal load, constant speed, and step load, the steel cord was pulled out of the steel cord cut sample of the crossing layer, and the rubber coating state was visually observed. And was displayed in a range of 0 to 100%, and Comparative Example 1 was evaluated with reference (index display: 100). It shows that it is excellent in adhesive durability, so that a numerical value is large.

[Tire evaluation: Crack durability evaluation method]
Each rubber composition obtained above was coated with a steel cord (1 × 6 structure, elemental wire 0.25 mm) to form a belt layer, and a pneumatic rasil tire of size TBR11R22.5 equipped with the belt layer was usually used. Prototype by the method.
Each prototype tire obtained was evaluated for indoor drums, specifically, normal internal pressure, normal load, constant speed, step load running, and crack length developed from the end of the belt after the test. It was evaluated as (index indication: 100). It shows that it is excellent in crack durability, so that a numerical value is large.

As is apparent from the results of Tables 1 to 3, the tires of Examples 1 to 12 that fall within the scope of the present invention are more resistant to heat than the tires of Comparative Examples 1 to 8 that fall outside the scope of the present invention. It was found that an excellent rubber composition could be obtained, and that this was used as a coating rubber for coating the steel cord of the tire belt layer was excellent in durability (adhesion durability and crack durability).

In the tire of the present invention, the coating rubber covering the steel cord of the belt layer is suitable for passenger cars, trucks, buses and the like by using a suitable rubber composition that is directly vulcanized and bonded to the steel cord. .

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Carcass 5 Bead core 6 Belt layer

Claims

A tire having a steel cord and a belt layer made of a coating rubber covering the steel cord, wherein the coating rubber covering the steel cord of the belt layer includes a rubber component, sulfur, and the following general formula (I): A tire comprising a rubber composition containing a sulfenamide-based vulcanization accelerator represented.
2. The rubber composition according to claim 1, wherein the rubber composition contains 0.1 to 10 parts by mass of the sulfenamide vulcanization accelerator represented by the general formula (I) with respect to 100 parts by mass of the rubber component. tire.
The tire according to claim 1, wherein the rubber composition contains 0.3 to 10 parts by mass of sulfur with respect to 100 parts by mass of the rubber component.
The rubber composition comprises 0.3 to 10 parts by mass of sulfur and 0.1 to 10 parts by mass of a sulfenamide vulcanization accelerator represented by the above general formula (I) with respect to 100 parts by mass of the rubber component. The tire according to claim 1, comprising:
The tire according to claim 1, wherein R 1 in the general formula (I) is a tert-alkyl group and n = 0.
2. In the general formula (I), R 1 is a tert-butyl group, R 2 is a linear alkyl group having 1 to 6 carbon atoms, and R 3 to R 6 are hydrogen atoms. Tire described in.
In the general formula (I), R 1 is a tert-butyl group, n = 0, R 2 is a linear alkyl group having 1 to 6 carbon atoms, and R 3 to R 6 are hydrogen atoms. The tire according to claim 1, which is an atom.
In the general formula (I), R 1 is a tert-butyl group, n = 0, R 2 is a methyl group, an ethyl group, or an n-propyl group, and R 3 to R 6 are hydrogen atoms. The tire according to claim 1.
The tire according to any one of claims 1 to 8, wherein the rubber composition further contains cobalt and / or a compound containing cobalt.
The tire according to claim 9, wherein the content of cobalt and / or a compound containing cobalt is 0.03 to 3 parts by mass with respect to 100 parts by mass of the rubber component as the amount of cobalt.
The tire according to claim 9 or 10, wherein the compound containing cobalt is a cobalt salt of an organic acid.
The tire according to any one of claims 1 to 11, wherein the rubber component of the rubber composition contains at least one of natural rubber and polyisoprene rubber.
The tire according to any one of claims 1 to 11, wherein the rubber component of the rubber composition is 50% by mass or more of natural rubber and the balance is synthetic rubber.
The tire according to any one of claims 1 to 11, wherein the rubber component of the rubber composition is made of isoprene rubber and transpolybutadiene and contains N, N'-diphenylmethane bismaleimide.
The tire according to claim 14, wherein the belt layer has a steel cord layer group buried with four or more coating rubbers, and includes at least a pair of crossing layers in the steel cord layer group.
A total weight part of the weight of the N, N'-diphenylmethane bismaleimide and the weight of the trans polybutadiene is 10 or less, and the weight of the trans polybutadiene is 25% or more and 95% or less of the total weight of the two. The tire according to 14 or 15.
A total weight part of the weight of the N, N'-diphenylmethane bismaleimide and the weight of the trans polybutadiene is 6 or less, and the weight of the trans polybutadiene is 25% or more and 95% or less of the total weight of the two. The tire according to 14 or 15.
A total weight part of the weight of the N, N'-diphenylmethane bismaleimide and the weight of the trans polybutadiene is 6 or less, and the weight of the trans polybutadiene is 25% or more and 75% or less of the total weight of the two. The tire according to 14 or 15.
The tire according to any one of claims 14 to 18, wherein a content of the N, N'-diphenylmethane bismaleimide is 0.1 to 4 parts by mass with respect to 100 parts by mass of the rubber component.
The tire according to any one of claims 14 to 19, wherein the tire is a tire for a large vehicle.
The coating rubber has a tensile stress at 100% elongation of 3.5 MPa or more after vulcanization and a tan δ of 0.200 or less when immediately applied under the condition of 2% strain at 25 ° C. The tire according to any one of 14 to 19.
The tire according to any one of claims 14 to 21, wherein the trans polybutadiene has a trans bond content of 82 to 98 mol% and a weight average molecular weight of 30,000 to 200,000.