JPH0565370A - Tire - Google Patents

Abstract

PURPOSE:To find out the kinds of adhesion promoter which can improve the initial adhesive power and the moisture- and heat-resistant adhesiveness and can shorten the vulcanizing time in the process for manufacturing tires and a specified plating composition corresponding thereto, and to provide a tire made by using a rubber composition consisting of a combination of the adhesion promoters with a desirable crosslinking system. CONSTITUTION:A tire is formed in such a manner that steel cords plated with a composition having a copper/zinc ratio of (60:40) to (65:35) are covered with rubber composition made by mixing 100 pts.wt. of at least one rubber component selected from among natural rubber, polyisoprene rubber, polybutadiene rubber and a styrene/butadiene copolymer rubber, 0.1-0.6 pt.wt., in terms of cobalt metal, of at least one cobalt acetylacetonate, and 3-8 pts.wt. sulfur.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire, such as a steel belt radial tire, capable of shortening the vulcanization time in the manufacturing process.

[0002]

2. Description of the Related Art Generally, in a tire reinforced with a steel cord, the heat generated during running and, in some cases, the heat under high humidity cause a decrease in the adhesive force between the rubber and the steel cord, resulting in a tire failure. Cause of. Further, in recent years, since vulcanization in a short time is important from the viewpoint of streamlining the manufacturing process and saving energy, the adhesion promoter used for bonding the steel cord and the rubber is not only heat resistant and wet heat resistant, There is a further demand to significantly increase the initial adhesive strength.

Conventionally, a cobalt oxyketone complex has been proposed in JP-A-1-118549 and JP-A-1-1558058 as a promoter having a high initial adhesiveness and suitable for shortening the vulcanization time. The incorporation of this cobalt oxyketone complex is effective in improving initial adhesion and heat resistant adhesion. Further, as a method for achieving both initial adhesion, heat resistant adhesion, and wet heat resistant adhesion, it is recommended to use a cobalt oxyketone complex and a bismaleimide compound in combination as described in JP-A-1-118547.

Further, conventionally, in a heavy-duty steel radial tire, there are two methods for shortening the vulcanization time: increasing the vulcanization temperature or increasing the vulcanization speed of the tire.

[0005]

However, in such a conventional tire, when the vulcanization time is shortened by increasing the vulcanization temperature, the tire durability is lowered. Occurs. Further, if the vulcanization speed is increased and the vulcanization speed is increased to shorten the vulcanization, there is a problem in the adhesion between the rubber for the belt and the steel cord.

[0006] Further, as a means for achieving both the shortening of the vulcanization time and the adhesiveness under various conditions such as the above-mentioned initial adhesion at the time of manufacturing, heat resistant adhesion, and moisture heat resistant adhesion, the above-mentioned JP-A-1-11.
Although those disclosed in Japanese Patent No. 8547 and the like are disclosed, this is not sufficient. In particular, in order to apply it to a large tire in which the vulcanization temperature of the belt end rubber is lower than that of a small tire, it is necessary to develop a new method for balancing the initial adhesion and the wet heat resistance.

The present invention has been made against such a background of the prior art, and further improves the initial adhesive strength and the resistance to moist-heat adhesion in the tire manufacturing process, and makes it possible to shorten the vulcanization time. The first object is to clarify the type of promoter and the specific plating composition of the corresponding steel cord, and the second object is to provide a tire using a rubber composition comprising a combination of these and a preferred Kabashi system. To aim.

[0008]

In order to increase the vulcanization rate of large tires and shorten the vulcanization time of the large tire, the inventor of the present invention has found that plating is one of the factors governing the adhesive force between rubber and cord in the conventional adhesion promoter technology. Focusing on the interaction with the composition,
We proceeded with the study and conducted various studies to reach this conclusion.

The present invention relates to 100 parts by weight of at least one rubber component selected from the group consisting of natural rubber, polyisoprene rubber, polybutadiene rubber and styrene / butadiene copolymer rubber, and at least one of acetylacetone cobalts. 0.1 to 0 with cobalt metal as seed.
The rubber composition containing 6 parts by weight of sulfur and 3 to 8 parts by weight of sulfur makes the copper / zinc ratio of the plating composition of the cord 60/4.
Characterized by coating a steel cord having 0-65 / 35.

Here, the acetylacetone cobalts mean the following general formula, chemical formula and general formula

[0011]

[Chemical 1]

Acetylacetone-cobalt cobalt,
(In the formula, Me is a methyl group.)

[0013]

[Chemical 2]

Acetylacetone secondary cobalt etc. represented by

[0015]

[Chemical 3]

Aminoacetylacetonecobalt represented by the formula (wherein Me is a methyl group, φ ₁ and φ ₂ are respectively represented by the following general formula,

[0017]

[Chemical 4]

[0018]

[Chemical 5]

In the formula, Y ₁ to Y ₁₀ are the same or different, and a hydrogen atom, a C _{1 to} C ₁₀ alkyl group, a C _{5 to} C ₁₂ cycloalkyl group, a C _{4 to} C ₁₄ aryl group, C ₆ -C ₁₄ aryl-C ₁ -C ₄ alkyl group, C ₁
To C ₁₀ alkoxy group, C _{5 to} C ₁₂ cycloalkoxy group,
C ₆ -C ₁₄ aryloxy group, C ₄ -C ₁₄ aryl-C
_{It is one of those represented by 1 to} C ₄ alkoxy groups, halogen atoms, or C _{2 to} C ₁₆ (which represents a hydrocarbon group) having one or more double bonds.

In the rubber composition of the present invention, a vulcanization accelerator is used in addition to the rubber selected from the above rubber group, acetylacetone cobalts and sulfur. Various kinds of vulcanization accelerators are used, and among them, sulfenamide-based ones are preferably used. Among the sulfenamide-based accelerators,
Accelerator CZ (N-cyclohexyl-2-benzothiazylsulfenamide), which has a relatively high vulcanization rate, and accelerator NS
(N-tert-butyl-2-benzothiozolylsulfenamide), accelerator NOBS (N-oxydiethylene-2-benzothiazole), accelerator DS (2- (chimorpholinodithio) benzothiazole), accelerator DB
M (2- (2,4-dinitrophenyl) mercapto-benzothiazole), accelerator Noxera-64 (NN'-diethylthiocarbamoyl-2-benzothiazole),
It is preferable because the vulcanization rate and the adhesion rate of the steel cord can be easily balanced. If necessary, these sulfenamide accelerators and other accelerators, for example, thiazole accelerators such as DM (dibenzothiazyl disulfide), or accelerator TT (tetramethylthiuram disulfide) or TS
When used in combination with a thiuram-based accelerator such as (tetramethylthiuram monosulfide), the adhesion speed can be adjusted.

When the accelerator DZ (N, N'-dicyclohexyl-2-benzothiazolylsulfenamide) having a slow vulcanization rate is used, the vulcanization rate is adjusted by using it together with the accelerator NS or the accelerator DM. By increasing the speed, it is possible to achieve both shortening of vulcanization and adhesion. In addition to the rubber, acetylacetone cobalts, vulcanization accelerator, and sulfur, the rubber composition of the present invention may contain various compounding agents depending on the purpose. Other compounding agents include carbon black, silica,
Reinforcing agents such as calcium carbonate, fillers, softeners such as aroma oil, vulcanization accelerating aids, antioxidants, and other compounding agents normally used in the rubber industry can be added in the usual compounding range, if necessary. Can be compounded within.

[0022]

In the present invention, 0.1 to 0.6 parts by weight is added as the metal weight of cobalt to 100 parts by weight of the rubber component. If the amount is less than 0.1 parts by weight, the effect is too small, and
If it exceeds 0.6 parts by weight, the physical properties of the rubber after aging deteriorate, which is not preferable. Also, regarding sulfur, if the amount is less than 3 parts by weight, the bond of copper-sulfur-rubber is less likely to be generated, resulting in poor adhesion, and if the amount exceeds 8 parts by weight, the rubber physical properties after aging are deteriorated, which is not preferable.

Further, it is also very important for the plating of steel cords. If the ratio of copper to zinc is less than 60, the adhesion with rubber will be delayed and the adhesion will be problematic. When there is a lot of water, for example, a problem occurs in adhesion in the summer and the like, so it is necessary to use a steel cord in which the copper / zinc ratio is regulated to 65/35 to 60/40. Such a rubber composition of the present invention is suitable for a coating rubber composition such as a steel belt, a steel breaker, a steel carcass ply, a wire chafer, a wire flipper and a bead wire of a tire using a steel cord having the above-mentioned plating composition. Is.

[0024]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples. Examples 1 to 10, Comparative Examples 1 to 3 Natural rubber (abbreviated as NR), polyisoprene rubber (I
R), polybutadiene rubber (abbreviated as BR), and styrene-butadiene copolymer rubber (abbreviated as SBR). At least one rubber component selected from the group consisting of, for example, Table 1 in Example 1. As shown, 80 parts by weight of natural rubber, 20 parts by weight of polybutadiene rubber, 60 parts by weight of HAF carbon black (abbreviated as HAF), 8 parts by weight of zinc white (abbreviated as ZnO), 1 part by weight of 6c of aged rubber,
As cobalt metal weight of cobalt species (AAC-Co)
0.2 parts by weight, 1.3 parts by weight of accelerator NS as a vulcanization accelerator,
A rubber composition was prepared by kneading 6.0 parts by weight of sulfur with a Banbury mixer. On the other hand, the plating ratio Cu / Zn of the steel cord prepared in Example 1 was 65/35. The obtained rubber composition was evaluated for vulcanization rate, initial adhesion to steel cord, and wet heat resistance. The results obtained are also shown in the table.

Also in Examples 2 to 10 and Comparative Examples 1 to 3, the compounding agents shown in Table 1 were used, and adjustment was carried out in the same manner as in Example 1. Also, the plating ratio Cu / Zn of the steel cord was prepared in the same manner as in Example 1.
Then, with respect to the obtained rubber composition, the vulcanization rate, the initial adhesiveness, and the wet heat resistance were evaluated in the same manner as in Example 1 and are also shown in Table 1.

The measurement of the plating ratio and the evaluation of the vulcanization rate, the initial adhesiveness and the wet heat resistance were carried out as follows. Measurement of plating ratio It was carried out by a calibration curve method using a standard solution for atomic absorption by a PW1404 fluorescent X-ray tester manufactured by Philips.

The vulcanization rate vulcanization rate t0.9 the time required to obtain 90% of the maximum torque value of the vulcanization torque curve measured at a temperature 155 ° C. ± 1 ° C. using manufactured by Japan Synthetic Rubber Co., Ltd. curelastometer is there. Initial adhesion surface Brass plated steel cord 1 × 3 × 0.20mm + 6
After vulcanizing a steel cord-rubber composite in which 0.36 mm is embedded in unvulcanized rubber for 145 ° C for 16 minutes, a peel test between the steel cord and the embedded rubber layer is performed according to JIS K 6301 peel test. The adhesiveness was evaluated by the amount of rubber attached on the top. The state in which the cord was covered with rubber, that is, the state in which the rubber was attached was visually measured in percentage, and evaluated by the 5-point method described later.

Moisture and Heat Resistance Adhesion The same steel cord-rubber composite as that used in the initial adhesion test was allowed to stand in a thermo-hygrostat at 80 ° C. × 95% humidity for 7 days, and then the rubber was adhered in the same manner as the initial adhesion. Was evaluated by the 5-point method. In Table 1, 5 is with rubber 100-80%, 4 is with rubber 80
-60%, 3 with rubber 60-40%, 2 with rubber 40-20%, 1
Is less than 20% with rubber.

The abbreviations of compounding agents in Table 1 indicate the abbreviations described above and the following compounds. Co naphthenate is cobalt naphthenate, AAC-Co is acetylacetone cobalt, and 3A-Co is aminoacetylacetone cobalt.

[0030]

[Table 1]

As is clear from Examples 1 to 7 in Table 1,
With the rubber composition having a bridge system in which one of acetylacetone cobalts is blended and sulfur and an accelerator NS are suitably blended, the cord plating composition has a copper / zinc ratio of 60/4.
When the steel cord of 0 to 65/35 is coated, the vulcanization speed can be improved, the vulcanization time can be shortened, and the initial adhesion and wet heat resistance can be greatly improved.

Further, as is clear from Examples 8 to 10 in Table 1, by further suitably combining the Kabashi system in the above, the vulcanization time can be shortened similarly to the above, and the initial adhesion and A tire was molded in the same manner as usual using the rubber compositions and steel cords of the above-mentioned Examples 1 to 10 capable of significantly improving the resistance to moist heat, and the result of vulcanization was the initial adhesive strength and the resistance to moist heat in the tire manufacturing process. Adhesiveness could be greatly improved and vulcanization time could be shortened significantly. Also, the durability of the tire was sufficient.

[0033]

As described above, according to the present invention,
By coating a steel cord having a specific plating composition with a rubber composition in which a specific amount of acetylacetone cobalt is blended as an adhesion promoter, it is possible to improve the initial adhesive strength and wet heat resistance in the tire manufacturing process and to obtain a suitable balance. The vulcanization time can be shortened and the vulcanization time can be shortened, and the vulcanization time can be shortened similarly to the above by appropriately combining the crosslinking system, and the initial adhesiveness and wet heat resistance can be significantly improved. ..

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Claims (1)

[Claims] 1. At least one of acetylacetone cobalts is added to 100 parts by weight of at least one rubber component selected from the group consisting of natural rubber, polyisoprene rubber, polybutadiene rubber and styrene-butadiene copolymer rubber. With a rubber composition containing 0.1 to 0.6 parts by weight of cobalt metal and 3 to 8 parts by weight of sulfur, the copper / zinc ratio of the plating composition of the cord is 60/40 to 65 /.
A tire characterized by coating a steel cord having 35.