JPS61238501A - Pneumatic tire improved in durability - Google Patents

Abstract

PURPOSE:To improve durability without entailing any damage to abrasion resistance and gripping performance, by constituting a tread with the specified compounded rubber of styrene-butadiene copolymerized rubber or its blended rubber, the specified vulcanization accelerator, a vulcanizing agent and a bismuthamide compound. CONSTITUTION:A rubber composition for a tread is constituted of compounding 0.3-3wt.p. of a vulcanization accelerator of dibenzothiazyldisulfite or the like, 0.3-3wt.p. of sulfur and 0.1-1.5wt.p. of a bismuthamid compound expressed in a chemical equation I (see illustration) to blended rubber of 100wt.p. composed of styrene-butadiene copolymerized rubber or more than 30wt.p. of this rubber and 70wt.p. of rubber selected out of natural rubber or the like. And, the sulfur and the bismuthamid compound are set to 1/1 to 3/1 while the vulcanizing agent and this bismuthamid compound are set to 1/1 to 3/1, respectively. With this constitution, durability is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pneumatic tire, and more particularly to a high maneuverability pneumatic tire with improved mechanical durability.

[Conventional technology]

Recently, with the improvement of automobile performance and the development of expressway networks,
Demand for pneumatic tires with high maneuverability is increasing, with grip performance being an especially important required characteristic, typified by acceleration performance and braking performance. Therefore, tires with high levels of these properties can run faster and more accurately.

Conventionally, in order to obtain high grip performance, styrene-butadiene copolymer rubber with a high styrene content (rubber with a high glass transition temperature) was selected as the polymer in the tread rubber composition, or highly filled with oil and carbon blank. It was necessary to select a compounding system with a high hysteresis loss, and it was necessary to increase the hysteresis loss of the tread rubber composition.

For this reason, when tires run at high speeds, they generate heat due to hysteresis loss, and as the tire temperature rises during high-speed running, blow occurs in the tread rubber, causing a loss of rubber elasticity and grip performance. The so-called plow-out (bl
This method has the disadvantage of causing the phenomenon of ``owout''.

[Problems to be Solved by the Invention] As described above, it is difficult for conventional tread rubber compositions to respond to improvements in the performance of automobiles, and in particular, it is difficult to achieve high durability without compromising grip performance and wear resistance. I couldn't do it. The present invention aims to solve this problem.

[Means to solve problems]

In addition to sulfur, which is commonly used as a vulcanizing agent, the present invention uses conventional peroxide crosslinking aids such as Sihypalon and lorosulfonated polyethylene, and polyisoprene rubber as a base for long-term vulcanization or high-temperature vulcanization ("polymer vulcanization"). 'Friends' July 1975 P327. August 1977 P484
．． October 1979 P590. October 1981 P59
2 to P593. September 1982 P533) shows that the bismaleimide compound is effective, and that the blowout performance is improved by the ratio of sulfur to the bismaleimide compound and the ratio of the vulcanization accelerator to the bismaleimide compound. This is, of course, based on the discovery that the mechanical properties required for tires vary greatly.

That is, the present invention provides at least 30 parts by weight of styrene-butadiene copolymer rubber or styrene-butadiene copolymer rubber and at least one member selected from the group consisting of natural rubber, synthetic polyisoprene rubber, polybutadiene rubber, butyl rubber, and halogenated butyl rubber. Dibenzothiazyl disulfide, N-cyclohexyl-2-benzotheazylsulfenamide, N-cyclohexyl-2-benzotheazylsulfenamide,
-Oxydiethylene-2-benzothiazylsulfenamide, N,N-dicyclohexyl-2-benzothiazylsulfene 7<)', N-tθrt-butyl-2-penzteazilsulfenamide, tetramethyl At least one compound selected from the group consisting of thiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetramethylthiuram monosulfide, and tetrabutylthiuram monosulfide 0.
3 to 3 parts by weight, 0.3 to 3 parts by weight of sulfur as a vulcanizing agent, and the following general formula (1), (&';L, RH phenylene group, naphthylene group, -(O
Hz) n-group, n represents an integer of 2 to 6) A rubber composition comprising 01 to 1.5 parts by weight of a bismaleimide compound, the weight ratio of the sulfur/bismaleimide compound being: A pneumatic tire with improved durability characterized in that a rubber composition having a vulcanization accelerator/bismaleimide compound weight ratio of 1/1 to 3/1 is used in the tread. It is related to the tire.

In the present invention, styrene-butadiene copolymer rubber is an essential component, but in order to obtain particularly high grip performance, the styrene content is 600 parts by weight, preferably 355 parts by weight. Polymerized rubber is preferred, and in this case, even if the high styrene-butadiene copolymer rubber is used alone, the rubber has a styrene content of 30 parts by weight or more and a styrene content of 30% by weight or less, preferably 255 parts by weight or less of styrene. - Butadiene copolymer rubber It may be a blended rubber containing 70 parts by weight or less. In addition, in the present invention, styrene-butadiene copolymer rubber 30
:J' It is possible to use one or more of natural rubber, synthetic polyimbrene rubber, polybutadiene rubber, butyl rubber, and halogenated butyl rubber in combination depending on the intended use.

In the present invention, dibenzotheazyl sulfide (DM), N-cyclohexyl-2-penzothiazyl sulfenamide (C2), N-O#cydiethylene-2-benzothiazyl sulfenamide (C2)" ( N0B
S), N,N-zinchlorohexyl-2-benzothiazylsulfenamide (DZ), N-tert-butyl-2-benzothiazylsulfenamide (N8), tetramethylthiuram disulfide (TMTD), tetraethylthiuram At least one vulcanization accelerator selected from the group consisting of disulfide (TETD), tetrabutylthiuram disulfide (Tl3TD), tetramethylthiuram monosulfide (TMTM), and tetrabutylthiuram monosulfide (TBTM) is used; It is preferable to use DM in combination with a sulfenamide accelerator and/or a thiuram accelerator.
．． It is 3 to 3 parts by weight. When the amount of compound 'M' is less than 0.3 parts by weight, there is no accelerating effect of the vulcanizing agent, and when it exceeds 3 parts by weight,
It is no longer a scale that can be expected to have much of an effect of increasing the amount, and the scorch time becomes short, which is not desirable.

In the present invention, sulfur and the general formula (1
) is used, and specific examples of this bismaleimide compound are tL, 'tT,
N'-m-phenylene bismaleimide, N, 14'
-1,5-naphthylene bismaleimide, N,11'-ethylene bismaleimide, N,N'-tetramethylene hismaleimide, N,N'-hexamethylene bismaleimide, and the like. The amount of sulfur to be blended is 0.3 to 3 parts by weight, preferably 0.3 to 25 parts by weight. If it is less than 0.3 parts by weight, the addition will not be effective, and if it exceeds 11 parts by weight, the rubber composition will be This is not preferable because the hardness becomes too high and the grip performance deteriorates. In addition, the blending amount i of the bismaleimide compound
; j: 11 to 1.5 parts by weight, 0.1 parts by weight] If the amount is less than 4 parts, the blowout property will not be improved, and if it exceeds 1.5 parts, unreacted bismaleimide will be released after vulcanization. As a result, the hardness and modulus of the rubber composition become too high during the middle to late stages of running, which also deteriorates the grip performance, which is undesirable.

In the present invention, the combination ratio of the above-mentioned vulcanization accelerator, sulfur, and bismaleimide compound is extremely important. That is, the weight ratio of vulcanization accelerator/bismaleimide compound is 1/1 to 3.
/1. If the amount of the vulcanization accelerator is less than the weight ratio of 1/1, sufficient crosslinking of the bismaleimide compound will not be generated, and the blowout performance will not be improved, which is undesirable.
If the value of the vulcanization accelerator is greater than 1, the scorch time becomes short and factory workability such as extrusion workability deteriorates, which is not preferable. The weight ratio of sulfur/bismaleimide compound is 1/1 to 3/1, preferably 1/1 to 2.5/1.
It is. If the weight ratio is less than 1/1, the wear resistance deteriorates, which is not preferable, and if the weight ratio is more than 3/1, the effect of the combination of the bismaleimide compound is lost, and the blowout performance is not improved, which is not preferable.

In addition to the above-mentioned vulcanizing agent and vulcanization accelerator, in the present invention,
Compounding agents commonly used in the rubber industry, such as reinforcing agents such as carbon black, process oils such as aroma oils, plasticizers, anti-aging agents, and vulcanization accelerators may be appropriately blended as required.

[Effects of the Invention] As detailed above, the pneumatic tire according to the present invention has the following effects:
Since the tread is made of the rubber composition having the above-mentioned structure, durability is significantly improved without impairing wear resistance or grip performance.

〔Example] The present invention will be explained in detail below using comparative examples and examples.

Examples 1 to 7, Comparative Examples 1 to 4 Various rubber compositions were prepared according to the formulation contents shown in Table 1, and the vulcanization ridge, blowout properties, and tire size 195/60 i (R14 The results are shown in Table 1.

The evaluation method is as follows.

(Blowout properties) Rubber is heated by dynamic compression using a Gutdrich flexmeter, and the temperature at which bubbles begin to form is evaluated.

(High-speed durability) Tires were first tested for 81 km on a drum under constant load conditions.
/ After running for 2 hours at a speed of H, let it cool and run it at 121
km/H for 30 minutes, then 8 minutes every 30 minutes.
The speed at which the tread blows out was evaluated by increasing the km/H speed, and expressed as an index with Comparative Example 1 set as 100. The higher the value, the better.

(Abrasion resistance) After driving the actual vehicle for 50,000 km, the remaining groove was measured and the abrasion resistance was evaluated. Comparative Example 1 was divided into 100 and expressed as an index. The value is as good as it gets.

(To) As is clear from Table 1, the pneumatic tires according to the present invention shown in Examples have significantly improved high-speed durability due to improved tread blowout properties.

Claims (1)

[Scope of Claims] Styrene-butadiene copolymer rubber or the styrene-butadiene copolymer rubber
100 parts by weight of blended rubber consisting of 30 parts by weight or more of butadiene copolymer rubber and 70 parts by weight or less of at least one rubber selected from the group consisting of natural rubber, synthetic polyisoprene rubber, polybutadiene rubber, butyl rubber, and halogenated butyl rubber. %, as a vulcanization accelerator, dibenzothiazyl disulfide, N-cyclohexyl-2
-benzothiazylsulfenamide, N-oxydiethylene-2-benzothiazylsulfenamide, N,N-
Dicyclohexyl-2-benzothiazylsulfenamide, N-tert-butyl-2-benzothiazylsulfenamide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetramethylthiuram mono sulfide,
0.3 to 5 parts by weight of at least one compound selected from the group consisting of tetrabutylthiuram monosulfide, 0.3 to 5 parts by weight of sulfur as a vulcanizing agent, and general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (Here, R is a phenylene group, a naphthylene group, -(CH_
2) A rubber composition containing 0.1 to 1.5 parts by weight of a bismaleimide compound represented by __n- group, where n is an integer of 2 to 6, and the weight ratio of sulfur/bismaleimide compound is 1/1 to 3/1, and the weight ratio of vulcanization accelerator/bismaleimide compound is 1/1 to 3/1. Mobility pneumatic tire. 2. The blending amount of sulfur is 0.5 to 2.5 parts by weight and sulfur/
The pneumatic tire according to claim 1, wherein the weight ratio of bismaleimide is 1/1 to 2.5/1. 3. The amount of bismaleimide compound is 0.25 to 1.2
parts by weight and the weight ratio of sulfur/bismaleimide compound is 1
．． The pneumatic tire according to claim 1, wherein the weight ratio of vulcanization accelerator/bismaleimide compound is 2/1 to 3/1 and 1.2/1 to 3/1.