JPH0598074A - Heavy-duty tire - Google Patents

Abstract

PURPOSE:To obtain the title tire excellent in durability to generated heat, abrasion resistance, etc., by arranging a rubber composition comprising a rubber composed mainly of a diene rubber, a specified reinforcing filler, a specified chemical substance, a softening agent, and zinc white in the tire tread. CONSTITUTION:The title tire is formed by arranging in the tire tread a rubber composition comprising 100 pts.wt. rubber composed mainly of a diene rubber, such as natural rubber or isoprene rubber, 40-70 pts.wt. reinforcing filler comprising a carbon black having a specified specific surface based on N2 adsorption and a specified dibutyl phthalate absorption or a blend of the carbon black with silica, at most 10 pts.wt. softening agent (e.g. an aromatic oil), 0.05-5 pts.wt. of at least one of chemical substances of formulas I, II and III [wherein A is an aromatic ring, a (substituted) hydantoin ring or a 0-18C (un)saturated linear hydrocarbon group; B is an aromatic group; X is hydroxy or amino; Y is pyridyl or hydrazino], and 5.5-15 pts.wt. zinc white.

Description

Detailed Description of the Invention

[0001]

[Industrial application] Heavy-duty tires using tread rubber with significantly improved heat resistance without lowering wear resistance and fracture resistance.

[0002]

2. Description of the Related Art A tire used under a high load is repeatedly subjected to a large strain amplitude in a rubber composition arranged in a tread portion, which causes a tire temperature to rise.
It significantly reduces tire life. In order to improve the heat generation durability of the tire, it is necessary to improve the heat generation resistance of the tire tread rubber composition and suppress an increase in tire temperature.

Conventionally, in heavy duty tires, in order to obtain the desired heat resistance, the type and amount of carbon black in the rubber composition should be increased by increasing the particle size of the carbon black or decreasing the compounding amount. It has been dealt with by changing it, but at the same time, this compromises the performance of both because it reduces the wear resistance of the tread rubber and the fracture resistance of the rubber such as cut resistance and chipping resistance. In this respect, the composition of the rubber composition had to be set.

Japanese Patent Application Laid-Open No. 60-23409 discloses a method for reducing heat generation by using styrene-butadiene rubber (SBR) whose molecular end is modified with a special compound, particularly for the purpose of tires for passenger cars. Has been done. Although these methods can be applied to solution-polymerized SBR, they are superior in high temperature fracture properties to other rubbers, especially natural rubber most widely used for heavy vehicle tires, and generally solution-polymerized SBR. It could not be applied to emulsion polymerization SBR at all.

The present applicant previously filed Japanese Patent Application No. 2-255309.
Provides a rubber composition for low fuel consumption tires containing a specific rubber heat generation improver. The present invention provides a tire equipped with a heavy load tread rubber, in which various requirements necessary for heavy load are clarified by utilizing the rubber heat improver.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to suppress the heat generation of a tire even when it is mounted on a heavy-duty tire without deteriorating the wear resistance and fracture resistance of the conventional tread rubber. It is to provide a heavy-duty tire equipped with a tread rubber capable of improving the property.

[0007]

Means for Solving the Problems As a result of solving the above problems and improving the heat generation durability of a tire without lowering the wear resistance and the fracture resistance, the present inventors have conducted diligent research, and as a result, It was found that the object can be achieved by compounding a specific amount of ISAF grade carbon black, the heat generation improver, and a relatively large amount of zinc white with a rubber component mainly composed of a diene rubber, and the present invention has been completed. .. That is, the present invention

(1) As a rubber component, 100 parts by weight of a rubber containing a diene rubber such as natural rubber, isoprene rubber, butadiene rubber, and styrene-butadiene copolymer as a main component is used for a nitrogen adsorption specific surface area (N ₂ SA). ) Is 110-1
70 m ² / g, oil absorption of dibutyl terephthalate (DB
P) is a carbon black alone or a blend with silica of 85 to 160 ml / 100 g, and the total amount of the reinforcing filler is 40 parts by weight or more and 70 parts by weight or less and the softening agent is 10 parts by weight or less. In the above, at least one selected from the chemical substances represented by the following general formula is 0.05 to 5
A heavy-duty tire in which a rubber composition prepared by coexisting in an amount of 5 to 15 parts by weight of zinc white is placed in a tire tread portion.

[Chemical 4]

[Chemical 5]

[Chemical 6] (In the formula, A is one selected from the group consisting of an aromatic ring, a substituted or unsubstituted hydantoin ring, and a saturated or unsaturated linear hydrocarbon having 0 to 18 carbon atoms; Is an aromatic group, the substituent X of B is at least one selected from a hydroxy group and an amino group, and Y is one selected from a pyridyl group and a hydrazino group.)

The nitrogen adsorption specific surface area (N ₂ SA) is A
According to the STM D3037-84B method, the dibutyl terephthalate oil absorption (DBP) was measured according to JIS K6221 (19).
82) It was measured by the method. Here, the amount of the chemical substance that is the heat generation improving agent is set to 0.05 to 5 parts by weight because the effect of improving the heat generation resistance is less than 0.05 parts by weight and the amount is more than 5 parts by weight. This is because the viscosity of the vulcanized rubber increases, which is not preferable from the viewpoint of workability. Therefore, 0.1 to 3 parts by weight is preferable.

The chemical substance particularly contributes to the dispersion of the rubber component and carbon black in the rubber composition,
The nitrogen adsorption specific surface area (N ₂ SA) of carbon black is 1
Less than 10 m ² / g, dibutyl terephthalate oil absorption (D
Carbon black with a BP) of less than 85 ml / 100 g has little effect of improving heat resistance, and N ₂ SA is 170 m.
^{If it} exceeds ² / g and the DBP exceeds 160 ml / 100 g, the viscosity of unvulcanized rubber increases, which is not preferable in terms of workability.

When the amount of the reinforcing filler, which is carbon black or a blend of carbon black and silica, is less than 40 parts by weight with respect to 100 parts by weight of the rubber component, abrasion resistance, cut resistance, and
If the required properties such as chipping resistance are not satisfied and the amount of heat generated exceeds 70 parts by weight, the effect of improving the heat resistance of the chemical substance is reduced.

If the amount of the softening agent such as process oil exceeds 10 parts by weight, all of the abrasion resistance, the cut resistance and the suppression of heat generation are disadvantageous.

On the other hand, it is considered that zinc white, which is a vulcanization accelerator, reacts with stearic acid, which is also a vulcanization accelerator, in the course of kneading to form zinc stearate, which contributes to the formation of a crosslinked network. .. In recent years, as a result of higher power and improved kneading efficiency of the Banbury mixer, which is a kneading machine, the amount of zinc white compounded has been reduced in consideration of the cost reduction and the demerit of zinc white as a foreign substance, and generally 5 wt. The following parts are recommended as optimal.

However, when a chemical substance is used in order to suppress heat generation in the compounding of the filler and the softening agent which are limited in the claims, the plasticity of the unvulcanized rubber increases and the charring of the rubber occurs during extrusion. However, it became necessary to reduce the extrusion rate. As a result of examining various compounding factors and the mechanism of increasing plasticity of chemical substances in order to solve this problem, it was confirmed that the relationship with the zinc white compounding amount was remarkable. That is, it was confirmed that when 5.5 to 15 parts by weight of zinc white was used, the compounding system of the present invention did not affect the productivity such as the extrusion speed.

[0015]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In heavy-duty tires, a rubber composition having a compounding formulation (parts by weight) shown in Table 1 was prepared mainly for confirming the effects of the chemical substances. The rubber composition of Table 1 was applied to the tire rubber member shown in FIG. 1 of a tire having a tire size of 18.00R25.

For each of the trial tires obtained, the tire temperature, the abrasion resistance of the tret portion, etc. were evaluated according to the following evaluation methods. (Tire Temperature) After a drum test under constant speed and step load conditions, temperature measurement was performed at a fixed position inside the tire tread. (Abrasion resistance of tread rubber) The tires after running for 2000 hours were compared for wear resistance and cut resistance of the tread rubber, and the tire of Comparative Example 1 was set as 100, and index evaluation was performed. The larger the number, the better the result.
The results obtained are shown in Table 2.

[Table 1]

[Table 2]

[0017]

As is clear from the examples and comparative examples, the heavy-duty tire of the present invention can suppress an increase in tire temperature without lowering wear resistance and fracture resistance, and can improve heat resistance of the tire. It is obvious to improve.

[Brief description of drawings]

FIG. 1 shows a half of a cross section of a heavy-duty tire, and (A) shows a tread portion which is a feature of the present invention.

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Claims (1)

[Claims] 1. A nitrogen adsorption specific surface area (N ₂ SA) per 100 parts by weight of a rubber containing a diene rubber such as natural rubber, isoprene rubber, butadiene rubber or styrene-butadiene copolymer as a main component as a rubber component. Is 110-170m
² / g, dibutyl terephthalate oil absorption (DBP)
85 to 160 ml / 100 g of carbon black alone or a blend with a reinforcing filler, which is a blend with silica, is 40 parts by weight or more and 70 parts by weight or less, and a softening agent 1
In an amount of 0 part by weight or less, 0.05 to 5 parts by weight of at least one selected from the chemical substances represented by the following general formula,
Also, a heavy duty tire in which a rubber composition formed in the coexistence of 5.5 to 15 parts by weight of zinc white is arranged in a tire tread portion. [Chemical 1] [Chemical 2] [Chemical 3] (In the formula, A is one selected from the group consisting of an aromatic ring, a substituted or unsubstituted hydantoin ring, and a saturated or unsaturated linear hydrocarbon having 0 to 18 carbon atoms; Is an aromatic group, the substituent X of B is at least one selected from a hydroxy group and an amino group, and Y is one selected from a pyridyl group and a hydrazino group.)