JPH0345402A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE:To enhance wear resistance without impairing gripping properties and the like by setting up the tension elasticity ratio of the radial direction of a tire to the circumferential direction of it at a specified value or larger in rubber composition forming a tread section. CONSTITUTION:A tire is equipped with belts (not shown) located at the outer circumferential surfaces of carcass plies which are substantially arranged in the radial direction, and with a tread which is located at the outer circumferential surface while tread grooves 7 are provided for the outer surface of the tread. In this case, the tension elasticity ratio of the radial direction of the tire to the circumferential direction of it for rubber composition forming the tread is set up at 1.5 or larger when it is extended by 200% in length at 100 deg.C. This causes fillers 8 to be attached, in which short fibers, for example, are being faced to one another. By this constitution, wear resistance can thereby be enhanced without impairing the gripping properties and the traction of the tire.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a pneumatic radial tire with improved wear resistance without sacrificing grip or traction.

(Conventional technology) With the development of automobile technology such as higher engine output and higher performance chassis, tires with high grip performance are required, but tires with such high maneuverability have a grip limit. Because they are generally driven more frequently than regular tires, they wear out faster, which is a problem.

Furthermore, even with general tires, for example in the case of front-wheel drive vehicles, large loads and side forces are applied to the front tires at the same time, and wear life is also a problem.

JP-A-58-1734 describes a rubber with large hysteresis as a tire rubber composition having excellent grip performance as described above. Furthermore, in order to obtain rubber with good wear resistance, carbon black with high reinforcing properties is generally used, or polymers with a low glass transition point (Tg) such as butadiene rubber (BR) are used.

Further, it is known, for example, in JP-A-57-10632, that the reinforcing properties of a rubber composition are improved by blending isotactic polypropylene staple fibers or syndiotactic 1,2-polybutadiene staple fibers into the rubber composition. It is also known to use this as a tread rubber composition (for example, JP-A-57-1514
No. 05, Japanese Unexamined Patent Publication No. 119409/1982).

(Question 8 to be solved by the invention) However, the conventional techniques were not always satisfactory.

In other words, if the amount of softener or reinforcing agent is increased relative to the polymer in order to obtain a rubber with large hysteresis, and if the amount is added in excess of the appropriate amount, the fracture strength will decrease and the blowout resistance will also decrease, making it difficult to continue sharp cornering. It becomes difficult, and wear resistance also deteriorates significantly.

Furthermore, if a large amount of carbon black, which has strong reinforcing properties, is blended in order to improve the abrasion resistance, the rubber composition becomes hard and grip properties become difficult to obtain. Similarly, even if a polymer with a low Tg such as BR is used, the coefficient of friction μ will be low, resulting in a decrease in grip performance.

Furthermore, conventional examples of increasing the reinforcing properties of rubber compositions by blending isotactic polypropylene staple fibers or syndiotactic 1,2-polybutadiene staple fibers into rubber Ua products include conventional tread extrusion and sheet extrusion molding. Since the product was used as a tread as is, the tread rubber composition was oriented in the circumferential direction of the tire, making it impossible to take advantage of the characteristics of the short fiber reinforced rubber composition.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a pneumatic radial tire with improved wear resistance without sacrificing grip and traction.

(Means for Solving the Problems) In order to achieve the above object, a belt located on the outer peripheral surface of carcass plies arranged substantially in the radial direction;
In the pneumatic radial tire of the present invention, which is provided with a tread located on the outer peripheral surface of the heald and having tread grooves on the outer surface, the rubber composition constituting the trend is heated at 100°C.
The tire is characterized in that the ratio of the tensile modulus at 200% elongation in the tire radial direction to the circumferential direction is 1.5 or more.

In the present invention, the rubber composition has a temperature of 200°C at 100°C.
The reason why the ratio of the tensile modulus at % elongation between the tire radial direction and the circumferential direction is set to 1.5 or more is as follows.

In other words, especially in driving conditions where a large side force is applied continuously such as during sports driving, or where side force is applied under a large load such as on the front tires of a front-wheel drive vehicle, or on the front of a truck or bus. When the side force is large, such as on tires, tread wear progresses in the radial direction of the tire. Furthermore, as a result of intensive studies by the present inventors, it was found that the wear resistance under such conditions can be evaluated by the tensile elastic modulus during large deformation at high temperature. That is, 100 in the tire radial direction
By selectively increasing the tensile modulus at 200% elongation at C in the circumferential direction, that is, by setting the ratio of the tire radial direction to the circumferential direction to 1.5 or more, resistance to such wear can be improved. It has been found that a significant improvement in wear properties can be achieved.

The unvulcanized tread molded product of the present invention may be laminated after cutting the unvulcanized tread molded sheet in a direction perpendicular to the sheet direction, or the unvulcanized tread molded product can be formed by cutting the large extrusion with a skiver perpendicular to the extrusion direction. You can also manufacture things.

In order to make the ratio of the radial to circumferential tensile modulus at 200% elongation at 100°C to 1.5 or more, a method such as orienting short fibers or resin in the rubber composition constituting the tread is adopted. be able to.

(Examples) Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Short fiber-reinforced rubber containing fillers that were kneaded with natural rubber at temperatures above their respective melting points to form short fibers as shown in Table 1 below was prepared.

These were blended in a conventional manner with the ingredients and blending ratios shown in Table 2 below to obtain a rubber composition constituting a tread.

Table 1 Table 2 Table 1) Cold oil expansion with bound styrene amount of 35.0 wt% 5
BR (manufactured by B Honhei Rubber, oil expanded, 5 parts by weight) Umbrella 2)
Bonded styrene amount (%) Non-oil-extended cold SBR (Japanese Synthetic Rubber ■ button *3) N-(1,3-dimethyl-butyl)N'-phenylene diamine (Monsanto Co. ll) * 4) Tetramethylthiuram disulfide umbrella 5) N-cyclohexyl-2-benzothiazolyl sulfenamide *6) N-oxydiethylene-2-benzothiazole sulfenamide Each rubber composition shown in Table 2 was rolled out in the drawing direction. A rubber sheet oriented to
The tread contour of the green tire was created by layering these rubber sheets. All other tires were prototyped using conventional methods. FIG. 1 is a sectional view of an embodiment of a pneumatic tire according to the present invention. In FIG. 1, a pneumatic tire 1 according to the present invention has a bead wire 3 located at a bead portion 2.
Then, both ends are folded back at the bead part 2 to form a bead wire 3.
The carcass ply 4 is engaged with the carcass ply 4, the belt 5 is located on the outer peripheral surface of the carcass ply 4, and the tread 6 is located on the outer peripheral surface of the belt 5 and has tread grooves 7 on the outer surface.

FIG. 2 is a plan view of a tread of an embodiment of a pneumatic tire according to the present invention. In FIG. 2, the rubber composition constituting the tread 6 having tread grooves 7 on the outer surface has a tensile modulus of elasticity in the radial and circumferential directions at 200% elongation at 100° C. due to the filler 8 in which the short fibers are oriented. The ratio is 1.5 or more. Performance evaluation of these tires was performed by the following method.

Using a flat belt manufactured by MTS, the CF was compared when the slip angle was gradually increased at a speed of 50 km/hour and a load of 500 kg.

A prototype tire was installed on an actual vehicle and the amount of tread remaining after driving for 5,000km, including sharp cornering, was compared.

The ratio of the tensile modulus of the rubber composition constituting the tread at 200% elongation at 100"C in the tire radial direction and the circumferential direction is determined by dissecting the tread of a prototype tire and
A test piece specified by IN was taken out and measured according to the DIN test method, and the ratio was calculated.

In Example 1, Rubber Composition C was used and the elastic modulus ratio was set to 1.5 or more. Example 2 uses a rubber composition in which the ratio of elastic modulus is 1.5 or more. In Example 3, rubber composition E was used and the elastic modulus ratio was set to 1.5 or more.

Kita Doken [L-E Comparative Example 1 uses rubber composition A and has an elastic modulus ratio of 1.
．． It is smaller than 5. Comparative Example 2 uses rubber composition B and has an elastic modulus ratio of less than 1.5.

Above Examples 1 to 3, Comparative Example 1.2't' is 205/60
A tire trial was made with a tire size of R15, and the performance of the tire of Comparative Example 1 was set as 1oo, and the grip properties and abrasion resistance evaluated by the above method were each expressed as an index. The larger the number, the better the result. Table 3 shows the tire test results.

In Example 4, Rubber Composition H was used and the elastic modulus was set to 1.5 or more. In Example 5, the rubber composite material I was used and the elastic modulus ratio was 1.5 or more. In Example 6, rubber composition J was used and the elastic modulus C ratio was set to 1.5 or more.

Comparative unevenness 1-soil Comparative example 3 uses rubber composition F and has a ratio of elasticity etc. of 1.
．． It is smaller than 5. Comparative Example 4 uses Comb Composition G and has an elastic modulus ratio of less than 1.5.

165/7011 in Examples 4 to 6 and Comparative Examples 3 and 4 above
A trial tire was made with a tire size of 3, and the performance of the comparative Italian tire 3 was set as 100, and the performance was evaluated using the C index as in Example I. Table 4 shows the tire test results.

Table 1 As can be seen from Tables 3 and 4 above, Examples 1-
The tire of the present invention of No. 6 was able to improve the wear resistance without sacrificing the grip property.

(Effects of the Invention) As explained above, in the pneumatic radial tire of the present invention, wear resistance can be improved without sacrificing grip performance or traction.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a pneumatic tire according to an embodiment of the present invention, and FIG. 2 is a plan view of a tread of a pneumatic tire according to an embodiment of the present invention. 1... Pneumatic tire 2... Bead portion 3...
Heat wire 4... Carcass ply 5... Belt 6... Tread 7... Trend groove 8... Filler with oriented short fibers Fig. 1

Claims (1)

[Claims] 1. A pneumatic radial comprising a belt located on the outer peripheral surface of carcass plies arranged substantially in the radial direction, and a tread located on the outer peripheral surface of the belt and having tread grooves on the outer surface. A pneumatic radial tire, characterized in that the ratio of the tensile modulus of the rubber composition constituting the tread at 200% elongation at 100° C. in the tire radial direction to the circumferential direction is 1.5 or more.