JPH02179517A - Radial tire - Google Patents

Abstract

PURPOSE:To improve both rim fitting property and rim runout resistance by making a bead surface rubber layer contain staples of a specified part by weight to the rubber component, and orienting the staples at a specified angle to the tire circumferential direction. CONSTITUTION:A tire has a carcass layer 4 turned up from the inside to the outside to enclose a bead filler around a bead wire 5. In this case, an anisotropic rubber layer G is disposed on the surface part from a bead toe part 11 to a bead heal part 12 forming a bead part 10. As a concrete means for setting the rubber layer G anisotropic, a large number of staples F are oriented in some direction within the range of -30 deg.-+30 deg. to the tire circumferential direction. The blending amount of the staples blended in the rubber layer G is set within the range of 2-30 parts by weight to 100 parts by weight of the rubber component. Hence, both rim fitting property and rim runout resistance are improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a tire rim fitability without reducing the rim fitability of the tire.
To provide a radial tire which is easy to assemble into a rim, and has good rim detachment resistance and does not easily come off after the tire is mounted on a vehicle.

[Conventional technology]

The bead toe of conventional radial tires is usually formed by the rubber at one end of the liner or the rubber covering the cord flowing in, and because no specific type of rubber is used for the bead toe, the internal pressure is extremely low. There was a possibility that the rim could come off while driving.

For this reason, Japanese Patent Application Laid-Open No. 54-88501 discloses a tire with improved rim detachment resistance, as shown in Figure 4.
A tire in which a bead toe portion 11 of a bead portion 10 is made of hard rubber has been proposed. However, although this tire has a considerable effect on improving the resistance to rim detachment, it has the disadvantage that the rigidity of the bead toe becomes too large, which reduces the fitability of the rim and reduces the workability of rim assembly. Ta. On the other hand, if the bending rigidity around the bead, especially the bending rigidity of the bead toe part, is lowered in order to improve the rim fitability, the compression rigidity and tensile rigidity of the bead toe part and a part of the bead under will decrease, resulting in a decrease in rim detachment resistance. . Therefore, rim fitability and rim detachment resistance are in an antinomic relationship, and improving both at the same time has been an important problem to be solved in tires.

[Problem to be solved by the invention]

An object of the present invention is to provide a radial tire that simultaneously improves both the rim fitting performance and the rim detachment resistance, which are in a trade-off relationship as described above.

(Means for Solving the Problems) The object of the present invention is to make at least the bead surface rubber layer from the bead toe part to the bead heel part contain 2 to 30 parts by weight of short fibers per 100 parts by weight of the rubber component, The short fibers are placed at an angle of -30° to +30'' with respect to the tire circumferential direction.
This can be achieved by orienting it at an angle of .

The radial tire referred to in the present invention includes a pair of bead parts,
It consists of a pair of sidewall parts connected to these bead parts and a tread part connecting between both sidewall parts, and a carcass layer is installed between the sidewall parts and one bead part in parallel to the cross-sectional direction of the tire, The carcass cord that forms the carcass layer, which refers to a tire in which a belt reinforcing layer is arranged between the carcass layer and the tread, is generally an organic fiber cord such as nylon or polyester fiber for passenger cars. , steel cord is used for heavy loads.

Furthermore, although steel cords are mainly used as reinforcing cords for the belt layer, organic fiber cords such as aramid fiber cords can also be used.

FIG. 3 is a cross-sectional view showing one example of the tire of the present invention. As shown in FIG.
The carcass layer 4 is folded back from the inside of the tire to the outside so as to wrap around the bead filler 6.6''.

Further, a sidewall portion 2.2” is provided in the tire side portion adjacent to the carcass layer 4. 10.
10'' indicates a bead portion which is an important component of the tire of the present invention.

In such a radial tire, as shown in FIG. 1, the present invention provides short fibers arranged in a certain direction on the surface area from the bead toe part 11 to the bead heel part 12 forming the bead part 10.10'. It is characterized by the arrangement of an anisotropic rubber layer.

That is, the present invention reduces the bending rigidity around the bead, which affects rim fitability, by arranging an anisotropic rubber layer from at least the bead toe to the bead heel, while reducing the bead toe, which is related to rim detachment resistance. The compressive rigidity and tensile rigidity of the bead under part and the bead under part are increased, and rim fitability and rim detachment resistance are improved at the same time.

As a specific means for making the rubber layer G from the bead toe section 11 to the bead heel section 12 anisotropic, the short fibers (F) are oriented in a direction in the range of -30° to +306 degrees with respect to the tire circumferential direction. It is something.

In the illustrated embodiment, the anisotropic rubber layer G is located above the bead wire 5 on the inner surface of the tire around the bead toe section 11, and the bead heel section 1 is located on the lower surface of the bead section 10.
It has reached 2.

FIG. 2 shows an anisotropic rubber layer G containing the above-mentioned short fibers (F).
FIG.

As shown in FIG. 1, the anisotropic rubber layer G may be disposed only on the surface layer portion, or may be disposed on the entire rubber layer from the bead toe portion 11 to the bead heel portion 12.

The amount of short fibers added to the anisotropic rubber layer G needs to be 2 to 30 parts by weight per 100 parts by weight of the rubber component. If the blending amount of the short fibers is less than 2 parts by weight, the difference in elastic modulus between the orientation direction of the short fibers in the rubber layer and the direction perpendicular thereto is small, and sufficient anisotropy cannot be imparted to the rubber layer. Moreover, if it exceeds 30 parts by weight, the processability of the rubber composition will be significantly reduced, which is not preferable.

Further, it is important that the orientation angle of the short fibers (F) in the rubber layer □ is within the range of -30° to +30° with respect to the tire circumferential direction. Most preferably, θ with respect to the tire circumferential direction
° It is to do. That is, as described above, in order to improve the rim fitability, it is necessary to lower the tensile rigidity in the cross-sectional direction of the bead toe portion 11, which greatly affects the bending rigidity around the bead, and to improve the rim detachability. In order to
This is because it is necessary to increase the compressive rigidity and tensile rigidity of the tire.For this reason, it is necessary to increase the compressive rigidity in the tire radial direction and the tensile rigidity in the tire circumferential direction of the bead toe part 11 and the bead under part 13. This is not the case.

When such an anisotropic rubber layer G in which the orientation angle of the short fibers with respect to the tire circumferential direction is within the range of 130 @ to +30 @ is arranged at least in the bead toe part, the tensile rigidity of the bead toe part with respect to the cross-sectional direction of the tire is The compressive stiffness in the radial direction of the tire and the tensile stiffness in the circumferential direction of the tire increase at the bead toe and part of the bead toe, so there is no decrease in fitability with the rim, and the resistance to rim detachment is improved. can be improved.

Furthermore, the shape of the short fibers is preferably such that the ratio (j!/d) of the short fiber length (I) to the average diameter (d) is 15 or more. This ratio (f/d) is 15 or more. This is because, by doing so, the reinforcing effect of the anisotropic rubber layer can be enhanced and the effect of the above-mentioned anisotropy can be emphasized.

Moreover, the average diameter (d) of short fibers is 15. This is because by setting the average diameter (d), which is preferably equal to or less than u, to 15μ or less, deterioration in crack resistance and tire durability can be prevented.

Here, the average diameter (d) is a statistically determined value obtained by randomly sampling 20 short fibers to be mixed into the raw rubber, measuring the diameter, and dividing the sum by the total number.

The above-mentioned short fibers may be either organic fibers or inorganic fibers.The organic fibers may be used during tire running or when the rubber composition containing the short fibers is mixed in a mixer etc. In order to prevent the reinforcing effect from being reduced due to melting or thermal deterioration due to (reaching 160° C.), it is desirable that the melting point is 160° C. or higher. Examples of such short fibers include organic fibers such as vinylon, nylon, polyester, aromatic polyamide (aramid), and fully aromatic polyester, rayon, carbon fiber, glass fiber, potassium titanate, silicon carbide, and phosphorus. Examples include whisker-type inorganic fibers such as phate. These fibers can be treated with various adhesives to improve their adhesion to rubber, and these fibers can be used alone or in small numbers with different fiber types, fiber lengths, and fiber diameters. Both can be used in combination of two or more.

The rubber component in which these short fibers are blended is not particularly limited, and includes, for example, natural rubber (NR), nitrile-butadiene rubber (NBR), isoprene rubber (IR), butadiene rubber (BR), and styrene-butadiene copolymer. Examples include composite rubber (SIR) and isobutylene-isoprene rubber (IIR). Furthermore, it goes without saying that various known compounding agents such as various carbon blacks, anti-aging agents, and vulcanization accelerators may be appropriately blended.

〔Example〕

Hereinafter, the effects of the present invention will be explained in more detail with reference to Examples.

The rim detachment resistance of each tire was evaluated by the following J-shaped turning test, and the rim fitability was evaluated by the following measurement of fitting pressure.

Yushiki 1 [Skin swelling: A test tire using a rim of 61/2 JJ
A test course consisting of a semicircle of m and a straight line tangent to it is 3.
Driving at a speed of 5.5 Km/hr, the air pressure of the front left tire of the test vehicle was set to 2.0 and the pressure was increased from gnome C11'' to 0.1K.
The air pressure was measured by decreasing the air pressure by "g/cm" at a time when rim touch or rim detachment occurred.

The test was conducted at each air pressure (2.0Kg/cm", 1.9Kg/cm",
cm”.

1.8Kg/cm"+ 1.7Kg/cs", 1.6
Kg/cm") was performed five times and expressed as an index (reciprocal) using the value of the conventional tire as a reference (100). The larger the index value, the better the rim detachment resistance.

The test tire was mounted on a 61/2 J, r x 15 rim, air was injected, and the air pressure when the tire was fitted to the rim was measured.

This measurement is performed five times for each test tire, and the average value of the three measurements excluding the highest and lowest values is taken as the fitting pressure of that tire, and the index is based on the value of the conventional tire (100). It was displayed in The smaller the index value, the better the rim fitability.

Examples 1-2, Conventional Example, Comparative Example Three types of rubber compositions having different formulations shown in Table 1 were prepared.

As the rubber layer covering the bead portion of the tire shown in Fig. 3, three types of tires were used, in which the rubber composition and the orientation angle of the short fibers shown in Fig. 2 were made different as shown in Table 2. Created.

The tire size is the same for both 195/65 VR15
It is.

Also, for comparison, (
The same conventional tire was prepared except that the rubber composition of 1) was used to form one rubber layer.

These tires were evaluated for rim detachment resistance and rim fitability, and the results shown in Table 2 were obtained.

Table 1 All numerical values in the table are parts by weight.

I' is styrene-butadiene copolymer rubber (Nipo
l 1502 Nippon Zeon ■), Ri is N-(1,3-
dimethylbutyl)-N-phenyl-p-phenylenediamine, 3) is a carbon fiber with an average diameter of 7 μm and an average fiber length of 61III*, 4) is a wholly aromatic polyamide fiber with an average diameter of 12 μm and an average fiber length of 3 mm, ! + indicates N-oxydiethylene-2-benzothiazylsulfenamide (blank space below this page) Table 2 From Table 2, it can be seen that the tires 1 and 2 of the present invention have almost the same rim fitability as the conventional tire. However, it can be seen that it is significantly superior in rim detachment resistance.

On the other hand, in a comparative tire in which the orientation angle of the short fibers is outside the angle specified in the present invention, the rim slip-off resistance is improved, but the rim fitability is reduced.

〔Effect of the invention〕

According to the present invention, a predetermined amount of short fibers are blended as the rubber layer from at least the bead toe portion to the bead heel portion of the pneumatic tire, and the short fibers are given a predetermined orientation angle to make them anisotropic. It is possible to increase the compressive rigidity and tensile rigidity of the bead toe and part of the bead under without changing the bending rigidity around the bead.
It is possible to significantly improve the resistance to rim detachment without impairing the fitability of the tire to the rim.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of a bead portion of a pneumatic tire of the present invention, FIG. 2 is a perspective view of an anisotropic rubber layer provided on the bead portion of FIG. 1, and FIG. FIG. 4 is a partial cross-sectional view of a bead portion of a conventional tire, and FIG. 5 is a schematic diagram of a test course for a J-shaped turning test. 3... Bead wire, 4... Carcass layer, 7u, 7
d... Belt layer, 11... Bead toe portion, 12...
・Bead heel part, 13...Bead under part, G・
...Rubber layer, F...short fiber. Agent Patent Attorney Nobuo Ogawa −

Claims (1)

[Claims] 2 to 30 per 100 parts by weight of the rubber component in at least the bead surface rubber layer from the bead toe to the bead heel.
A radial tire comprising a weight part of short fibers and oriented at an angle of -30° to +30° with respect to the circumferential direction of the tire.