JP2006076407A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of reducing the rolling resistance without sacrificing other physical properties. <P>SOLUTION: The pneumatic tire 10 is structured so that a cap ply 30 formed by embedding organic fiber cords 32 stretching in the tire circumferential direction A is installed between a tread rubber 26 and a belt layer 24 provided inside the tread rubber in the radial direction, wherein the topping rubber 34 of the cap ply 30 covering the cords 32 is formed from a rubber compound consisting of 100 parts by weight diene series rubber and 1-10 parts by weight short fibers 36 of aramid or 6-nylon fibers, and the short fibers 36 are oriented in the tire circumferential direction A. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pneumatic tire with reduced rolling resistance.

  Conventionally, examples of pneumatic tires with reduced rolling resistance include those disclosed in Japanese Patent Application Laid-Open Nos. 2003-183442 and 2003-146015. These have a tread rubber composition and a tire structure having a unique configuration and shape, and exhibit an effect of reducing rolling resistance. Therefore, these techniques are difficult to apply to existing tread rubber blends and tire structures.

  On the other hand, in the cap ply provided between the tread rubber and the belt layer as listed in Patent Document 1 below, the configuration of the cord used and the arrangement thereof are regulated to effectively reduce the road noise. There is a technology that suppresses the deterioration of passing noise and rolling resistance. According to this method, application to an existing tire is relatively easy, but there is a problem that an existing tire having a cap ply must be newly reconfigured.

  In Patent Document 2 below, as a belt layer, an organic fiber cord running in the tire circumferential direction is covered with rubber, and the rubber is made to contain short fibers oriented at a predetermined angle with respect to the tire circumferential direction. Technology is disclosed. However, this method involves a significant change in the configuration of the belt layer and is difficult to apply to existing tires.

Further, Patent Document 3 below discloses a technique in which short fibers are contained in a rubber reinforcing layer disposed between a tread rubber and a belt layer. The rubber reinforcing layer includes a cord that runs in the tire circumferential direction. Therefore, the restraining force in the tire circumferential direction is insufficient, and the rolling resistance reduction effect is not satisfactory.
JP 2003-63210 A JP-A-6-191213 JP-A-9-136508

  In view of the above points, the present invention replaces an unvulcanized rubber compounded with short fibers with a rubber that is topped on an existing cap ply, and only changes a small amount of rubber without sacrificing other physical properties. An object of the present invention is to provide a pneumatic tire capable of reducing rolling resistance.

  The pneumatic tire according to the present invention is a pneumatic tire in which a cap ply formed by burying a cord running in the tire circumferential direction is disposed between a tread rubber and a belt layer disposed radially inwardly. The cap ply topping rubber covering the cord is composed of a rubber composition in which 1 to 10 parts by weight of short fibers are blended with 100 parts by weight of diene rubber, and the short fibers are oriented in the tire circumferential direction. It is characterized by that.

  In the pneumatic tire of the present invention, the short fiber is preferably at least one selected from the group consisting of an aramid short fiber and a 6-nylon short fiber. The short fibers preferably have a fiber diameter D of 0.05 to 15 μm, a fiber length L of 0.001 to 5 mm, and a ratio L / D of 50 to 400 of both.

  According to the present invention, in a cap ply formed by burying a cord running in the tire circumferential direction, a predetermined amount of short fibers oriented in the tire circumferential direction are blended in the topping rubber covering the cord, thereby the tire width direction. It is possible to increase the restraining force in the tire circumferential direction without changing the restraining force in the vehicle, and thus effectively reduce the rolling resistance without sacrificing other physical properties such as ride comfort. be able to.

  Next, a pneumatic tire according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a half cross-sectional view of a pneumatic radial tire 10 according to the embodiment. The tire 10 includes a pair of left and right bead portions 12 and sidewall portions 14, and a tread portion 16 straddling both sidewall portions 14. It is prepared for.

  The bead portion 12 is provided with an annular bead core 18, and a rubber bead filler 20 is disposed on the outer periphery in the radial direction. Between the pair of left and right bead cores 18 is provided a carcass layer 22 formed of at least one carcass ply formed by extending a large number of cords arranged at right angles to the tire circumferential direction. The both end portions are folded and locked by a bead core 18 and a bead filler 20. A belt layer 24 is disposed outside the carcass layer 22 in the tread portion 16 in the radial direction, and a tread rubber 26 is provided outside the belt layer 24 in the tire radial direction. The belt layer 24 is formed by superimposing at least two belt plies 24a and 24b in which non-extensible cords made of metal or the like are inclined and arranged at a shallow angle with respect to the tire circumferential direction so that the cords intersect.

  In such a configuration, between the tread rubber 26 and the belt layer 24 arranged on the inner side in the radial direction, a reinforcing layer made of a cord-rubber composite covering the substantially entire width of the belt layer 24 is provided. A cap ply 30 is provided. A part of the cap ply 30 is enlarged as shown in FIG. 2, and a cord array formed by aligning cords 32 running in the tire circumferential direction A at a predetermined interval in the tire width direction is formed with a topping rubber 34. The front and back are covered. Here, an organic fiber cord such as nylon fiber or polyester fiber is used as the cord 32, and the organic fiber cord is arranged in parallel to the tire circumferential direction A (tire equator direction). The method for forming the cap ply 30 is not particularly limited. For example, a tape-like material in which one or a plurality of cord alignment members are embedded in a topping rubber is spirally wound outside the belt layer. It can be formed by turning.

  In the present embodiment, the topping rubber 34 includes the short fibers 36 oriented in the tire circumferential direction A, whereby the binding force of the cap ply 30 in the tire circumferential direction A is improved.

  As the topping rubber 34, a rubber composition in which 1 to 10 parts by weight of the short fiber 36 is blended with 100 parts by weight of the diene rubber is used. If the blended amount of short fibers is less than 1 part by weight, the restraining force is not sufficiently increased in the tire circumferential direction, and the effect of reducing rolling resistance is not recognized. If the amount exceeds 10 parts by weight, the effect of reducing rolling resistance has reached its peak. On the other hand, other physical properties such as deterioration of ride comfort are deteriorated. A more preferable blend amount of the short fibers is 2 to 8 parts by weight with respect to 100 parts by weight of the diene rubber.

  Although it does not specifically limit as the short fiber 36, It is preferable to use an organic short fiber, It is preferable to use especially a polyamide fiber, and more specifically, an aramid short fiber and a 6-nylon short fiber. The aramid fiber and the 6-nylon short fiber may be used alone or in combination. Moreover, as the short fiber 36, it is preferable to use a fiber having a fiber diameter D of 0.05 to 15 μm, a fiber length L of 0.001 to 5 mm, and a ratio L / D of 50 to 400 of both. More preferably, the fiber diameter D is 0.1 to 10 μm, the fiber length L is 0.002 to 4 mm, and L / D is 70 to 250. By using the thing within such a range, the restraining force in the tire circumferential direction can be effectively increased.

  As the diene rubber, various diene rubbers such as styrene butadiene rubber, butadiene rubber, natural rubber, and isoprene rubber can be used singly or in combination. The rubber composition may contain various additives used in tire rubber compositions such as sulfur, vulcanization accelerator, zinc white, stearic acid, carbon black, softener, and anti-aging agent. . In particular, when nylon short fibers are used as the short fibers 36, it is preferable to add a crystalline resin such as an olefin resin in order to improve the adhesiveness between the short fibers and the rubber. (HDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), polypropylene (PP), and the like, and HDPE is particularly preferable.

  In order to set the orientation direction of the short fibers 36 to the tire circumferential direction A (tire equator direction), the following may be performed. That is, when the topping rubber is molded using an extruder, the short fibers blended in the rubber composition are arranged in the transport direction, that is, the row direction, so that the longitudinal direction (row direction) of the extrudate is The cord 32 may be covered with the topping rubber 34 so as to coincide with the arrangement direction of the cord 32 described above. Since the cord 32 is disposed so as to extend in the tire circumferential direction A as described above, the orientation method of the short fibers 36 is also oriented in the tire circumferential direction.

  In the pneumatic tire of the present embodiment configured as described above, in the cap ply 30 in which the cord 32 running in the tire circumferential direction A is embedded, the short fibers 36 oriented in the tire circumferential direction A are disposed on the topping rubber 34. By incorporating the fixed amount, the restraining force in the tire circumferential direction A by the cord 32 can be further increased by the short fibers 36 oriented in the same direction, and the restraining force in the tire width direction is substantially changed. Can not be. Therefore, it is possible to effectively reduce rolling resistance without sacrificing other physical properties such as riding comfort. In particular, in existing tires with cap plies with cords that run in the tire circumferential direction, rolling resistance can be reduced without changing other physical properties by simply changing the short fibers in the top ply rubber of the cap ply. This can be reduced and is effective in improving the fuel efficiency of such existing tires.

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

(Measurement of rubber properties)
The rubber compositions of Examples 1 and 2 and Comparative Examples 1 to 6 were prepared according to the formulation shown in Table 1 below. In Table 1, natural rubber is RSS3, carbon black is N330 manufactured by Tokai Carbon, anti-aging agent is "NOCRACK 6C" manufactured by Ouchi Shinsei Chemical, stearic acid is cobalt stearate manufactured by Japan Energy, and vulcanization acceleration The agent is “Noxeller DZ-G” manufactured by Ouchi Shinsei Chemical. The aramid short fiber is “Tauron 1091” manufactured by Teijin Limited, and the fiber length / fiber diameter (L / D) = 1.3 mm / 10 μm = 130. Nylon short fiber master batch “HA1060” (natural rubber / high-density polyethylene / 6-nylon = 38/29/33 (% by weight)) manufactured by Ube Industries, Ltd. is used as the nylon short fiber. Indicates the amount of 6-nylon short fibers, and in this case, the amount of natural rubber in the table is the total amount of the amount of RSS3 and the amount of natural rubber contained in the masterbatch. The fiber length / fiber diameter (L / D) of the 6-nylon short fiber is 0.020 mm / 0.2 μm = 100.

  For each rubber composition, an unvulcanized rubber having a width of 150 mm × thickness of 1.3 mm was prepared using a 12 inch roll, and a mold having a thickness of 1 mm was used under vulcanization conditions of 140 ° C. × 50 minutes. And press vulcanized to prepare a sample. The sample was then measured for hardness (based on JIS K6253), tensile properties (100% modulus, breaking strength and breaking elongation, based on JIS K6251), and exothermic properties (based on JIS K6265). All the results were displayed as indices with the value of Comparative Example 1 as 100. The results are shown in Table 1.

(Evaluation of tire performance)
Tire size with a cap ply formed by embedding nylon fiber cords of 1400 dtex / 2 running in the tire circumferential direction at intervals of 28/25 mm using each rubber composition as a top ply rubber for a cap ply: 195 A / 65R15 pneumatic radial tire was produced. The configuration excluding the topping rubber was the same in Examples 1 and 2 and Comparative Examples 1-6.

  The produced tire was subjected to a fuel consumption test and a ride comfort evaluation test. The results are shown in Table 1. Each test method is as follows.

Fuel consumption test: An index display in which the value of Comparative Example 1 was set to 100 was performed in accordance with American Automobile Engineers Association Standard SAE J1269. The smaller the index, the better the fuel economy.

・ Riding comfort evaluation test: The prepared tire was mounted on a 2000cc domestic passenger car, and the driver in charge of driving drove it on the circuit for sensory evaluation of riding comfort. Evaluation is performed by a 10-point method, and the higher the value, the better the ride comfort.

  As shown in Table 1, in the tires of Examples 1 and 2 in which short fibers were blended with the topping rubber, the fuel efficiency was significantly improved without impairing the riding comfort as compared with the tire of Comparative Example 1. . On the other hand, Comparative Examples 2 and 4 with a small amount of short fibers showed no improvement effect on fuel efficiency, and Comparative Examples 3 and 5 with a large amount of short fibers had excellent fuel efficiency but riding comfort. Sex was getting worse. Further, in Comparative Example 6 in which the amount of carbon black was increased to make the hardness the same level as in Examples 1 and 2, the fuel efficiency was deteriorated.

1 is a half sectional view of a pneumatic tire according to an embodiment of the present invention. It is a partially expanded perspective sectional view of the cap ply of the embodiment.

Explanation of symbols

10 …… Pneumatic tire 24 …… Belt layer 26 …… Tread rubber 30 …… Cap ply 32 …… Cord 34 …… Topping rubber 36 …… Short fiber A …… Tire circumferential direction

Claims (3)

A pneumatic tire in which a cap ply formed by burying a cord running in the tire circumferential direction is disposed between the tread rubber and a belt layer disposed on the inner side in the radial direction,
The top ply rubber of the cap ply covering the cord is composed of a rubber composition in which 1 to 10 parts by weight of short fibers are blended with 100 parts by weight of diene rubber, and the short fibers are oriented in the tire circumferential direction. A featured pneumatic tire.   2. The pneumatic tire according to claim 1, wherein the short fibers are at least one selected from the group consisting of aramid short fibers and 6-nylon short fibers. The short fiber has a fiber diameter D of 0.05 to 15 µm, a fiber length L of 0.001 to 5 mm, and a ratio L / D of 50 to 400 of both. Pneumatic tire.

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