JP5007545B2 - Pneumatic radial tire - Google Patents

Description

  The present invention has a good medium frequency road noise reduction effect and excellent durability against separation performance of the belt edge cover portion cord, and thus excellent durability of the medium frequency road noise reduction effect. The present invention relates to a pneumatic radial tire.

  If organic fiber cords are used as the belt edge cover for the purpose of reducing medium frequency road noise, the rubber between the belt edge and the belt edge cover due to the difference in rigidity between the belt edge rubber and the belt edge cover. It was found that there was a problem that separation of organic fiber cords was likely to occur in the belt edge cover part.

  If separation of the organic fiber cord occurs in this belt edge cover, the strength of the organic fiber cord decreases due to stress concentration and the durability performance deteriorates. By covering the belt edge with the organic fiber cord, the medium frequency load It was also found that the desired effect of reducing noise could not be maintained over a long period of time.

  On the other hand, as an invention preceding the pneumatic radial tire of the present invention, which will be described later, a pneumatic radial tire using a steel cord having a unique twist structure as a belt layer has been proposed (Patent Documents 1-4).

However, no special investigation has been made on the belt cover layer as in the pneumatic radial tire of the present invention described later.
JP-A-5-301505 Japanese Patent Laid-Open No. 6-128883 JP-A-7-1911 Japanese Patent Laid-Open No. 9-119081

  The object of the present invention is to make the cord used for the belt cover layer unique, to achieve a good effect of reducing the medium frequency road noise, and to be excellent in durability of the separation resistance of the belt edge cover portion cord. An object of the present invention is to provide a pneumatic radial tire excellent in durability of the effect of reducing the intermediate frequency road noise.

  The pneumatic radial tire of the present invention that achieves the above-mentioned object has the following configuration (1).

(1) A pneumatic radial tire in which an organic fiber cord having a 2 + 1 structure is wound as a belt cover layer on at least a belt edge portion of the belt layer.

  In the pneumatic radial tire of the present invention, a more specifically preferable configuration is any one of the following (2) to (6).

(2) The pneumatic radial tire according to (1), wherein the organic fiber cord having a 2 + 1 structure is a high elastic modulus organic fiber cord having an elastic modulus of 4.5 to 18.0 GPa.

(3) An organic fiber cord having a 2 + 1 structure is selected from nylon 6 fiber, nylon 66 fiber, polyethylene terephthalate fiber, polyethylene naphthalate fiber, polyolefin ketone fiber, polyvinyl alcohol fiber, aramid fiber, and rayon fiber, or The pneumatic radial tire according to (1) or (2), wherein the pneumatic radial tire is a plurality of types.

(4) The pneumatic radial tire according to any one of (1) to (3), wherein the organic fiber cord is made of polyethylene naphthalate fiber.

(5) The pneumatic radial tire according to any one of the above (1) to (3), wherein the organic fiber cord is made of a polyolefin ketone fiber.

(6) The pneumatic radial tire according to any one of (1) to (5) above, wherein the cord constituting the belt layer is a steel cord having a 2 + 1 structure.

  According to the pneumatic radial tire of the present invention according to claim 1, it has excellent medium frequency road noise resistance performance and separation durability performance of the belt edge cover part cord, and thus the above-mentioned excellent medium frequency road noise performance. It is possible to provide a novel pneumatic radial tire with good durability performance.

  According to the pneumatic radial tire of any one of claims 2 to 6, the effects of the present invention described above can be exhibited more clearly and greatly, which is preferable.

Hereinafter, the pneumatic radial tire of the present invention will be described in more detail.
The pneumatic radial tire of the present invention is formed by winding an organic fiber cord having a 2 + 1 structure as a belt cover layer on at least a belt edge portion of a belt layer.

  FIG. 1 is a tire meridian cross-sectional schematic diagram illustrating an example of an embodiment of a pneumatic radial tire according to the present invention, where 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion. A carcass layer 4 made of an organic fiber cord is embedded in the tire so as to cover the tread portion 1, the left and right sidewall portions 2, and the entire bead portion 3. A belt layer 6 is provided on the carcass layer 4 (on the outer periphery). The belt layer 6 may be the two layers illustrated, but may be one layer or three or more layers.

  In such a basic structure, the pneumatic radial tire of the present invention is provided with the belt cover layer 7 that covers both edge portions of the belt layer 6 on the outer peripheral side of the belt layer 6 provided on the outer periphery of the carcass layer 4. The belt cover layer 7 is made of a 2 + 1 structure organic fiber cord and matrix rubber, and is wound around the tire circumferential direction.

  The organic fiber cord having the 2 + 1 structure is preferably wound so as to be substantially parallel to the tire circumferential direction.

  Particularly preferably, as the organic fiber cord having the 2 + 1 structure, a high elastic modulus organic fiber cord having an elastic modulus of 4.5 to 18.0 GPa is used, and such a high elastic modulus organic fiber cord is used. As a result, it is possible to obtain a better medium frequency road noise resistance performance.

  In the radial tire of the present invention, the 2 + 1 structure organic fiber cord used for the belt cover layer is formed by winding one organic fiber side strand around the two core strands made of organic fiber at a loose pitch. However, the organic fiber cord having the 2 + 1 twist structure generally has an uneven structure on the entire cord surface that is significantly larger than that of other twist structures, and the cord itself exhibits this uneven structure. , Separation crack propagation is less likely to occur, and cord separation in the belt cover layer using the cord is much less likely to occur than when using other twisted structure cords, and the medium frequency load resistance is extended over a longer period of time. Noise performance can be demonstrated.

  In the present invention, it is preferable to use a material having an elastic modulus in the range of 4.5 to 18.0 GPa, as described above, in order to obtain the effect of reducing the medium frequency road noise over a long period of time. Preferably, 5.0-15.0 GPa is used.

  Preferred embodiments of the fiber type of the organic fiber cord are 1 selected from nylon 6 fiber, nylon 66 fiber, polyethylene terephthalate fiber, polyethylene naphthalate fiber, polyolefin ketone fiber, polyvinyl alcohol fiber, aramid fiber and rayon fiber. It is preferable to use one or more types. Among these, those using polyethylene naphthalate (PEN) fiber or polyolefin ketone (POK) fiber are most preferable from the viewpoint of reduction of medium frequency road noise.

  The belt cover layer made of an organic fiber cord needs to be wound so as to be present at least on the edge of the belt layer 6, but is wound so as to cover the entire area of the belt layer 6. May exist.

  FIG. 2 shows a schematic enlarged view of the vicinity of the belt edge portion, and a preferable cover region in the present invention will be described.

  The portion A in FIG. 2 shows a region between the edge portions of all the belt layers (two layers or three layers). In the present invention, it is important to cover at least this region A. .

  The position of the end portion of the belt cover layer 7 in the outer direction in the tire width direction is a belt whose edge end is located on the outermost side in the tire width direction (even the first belt 8 or the second belt 9). The belt 8 may correspond to the region B of 0 to 30 mm from the edge end to the outer side in the tire width direction.

  Further, the position of the end portion of the belt cover layer 7 in the inner side in the tire width direction is a belt whose edge end is located on the innermost side in the tire width direction (even the first belt 8 is the second belt 9). In FIG. 2, it is preferable to be in a region C of 5 mm to 30 mm from the edge end to the inner side in the tire width direction.

  However, the mode of covering is not limited to this, and the end portion of the belt cover layer 7 in the inner direction of the tire width direction reaches the opposite side beyond the center (center) portion 10 in the tire width direction, You may cover as a full cover layer covering the whole tire width direction. Of course, as shown in FIGS. 1 and 2, it may be an edge cover layer that covers the edge of the belt.

  In addition, for the 2 + 1 structure organic fiber cord, it is preferable to use two core strands having a twist number that is substantially untwisted or very sweet (for example, a twist pitch of 20 mm or more). . Since the side strands made of organic fibers are wound around the core, there is almost no problem with the focusing property of the core strands. This is because less is better.

  Although one side strand is not specifically limited, It is preferable that it is a twist pitch of 10-30 mm. Moreover, although the strand diameter of a core strand and a side strand is not specifically limited, It is preferable that it is about 0.1-0.4 mm. In addition, as for the strand diameters of the core strand and the side strand, all of them (all three core strands and two side strands) may be substantially the same, or all They may be substantially different, or may be substantially different between the core strand (two) and the side strand (one), but in general, all are the same Is practical.

  Moreover, the cord which comprises the belt layer 6 is not specifically limited, If it is used for tire belts, it can be used without a problem in particular. For example, according to various studies by the present inventors, the material of the twisted cord that constitutes the belt layer 6 is not particularly limited, but is preferably made of steel cord or organic fiber cord. In particular, a stranded wire cord having a 2 + 1 structure using three high tension type steel cords is preferable because cord separation at the edge portion of the belt layer 6 is less likely to occur.

  In the pneumatic radial tire of the present invention, the 2 + 1 structure steel cord constituting the belt layer has two core strands that have a twist number that is substantially untwisted or very sweet (for example, 20 mm). It is preferable to use one having the above-mentioned twist pitch. This is because there is no problem of convergence because the steel side wires are wound around the periphery, and in order to exert the effect based on the above-described concavo-convex structure more, it is better that there is no twist or less.

  Although one side strand is not specifically limited, It is preferable that it is a twist pitch of 10-30 mm. Moreover, although the strand diameter of a core strand and a side strand is not specifically limited, It is preferable that it is about 0.1-0.4 mm. In addition, as for the strand diameters of the core strand and the side strand, all of them (all three core strands and two side strands) may be substantially the same, or all They may be substantially different, or may be substantially different between the core strand (two) and the side strand (one), but in general, all are the same Is practical.

Examples 1 to 6, Conventional Example 1
A pneumatic radial tire having a tire size of 225 / 60R16 and a rim size of 16 × 7JJ was manufactured.

  The belt 6 has a two-layer configuration of a first belt and a second belt, and the belt cords used in each of the examples and the conventional examples except for the example 6 are all 1 × 3 × 0.28HT (high tension) Type) steel cord (a cord in which three high-strength steel strands having a diameter of 0.28 mm are twisted in a triple-twist shape), and the number of belt ends is 35 ends. In Example 6, a steel cord of 2 + 1 × 0.28HT was used, and the number of belt ends was 35 ends.

  Further, the belt edge cover 7 uses organic fiber cords having a twist structure shown in Table 1, respectively, and the weight of the organic fiber cord of the belt edge cover 7 per tire is 30 g and the belt edge cover width is 29 mm in each example. The same in the conventional example, specifically, in the arrangement shown in FIG. 2, in the tire width direction length, the A region is 5 mm, the B region side is 12 mm from the edge of the belt to the outside, and the C region. Each evaluation tire was manufactured by providing a belt cover layer with a total width of 29 mm with the side extending from the edge of the second belt to 12 mm inside.

  For each, the elastic modulus (GPa), road noise resistance, and tire durability of the organic fiber cord were evaluated by the following methods.

  The evaluation results are as shown in Table 1. It can be seen that the characteristics according to the present invention are excellent in balance between road noise resistance and tire durability.

(1) Elastic modulus (GPa) of organic fiber cord:
Disassemble the tire and collect the organic fiber cord. The cord diameter is measured and a tensile test is performed to draw a stress-strain curve. The points of 10N and 99N are connected with a straight line, and the slope of the straight line is obtained to obtain the elastic modulus (GPa).

  The measurement was performed on 20 cords, and the average value was defined as the elastic modulus (GPa) of the organic fiber cord.

(2) Road noise resistance:
After assembling the manufactured tire for evaluation, the air pressure is set to 210 kPa and the vehicle is run at a speed of 60 km / hour. The sound pressure level in each of the example products and the conventional example 1 is measured with a microphone attached to the driver's seat window side position.

  The evaluation is performed by using the reciprocal of the measured value as an evaluation standard, and is expressed as an index with one conventional product as 100. The larger the index value, the better the road noise resistance performance.

(3) Tire durability performance:
After the manufactured tire for evaluation is assembled with a rim, it is subjected to dry heat deterioration at an oxygen pressure of 350 kPa and a temperature of 70 ° C. for 14 days. After the dry heat deterioration, the filled oxygen is replaced with air, the air pressure is set to 170 kPa, and the load (= 3.5 ± 1.1 kN) and the slip angle (= 0 ± 3 °) are each sine wave fluctuation (0.03 Hz). ) And run at a speed of 60 km / hour.

  The running test was continuously carried out until the tire broke down, and it was expressed as an index with the running distance until the failure of one conventional example as 100. The larger the index value, the better the tire durability performance.

FIG. 1 is a meridian direction cross-sectional schematic view of a tire for explaining an example of an embodiment of a pneumatic radial tire of the present invention. FIG. 2 is a schematic enlarged view of the vicinity of the belt edge portion for explaining various aspects of covering the vicinity of the belt edge portion with a belt cover layer in the pneumatic radial tire of the present invention.

Explanation of symbols

1: Tread portion 2: Side wall portion 3: Bead portion 4: Carcass layer 5: Bead core 6: Belt layer 7: Belt cover layer covering both edge portions of the belt layer 8: First belt 9: Second belt 10: Tire width direction center

Claims (6)

  A pneumatic radial tire comprising a 2 + 1 structure organic fiber cord wound as a belt cover layer on at least a belt edge portion of a belt layer.   2. The pneumatic radial tire according to claim 1, wherein the organic fiber cord having a 2 + 1 structure is a high elastic modulus organic fiber cord having an elastic modulus of 4.5 to 18.0 GPa.   The organic fiber cord having a 2 + 1 structure is made of one or more kinds selected from nylon 6 fiber, nylon 66 fiber, polyethylene terephthalate fiber, polyethylene naphthalate fiber, polyolefin ketone fiber, polyvinyl alcohol fiber, aramid fiber and rayon fiber. The pneumatic radial tire according to claim 1, wherein the pneumatic radial tire is a tire.   The pneumatic radial tire according to any one of claims 1 to 3, wherein the organic fiber cord is made of polyethylene naphthalate fiber.   The pneumatic radial tire according to any one of claims 1 to 3, wherein the organic fiber cord is made of a polyolefin ketone fiber.   The pneumatic radial tire according to any one of claims 1 to 5, wherein the cord constituting the belt layer is a steel cord having a 2 + 1 structure.

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