JP2009023602A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire preventing a stud pin from easily falling out. <P>SOLUTION: A tread 1 is formed of a first rubber layer 1a and a second rubber layer 1b. The second rubber layer 1b is so formed that a 100% modulus is 2.0 MPa or more and a 300% modulus is 9.0 MPa or more. A part in a height direction including the base end of the stud pin 5 buried in the first and the second rubber layers 1a, 1b is arranged in the second rubber layer 1b. Therefore, it is possible to increase a fastening force to a pin body 5a and a flange 5c of the stud pin 5 by the second rubber layer 1b, and to improve resistance for a pin fall-out property. In this case, since the second rubber layer 1b is arranged inside the tire radial direction of the first rubber layer 1a, the first rubber layer 1a can be formed of rubber suitable for a tire surface, and there is an advantage of not deteriorating riding comfort and on-snow performance. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire used for running on snow and ice roads such as passenger cars, trucks, and buses.

2. Description of the Related Art Conventionally, as a pneumatic tire for running on snow and ice called a stud tire or a spike tire, an anti-slip stud pin embedded in a tread portion is known (see, for example, Patent Document 1).
JP 2003-267004 A

  However, in the pneumatic tire, since the stud pin is driven into the hole provided in the tread portion and attached, the stud pin may fall off due to an impact during running. There was a problem of lowering.

  The present invention has been made in view of the above problems, and an object thereof is to provide a pneumatic tire in which a stud pin does not easily fall off.

  In order to achieve the above object, the present invention provides a pneumatic tire having stud pins embedded in a tread portion, a first rubber layer disposed on the outer side in the tire radial direction of the tread portion, and a first rubber layer A second rubber layer disposed on the inner side in the tire radial direction of the tire, wherein the second rubber layer is formed so that the 100% modulus is 2.0 MPa or more and the 300% modulus is 9.0 MPa or more, and a stud pin The stud pin is embedded in the first and second rubber layers so that a part in the height direction including the base end side of the first rubber layer is disposed in the second rubber layer.

  Thereby, since the 100% modulus of the second rubber layer is 2.0 MPa or more, the fastening force from the radial direction mainly on the portion having a small outer diameter of the stud pin is increased, and 300% of the second rubber layer is increased. Since the% modulus is 9.0 MPa or more, the fastening force from the radial direction mainly on the portion having a large outer diameter of the stud pin is increased. In this case, since the second rubber layer is disposed on the inner side in the tire radial direction of the first rubber layer, the first rubber layer can be formed from rubber suitable for the tire surface side.

  According to the present invention, the second rubber layer can increase the tightening force from the radial direction to the portion with a small outer diameter and the portion with a large outer diameter of the stud pin. be able to. In this case, since the first rubber layer can be formed from rubber suitable for the tire surface side, there is an advantage that riding comfort and performance on snow are not deteriorated.

  1 to 5 show an embodiment of the present invention. FIG. 1 is a partial plan view of a pneumatic tire, FIG. 2 is a front sectional view of an essential part thereof, and FIG. 3 is an enlarged front sectional view of an essential part thereof. 4 and 5 are diagrams showing test results.

  This pneumatic tire has a tread portion 1 formed on the tire outer peripheral surface side, and the tread portion 1 is provided with a plurality of vertical grooves 2 extending in the tire circumferential direction and a plurality of horizontal grooves 3 extending in the tire width direction. It has been. Further, the tread portion 1 is provided with a block 4 defined by the vertical groove 2 and the horizontal groove 3, and a stud pin 5 is embedded in the block 4.

  The tread portion 1 includes a first rubber layer 1a disposed on the outer side in the tire radial direction and a second rubber layer 1b disposed on the inner side in the tire radial direction of the first rubber layer 1a. The layer 1b is formed of rubber having a 100% modulus of 2.0 MPa or more and a 300% modulus of 9.0 MPa or more. These modulus values are obtained by measuring the modulus at 100% and 300% elongation according to JISK6251. For the second rubber layer 1b, rubber having a compression set of 25% or less is used. The compression set here is the amount of strain after the rubber compressed to 25% of the whole is left to stand at 70 ° C. for 24 hours and the compression is released. Further, a range W within 15% of the ground contact width from the center in the tire width direction in the tread portion 1 is formed such that the thickness of the second rubber layer 1b is smaller than that of the second rubber layer 1b in other portions. ing.

  The stud pin 5 has a substantially cylindrical pin body 5a, a protrusion 5b provided on the tip surface (upper end side in the figure) of the pin body 5a, and a pin body on the base end part (lower end side in the figure) of the pin body 5a. The pin 5a has a flange 5c provided to have an outer diameter larger than that of the pin 5a. The stud pin 5 is embedded in the first and second rubber layers 1a and 1b so that the distal end portion of the pin body 5a and the protrusion 5b protrude from the first rubber layer 1a to the outside, and the proximal end side of the pin body 5a And the flange 5c is arrange | positioned in the 2nd rubber | gum layer 1b. In this case, the stud pin 5 has the first and second rubbers such that the portion disposed in the second rubber layer 1b has a height H1 of 15% or more of the total pin length H2 from the base end of the stud pin 5. It is embedded in the layers 1a and 1b.

  In the pneumatic tire configured as described above, since a part including the proximal end side of the stud pin 5 is disposed in the second rubber layer 1b, the stud pin 5 is formed of the second rubber layer 1b. Receives tightening force with rubber. In this case, since the 100% modulus of the second rubber layer 1b is 2.0 MPa or more, the fastening force from the radial direction of the stud pin 5 to the pin body 5a is mainly increased. Further, since the 300% modulus of the second rubber layer 1b is 9.0 MPa or more, the fastening force from the radial direction of the stud pin 5 to the flange 5c is mainly increased. If the 100% modulus is smaller than 2.0 MPa and the 300% modulus is smaller than 9.0 MPa, a sufficient effect of preventing pin pull-out cannot be obtained, so that the 100% modulus is 2.0 MPa or more, preferably 2. 4 MPa or more is preferable, and the 300% modulus is 9.0 MPa or more, preferably 10.0 MPa or more.

  Here, about the Examples 1-4 of this invention and the comparative example, when the test of pin pull-out-proof property, riding comfort, and the performance on snow was done, the result shown in FIG.4 and FIG.5 was obtained. Examples 1 and 2 use 100% modulus and 300% modulus different from those of the comparative example, and Examples 3 and 4 have 100% modulus, 300% modulus and compression set different from those of the comparative example. Things were used. Further, in the comparative example and the example 3, the second rubber layer 1b having a tire width direction center side thickness and a shoulder part side thickness of 4.0 mm is used. A rubber layer 1b having a thickness of 1.0 mm on the center side in the tire width direction and a thickness of 4.0 mm on the shoulder side was used. In this measurement, a stud tire having a tire size of 205 / 65R15 was mounted on a domestic car with a displacement of 2500 cc.

  In the anti-pinning resistance test, after running at a speed of 40 to 100 km / h for 1000 km, the reciprocal of the number of unpinned pins was indexed, and each of Examples 1 to 4 was evaluated using a comparative example as 100. In this case, it was evaluated that the larger the index value, the smaller the number of missing pins, and the superiority.

  In the ride comfort test, the sensory evaluation results of the driver during driving were indexed, and a comparative example was evaluated as 100, and the higher the index value, the better.

  In the on-snow performance test, a total of the driver's sensory evaluation results for snow braking performance and snow handling stability was indexed, and a comparative example was evaluated as 100, and the higher the index value, the more superior.

  As a result of the test, Examples 1 to 4 were superior to the comparative example in at least one of anti-pinning resistance, riding comfort and performance on snow.

  Thus, according to the present embodiment, the tread portion 1 is formed of the first rubber layer 1a and the second rubber layer 1b, and the second rubber layer 1b has a 100% modulus of 2.0 MPa or more and A portion of the height direction including the base end side of the stud pin 5 embedded in the first and second rubber layers 1a, 1b is formed with the 300% modulus of 9.0 MPa or more. Since it is arranged in the layer 1b, the tightening force of the stud pin 5 against the pin body 5a and the flange 5c can be increased by the second rubber layer 1b, and the anti-pinning resistance can be improved. . In this case, since the second rubber layer 1b is disposed on the inner side in the tire radial direction of the first rubber layer 1a, the first rubber layer 1a can be formed from rubber suitable for the tire surface side. There is an advantage that comfort and performance on snow are not deteriorated.

  In this case, the stud pin 5 is connected to the first and second rubber layers so that the height H1 of the portion disposed in the second rubber layer 1b is 15% or more of the total pin length H2 from the base end of the stud pin 5. Since it is embedded in 1a and 1b, the tightening force to the stud pin 5 by the second rubber layer 1b can be sufficiently obtained as compared with the case where the height H1 is smaller than 15% of the total length H2 of the pin. Further, the anti-pinning resistance can be further improved.

  In addition, since the rubber having a compression set of 25% or less is used for the second rubber layer 1b, the elastic force of the second rubber layer 1b is prevented from being lowered as compared with the case where the compression set is less than 25%. The effect can be enhanced, and the anti-pinning resistance effect can be maintained even in long-term use.

  Furthermore, in the range W within 15% of the ground contact width from the center in the tire width direction in the tread portion 1, stud pins are often not provided for asphalt road surface protection. Therefore, the second rubber layer 1b in this range W is not provided. Is made smaller than the second rubber layer 1b of the other part, and the thickness of the first rubber layer 1a is increased by that amount, thereby improving riding comfort and performance on snow. Can do. In this case, a range W within 15% of the ground contact width may be formed so that the second rubber layer 1b does not exist.

The fragmentary top view of the pneumatic tire which shows one Embodiment of this invention Front sectional view of main parts of pneumatic tire Expanded front sectional view of main parts of pneumatic tire Diagram showing test results Diagram showing test results

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Tread part, 1a ... 1st rubber layer, 1b ... 2nd rubber layer, 5 ... Stud pin.

Claims (4)

In a pneumatic tire having a stud pin embedded in a tread portion,
A first rubber layer disposed on the outer side in the tire radial direction of the tread portion;
A second rubber layer disposed on the inner side in the tire radial direction of the first rubber layer,
Forming the second rubber layer so that the 100% modulus is 2.0 MPa or more and the 300% modulus is 9.0 MPa or more;
A pneumatic tire characterized in that the stud pin is embedded in the first and second rubber layers so that a part of the height direction including the base end side of the stud pin is disposed in the second rubber layer. The stud pin is embedded in the first and second rubber layers so that the portion disposed in the second rubber layer is 15% or more of the total length of the pin from the base end of the stud pin. The pneumatic tire according to 1. When the rubber compressed to 25% of the whole is left at 70 ° C. for 24 hours, and the distortion after releasing the compression is the compression permanent distortion, the rubber whose compression permanent distortion is 25% or less is used for the second rubber layer. The pneumatic tire according to claim 1 or 2, characterized in that: The thickness of the second rubber layer is smaller than the second rubber layer of the other part or the second rubber layer does not exist within a range within 15% of the contact width from the center in the tire width direction in the tread portion. The pneumatic tire according to claim 1, 2, or 3, wherein the pneumatic tire is formed as described above.

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