JP2009119932A - Pneumatic tire and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of combining grounding performance and durability, and its production method. <P>SOLUTION: The pneumatic tire 1 includes a belt layer 4 arranged outside in the tire diameter direction of a carcass layer 3 and a tread rubber 5 arranged outside in the tire diameter direction of the belt layer 4. The tread rubber 5 is composed by laminating a cap rubber layer 51 made of a poor-conductive rubber material and composing a tread surface and a base rubber layer 52 made of high-conductive rubber material. A filament conductor 53 is arranged penetrating through the cap rubber layer 51 from an outer surface of a tread part to the base rubber layer 52 and conductively contacting the base rubber layer 52 without penetrating through the base rubber layer 52. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire and a method for manufacturing the same, and more particularly to a pneumatic tire capable of achieving both ground performance and durability performance of the tire and a method for manufacturing the same.

  In recent pneumatic tires, silica is blended in the tread rubber cap rubber layer. As a result, the rolling resistance of the tire is reduced, and the grip performance of the tire is enhanced.

  However, such a cap rubber layer has a larger electric resistance (defective conductive rubber layer) than a cap rubber layer not containing silica. For this reason, the cap rubber layer becomes an insulator, and static electricity generated in the vehicle is charged inside the tire. Therefore, in such a configuration, means for discharging the charge inside the tire to the road surface is necessary (grounding performance of the tire).

  As a conventional pneumatic tire related to this problem, a technique described in Patent Document 1 is known. Conventional pneumatic tires (pneumatic rubber tires) include two separate sidewalls and two spatially separated bead portions, and (a) a unitary rubber composition with high electrical resistivity or (b) A pneumatic rubber tire comprising a carbon black reinforced rubber carcass that supports a rubber tread that circumferentially surrounds an outer periphery that is a cap / base structure, the rubber composition of the tread cap and / or tread base being large The tread, or possibly the outer surface of the tread cap, is designed to ground, and the high electrical resistivity of the rubber composition (s) is: The tire has an electrical resistance of at least 20,000 mega-ohms as measured by the WDK110 test. The tread creates a conductive path from the outer surface of the tread to the conductive tire carcass, and thereby from about 1 ohm to about 10,000 as measured by the WDK110 test. In order to make a tire having an electrical resistance in the mega-ohm range, it is characterized by having conductive flexible filament yarns sewn through the tread.

JP 2000-127720 A

  However, in the conventional pneumatic tire, the thread conductor (conductive flexible filament thread) is sewn through the tread rubber, so that moisture on the road surface or outside air is transmitted along the thread conductor to the belt. Break into layers. For this reason, there exists a subject that the durable performance of a tire falls.

  Therefore, the present invention has been made in view of the above, and an object of the present invention is to provide a pneumatic tire that can achieve both the ground performance and the durability performance of the tire and a method for manufacturing the same.

  In order to achieve the above object, a pneumatic tire according to the present invention includes a belt layer disposed on the outer side in the tire radial direction of the carcass layer, and a tread rubber disposed on the outer side in the tire radial direction of the belt layer, and A pneumatic tire in which the tread rubber is formed by laminating a cap rubber layer made of a defective conductive rubber material and constituting a tread surface and a base rubber layer made of a good conductive rubber material, the tread portion A thread conductor is disposed that penetrates the cap rubber layer from the outer surface to the base rubber layer and contacts the base rubber layer in a conductive manner without penetrating the base rubber layer. It is characterized by.

  In this pneumatic tire, (1) Static electricity generated in the vehicle is released to the road surface through the wheel, tire bead, carcass layer, belt layer, base rubber layer (good conductive rubber layer) and yarn conductor. Is done. That is, by disposing the thread conductor on the cap rubber layer which is a defective conductive rubber layer, the charge inside the tire (base rubber layer) is discharged to the road surface via the thread conductor. Thereby, there exists an advantage by which the grounding performance of a tire is ensured appropriately. Also, (2) since the yarn conductor does not penetrate the base rubber layer, the sealing performance between the belt layer side and the cap rubber layer side is ensured by the base rubber layer. Therefore, the water on the road surface or outside air does not enter the belt layer through the yarn conductor. Thereby, there is an advantage that moisture permeation into the belt layer is prevented and the durability performance of the tire is maintained appropriately.

  In the pneumatic tire according to the present invention, the plurality of yarn conductors are arranged at a predetermined interval d in the tire circumferential direction.

  In this pneumatic tire, since a plurality of thread conductors are arranged in the tire circumferential direction, the charge inside the tire (base rubber layer) is discharged to the road surface via any of the thread conductors. Thereby, there exists an advantage by which the grounding performance of a tire is ensured appropriately.

In the pneumatic tire according to the present invention, the yarn conductor has an electric resistance of 10 ⁶ [Ω · cm] or less.

  In this pneumatic tire, since the electrical resistance of the yarn conductor is optimized, there is an advantage that the grounding function of the tire by the yarn conductor is appropriately ensured.

  In the pneumatic tire according to the present invention, the end portion on the inner side in the tire radial direction of the yarn conductor is inserted into the base rubber layer.

  In this pneumatic tire, when a tread rubber is formed by laminating a cap rubber layer and a base rubber layer, a thread conductor is subsequently inserted (sewn) into the tread rubber. it can. Thereby, there exists an advantage which can ensure appropriately conduction | electrical_connection with the base rubber layer 52 and the thread conductor 53 by a simple manufacturing process.

  In the pneumatic tire according to the present invention, the end portion on the inner side in the tire radial direction of the yarn conductor is disposed between the cap rubber layer and the base rubber layer.

  In this pneumatic tire, the separation of the base rubber layer starting from the yarn conductor is reduced compared to a configuration in which the yarn conductor is inserted into the base rubber layer. Thereby, there exists an advantage by which the sealing performance of the belt layer side and the cap rubber layer side is appropriately maintained by the base rubber layer.

  In the pneumatic tire according to the present invention, a sub yarn conductor is disposed between the cap rubber layer and the base rubber layer, and the sub yarn conductor and the yarn conductor are engaged with each other. Arranged.

  In this pneumatic tire, conduction between the yarn conductor and the base rubber layer is appropriately ensured through the sub-yarn conductor. Thereby, there exists an advantage by which the grounding performance of a tire is ensured appropriately.

  Further, the tire manufacturing method according to the present invention is a tire manufacturing method including a step of sewing a thread conductor into unvulcanized tread rubber, and the sewing needle for sewing the thread conductor is exceeded. The yarn conductor is sewn into the tread rubber while being sonic-vibrated.

  In this tire manufacturing method, the resistance of the tread rubber is reduced by the ultrasonic vibration of the sewing needle, and the sewing needle is easily inserted into the tread rubber. Thereby, there exists an advantage by which the sewing process of a thread conductor is made easy.

  In the tire manufacturing method according to the present invention, the tip of the sewing needle has a knife shape.

  In this tire manufacturing method, the entry resistance of the sewing needle to the tread rubber is reduced, so that the yarn conductor is more easily sewn into the tread rubber. Thereby, there exists an advantage by which the sewing process of a thread conductor is made easy.

  Further, the tire manufacturing method according to the present invention includes a step of providing a notch at a stitching position of the yarn conductor prior to the stitching step of the yarn conductor.

  In this tire manufacturing method, a notch is provided at a predetermined position of the tread rubber (a thread conductor sewing position), and the thread conductor is sewn along the notch. Therefore, the entry resistance of the sewing needle to the tread rubber is reduced as compared with the configuration in which the thread conductor is sewn to the tread rubber not provided with the cut. Thereby, there exists an advantage by which the sewing process of a thread conductor is made easy.

  In the tire manufacturing method according to the present invention, the plurality of yarn conductors are sewn in the tire circumferential direction with respect to the tread rubber while changing the arrangement interval d.

  In this tire manufacturing method, the sewing position of the thread conductor can be appropriately changed according to the tread design and the like. Thereby, there exists an advantage by which the earth effect by a thread conductor is ensured appropriately, and there exists an advantage by which the vulcanization failure of a tire is reduced.

  In the tire manufacturing method according to the present invention, when the tread rubber includes a cap rubber layer constituting a tread surface and a base rubber layer laminated on the cap rubber layer, the laminated cap rubber layer and the The thread conductor is sewn into the base rubber layer.

  In this tire manufacturing method, for example, the tread rubber molding process is facilitated as compared with a configuration in which the cap rubber layer and the base rubber layer are laminated after the thread conductor is sewn into the cap rubber layer. There are advantages to being.

  Further, in the tire manufacturing method according to the present invention, when the tread rubber includes a cap rubber layer constituting a tread surface and a base rubber layer laminated on the cap rubber layer, the yarn conductor is the cap rubber. After being sewn into the layers, the cap rubber layer and the base rubber layer are laminated.

  In this tire manufacturing method, for example, in a configuration in which the thread conductor is sewn only into the cap rubber layer, there is an advantage that the threading process of the thread conductor is made efficient.

  In the pneumatic tire according to the present invention, (1) static electricity generated in the vehicle passes through the wheel, the bead portion of the tire, the carcass layer, the belt layer, the base rubber layer (good conductive rubber layer), and the yarn conductor. Released on the road surface. That is, by disposing the thread conductor on the cap rubber layer which is a defective conductive rubber layer, the charge inside the tire (base rubber layer) is discharged to the road surface via the thread conductor. Thereby, there exists an advantage by which the grounding performance of a tire is ensured appropriately. Also, (2) since the yarn conductor does not penetrate the base rubber layer, the sealing performance between the belt layer side and the cap rubber layer side is ensured by the base rubber layer. Therefore, the water on the road surface or outside air does not enter the belt layer through the yarn conductor. Thereby, there is an advantage that moisture permeation into the belt layer is prevented and the durability performance of the tire is maintained appropriately.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Further, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

  FIG. 1 is a sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment of the present invention. 2 and 3 are explanatory views showing the cap tread rubber of the pneumatic tire shown in FIG. 4-8 is explanatory drawing which shows the modification of the pneumatic tire described in FIG. 9 and 10 are explanatory views showing a method for manufacturing the pneumatic tire shown in FIG. FIG. 11 is an explanatory view showing a modification of the method for manufacturing the pneumatic tire shown in FIG. 9. FIG. 12 is a chart showing the results of the performance test of the pneumatic tire according to the example of the present invention. FIG. 13 is a chart showing the composition of the cap rubber layer and the base rubber layer.

[Pneumatic tire]
The pneumatic tire 1 includes a bead core (not shown), a carcass layer 3, a belt layer 4, a tread rubber 5, and a sidewall rubber 6 (see FIG. 1). The bead core 2 has an annular structure and is configured as a pair of left and right. The carcass layer 3 is bridged in a toroidal shape between the left and right bead cores 2 and 2 to constitute a tire skeleton. The belt layer 4 includes a plurality of stacked belt members 41 to 43 and is disposed on the outer periphery in the tire radial direction of the carcass layer 3. The tread rubber 5 is disposed on the outer circumference in the tire radial direction of the carcass layer 3 and the belt layer 4 to constitute a tread portion of the tire. The sidewall rubber 6 is disposed on the outer side in the tire width direction of the carcass layer 3 to constitute a sidewall portion of the tire.

The tread rubber 5 is configured by laminating a cap rubber layer 51 and a base rubber layer 52 (see FIGS. 1 and 2). The cap rubber layer 51 constitutes a tread surface of the tire. The base rubber layer 52 is laminated and disposed on the inner side in the tire radial direction of the cap rubber layer 51. Further, the cap rubber layer 51 is made of a defective conductive rubber material, and the base rubber layer 52 is made of a good conductive rubber material (see FIG. 13). Here, the defective conductive rubber material means a rubber material having a resistance value larger than 10 ⁸ [Ω · cm]. The highly conductive rubber material means a rubber material having a resistance value of 10 ⁸ [Ω · cm] or less.

For example, in this embodiment, the tread rubber 5 has a two-layer structure including a cap rubber layer 51 and a base rubber layer 52 (see FIGS. 1 and 2). The tread rubber 5 is disposed on the outer side in the tire radial direction of the belt layer 4 with the surface on the cap rubber layer 51 side facing the outer side in the tire radial direction. For this reason, the base rubber layer 52 is located between the cap rubber layer 51 and the belt layer 4. The cap rubber layer 51 forms a tread surface (the outer surface of the tread portion). Further, the cap rubber layer 51 is made of a rubber material in which a large amount of silica is blended. On the other hand, the base rubber layer 52 is made of a rubber material not containing silica. For this reason, the cap rubber layer 51 has low conductivity (defective conductive rubber layer), and the base rubber layer 52 has high conductivity (good conductive rubber layer). For example, in the configuration shown in FIG. 13, the resistance value of the cap rubber layer 51 is 10 ¹⁴ [Ω · cm], and the resistance value of the base rubber layer 52 is 10 ⁷ [Ω · cm].

[Thread conductor]
Here, in this pneumatic tire 1, the thread conductor 53 is arrange | positioned at the tread rubber 5 (refer FIGS. 1-3). This thread conductor 53 penetrates through the cap rubber layer 51 from the outer surface of the tread portion to the base rubber layer 52. Further, the thread conductor 53 contacts the base rubber layer 52 in a conductive manner without penetrating the base rubber layer 52. Specifically, the end portion of the yarn conductor 53 is disposed in contact with or inserted into the base rubber layer 52.

  For example, in this embodiment, the yarn conductor 53 is disposed on the tread rubber 5 (see FIGS. 1 to 3). This thread conductor 53 penetrates through the cap rubber layer 51 from the outer surface of the tread portion (tire contact surface of the tire) to the base rubber layer 52. Further, the yarn conductor 53 is arranged with its end portion inserted (pierced) into the base rubber layer 52. Thereby, the thread conductor 53 is in contact with the base rubber layer 52 so as to be conductive. Further, the yarn conductor 53 does not penetrate the base rubber layer 52.

  The yarn conductor 53 may be a member containing a conductive material such as carbon fiber, or may be a member covered with such a conductive material. The yarn conductor 53 may be a twisted multifilament or a monofilament. In this embodiment, the diameter of the yarn conductor 53 is set to 0.5 [mm].

[effect]
In this pneumatic tire 1, (1) the static electricity generated in the vehicle causes the wheel, the bead portion of the tire, the carcass layer 3, the belt layer 4, the base rubber layer 52 (good conductive rubber layer) and the yarn conductor 53. To the road surface. That is, by disposing the thread conductor 53 on the cap rubber layer 51 which is a defective conductive rubber layer, the charge inside the tire (base rubber layer 52) is discharged to the road surface via the thread conductor 53. The Thereby, there exists an advantage by which the grounding performance of a tire is ensured appropriately. (2) Since the yarn conductor 53 does not penetrate the base rubber layer 52, the base rubber layer 52 ensures the sealing performance between the belt layer 4 side and the cap rubber layer 51 side. Therefore, the water on the road surface or outside air does not enter the belt layer through the yarn conductor. Thereby, there is an advantage that moisture permeation into the belt layer 4 is prevented and the durability performance of the tire is maintained appropriately.

[Additional matter 1]
In the pneumatic tire 1, it is preferable that the plurality of yarn conductors 53 are arranged at a predetermined interval d in the tire circumferential direction (see FIG. 3). That is, a plurality of yarn conductors 53 are provided on the tread rubber 5, and these yarn conductors 53 are intermittently arranged in the tire circumferential direction. In such a configuration, since the plurality of yarn conductors 53 are arranged in the tire circumferential direction, the charge inside the tire (base rubber layer 52) is discharged to the road surface via any one of the yarn conductors 53. Thereby, there exists an advantage by which the grounding performance of a tire is ensured appropriately.

  Specifically, the arrangement interval d of the yarn conductors 53 is preferably shorter than the tire contact length, and more preferably shorter than 1/3 of the tire contact length. In such a configuration, one of the yarn conductors 53 is grounded to the road surface when the tire rolls. Thereby, there exists an advantage by which the grounding performance of a tire is ensured appropriately.

  Moreover, it is preferable that the arrangement interval d of the yarn conductors 53 is appropriately defined by the relationship with the position of lug grooves (not shown) formed on the tread surface. Specifically, the arrangement interval d of the yarn conductors 53 is defined so that the lug grooves and the yarn conductors 53 are arranged at different positions. Thereby, there exists an advantage by which the earthing | grounding function of the tire by the thread conductor 53 is ensured appropriately, and there exists an advantage by which the vulcanization failure of a tire is reduced. Note that the stitching position of the yarn conductor 53 in the tire width direction can be appropriately set according to the tread design of the tire.

  Further, the end of the yarn conductor 53 on the outer side in the tire radial direction may be positioned on the tread surface (on the outer surface of the cap rubber layer 51) (see FIG. 3), or from the tread surface. You may protrude (refer FIG. 4).

In the pneumatic tire 1, the electrical resistance of the yarn conductor 53 is preferably 10 ⁶ [Ω · cm] or less. In such a configuration, since the electrical resistance of the yarn conductor 53 is optimized, there is an advantage that the tire grounding function by the yarn conductor 53 is appropriately ensured. For example, if the electrical resistance of the yarn conductor exceeds 10 ⁶ [Ω · cm], the grounding function of the tire becomes insufficient.

[Additional matter 2]
Further, in the pneumatic tire 1, it is preferable that the end portion on the inner side in the tire radial direction of the yarn conductor 53 is inserted into the base rubber layer 52 (see FIGS. 2 and 3). In such a configuration, when the tread rubber 5 is formed by laminating the cap rubber layer 51 and the base rubber layer 52, the thread conductor 53 is subsequently inserted (sewn) into the tread rubber 5. Can be placed. Thereby, there exists an advantage which can ensure appropriately conduction | electrical_connection with the base rubber layer 52 and the thread conductor 53 by a simple manufacturing process.

  For example, in this embodiment, the tread rubber 5 including the cap rubber layer 51 and the base rubber layer 52 is molded by two-color extrusion molding (see FIGS. 1 to 3). A plurality of yarn conductors 53 are inserted into the base rubber layer 52 and disposed. Further, the yarn conductor 53 is vertically and linearly inserted into the outer surface of the tread portion. Further, the thread conductor 53 penetrates the cap rubber layer 51 and is inserted into the base rubber layer 52. Thereby, the electrical connection between the yarn conductor 53 and the base rubber layer 52 is ensured appropriately. Further, since the yarn conductor 53 does not penetrate the base rubber layer 52, the sealing performance between the belt layer 4 side and the cap rubber layer 51 side is ensured by the base rubber layer 52.

  In this embodiment, the thickness T of the tread rubber 5 is in the range of 7 [mm] to 12 [mm], and the thickness t of the base rubber layer 52 is 1 [mm] to 3.5 [mm]. (See FIG. 2). Further, the embedment depth h of the yarn conductor 53 with respect to the base rubber layer 52 is in the range of 0 <h <t.

  However, the present invention is not limited thereto, and the end portion on the inner side in the tire radial direction of the yarn conductor 53 may be disposed between the cap rubber layer 51 and the base rubber layer 52 (boundary surface) (see FIG. 5). ). In such a configuration, the separation of the base rubber layer starting from the yarn conductor is reduced as compared with a configuration in which the yarn conductor is inserted into the base rubber layer. Thereby, there is an advantage that the sealing property between the belt layer 4 side and the cap rubber layer 51 side is properly maintained by the base rubber layer 52.

  For example, in this embodiment, the thread conductor 53 is vertically and linearly inserted into the outer surface of the tread portion and penetrates the cap rubber layer 51 (see FIG. 5). Further, the end portion of the yarn conductor 53 is bent on the inner surface side (base rubber layer 52 side) of the cap rubber layer 51. The bent end is sandwiched between the cap rubber layer 51 and the base rubber layer 52. Thereby, the electrical connection between the yarn conductor 53 and the base rubber layer 52 is ensured appropriately. Further, the sealing property between the belt layer 4 side and the cap rubber layer 51 side is ensured by the base rubber layer 52.

[Additional matter 3]
In the pneumatic tire 1, the sub-yarn conductor 54 is disposed between the cap rubber layer 51 and the base rubber layer 52, and the sub-yarn conductor 54 and the above-described yarn conductor 53 are engaged. It is preferable to arrange them together (see FIGS. 6 to 8). In such a configuration, the electrical connection between the yarn conductor 53 and the base rubber layer 52 is appropriately ensured through the sub-yarn conductor 54. Thereby, there exists an advantage by which the grounding performance of a tire is ensured appropriately.

  For example, in this embodiment, a thread-like sub-thread conductor 54 is disposed on the inner surface side (base rubber layer 52 side) of the cap rubber layer 51 (see FIGS. 6 and 7). The yarn conductor 53 passes through the cap rubber layer 51 from the outer surface of the tread portion, and the yarn conductor 53 and the sub yarn conductor 54 are engaged on the inner surface side of the cap rubber layer 51. is doing. Further, the sub-yarn conductor 54 is sandwiched between the cap rubber layer 51 and the base rubber layer 52. Thereby, the electrical connection between the yarn conductor 53 and the base rubber layer 52 is ensured appropriately.

  In the above-described configuration, the engaging portion between the yarn conductor 53 and the sub-yarn conductor 54 is on the inner side surface of the cap rubber layer 51 (on the boundary surface between the cap rubber layer 51 and the base rubber layer 52). It may be located (see FIG. 7) or may be located inside the cap rubber layer 51 (see FIG. 8).

[Tire manufacturing method]
In general, in the step of sewing the thread conductor into the unvulcanized tread rubber, there is a problem that the resistance of the tread rubber is large, so that a sewing needle for sewing the thread conductor hardly enters the tread rubber. For example, even if the sewing needle is pressed against a tread rubber having a thickness of 10 mm and unvulcanized, the sewing needle does not easily stick into the tread rubber.

  Therefore, the pneumatic tire 1 is preferably manufactured by the following tire manufacturing apparatus 10 and tire manufacturing method (see FIGS. 9 and 10). First, the tire manufacturing apparatus 10 has a sewing needle 11 for sewing the thread conductor 53 into the tread rubber 5, driving means 12 for driving the sewing needle 11 in the vertical direction (axial direction), and the sewing needle 11. And ultrasonic oscillation means 13 for ultrasonic vibration. In addition, the ultrasonic oscillation means 13 can ultrasonically vibrate the sewing needle 11 at a frequency of 10 [Hz] to 100 [Hz], for example.

  In the tire manufacturing method, first, the cap rubber layer 51 and the base rubber layer 52 of the tread rubber 5 are formed by two-color extrusion molding (see FIG. 9). The tread rubber 5 is an unvulcanized rubber having a band shape. Next, the thread conductor 53 is sewn into the tread rubber 5. Specifically, the thread conductor 53 is sewn into the tread rubber 5 by the drive means 12 displacing the sewing needle 11 in the vertical direction. In addition, the conveying device (not shown) sequentially slides the tread rubber 5 in the tire circumferential direction, so that the plurality of yarn conductors 53 are sequentially sewn into the tread rubber 5 with a predetermined interval d in the tire circumferential direction. It is.

  At this time, the ultrasonic oscillator 13 vibrates the sewing needle 11 ultrasonically. That is, the thread conductor 53 is sewn into the tread rubber 5 when the sewing needle 11 is displaced in the vertical direction while ultrasonically vibrating. In such a configuration, the resistance of the tread rubber 5 is reduced by the ultrasonic vibration of the sewing needle 11, and the sewing needle 11 is easily inserted into the tread rubber 5. Thereby, there exists an advantage by which the sewing process of the thread conductor 53 is facilitated.

  Moreover, in said structure, it is preferable that the front-end | tip of the sewing needle 11 has a knife shape (refer FIG. 11). In such a configuration, the entry resistance of the sewing needle 11 to the tread rubber 5 is reduced, so that the thread conductor 53 is more easily sewn into the tread rubber 5. Thereby, there exists an advantage by which the sewing process of the thread conductor 53 is facilitated.

  Further, in the above configuration, it is preferable that a step of providing a notch at the sewing position of the thread conductor 53 is provided prior to the step of sewing the thread conductor 53 (not shown). In such a configuration, a notch is provided at a predetermined position of the tread rubber 5 (a stitching position of the thread conductor 53), and the thread conductor 53 is sewn along the notch. Therefore, the entry resistance of the sewing needle 11 to the tread rubber 5 is reduced as compared with the configuration in which the thread conductor is sewn to the tread rubber not provided with the cut. Thereby, there exists an advantage by which the sewing process of the thread conductor 53 is facilitated. Further, there is an advantage that the sewing process of the thread conductor 53 is speeded up. Further, there is an advantage that damage to the sewing needle 11, damage to the thread conductor 53, rubber clogging, and the like due to problems during sewing are reduced.

  For example, in this embodiment, an ultrasonic cutter may be employed as means for providing a cut in the tread rubber 5 (not shown). And this ultrasonic cutter is arrange | positioned ahead of the sewing needle 11, and cuts in the predetermined position of the tread rubber 5 in response to the operation | movement of the sewing needle 11. FIG. Then, the thread conductor 53 is sewn along the cut position. Thereby, the sewing process of the thread conductor 53 can be facilitated.

  Moreover, in said structure, it is preferable that the some thread conductor 53 is sewn on the tread rubber 5 in the tire circumferential direction, changing arrangement | positioning space | interval d (refer FIG. 9). That is, it is preferable that the sewing interval d of the thread conductor 53 can be changed. In such a configuration, the sewing position of the thread conductor 53 can be appropriately changed according to the tread design or the like. Thereby, there exists an advantage by which the earth effect by the thread conductor 53 is ensured appropriately, and there exists an advantage by which the vulcanization failure of a tire is reduced. For example, in a configuration in which the thread conductors are sewn at equal intervals, the thread conductors may be arranged at the positions of the lug grooves. Then, there is a possibility that the grounding effect of the yarn conductor cannot be obtained properly, and a tire vulcanization failure may occur.

  In the above configuration, when the tread rubber 5 includes the cap rubber layer 51 constituting the tread surface and the base rubber layer 52 laminated on the cap rubber layer 51, the laminated cap rubber layer 51 and the base rubber are laminated. The thread conductor 53 is preferably sewn into the layer 52 (see FIG. 9). That is, the thread conductor 53 is sewn into the already laminated cap rubber layer 51 and base rubber layer 52. In such a configuration, for example, the molding process of the tread rubber 5 is facilitated as compared with a configuration in which the cap rubber layer and the base rubber layer are laminated after the thread conductor is sewn into the cap rubber layer. There are advantages. Specifically, the tread rubber 5 can be molded at a time by two-color extrusion molding or the like. Further, in such a configuration, in a configuration in which one thread conductor 53 is sewn over both the cap rubber layer 51 and the base rubber layer 52 (see FIG. 2), the stitching process of the thread conductor 53 is efficient. There is an advantage that

  However, the present invention is not limited thereto, and the tread rubber 5 may be formed by laminating the cap rubber layer 51 and the base rubber layer 52 after the thread conductor 53 is sewn into the cap rubber layer 51 (not shown). ). In such a configuration, for example, in the configuration in which the thread conductor 53 is sewn only into the cap rubber layer 51 (see FIGS. 5 and 6), there is an advantage that the sewing process of the thread conductor 53 is made efficient. Note that the cap rubber layer 51 and the base rubber layer 52 can be easily bonded together before vulcanization.

[performance test]
In this example, performance tests on (1) ground performance and (2) durability performance were performed on a plurality of pneumatic tires having different conditions (see FIG. 12). In this performance test, a pneumatic tire (summer tire) having a tire size of 195 / 70R15 is assembled to an applicable rim specified by JATMA, and an internal pressure of 200 [kPa] and a load of 4.9 [kN] are applied to the pneumatic tire. Is done.

  (1) In the performance test relating to the earth performance, an electrical resistance measurement based on the JATMA test method is performed. In this performance test, the test tire is placed vertically on the steel plate and grounded, and the electrical resistance between the rim center and the steel plate is measured. At this time, a resistance measuring device having an applied voltage of 500 [V] is used. The room temperature during the performance test is 23 [° C.] and the humidity is 52 [%].

  (2) In performance tests related to durability performance, the speed reached at the time of failure is measured by increasing the speed by 8 [km / h] every 30 minutes based on the conditions specified in the high-speed performance test B of JIS D4230. Is done. Then, based on the measurement result, index evaluation using the conventional example as a reference (100) is performed. This evaluation is more preferable as the numerical value is higher.

  In the pneumatic tires of Conventional Examples 1 and 2 and Invention Examples, the cap rubber layer is made of a defective conductive rubber material, and the base rubber layer is made of a good conductive rubber material (see FIG. 13). Further, the pneumatic tire of Conventional Example 1 does not have a ground conductor for grounding (not shown). On the other hand, the pneumatic tire of Conventional Example 2 has a thread conductor for grounding (not shown). The yarn conductor is disposed through the cap rubber layer and the base rubber layer. Moreover, the pneumatic tire 1 of the invention example has a thread conductor 53 for grounding (see FIGS. 1 to 3). The yarn conductor 53 is disposed so as to penetrate only the cap rubber layer 51.

  As shown in the test results, in the pneumatic tire 1 of the inventive example, the electrical resistance is reduced as compared with the pneumatic tire of the conventional example 1, and the grounding action by the yarn conductor 53 is properly maintained. (See FIG. 12). Moreover, it turns out that the durability performance of a tire is improving compared with the pneumatic tire of the prior art example 2.

  As described above, the pneumatic tire and the manufacturing method thereof according to the present invention are useful in that both the ground performance and the durability performance of the tire can be achieved.

It is sectional drawing of the tire meridian direction which shows the pneumatic tire concerning the Example of this invention. It is explanatory drawing which shows the cap tread rubber of the pneumatic tire described in FIG. It is explanatory drawing which shows the cap tread rubber of the pneumatic tire described in FIG. It is explanatory drawing which shows the modification of the pneumatic tire described in FIG. It is explanatory drawing which shows the modification of the pneumatic tire described in FIG. It is explanatory drawing which shows the modification of the pneumatic tire described in FIG. It is explanatory drawing which shows the modification of the pneumatic tire described in FIG. It is explanatory drawing which shows the modification of the pneumatic tire described in FIG. It is explanatory drawing which shows the manufacturing method of the pneumatic tire described in FIG. It is explanatory drawing which shows the manufacturing method of the pneumatic tire described in FIG. It is explanatory drawing which shows the modification of the manufacturing method of the pneumatic tire described in FIG. It is a graph which shows the result of the performance test of the pneumatic tire concerning the Example of this invention. It is a graph which shows the composition of a cap rubber layer and a base rubber layer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Bead core 3 Carcass layer 4 Belt layers 41-43 Belt material 5 Tread rubber 51 Cap rubber layer 52 Base rubber layer 53 Thread conductor 54 Sub thread conductor 6 Side wall rubber 10 Tire manufacturing apparatus 11 Sewing needle 12 Driving means 13 Ultrasonic oscillation means

Claims (12)

A cap rubber comprising a belt layer disposed on the outer side in the tire radial direction of the carcass layer and a tread rubber disposed on the outer side in the tire radial direction of the belt layer, and made of a defective conductive rubber material and constituting a tread surface A pneumatic tire in which the tread rubber is configured by laminating a layer and a base rubber layer made of a highly conductive rubber material,
A yarn conductor is disposed from the outer surface of the tread portion through the cap rubber layer to the base rubber layer, and in contact with the base rubber layer without conducting the base rubber layer. A pneumatic tire characterized by that.   The pneumatic tire according to claim 1, wherein the plurality of yarn conductors are arranged at a predetermined interval d in the tire circumferential direction. 3. The pneumatic tire according to claim 1, wherein the yarn conductor has an electric resistance of 10 ⁶ [Ω · cm] or less.   The pneumatic tire according to any one of claims 1 to 3, wherein an end portion in the tire radial direction of the yarn conductor is inserted into the base rubber layer.   The pneumatic tire according to any one of claims 1 to 3, wherein an end portion of the yarn conductor on the inner side in the tire radial direction is sandwiched and disposed between the cap rubber layer and the base rubber layer.   The sub yarn conductor is arranged between the cap rubber layer and the base rubber layer, and the sub yarn conductor and the yarn conductor are arranged to be engaged with each other. A pneumatic tire according to any one of the above. A tire manufacturing method including a step of sewing a yarn conductor into unvulcanized tread rubber,
A tire manufacturing method, wherein the thread conductor is sewn into the tread rubber while a sewing needle for sewing the thread conductor is ultrasonically vibrated.   The tire manufacturing method according to claim 7, wherein a tip of the sewing needle has a knife shape.   9. The tire manufacturing method according to claim 7, further comprising a step of providing a notch at a sewing position of the yarn conductor prior to the step of sewing the yarn conductor.   The tire manufacturing method according to any one of claims 7 to 9, wherein the plurality of yarn conductors are sewn in the tire circumferential direction with respect to the tread rubber while changing the arrangement interval d.   When the tread rubber is composed of a cap rubber layer constituting a tread surface and a base rubber layer laminated on the cap rubber layer, the thread conductor is laminated on the laminated cap rubber layer and the base rubber layer. The tire manufacturing method according to any one of claims 7 to 10, wherein is sewn.   When the tread rubber comprises a cap rubber layer constituting a tread surface and a base rubber layer laminated on the cap rubber layer, the cap rubber layer after the thread conductor is sewn into the cap rubber layer The tire manufacturing method according to claim 7, wherein the base rubber layer and the base rubber layer are laminated.

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