JP2009023152A - Manufacturing process of pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing process of a pneumatic tire by which tread rubber having an electroconductive layer can be stably formed by a strip build construction method, volume of the electroconductive layer can be suppressed and improvement effect by using the electrically nonconductive tread rubber can be fully demonstrated. <P>SOLUTION: In the manufacturing process of the pneumatic tire including a process of forming the tread tire by winding a rubber strip along a tire peripheral direction, a cross section of the rubber strip 1 is partitioned to two or more domains including an electrically nonconductive domain 1a formed of electrically nonconductive rubber and an electroconductive domain 1b formed of electroconductive rubber by penetrating the rubber strip 1 in a thickness direction. When the rubber strip 1 is wound along the tire peripheral direction, the rubber strip 1 is laminated so that the electroconductive domains 1b are superposed in the thickness direction and the electroconductive layer 5 extending from a tread surface to a tread bottom surface is provided by the electroconductive domains 1b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a pneumatic tire in which an electrical resistance measure is taken by providing a conductive layer on a tread rubber, and more specifically includes a step of forming a tread rubber by winding a rubber strip along the tire circumferential direction. The present invention relates to a method for manufacturing a pneumatic tire.

  Conventionally, pneumatic tires with high tread rubber silica content have been known for the purpose of reducing rolling resistance, which is closely related to lower fuel consumption of vehicles, and improving braking performance (WET braking performance) on wet road surfaces. ing. However, tread rubber with high silica content has higher electrical resistance than conventional tread rubber with high carbon black content, which prevents the discharge of static electricity generated in vehicles to the road surface, resulting in problems such as radio noise. There was a problem that it was easy.

  In view of this, a pneumatic tire has been developed in which an electrical resistance measure is taken by providing a conductive layer made of a conductive rubber compounded with carbon black or the like on a non-conductive tread rubber compounded with silica or the like. For example, in the pneumatic tire described in Patent Document 1 below, a conductive layer that penetrates the tread rubber in the tire radial direction is provided, and static electricity generated in the vehicle is discharged to the road surface through this conductive layer. .

  By the way, as a method for forming the tread rubber, a so-called strip build method is known in which a tape-shaped rubber strip having a small width and a small thickness is wound and laminated in the tire circumferential direction to obtain a desired cross-sectional shape. According to this strip build method, a tread rubber is formed because a joint portion is not formed as in a case where rubber extrudates having a predetermined cross-sectional shape cut in a constant size are connected in a ring shape, and distortion and shrinkage are reduced. The uniformity of the tire can be improved by improving the formation accuracy of the tire.

  In the following Patent Documents 2 and 3, when the tread rubber is formed by the strip build method, a rubber strip in which a part or all of the outer surface of the non-conductive rubber is covered with the conductive rubber is used. A method is described in which a conductive layer is provided in the shape of a lottery or a net over almost the entire area. However, in this method, the volume of the conductive layer becomes larger than necessary, and the improvement effect by using non-conductive tread rubber, that is, fuel consumption performance and WET braking when the tread rubber is highly compounded with silica. There is a problem that the performance improvement effect is not fully exhibited.

Further, in Patent Document 4 below, a conductive layer is provided by winding and laminating a single rubber strip made of conductive rubber, and the portions other than the conductive layer are non-conductive separately from the rubber strip. A method of forming with rubber is described. However, in such a method, since the rubber strip for providing the conductive layer is small, the shape easily collapses and is unstable when it is wound and stacked several times, and peeling between the conductive rubber and the non-conductive rubber also occurs. Concerned. In addition, if the width of the rubber strip is increased to improve this, the volume of the conductive layer becomes larger than necessary, so that the improvement effect by using non-conductive tread rubber is not sufficiently exhibited.
JP-A-8-34204 JP-A-11-227415 JP 2007-8388 A JP 2002-96402 A

  The present invention has been made in view of the above circumstances, and its purpose is to stably form a tread rubber having a conductive layer by a strip build method, and to suppress the volume of the conductive layer, thereby preventing non-conductivity. An object of the present invention is to provide a method of manufacturing a pneumatic tire that can sufficiently exhibit the improvement effect of using tread rubber.

  The above object can be achieved by the present invention as described below. That is, the pneumatic tire manufacturing method according to the present invention is a pneumatic tire manufacturing method including a step of forming a tread rubber by winding a rubber strip along a tire circumferential direction. The rubber strip is partitioned into a plurality of regions including a non-conductive region formed of conductive rubber and a conductive region formed of conductive rubber that penetrates the rubber strip in the thickness direction. When winding along the tire circumferential direction, the rubber strip is laminated so that the conductive region overlaps in the thickness direction, and a conductive layer extending from the tread surface toward the tread bottom surface is provided by the conductive region.

  The method for manufacturing a pneumatic tire according to the present invention includes a step of forming a tread rubber by winding a rubber strip along the tire circumferential direction, and the tread rubber is formed by a strip build method. The tread rubber is formed using a rubber strip including a non-conductive region, and an improvement effect corresponding to the physical properties of the non-conductive rubber forming the non-conductive region is given. That is, when the non-conductive rubber has a high silica content, excellent fuel efficiency and WET braking performance are exhibited thereby.

  In the present invention, when the rubber strip is wound along the tire circumferential direction, the conductive layer is provided by laminating the rubber strip so that the conductive regions overlap in the thickness direction. The rubber strip has a cross section divided into a plurality of regions including a non-conductive region and a conductive region, and the conductive region is partially arranged at the center or end of the rubber strip. Therefore, the size of the conductive region can be reduced while securing the width dimension of the rubber strip, and the rubber strip can be stably formed even when the rubber strip is wound and stacked several times to provide the conductive layer. In addition, there is no fear of peeling between the conductive rubber and the non-conductive rubber, and the improvement effect by using the non-conductive tread rubber can be sufficiently exhibited by suppressing the volume of the conductive layer.

  In the above, the rubber strip has a non-conductive section where the conductive area is replaced with the non-conductive area in at least a part of the longitudinal direction, and when the rubber strip is wound along the tire circumferential direction, It is preferable that the rubber strips are laminated so that the nonconductive section overlaps in the thickness direction at the non-arranged portion of the conductive layer.

  According to this configuration, the rubber strip used for arranging the conductive layer is wound around the non-placed portion of the conductive layer without using different rubber strips at the place where the conductive layer is placed and the place where the conductive layer is not placed. Therefore, various winding paths can be adopted, and the tread rubber can be formed more stably. Moreover, in the non-arrangement | positioning location of a conductive layer, since the non-conductive area where the conductive area replaced the non-conductive area is overlapped, the volume of the conductive rubber is reduced and the non-conductive tread rubber is used. The improvement effect can be exhibited sufficiently.

  In the above, using a rubber strip molding apparatus capable of molding the rubber strip by co-extrusion of non-conductive rubber and conductive rubber, and a rotating support body around which the rubber strip supplied from the rubber strip molding apparatus is wound Then, when the rubber strip is wound on the rotating support member along the tire circumferential direction, the rubber strip is laminated so that the conductive region overlaps in the thickness direction at the place where the conductive layer is disposed, In the non-arranged portion of the layer, extrusion of the conductive rubber is stopped to form a non-conductive section in which the conductive area is replaced with the non-conductive area, and the rubber strip is formed so that the non-conductive section overlaps in the thickness direction. Those that are laminated are preferred.

  According to this configuration, the rubber strip used for arranging the conductive layer is wound around the non-placed portion of the conductive layer without using different rubber strips at the place where the conductive layer is placed and the place where the conductive layer is not placed. be able to. For this reason, various winding paths can be adopted, and the tread rubber can be formed more stably, and the working efficiency can be improved by continuous molding without interrupting the extrusion of the rubber strip. Moreover, in the non-arrangement | positioning location of a conductive layer, since the non-conductive area where the conductive area replaced the non-conductive area is overlapped, the volume of the conductive rubber is reduced and the non-conductive tread rubber is used. The improvement effect can be exhibited sufficiently.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, since the manufacturing method of the pneumatic tire which concerns on this invention can be performed like the conventional tire manufacturing process except the process of forming a tread rubber, it demonstrates centering on the formation process of a tread rubber. In the present invention, the tread rubber is formed by the strip build method, that is, by winding the rubber strip along the tire circumferential direction.

  FIG. 1 is a cross-sectional view showing an example of a rubber strip used in the present invention. The cross section of the rubber strip 1 is divided into a non-conductive region 1a formed of non-conductive rubber and a conductive region 1b formed of conductive rubber penetrating the rubber strip 1 in the thickness direction. Yes. In the present embodiment, a rectangular conductive region 1b is disposed at one end in the width direction of the rubber strip 1 having a rectangular cross section, and a rectangular nonconductive region 1a is disposed at the remaining portion.

Here, the non-conductive rubber refers to a rubber composition having a volume resistivity of 10 ⁸ Ω · cm or more, and is exemplified by a raw rubber blended with silica as a reinforcing agent in a high ratio. Examples of the raw rubber include natural rubber, styrene butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), butyl rubber (IIR), and the like. These may be used alone or in combination of two or more. Used. A vulcanizing agent, a vulcanization accelerator, a plasticizer, an anti-aging agent and the like are appropriately blended with the raw rubber.

In addition, the conductive rubber refers to a rubber composition having a volume resistivity of less than 10 ⁸ Ω · cm, and is exemplified by a raw rubber blended with carbon black as a reinforcing agent in a high ratio. In addition to the carbon black, the conductive performance required for the conductive rubber is not only carbon black, carbon-based carbon such as graphite, and metal-based known metal powder, metal oxide, metal flake, metal fiber, and the like. It can be obtained by blending a predetermined amount of the conductivity imparting material.

  The molding and winding of the rubber strip 1 can be performed using, for example, a manufacturing facility as shown in FIG. This manufacturing equipment includes a rubber strip molding device 7 capable of molding a rubber strip 1 by co-extrusion of non-conductive rubber and conductive rubber, and a rotary support on which the rubber strip 1 supplied from the rubber strip molding device 7 is wound. 8 and a control device 9 for controlling the operation of the rubber strip forming device 7 and the rotary support 8.

  The rubber strip forming apparatus 7 includes a pair of extruders 10 and 20, a rubber unit 30 provided in common at the ends of the extruders 10 and 20, and a base 31 attached to the end of the rubber unit 30. The discharge port 31 a of the base 31 is opened in a shape corresponding to the cross-sectional shape of the rubber strip 1. The rotary support 8 is configured to be rotatable in the R direction about the shaft 8 a and is configured to be movable in the axial direction, and is disposed in front of the base 31 at a predetermined interval.

  The extruder 10 includes a hopper 11 into which a rubber material is charged, a screw 12 that feeds the rubber material forward, a cylindrical barrel 13 that contains the screw 12, and a drive device 14 that drives the screw 12. And a head portion 15 having a built-in gear pump connected to the distal end side of the barrel 13. The extruder 20 is configured in the same manner as the extruder 10, and includes a hopper 21, a screw 22, a barrel 23, a driving device 24, and a head portion 25. The control device 9 controls the driving and braking of the screws 12 and 22 and the gear pump, and the rotation and movement of the rotary support 8 in the axial direction.

  When a non-conductive rubber previously kneaded as a rubber material is put into the hopper 11 and a conductive rubber kneaded as a rubber material is put into the hopper 21, each rubber material moves forward while being kneaded by the screws 12 and 22, respectively. It is fed out and supplied to the rubber unit 30 through the head units 15 and 25. At this time, the rubber material is supplied in a fixed amount to the rubber unit 30 by the function of the gear pump built in the head units 15 and 25. In the rubber united portion 30, the non-conductive rubber is molded into a shape corresponding to the non-conductive region 1a, and the conductive rubber is molded into a shape corresponding to the conductive region 1b. It is pushed out from the discharge port 31a. Thereby, the rubber strip 1 as shown in FIG. 1 is shape | molded.

  The extruded rubber strip 1 is fed forward while the cross-sectional shape of the rubber strip 1 is adjusted by the roll 32, and is wound on the rotating support 8 along the tire circumferential direction. The roller 33 is provided to press the rubber strip 1 against the rotation support 8. In the present invention, the tread rubber may be formed by directly wrapping the rubber strip 1 on the rotating support 8, but a semi-finished product of a green tire having a carcass layer or a belt layer is formed on the rotating support 8. The tread rubber can also be formed by winding the rubber strip 1 thereon.

  FIG. 3 is a plan view of the rotary support 8. The arrow A corresponds to the tire circumferential direction, and the arrow B corresponds to the tire width direction and the axial direction of the rotary support 8. The winding of the rubber strip 1 is performed by rotating the rotary support 8 in the R direction with the winding start end fixed on the rotary support 8, and at this time, the rotary support 8 is moved in the axial direction. Thus, the winding position of the rubber strip 1 can be shifted and wound in a spiral shape. The rotational speed of the rotary support 8, the moving speed in the axial direction, and the moving pitch are controlled and adjusted by the control device 9, and the tread rubber 6 having a predetermined cross-sectional shape is appropriately formed.

  In the present embodiment, an example in which the tread rubber 6 having the cross-sectional shape shown in FIG. 4 is formed is shown. The tread rubber 6 is disposed on the outer peripheral side of the belt layer at the time of molding the tire, and constitutes a tire outer peripheral side portion of the tread portion. The tread rubber 6 of the present embodiment is made of non-conductive rubber having a high silica content, thereby exhibiting excellent fuel economy performance and WET braking performance. In addition, a conductive layer 5 formed of conductive rubber is extended from the tread surface toward the tread bottom surface at an end in the width direction of the tread rubber 6.

  As described above, the tread rubber 6 is formed by winding the rubber strip 1 in the tire circumferential direction. FIG. 5 is a cross-sectional view of the tread rubber 6 schematically showing the cross-sectional shape of the rubber strip 1, but in actuality, the end portions of the rubber strip 1 are overlapped with each other. More complicated. In the present embodiment, since the conductive layer 5 is provided only at the width direction end portion on the left side of the tread rubber 6 in FIG. 5, the end portion serves as the placement portion PP of the conductive layer 5, and the remaining portion is not disposed on the conductive layer 5. It becomes the installation location AP.

  In order to form the tread rubber 6, when the rubber strip 1 is wound along the tire circumferential direction, first, as shown in FIG. 6A, the conductive region 1b has a thickness at the portion PP where the conductive layer 5 is disposed. The rubber strips 1 are laminated so as to overlap in the direction, and the conductive layer 5 is provided by the conductive region 1b. Subsequently, as shown in FIG. And the finished cross-sectional shape of the tread rubber 6 may be completed. When the conductive region 1b is overlapped in the thickness direction, the position in the width direction of the conductive region 1b may be shifted and partially contacted as shown in the figure.

  In the present invention, since the conductive region 1b is partially arranged in the cross section of the rubber strip 1, the size of the conductive region 1b can be reduced while ensuring the width dimension of the rubber strip 1, for example, the width dimension W is 15 mm. In the rubber strip 1 having a thickness dimension T of 1.5 mm, the width dimension of the conductive region 1b can be 5 mm or less. Therefore, even if the rubber strips 1 are stacked as shown in FIG. 6A, the rubber strip 1 can be stably formed without collapsing.

  In contrast, when a single-layer rubber strip having only a conductive region is used as in the prior art, the stacked rubber strip is liable to collapse due to the small width of the rubber strip, and the operation becomes unstable. When the width dimension of the rubber strip is increased, the volume of the conductive layer becomes larger than necessary, so that the improvement effect by using non-conductive tread rubber is not sufficiently exhibited.

  The width dimension W of the rubber strip 1 is exemplified by 5 to 30 mm, but is preferably at least 10 mm or more from the viewpoint of preventing the rubber strip 1 stacked to provide the conductive layer 5 from collapsing. In addition, the width dimension of the conductive region 1b is 1 / th of the width dimension W of the rubber strip 1 from the viewpoint of suppressing the volume of the conductive layer 5 and sufficiently exerting the improvement effect by using non-conductive tread rubber. It is preferable that it is 3 or less. Furthermore, the thickness dimension T of the rubber strip 1 is exemplified by 0.5 to 3.0 mm.

  The rubber strip wound around the non-arranged portion AP of the conductive layer 5 is a rubber strip that does not include a conductive region as shown in FIG. 6B (in this embodiment, a single-layer rubber strip having only a non-conductive region). Preferably there is. The “rubber strip not including the conductive region” may be formed separately from the rubber strip 1 used for disposing the conductive layer 5. However, as described later, the rubber strip 1 includes the “conductive region included”. It is efficient and preferable to use it as it is.

  A base rubber (not shown) formed of conductive rubber is laminated on the inner periphery of the formed tread rubber 6, and the conductive layer 5 extends from the tread surface in the tire radial direction (vertical direction in FIG. 6) to form the base rubber. Will reach. Thereby, static electricity generated in the vehicle body through the conductive layer 5 can be discharged to the road surface, and various problems such as radio noise can be prevented. The conductive layer 5 only needs to be in contact with a conductive rubber member provided adjacent to the tread rubber 6 and can be in contact with a wing rubber or a side wall rubber in addition to the base rubber.

  FIG. 6 shows an example in which the finished cross-sectional shape of the tread rubber 6 is completed by winding the rubber strip 1 around the placement location PP and providing the conductive layer 5 and then winding the rubber strip around the non-location location AP. However, the order in which the conductive layer 5 is provided is not particularly limited in the present invention. Therefore, after the rubber strip is wound around the non-arranged portion AP, the finished cross-sectional shape of the tread rubber 6 may be completed by winding the rubber strip 1 around the disposed portion PP and providing the conductive layer 5.

  In the present embodiment, an example in which the location PP of the conductive layer 5 is the width direction end portion (shoulder portion) of the tread rubber 6 is shown, but the present invention is not limited to this, and the mediate portion of the tread rubber 6 or You may provide the conductive layer 5 in a center part. However, it is preferable to provide the conductive layer 5 at a position that avoids the formation portion of the groove so that the conductive layer 5 is exposed on the surface of the land portion of the tread rubber 6. be able to.

  As described above, the rubber strip 1 used for disposing the conductive layer 5 can be used as the rubber strip wound around the non-arranged portion AP of the conductive layer 5. In this case, a non-conductive section S in which the conductive region 1b is replaced with the non-conductive region 1a is formed in at least a part of the longitudinal direction of the rubber strip 1, and the rubber strip 1 is placed so that the non-conductive section S overlaps in the thickness direction. What is necessary is just to laminate.

  Specifically, when the rubber strip 1 is wound on the rotating support 8 along the tire circumferential direction, the rubber strip 1 is laminated so that the conductive region 1b overlaps in the thickness direction at the location PP where the conductive layer 5 is disposed. Then, in the non-arranged portion AP of the conductive layer 5, the extrusion of the conductive rubber is stopped to form a non-conductive section S in which the conductive area 1 b is replaced with the non-conductive area 1 a, and the non-conductive section S extends in the thickness direction. The rubber strips 1 are laminated so as to overlap.

  That is, when the rubber strip 1 is wound around the non-arranged portion AP of the conductive layer 5, the rotation of the gear pump in the head portion 25 is stopped, and if necessary, the rotation of the screw 22 is also stopped, and the conductive rubber is pushed out. Then, as shown in FIG. 7, a non-conductive section S is formed by replacing the conductive area 1b with the non-conductive area 1a, and the rubber strip 1 is laminated so that the non-conductive sections S overlap. 7 indicates a start position where the conductive region 1b is replaced with the non-conductive region 1a, and the portion after this position is formed as a non-conductive section S. When forming the non-conductive section S, the rotational speed of the gear pump in the head portion 15 is increased, and if necessary, the rotational speed of the screw 12 is also increased, thereby increasing the extrusion amount of the non-conductive rubber and the rubber strip 1. The cross-sectional shape can be maintained. The operation control of the gear pumps in the head portions 15 and 25 and the screws 12 and 22 can be performed by the control device 9.

  As described above, in the present invention, not only the rubber strip 1 including the non-conductive region 1a and the conductive region 1b is wound and laminated around the place PP where the conductive layer 5 is provided, but also in the place AP where the conductive layer 5 is not provided. It is preferable to wind the rubber strip 1 after replacing the conductive region 1b with the non-conductive region 1a. Thereby, it is possible to improve the working efficiency by continuously forming the rubber strip 1 without interrupting the extrusion.

  Further, by performing the reverse operation to that described above, the rubber strip 1 formed as the non-conductive section S can be returned to the original state including the non-conductive area 1a and the conductive area 1b. Can be formed intermittently, and a winding path as shown in FIG. In the example of FIG. 8, the rubber strip 1 is continuously wound from one end to the other end in the width direction of the tread rubber 6 to form the first layer 61, and then folded back to the second layer on the first layer 61. The second layer 62 is formed and folded back again to form the third layer 63 on the second layer 62. In this case, the rubber strip 1 is alternately wound around the placement location PP and the non-location location AP, and the non-conductive section S is intermittently formed.

  According to such a tread rubber forming step, the location PP of the conductive layer 5 can be easily changed, so that the conductive layer 5 can be easily provided at various positions according to the pattern design. Even when a plurality of conductive layers 5 are formed, the manufacturing process does not become complicated. In addition, since the non-conductive section S having a shorter circumference than the tread rubber 6 can be formed, not only can the volume of the conductive layer 5 be significantly reduced, but also in complex pattern designs including blocks and zigzag ribs, The conductive layer 5 can be easily provided at a position that avoids the formation of the groove.

[Other Embodiments]
(1) In the above-described embodiment, an example in which a rubber strip is supplied from a rubber strip forming apparatus and wound is shown. However, in the present invention, a rubber strip formed by extrusion or the like is once wound up into a roll shape and wound up. The rubber strip may be supplied and wound while being unwound from a roll. Even in such a case, it is possible to wind around the non-disposed portion of the conductive layer as described above by forming the non-conductive section in the rubber strip in advance in consideration of the winding path and the like.

  (2) In the above-described embodiment, an example in which the conductive region is arranged at one end in the width direction of the rubber strip is shown. However, the present invention is not limited to this, and for example, both sides in the width direction as shown in FIG. A rubber strip 1 having a conductive region 1b disposed at the end thereof may be used. At this time, the winding path of the rubber strip 1 is exemplified by the one shown in FIG. 10, and two conductive layers extending in the oblique direction are provided at both ends of the tread rubber in the width direction. As described above, the conductive performance can be effectively improved by providing the conductive layers at the ends on both sides in the width direction of the tread rubber.

  (3) In the above-described embodiment, the example in which the conductive region is arranged at the end portion in the width direction of the rubber strip has been shown. However, the present invention is not limited to this. You may use the rubber strip 1 by which the electroconductive area | region 1b was distribute | arranged. At this time, examples of the winding path of the rubber strip 1 include those shown in FIGS. 12 and 13, and the conductive layer 5 is provided at the center in the width direction of the tread rubber. However, when the rubber strip is spirally wound along the tire circumferential direction, the conductive region is arranged in the width direction of the rubber strip as in the above-described embodiment from the viewpoint of easily and reliably overlapping the conductive regions. It is preferable that it is arranged at the end.

  (4) The cross-sectional shape of the rubber strip is not limited to the rectangular shape as in the above-described embodiment, and various shapes that can be employed in a normal strip build method such as a trapezoidal shape, a triangular shape, or a crescent shape can be applied. In addition, the cross-sectional shape of the conductive region is not limited to the rectangular shape as in the above-described embodiment, and may be a square shape, a trapezoidal shape, or other various types as long as the conductive regions overlap in the thickness direction between the laminated rubber strips. The shape can be applied.

  (5) In the present invention, the cross-sectional shape of the rubber strip may be changed during winding. For example, when the cross-sectional area of the rubber strip is large on the tread bottom surface side and small on the tread surface side, the rubber strip winding is more stable, and, for example, the central portion and both end portions are smoothly connected in the winding path shown in FIG. be able to. The cross-sectional shape of the rubber strip can be changed by attaching a variable die to the tip of the rubber united portion or increasing the rotational speed of the rotary support 8 to apply tension to the rubber strip 1.

Sectional drawing which shows an example of the rubber strip used by this invention Schematic configuration diagram showing manufacturing equipment for winding rubber strips Top view of rotating support Sectional drawing which shows an example of the tread rubber formed by this invention Cross section of tread rubber schematically showing the cross section of rubber strip The figure explaining the formation process of tread rubber Diagram explaining non-conductive section The figure explaining the formation process of tread rubber Sectional view showing another example of rubber strip The figure explaining the formation process of the tread rubber using the rubber strip of FIG. Sectional view showing another example of rubber strip The figure explaining the formation process of the tread rubber using the rubber strip of FIG. The figure explaining the formation process of the tread rubber using the rubber strip of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rubber strip 1a Non-conductive area 1b Conductive area 5 Conductive layer 6 Tread rubber 7 Rubber strip molding device 8 Rotating support 9 Control device 10 Extruder 12 Screw 14 Drive device 15 Head portion 20 Extruder 22 Screw 24 Drive device 25 Head portion 30 Rubber unit 31 Base AP Conductive layer non-placement PP Conductive layer placement place S Nonconductive section

Claims (3)

In a method for manufacturing a pneumatic tire including a step of forming a tread rubber by winding a rubber strip along a tire circumferential direction,
A cross section of the rubber strip is partitioned into a plurality of regions including a non-conductive region formed of non-conductive rubber and a conductive region formed of conductive rubber penetrating the rubber strip in the thickness direction. Has been
When the rubber strip is wound along the tire circumferential direction, the rubber strip is laminated so that the conductive region overlaps in the thickness direction, and a conductive layer extending from the tread surface toward the tread bottom surface is provided by the conductive region. A method for producing a pneumatic tire. The rubber strip has a non-conductive section in which at least a part of the longitudinal direction is replaced with the non-conductive area.
2. The pneumatic tire according to claim 1, wherein when the rubber strip is wound along a tire circumferential direction, the rubber strip is laminated so that the non-conductive section overlaps in the thickness direction at a portion where the conductive layer is not provided. Manufacturing method. Using a rubber strip molding device capable of molding the rubber strip by co-extrusion of non-conductive rubber and conductive rubber, and a rotating support body around which the rubber strip supplied from the rubber strip molding device is wound,
When the rubber strip is wound on the rotating support body along the tire circumferential direction, the rubber strip is laminated so that the conductive region overlaps in the thickness direction at the conductive layer disposition place. At the non-arranged portion, the extrusion of the conductive rubber is stopped to form a non-conductive section in which the conductive area is replaced with the non-conductive area, and the rubber strip is laminated so that the non-conductive section overlaps in the thickness direction. The method for producing a pneumatic tire according to claim 1.

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