JP6040067B2 - Pneumatic tire manufacturing method and pneumatic tire - Google Patents

Description

  The present invention relates to a method for manufacturing a pneumatic tire capable of discharging static electricity generated in a vehicle body or a tire to a road surface, and the pneumatic tire.

  In recent years, for the purpose of reducing rolling resistance, which is closely related to the reduction in fuel consumption of vehicles, it has been proposed to form tire constituent members from non-conductive rubber. For example, when the tread rubber is formed of non-conductive rubber with a high silica content, the rolling resistance can be reduced and the braking performance (wet braking performance) on a wet road surface can be improved. In order to enhance the effect of reducing rolling resistance, it is effective to form the topping rubber or sidewall rubber of the carcass ply with non-conductive rubber.

  However, when the topping rubber and sidewall rubber of the carcass ply are made of non-conductive rubber, there is a problem that discharge of static electricity generated in the vehicle body and tires to the road surface is hindered and problems such as radio noise are likely to occur. Therefore, in such a case, as described in Patent Documents 1 and 2, for example, it is necessary to form a conductive path on the tire side portion using conductive rubber.

JP 2007-8269 A JP 2011-517640 A

  This invention is made | formed in view of the said situation, The objective is to provide the manufacturing method of the pneumatic tire which can provide the electrically conductive path | route of a tire side part easily, and the pneumatic tire. .

  The above object can be achieved by the present invention as described below. That is, the method for manufacturing a pneumatic tire according to the present invention includes a step of forming a carcass ply formed by topping non-conductive rubber on a plurality of carcass cords arranged in parallel, and the formed carcass ply Forming a green tire in which the carcass ply is wound up from the inside in the tire width direction around the bead core in combination with another tire constituent member including a side wall rubber formed of conductive rubber, and The step of molding the carcass ply or the green tire includes the step of forming, on the surface of the carcass ply, a first conductive layer extending from the winding end of the carcass ply to the tread portion, and molding the carcass ply or the green tire. And the step of extending from the winding end of the carcass ply inward in the tire radial direction, Forming a second conductive layer connected to the first conductive layer at a flange end on the back surface of the carcass ply; the molded green tire includes a first ground contact surface that is in contact with a road surface; A conductive path to the conductive layer is provided in the tread portion, and a conductive path from the outer surface of the bead portion that can contact the rim to the second conductive layer is provided in the bead portion.

  According to this method, by using a structure in which the carcass ply is wound around the bead core, the conductive path on the tire side portion can be easily provided by the conductive layers formed on the front and back surfaces of the carcass ply. The conductive path on the side portion of the tire is electrically connected to the road surface via a conductive path formed on the tread portion, and is electrically connected to the rim via a conductive path formed on the bead portion. Therefore, static electricity generated in the vehicle body and the tire can be discharged to the road surface through these conductive paths.

  In the method for manufacturing a pneumatic tire according to the present invention, it is preferable that at least one of the first conductive layer and the second conductive layer is formed by applying a conductive liquid to the carcass ply. Thereby, a conductive layer can be easily formed on the carcass ply. In addition, the weight of the conductive layer can be significantly reduced as compared with the case where another member such as a rubber tape is added, and the occurrence of process defects such as air entry can be suppressed.

  In the method for manufacturing a pneumatic tire according to the present invention, it is preferable that at least one of the first conductive layer and the second conductive layer is formed in a strip shape, and a plurality of the conductive layers are arranged at intervals in the tire circumferential direction. In this case, since the conductive layer is formed elongated along the width direction of the carcass ply, the amount of conductive rubber can be reduced, and the rolling resistance reduction effect can be enhanced.

  In the method for manufacturing a pneumatic tire according to the present invention, it is preferable that the circumferential positions of the first conductive layer and the second conductive layer connected thereto are shifted from each other. Thereby, the influence of the tackiness fall by the conductive layer formed in the surface and the back surface of the carcass ply can be suppressed.

  In the method for manufacturing a pneumatic tire according to the present invention, the first conductive layer and the second conductive layer on one side in the tire width direction, and the first conductive layer and the second conductivity on the other side in the tire width direction. What shifts the circumferential position with respect to the layer is preferable. Thereby, the influence of the tackiness fall by the conductive layer formed in the surface and the back surface of the carcass ply can be suppressed.

  The pneumatic tire according to the present invention includes a pair of bead portions in which a bead core is embedded, a sidewall portion extending outward in the tire radial direction from each of the bead portions, and an outer side in the tire radial direction of each of the sidewall portions. A tread portion connected to an end, a carcass ply that extends from the tread portion through the sidewall portion to the bead portion and winds around the bead core from the inner side in the tire width direction, and the carcass ply at the sidewall portion. In a pneumatic tire provided with a side wall rubber provided on the outside of the carcass ply, the topping rubber of the carcass ply and the side wall rubber are formed of non-conductive rubber, and the carcass ply is formed on the surface of the carcass ply. And from the winding end of the carcass ply to the tread portion. A first conductive layer; and a second conductive layer formed on a back surface of the carcass ply and extending inward in a tire radial direction from a winding end of the carcass ply, and connected to the first conductive layer at the winding end. The tread portion is provided with a conductive path from the ground surface that can contact the road surface to the first conductive layer, and the bead portion includes the second conductive material from the outer surface of the bead portion that can contact the rim. Conductive paths leading to the layers are provided.

  According to this tire, the conductive path on the side portion of the tire is provided by the conductive layers formed on the front and back surfaces of the carcass ply. The conductive path on the side portion of the tire is electrically connected to the road surface via a conductive path formed on the tread portion, and is electrically connected to the rim via a conductive path formed on the bead portion. Therefore, static electricity generated in the vehicle body and the tire can be discharged to the road surface through these conductive paths.

Tire meridian half section view showing an example of pneumatic tire (A) perspective view and (B) cross-sectional view showing the main parts of the carcass ply Configuration diagram schematically showing an example of a process for molding a carcass ply Sectional drawing which shows a part of process of shaping | molding a green tire roughly The figure which shows notionally the example of the positional relationship of a 1st conductive layer and a 2nd conductive layer Sectional drawing which shows another form of the electroconductive path | route provided in a tread part

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The pneumatic tire T shown in FIG. 1 includes a pair of bead portions 1 in which bead cores 1a are embedded, sidewall portions 2 extending from the bead portions 1 outward in the tire radial direction, and sidewall portions 2 respectively. A tread portion 3 connected to an outer end in the tire radial direction of the tire, a carcass ply 7 wound from the tread portion 3 to the bead portion 1 through the sidewall portion 2 and wound around the bead core 1a from the inner side in the tire width direction, Side wall rubber 11 provided outside the carcass ply 7 at the wall portion 2 is provided. The annular bead core 1a is formed by covering a converging body such as a steel wire with rubber.

  The carcass ply 7 includes a plurality of carcass cords 7C (see FIG. 3) arranged in parallel to each other. The carcass cord 7C is aligned in a direction substantially orthogonal to the tire circumferential direction and is covered with a topping rubber. As the material of the carcass cord 7C, organic fibers such as polyester, rayon, nylon, and aramid, and metals such as steel are preferably used. An inner liner rubber 9 for holding air pressure is provided inside the carcass ply 7.

  The carcass ply 7 includes a main body portion 71 that extends from the tread portion 3 through the sidewall portion 2 to the bead portion 1 and a winding portion 72 that is wound around the bead core 1a from the inner side in the tire width direction to the outer side. The front surface 7A of the carcass ply 7 is a surface facing the outer peripheral side in the main body portion 71, and the rear surface 7B of the carcass ply 7 is a surface facing the inner peripheral side in the main body portion 71. A first conductive layer 21 (hereinafter referred to as a conductive layer 21), which will be described later, extends along the main body 71 and the winding portion 72 on the front surface 7A, and a second conductive layer 22 (hereinafter referred to as the conductive layer 22) is a winding portion on the back surface 7B. 72 extends along.

  The tread portion 3 is provided with a tread rubber 10 that constitutes a contact surface, a belt 6 that contacts the carcass ply 7 from the outer side in the tire radial direction, and a belt reinforcing member 8 that is laminated on the outer side in the tire radial direction of the belt 6. It has been. A tread conductive portion 13 is embedded in the tread rubber 10. In FIG. 1 and the like, the conductive layers 21 and 22 and the tread conductive portion 13 are shown in black to facilitate distinction on the drawing. In the tire T, a tread-on-side structure in which the end portion of the tread rubber 10 is placed on the end portion of the sidewall rubber 11 is employed, but the present invention is not limited to this.

  The belt 6 includes a plurality (two in this embodiment) of belt plies 6a and 6b. The belt plies 6a and 6b include a plurality of belt cords arranged in parallel, and are laminated so that they cross each other in opposite directions between the belt plies. The belt cord is aligned at an inclination angle of, for example, about 20 ° with respect to the tire circumferential direction, and is covered with a topping rubber. The belt reinforcing member 8 includes a reinforcing cord that extends substantially in the tire circumferential direction, and the reinforcing cord is covered with a topping rubber. The belt reinforcing material 8 may be omitted.

  The bead portion 1 is provided with a rim strip rubber 4 constituting the side surface of the bead portion 1 and a rubber chacher 5 constituting the bottom surface of the bead portion 1. A side wall rubber 11 connected to the rim strip rubber 4 constitutes a side surface of the side wall portion 2. The rim strip rubber 4 is located on the outer side in the tire width direction of the winding-up portion 72 and contacts the rim flange of the rim when the rim is mounted. The rubber chacher 5 is located on the inner side in the tire radial direction of the winding-up portion 72, and contacts the rim bead sheet when the rim is mounted.

  As shown in FIG. 2, the carcass ply 7 is formed on the front surface 7 </ b> A of the carcass ply 7 and formed on the conductive layer 21 extending from the winding end 7 </ b> E of the carcass ply 7 to the tread portion 3, and on the back surface 7 </ b> B of the carcass ply 7. And it has the conductive layer 22 extended in the tire radial direction inner side from the winding-up end 7E of the carcass ply 7, and connected to the conductive layer 21 at the winding-up end 7E. That is, in the carcass ply 7, a continuous conductive region composed of the conductive layer 21 and the conductive layer 22 is formed in the range indicated by the arrow 20 in FIG. 2B, thereby providing a conductive path on the tire side portion. ing.

  In the tire T, the topping rubber and the side wall rubber 11 of the carcass ply 7 are formed of nonconductive rubber. The conductive layers 21 and 22 are each formed of conductive rubber. The tread portion 3 is provided with a conductive path from the ground contact surface that can come into contact with the road surface to the conductive layer 21, and the conductive path on the side of the tire can be electrically connected to the road surface through the conductive path. The bead portion 1 is provided with a conductive path from the side surface of the bead portion 1 that can come into contact with a rim (not shown) to the conductive layer 22, and the conductive path on the tire side portion is electrically connected to the rim via the conductive path. Can be conducted.

  In the present embodiment, the tread rubber 10 is formed of non-conductive rubber, and the tread conductive portion 13 provided therein is formed of conductive rubber. As shown in FIG. 1, the tread conductive portion 13 continuously extends from one end exposed on the ground surface to the other end reaching the surface 7 </ b> A of the carcass ply 7, and the other end is connected to the conductive layer 21. As described above, the conductive path provided in the tread portion 3 is constituted by the tread conductive portion 13. The topping rubber of the belt 6 and the topping rubber of the belt reinforcing member 8 may be formed of non-conductive rubber.

  Furthermore, in this embodiment, the rim strip rubber 4 is formed of conductive rubber. The rim strip rubber 4 constitutes the side surface of the bead portion 1 that comes into contact with the rim when the rim is mounted, and is in contact with the winding portion 72 from the outer side in the tire width direction and formed on the back surface 7B of the carcass ply 7 as shown in FIG. Connected to the conductive layer 22. As described above, the conductive path provided in the bead portion 1 is constituted by the rim strip rubber 4 itself.

  Static electricity generated in the vehicle body or tire is constituted by the conductive path of the bead portion 1 formed by the rim strip rubber 4, the conductive path of the tire side portion using the conductive layers 21 and 22, and the tread conductive portion 13 from the rim. To the road surface through the conductive path of the tread portion 3 The conductive rubber that forms the conductive path on the side of the tire only requires the amount of the conductive layers 21 and 22, so that it rolls compared to the conventional tire in which the topping rubber and sidewall rubber of the carcass ply are formed of conductive rubber. The effect of reducing resistance is enhanced. Such a conductive path from the rim to the ground plane may be provided on at least one side in the tire width direction.

The non-conductive rubber refers to a rubber having a specific resistance value exceeding 10 ⁸ Ω · cm. For example, the non-conductive rubber is produced by blending silica as a reinforcing agent in a high ratio with raw material rubber. The silica is blended at 30 to 100 parts by weight with respect to 100 parts by weight of the rubber component, for example. As silica, wet silica can be preferably used, but those commonly used as reinforcing materials can be used without limitation. The nonconductive rubber may be prepared by blending calcined clay, hard clay, calcium carbonate, or the like, in addition to silicas such as precipitated silica and anhydrous silicic acid.

  In addition, as the reinforcing agent to be blended with the raw rubber, the non-conductive rubber may be composed mainly of carbon black that does not contain silica or is blended with a low ratio of silica and highly dispersed. When the topping rubber or the sidewall rubber 11 of the carcass ply 7 is formed of such non-conductive rubber, the rigidity of the tire side portion is increased and the steering stability performance is improved while suppressing an increase in rolling resistance. Can do.

The conductive rubber refers to rubber having a specific resistance value of 10 ⁸ Ω · cm or less, and is produced, for example, by blending carbon black as a reinforcing agent in a high ratio with raw material rubber. For example, the carbon black is blended in an amount of 30 to 100 parts by weight with respect to 100 parts by weight of the rubber component. In addition to carbon black, the conductive rubber can be blended with carbon fiber, graphite or other carbon-based materials, and metal-based known conductivity imparting materials such as metal powders, metal oxides, metal flakes, and metal fibers. can get.

  Examples of the raw rubber include natural rubber, styrene butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), and butyl rubber (IIR). 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. Moreover, said specific resistance value points out the volume specific resistance measured at 23 degreeC based on JISK6271.

  Next, a method for manufacturing the pneumatic tire T will be described. Since the manufacturing method of the pneumatic tire according to the present invention can be performed in the same manner as the conventional tire manufacturing except that the first and second conductive layers are formed, the first and second conductive layers are formed. The explanation is centered.

  This pneumatic tire manufacturing method includes a step of forming a carcass ply 7 formed by topping non-conductive rubber on a plurality of carcass cords 7C arranged in parallel, and the formed carcass ply 7 is used as a side wall rubber. And a step of forming a green tire in which the carcass ply 7 is wound up around the bead core 1a from the inner side in the tire width direction to the outer side in combination with other tire constituent members including 11. Furthermore, a vulcanization process for vulcanizing the green tire is provided, and the vulcanized pneumatic tire shown in FIG. 1 is obtained through these processes.

  In the process of forming the carcass ply 7, for example, the apparatus shown in FIG. 3 is used. In this apparatus, a large number of carcass cords 7 </ b> C fed out from the bobbin 51 are supplied to the extruder 52 in a state of being arranged in parallel with each other, and are covered with nonconductive rubber fed from the cylinder 53. The extruded ply-shaped ply material is cut to a predetermined length by the cutter 54 to form a strip-like ply material 70, and the strip-like ply material 70 is arranged and sequentially joined to form the carcass ply 7.

  The molding of the carcass ply 7 is not limited to the method using the extruder as described above. For example, a method of feeding a plurality of carcass cords arranged in parallel between a pair of calender rolls and covering them with a sheet-like non-conductive rubber molded with the calender rolls, or a plurality of carcass cords arranged in parallel A method of sandwiching from above and below with a non-conductive rubber sheet can also be adopted. The carcass ply 7 is formed with a length corresponding to the tire circumferential length, but may be formed into a long shape and wound on a roll.

  In the step of forming the raw tire, for example, the carcass ply 7 is wound around the forming drum 30 as shown in FIG. 4 (A) and formed into an annular shape, and then the bead core 1a is set at a predetermined position, as shown in FIG. Thus, the end of the carcass ply 7 is wound up. The forming drum 30 may be supplied with a carcass ply having a length corresponding to the tire circumferential length, or may be supplied with a carcass ply drawn from a roll and cut at a required length. Although not illustrated, the inner liner rubber 9 and the like are also wound around the molding drum 30, and after winding up the end of the carcass ply 7, other components including the sidewall rubber 11 are combined.

  The conductive layer 21 and the conductive layer 22 are formed in the process of forming the carcass ply 7 or the green tire, respectively. That is, the process of molding the carcass ply 7 or the green tire includes a step of forming the conductive layer 21 from the winding end 7E to the tread portion 3 on the surface 7A of the carcass ply 7. The process of forming the carcass ply 7 or the green tire is formed on the back surface 7B of the carcass ply 7 with the conductive layer 22 extending inward in the tire radial direction from the winding end 7E and connected to the conductive layer 21 at the winding end 7E. Including the steps of:

  In the case of forming the conductive layers 21 and 22 in the process of forming the carcass ply 7, for example, it is conceivable to apply a conductive liquid material to the formed carcass ply 7 as shown in FIG. The roller 31 applies a conductive liquid material to a predetermined region of the front surface 7A and the back surface 7B so that the conductive layer 22 is connected to the conductive layer 21 at the winding end 7E that is a cut end portion of the carcass ply 7. For application of the conductive liquid material, brush or spray can be used as appropriate. Further, the conductive layers 21 and 22 may be formed on the strip-like ply material 70 before joining.

  When forming the conductive layers 21 and 22 in the process of forming a green tire, for example, as shown in FIG. 4, it is conceivable to apply a conductive liquid to the carcass ply 7 at the time of tire formation. The roller 32 in FIG. 4A applies a conductive liquid material to a predetermined region of the surface 7A of the carcass ply 7 to form the conductive layer 21, and the roller 33 in FIG. A conductive liquid material is applied to a predetermined region 7B to form a conductive layer 22.

  The conductive layer 21 and the conductive layer 22 may be formed in different steps. For example, it is conceivable that the conductive layer 22 is formed on the back surface 7B in the process of forming the carcass ply 7 and the conductive layer 21 is formed on the front surface 7A in the process of forming a green tire. Further, in order to securely connect the conductive layer 21 and the conductive layer 22, the conductive liquid material is applied to the front surface 7 </ b> A and the back surface 7 </ b> B by applying the conductive liquid material to the winding end 7 </ b> E that is the cut end portion of the carcass ply 7. You may set separately from the operation | work which apply | coats. Moreover, it can replace with a conductive liquid substance and can also form the conductive layers 21 and 22 using a rubber tape.

  Examples of the conductive liquid include conductive rubber paste obtained by mixing a conductive rubber with an organic solvent and dissolving a rubber component in the organic solvent. The composition of the conductive rubber paste is not particularly limited as long as the required energization performance can be obtained. For example, 100 parts by weight of SBR (styrene butadiene rubber), 80 parts by weight of carbon black, and 40 parts by weight of highly aromatic process oil are mixed with wax. It is prepared by stirring and dissolving a rubber composition to which stearic acid, anti-aging agent, zinc white, vulcanization accelerator, sulfur and the like are added in volatile oil for rubber.

  The conductive layers 21 and 22 of this embodiment are formed into a thin film by applying conductive rubber paste to the front surface 7A and the back surface 7B of the carcass ply 7, and drying and vulcanizing and curing. Therefore, the thickness is smaller than that of the conductive layer formed of the rubber sheet, the weight of the conductive layer can be greatly reduced, and the occurrence of process defects such as air entry can be suppressed. The conductive rubber paste has a thickness of the thin film constituting the conductive layers 21 and 22 after vulcanization molding, preferably 0.001 to 0.3 mm, more preferably 0.001 to 0.05 mm. It is applied as follows.

  At least one of the first and second conductive layers is preferably formed in a strip shape. In this embodiment, both of the conductive layers 21 and 22 are formed in a strip shape. As a result, the conductive layer is formed elongated along the width direction of the carcass ply 7, and the amount of conductive rubber can be reduced to increase the rolling resistance reduction effect. The conductive layers 21 and 22 are arranged in plural (that is, two or more) at intervals in the tire circumferential direction, and preferably they are arranged at equal intervals in the tire circumferential direction. 10-50 mm is preferable and, as for the width W of the conductive layers 21 and 22 which make strip | belt shape, 20-40 mm is more preferable.

  In this embodiment, the positions in the circumferential direction of the conductive layer 21 and the conductive layer 22 connected to the conductive layer 21 are the same as shown in FIG. 5A. However, the present invention is not limited to this, and as shown in FIG. It is preferable to shift the circumferential positions of each other. Thereby, the influence of the tackiness fall by the conductive layers 21 and 22 can be suppressed. That is, by not concentrating the places where the tackiness is lowered, it is possible to prevent adverse effects on the adhesion between the carcass ply 7 and other tire constituent members (sidewall rubber 11, rim strip rubber 4, etc.) to be bonded thereto.

  When the conductive layers 21 and 22 are formed on both sides in the tire width direction, the conductive layers 21 and 22 on one side in the tire width direction as shown in FIG. It is preferable that the positions in the circumferential direction of the conductive layers 21 and 22 on the other side are shifted from each other and arranged in a staggered manner. 5C, the circumferential positions of the conductive layer 21 and the conductive layer 22 can be shifted as shown in FIG. 5B. The conductive layers 21 and 22 of the present embodiment are formed on both sides in the tire width direction so as not to be continuous in the vicinity of the center line CL of the carcass ply 7, but may be only one side.

  From the viewpoint of suppressing the rolling resistance by reducing the amount of conductive rubber and suppressing the decrease in tackiness while securing the energization performance, the width of the carcass ply 7 is half the width direction with respect to the area of the surface 7A of the carcass ply 7. The area ratio (area ratio) of the conductive layer 21 is preferably 15 to 50%. For the same reason, the ratio of the area of the conductive layer 22 to the area of the back surface 7B of the carcass ply 7 (area ratio) is preferably 15 to 30% for the half of the carcass ply 7 in the width direction.

  In the molded green tire, a conductive path from the ground contact surface that can contact the road surface to the conductive layer 21 is provided in the tread portion 3, and a conductive path from the outer surface of the bead portion 1 that can contact the rim to the conductive layer 22. Is provided in the bead portion 1. As described above, in the present embodiment, the conductive path of the tread portion 3 is constituted by the tread conductive portion 13, and the conductive path of the bead portion 1 is constituted by the rim strip rubber 4 itself. The tread conductive portion 13 and the rim strip rubber 4 are connected to the conductive layers 21 and 22 in the process of forming a green tire, respectively.

  The shape of the conductive path provided in the tread portion 3 is not particularly limited as long as the conductive path on the tire side portion can be electrically connected to the road surface. For example, as shown in FIG. 6, a tread conductive portion 14 having one end exposed on the ground surface and the other end exposed on the bottom surface of the tread rubber 10 may be provided. In this case, the topping rubber of each of the belt reinforcing member 8 and the belt 6 is formed of conductive rubber, and the conductive layer 21 is extended to a position where it contacts the belt 6, thereby providing a conductive path from the ground plane to the conductive layer 21. It is done. Alternatively, the tread rubber 10 may be formed of a conductive rubber, thereby providing a required conductive path in the tread portion 3.

  The shape of the conductive path formed in the bead portion 1 is not particularly limited as long as the conductive path on the tire side portion can be electrically connected to the rim. For example, the rim strip rubber 4 may be formed of non-conductive rubber, and a conductive portion formed of conductive rubber may be embedded therein. In that case, one end of the conductive portion formed inside the rim strip rubber 4 is connected to the second conductive layer, and the other end of the conductive portion is exposed on the side surface of the bead portion 1 that can come into contact with the rim. A conductive path from the side surface to the second conductive layer is provided.

  The outer surface of the bead portion 1 that can come into contact with the rim includes not only the side surface of the bead portion 1 but also the bottom surface of the bead portion 1 that comes into contact with the bead sheet of the rim when the rim is mounted. Therefore, the conductive path provided in the bead part 1 may reach the second conductive layer from the bottom surface of the bead part 1. In that case, a conductive portion built in the rubber chafer 5 made of conductive rubber or the rubber chacher 5 made of non-conductive rubber is connected to the second conductive layer. The rim strip rubber 4 may be formed of non-conductive rubber.

  The present invention is not limited to the embodiment described above, and various improvements and modifications can be made without departing from the spirit of the present invention.

  Examples that specifically show the structure and effects of the present invention will be described below. Each performance evaluation of the tire was performed as follows.

(1) Energization performance (electric resistance)
If a predetermined load is applied to the tire mounted on the rim, and an electric resistance value measured by applying an applied voltage (500 V) from the shaft supporting the rim to the metal plate to which the tire contacts the ground is “Yes”, If it exceeded 100 MΩ, it was judged as “none”.

(2) Tackiness (durability test)
A peel test is performed on the belt ply and side wall rubber bonded to the surface of the carcass ply, and the case where it peels without resistance is “x”, the case where there is resistance and there is no rubber adhesion of the peeled member. The case where “Δ” was peeled off due to resistance and the rubber adhered to the peeled member was determined as “◯”.

  Except for the manner in which a conductive liquid (conductive rubber paste) is applied to the carcass ply, the tire structure and rubber composition in each example are common. However, in Comparative Example 1, the first conductive layer and the second conductive layer are not connected at the winding end of the carcass ply. The “number of locations” in Table 1 is the number in the tire circumferential direction of locations where a combination of the first conductive layer and the second conductive layer is formed on one side in the tire width direction. Similarly, the “area ratio” is the ratio of the area of the first conductive layer to the area of the surface of the carcass ply.

  As shown in Table 1, Comparative Example 1 does not have sufficient energization performance, while Examples 1-7 have energization performance. Further, in Examples 2 and 3, there is a slight influence due to the decrease in tackiness, but in Example 1 and Examples 4 to 7 in which conductive layers are dispersedly arranged in a plurality of locations and the area ratio is 50% or less, The influence of the decrease in tackiness is suppressed.

DESCRIPTION OF SYMBOLS 1 Bead part 1a Bead core 2 Side wall part 3 Tread part 4 Rim strip rubber 5 Rubber chaher 6 Belt 7 Carcass ply 7A Front surface 7B Back surface 7C Carcass cord 7E Winding end 10 Tread rubber 11 Side wall rubber 13 Tread conductive part 21 First conductive layer 22 Second conductive layer 71 Body portion 72 Winding portion

Claims (6)

Forming a carcass ply formed by topping non-conductive rubber on a plurality of carcass cords arranged in parallel;
Combining the molded carcass ply with other tire constituent members including sidewall rubber formed of non-conductive rubber, a raw tire in which the carcass ply is wound around the bead core from the inner side to the outer side in the tire width direction. A molding step,
Forming the carcass ply or the green tire includes a step of forming a first conductive layer from a rolled-up end of the carcass ply to a tread portion on a surface of the carcass ply;
The step of forming the carcass ply or the green tire extends from the winding end of the carcass ply to the inside in the tire radial direction, and the second conductive layer connected to the first conductive layer at the winding end includes the carcass ply. Including the step of forming on the back surface of
In the molded green tire, a conductive path from the ground contact surface that can contact the road surface to the first conductive layer is provided in the tread portion, and the second conductive layer extends from the outer surface of the bead portion that can contact the rim. The manufacturing method of the pneumatic tire by which the conductive path which leads to is provided in the said bead part.   The method for manufacturing a pneumatic tire according to claim 1, wherein at least one of the first conductive layer and the second conductive layer is formed by applying a conductive liquid to the carcass ply.   The method for manufacturing a pneumatic tire according to claim 1 or 2, wherein at least one of the first conductive layer and the second conductive layer is formed in a belt shape, and a plurality of the conductive layers are arranged at intervals in the tire circumferential direction.   The method for manufacturing a pneumatic tire according to any one of claims 1 to 3, wherein circumferential positions of the first conductive layer and the second conductive layer connected thereto are shifted from each other.   The circumferential positions of the first conductive layer and the second conductive layer on one side in the tire width direction and the first conductive layer and the second conductive layer on the other side in the tire width direction are shifted from each other. The manufacturing method of the pneumatic tire of any one of 1-4. From the tread portion, a pair of bead portions in which bead cores are embedded, sidewall portions extending outward in the tire radial direction from each of the bead portions, tread portions connected to the respective tire radial direction outer ends of the sidewall portions, and A carcass ply that reaches the bead portion through the sidewall portion and is rolled up from the inner side in the tire width direction around the bead core; and a sidewall rubber provided on the outer side of the carcass ply at the sidewall portion. In the provided pneumatic tire,
The carcass ply topping rubber and the sidewall rubber are formed of non-conductive rubber,
The carcass ply is formed on the surface of the carcass ply and has a first conductive layer extending from the winding end of the carcass ply to the tread portion, and is formed on the back surface of the carcass ply and the tire diameter from the winding end of the carcass ply. A second conductive layer extending inwardly and connected to the first conductive layer at the rolled-up end,
The tread portion is provided with a conductive path from a ground surface that can contact a road surface to the first conductive layer, and the bead portion includes an outer surface of the bead portion that can contact a rim and the second conductive layer. A pneumatic tire characterized in that a conductive path leading to is provided.

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