JP6354515B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can improve the durability of a conductive portion.

  In the pneumatic tire, a charge suppression structure using an earth tread is employed to discharge static electricity generated in the vehicle to the road surface when the vehicle is running. The earth tread is a conductive rubber that penetrates the cap tread and is exposed to the tire ground contact surface. In this charging suppression structure, static electricity from the vehicle is discharged from the belt layer to the road surface via the earth tread, and charging of the vehicle is suppressed.

  On the other hand, in recent years, there is a tendency to increase the silica content of rubber compounds constituting cap treads, undertreads, sidewall rubbers and the like in order to improve the fuel efficiency of the tire. Since silica has high insulating properties, when the silica content of the cap tread is increased, the resistance value of the cap tread is increased and the antistatic performance of the tire is lowered.

  For this reason, the conventional pneumatic tire includes a conductive portion that continuously extends from the bead portion to the belt layer in order to improve the charge suppression performance. As a conventional pneumatic tire employing such a configuration, for example, a technique described in Patent Document 1 is known.

JP 2014-133467 A

  An object of the present invention is to provide a pneumatic tire capable of improving the durability of a conductive portion.

In order to achieve the above object, a pneumatic tire according to the present invention includes a pair of bead cores, at least one carcass layer spanned between the pair of bead cores in a continuous or tread portion, and the carcass layer, A belt layer disposed on the outer side in the tire radial direction of the carcass layer; a tread rubber disposed on the outer side in the tire radial direction of the belt layer; and a pair of sidewall rubbers disposed on the outer side in the tire width direction of the carcass layer; A pneumatic tire including at least a conductive portion continuously extending from the bead portion to the belt layer, wherein the conductive portion has an electrical resistivity of less than 1 × 10 ^ 8 [Ω / cm]. conductive material have a conductive wire-like body formed by molding the linearized, and the periphery length Lp of the extending length La of the conductive portion in a predetermined region said carcass layer, 1.1 5 have a relationship ≦ La / Lp, and said carcass layer and the conductive portion extending lengths of La5 in the region of 15 [%] of the tire section height SH around the radially outer face of the bead core The peripheral length Lp5 has a relationship of 1.00 ≦ La5 / Lp5 ≦ 1.10 .
In addition, a pneumatic tire according to the present invention includes a pair of bead cores, at least one carcass layer spanned between the pair of bead cores with a continuous or divided tread portion, and a tire diameter of the carcass layer. A pneumatic tire comprising a belt layer disposed on the outer side in the direction, a tread rubber disposed on the outer side in the tire radial direction of the belt layer, and a pair of sidewall rubbers disposed on the outer side in the tire width direction of the carcass layer. And a conductive portion extending continuously from at least the bead portion to the belt layer, wherein the conductive portion is a linear conductive material having an electrical resistivity of less than 1 × 10 ^ 8 [Ω / cm]. A conductive linear body formed in a predetermined region, and the extension length La of the conductive portion in a predetermined region and the peripheral length Lp of the carcass layer are 1.15 ≦ La / Lp. The extension length La6 of the conductive portion and the belt width Wb in the region of 10% of the belt width Wb centered on the tire equatorial plane are 1.00 ≦ La6 / Wb ≦ 1. .10 relationship.
In addition, a pneumatic tire according to the present invention includes a pair of bead cores, at least one carcass layer spanned between the pair of bead cores with a continuous or divided tread portion, and a tire diameter of the carcass layer. A pneumatic tire comprising a belt layer disposed on the outer side in the direction, a tread rubber disposed on the outer side in the tire radial direction of the belt layer, and a pair of sidewall rubbers disposed on the outer side in the tire width direction of the carcass layer. And a conductive portion extending continuously from at least the bead portion to the belt layer, wherein the conductive portion is a linear conductive material having an electrical resistivity of less than 1 × 10 ^ 8 [Ω / cm]. A conductive linear body formed in a predetermined region, and the extension length La of the conductive portion in a predetermined region and the peripheral length Lp of the carcass layer are 1.15 ≦ La / Lp. A region extending between the tire maximum width position and the end of the belt width-wide outer belt ply of the belt layer from the outer end in the tire width direction to the outer periphery of the carcass layer. When the region between the tire maximum width position and the position of 1/3 of the tire cross-section height relative to the measurement point of the rim diameter is referred to as a radially inner region, the outer region is referred to as the radially outer region. The ratio La_out / Lp_out between the extension length La_out of the conductive portion and the peripheral length Lp_out of the carcass layer is determined by the extension length La_in of the conductive portion and the peripheral length Lp_in of the carcass layer in the radially inner region. It is characterized by being larger than the ratio La_in / Lp_in.
In addition, a pneumatic tire according to the present invention includes a pair of bead cores, at least one carcass layer spanned between the pair of bead cores with a continuous or divided tread portion, and a tire diameter of the carcass layer. A pneumatic tire comprising a belt layer disposed on the outer side in the direction, a tread rubber disposed on the outer side in the tire radial direction of the belt layer, and a pair of sidewall rubbers disposed on the outer side in the tire width direction of the carcass layer. And a conductive portion extending continuously from at least the bead portion to the belt layer, wherein the conductive portion is a linear conductive material having an electrical resistivity of less than 1 × 10 ^ 8 [Ω / cm]. A conductive linear body formed in a predetermined region, and the extension length La of the conductive portion in a predetermined region and the peripheral length Lp of the carcass layer are 1.15 ≦ La / Lp. And the conductive portion has a curved shape curved in the tire circumferential direction, and a distance D in the tire radial direction between the top of the curved shape and the tire maximum width position is 15 [mm]. It is characterized by being in the range of ≦ D.

  In the pneumatic tire configuration according to the present invention, the ratio La / Lp between the extension length La of the conductive portion and the peripheral length Lp of the carcass layer is set large in a predetermined region, so that the conductive portion is large. Arranged with slack. In such a configuration, when the tire is repeatedly bent and deformed when the tire rolls, the tension acting on the conductive portion is relaxed. Thereby, disconnection of the conductive portion is prevented, and there is an advantage that durability of the conductive portion is improved.

FIG. 1 is a sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment of the present invention. FIG. 2 is an explanatory view showing the charge suppression structure of the pneumatic tire shown in FIG. FIG. 3 is an enlarged cross-sectional view showing the earth tread described in FIG. 2. FIG. 4 is an explanatory view showing the arrangement structure of the conductive parts shown in FIG. FIG. 5 is an explanatory view showing a single conductive portion. FIG. 6 is an explanatory view showing a slack structure of the conductive portion shown in FIG. FIG. 7 is an explanatory view showing a modification of the slack structure of the conductive portion shown in FIG. FIG. 8 is an explanatory view showing a modification of the slack structure of the conductive portion shown in FIG. FIG. 9 is an explanatory view showing a modification of the slack structure of the conductive portion shown in FIG. FIG. 10 is an explanatory view showing a modification of the slack structure of the conductive portion shown in FIG. FIG. 11 is an explanatory view showing a modification of the slack structure of the conductive portion shown in FIG. FIG. 12 is an explanatory view showing a modification of the slack structure of the conductive portion shown in FIG. FIG. 13 is an explanatory view illustrating a modified example of the pneumatic tire depicted in FIG. 1. FIG. 14 is an explanatory view showing a modified example of the pneumatic tire depicted in FIG. 1. FIG. 15 is an explanatory view showing a modified example of the pneumatic tire shown in FIG. 1. FIG. 16 is an explanatory diagram illustrating a modification of the pneumatic tire depicted in FIG. 1. FIG. 17 is a chart showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention.

  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.

[Pneumatic tire]
FIG. 1 is a sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment of the present invention. This figure shows one side region in the tire radial direction. The figure shows a radial tire for a passenger car as an example of a pneumatic tire.

  In the figure, the cross section in the tire meridian direction means a cross section when the tire is cut along a plane including a tire rotation axis (not shown). Reference sign CL denotes a tire equator plane, which is a plane that passes through the center point of the tire in the tire rotation axis direction and is perpendicular to the tire rotation axis. Further, the tire width direction means a direction parallel to the tire rotation axis, and the tire radial direction means a direction perpendicular to the tire rotation axis.

  The pneumatic tire 1 has an annular structure centered on the tire rotation axis, and includes a pair of bead cores 11, a pair of bead fillers 12, 12, a carcass layer 13, a belt layer 14, and a tread rubber 15. A pair of side wall rubbers 16 and 16, a pair of rim cushion rubbers 17 and 17, an inner liner 18, and a pair of chafers 20 and 20 (see FIG. 1).

  The pair of bead cores 11 and 11 is an annular member formed by bundling a plurality of bead wires, and constitutes the core of the left and right bead portions. The pair of bead fillers 12 and 12 are disposed on the outer periphery in the tire radial direction of the pair of bead cores 11 and 11 to reinforce the bead portion.

  The carcass layer 13 has a single-layer structure composed of a single carcass ply or a multilayer structure formed by laminating a plurality of carcass plies, and is spanned in a toroidal manner between left and right bead cores to constitute a tire skeleton. The carcass ply of the carcass layer 13 is formed by coating a plurality of carcass cords made of steel or an organic fiber material (for example, aramid, nylon, polyester, rayon, etc.) with a coat rubber and rolling it, and has an absolute value of 80 It has a carcass angle (inclination angle in the fiber direction of the carcass cord with respect to the tire circumferential direction) of [deg] or more and 95 [deg] or less.

  For example, in the configuration of FIG. 1, the carcass layer 13 has a single-layer structure and is continuously spanned between the left and right bead cores 11 and 11. Further, both end portions of the carcass layer 13 are wound and locked outward in the tire width direction so as to wrap the bead core 11 and the bead filler 12.

  However, the present invention is not limited to this, and the carcass layer 13 may include a pair of left and right carcass plies, and have a structure (carcass division structure) separated in the tire width direction by having a split portion in the tread portion. ). Specifically, the ends of the pair of left and right carcass plies on the inner side in the tire radial direction are wound back and locked to the outer side in the tire width direction so as to enclose the bead core 11 and the bead filler 12 on the left and right sides of the tire. Further, the ends of the pair of left and right carcass plies on the outer side in the tire radial direction are disposed separately from each other in the tire width direction in the tread portion center region. In such a carcass division structure, a hollow portion (region having no carcass ply) is formed in the center region of the tread portion. At this time, the tension of the tire in the hollow portion is carried by the belt layer 14, and the rigidity in the left and right sidewall portions is ensured by the left and right carcass layers 13, 13, respectively. As a result, the weight of the tire can be reduced while maintaining the internal pressure holding capability of the tire and the rigidity of the sidewall portion.

  Further, the tan δ value at 60 [° C.] of the coated rubber of the carcass cord is preferably 0.20 or less. Further, the volume resistivity of the carcass cord coat rubber is preferably 1 × 10 ^ 8 [Ω · cm] or more. As a result, the rolling resistance of the tire is reduced. Coated rubber having such a volume resistivity is produced, for example, by using a low heat generation compound with a small amount of carbon. Furthermore, the coat rubber may be configured without using silica, or may be reinforced by containing silica.

  The tan δ value of 60 [° C.] is measured under the conditions of initial strain 10%, amplitude ± 0.5%, and frequency 20 Hz using a viscoelastic spectrometer manufactured by Toyo Seiki Seisakusho.

  The volume resistivity (volume resistivity) is measured based on “Vulcanized rubber and thermoplastic rubber—How to obtain volume resistivity and surface resistivity” defined in JIS K6271. In general, if the volume resistivity is less than 1 × 10 ^ 8 [Ω · cm] or the surface resistivity is less than 1 × 10 ^ 8 [Ω / cm], the member can conduct electricity that can suppress electrostatic charge. It can be said that it has sex.

  The belt layer 14 is formed by laminating a pair of cross belts 141 and 142 and a belt cover 143, and is arranged around the outer periphery of the carcass layer 13. The pair of cross belts 141 and 142 is formed by rolling a plurality of belt cords made of steel or organic fiber material with a coating rubber, and has an absolute value of a belt angle of 20 [deg] or more and 65 [deg] or less. Have. Further, the pair of cross belts 141 and 142 have belt angles with different signs from each other (inclination angle of the fiber direction of the belt cord with respect to the tire circumferential direction), and are laminated so that the fiber directions of the belt cords cross each other. (Cross ply structure). The belt cover 143 is formed by rolling a plurality of cords made of steel or organic fiber material covered with a coat rubber, and has a belt angle of 0 [deg] or more and 10 [deg] or less in absolute value. Further, the belt cover 143 is disposed so as to be laminated on the outer side in the tire radial direction of the cross belts 141 and 142.

  The tread rubber 15 is disposed on the outer circumference in the tire radial direction of the carcass layer 13 and the belt layer 14 to constitute a tread portion of the tire. The tread rubber 15 includes a cap tread 151 and an under tread 152.

  The cap tread 151 is a rubber member that constitutes a tire ground contact surface, and may have a single layer structure (see FIG. 1) or a multilayer structure (not shown). The tan δ value at 60 [° C.] of the cap tread 151 is preferably 0.25 or less. The volume resistivity of the cap tread 151 is preferably in the range of 1 × 10 ^ 8 [Ω · cm] or more, more preferably in the range of 1 × 10 ^ 10 [Ω · cm] or more. More preferably, it is in the range of 1 × 10 ^ 12 [Ω · cm] or more. As a result, the rolling resistance of the tire is reduced. The cap tread 151 having such a volume resistivity is produced by using a low heat generation compound with a small amount of carbon and reinforcing it by increasing the silica content.

  The under tread 152 is a member stacked on the inner side in the tire radial direction of the cap tread 151. The volume resistivity of the undertread 152 is preferably lower than the volume resistivity of the cap tread 151.

  The pair of side wall rubbers 16 and 16 are respectively arranged on the outer side in the tire width direction of the carcass layer 13 to constitute left and right side wall portions. The 60 [° C.] tan δ value of the sidewall rubber 16 is preferably 0.20 or less. The volume resistivity of the sidewall rubber 16 is preferably in the range of 1 × 10 ^ 8 [Ω · cm] or more, and more preferably in the range of 1 × 10 ^ 10 [Ω · cm] or more. More preferably, it is in the range of 1 × 10 ^ 12 [Ω · cm] or more. As a result, the rolling resistance of the tire is reduced. The side wall rubber 16 having such a volume resistivity is produced by using a low heat generation compound with a small amount of carbon and reinforcing it by increasing the silica content.

  The pair of rim cushion rubbers 17, 17 are respectively arranged on the inner side in the tire radial direction of the wound portions of the left and right bead cores 11, 11 and the carcass layer 13, and constitute the contact surfaces of the left and right bead portions with the rim flange portion of the rim R. To do. The volume resistivity of the rim cushion rubber 17 is preferably 1 × 10 ^ 7 [Ω · cm] or less.

  The upper limit value of the volume resistivity of the cap tread 151, the lower limit value of the volume resistivity of the undertread 152, the upper limit value of the volume resistivity of the sidewall rubber 16, and the lower limit value of the volume resistivity of the rim cushion rubber 17 are particularly Although there is no limitation, since these are rubber members, they are physically restricted.

  The inner liner 18 is an air permeation prevention layer that is disposed on the inner surface of the tire and covers the carcass layer 13, suppresses oxidation due to exposure of the carcass layer 13, and prevents leakage of air filled in the tire. The inner liner 18 is composed of, for example, a rubber composition mainly composed of butyl rubber, a thermoplastic resin, a thermoplastic elastomer composition obtained by blending an elastomer component in a thermoplastic resin, and the like. In particular, in the configuration in which the inner liner 18 is made of a thermoplastic resin or a thermoplastic elastomer composition, the inner liner 18 can be made thinner compared to the configuration in which the inner liner 18 is made of butyl rubber, so that the tire weight can be greatly reduced.

  The air permeability coefficient of the inner liner 18 is generally 100 × 10 ^ −12 [cc · cm / cm ^ 2 · sec · cmHg when measured in accordance with JIS K7126-1 at a temperature of 30 ° C. ], Preferably 50 × 10 ^ -12 [cc · cm / cm ^ 2 · sec · cmHg] or less. The volume resistivity of the inner liner 18 is preferably in the range of 1 × 10 ^ 8 [Ω · cm] or more, and is generally preferably 1 × 10 ^ 9 [Ω · cm] or more.

  Examples of the rubber composition containing butyl rubber as a main component include butyl rubber (IIR) and butyl rubber. The butyl rubber is preferably a halogenated butyl rubber such as chlorinated butyl rubber (Cl-IIR) or brominated butyl rubber (Br-IIR).

  Examples of the thermoplastic resin include polyamide-based resins [for example, nylon 6 (N6), nylon 66 (N66), nylon 46 (N46), nylon 11 (N11), nylon 12 (N12), nylon 610 (N610), nylon 612 (N612), nylon 6/66 copolymer (N6 / 66), nylon 6/66/610 copolymer (N6 / 66/610), nylon MXD6, nylon 6T, nylon 9T, nylon 6 / 6T Polymer, nylon 66 / PP copolymer, nylon 66 / PPS copolymer], polyester resin [for example, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), polybutylene terephthalate / tetramethylene Glycol copolymer, PET / P I copolymer, polyarylate (PAR), polybutylene naphthalate (PBN), liquid crystalline polyester, aromatic polyester such as polyoxyalkylene diimide diacid / polybutylene terephthalate copolymer], polynitrile resin (for example, polyacrylonitrile ( PAN), polymethacrylonitrile, acrylonitrile / styrene copolymer (AS), methacrylonitrile / styrene copolymer, methacrylonitrile / styrene / butadiene copolymer], poly (meth) acrylate resin [eg polymethacryl Acid methyl (PMMA), polyethyl methacrylate, ethylene ethyl acrylate copolymer (EEA), ethylene acrylic acid copolymer (EAA), ethylene methyl acrylate resin (EMA)], polyvinyl resin [eg, vinyl acetate EVA), polyvinyl alcohol (PVA), vinyl alcohol / ethylene copolymer (EVOH), polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), vinyl chloride / vinylidene chloride copolymer, vinylidene chloride / methyl acrylate copolymer Coalescence], cellulose resins [eg cellulose acetate, cellulose acetate butyrate], fluorine resins [eg polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), polychlorofluoroethylene (PCTFE), tetrafluoroethylene / ethylene copolymer Combined (ETFE)], imide-based resin [for example, aromatic polyimide (PI)] and the like can be employed.

  Examples of elastomers include diene rubbers and hydrogenated products thereof (eg, NR, IR, epoxidized natural rubber, SBR, BR (high cis BR and low cis BR), NBR, hydrogenated NBR, hydrogenated SBR), olefins Rubber (for example, ethylene propylene rubber (EPDM, EPM), maleic acid modified ethylene propylene rubber (M-EPM)), butyl rubber (IIR), isobutylene and aromatic vinyl or diene monomer copolymer, acrylic rubber (ACM), Ionomer, halogen-containing rubber [for example, brominated product of Br-IIR, Cl-IIR, isobutylene paramethylstyrene copolymer (Br-IPMS), chloroprene rubber (CR), hydrin rubber (CHC, CHR), chlorosulfonated polyethylene (CSM) ), Chlorinated polyethylene (CM) Maleic acid-modified chlorinated polyethylene (M-CM)], silicone rubber [eg methyl vinyl silicone rubber, dimethyl silicone rubber, methyl phenyl vinyl silicone rubber], sulfur-containing rubber [eg polysulfide rubber], fluoro rubber [eg vinylidene fluoride rubber] , Fluorine-containing vinyl ether rubber, tetrafluoroethylene-propylene rubber, fluorine-containing silicon rubber, fluorine-containing phosphazene rubber), thermoplastic elastomers (for example, styrene elastomer, olefin elastomer, polyester elastomer, urethane elastomer, polyamide) Based elastomers] and the like may be employed.

[Charge suppression structure]
In the pneumatic tire, a charge suppression structure using an earth tread is employed to discharge static electricity generated in the vehicle to the road surface when the vehicle is running. The earth tread is a conductive rubber that is embedded in the tread rubber and exposed to the tire ground contact surface. In this charging suppression structure, static electricity from the vehicle is discharged from the belt layer to the road surface via the earth tread, and charging of the vehicle is suppressed.

  On the other hand, in recent years, as described above, in order to reduce tire rolling resistance and improve fuel efficiency, the silica content of rubber compounds constituting cap treads, undertreads, sidewall rubbers, etc. is increased. There is a tendency. Since silica has high insulating properties, when the silica content of the cap tread increases, the volume resistance value of the cap tread increases and the charging suppression performance of the tire decreases.

  Therefore, this pneumatic tire 1 employs the following configuration in order to improve the charge suppression performance.

  FIG. 2 is an explanatory view showing the charge suppression structure of the pneumatic tire shown in FIG. FIG. 3 is an enlarged cross-sectional view showing the earth tread described in FIG. 2. In these drawings, FIG. 2 shows an enlarged cross-sectional view of the tread portion in the tire meridian direction. The earth tread 51 and the conductive portion 52 are hatched.

  As shown in FIG. 1, the pneumatic tire 1 includes an earth tread 51 and a conductive portion 52 as the charge suppression structure 5.

  As shown in FIG. 2, the earth tread 51 is exposed on the tread surface of the tread rubber 15, passes through the cap tread 151 and the undertread 152, and contacts the belt layer 14 (belt cover 143) in a conductive manner. This secures a conductive path from the belt layer 14 to the road surface. The earth tread 51 has an annular structure extending over the entire circumference of the tire, and continuously extends in the tire circumferential direction while exposing a part of the structure on the tread surface. Accordingly, when the tire rolls, the earth tread 51 always contacts the road surface, so that a conductive path from the belt layer 14 to the road surface is always ensured.

  The earth tread 51 is made of a conductive rubber material having a volume resistivity lower than that of the tread rubber 15. Specifically, the volume resistivity of the earth tread 51 is preferably less than 1 × 10 ^ 8 [Ω · cm], and more preferably 1 × 10 ^ 6 [Ω · cm] or less.

  FIG. 4 is an explanatory view showing the arrangement structure of the conductive parts shown in FIG. FIG. 5 is an explanatory view showing a single conductive portion. In these drawings, FIG. 4 schematically shows a sectional view in the radial direction of the belt cover 143 and the conductive portion 52. FIG. 5 shows a stranded wire structure of the conductive portion 52.

  As shown in FIGS. 1 and 2, the conductive portion 52 has an electrical resistivity of less than 1 × 10 ^ 8 [Ω / cm], and extends continuously from at least the bead portion to the belt layer 14. In addition, at least one conductive portion 52 is disposed. Thereby, a conductive path from the bead portion to the belt layer 14 is secured.

  A bead part means the area | region from the measurement point of a rim diameter to 1/3 of tire cross-section height SH.

  The tire cross-section height SH is a half of the difference between the tire outer diameter and the rim diameter, and is measured as a no-load state while applying a specified internal pressure by mounting the tire on a specified rim.

  Here, the prescribed rim refers to “applied rim” prescribed in JATMA, “Design Rim” prescribed in TRA, or “Measuring Rim” prescribed in ETRTO. The specified internal pressure means “maximum air pressure” defined by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO. The specified load means the “maximum load capacity” defined by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “LOAD CAPACITY” defined by ETRTO. However, in JATMA, in the case of tires for passenger cars, the specified internal pressure is air pressure 180 [kPa], and the specified load is 88 [%] of the maximum load capacity.

  In the configuration of FIG. 4, the conductive portion 52 has a linear structure including the conductive linear body 521. The conductive portion 52 may have a stranded wire structure formed by twisting a plurality of linear bodies including at least one conductive linear body 521 (see FIG. 5), or a single wire made of a conductive material. It may be a code (not shown). The configuration in which the conductive portion 52 has a linear structure is preferable in that the rolling resistance of the tire is small as compared with a configuration in which the conductive portion is made of a rubber layer additionally installed on the tire.

  The conductive linear body 521 is a linear body formed by linearly forming a conductive material having an electrical resistivity of less than 1 × 10 ^ 8 [Ω / cm]. Therefore, the conductive linear body 521 means a single fiber made of a conductive material itself, a thread itself, or a cord itself. Therefore, for example, a cord made of metal or carbon fiber, a metal fiber formed by forming a metal such as stainless steel, or the like corresponds to the conductive linear body 521.

  Examples of the stranded wire structure of the conductive portion 52 (see FIG. 5) include, for example, (1) a structure formed by twisting a plurality of carbon fibers, and (2) an electrical resistivity of less than 1 × 10 ^ 8 [Ω / cm]. And a non-conductive linear body 522 having an electrical resistivity of 1 × 10 ^ 8 [Ω / cm] or more is twisted. The stranded wire structure of the linear body is not particularly limited, and an arbitrary one can be adopted.

  As the non-conductive linear body 522 in the above (2), for example, polyester fiber, nylon fiber, or the like can be employed. In particular, the conductive portion 52 is preferably a blended yarn formed by twisting a conductive linear body 521 made of a metal fiber and a non-conductive linear body 522 made of a polyester fiber.

  The electrical resistivity [Ω / cm] is measured by taking a test piece of 3 [cm] or more in the yarn length direction of the fiber and applying a voltage of 500 [V] between the test pieces (between both ends). It is measured using a resistance measuring device “SME-8220” manufactured by Toa Denpa Kogyo Co., Ltd. under the conditions of an environment of 20 ° C. and 20% RH.

  The total fineness of the conductive portion 52 is preferably in the range of 20 [dtex] to 1000 [dtex], and more preferably in the range of 150 [dtex] to 350 [dtex]. By setting the lower limit of the total fineness in the above range, disconnection of the conductive portion 52 during tire manufacture is suppressed. Moreover, the disconnection of the electroconductive part 52 at the time of tire rolling is suppressed by making the upper limit of total fineness into said range.

  The total fineness is measured according to JIS L1017 (chemical fiber tire cord test method 8.3 positive fineness).

  Moreover, it is preferable that the elongation of the electroconductive part 52 exists in the range of 1.0 [%] or more and 70.0 [%] or less. By setting the elongation to 1.0 [%] or more, disconnection of the conductive portion 52 during tire manufacture is suppressed. Further, by setting the elongation to 70.0 [%] or less, disconnection of the conductive portion 52 during tire rolling is suppressed.

  The elongation of the linear body is measured according to JIS L1017 (chemical fiber tire cord test method 8.5 tensile strength and elongation).

  For example, in the configuration of FIG. 1, the conductive portions 52 are respectively disposed in the left and right regions with the tire equatorial plane CL as a boundary. Further, in one region, a plurality of conductive portions 52 are arranged at predetermined intervals in the tire circumferential direction.

  In addition, as shown in FIG. 2, the conductive portion 52 extends continuously in the tire radial direction along the carcass layer 13 and extends from the bead portion to the belt layer 14. Further, the end portion on the inner side in the tire radial direction of the conductive portion 52 is located in the vicinity of the bead core 11 and is in contact with the rim cushion rubber 17. Thereby, a conductive path from the rim fitting surface to the conductive portion 52 via the rim cushion rubber 17 is secured. In addition, an end portion on the outer side in the tire radial direction of the conductive portion 52 extends to a position where it wraps in the tire width direction with respect to the belt layer 14. Thereby, a conductive path from the conductive portion 52 to the belt layer 14 is secured.

  At this time, the lap width La between the belt layer 14 and the conductive portion 52 is preferably in the range of 3 [mm] ≦ La. The upper limit of the wrap width La is not particularly limited, and the conductive portion 52 may extend across the tire equatorial plane CL and straddle the left and right bead portions.

  The lap width La is perpendicular to the conductive portion 52 from the end in the tire width direction outer side of the belt ply 141 having the widest belt ply 141 in the tire meridian direction (belt cord on the outermost side in the tire width direction). Is measured as the surface length of the conductive portion 52 from the perpendicular foot P2 to the end of the conductive portion 52.

  In the configuration of FIG. 1, the conductive portion 52 is a yarn, and is disposed so as to be sandwiched between the carcass layer 13 and the adjacent member. In addition, as shown in FIG. 5, the conductive portion 52 has a conductive linear body 521 having an electrical resistivity of less than 1 × 10 ^ 8 [Ω / cm] and 1 × 10 ^ 8 [Ω / cm] or more. It has a stranded wire structure formed by twisting a non-conductive linear body 522 having electrical resistivity.

  A yarn is a linear body arranged along the surface of the carcass layer 13 (see FIG. 5), and a minute gap is formed between the carcass layer 13 and an adjacent member in a green tire molding process. Has the function of discharging residual air.

  For example, in the configuration of FIG. 1, as shown in FIGS. 2 and 4, the conductive portion 52 is located on the inner peripheral surface side of the carcass layer 13 and is sandwiched between the carcass layer 13, the inner liner 18, and the tie rubber 19. Is arranged.

  At this time, the distance between the conductive portion 52 and the inner liner 18 is preferably 1.0 [mm] or less, and more preferably 0.5 [mm] or less. In particular, in the configuration in which the inner liner 18 is made of a thermoplastic resin, static electricity is generated due to friction during rolling of the tire, and the inner liner 18 is charged. Therefore, by arranging the conductive portion 52 close to the inner liner 18, a conductive path from the inner liner 18 to the conductive portion 52 is appropriately ensured.

  In the above configuration, static electricity generated in the vehicle is discharged from the rim R to the road surface through the rim cushion rubber 17, the conductive portion 52, and the belt layer 14 (and the under tread 152). Thereby, charging of the vehicle due to static electricity is suppressed.

  The rim cushion rubber 17, the coat rubber of the carcass layer 13, and the coat rubber of the belt layer 14 form a conductive path from the rim R to the earth tread 51. For this reason, it is preferable that the volume resistivity of these rubbers is set low. Thereby, the conductive efficiency from the rim R to the earth tread 51 is improved.

  In the configuration of FIG. 2, the end portion on the inner side in the tire radial direction of the conductive portion 52 extends to the vicinity of the bead core 11 and is in contact with the rim cushion rubber 17. Such a configuration is preferable in that a conductive path from the rim fitting surface to the conductive portion 52 via the rim cushion rubber 17 is appropriately secured.

  However, the present invention is not limited thereto, and the end portion of the conductive portion 52 on the inner side in the tire radial direction may extend to the inner side in the radial direction of the bead core 11 (not shown). Further, the end portion on the inner side in the tire radial direction of the conductive portion 52 may be wound and disposed so as to wrap the bead core 11 (not shown). Thereby, the conductivity from the rim fitting surface to the conductive portion 52 is further improved. Further, the end of the conductive portion 52 on the inner side in the tire radial direction may be terminated in the vicinity of the bead filler 12 without contacting the rim cushion rubber 17 (not shown). Even with this configuration, the conductivity from the rim fitting surface to the conductive portion 52 is sufficiently and sufficiently ensured.

[Loose structure of conductive part]
When the tire rolls, the sidewall portion, the end portion of the belt layer 14 and the like are repeatedly bent and deformed. For this reason, as described above, in the configuration in which the conductive portion 52 continuously extends from the bead portion to the belt layer 14, there is a problem that the disconnection of the conductive portion 52 is suppressed and the durability of the conductive portion 52 should be improved. is there.

  Therefore, in this pneumatic tire 1, the conductive portion 52 has the following arrangement structure.

  FIG. 6 is an explanatory view showing a slack structure of the conductive portion shown in FIG. This figure conceptually shows a development view of the arrangement region of the conductive portion 52.

  In FIG. 6, the bead portion is defined as a region from the measurement point of the rim diameter to 1/3 of the tire cross-section height SH (see FIG. 2) as described above. In addition, the boundary between the sidewall portion and the tread portion is generally vague, but here, the reference is based on the perpendicular line extending from the outer end in the tire width direction of the widest belt ply 141 of the belt layer 14 to the carcass layer 13. Define as

  As described above, in the pneumatic tire 1, the conductive portion 52 has a linear structure and continuously extends from the bead portion to the belt layer 14 (see FIG. 2). At this time, as shown in FIG. 6, the conductive portion 52 has a region where the conductive portion 52 is arranged with a large slack. In such a configuration, when the tire is repeatedly bent and deformed when the tire rolls, the tension acting on the conductive portion 52 is relaxed. Thereby, disconnection of the conductive part 52 is prevented, and durability of the conductive part 52 is improved.

  Specifically, as shown in FIG. 6, an area of 30 [%] of the tire cross-section height SH around the tire maximum width position P1 is defined. This region is defined on the arrangement surface of the conductive portion 52 (in FIG. 2, the inner peripheral surface of the carcass layer 13). At this time, the extension length La1 of the conductive portion 52 and the peripheral length Lp1 of the carcass layer 13 in this region have a relationship of 1.15 ≦ La1 / Lp1 (reference numerals omitted in the drawing). Moreover, it is preferable that the ratio La1 / Lp1 has a relationship of 1.30 ≦ La1 / Lp1. The upper limit of the ratio La1 / Lp1 is not particularly limited. For example, when La1 / Lp1 ≦ 3.80, the adhesiveness between the conductive portion 52 and the peripheral rubber can be appropriately ensured.

  The tire maximum width position P1 refers to the maximum width position of the tire cross-sectional width specified by JATMA. Note that the tire cross-sectional width is measured as a no-load state while applying a specified internal pressure by mounting the tire on a specified rim.

  The extension length of the conductive part 52 is the road length of the conductive part 52, and is measured as a no-load state while applying a specified internal pressure by mounting a tire on a specified rim. The extension length becomes longer as the slackness of the conductive portion 52 is larger.

  The peripheral length of the carcass layer 13 is the surface length of the carcass layer 13 (circumferential surface facing the conductive portion 52) in a cross-sectional view in the tire meridian direction, and the tire is attached to a specified rim to apply a specified internal pressure. And measured as an unloaded condition.

  Further, an area of 15 [%] of the belt width Wb is defined centering on the foot P2 of the perpendicular line extending from the end in the tire width direction of the widest belt ply 141 of the belt layer 14 to the carcass layer 13. This region is defined on the arrangement surface of the conductive portion 52 (in FIG. 2, the inner peripheral surface of the carcass layer 13). At this time, the extension length La2 of the conductive portion 52 in this region and the peripheral length Lp2 of the carcass layer 13 have a relationship of 1.15 ≦ La2 / Lp2 (not shown in the drawing). The ratio La2 / Lp2 preferably has a relationship of 1.30 ≦ La2 / Lp2. The upper limit of the ratio La2 / Lp2 is not particularly limited. For example, when La2 / Lp2 ≦ 3.80, the adhesiveness between the conductive portion 52 and the peripheral rubber can be appropriately ensured.

  The belt width Wb is the distance in the tire width direction between the left and right end portions (belt cords on the outermost side in the tire width direction) of the belt ply 141, and is loaded with the tire on the specified rim and filled with the specified internal pressure. Measured in state.

  Further, an area of 10 [%] of the tire cross-section height SH around the end P3 on the outer side in the tire radial direction of the bead filler 12 is defined. This region is defined on the arrangement surface of the conductive portion 52 (in FIG. 2, the inner peripheral surface of the carcass layer 13). At this time, the extension length La3 of the conductive portion 52 in this region and the peripheral length Lp3 of the carcass layer 13 have a relationship of 1.15 ≦ La3 / Lp3 (reference numerals omitted in the drawing). The ratio La3 / Lp3 preferably has a relationship of 1.30 ≦ La3 / Lp3. The upper limit of the ratio La3 / Lp3 is not particularly limited. For example, when La3 / Lp3 ≦ 3.80, the adhesiveness between the conductive portion 52 and the peripheral rubber can be appropriately ensured.

  Further, the position is lowered to the carcass layer 13 from the position P4 which is 1/3 of the tire cross-section height SH with respect to the measurement point of the rim diameter and the end of the widest belt ply 141 of the belt layer 14 in the tire width direction. An area between the perpendicular foot P2 is defined. This region is defined on the arrangement surface of the conductive portion 52 (in FIG. 2, the inner peripheral surface of the carcass layer 13). At this time, it is preferable that the extension length La4 of the conductive portion 52 in this region and the peripheral length Lp4 of the carcass layer 13 have a relationship of 1.15 ≦ La4 / Lp4. The upper limit of the ratio La4 / Lp4 is not particularly limited. For example, when La4 / Lp4 ≦ 3.80, the adhesiveness between the conductive portion 52 and the peripheral rubber can be appropriately ensured.

  On the other hand, as shown in FIG. 6, the conductive portion 52 has a region in which the conductive portion 52 is arranged in a substantially straight line (with a straight line or a small slack).

  Specifically, an area of 15 [%] of the tire cross-section height SH around the radially outer side surface (bead top) of the bead core 11 is defined. This region is defined on the arrangement surface of the conductive portion 52 (in FIG. 2, the inner peripheral surface of the carcass layer 13). At this time, the extension length La5 of the conductive portion 52 in this region and the peripheral length Lp5 of the carcass layer 13 have a relationship of 1.00 ≦ La5 / Lp5 ≦ 1.10.

  The radially outer surface of the bead core 11 is defined as a measurement point of the outer shape of a bundle of bead wires.

  Further, an area of 10 [%] of the belt width Wb around the tire equator plane CL is defined. This region is defined on the arrangement surface of the conductive portion 52 (in FIG. 2, the inner peripheral surface of the carcass layer 13). At this time, the extension length La6 of the conductive portion 52 and the belt width Wb in this region have a relationship of 1.00 ≦ La6 / Wb ≦ 1.10.

  For example, in the configuration of FIG. 6, one conductive portion 52 has a wavy shape or a zigzag shape that continuously extends from the bead portion to the tread portion (belt layer 14) while having an amplitude in the tire circumferential direction. ing. Moreover, the electroconductive part 52 has a multi-step slack structure by changing the amplitude of a wavy shape in the middle of extension. Thereby, extension length La1-La6 of the electroconductive part 52 in each above-mentioned area | region is optimized.

  Specifically, first, a continuous portion including the end portion P3 of the bead filler 12 in the tire radial direction in FIG. 2, the entire sidewall portion (tire maximum width position P1), and the end portion of the belt layer 14 (perpendicular foot P2). In this area, the wavy shape of the conductive portion 52 has a large amplitude. Thereby, the extending lengths La1 to La4 of the conductive portions 52 in each of the above-described regions are optimized. In such a configuration, the conductive portion 52 is greatly slackened and disposed in a region where it is easily bent and deformed when the tire rolls, so that the tension acting on the conductive portion 52 that is a linear structure is relaxed. Thereby, the disconnection of the electroconductive part 52 is suppressed appropriately.

  On the other hand, the wavy shape of the conductive portion 52 has a small amplitude in a region deviating from the above region, that is, in the peripheral region of the bead core 11 and the region of the tread portion (region where the belt layer 14 is disposed). For this reason, the slackness of the conductive part 52 is small, and the conductive part 52 extends substantially linearly. Thereby, the extending lengths La5 and La6 of the conductive portion 52 in the region are set short. That is, if the overall looseness of the conductive part 52 becomes large, the conductive part 52 becomes difficult to break and the durability of the conductive part 52 is improved, but the electrical resistance of the conductive part 52 increases. Therefore, by setting the extended lengths La5 and La6 of the conductive portion 52 in the predetermined region to be short, it is possible to achieve both durability of the conductive portion 52 and reduction of electric resistance.

  Further, as shown in FIG. 6, in the configuration in which the conductive portion 52 has a wavy shape extending in the tire radial direction while having an amplitude in the tire circumferential direction, the tire between the wavy-shaped maximum amplitude position and the tire maximum width position P <b> 1. The radial distance D is preferably in the range of 15 [mm] ≦ D. Thereby, the fracture | rupture of the electroconductive part 52 in the tire maximum width position P1 resulting from repeated bending deformation of a tire can be suppressed effectively.

  In the configuration of FIG. 6, the period of the wavy shape of the conductive portion 52 is substantially constant over the entire arrangement region of the conductive portion 52. However, the present invention is not limited to this, and the wave-like period of the conductive portion 52 may partially change (not shown). In such a configuration, the extension length of the conductive portion 52 can be increased by shortening the period of the wavy shape of the conductive portion 52 in the predetermined region. Thereby, extension length La1-La6 of the electroconductive part 52 can be adjusted efficiently.

[Modification]
FIG. 7 is an explanatory view showing a modification of the slack structure of the conductive portion shown in FIG. This figure conceptually shows a development view of the arrangement region of the conductive portion 52.

  In the configuration of FIG. 6, the conductive portion 52 has a wavy shape that continuously extends from the bead portion to the tread portion (belt layer 14) while having an amplitude in the tire circumferential direction, and the wavy shape of the conductive portion 52. The shape has a large amplitude in a continuous region including the end portion P3 on the outer side in the tire radial direction of the bead filler 12, the entire sidewall portion (tire maximum width position P1), and the end portion position P2 of the belt layer 14. Yes. Such a configuration is preferable in that the extending length of the entire conductive portion 52 can be increased.

  In contrast, in the configuration of FIG. 7, the wavy shape of the conductive portion 52 has a large amplitude in a continuous region including the tire maximum width position P1 to the end position P2 of the belt layer 14, and the tire maximum width position. In the region from P1 to bead core 11, it has a small amplitude.

  That is, a region between the tire maximum width position P1 and the leg of the perpendicular line extending from the outer end in the tire width direction of the widest belt ply 141 of the belt layer 14 to the carcass layer is referred to as a radially outer region. A region between the tire maximum width position and the position of 1/3 of the tire cross-section height with respect to the measurement point of the rim diameter is referred to as a radially inner region. At this time, the ratio La_out / Lp_out between the extension length La_out of the conductive portion 52 in the radially outer region and the peripheral length Lp_out of the carcass layer 13 is equal to the extension length La_in of the conductive portion 52 in the radially inner region and the carcass. It is larger than the ratio La_in / Lp_in with the peripheral length Lp_in of the layer 13. Further, the ratio La_out / Lp_out in the radially outer region is preferably set in a range of 1.30 ≦ La_out / Lp_out. Further, the ratio La_in / Lp_in in the radially inner region is preferably set in a range of 1.00 ≦ La_in / Lp_in ≦ 1.20, and is set in a range of 1.00 ≦ La_in / Lp_in ≦ 1.10. More preferably.

  In the configuration of FIG. 7, the extending length of the conductive portion 52 is set to be long in the tire radial direction outer region where contact with a curb or the like is likely to occur. Thereby, the fracture | rupture of the electroconductive part 52 is suppressed effectively. On the other hand, the extending length of the conductive portion 52 is set to be short in the tire radial direction inner region. Thereby, it is possible to achieve both durability of the conductive portion 52 and reduction of electric resistance.

  8-12 is explanatory drawing which shows the modification of the slack structure of the electroconductive part described in FIG. These drawings conceptually show development views of the arrangement region of the conductive portion 52.

  6 and 7, the conductive portion 52 has a wave shape or a zigzag shape extending in the tire radial direction while having an amplitude in the tire circumferential direction. Such a configuration is preferable in that the extension lengths La1 to La6 of the conductive portions 52 in each of the above-described regions can be easily adjusted by changing the amplitude of the wavy shape in the middle of the extension.

  However, the present invention is not limited to this, and as shown in FIG. 8, the conductive portion 52 may have an arc-shaped portion that protrudes in the tire circumferential direction in the development view of the arrangement region of the conductive portion 52. Specifically, the conductive portion 52 has a tire circumference such that the extending lengths La1 and La2 of the conductive portion 52 are large in each region centered on the tire maximum width position P1 and the end position P2 of the belt layer 14. It may bulge and extend in an arc shape in the direction.

  Moreover, as shown in FIG. 9, in the development view of the arrangement region of the conductive portion 52, the conductive portion 52 may extend in the tire radial direction while turning in a coil shape. Such a configuration is preferable in that the extending lengths La1 to La4 of the conductive portions 52 in each region can be efficiently increased compared to the configuration of FIG.

  6 to 9, the conductive portion 52 as a whole extends substantially parallel to the tire radial direction. And the extension length of the electroconductive part 52 is ensured because the electroconductive part 52 curves in the tire circumferential direction.

  However, the present invention is not limited to this, as shown in FIG. 10, in the development view of the arrangement region of the conductive portion 52, a portion where the conductive portion 52 linearly extends in the tire radial direction while being inclined in the tire circumferential direction. You may have. In such a configuration, the extending lengths La1 to La6 of the conductive portion 52 in each region can be adjusted by adjusting the angle θ between the extending direction of the conductive portion 52 and the tire radial direction. Moreover, the installation process of the electroconductive part 52 at the time of tire shaping | molding is easy compared with the structure of FIG.

  Further, as shown in FIGS. 11 and 12, in the developed view of the arrangement region of the conductive portion 52, the conductive portion 52 is curved into an S shape (FIG. 11) or a wavy shape (FIG. 12), and the tire circumference You may have the part extended in a tire radial direction, inclining in a direction. In such a configuration, the extension lengths La1 to La4 of the conductive portions 52 in each region can be easily adjusted by adjusting the amplitude of the S-shape or the wavy shape. Moreover, the extension length of the electroconductive part 52 can be increased compared with the structure of FIG.

  13-16 is explanatory drawing which shows the modification of the pneumatic tire described in FIG. These drawings show modified examples of the arrangement structure of the conductive portions 52.

  In the configuration of FIG. 1, as shown in FIGS. 2 and 4, the conductive portion 52 is disposed on the inner periphery of the carcass layer 13 and is sandwiched between the carcass layer 13, the inner liner 18, and the tie rubber 19. . In such a configuration, the distance between the inner liner 18 and the conductive portion 52 can be reduced. Specifically, the distance between the conductive portion 52 and the inner liner 18 can be set to 1.0 [mm] or less. This is particularly preferable in that the static electricity generated in the inner liner 18 can be efficiently released to the conductive portion 52 in the configuration in which the inner liner 18 is made of a thermoplastic resin.

  On the other hand, in the configuration of FIG. 13, the conductive portion 52 is disposed on the outer periphery of the carcass layer 13. Specifically, the conductive portion 52 is a yarn for discharging residual air in the green tire molding process, and a stranded wire structure formed by twisting a plurality of linear bodies including conductive linear bodies (FIG. 5). See). Further, the conductive portion 52 is disposed along the outer peripheral surface of the carcass layer 13 (see FIG. 13) and extends from the bead portion to the belt layer 14. Further, the end portion on the outer side in the tire radial direction of the conductive portion 52 extends to a position where it wraps on the belt layer 14, and the belt layer 14 (the belt ply 141 located on the innermost side in the radial direction; see FIG. 2) and the carcass layer 13 It is sandwiched between.

  The end portion of the conductive portion 52 on the inner side in the tire radial direction may be located on the inner side in the tire width direction of the bead core 11 or the bead filler 12, may be located on the inner side in the radial direction of the bead core 11, or the bead core 11. May be rolled up together with the carcass layer 13 so as to wrap up (not shown).

  In the configuration of FIG. 14, the conductive portion 52 is a member different from the yarn, and a part or all of the conductive portion 52 is disposed separately from the carcass layer 13. Specifically, the conductive portion 52 is disposed between the bead core 11, the bead filler 12, and the sidewall rubber 16, and extends from the bead portion to the belt layer 14. Further, the end portion on the outer side in the tire radial direction of the conductive portion 52 extends to a position where it wraps on the belt layer 14, and the belt layer 14 (the belt ply 141 located on the innermost side in the radial direction; see FIG. 2) and the carcass layer 13 It is sandwiched between.

  Further, in the configuration of FIG. 14, the end portion in the tire radial direction of the conductive portion 52 is sandwiched between the rolled-up portion of the carcass layer 13 and the sidewall rubber 16 and the rim cushion rubber 17 and extends to the vicinity of the bead core 11. doing. As described above, the contact between the conductive portion 52 and the rim cushion rubber 17 improves the conductivity from the rim fitting surface to the conductive portion 52.

  In the configuration of FIG. 14, the end portion of the conductive portion 52 on the inner side in the tire radial direction may be sandwiched between the bead core 11 and the bead filler 12 and the winding portion of the carcass layer 13 (not shown). Even with this configuration, a conductive path from the rim cushion rubber 17 to the conductive portion 52 through the coat rubber of the carcass layer 13 is secured.

  In the configuration of FIG. 15, the conductive portion 52 is disposed so as to be exposed on the tire inner peripheral surface. Specifically, the conductive portion 52 is disposed closer to the tire lumen than the inner liner 18 and the tie rubber 19 and is exposed on the tire inner peripheral surface. Further, the conductive portion 52 extends from the bead portion to the belt layer 14 along the surface of the inner liner 18.

  In the configuration of FIG. 15, the end portion on the inner side in the tire radial direction of the conductive portion 52 extends to the lower layer of the rim cushion rubber 17 together with the inner liner 18 and the tie rubber 19, and the rim cushion rubber 17 and the carcass layer 13 It is sandwiched between them. Further, when the conductive portion 52 comes into contact with the rim cushion rubber 17, conductivity from the rim fitting surface to the conductive portion 52 is enhanced. At this time, the end portion on the inner side in the tire radial direction of the conductive portion 52 may be located on the inner side in the tire width direction of the bead core 11 or the bead filler 12 (see FIG. 15), or located on the inner side in the radial direction of the bead core 11. Alternatively, it may be wound up along the carcass layer 13 so as to wrap the bead core 11 (not shown).

  In the configuration of FIG. 1, the conductive portions 52 are respectively disposed in the left and right regions with the tire equatorial plane CL as a boundary. Further, the end portion on the outer side in the tire radial direction of the conductive portion 52 extends from the bead portion to a position where the belt portion 14 wraps, and terminates without exceeding the tire equatorial plane CL.

  However, the present invention is not limited to this, and the conductive portion 52 may be disposed only in one region having the tire equatorial plane CL as a boundary (not shown). As shown in FIG. You may arrange | position over the perimeter of a direction.

  In FIG. 3, the earth tread 51 is employed as a discharge structure from the belt layer 14 (or the under tread 152) to the tread rubber 15 tread surface. However, the present invention is not limited to this, and other known discharge structures may be employed.

[effect]
As described above, the pneumatic tire 1 includes a pair of bead cores 11 and 11 and at least one carcass layer 13 spanned between the pair of bead cores 11 and 11 with a continuous or divided tread portion. A pair of belt layers 14 disposed on the outer side in the tire radial direction of the carcass layer 13, a tread rubber 15 disposed on the outer side in the tire radial direction of the belt layer 14, and a pair disposed on the outer side in the tire width direction of the carcass layer 13. Side wall rubbers 16 and 16 (see FIG. 1). In addition, the pneumatic tire 1 includes a conductive portion 52 that continuously extends from at least the bead portion to the belt layer 14. Further, the conductive portion 52 has a conductive linear body 521 formed by linearly forming a conductive material having an electrical resistivity of less than 1 × 10 ^ 8 [Ω / cm] (see FIG. 5). Further, the extension length La of the conductive portion 52 in a predetermined region and the peripheral length Lp of the carcass layer 13 have a relationship of 1.15 ≦ La / Lp (see FIG. 6).

  In such a configuration, (1) the conductive path from the bead portion to the belt layer 14 is ensured by the conductive portion 52, so that there is an advantage that the charging suppression performance of the tire is effectively improved.

  (2) Since the conductive linear body 521 of the conductive portion 52 is formed by linearly forming a conductive material having an electrical resistivity of less than 1 × 10 ^ 8 [Ω / cm], the tire manufacturing process and tire use A decrease in the conductive performance of the conductive portion 52 in the state is suppressed. Thereby, there exists an advantage by which the electrical charging suppression performance of a tire is ensured appropriately. For example, in a configuration in which the conductive portion is formed by coating a non-conductive linear body with a conductive material, the coating is easily peeled off due to heat and distortion in the tire manufacturing process and the tire use state. For this reason, there exists a possibility that the electroconductivity of a conductive part may fall, and it is not preferable. In particular, when the inner liner 18 is made of a thermoplastic resin or a thermoplastic elastomer composition obtained by blending an elastomer component in a thermoplastic resin, the gauge of the inner liner 18 is thin. The embedded conductive portion 52 (see, for example, FIG. 2 and FIG. 13) becomes high temperature. For this reason, the configuration in which the conductive portion is formed by coating a non-conductive linear body with a conductive material is not preferable because the coating is particularly easy to peel off.

  Further, (3) in a predetermined region, the ratio La / Lp between the extension length La of the conductive portion 52 and the peripheral length Lp of the carcass layer 13 is set large, so that the conductive portion 52 has a large slack. Be placed. In such a configuration, when the tire is repeatedly bent and deformed when the tire rolls, the tension acting on the conductive portion 52 is relaxed. Thereby, disconnection of the conductive part 52 is prevented, and there is an advantage that durability of the conductive part is improved.

  Further, in this pneumatic tire 1, the extension length La1 of the conductive portion 52 and the peripheral length Lp1 of the carcass layer 13 in the region of 30 [%] of the tire cross-section height SH centering on the tire maximum width position P1 Has a relationship of 1.15 ≦ La1 / Lp1 (see FIGS. 2 and 6). In particular, in the region near the tire maximum width position P1, large repeated bending deformation acts when the tire rolls. Therefore, in this region, the ratio La1 / Lp1 between the extension length La1 of the conductive portion 52 and the peripheral length Lp1 of the carcass layer 13 is set large, so that the disconnection of the conductive portion 52 is effectively prevented. There are advantages.

  Further, in this pneumatic tire 1, 15 [%] of the belt width Wb centering on the foot P2 of the perpendicular line descending from the outer end in the tire width direction of the widest belt ply 141 of the belt layer 14 to the carcass layer 13. In this region, the extension length La2 of the conductive portion 52 and the peripheral length Lp2 of the carcass layer 13 have a relationship of 1.15 ≦ La2 / Lp2 (see FIGS. 2 and 6). In particular, in the region near the end position P2 of the belt layer 14, large repeated bending deformation acts when the tire rolls. Therefore, in this region, the ratio La2 / Lp2 between the extension length La2 of the conductive portion 52 and the peripheral length Lp2 of the carcass layer 13 is set large, so that the disconnection of the conductive portion 52 is effectively prevented. There are advantages.

  Further, the pneumatic tire 1 includes a bead filler 12 disposed on the outer side in the tire radial direction of the bead core 11 (see FIG. 1). Further, the extension length La3 of the conductive portion 52 and the peripheral length Lp3 of the carcass layer 13 in the region of 10 [%] of the tire cross-section height SH around the end portion P3 on the outer side in the tire radial direction of the bead filler 12 However, it has a relationship of 1.15 <= La3 / Lp3 (refer FIG. 2 and FIG. 6). In particular, in the region of the end portion P3 of the bead filler 12, large repeated bending deformation acts when the tire rolls. Therefore, in this region, the ratio La3 / Lp3 between the extension length La3 of the conductive portion 52 and the peripheral length Lp3 of the carcass layer 13 is set large, so that the disconnection of the conductive portion 52 is effectively prevented. There are advantages.

  In the pneumatic tire 1, the position P4 that is 1/3 of the tire cross-sectional height with respect to the measurement point of the rim diameter, and the outermost end in the tire width direction of the widest belt ply 141 of the belt layer 14. The extension length La4 of the conductive portion 52 and the peripheral length Lp4 of the carcass layer 13 in a region between the perpendicular foot P2 drawn down on the carcass layer 13 have a relationship of 1.15 ≦ La4 / Lp4 (FIG. 2 and FIG. 6). In such a configuration, since the ratio La4 / Lp4 between the extension length La4 of the conductive portion 52 and the peripheral length Lp4 of the carcass layer 13 is set to be large in the entire sidewall portion, the disconnection of the conductive portion 52 is caused. There is an advantage of being effectively prevented.

  Further, in this pneumatic tire 1, the extension length La5 of the conductive portion 52 and the peripheral length of the carcass layer 13 in the region of 15 [%] of the tire cross-section height SH centering on the radially outer surface of the bead core 11. Lp5 has a relationship of 1.00 ≦ La5 / Lp5 ≦ 1.10 (see FIGS. 2 and 6). With such a configuration, the extension length La5 of the conductive portion 52 in the predetermined region of the bead portion is set to be short, so that there is an advantage that both the durability of the conductive portion 52 and the reduction of electric resistance can be achieved.

  Further, in the pneumatic tire 1, the extension length La6 of the conductive portion 52 and the belt width Wb in the region of 10% of the belt width Wb centered on the tire equatorial plane CL are 1.00 ≦ La6 / The relation of Wb ≦ 1.10 is established (see FIGS. 2 and 6). With such a configuration, the extension length La6 of the conductive portion 52 in the predetermined region of the tread portion is set to be short, so that there is an advantage that both the durability of the conductive portion 52 and the reduction of electric resistance can be achieved.

  Further, in this pneumatic tire 1, a region between the tire maximum width position P1 and the foot P2 of the perpendicular line descending to the carcass layer 13 from the outer end in the tire width direction of the widest belt ply 141 of the belt layer 14 is defined. When the area between the tire maximum width position P1 and the position P4 that is 1/3 of the tire cross-section height SH with reference to the measurement point of the rim diameter is referred to as a radially inner area, The ratio La_out / Lp_out between the extending length La_out of the conductive portion 52 in the outer region in the direction and the peripheral length Lp_out of the carcass layer 13 is equal to the extension length La_in of the conductive portion 52 in the radially inner region and the peripheral portion of the carcass layer 13. It is larger than the ratio La_in / Lp_in with the length Lp_in (see FIG. 7). In such a configuration, since the extending length of the conductive portion 52 is set to be long in the tire radial direction outer region where contact with a curbstone or the like is likely to occur, there is an advantage that breakage of the conductive portion 52 is effectively suppressed. . In addition, since the extending length of the conductive portion 52 is set to be short in the tire radial direction inner region, there is an advantage that both the durability of the conductive portion 52 and the reduction of the electric resistance can be achieved.

  Moreover, in this pneumatic tire 1, in the development view of the arrangement region of the conductive portion 52, the conductive portion 52 has a wave shape (FIGS. 6 and 7), an arc shape (FIG. 8), or a coil shape (FIG. 9). Arranged loosely. Thereby, there exists an advantage which can adjust the extension length of the electroconductive part 52 efficiently.

  Moreover, in this pneumatic tire 1, the electroconductive part 52 has the curved shape curved in the tire circumferential direction (refer FIGS. 6-8). Further, a distance D in the tire radial direction between the top of the curved shape and the tire maximum width position P1 is in a range of 15 [mm] ≦ D. Thereby, there exists an advantage which can suppress effectively the disconnection of the electroconductive part 52 resulting from the repeated bending deformation at the time of tire rolling.

  Moreover, in this pneumatic tire 1, the electroconductive part 52 is inclined and arrange | positioned in the tire circumferential direction (refer FIGS. 10-12). Thereby, there exists an advantage which can ensure appropriately the extension length of the electroconductive part 52 in each area | region.

  Moreover, in this pneumatic tire 1, the electroconductive part 52 twists the several linear body containing the at least 1 conductive linear body 521 (refer FIG. 5). In such a configuration, since the conductive portion 52 has a stranded wire structure, it is advantageous for repeated fatigue and elongation as compared with a configuration in which the conductive portion is a single wire, so that the durability of the conductive linear body 521 is improved. There are advantages.

  Moreover, in this pneumatic tire 1, the conductive portion 52 has a conductive linear body 521 having an electrical resistivity of less than 1 × 10 ^ 8 [Ω / cm] and 1 × 10 ^ 8 [Ω / cm] or more. A non-conductive linear body 522 having electrical resistivity is twisted together (see FIG. 5). Thereby, for example, there is an advantage that the strength, heat resistance, and dimensional stability of the conductive portion 52 can be appropriately ensured by supplementing the weak points of the conductive linear body 521 with the non-conductive linear body 522.

  Moreover, in this pneumatic tire 1, the conductive linear body 521 is a metal fiber (especially stainless fiber), and the non-conductive linear body 522 is an organic fiber (especially polyester fiber) (refer FIG. 5). . Thereby, there exists an advantage which can ensure intensity | strength, heat resistance, and dimensional stability appropriately.

  Further, in this pneumatic tire 1, the conductive portion 52 has the carcass layer 13 and adjacent members (for example, the inner liner 18 and the tie rubber 19 in FIGS. 2 and 4. In FIG. 13, the belt layer 14 and the sidewall rubber 16, etc. )). In such a configuration, since the conductive portion 52 is embedded in the tire, there is an advantage that it is possible to suppress a situation where the conductive portion is disconnected at the time of manufacturing the tire or using the tire, compared to a configuration in which the conductive portion is exposed on the tire surface.

  Moreover, in this pneumatic tire 1, the total fineness of the electroconductive part 52 is 20 [dtex] or more and 1000 [dtex] or less. Thereby, there exists an advantage by which the total fineness of the electroconductive part 52 is optimized. That is, when the total fineness is 20 [dtex] or more, disconnection of the conductive portion 52 during tire manufacture is suppressed. Moreover, since the total fineness is 1000 [dtex] or less, disconnection of the conductive portion 52 during rolling of the tire is suppressed.

  Moreover, in this pneumatic tire 1, the elongation percentage of the electroconductive part 52 is 1.0 [%] or more and 70.0 [%] or less. Thereby, there exists an advantage by which the elongation rate of the electroconductive part 52 is optimized. That is, when the elongation is 1.0 [%] or more, disconnection of the conductive portion 52 at the time of tire manufacture is suppressed. Moreover, when the elongation percentage is 70.0 [%] or less, disconnection of the conductive portion 52 during tire rolling is suppressed.

  Further, in the pneumatic tire 1, the tread rubber 15 includes a cap tread 151 that constitutes a tire contact surface, and an under tread 152 that is laminated on the inner side in the tire radial direction of the cap tread 151 (see FIG. 1). Further, the tan δ value at 60 [° C.] of the cap tread 151 is 0.25 or less, and the volume resistivity of the cap tread 151 is in the range of 1 × 10 ^ 8 [Ω · cm] or more. In such a configuration, for example, by increasing the silica content of the cap tread 151 to obtain the above configuration, there is an advantage that the rolling resistance of the tire is reduced.

  Further, in this pneumatic tire 1, the tan δ value at 60 [° C.] of the sidewall rubber 16 is 0.25 or less, and the volume resistivity of the sidewall rubber 16 is 1 × 10 ^ 8 [Ω · cm] or more. It is in the range. In such a configuration, for example, by increasing the silica content of the sidewall rubber 16 to achieve the above configuration, there is an advantage that the rolling resistance of the tire is reduced.

  The pneumatic tire 1 includes an inner liner 18 disposed on the inner peripheral surface of the carcass layer. The inner liner 18 is made of a thermoplastic resin or a thermoplastic elastomer composition obtained by blending an elastomer component in a thermoplastic resin. In such a configuration, there is an advantage that the air permeability of the inner liner 18 can be reduced compared to a configuration in which the inner liner 18 is made of butyl rubber, and there is an advantage that the tire weight can be reduced and the rolling resistance of the tire can be reduced.

  FIG. 17 is a chart showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention.

  In this performance test, evaluations on (1) low rolling resistance performance and (2) charge suppression performance (electric resistance value) were performed on a plurality of different test tires. In this performance test, a test tire having a tire size of 195 / 65R15 91H is manufactured and used.

  (1) In the evaluation on the low rolling resistance performance, an indoor drum type tire rolling resistance tester with a drum diameter of 1707 [mm] is used, and the rolling resistance of the tire is measured according to the measurement method of JATMA Y / B 2012 version. Measured. This evaluation is performed by index evaluation using the conventional example as a reference (100). The larger the value, the smaller the rolling resistance, which is preferable.

  (2) In the evaluation relating to the charge suppression performance, the electrical resistance [Ω] of the tire is measured using an ADVANTEST R8340A ultra high resistance meter based on the measurement conditions specified by JATMA. Further, the electrical resistance is measured when the tire is new and after running under a predetermined condition. The electric resistance after running is an indoor drum type tire rolling resistance tester with a drum diameter of 1707 [mm]. The test tire is assembled to an applicable rim specified by JATMA, and the test tire has an air pressure of 200 [kPa] and JATMA specified. It is measured after running for 60 minutes at a speed of 81 [km / h], giving 80% of the maximum load. In this evaluation, the smaller the numerical value, the better the discharge property, which is preferable.

  The test tires of Examples 1 to 11 are based on the configuration shown in FIGS. 1 and 2 and include an earth tread 51 and a conductive portion 52 including a conductive linear body. The conductive portion 52 is a “carbon fiber” obtained by twisting a plurality of carbon fibers or a “mixed yarn” obtained by twisting polyester fibers and stainless steel fibers. The “linear electrical resistivity [Ω / cm] of the conductive portion” indicates the resistivity of the conductive portion 52 that is a stranded wire. The conductive portion 52 is disposed between the carcass layer 13, the inner liner 18, and the tie rubber 19, and continuously extends from the bead portion to the belt layer. Further, in Example 1, the conductive portion 52 extends with a uniform wavy shape from the bead portion to the tread portion while having an amplitude in the tire circumferential direction. Moreover, in Examples 4-11, it has the slack structure of FIG. 6 or FIG. 7, and a "wave-like part" extended in the tire radial direction while making an amplitude in the tire circumferential direction, and substantially linear in the tire radial direction. It has a “straight line portion” that extends. The conductive portion 52 is a “carbon fiber” obtained by twisting a plurality of carbon fibers or a “mixed yarn” obtained by twisting polyester fibers and stainless steel fibers. The “linear electrical resistivity [Ω / cm] of the conductive portion” indicates the resistivity of the conductive portion 52 that is a stranded wire.

  In the test tire of Conventional Example 1, the cap tread has a conductive property and does not include an earth tread. In addition, a single-wire conductive portion made of carbon fiber is disposed so as to continuously extend from the bead portion to the belt layer. The conductive portion extends linearly in the tire radial direction. In the test tire of Conventional Example 2, in the configuration of Example 1, the amplitude of the wavy shape of the conductive part is small, and the conductive part extends substantially linearly from the bead part to the tread part.

  As shown in the test results, it can be seen that in the test tires of Examples 1 to 11, the low rolling resistance performance and the charge suppression performance of the tire are improved.

  1: Pneumatic tire, 5: Antistatic structure, 51: Earth red, 52: Conductive part, 521: Conductive linear body, 522: Nonconductive linear body, 11: Bead core, 12: Bead filler, 13: Carcass layer , 14: belt layer, 141-143: belt ply, 15: tread rubber, 151: cap tread, 152: under tread, 16: sidewall rubber, 17: rim cushion rubber, 18: inner liner, 19: tie rubber, 20 : Chefa

Claims (17)

A pair of bead cores, at least one carcass layer spanned between the pair of bead cores in a continuous or tread portion, and a belt layer disposed on the outer side in the tire radial direction of the carcass layer; A pneumatic tire comprising a tread rubber disposed on the outer side in the tire radial direction of the belt layer, and a pair of sidewall rubbers disposed on the outer side in the tire width direction of the carcass layer,
Comprising at least a conductive portion extending continuously from the bead portion to the belt layer;
The conductive portion is, 1 × 10 ^ 8 have at [Ω / cm] of less than comprising a conductive material having an electrical resistivity by forming a line-shaped conductive wire-like body,
The extension of the conductive portion standing length La and periphery length Lp of the carcass layer, have a relationship of 1.15 ≦ La / Lp in a predetermined region, and,
An extension length La5 of the conductive portion and a peripheral length Lp5 of the carcass layer in a region of 15% of the tire cross-section height SH centering on the radially outer surface of the bead core are 1.00 ≦ La5. A pneumatic tire having a relationship of /Lp5≦1.10 .   The extension length La1 of the conductive portion and the peripheral length Lp1 of the carcass layer in the region of 30 [%] of the tire cross-sectional height centered on the tire maximum width position is 1.15 ≦ La1 / Lp1. The pneumatic tire according to claim 1 having. The extension of the conductive portion in the region of 15% of the belt width Wb centered on the leg of the perpendicular line extending from the outer end in the tire width direction of the widest belt ply of the belt layer to the outer peripheral surface of the carcass layer The pneumatic tire according to claim 1 or 2, wherein a length La2 and a peripheral length Lp2 of the carcass layer have a relationship of 1.15 ≦ La2 / Lp2. Comprising a bead filler disposed on the outer side in the tire radial direction of the bead core; and
The extension length La3 of the conductive portion and the peripheral length Lp3 of the carcass layer in a region of 10 [%] of the tire cross-sectional height centered on the tire radial outer end of the bead filler are: The pneumatic tire according to any one of claims 1 to 3, which has a relationship of 15? La3 / Lp3. The position of 1/3 of the tire cross-section height with respect to the measurement point of the rim diameter, and the perpendicular line extending from the outer end in the tire width direction of the widest belt ply of the belt layer to the outer peripheral surface of the carcass layer The extension length La4 of the conductive portion in the region between the legs and the peripheral length Lp4 of the carcass layer have a relationship of 1.15 ≦ La4 / Lp4. The described pneumatic tire. The extension length La6 of the conductive portion and the belt width Wb in a region of 10% of the belt width Wb centered on the tire equator plane have a relationship of 1.00 ≦ La6 / Wb ≦ 1.10. The pneumatic tire according to any one of Items 1 to 5 . It called the widest belt ply of the region radially outer region between the end portion in the tire width direction outside the perpendicular foot drawn down to an outer peripheral surface of the carcass layer of the belt layer and the tire maximum width position, the tire outermost When a region between the large position and the position of 1/3 of the tire cross-section height with respect to the measurement point of the rim diameter is referred to as a radially inner region,
The ratio La_out / Lp_out between the extension length La_out of the conductive portion in the radially outer region and the peripheral length Lp_out of the carcass layer is equal to the extension length La_in of the conductive portion in the radially inner region and the carcass layer. The pneumatic tire according to any one of claims 1 to 6 , wherein the pneumatic tire is larger than a ratio La_in / Lp_in to the peripheral length Lp_in. The pneumatic tire according to any one of claims 1 to 7 , wherein the conductive portion is arranged in a wave-like shape, an arc shape, or a coil shape in a development view of the arrangement region of the conductive portion. The conductive portion has a curved shape curved in the tire circumferential direction, and a distance D in the tire radial direction between the top of the curved shape and the tire maximum width position is in a range of 15 [mm] ≦ D. Item 10. The pneumatic tire according to any one of Items 1 to 8 . The pneumatic tire according to any one of claims 1 to 9 , wherein the conductive portion is disposed to be inclined in a tire circumferential direction. The pneumatic tire according to any one of claims 1 to 10 , wherein the conductive portion is formed by twisting a plurality of linear bodies including at least one conductive linear body. The conductive portion having an electrical resistivity of less than 1 × 10 ^ 8 [Ω / cm] and a non-conductive linear shape having an electrical resistivity of 1 × 10 ^ 8 [Ω / cm] or more. The pneumatic tire according to any one of claims 1 to 10 , which is formed by twisting a body. The pneumatic tire according to claim 12 , wherein the conductive linear body is a metal fiber, and the non-conductive linear body is an organic fiber. The pneumatic tire according to any one of claims 1 to 13 , wherein the conductive portion is disposed between the carcass layer and an adjacent member. A pair of bead cores, at least one carcass layer spanned between the pair of bead cores in a continuous or tread portion, and a belt layer disposed on the outer side in the tire radial direction of the carcass layer; A pneumatic tire comprising a tread rubber disposed on the outer side in the tire radial direction of the belt layer, and a pair of sidewall rubbers disposed on the outer side in the tire width direction of the carcass layer,
Comprising at least a conductive portion extending continuously from the bead portion to the belt layer;
The conductive portion is, 1 × 10 ^ 8 have at [Ω / cm] of less than comprising a conductive material having an electrical resistivity by forming a line-shaped conductive wire-like body,
The extension of the conductive portion standing length La and periphery length Lp of the carcass layer, have a relationship of 1.15 ≦ La / Lp in a predetermined region, and,
The extension length La6 of the conductive portion in the region of 10% of the belt width Wb centered on the tire equator plane and the belt width Wb have a relationship of 1.00 ≦ La6 / Wb ≦ 1.10. Pneumatic tire characterized by. A pair of bead cores, at least one carcass layer spanned between the pair of bead cores in a continuous or tread portion, and a belt layer disposed on the outer side in the tire radial direction of the carcass layer; A pneumatic tire comprising a tread rubber disposed on the outer side in the tire radial direction of the belt layer, and a pair of sidewall rubbers disposed on the outer side in the tire width direction of the carcass layer,
Comprising at least a conductive portion extending continuously from the bead portion to the belt layer;
The conductive portion is, 1 × 10 ^ 8 have at [Ω / cm] of less than comprising a conductive material having an electrical resistivity by forming a line-shaped conductive wire-like body,
The extension of the conductive portion standing length La and periphery length Lp of the carcass layer, have a relationship of 1.15 ≦ La / Lp in a predetermined region, and,
The area between the tire maximum width position and the end of the belt belt ply having the widest belt ply in the tire width direction on the outer leg of the carcass layer is called the radial outer area. When a region between the large position and the position of 1/3 of the tire cross-section height with respect to the measurement point of the rim diameter is referred to as a radially inner region,
The ratio La_out / Lp_out between the extension length La_out of the conductive portion in the radially outer region and the peripheral length Lp_out of the carcass layer is equal to the extension length La_in of the conductive portion in the radially inner region and the carcass layer. A pneumatic tire characterized by being larger than a ratio La_in / Lp_in to the peripheral length Lp_in . A pair of bead cores, at least one carcass layer spanned between the pair of bead cores in a continuous or tread portion, and a belt layer disposed on the outer side in the tire radial direction of the carcass layer; A pneumatic tire comprising a tread rubber disposed on the outer side in the tire radial direction of the belt layer, and a pair of sidewall rubbers disposed on the outer side in the tire width direction of the carcass layer,
Comprising at least a conductive portion extending continuously from the bead portion to the belt layer;
The conductive portion is, 1 × 10 ^ 8 have at [Ω / cm] of less than comprising a conductive material having an electrical resistivity by forming a line-shaped conductive wire-like body,
The extension of the conductive portion standing length La and periphery length Lp of the carcass layer, have a relationship of 1.15 ≦ La / Lp in a predetermined region, and,
The conductive portion has a curved shape curved in the tire circumferential direction, and the distance D in the tire radial direction between the top of the curved shape and the tire maximum width position is in a range of 15 [mm] ≦ D. Pneumatic tire characterized by.

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