JP6357764B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire capable of improving the charge suppression performance.

  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 layer extending from the bead portion to the belt layer in order to improve the charge suppression performance. As conventional pneumatic tires adopting such a configuration, for example, techniques described in Patent Documents 1 and 2 are known.

JP2013-49382A JP2012-131100A

  An object of the present invention is to provide a pneumatic tire capable of improving the charge suppression performance.

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 having a volume resistivity of 1 × 10 ^ 9 [Ω · cm] or more and an inner liner disposed on an inner peripheral surface of the carcass layer, wherein the belt layer extends from at least a bead portion. The surface that extends continuously while being exposed to the inner peripheral surface of the tire, and the surface exposed to the inner peripheral surface of the tire is less than 1 × 10 ^ 8 [Ω / mm ^ 2] E Bei conductive portion having anti-ratio, the tread rubber has a cap tread constituting the tire contact surface, an under tread laminated in the tire radial direction inner side of the cap tread, and, of the cap tread The tan δ value at 60 [° C.] is 0.25 or less, and the volume specific resistivity of the cap tread is in the range of 1 × 10 ^ 8 [Ω · cm] or more .
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 belt layer disposed on the outer side in the tire direction, a tread rubber disposed on the outer side in the tire radial direction of the belt layer, a pair of sidewall rubbers disposed on the outer side in the tire width direction of the carcass layer, and 1 × 10 ^ A pneumatic tire having a volume resistivity of 9 [Ω · cm] or more and having an inner liner disposed on an inner peripheral surface of the carcass layer, and at least an inner peripheral surface of the tire from a bead portion to the belt layer The conductive layer has a surface resistivity of less than 1 × 10 ^ 8 [Ω / mm ^ 2] at the portion exposed to the tire inner peripheral surface while being continuously exposed. And the tread rubber has a cap tread that constitutes a tire contact surface, and an under tread that is laminated inside the cap tread in the tire radial direction, and less than 1 × 10 ^ 8 [Ω · cm] And an earth tread which penetrates at least the cap tread and is exposed to the tire ground contact surface.
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 belt layer disposed on the outer side in the tire direction, a tread rubber disposed on the outer side in the tire radial direction of the belt layer, a pair of sidewall rubbers disposed on the outer side in the tire width direction of the carcass layer, and 1 × 10 ^ A pneumatic tire having a volume resistivity of 9 [Ω · cm] or more and having an inner liner disposed on an inner peripheral surface of the carcass layer, and at least an inner peripheral surface of the tire from a bead portion to the belt layer The conductive layer has a surface resistivity of less than 1 × 10 ^ 8 [Ω / mm ^ 2] at the portion exposed to the tire inner peripheral surface while being continuously exposed. The sidewall rubber has a tan δ value of 60 [° C.] of 0.20 or less, and the volume resistivity of the sidewall rubber is in the range of 1 × 10 ^ 8 [Ω · cm] or more. It is characterized by being.

  In the pneumatic tire according to the present invention, a conductive path from the bead portion to the belt layer is secured by the conductive portion, so that there is an advantage that the antistatic performance of the tire is effectively 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 explanatory view showing the charge suppression structure of the pneumatic tire shown in FIG. FIG. 4 is an explanatory view showing the charge suppression structure of the pneumatic tire shown in FIG. FIG. 5 is an explanatory diagram showing the charge suppression structure of the pneumatic tire shown in FIG. 1. FIG. 6 is an explanatory view showing a modified example of the pneumatic tire shown in FIG. 1. FIG. 7 is an explanatory view showing a modified example of the pneumatic tire shown in FIG. 1. FIG. 8 is an explanatory view showing a modified example of the pneumatic tire shown in FIG. 1. FIG. 9 is an explanatory view illustrating a modified example of the pneumatic tire depicted in FIG. 1. FIG. 10 is an explanatory view showing a modified example of the pneumatic tire shown in FIG. 1. FIG. 11 is an explanatory view showing a modified example of the pneumatic tire shown in FIG. 1. FIG. 12 is an explanatory diagram illustrating a modification of the pneumatic tire depicted in FIG. 1. 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 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. And a pair of side wall rubbers 16 and 16, a pair of rim cushion rubbers 17 and 17, and an inner liner 18 (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 circumference in the tire radial direction of the pair of bead cores 11 and 11 to constitute a bead portion.

  The carcass layer 13 is bridged in a toroidal shape between the left and right bead cores 11 and 11 to form a tire skeleton. 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. The carcass layer 13 is formed by rolling 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 has an absolute value of 80 [deg]. A carcass angle of 95 [deg] or less (inclination angle in the fiber direction of the carcass cord with respect to the tire circumferential direction).

  In the configuration of FIG. 1, the carcass layer 13 has a structure that continuously extends between the bead cores 11 on the left and right sides of the tire.

  However, the present invention is not limited to this, and the carcass layer 13 may have a structure separated in the tire width direction by a pair of left and right carcass plies, a so-called divided carcass structure (not shown). Specifically, the tire radial direction inner ends of the pair of left and right carcass plies are wound and locked to the outer side in the tire width direction so as to wrap the bead core 11 and the bead filler 12 on the left and right sides of the tire, The ends of the pair of left and right carcass plies on the outer side in the tire radial direction are arranged separately from each other in the tire width direction in the tread portion center region.

  In such a divided carcass 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 carcass 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 and 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.

  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 55 [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. Further, the specific volume resistivity of the cap tread 151 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. 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. Such a configuration is preferable because the tan δ value at 60 [° C.] is reduced and the rolling resistance of the tire is reduced.

  The tan δ value of 60 [° C.] is measured with a viscoelasticity spectrometer manufactured by Toyo Seiki Seisakusho Co., Ltd., with an initial strain of 10 [%], an amplitude of ± 0.5 [%], and a frequency of 20 [Hz]. .

  The volume resistivity is measured based on “vulcanized rubber and thermoplastic rubber—how to obtain volume resistivity and surface resistivity” defined in JIS-K6271. Generally, when the resistivity is in a range of less than 1 × 10 ^ 8 [Ω / mm ^ 2], it can be said that the member has conductivity capable of suppressing electrostatic charging.

  The under tread 152 is a member stacked on the inner side in the tire radial direction 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 resistivity of the sidewall rubber 16 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. The sidewall rubber 16 having such a resistivity is produced by using a low heat generation compound with a small amount of carbon and reinforcing it by increasing the silica content. Such a configuration is preferable because the tan δ value at 60 [° C.] is reduced and the rolling resistance of the tire is reduced.

  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 resistivity of the rim cushion rubber 17 is preferably less than 1 × 10 ^ 8 [Ω · cm].

  The upper limit value of the resistivity of the cap tread 151, the lower limit value of the resistivity of the undertread 152, the upper limit value of the resistivity of the sidewall rubber 16, and the lower limit value of the resistivity of the rim cushion rubber 17 are not particularly limited. Since these are rubber members, they are physically restricted.

  The inner liner 18 is an air permeation preventive 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 inner liner 18 generally has an air of 100 × 10 ^ -12 [cc · cm / cm ^ 2 · sec · cmHg] or less when measured according to JIS K7126-1 at a temperature of 30 [° C.]. A transmission coefficient is required. The resistivity of the inner liner 18 is generally 1 × 10 ^ 9 [Ω · cm] or more.

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

  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 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, 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 characteristics, when the silica content of the cap tread increases, the 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.

  2-5 is explanatory drawing which shows the electrical charging suppression structure of the pneumatic tire described in FIG. In these drawings, FIG. 2 shows a cross-sectional view in the tire meridian direction in one side region with the tire equatorial plane CL as a boundary. FIG. 3 shows an enlarged cross-sectional view of the earth tread 51. FIG. 4 shows a laminated structure of the conductive portion 52, the carcass layer 13, the inner liner 18, and the tie rubber 19. FIG. 5 schematically shows an arrangement region of the conductive portions 52 in the tire circumferential direction. In these drawings, the conductive portion 52 is 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 FIGS. 2 and 3, the earth tread 51 is exposed on the tread surface of the tread rubber 15, penetrates the cap tread 151 and the undertread 152, and comes into conductive contact with the belt layer 14 (belt cover 143). 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 resistivity lower than that of the tread rubber 15. Specifically, the 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.

  As shown in FIGS. 1 and 2, the conductive portion 52 extends continuously from at least the bead portion to the belt layer 14. 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.

  Further, as shown in FIGS. 4 and 5, the conductive portion 52 is disposed so as to be exposed on the tire inner peripheral surface. That is, the conductive portion 52 is on the innermost surface of the tire and is exposed on the surface of the tire lumen portion. In such a configuration, the conductive portion 52 is exposed to the tire inner peripheral surface, so that the influence of adjacent members is reduced and electricity can be passed effectively. In addition, since the conductive portion 52 is colored, it can be easily recognized whether or not the conductive portion 52 extends without interruption in a predetermined region from the bead portion to the belt layer 14.

  In addition, the conductive portion 52 has a surface resistivity of less than 1 × 10 ^ 8 [Ω / mm ^ 2] at a portion exposed on the tire inner peripheral surface. The surface resistivity of the conductive portion 52 is more preferably in the range of less than 1 × 10 ^ 6 [Ω / mm ^ 2]. Thereby, the electroconductivity of the electroconductive part 52 is ensured. The lower limit of the surface resistivity is not particularly limited and is preferably as small as possible.

  The surface resistivity is measured based on “vulcanized rubber and thermoplastic rubber—how to obtain volume resistivity and surface resistivity” defined in JIS-K6271.

  For example, in the configuration of FIG. 1, as shown in FIG. 2, the conductive portion 52 extends continuously along the inner peripheral surface of the inner liner 18 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 on the side of the bead filler 12 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 of the belt ply 141 of the widest belt ply 141 in the tire width direction in a cross-sectional view in the tire meridian direction, and the conductive portion 52 extends from the foot of the perpendicular. Measured as the surface length of the conductive portion 52 up to the end of the.

  As shown in FIG. 4, the conductive portion 52 is composed of a conductive layer disposed on a part of the inner surface of the inner liner 18. Such a conductive layer may be, for example, a sheet-like conductive rubber laminated on the surface of the inner liner 18, or may be a conductive paint or conductive paste applied or deposited on the surface of the inner liner 18.

  In addition, when the conductive portion 52 is a conductive layer as shown in FIG. 4, the minimum value of the gauge Ga (thickness, not shown) of the conductive layer is in the range of 0.01 [mm] ≦ Ga. preferable. Thereby, the electroconductivity of the electroconductive part 52 is securable appropriately. The upper limit of the gauge Ga is not particularly limited, but if it is too large, the tire weight increases, which is not preferable.

  Moreover, as shown in FIG. 5, the electroconductive part 52 is arrange | positioned only in a part of tire peripheral direction, and is extended in the tire radial direction. At this time, the width Wa in the tire circumferential direction of the conductive portion 52 and the circumferential length Lp (not shown) of the sidewall portion at the tire maximum width position P preferably have a relationship of Wa / Lp ≦ 0.10. It is more preferable to have a relationship of Wa / Lp ≦ 0.05, and it is even more preferable to have a relationship of Wa / Lp ≦ 0.01. Thereby, the rolling resistance of a tire can be reduced. The lower limit of the width Wa of the conductive portion 52 is not particularly limited. For example, in the case of a tire having a tire size of 195 / 65R15, it is preferable that the width is in the range of 150 [mm] ≦ Wa. Thereby, the electroconductivity of the electroconductive part 52 is securable appropriately.

  The tire maximum width position P 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.

  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 inner liner 18 and the tie rubber 19, 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 resistivity of these rubbers is set low. Thereby, the conductive efficiency from the rim R to the earth tread 51 is improved.

[Modification]
6 and 7 are explanatory views showing modifications of the pneumatic tire depicted in FIG. This figure shows an enlarged cross-sectional view of the bead portion.

  In the configuration of FIG. 1, as described above, the conductive portion 52 extends continuously from the bead portion to the belt layer 14 (see FIG. 2). At this time, the end portion of the conductive portion 52 on the inner side in the tire radial direction is on the outer side in the tire radial direction with respect to the bead core 11, and is in contact with the rim cushion rubber 17 at this position. Thereby, a conductive path from the rim R to the conductive portion 52 via the rim cushion rubber 17 is formed. In such a configuration, it is preferable in that the charge suppressing action can be efficiently obtained by setting the resistivity of the rim cushion rubber 17 low.

  However, the present invention is not limited to this, and the end of the conductive portion 52 on the inner side in the tire radial direction may contact the finishing chafer 20 (not shown). Further, for example, as shown in FIG. 6, the conductive portion 52 may extend beyond the bead toe to the rim contact surface of the bead portion. Furthermore, as shown in FIG. 7, the conductive portion 52 may be wound up along the bead portion and extend to the outside in the tire width direction of the bead portion. In these configurations, the conductive portion 52 extends to the rim contact surface of the bead portion, whereby a direct conductive path from the rim R to the conductive portion 52 is formed. As a result, the conductivity efficiency is improved, and the charge suppressing action is further improved.

  FIG. 8 is an explanatory view showing a modified example of the pneumatic tire shown in FIG. 1. The figure shows a laminated structure of the carcass layer 13, the belt layer 14, and the inner liner 18.

  In the configuration of FIG. 1, as described above, the conductive portion 52 is a conductive layer and is formed on the inner peripheral surface of the inner liner 18 (see FIG. 4). Such a configuration is preferable in that the conductive portion 52 can be easily formed on an existing tire, for example, by application or sticking.

  However, the present invention is not limited to this, and as shown in FIG. 8, part or all of the inner liner 18 may also serve as the conductive portion 52. For example, a part or all of the inner liner 18 is made of conductive rubber and covers the inner peripheral surface of the carcass layer 13 to function as an inner liner, while extending from the bead portion to the belt layer 14 as the conductive portion 52. May function.

  Further, the conductive portion 52 may be formed by a release agent applied to the inner peripheral surface of the inner liner 18 (not shown). For example, the conductive portion 52 can be formed on the inner peripheral surface of the inner liner 18 by applying a release agent to the inner peripheral surface of the green tire prior to the tire vulcanization molding step.

  Such a release agent is produced by blending a filler having excellent electrical conductivity such as carbon, carbon nanotube, graphene, acetylene black, ketjen black, and the like. Moreover, it is preferable that a mold release agent contains carbon black whose DBP (Di-butyl phthalate) is 100 [cm ^ 3 / g] or more. The release agent preferably includes carbon fibers having an average length of 0.5 [μm] to 50 [μm] and an average diameter of 0.5 [nm] to 500 [nm]. Moreover, it is preferable that a mold release agent contains a graphene.

  9-11 is explanatory drawing which shows the modification of the pneumatic tire described in FIG. These drawings schematically show the arrangement region of the conductive portions 52 in the tire circumferential direction.

  In the configuration of FIG. 1, as described above, the conductive portion 52 is disposed only in a part in the tire circumferential direction and extends in the tire radial direction. In such a configuration, since the arrangement region of the conductive portion 52 is narrow, the tire weight is reduced, and the rolling resistance of the tire is preferable.

  However, the present invention is not limited to this, and as shown in FIG. 9, the conductive portion 52 may be arranged uniformly over the entire tire circumference. Moreover, as shown in FIG. 10 or FIG. 11, the some electroconductive part 52 may be arrange | positioned radially or windmill-like, leaving a predetermined space | interval in a tire peripheral direction. In the configuration of FIG. 10 or FIG. 11, it is preferable that the total width Wa of the plurality of conductive portions 52 in the tire circumferential direction has a relationship of Wa / Lp ≦ 0.10.

  Moreover, in the structure of FIG. 1, the electroconductive part 52 is arrange | positioned at the area | region on the tire right and left, respectively. However, the present invention is not limited to this, and the conductive portion 52 may be disposed only in one side region of the tire (not shown).

  FIG. 12 is an explanatory diagram illustrating a modification of the pneumatic tire depicted in FIG. 1. This figure shows an arrangement structure of the conductive portions 52 in a sectional view in the tire meridian direction.

  In the configuration of FIGS. 1 and 2, the conductive portion 52 extends from the bead portion to the belt layer 14 and terminates near the end portion of the belt layer 14. In such a configuration, since the arrangement region of the conductive portion 52 is narrow, the tire weight is reduced, and the rolling resistance of the tire is preferable.

  However, the present invention is not limited thereto, and as shown in FIG. 12, the conductive portion 52 may be disposed over the entire circumference in the tire width direction. At this time, the single conductive portion 52 may continuously extend from one bead portion to the other bead portion (see FIG. 12), or the plurality of conductive portions 52 wrap around each other. However, it may be continuously arranged from one bead part to the other bead part (not shown). For example, the pair of left and right conductive portions 52 may extend from the bead portions on the left and right sides of the tire along the inner liner 18 and be connected to each other at any position where the belt layer 14 is wrapped.

  13 and 14 are explanatory views showing a modification of the pneumatic tire shown in FIG. These drawings show enlarged sectional views of the earth tread 51.

  In the configuration of FIG. 1, as shown in FIG. 3, the earth tread 51 is exposed on the tread rubber tread surface in a cross-sectional view in the tire meridian direction, penetrates the cap tread 151 and the under tread 152, and the belt layer 14. It contacts the belt cover 143 (outermost layer) in a conductive manner. The earth tread 51 has a straight shape. In such a configuration, a conductive path from the belt layer 14 having a low resistivity to the tread surface of the tread rubber 15 through the earth tread 51 is ensured.

  In contrast, in the configuration of FIG. 13, in the configuration of FIG. 3, the earth tread 51 penetrates only the cap tread 151 and contacts the undertread 152. Even in such a configuration, by setting the resistivity of the undertread 152 to be low, a charge suppressing action can be efficiently obtained.

  Further, in the configuration of FIG. 14, in the configuration of FIG. 3, the earth tread 51 has a shape widened from the tread surface of the tread rubber 15 toward the belt layer 14, and the contact surface with the belt layer 14 is increased. In this configuration, the contact area between the earth tread 51 and the belt layer 14 is stabilized while suppressing the exposed area of the earth tread 51 on the tread surface as compared with the configuration in which the earth tread 51 has a straight shape (see FIG. 3). Can be secured. Thereby, the conductivity from the belt layer 14 to the earth tread 51 is improved.

  3, 13, and 14, the earth tread 51 is employed as a discharge structure from the belt layer 14 (or the undertread 152) to the tread rubber 15 tread. 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 rubbers 16 and 16 and an inner liner 18 disposed on the inner peripheral surface of the carcass layer 13 (see FIG. 1). The pneumatic tire 1 continuously extends from the bead portion to the belt layer 14 while being exposed on the tire inner peripheral surface, and 1 × 10 ^ 8 [Ω / The conductive portion 52 having a surface resistivity less than mm ^ 2] is provided (see FIG. 2).

  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.

  Further, (2) since the conductive portion 52 is exposed on the inner circumferential surface of the tire (it is on the innermost surface of the tire), there is an advantage that the influence of adjacent members is reduced and electricity can be passed effectively.

  Moreover, in this pneumatic tire 1, the electroconductive part 52 is an electroconductive layer arrange | positioned at the inner peripheral surface of the inner liner 18 (refer FIG. 2 and FIG. 4). Such a configuration has an advantage that the conductive portion 52 can be easily formed on an existing tire by, for example, coating.

  Moreover, in this pneumatic tire 1, a part or all of the inner liner 18 also serves as the conductive portion 52 (see FIG. 8). Such a configuration has an advantage that the rolling resistance of the tire can be reduced as compared with a configuration in which a conductive layer is provided on the inner liner 18 (see FIG. 4).

  In the pneumatic tire 1, the conductive portion 52 is a release agent applied to the inner peripheral surface of the inner liner 18. Such a configuration has an advantage that the rolling resistance of the tire can be reduced as compared with a configuration in which a conductive layer is provided on the inner liner 18 (see FIG. 4).

  In the pneumatic tire 1, the lap width La between the belt layer 14 and the conductive portion 52 is in the range of 3 [mm] ≦ La (see FIG. 2). Thereby, there exists an advantage by which the electroconductivity from the electroconductive part 52 to the belt layer 14 is ensured appropriately.

  Further, in this pneumatic tire 1, the width Wa of the conductive portion 52 in the tire circumferential direction and the tire circumferential length Lp at the tire maximum width position P (see FIG. 2) have a relationship of Wa / Lp ≦ 0.10. (See FIG. 5). In such a configuration, there is an advantage that deterioration of rolling resistance due to the installation of the conductive part 52 can be suppressed by reducing the installation area of the conductive part 52.

  Moreover, in this pneumatic tire 1, the inner liner 18 is made of a thermoplastic elastomer 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.

  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.

  Moreover, in this pneumatic tire 1, the tread rubber 15 has the cap tread 151 which comprises a tire ground-contact surface, and the under tread 152 laminated | stacked inside the tire radial direction of the cap tread 151, and is 1x10. An earth tread 51 having a resistivity of less than ^ 8 [Ω · cm] and at least penetrating the cap tread 151 and exposed to the tire contact surface (see FIGS. 1 to 3). Thereby, there is an advantage that a conductive path from the belt layer 14 (or the undertread 152) to the ground surface of the tread rubber 15 is secured.

  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]. It is in the above 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.

  FIG. 15 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) charging suppression performance (electric resistance value) and (2) low rolling resistance performance 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 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. In this evaluation, the smaller the numerical value, the better the discharge property, which is preferable.

  (2) In the evaluation on the low rolling resistance performance, an indoor drum type tire rolling resistance tester having 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.

  In the test tires of Examples 1 to 12, in the configuration of FIGS. 1 to 5, the conductive portion 52 is made of a rubber sheet having conductivity, and is laminated on the inner peripheral surface of the inner liner 18, and the bead portion. To the belt layer 14. Further, in the test tires of Examples 1 to 5, in the configuration of FIG. 1, the inner liner 18 is made of butyl rubber. On the other hand, in the test tires of Examples 6 to 12, the inner liner 18 is made of a thermoplastic resin. Moreover, the test tires of Examples 1 to 7 do not include the earth tread 51 in the configuration of FIG. On the other hand, the test tires of Examples 8 to 12 have the configuration of FIG.

  In the test tires of Example 13 and Example 14, in the configuration of FIG. 1, the conductive portion 52 is made of a release agent applied to the inner peripheral surface of the inner liner 18. In Example 13, the release agent was blended in a weight ratio of water 100, surfactant 0.1, talc 100, mica 20, silicon emulsion 1, carbon nanotube (Showa Denko VGCF-G) 2 Become. In Example 14, the release agent is obtained by adding graphene generated by heat-treating the graph guard to the formulation of Example 13.

  In the test tire of the conventional example, in the configuration of Example 1, the conductive portion 52 is made of a conductive rubber sheet, and is inserted between the carcass layer 13 and the sidewall rubber 16, and the belt layer 14 extends from the bead portion. Extend to. Further, the inner liner 18 is made of butyl rubber and does not include the earth tread 51.

  As shown in the test results, it can be seen that in the test tires of Examples 1 to 14, the tire charge suppression performance and low rolling resistance performance are improved.

  1: Pneumatic tire, 5: Antistatic structure, 51: Earth red, 52: Conductive part, 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: Side wall rubber, 17: Rim cushion rubber, 18: Inner liner, 19: Tie rubber, 20: Finishing chafer

Claims (10)

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 tread rubber disposed on the outer side in the tire radial direction of the belt layer, a pair of sidewall rubbers disposed on the outer side in the tire width direction of the carcass layer, and a volume specific resistance of 1 × 10 ^ 9 [Ω · cm] or more A pneumatic tire having a rate and an inner liner disposed on an inner peripheral surface of the carcass layer,
The surface resistance extends at least from the bead portion to the belt layer while being exposed to the tire inner peripheral surface, and the surface resistance is less than 1 × 10 ^ 8 [Ω / mm ^ 2] at the portion exposed to the tire inner peripheral surface. e Bei conductive portion having a rate,
The tread rubber has a cap tread that constitutes a tire contact surface, and an under tread that is laminated on the inner side in the tire radial direction of the cap tread; and
The cap tread has a tan δ value at 60 [° C.] of 0.25 or less, and the cap tread has a volume resistivity of 1 × 10 ^ 8 [Ω · cm] or more. Enter tire.   The pneumatic tire according to claim 1, wherein the conductive portion is a conductive layer disposed on an inner peripheral surface of the inner liner.   The pneumatic tire according to claim 1, wherein the conductive portion is a release agent applied to an inner peripheral surface of the inner liner.   The pneumatic tire according to any one of claims 1 to 3, wherein a lap width La between the belt layer and the conductive portion is in a range of 3 [mm]? La.   The pneumatic according to any one of claims 1 to 4, wherein a width Wa of the conductive portion in the tire circumferential direction and a tire circumferential length Lp at a tire maximum width position have a relationship of Wa / Lp ≦ 0.10. tire.   The pneumatic tire according to any one of claims 1 to 5, wherein the inner liner is made of a thermoplastic resin or a thermoplastic elastomer composition obtained by blending an elastomer component in a thermoplastic resin. The tread rubber has a cap tread that constitutes a tire contact surface, and an under tread that is laminated on the inner side in the tire radial direction of the cap tread; and
Which has a 1 × 10 ^ 8 [Ω · cm] below the resistivity, air according to any one of claims 1 to 6 comprising a ground tread exposed to at least the tire ground contact surface through the cap tread Enter tire. The sidewall rubber has a tan δ value of 60 [° C] of 0.20 or less, and the volume resistivity of the sidewall rubber is in a range of 1 × 10 ^ 8 [Ω · cm] or more. The pneumatic tire according to any one of 7 above. 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 tread rubber disposed on the outer side in the tire radial direction of the belt layer, a pair of sidewall rubbers disposed on the outer side in the tire width direction of the carcass layer, and a volume specific resistance of 1 × 10 ^ 9 [Ω · cm] or more A pneumatic tire having a rate and an inner liner disposed on an inner peripheral surface of the carcass layer,
The surface resistance extends at least from the bead portion to the belt layer while being exposed to the tire inner peripheral surface, and the surface resistance is less than 1 × 10 ^ 8 [Ω / mm ^ 2] at the portion exposed to the tire inner peripheral surface. e Bei conductive portion having a rate,
The tread rubber has a cap tread that constitutes a tire contact surface, and an under tread that is laminated on the inner side in the tire radial direction of the cap tread; and
A pneumatic tire comprising an earth tread having a resistivity of less than 1 × 10 ^ 8 [Ω · cm] and at least penetrating through the cap tread and exposed to a tire contact surface . 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 tread rubber disposed on the outer side in the tire radial direction of the belt layer, a pair of sidewall rubbers disposed on the outer side in the tire width direction of the carcass layer, and a volume specific resistance of 1 × 10 ^ 9 [Ω · cm] or more A pneumatic tire having a rate and an inner liner disposed on an inner peripheral surface of the carcass layer,
The surface resistance extends at least from the bead portion to the belt layer while being exposed to the tire inner peripheral surface, and the surface resistance is less than 1 × 10 ^ 8 [Ω / mm ^ 2] at the portion exposed to the tire inner peripheral surface. e Bei conductive portion having a rate, and,
The sidewall rubber has a tan δ value of 60 [° C.] of 0.20 or less, and a volume resistivity of the sidewall rubber is in a range of 1 × 10 ^ 8 [Ω · cm] or more. Pneumatic tires.

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