JP6303487B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire including a charge suppression structure for discharging static electricity generated in a vehicle to the road surface when the vehicle is traveling.

  In recent pneumatic tires, an antistatic 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 is provided with the electroconductive part extended to the area | region from a bead part to a belt layer, in order to improve an electrical charging suppression performance. As conventional pneumatic tires employing such a configuration, for example, techniques described in Patent Documents 1 to 3 are known.

  Further, a carcass layer of a recent pneumatic tire has a woven structure composed of a plurality of carcass cords (warp yarns) arranged in parallel to each other and weft yarns woven across these carcass cords. ing. As a conventional pneumatic tire employing such a carcass layer, for example, a technique described in Patent Document 4 is known. In addition, the technique of patent document 4 makes it a solution subject to prevent generation | occurrence | production of the malfunction on the basis of generation | occurrence | production of the static electricity at the time of passing through the manufacturing process of a rubber product. For this reason, the technique of patent document 4 has a different problem from the patent documents 1 to 3 described above.

JP2012-131100A JP 2009-154608 A JP 2009-40331 A JP 2008-13879 A

  An object of the present invention is to provide a pneumatic tire having a charge suppression structure for discharging static electricity generated in a vehicle to the road surface when the vehicle is traveling.

In order to achieve the above object, a pneumatic tire according to the present invention includes a pair of bead cores, a carcass layer that spans the bead core, a belt layer that is disposed on a radially outer side of the carcass layer, and the belt layer. Air having a tread rubber disposed on the outer side in the tire radial direction of the tire, a pair of sidewall rubbers disposed on the outer side in the tire width direction of the carcass layer, and an inner liner disposed on the inner peripheral surface of the carcass layer. The carcass layer includes a plurality of carcass cords made of an organic fiber material and arranged in parallel to each other, and at least one weft woven across the carcass cord. And the weft has a volume resistivity of less than 1 × 10 ^ 8 [Ω · cm], and at least from the bead portion to the belt layer It is characterized by extending continuously so as to be conductive.

  In the pneumatic tire according to the present invention, since the conductive path from the bead portion to the belt layer is secured by the weft of the carcass layer, 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 diagram showing the charge suppression structure of the pneumatic tire shown in FIG. 1. FIG. 7 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 periphery in the tire radial direction of the pair of bead cores 11 and 11 to reinforce the 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 an organic fiber material (for example, aramid, nylon, polyester, rayon, etc.) with a coat rubber, and has an absolute value of 80 [deg] or more and 95. [Deg] The following carcass angle (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 carcass division structure (not shown). 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.

  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. 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. The cap tread 151 having such a volume resistivity is produced by using a low exothermic compound with a small amount of carbon and increasing the silica content for reinforcement. 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 under tread 152 is a member laminated on the inner side in the tire radial direction of the cap tread 151, and preferably has a volume resistivity lower than that of the cap tread 151.

  The tan δ value of 60 [° C.] is measured using a viscoelastic spectrometer under conditions of a temperature of 60 [° C.], a shear strain of 10 [%], 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. In general, if the volume resistivity is in the range of less than 1 × 10 ^ 8 [Ω · cm], it can be said that the member has conductivity capable of suppressing electrostatic charging.

  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 1 × 10 ^ 7 [Ω · cm] or less.

  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 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 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 volume resistivity of the inner liner 18 is preferably in the range of 1 × 10 ^ 8 [Ω · cm] or more, and 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.

  2-6 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 of 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. 4 shows a plan view of the single carcass layer 13 at the time of components, and FIG. 5 shows a cross-sectional view of the carcass layer 13 shown in FIG. FIG. 6 shows a radial cross-sectional view of the weft of the carcass layer 13 shown in FIG. In FIG. 6, black circles indicate conductive fibers, and white circles indicate non-conductive fibers.

  The pneumatic tire 1 has an earth tread 51 and a carcass layer 13 made of conductive weft 132 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 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.

  As shown in FIGS. 4 and 5, the carcass layer 13 includes a carcass ply including a plurality of carcass cords 131, one or a plurality of wefts 132, and a coat rubber 133. The carcass layer 13 may be composed of a single-layer carcass ply (see FIG. 2) or may be composed of a plurality of stacked carcass plies (not shown).

  The carcass cord 131 is a member constituting the main body of the carcass layer 13. Since the carcass cord 131 is made of an organic fiber material (for example, aramid, nylon, polyester, rayon, etc.) as described above, it generally has a volume resistivity of 1 × 10 ^ 8 [Ω · cm] or more. When the carcass cord 131 is made of such an organic fiber material, the function of the carcass layer 13 as a tire skeleton is appropriately ensured. Further, as shown in FIG. 4, a plurality of carcass cords 131 are arranged in a line and parallel to each other with the longitudinal direction aligned.

  The weft 132 is a member that maintains the arrangement of the plurality of carcass cords 131 described above. The weft 132 is a conductive linear body formed by linearly molding a conductive material (for example, metal, carbon, etc.) having a volume resistivity of less than 1 × 10 ^ 8 [Ω / cm]. It has a volume resistivity of less than × 10 ^ 8 [Ω · cm]. For example, (a) metal cord, (b) spun yarn made of metal fiber or carbon fiber, (c) blended yarn of metal fiber or carbon fiber and organic fiber (for example, polyethylene terephthalate, nylon, cotton) is adopted. Can be done. In particular, the weft 132 is preferably a blended yarn of stainless steel fibers and polyester fibers (see FIG. 6).

  Moreover, it is preferable that the total fineness of the weft 132 is 150 [dtex] or more and 600 [dtex] or less. By setting the lower limit of the total fineness to the above range, disconnection of the weft 132 during tire manufacture is suppressed. Further, by setting the upper limit of the total fineness in the above range, disconnection of the weft 132 during tire rolling is suppressed. The weft 132 is preferably a single wire, but may be a twisted wire.

  The total fineness is measured in accordance with JIS L1017 Chemical Fiber Tire Cord Test Method 8.3 Positive Fineness.

  Further, as shown in FIGS. 4 and 5, the weft 132 is woven so as to intersect with a plurality of arranged carcass cords 131. At this time, the weft 132 is continuously arranged in the longitudinal direction of the cord so as to be conductive. In addition, in the state where the carcass layer 13 is incorporated in the tire, the weft 132 needs to be continuously arranged so as to be conductive at least from the bead portion to the belt layer 14. Thereby, a conductive path from the weft 132 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.

  For example, in the configuration of FIGS. 4 and 5, a shuttle loom is used, and the weft 132 is woven in a hook shape with the carcass cord 131 as a warp. For this reason, one weft 132 extends continuously in the longitudinal direction of the carcass cord 131 while reciprocating in the arrangement direction of the carcass cord 131 to form one conduction path.

  In the state where the carcass layer 13 is incorporated in the tire, the longitudinal direction of the carcass cord 131 is arranged at an angle of 80 [deg] or more and 95 [deg] or less in absolute value with respect to the tire circumferential direction. For this reason, one weft 132 extends continuously in the tire radial direction while reciprocating in the tire circumferential direction to form one conduction path in the tire radial direction.

  Not limited to the above, the weft 132 may be woven into the carcass cord 131 by using a slewer loom on the condition that the weft 132 is continuous in the longitudinal direction of the carcass cord 131. Further, the arrangement interval of the weft 132 in the longitudinal direction of the carcass cord 131 is not particularly limited and may be coarse.

  The coat rubber 133 is a rubber member that covers the carcass cord 131 and the weft 132. The coat rubber 133 is an unvulcanized rubber at the time of molding a clean tire, and has a function of improving the adhesion between the carcass layer 13 and the adjacent member. Specifically, an unvulcanized coat rubber containing natural rubber, synthetic rubber and carbon black is applied to the entire woven carcass cord 131 and weft 132 and calendered, so that the carcass layer 13 as a part is formed. Is formed.

  The tan δ value at 60 [° C.] of the coat rubber 133 is preferably 0.20 or less. The volume resistivity of the coat rubber 133 is preferably 1 × 10 ^ 8 [Ω · cm] or more. Coated rubber having a high volume resistivity is produced by using a low exothermic compound with a low carbon content 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.

  In the above configuration, static electricity generated in the vehicle is discharged from the rim R through the rim cushion rubber 17, the weft 132 of the carcass layer 13 and the belt layer 14 to the road surface from the earth tread 51 (see FIGS. 1 and 2). . Thereby, charging of the vehicle due to static electricity is suppressed.

  The rim cushion rubber 17, the coat rubber 133 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.

[Modification]
In the configuration of FIG. 1, the carcass layer 13 is arranged so as to be bridged between the left and right bead cores 11, 11. Further, as shown in FIG. 4, the conductive weft 132 is uniformly woven into the entire carcass layer 13. For this reason, the weft 132 extends continuously across the tire across the bead portions on the left and right sides of the tire. For this reason, a conductive path is formed from the left and right bead portions to the earth tread 51 via the left and right sidewall portions. Thereby, the conductive efficiency is effectively enhanced.

  However, the present invention is not limited to this, and the carcass layer 13 may include a pair of left and right carcass plies arranged separately in the tire width direction (not shown). In such a configuration, the conductive weft 132 does not need to be disposed on each of the left and right carcass plies, and may be disposed on at least one of the carcass plies.

  Further, the conductive weft 132 may be continuously arranged so as to be conductive at least from the bead portion to the belt layer 14. Thereby, a conductive path from the weft 132 to the belt layer 14 is secured.

  For example, as described above, in a configuration including a pair of left and right carcass plies in which the carcass layer 13 is disposed separately in the tire width direction, the end portion of the carcass ply having the conductive weft 132 on the outer side in the tire radial direction is What is necessary is just to extend to the position which wraps with respect to the belt layer 14 in a tire width direction. Further, for example, the conductive weft 132 is disposed only in a part of the region including the range from the bead portion to the belt layer 14, and a non-conductive non-conductive weft is disposed in the other region. (Not shown).

  At this time, the wrap width La (not shown) between the belt layer 14 and the weft 132 is preferably in the range of 3 [mm] ≦ La. The upper limit of the wrap width La is not particularly limited.

  The lap width La is a cross-sectional view in the tire meridian direction. A perpendicular line is drawn from the end of the belt layer 14 on the outer side in the tire width direction of the widest belt ply 141 to the arrangement region of the weft yarn 132, and the weft thread from the foot of the perpendicular line Measured as the way to the end of 132 placement areas.

  1, the carcass layer 13 has a single-layer structure composed of a single carcass ply (see FIG. 2), and the single carcass ply is arranged over the entire circumference in the tire circumferential direction. (Not shown). Further, as shown in FIG. 4, the conductive weft 132 is uniformly woven into the entire carcass layer 13. For this reason, the conductive weft 132 extends continuously over the entire region in the tire circumferential direction.

  However, the present invention is not limited to this, and the conductive weft 132 may be disposed only in a partial region in the tire circumferential direction. For example, the conductive weft 132 may be arranged only in a partial region in the tire circumferential direction, and a non-conductive non-conductive weft may be arranged in the other region.

  Further, in the configuration in which the carcass layer 13 is formed by laminating a plurality of carcass plies, it is sufficient that at least one carcass ply has the conductive weft 132.

  In the configuration of FIG. 1, as shown in FIG. 2, the left and right end portions of the carcass layer 13 are wound up outward in the tire width direction to wrap the bead core 11. Further, as shown in FIG. 4, the conductive weft 132 is uniformly woven into the entire carcass layer 13. For this reason, the conductive weft 132 is disposed so as to wrap the bead core 11. Such a configuration is preferable because the conductivity from the rim cushion rubber 17 to the weft 132 is improved.

  However, the present invention is not limited to this, and the carcass layer 13 may be terminated on the side of the bead core 11 or on the radially inner side of the bead core 11 without wrapping the bead core 11 (so-called turn-down structure). Even with this configuration, the conductivity from the rim cushion rubber 17 to the weft 132 is ensured.

  Further, in the configuration of FIG. 1, as shown in FIG. 3, the earth tread 51 is exposed on the tread surface of the tread rubber 15 in a cross-sectional view in the tire meridian direction, and passes through the cap tread 151 and the under tread 152. The layer 14 (the belt cover 143 in the outermost layer) is in conductive contact. 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.

  However, the invention is not limited thereto, and the earth tread 51 may penetrate only the cap tread 151 and contact the under tread 152 (not shown). Even in such a configuration, by setting the resistivity of the undertread 152 to be low, the charge suppressing action can be enhanced.

  Further, the earth tread 51 may have a shape widened from the tread rubber 15 tread surface toward the belt layer 14, and the contact surface with the belt layer 14 may be increased (not shown). 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.

[effect]
As described above, the pneumatic tire 1 includes a pair of bead cores 11, a carcass layer 13 that spans the bead core 11, a belt layer 14 that is disposed on the outer side in the tire radial direction of the carcass layer 13, and a belt The tread rubber 15 disposed on the outer side in the tire radial direction of the layer 14, the pair of sidewall rubbers 16 and 16 disposed on the outer side in the tire width direction of the carcass layer 13, and the inner peripheral surface of the carcass layer 13. And an inner liner 18 (see FIG. 1). The carcass layer 13 includes a plurality of carcass cords 131 arranged in parallel to each other and at least one weft 132 woven so as to intersect the carcass cords 131 (see FIGS. 4 and 5). Further, the weft 132 has a volume resistivity of less than 1 × 10 ^ 8 [Ω · cm] and continuously extends at least from the bead portion to the belt layer 14 so as to be conductive.

  In such a configuration, the weft 132 of the carcass layer 13 secures a conductive path from the bead portion to the belt layer 14, so that there is an advantage that the antistatic performance of the tire is effectively improved.

  In the pneumatic tire 1, the weft 132 is a conductive linear body formed by linearly forming a conductive material having a volume resistivity of less than 1 × 10 ^ 8 [Ω / cm]. As a result, there is an advantage that a decrease in the conductivity of the weft 132 in the tire manufacturing process or in the tire use state is suppressed, and the charging suppression performance of the tire is appropriately ensured. For example, in a configuration in which a non-conductive weft, which is a general-purpose product, is coated with a conductive material, the coating is easily peeled off due to heat and strain in the tire manufacturing process and 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, so that the inner liner 18 is inside the tire at the time of tire vulcanization molding. The weft 132 becomes hot. For this reason, in the structure formed by coating a non-conductive weft with a conductive material, the coating is easy to peel off, which is not preferable.

  In the pneumatic tire 1, the total fineness of the weft yarn is in the range of 150 [dtex] to 600 [dtex]. Thereby, there exists an advantage by which the total fineness of a weft is optimized. That is, when the total fineness is 150 [dtex] or more, the breakage of the wefts during the manufacture of the tire is suppressed. Moreover, when the total fineness is 600 [dtex] or less, an increase in rolling resistance due to an increase in tire weight is suppressed. Further, workability when the carcass cord 131 and the weft 132 are covered with the coat rubber 133 is improved.

  In the pneumatic tire 1, the weft 132 is woven into the carcass cord 131 by a shuttle weave (see FIGS. 4 and 5). In such a configuration, since the weft 132 extends continuously in the longitudinal direction of the carcass cord 131, when the carcass layer 13 is arranged with the longitudinal direction of the carcass cord 131 oriented in the tire radial direction, the weft 132 is the tire diameter. Can extend continuously in the direction. Thereby, there exists an advantage by which the electrically conductive path | route from a bead part to the belt layer 14 is ensured appropriately.

  In the pneumatic tire 1, the volume resistivity of the coat rubber 133 of the carcass layer 13 is 1 × 10 ^ 8 [Ω · cm] or more. In such a configuration, since the amount of carbon blended in the coat rubber 133 can be reduced, there is an advantage that heat generation of the coat rubber 133 during tire rolling can be suppressed and the rolling resistance of the tire can be reduced.

  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). In addition, 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 volume 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.

  Moreover, in this pneumatic tire 1, the volume resistivity of the sidewall rubber 16 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 sidewall rubber 16 to achieve the above configuration, there is an advantage that the rolling resistance of the tire is reduced.

  FIG. 7 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 relating to the low rolling resistance performance, an indoor drum type tire rolling resistance tester having a drum diameter of 1707 [mm] is used. Further, the test tire is assembled to an applicable rim stipulated by JATMA, and a normal internal pressure and a maximum load stipulated by JATMA are applied to the test tire. And the rolling resistance of a tire is measured based on the measuring method of JATMA Y / B 2012 version. The evaluation is performed by index evaluation using the conventional example as a standard (100), and the larger the value, the smaller the rolling resistance.

  (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 120 minutes at a speed of 81 [km / h], giving 80% of the maximum load. The evaluation is performed by index evaluation based on a new tire of the conventional example as a reference (100), and the larger the value, the smaller the electrical resistance of the tire, which is preferable.

  The test tires of Examples 1 to 9 have the configuration shown in FIG. 1, and have an earth tread 51 and a carcass layer 13 made of conductive weft 132 as the charge suppression structure 5. Further, the earth tread 51 has a volume resistivity of 4.0 × 10 ^ 6 [Ω / cm]. The weft 132 of the carcass layer 13 is made of a blended yarn of stainless steel and non-conductive fibers made of cotton or polyethylene terephthalate, and has a volume resistivity of less than 1 × 10 ^ 8 [Ω / cm] as a whole. . The carcass cord 131 is made of an organic fiber and has a volume resistivity of 1 × 10 ^ 13 [Ω · cm].

  In the conventional test tire, in the test tire of Example 1, the wefts of the carcass layer 13 are cotton spun yarns. In the test tire of the comparative example, the weft of the carcass layer 13 in the test tire of Example 1 is a nylon thread on which a conductive coating is formed.

  As the test results show, it can be seen that in the test tires of Examples 1 to 6, the rolling resistance performance and the charge suppression performance of the tire are improved.

  1: Pneumatic tire, 5: Antistatic structure, 51: Earth red, 11: Bead core, 12: Bead filler, 13: Carcass layer, 131: Carcass cord, 132: Weft, 133: Coat rubber, 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

Claims (12)

A pair of bead cores, a carcass layer spanning the bead core, 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 the carcass layer A pneumatic tire comprising a pair of sidewall rubbers respectively disposed on the outer side in the tire width direction, and an inner liner disposed on an inner peripheral surface of the carcass layer,
The carcass layer has a plurality of carcass cords made of an organic fiber material and arranged in parallel to each other, and at least one weft woven across the carcass cords, and
The pneumatic tire is characterized in that the weft has a volume resistivity of less than 1 × 10 ^ 8 [Ω · cm] and continuously extends at least from the bead portion to the belt layer so as to be conductive. The pneumatic tire according to claim 1, wherein the weft is a conductive linear body formed by linearly forming a conductive material having a volume resistivity of less than 1 × 10 ^ 8 [Ω · cm] .   The pneumatic tire according to claim 1 or 2, wherein a total fineness of the weft yarn is in a range of 150 [dtex] to 600 [dtex].   The pneumatic tire according to any one of claims 1 to 3, wherein the weft is woven into the carcass cord by a shuttle weave.   The pneumatic tire according to any one of claims 1 to 4, wherein the volume resistivity of the coat rubber of the carcass layer is 1 x 10 ^ 8 [Ω · cm] or more.   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
The pneumatic tire according to claim 1, wherein a volume resistivity of the cap tread is in a range of 1 × 10 ^ 8 [Ω · cm] or more. 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 earth tread having a volume resistivity of less than 1 × 10 ^ 8 [Ω · cm] and at least penetrating through the cap tread and exposed to a tire contact surface is provided. Pneumatic tire.   The pneumatic tire according to any one of claims 1 to 8, wherein a volume resistivity of the sidewall rubber is in a range of 1 x 10 ^ 8 [Ω · cm] or more.   The pneumatic tire according to claim 1, wherein the weft is a spun yarn made of metal fiber or carbon fiber.   The pneumatic tire according to claim 1, wherein the weft is a mixed fiber of metal fiber or carbon fiber and organic fiber.   The said weft is arrange | positioned only in the one part area | region containing the range from a bead part to the said belt layer, and a nonelectroconductive weft is arrange | positioned in the other area | region to any one of Claims 1-11. The described pneumatic tire.

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