JP2015123905A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving steering stability performance of the tire in a configuration including bead fillers made of a thermoplastic resin or a thermoplastic elastomer composition.SOLUTION: A pneumatic tire 1 comprises: a pair of bead cores 51 and 51; a pair of bead fillers 52 and 52 which are arranged radially on the outsides of the pair of bead cores 51 and 51, respectively; and carcass layers 6 (61 to 63) stretched between the pair of bead cores 51 and 51. In addition, the bead fillers 52 comprise: bases 521 constituted of a thermoplastic elastomer composition obtained by blending a thermoplastic resin or a thermoplastic resin component with an elastomer component, and having a Young's modulus of 30[MPa] to 600[MPa]; and cords 522 which are buried in the bases 521, and continuously extend by one or more rounds in a tire circumferential direction.

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire capable of improving the steering stability performance of the tire with a configuration including a bead filler made of a thermoplastic resin or a thermoplastic elastomer composition.

  In recent years, a bead filler composed of a thermoplastic resin or a thermoplastic elastomer composition formed by blending a thermoplastic resin component and an elastomer component has been proposed in order to ensure appropriate rigidity while reducing the weight of the tire. . As a conventional pneumatic tire having such a configuration, a technique described in Patent Document 1 is known.

Japanese Patent Laid-Open No. 9-300924

  On the other hand, in a pneumatic tire, there is a problem that should improve the steering stability performance of the tire.

  Accordingly, the present invention has been made in view of the above, and provides a pneumatic tire capable of improving the steering stability performance of a tire with a configuration including a bead filler made of a thermoplastic resin or a thermoplastic elastomer composition. For the purpose.

  In order to achieve the above object, a pneumatic tire according to the present invention includes a pair of bead cores, a pair of bead fillers disposed radially outside the pair of bead cores, and a carcass layer spanned between the pair of bead cores. The bead filler is made of a thermoplastic elastomer or a thermoplastic elastomer composition obtained by blending a thermoplastic resin component and an elastomer component, and is 30 [MPa] to 600 [MPa]. ] A base having the following Young's modulus, and a cord embedded in the base and extending continuously one or more times in the tire circumferential direction.

  In the pneumatic tire according to the present invention, the bead filler is reinforced by the cord being embedded in the base. Thereby, there exists an advantage which the steering stability performance of a tire improves.

FIG. 1 is a meridional sectional view of a pneumatic tire according to this embodiment. FIG. 2 is a partially enlarged meridional sectional view showing a carcass layer of the pneumatic tire shown in FIG. 1. FIG. 3 is a partially enlarged meridional sectional view showing a carcass layer of the pneumatic tire shown in FIG. 1. FIG. 4 is an explanatory view showing a method for manufacturing the pneumatic tire shown in FIG. 1. FIG. 5 is an explanatory view showing a method for manufacturing the pneumatic tire shown in FIG. 1. FIG. 6 is an explanatory diagram showing a method for manufacturing the pneumatic tire depicted in FIG. 1. FIG. 7 is an explanatory view showing a method for manufacturing 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 a chart showing the results of a performance test of a pneumatic tire.

  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 meridional sectional view of a pneumatic tire according to this embodiment. In the following description, the tire radial direction refers to a direction orthogonal to the rotation axis (not shown) of the pneumatic tire 1, and the tire radial direction inner side refers to the side toward the rotation axis in the tire radial direction, the tire radial direction outer side. Means the side away from the rotation axis in the tire radial direction. Further, the tire circumferential direction refers to a direction around the rotation axis as a central axis. Further, the tire width direction means a direction parallel to the rotation axis, the inner side in the tire width direction means the side toward the tire equator plane (tire equator line) CL in the tire width direction, and the outer side in the tire width direction means the tire width direction. Is the side away from the tire equatorial plane CL. The tire equatorial plane CL is a plane that is orthogonal to the rotation axis of the pneumatic tire 1 and passes through the center of the tire width of the pneumatic tire 1. The tire width is the width in the tire width direction between the portions located outside in the tire width direction, that is, the distance between the portions farthest from the tire equatorial plane CL in the tire width direction. The tire equator line is a line along the tire circumferential direction of the pneumatic tire 1 on the tire equator plane CL. In the present embodiment, the same sign “CL” as that of the tire equator plane is attached to the tire equator line.

  As shown in FIG. 1, the pneumatic tire 1 according to the present embodiment includes a tread portion 2, shoulder portions 3 on both sides thereof, and a sidewall portion 4 and a bead portion 5 that are sequentially continuous from the shoulder portions 3. Yes. The pneumatic tire 1 includes a carcass layer 6, a belt layer 7, and a belt reinforcing layer 8.

  The tread portion 2 is made of a rubber material (tread rubber), is exposed at the outermost side in the tire radial direction of the pneumatic tire 1, and the surface thereof is the contour of the pneumatic tire 1. A tread surface 21 is formed on the outer peripheral surface of the tread portion 2, that is, on the tread surface that contacts the road surface during traveling. The tread surface 21 is provided with a plurality of (four in this embodiment) main grooves 22 extending along the tire circumferential direction. The tread surface 21 is formed with a plurality of rib-like land portions 23 extending along the tire circumferential direction by the plurality of main grooves 22. Although not shown in the figure, the tread surface 21 is provided with a lug groove that intersects the main groove 22 in each land portion 23. The land portion 23 is divided into a plurality of portions in the tire circumferential direction by lug grooves. Further, the lug groove is formed to open to the outer side in the tire width direction on the outermost side in the tire width direction of the tread portion 2. Note that the lug groove may have either a form communicating with the main groove 22 or a form not communicating with the main groove 22.

  The shoulder portion 3 is a portion on both outer sides in the tire width direction of the tread portion 2. Further, the sidewall portion 4 is exposed at the outermost side in the tire width direction of the pneumatic tire 1. The bead unit 5 includes a bead core 51 and a bead filler 52. The bead core 51 is formed by winding a bead wire, which is a steel wire, in a ring shape. The bead filler 52 is a rubber material disposed in a space formed by winding up the end portion in the tire width direction of the carcass layer 6 at the position of the bead core 51.

  The carcass layer 6 has both ends in the tire width direction wound around a pair of bead cores 51 from the inner side in the tire width direction to the outer side in the tire width direction and extended outward in the tire radial direction. It constitutes the skeleton of the tire. Details of the carcass layer 6 will be described later.

  The belt layer 7 has a multilayer structure in which at least two belt plies 71 and 72 are laminated. The belt layer 7 is disposed on the outer side in the tire radial direction which is the outer periphery of the carcass layer 6 in the tread portion 2 and covers the carcass layer 6 in the tire circumferential direction. Is. In the belt plies 71 and 72, a plurality of cords (not shown) arranged in parallel at a predetermined angle (for example, 20 degrees to 30 degrees) with respect to the tire circumferential direction are covered with coat rubber. The cord is made of steel or organic fiber (polyester, rayon, nylon, etc.). Further, the overlapping belt plies 71 and 72 are arranged so that the cords intersect each other.

  The belt reinforcing layer 8 is disposed on the outer side in the tire radial direction which is the outer periphery of the belt layer 7 and covers the belt layer 7 in the tire circumferential direction. The belt reinforcing layer 8 is formed by coating a plurality of cords (not shown) arranged substantially parallel (± 5 degrees) in the tire circumferential direction and in the tire width direction with a coat rubber. The cord is made of steel or organic fiber (polyester, rayon, nylon, etc.). The belt reinforcing layer 8 shown in FIG. 1 includes a belt reinforcing layer 81 disposed so as to cover the entire belt layer 7 on the outer side in the tire radial direction of the belt layer 7, and the belt layer 7 on the outer side in the tire radial direction of the belt reinforcing layer 81. The belt reinforcing layer 82 is arranged so as to cover the whole, and the belt reinforcing layer 83 is arranged so as to cover each end in the tire width direction of the belt layer 7 outside the belt reinforcing layer 82 in the tire width direction. Has been. The configuration of the belt reinforcing layer 8 is not limited to the above, and is not clearly shown in the figure, but is configured to cover the entire belt layer 7 or to cover each end of the belt layer 7 in the tire width direction. There are only configurations arranged in the above, or a combination of these as appropriate. That is, the belt reinforcing layer 8 overlaps at least both ends of the belt layer 7 in the tire width direction. The belt reinforcing layer 8 is provided by winding a strip-shaped strip material (for example, a width of 10 [mm]) in the tire circumferential direction. The belt reinforcing layer 8 may be omitted (not shown).

[Carcass layer]
2 and 3 are partially enlarged meridional sectional views showing the carcass layer of the pneumatic tire shown in FIG. In these drawings, FIG. 2 shows an enlarged sectional view of the bead portion 5, and FIG. 3 shows an enlarged sectional view of the shoulder portion 3.

  In the pneumatic tire 1 described above, the carcass layer 6 is composed of at least two layers (three layers in FIG. 1), and is formed of thermoplastic sheets (61, 62, 63). And as for the thermoplastic sheet (61, 62, 63), the rubber layer 6a is arrange | positioned while each layer overlaps. In FIG. 2, the rubber layer 6 a is also provided outside the thermoplastic sheet 61 which is the outermost part in the rolled-up portion of the bead portion 5, except during the overlapping of the layers of the thermoplastic sheets (61, 62, 63). The form is shown.

  The thermoplastic sheet (61, 62, 63) is composed of a thermoplastic resin or a thermoplastic elastomer composition obtained by blending an elastomer component in a thermoplastic resin, and has no cord.

  As the thermoplastic resin used in the present embodiment, for example, polyamide resin [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 copolymer, 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 / PEI copolymer, polyarylate (PAR), polybutylene naphthalate (PBN), liquid crystal polyester, aromatic polyester such as polyoxyalkylene diimide diacid / polybutylene terephthalate copolymer], polynitrile series Resins [eg, polyacrylonitrile (PAN), polymethacrylonitrile, acrylonitrile / styrene copolymer (AS), methacrylonitrile / styrene copolymer, methacrylonitrile / styrene / butadiene copolymer], poly (meth) acrylate Resin (for example, polymethyl methacrylate (PMMA), polyethyl methacrylate, ethylene ethyl acrylate copolymer (EEA), ethylene acrylic acid copolymer (EAA), ethylene methyl acrylate resin (EMA)), polyvinyl Fat [for example, vinyl acetate (EVA), polyvinyl alcohol (PVA), vinyl alcohol / ethylene copolymer (EVOH), polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), vinyl chloride / vinylidene chloride copolymer, chloride Vinylidene / methyl acrylate copolymer], cellulose resin [eg, cellulose acetate, cellulose acetate butyrate], fluorine resin [eg, polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), polychlorofluoroethylene (PCTFE), tetra Fluoroethylene / ethylene copolymer (ETFE)], imide resin [for example, aromatic polyimide (PI)] and the like.

  Examples of the elastomer used in this embodiment 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], olefin rubber [eg 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), chlorine 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 elastomer (for example, styrene elastomer, olefin elastomer, polyester elastomer, Urethane elastomer, polyamide elastomer] and the like.

  As described above, in the pneumatic tire 1 of the present embodiment, at least two carcass layers 6 extend to the bead core 51 in which both end portions in the tire width direction are arranged in the bead portions 5 and the tire width of the bead core 51 is increased. In the pneumatic tire 1 wound up from the inner side in the tire width direction outer side and extended outward in the tire radial direction, the carcass layer 6 is formed of a thermoplastic sheet (61, 62, 63), and is at least thermoplastic. The rubber layer 6a is disposed between the layers of the sheets (61, 62, 63).

  According to this pneumatic tire 1, the carcass layer 6 is formed of a thermoplastic sheet (61, 62, 63), and the rubber layer 6 a is disposed at least between each layer, thereby being applied to a general pneumatic tire. Such a carcass cord arranged in the tire width direction has a function to become a tire skeleton, similar to the carcass layer 6 covered with the coat rubber. This thermoplastic sheet (61, 62, 63) is lighter than the carcass cord. As a result, the tire weight can be further reduced.

  Moreover, according to the pneumatic tire 1, the carcass layer 6 is formed of the thermoplastic sheet (61, 62, 63), so that air leakage required for an inner liner applied to the inside of a general pneumatic tire is obtained. Has a suppression function. As a result, the inner liner can be omitted and the tire weight can be further reduced.

  Furthermore, according to this pneumatic tire 1, since the carcass layer 6 is formed of the thermoplastic sheet (61, 62, 63), in the carcass layer 6, a calendar process (rubber sheeting (sheet processing), woven fabric) The step of performing a rubber coating (topping process) operation or the like can be omitted, so that the tire manufacturing process can be simplified.

  The average thickness of the rubber layer 6a is preferably 0.05 [mm] or more and 0.5 [mm] or less, and more preferably 0.10 [mm] or more and 0.30 [mm] or less. preferable. The rubber layer 6a can be easily molded by the above lower limit, and an increase in tire weight can be suppressed by the above upper limit.

  In the pneumatic tire 1 of the present embodiment, the thermoplastic sheet (61, 62, 63) forming the carcass layer 6 has a single layer average thickness of 0.03 [mm] or more and 1.00 [mm] or less. And the air permeability coefficient is 3 × 10 ^ -12 [cc · cm / cm ^ 2 · sec · cmHg] or more and 500 × 10 ^ -12 [cc · cm / cm ^ 2 · sec · cmHg] or less. It is preferable.

Here, the average thickness is determined by cutting the tire to be measured in the tire circumferential direction with a width of 20 [mm] to 30 [mm] in the tire circumferential direction, and dividing the length in the tire width direction into at least eight equal parts. The thickness of each of the thermoplastic sheets (61, 62, 63) constituting the material is measured and averaged for a single layer. The air permeability coefficient is JIS K7126 “Plastic film and sheet gas permeability test method (A)”, the test gas is air (N ₂ : O ₂ = 8: 2), and the test temperature is 30 ° C. ].

  According to this pneumatic tire 1, the thermoplastic sheet (61, 62, 63) has a remarkable function as a tire skeleton by defining the thickness, and the inner liner function by defining the air permeability coefficient. Therefore, the effect of reducing the tire weight can be remarkably obtained. The average thickness of the single layer of the thermoplastic sheets (61, 62, 63) is 0.05 [mm] or more and 0.002 mm in order to obtain the effect of reducing the tire weight while also serving as the inner liner. More preferably, the average thickness of the single layer of the thermoplastic sheet (61, 62, 63) is more preferably 6 [mm] or less, in order to obtain a more remarkable effect of reducing the tire weight while also serving as an inner liner. More preferably, the thickness is 0.08 [mm] or more and 0.5 [mm] or less.

  In the pneumatic tire 1 of the present embodiment, the rubber layer 6a has a peel strength of 50 [N / 25 mm] or more and 400 [N / 25 mm] or less from the thermoplastic sheet (61, 62, 63). preferable.

  Here, the peel strength is obtained according to JIS K6256.

  According to the pneumatic tire 1, the adhesion between the carcass layers 6 is improved by the regulation of the peel strength of the rubber layer 6a, and as a result, the durability of the tire can be improved. The upper limit of the peel strength may exceed 400 [N / 25 mm], but it tends to be in close contact with the metal drum of the supply device at the time of tire molding, resulting in a decrease in handling properties and difficulty in correction. 25 mm]. In order to obtain the effect of improving the durability remarkably, the peel strength of the rubber layer 6a is more preferably 75 [N / 25 mm] or more and 400 [N / 25 mm] or less, and the durability is further improved and the tire is molded. In order to remarkably obtain the effect of further improving the handleability at the time, it is more preferable that the peel strength of the rubber layer 6a is 100 [N / 25 mm] or more and 300 [N / 25 mm] or less.

Further, in the pneumatic tire 1 of the present embodiment, the rubber layer 6a has R ¹ , R ² , R ³ , R ⁴ and R ⁵ in the following formula (1), each having hydrogen, a hydroxyl group or a carbon atom number of 1. A rubber composition containing a condensate of formaldehyde and 8 or less alkyl groups and formaldehyde, a methylene donor, and a vulcanizing agent, the blending amount of the condensate being 100 parts by mass of the rubber component The blending amount of methylene donor is 0.5 to 80 parts by weight with respect to 100 parts by weight of the rubber component, and the blending amount of methylene donor / condensation is 0.5 to 20 parts by weight. It is preferable that the ratio of the amount of the product is 1 or more and 4 or less.

  According to this pneumatic tire 1, it becomes possible to improve the adhesiveness of the rubber layer 6a to the thermoplastic sheets (61, 62, 63). That is, the peel strength of the rubber layer 6a with respect to the thermoplastic sheet (61, 62, 63) is improved, the adhesion between the carcass layers 6 is improved, and as a result, the durability as a tire can be improved.

  Moreover, in the pneumatic tire 1 of this embodiment, it is preferable that the thermoplastic sheet (61, 62, 63) has a single layer tensile yield strength at room temperature of 1 [MPa] to 100 [MPa].

  Here, the tensile yield strength is obtained by measuring by a test method specified in JIS K7113.

  According to this pneumatic tire 1, plastic deformation when the thermoplastic sheet (61, 62, 63) is pulled is suppressed by the regulation of the tensile yield strength of the thermoplastic sheet (61, 62, 63). It becomes possible to improve pressure resistance. By improving the pressure resistance, it is possible to reduce the number of laminated thermoplastic sheets (61, 62, 63) and improve the weight reduction of the tire. The upper limit of tensile yield strength may exceed 100 [MPa], but the shape tends to become non-uniform in the expansion of the thermoplastic sheet (61, 62, 63) during inflation molding. For ease of manufacturing, the pressure was set to 100 [MPa]. The tensile yield strength of the thermoplastic sheet (61, 62, 63) is set to 2 in order to significantly reduce the number of laminated thermoplastic sheets (61, 62, 63) and to obtain the effect of facilitating production. More preferably, the pressure is set to [MPa] or more and 80 [MPa] or less.

  Moreover, in the pneumatic tire 1 of this embodiment, it is preferable that the thermoplastic sheet (61, 62, 63) has a single-layer elongation at break of 80 [%] to 500 [%] at room temperature.

  According to this pneumatic tire 1, for example, even if local distortion occurs in the tire due to a tool or the like during rim assembly work, the thermoplastic sheet (61, 62, 63) can be prevented from being broken. It is possible to use a mount (rim assembly) device. Moreover, the tire durability at the time of actual use is also improved by ensuring the breaking elongation. In addition, although the upper limit of breaking elongation may exceed 500 [%], it was prescribed | regulated as a realizable range. In addition, in order to obtain the effect which ensures the durability of a thermoplastic sheet (61, 62, 63) notably, elongation at break of a thermoplastic sheet (61, 62, 63) is 100 [%] or more and 500 [%] or less. More preferably.

  In the pneumatic tire 1 of the present embodiment, the thermoplastic sheet (61, 62, 63) has a relationship between the tensile yield strength α with respect to the tire circumferential direction and the tensile yield strength β with respect to the tire width direction. It is preferable to satisfy the range of <β / α ≦ 5.

  According to this pneumatic tire 1, by making the tensile yield strength β in the tire width direction larger than the tensile yield strength α in the tire circumferential direction, the tire circumferential direction is easily deformed and the tire width direction is deformed. It becomes difficult. As a result, since the contact shape (contact length) of the tire can be made more appropriate, it is possible to improve steering stability.

  In the thermoplastic sheet (61, 62, 63), the relationship between the tensile yield strength α with respect to the tire circumferential direction and the tensile yield strength β with respect to the tire width direction is in the range of 1 <β / α ≦ 5. There are the following methods.

  For example, the stretch ratios of the thermoplastic sheet (61, 62, 63) in the tire circumferential direction and the tire width direction of the thermoplastic sheet (61, 62, 63) are varied to vary the rigidity.

  Furthermore, in order to give anisotropy to the thermoplastic sheet (61, 62, 63), a notch, a through hole, a non-penetrating recess, etc. are formed at any location of the thermoplastic sheet (61, 62, 63). It may be done (not shown).

  In the configuration of FIG. 1, as shown in FIGS. 2 and 3, the laminate 60 has three carcass layers 61 to 63 made of a thermoplastic sheet. The rubber layer 6a is sandwiched between the adjacent carcass layers 61, 62; 62, 63. Thereby, the rubber layer 6a functions as a protective material, and mutual contact between the adjacent carcass layers 61, 62; 62, 63 is prevented.

  2 and 3, the rubber layer 6 a is disposed on the outer peripheral surface of the winding portion of the laminate 60. Thereby, the rubber layer 6a functions as a protective material, and the carcass layer 61 in the outermost layer of the turn-up portion and peripheral members (for example, the side wall rubber 41, the rim cushion rubber 53, the belt ply 71 of the belt layer 7, 72, belt reinforcement layers 81-83, etc.).

  2 and 3, the rubber layer 6a is disposed on the inner peripheral surface of the winding portion of the laminate 60. As a result, the rubber layer 6a functions as a protective material to prevent contact between the carcass layer 63 in the innermost layer of the rewinding portion and peripheral members (for example, the bead core 51, the bead filler 52, etc.), and rewinding. This prevents self-contact between the main body portion of the carcass layer 63 in the innermost layer and the winding portion.

  2 and 3, the rubber layer 6a is disposed on the entire inner surface of the laminate 60 on the tire lumen side. However, the rubber layer 6a is not limited to the inner surface on the tire lumen side. There may be a region where the layer 6a is not disposed. This is because the rubber layer 6a is intended to prevent mutual contact between the carcass layers 61. Furthermore, the carcass layers 61 to 63 themselves function as an inner liner by being made of a thermoplastic sheet having low gas permeability.

  Further, in the configuration of FIG. 1, as shown in FIG. 3, the end portion on the outer side in the tire radial direction in the rolled-up portions of all the carcass layers 61 to 63 is located on the inner side in the tire width direction from the maximum width position B1 of the belt layer 7. Has been placed. Therefore, the end portion of the carcass layer 61 is disposed between the main body portion of the carcass layer 6 and the belt layer 7. Thereby, the carcass layers 61 to 63 are stably held.

  The maximum width position B1 of the belt layer 7 refers to the position of the outer end in the tire width direction of the widest belt ply 71 among the plurality of belt plies 71, 72.

  However, the present invention is not limited to this, and it is only necessary that the end of the rolled-up portion of at least one carcass layer 6 is disposed on the inner side in the tire width direction than the maximum width position B1 of the belt layer 7. For example, part of the carcass layer 6 that is wound up may be terminated at the sidewall 4 or the bead 5 (not shown). Even in such a configuration, the carcass layer 6 is properly held.

  In the above configuration, the distance CW between the ends C1 and C1 that are the innermost in the tire width direction among the ends of the left and right winding portions of the carcass layer 6 and the maximum width BW of the belt layer 7 are 0.10. It is preferable to have a relationship of ≦ CW / BW ≦ 0.95 (see FIG. 1). Further, it is more preferable that the ratio CW / BW has a relationship of 0.15 ≦ CW / BW ≦ 0.95. Thereby, the lap width between the carcass layer 6 and the belt layer 7 is appropriately secured, and the pressure resistance and durability of the tire are appropriately secured.

  The distance CW is measured as the distance in the tire width direction of the ends C1 and C1 of the left and right winding parts of the carcass layer 6 when the tire is mounted on the specified rim to apply the specified internal pressure and is in an unloaded state. .

  The maximum width BW of the belt layer 7 is the tire width direction of the left and right maximum width positions B1 and B1 of the widest belt ply 71 when a tire is mounted on a specified rim to apply a specified internal pressure and is in an unloaded state. Measured as a distance.

  Further, in the configuration of FIG. 3, end portions of the plurality of stacked carcass layers 61 to 63 are arranged so as to be shifted from each other. Thereby, compared with the structure (illustration omitted) which has the edge part of the several carcass layers 61-63 in the same position, the air pool in the edge part position of the carcass layers 61-63 at the time of green tire shaping | molding can be reduced.

[Bead filler]
In recent years, a bead filler composed of a thermoplastic resin or a thermoplastic elastomer composition formed by blending a thermoplastic resin component and an elastomer component has been proposed in order to ensure appropriate rigidity while reducing the weight of the tire. .

  On the other hand, in a pneumatic tire, there is a problem that should improve the steering stability performance of the tire.

  In particular, when the bead filler is composed of a thermoplastic resin or a thermoplastic elastomer composition, the physical property of the bead filler is likely to change due to heat generation under high load conditions (low pressure, high load, high speed, etc.). There is a problem to suppress the temperature dependence of physical properties.

  Therefore, in the pneumatic tire 1, the following configuration is adopted in order to improve the steering stability performance of the tire.

  As shown in FIG. 2, in the pneumatic tire 1, the bead filler 52 includes a base 521 and a cord 522.

  The base 521 is made of a thermoplastic elastomer or a thermoplastic elastomer composition formed by blending a thermoplastic resin component and an elastomer component. Thereby, compared with the structure which a bead filler consists of rubber | gum, the rigidity of the bead filler 52 increases and, thereby, the volume of the bead filler 52 can be reduced.

  The Young's modulus of the base 521 is preferably 30 [MPa] or more and 600 [MPa] or less, more preferably 50 [MPa] or more and 500 [MPa] or less, and 60 [MPa] or more and 200 [MPa]. It is further preferable that Thereby, the durability of the bead filler 52 is ensured, and the riding comfort of the tire is ensured.

  The definition of a thermoplastic resin or a thermoplastic elastomer composition is synonymous with the thermoplastic resin or thermoplastic elastomer composition used for the carcass layers 61 to 63 described above.

  The Young's modulus is measured by a test method specified in JIS K6251.

  The cord 522 is embedded in the base 521 and extends continuously one or more times in the tire circumferential direction. For example, a strip material in which the cord 522 is embedded in a member that becomes the base 521 is used, and the strip material is continuously wound around the outer periphery of the bead core 51. In addition, one or a plurality of cords 522 are continuously wound around the tire circumferential direction.

  The cord 522 is preferably a composite of organic fibers. For example, the cord 522 is preferably nylon, polyester, aramid, polyketone, rayon, or the like. However, the present invention is not limited to this, and the cord 522 may be a steel cord.

  In the configuration in which the cord 522 is made of organic fibers, the total fineness of the cord 522 is preferably in the range of 2000 [dtex] to 8000 [dtex]. The outer diameter of the cord 522 is preferably in the range of 0.40 [mm] to 1.20 [mm].

  Further, the softening point of the cord 522 is preferably 190 [° C.] or higher. Specifically, the softening point of the cord 522 is preferably higher than the softening point of the base 521.

  The softening point is measured according to the chemical fiber filament yarn test method of JIS L1013.

  Further, the volume ratio of the cord 522 in the bead filler 52 is preferably 25 [%] or more and 60 [%] or less, more preferably 30 [%] or more and 55 [%] or less, and 40 [%]. More preferably, it is 50 [%] or less. At this time, it is preferable that the adjacent cords 522 and 522 are arranged separately from each other by interposing the base 521 between the adjacent cords 522 and 522. Thereby, durability of the bead filler 52 improves compared with the structure by which the adjacent cords 522 and 522 are arranged in contact with each other.

  The volume ratio of the cord 522 is calculated as a ratio between the volume of the cord 522 and the total volume of the bead filler 52.

  Further, the cord 522 preferably has a coding made of the same material as the base 521 or a material having adhesiveness to the base 521. Thereby, the interfacial adhesion between the cord 522 and the base 521 is ensured. Specifically, in the green tire molding process, a cord 522 that has been previously coded is wound around the bead core 51 and disposed. Such coding may be made of the same material as the base 521 as described above, or an adhesive such as resorcin formalin resin may be used.

  The residual strain of the cord 522 is preferably in the range of 1 [%] to 7 [%]. Therefore, the cord 522 is disposed on the outer periphery of the bead core 51 in a state having tension. In this way, when a predetermined residual strain is applied to the cord in advance, the cord is in an expanded state even if the tire is not deformed. As a result, the rigidity of the bead filler can be increased, and the tire in a minute deformation region Responsiveness is improved and steering stability performance is improved. Here, if it is less than 1%, almost no effect is obtained, and if it is more than 7%, there is a fear that the long-term cord durability may be lowered, so the above range is preferable. Moreover, 1% or more and 5% or less are preferable, and 2% or more and 5% or less are more preferable.

  The residual strain of the code 522 is measured based on the tire product state.

  Moreover, as shown in FIG. 1, it is preferable that the height BFH of the bead filler 52 and the tire cross-section height SH have a relationship of 0.25 ≦ BFH / SH, and a relationship of 0.30 ≦ BFH / SH. It is more preferable to have. The upper limit of the ratio BFH / SH is not particularly limited, but is preferably BFH / SH ≦ 0.60, and more preferably BFH / SH ≦ 0.50. Thereby, both riding comfort performance and low rolling resistance performance of the tire are compatible.

[Tire manufacturing method]
4-7 is explanatory drawing which shows the manufacturing method of the pneumatic tire described in FIG. These drawings schematically show the green tire molding process.

  In the manufacturing process of the pneumatic tire 1, various tire members are put on a molding machine to form a green tire.

  Specifically, a strip material 52a in which a cord 522 is embedded in a base material 521a made of a thermoplastic resin or a thermoplastic elastomer composition is used. The strip material 52a can be manufactured, for example, by extruding the base material 521a and the cord 522. Moreover, it is preferable that the strip material 52a has a rectangular shape or a polygonal shape so as not to collapse at the time of winding described later. In FIG. 4, the strip material 52a has a structure in which one cord 522 is embedded with a base material 521a. However, the present invention is not limited to this, and a belt-like body in which a plurality of arranged cords 522 are embedded with a base material 521a may be used (not shown).

  Next, the bead core 51 is attached to a forming drum (not shown), and the forming drum rotates to wind the strip material 52 a around the bead core 51. At this time, one strip member 52a may be used, or a plurality of strip members 52a may be wound up simultaneously. Then, as shown in FIG. 4, the strip material 52 a is wound around the outer periphery of the bead core 51 in a multiple manner to form the bead core 51. At this time, the strip material 52a may be wound in the radial direction while reciprocating in the width direction, or may be wound in the width direction while reciprocating in the radial direction. Moreover, in order to suppress the shape loss of the wound strip material 52a, the outer periphery of the strip material 52a may be coated with an adhesive. Such an adhesive is preferably made of the same material as the base 521 or a material having adhesiveness to the base 521.

  The average gauge of the base material 521a in the strip material 52a is appropriately set according to the volume ratio of the cord 522 in the bead filler 52.

  Next, as shown in FIG. 5, the assembly of the bead core 51 and the bead filler 52, the carcass layers 61 to 63, and the rubber member in which the sidewall rubber 41 and the rim cushion rubber 53 are integrated are arranged on the molding drum. And are positioned relative to each other.

  At this time, as shown in FIG. 6, the carcass layers 61 to 63 and the rubber layers 6 a are alternately laminated in advance to form a laminate 60. The thermoplastic sheet constituting the carcass layers 61 to 63 may be a belt-like member or a seamless cylindrical member (not shown) at the time of green tire molding.

  Next, as shown in FIG. 7, a turn-up bladder (not shown) is used, and the carcass layers 61 to 63, the sidewall rubber 41, and the rim cushion rubber 53 wrap around the assembly of the bead core 51 and the bead filler 52. So that it is wound up outward in the width direction. Next, the above-mentioned member is pressure-bonded by a turn-up bladder to form an annular member having a uniform cross section in the circumferential direction. Next, belt plies 71 and 72, belt reinforcing layers 81 to 83 (see FIG. 3), tread rubber, and the like constituting the belt layer 7 are disposed on the outer periphery of the annular member, and a green tire is molded.

  Next, this green tire is filled in a tire vulcanization mold (not shown). And this vulcanization mold is heated and vulcanization of a green tire is performed. Thereafter, the vulcanized tire is pulled out from the tire vulcanization mold and taken out.

[Modification]
8 and 9 are explanatory views showing a modification of the pneumatic tire shown in FIG. In these drawings, FIG. 8 shows a twisted cord formed by twisting three cords 522, and FIG. 9 shows a cross-sectional view of the twisted cord shown in FIG.

  In the configuration of FIG. 1, as shown in FIGS. 2 and 4, a single cord 522 is continuously wound around the outer periphery of the bead core 51.

  However, the present invention is not limited to this, and a twisted cord formed by twisting a plurality of cords 522 may be used as shown in FIGS. Such a twisted cord is preferable in that the rigidity of the bead filler 52 is increased because the compression rigidity in the axial direction is increased.

  In such a twisted cord, it is preferable that the filler is filled in the hollow portion X of the twisted cord. Thereby, since the hollow part X of a twisted cord is filled, the rigidity of the bead filler 52 increases. The filler is preferably made of the same material as the base 521 or a material having adhesiveness to the base 521.

  In the configuration of FIG. 1, as shown in FIG. 2, the carcass layers 61 to 63 are formed of a thermoplastic elastomer composition or a thermoplastic elastomer composition obtained by blending a thermoplastic resin component and an elastomer component. In addition, the carcass layers 61 to 63 and the rubber layers 6 a are alternately stacked to form a stacked body 60. In such a configuration, the carcass layers 61 to 63 are preferably made of a thermoplastic resin or a thermoplastic elastomer composition, so that the tire can be reduced in weight.

  However, the present invention is not limited to this, and the carcass layer 6 is rolled by coating a plurality of carcass cords with a general structure, for example, steel or organic fiber materials (for example, aramid, nylon, polyester, rayon, etc.) with a coat rubber. You may have the structure which consists of (illustration omitted).

[effect]
As described above, the pneumatic tire 1 includes a pair of bead cores 51, 51, a pair of bead cores 51, 51, a pair of bead fillers 52, 52 respectively disposed, and a pair of bead cores 51, The carcass layer 6 (61-63) spanning 51 is provided (refer FIG. 1). The bead filler 52 is composed of a thermoplastic resin or a thermoplastic elastomer composition obtained by blending a thermoplastic resin component and an elastomer component, and has a Young's modulus of 30 [MPa] to 600 [MPa]. 521 and a cord 522 that is embedded in the base 521 and extends continuously one or more times in the tire circumferential direction (see FIG. 2).

  In such a configuration, (1) the bead filler 52 is made of a thermoplastic resin or a thermoplastic elastomer composition, so that the rigidity of the bead filler 52 is increased as compared with a configuration in which the bead filler is made of rubber. The volume of the bead filler 52 can be reduced, and there is an advantage that the tire can be reduced in weight. Further, since the rigidity is increased, there is an advantage that the steering stability performance of the tire is improved.

  Further, (2) the bead filler 52 is reinforced by the cord 522 being embedded in the base 521. Thereby, there exists an advantage which the steering stability performance of a tire improves. In particular, a bead filler made of a thermoplastic resin or a thermoplastic elastomer composition has a particular problem that the physical properties are greatly reduced by heat under high load conditions (low pressure, high load, high speed, etc.). The problem of temperature dependency suppression is a problem. In this respect, in the above configuration, since the cord 522 reinforces the bead filler 52, the steering stability performance of the tire is appropriately ensured under a high load condition.

  Further, (3) since the cord 522 continuously extends in the tire circumferential direction for one or more rounds, there is an advantage that the rigidity of the bead filler 52 in the tire circumferential direction can be efficiently reinforced.

  Further, in the pneumatic tire 1, the cord 522 is an organic fiber composite. Thereby, there exists an advantage which can reduce a tire weight compared with the structure which has a steel cord whose specific gravity is heavier than an organic fiber.

  Moreover, in this pneumatic tire 1, the softening point of the cord 522 is 190 [° C.] or higher. Thereby, there exists an advantage which can suppress the fall of the physical property of the bead filler 52 resulting from the heat | fever under high load conditions more effectively.

  In the pneumatic tire 1, the volume ratio of the cord 522 in the bead filler 52 is 25 [%] or more and 60 [%] or less. Thereby, there is an advantage that the volume ratio of the cord 522 is optimized. That is, when the volume ratio of the cord 522 is 25 [%] or more, the reinforcing action of the bead filler 52 by the cord 522 is appropriately secured. Moreover, when the volume ratio of the cord 522 is 60% or less, the contact of the adjacent cords 522 and 522 is suppressed, and the durability of the bead filler 52 is improved.

  Further, in the pneumatic tire 1, the cord 522 has a coding made of the same material as the base 521 or a material having adhesiveness to the base 521. Thereby, there exists an advantage by which the adhesiveness in the interface of the code | cord | chord 522 and the base 521 is ensured appropriately.

  In the pneumatic tire 1, the residual strain of the cord 522 is 1 [%] or more and 7 [%] or less. Thereby, there is an advantage that the residual distortion of the cord 522 is optimized. That is, when the residual strain of the cord 522 is 1 [%] or more, the reinforcing action of the bead filler 52 by the cord 522 is appropriately ensured. Further, since the residual strain of the cord 522 is 7% or less, long-term cord durability can be ensured.

  Moreover, in this pneumatic tire 1, the bead filler 52 has a twisted cord formed by twisting a plurality of cords 522 (see FIGS. 8 and 9). Such a twisted cord has higher rigidity in the compression direction than the single cord 522. Thereby, there exists an advantage which the reinforcement effect | action of the bead filler 52 by the cord 522 improves effectively.

  Moreover, in this pneumatic tire 1, the bead filler 52 has the filler with which the hollow part X (refer FIG. 9) of said twisted cord is filled. Thereby, the rigidity of the twisted cord in the compression direction is increased, and there is an advantage that the reinforcing action of the bead filler 52 by the cord 522 is effectively improved.

  In the pneumatic tire 1, the height BFH of the bead filler 52 and the tire cross-section height SH have a relationship of 0.25 ≦ BFH / SH (see FIG. 1). Accordingly, there is an advantage that the height BFH of the bead filler 52 is appropriately ensured and the steering stability performance of the tire is ensured.

  In the pneumatic tire 1, the carcass layer 6 (61 to 63) is made of a thermoplastic elastomer or a thermoplastic elastomer composition obtained by blending a thermoplastic resin component and an elastomer component (see FIG. 2). Thereby, since the function of an inner liner can be provided to the carcass layer 6 (61 to 63), there is an advantage that the tire is reduced in weight.

  Further, the pneumatic tire 1 includes a rubber layer 6a interposed between the carcass layer 63 and the bead filler 52, and the peel strength between the carcass layer 63 and the rubber layer 6a is 50 [N / 25 mm] or more. Within the range of 400 [N / 25 mm] or less. Thereby, the adhesiveness between the carcass layer 6 and the bead filler 52 is improved, and there is an advantage that the durability of the tire is improved.

Moreover, in this pneumatic tire 1, the rubber layer 6a is made of a rubber composition containing a condensate of the compound represented by the formula (1) and formaldehyde, a methylene donor, and a vulcanizing agent. In addition, R ¹ , R ² , R ³ , R ⁴ and R ⁵ in the formula (1) are hydrogen, a hydroxyl group, or an alkyl group having 1 to 8 carbon atoms. Moreover, the compounding quantity of a condensate exists in the range of 0.5 to 20 mass parts with respect to 100 mass parts of rubber components. Moreover, the compounding quantity of a methylene donor exists in the range of 0.5 to 80 mass parts with respect to 100 mass parts of rubber components. Moreover, the ratio of the blending amount of the methylene donor and the blending amount of the condensate is in the range of 1 or more and 4 or less. Thereby, the adhesiveness between the carcass layer 6 and the bead filler 52 is improved, and there is an advantage that the durability of the tire is improved.

  FIG. 10 is a chart showing the results of a performance test of a pneumatic tire.

  In this performance test, evaluations on (1) load durability performance, (2) low rolling resistance performance, and (3) steering stability 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 assembled to an applicable rim specified by JATMA, and the highest air pressure and maximum load specified by JATMA are applied to the test tire.

  (1) Evaluation regarding load durability performance is performed by a low-pressure durability test using an indoor drum testing machine having a drum diameter of 1707 [mm]. Then, the travel speed is set to 80 [km / h], and the travel distance when the tire breaks is measured. Then, based on this measurement result, index evaluation using the conventional example as a reference (100) is performed. This evaluation is preferable as the numerical value increases.

  (2) In the evaluation on the low rolling resistance performance, the rolling resistance of the test tire is measured under the conditions described in ISO (International Organization for Standardization). Then, based on this measurement result, index evaluation using the conventional example as a reference (100) is performed. This evaluation is preferable as the numerical value increases.

  (3) Steering performance is evaluated by a 10-step evaluation based on the conventional example (5) after the test driver has run a predetermined circuit for 1 hour on a test vehicle equipped with test tires as pre-processing conditions. Evaluate. This evaluation is preferable as the numerical value increases.

  In the test tires of Examples 1 to 11, in the configuration of FIG. 1, a carcass layer (not shown) formed by coating an organic fiber cord with rubber, carcass layers 61 to 63 made of thermoplastic resin, and a rubber layer 6a One of the structures (see FIG. 2) formed by laminating layers. The bead filler 52 includes a base 521 and a cord 522 (see FIG. 2). Further, the material of the base 521 is a thermoplastic resin, the material of the cord 522 is an organic fiber, and is any one of nylon, rayon, and aramid. The bead filler 52 has either a structure in which a single cord 522 is wound (see FIG. 2) or a structure in which a plurality of cords 522 are twisted together (see FIGS. 8 and 9). Have.

  In the test tire of Conventional Example 1, the bead filler is made only of rubber and has no cord. In the test tire of Conventional Example 2, the bead filler is made of a thermoplastic resin, but does not have a cord. In the test tire of Conventional Example 3, the bead filler includes a base made of rubber and a cord.

  As shown in the test results, it can be seen that the test tires of Examples 1 to 11 have both load durability performance, low rolling resistance performance, and steering stability performance as compared with the test tires of Conventional Examples 1 to 3.

  1: pneumatic tire, 2: tread part, 21: tread surface, 22: main groove, 23: land part, 3: shoulder part, 4: sidewall part, 41: sidewall rubber, 5: bead part, 51: Bead core, 52: Bead filler, 52a: Strip material, 521: Base, 521a: Base material, 522: Cord, 53: Rim cushion rubber, 60: Laminate, 6, 61-63: Carcass layer, 6a: Rubber layer, 7: Belt layer, 71, 72: Belt ply, 8, 81-83: Belt reinforcing layer

Claims (12)

A pneumatic tire comprising a pair of bead cores, a pair of bead fillers arranged on the radially outer sides of the pair of bead cores, and a carcass layer spanned between the pair of bead cores,
The bead filler is composed of a thermoplastic elastomer or a thermoplastic elastomer composition formed by blending a thermoplastic resin component and an elastomer component, and has a Young's modulus of 30 [MPa] to 600 [MPa], A pneumatic tire comprising: a cord embedded in the base and extending continuously one or more times in a tire circumferential direction.   The pneumatic tire according to claim 1, wherein the cord is a composite of organic fibers.   The pneumatic tire according to claim 1 or 2, wherein a softening point of the cord is 190 ° C or higher.   The pneumatic tire according to any one of claims 1 to 3, wherein a volume ratio of the cord in the bead filler is 25 [%] or more and 60 [%] or less.   The pneumatic tire according to claim 1, wherein the cord has a cord made of the same material as the base or a material having adhesiveness to the base.   The pneumatic tire according to any one of claims 1 to 5, wherein a residual strain of the cord is 1% or more and 7% or less.   The pneumatic tire according to any one of claims 1 to 6, wherein the bead filler includes a twisted cord formed by twisting a plurality of the cords.   The pneumatic tire according to claim 7, wherein the bead filler has a filler filled in a hollow portion of the twisted cord.   The pneumatic tire according to claim 1, wherein a height BFH of the bead filler and a tire cross-sectional height SH have a relationship of 0.25 ≦ BFH / SH.   The pneumatic tire according to any one of claims 1 to 9, wherein the carcass layer is made of a thermoplastic elastomer composition obtained by blending a thermoplastic resin or a thermoplastic resin component and an elastomer component. A rubber layer interposed between the carcass layer and the bead filler; and
The pneumatic tire according to claim 10, wherein a peel strength between the carcass layer and the rubber layer is in a range of 50 [N / 25mm] to 400 [N / 25mm]. The rubber layer is composed of a rubber composition containing a condensate of the compound represented by formula (1) and formaldehyde, a methylene donor, and a vulcanizing agent,
R ¹ , R ² , R ³ , R ⁴ and R ^{5 in} formula (1) are hydrogen, a hydroxyl group, or an alkyl group having 1 to 8 carbon atoms,
The amount of the condensate is in the range of 0.5 to 20 parts by mass with respect to 100 parts by mass of the rubber component,
The amount of methylene donor is in the range of 0.5 parts by weight to 80 parts by weight with respect to 100 parts by weight of the rubber component,
The pneumatic tire according to claim 11, wherein a ratio between a blending amount of the methylene donor and a blending amount of the condensate is in a range of 1 or more and 4 or less.

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