JP5824962B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that defines a range of a carcass strength coefficient of a carcass layer.

  Conventionally, a pneumatic tire (pneumatic radial tire) described in Patent Document 1 has a tread portion that is folded from the tire inner side to the outer side around a bead core in which both end portions of a carcass layer in which reinforcing cords are arranged are arranged on left and right bead portions. At least two belt layers are arranged on the outer peripheral side of the carcass layer, and the carcass strength coefficient [N / mm · kPa] = [number of reinforcing cords driven [lines / mm]] × [reinforcing cord strength [N]] × A position where the carcass strength coefficient of the carcass layer defined by [number of carcass layers] ÷ [maximum air pressure [kPa]] is 10% of the belt width inward from the edge of the second widest belt layer. It is disclosed that 0.15 to 0.35 [N / mm · kPa] on the tread portion center side from P, and 0.5 [N / mm · kPa] or more from the position P to the bead portion. There.

JP-A-9-207512

  The inventors have found that the present invention can be put into practical use even when the carcass strength coefficient of the carcass layer is further reduced. However, although such a pneumatic tire has improved out-of-plane bending rigidity, the ride comfort during stepping is improved, but the carcass cord spacing tends to vary due to lift during molding, resulting in a decrease in uniformity. Since this tends to occur, vibration may occur when traveling on a flat road, and ride comfort may deteriorate.

  This invention is made in view of the above, Comprising: It aims at providing the pneumatic tire which can improve riding comfort performance, prescribing | regulating the range of the carcass strength coefficient of a carcass layer.

  In order to solve the above-described problems and achieve the object, the pneumatic tire of the present invention extends to a bead core in which a plurality of reinforcing cords are arranged in the tire circumferential direction and both end portions in the tire width direction are arranged in both bead portions. In a pneumatic tire comprising a carcass layer and a belt layer provided at least one outer layer in the tire radial direction of the carcass layer in the tread portion, the pneumatic tire has an inner side in the tire width direction than an end in the tire width direction of the belt layer. Thus, [Carcass strength coefficient K [N / mm · kPa]] = [Number of reinforcing cords driven [Number] in the range W2 of 5 [%] to 95 [%] of the maximum width W1 of the belt layer in the tire width direction / Mm]] × [reinforcing cord strength [N / piece]] × [number of carcass layers] ÷ [maximum air pressure [kPa]] The carcass strength coefficient K of the carcass layer defined by the equation N / mm · kPa] <K <0.35 [N / mm · kPa], and a thermoplastic elastomer or a thermoplastic elastomer composition in which an elastomer component is blended in at least a part of the range W2. A reinforcing layer made of a material is arranged.

  According to this pneumatic tire, by defining the range of the carcass strength coefficient K of the carcass layer, it is possible to improve riding comfort when riding over a step. In addition, the provision of a reinforcing layer prevents variations in the carcass cord spacing due to lift during molding and suppresses a decrease in uniformity, preventing vibrations when driving on flat roads and improving riding comfort. be able to.

  In the pneumatic tire of the present invention, the thermoplastic resin or the thermoplastic elastomer composition constituting the reinforcing layer has a storage elastic modulus E1 [MPa] and a thickness t [mm] of 6.7 t + E1-20 ≧ 0, 200t + E1−600 ≦ 0, E1> 0, and t> 0.

  When the storage elastic modulus E1 [MPa] and the thickness t [mm] of the reinforcing layer exceed the range, the weight of the reinforcing layer increases and the tire weight tends to increase. In this regard, according to the pneumatic tire of the present invention, the storage elastic modulus E1 [MPa] and the thickness t [mm] are 6.7 t + E1-20 ≧ 0, 200t + E1-600 ≦ 0, E1> 0, t> 0. Therefore, the increase in the weight of the reinforcing layer can be prevented to prevent the tire weight from increasing, and the hardness of the reinforcing layer can be prevented from increasing and the moldability of the reinforcing layer can be maintained. .

  In the pneumatic tire of the present invention, the reinforcing layer is arranged in a range in the tire width direction of 60% to 120% of the range W2.

  According to this pneumatic tire, by defining the range of the reinforcing layer in the tire width direction, the above-described effect by the reinforcing layer can be remarkably obtained.

  Further, the pneumatic tire of the present invention includes an inner liner on a tire inner circumferential surface inside the tire radial direction of the carcass layer, and the inner liner is a thermoplastic resin, or a thermoplastic resin blended with an elastomer component. It is composed of a plastic elastomer composition and also serves as the reinforcing layer.

  According to this pneumatic tire, since the inner liner also serves as the reinforcing layer, it is possible to suppress a situation in which the tire weight and the tire radial thickness are increased while obtaining the function of the reinforcing layer.

  The pneumatic tire of the present invention is applied to a pneumatic tire for passenger cars, and the storage layer has a storage elastic modulus E1 of 50 [MPa] or more and 150 [MPa] or less, and the thickness t of the reinforcement layer is 0. .01 [mm] or more and 0.3 [mm] or less.

  According to this pneumatic tire, the storage elastic modulus E1 of the reinforcing layer is set to 50 [MPa] to 150 [MPa], and the thickness t of the reinforcing layer is set to 0.01 [mm] to 0.3 [mm]. When applied to a pneumatic tire for passenger cars, it is preferable to obtain the effect of the reinforcing layer remarkably.

  The pneumatic tire of the present invention is applied to a heavy load pneumatic tire, the storage elastic modulus E1 of the reinforcing layer is 200 [MPa] or more and 500 [MPa] or less, and the thickness t of the reinforcing layer is 0. .01 [mm] or more and 0.2 [mm] or less.

  According to this pneumatic tire, the storage elastic modulus E1 of the reinforcing layer is 200 [MPa] or more and 500 [MPa] or less, and the thickness t of the reinforcing layer is 0.01 [mm] or more and 0.2 [mm] or less. When applied to a heavy-duty pneumatic tire, it is preferable to obtain a remarkable effect of the reinforcing layer.

  The pneumatic tire according to the present invention can improve riding comfort performance while defining the range of the carcass strength coefficient of the carcass layer.

1 is a meridional cross-sectional schematic view of a pneumatic tire according to Embodiment 1 of the present invention. FIG. 2 is a meridional cross-sectional schematic view illustrating the arrangement of the carcass layer and the reinforcing layer. FIG. 3 is a meridional cross-sectional schematic view illustrating the arrangement of the carcass layer and the reinforcing layer. FIG. 4 is a meridional cross-sectional schematic view illustrating the arrangement of the carcass layer and the reinforcing layer. FIG. 5 is a meridional cross-sectional schematic view illustrating the arrangement of the carcass layer and the reinforcing layer. FIG. 6 is a meridional cross-sectional schematic view illustrating the arrangement of the carcass layer and the reinforcing layer. FIG. 7 is a meridional cross-sectional schematic view illustrating the arrangement of the carcass layer and the reinforcing layer. FIG. 8 is a meridional cross-sectional schematic view illustrating the arrangement of the carcass layer and the reinforcing layer. FIG. 9 is a meridional cross-sectional schematic view illustrating the arrangement of the carcass layer and the reinforcing layer. FIG. 10 is a meridional cross-sectional schematic view illustrating the arrangement of the carcass layer and the reinforcing layer. FIG. 11 is a meridional cross-sectional schematic view illustrating the arrangement of the carcass layer and the reinforcing layer. FIG. 12 is a meridional cross-sectional schematic view illustrating the arrangement of the carcass layer and the reinforcing layer. FIG. 13 is a chart showing the results of the performance test of the pneumatic tire according to the example of the present invention.

  Embodiments of the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. The constituent elements of this embodiment include those that can be easily replaced by those skilled in the art or those that are substantially the same. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

  In the following description, the tire radial direction refers to a direction orthogonal to the rotational axis (not shown) of the pneumatic tire, and the tire radial inner side refers to the side toward the rotational axis in the tire radial direction, the tire radial outer side, and 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 is the side toward the tire equatorial plane C in the tire width direction, and the outer side in the tire width direction is the tire equatorial plane C in the tire width direction. The side away from. The tire equator plane C is a plane that is orthogonal to the rotational axis of the pneumatic tire and passes through the center of the tire width of the pneumatic tire. 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 C in the tire width direction. The tire equator line is a line on the tire equator plane C along the circumferential direction of the pneumatic tire. In the present embodiment, the same sign “C” as that of the tire equator plane is attached to the tire equator line.

  FIG. 1 is a meridional cross-sectional schematic view of a pneumatic tire according to the present embodiment. As shown in FIG. 1, the pneumatic tire according to the present embodiment includes a tread portion 2, shoulder portions 3 on both sides of the tread portion 2, and sidewall portions 4 and bead portions 5 successively from the shoulder portions 3. ing. This pneumatic tire includes a carcass layer 6, a belt layer 7, and an inner liner 8.

  The tread portion 2 is exposed to the outside on the outermost side in the tire radial direction of the pneumatic tire, and the surface thereof becomes the contour of the pneumatic tire. 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 has a plurality (five in this embodiment) of ribs defined by a plurality of (four in the present embodiment) circumferential main grooves 22 formed to extend in the tire circumferential direction. 23 is provided. Although not shown in the drawing, the rib 23 may be provided with a lug groove that extends in the tire width direction and that opens at one end or both ends in the circumferential main groove 22.

  The shoulder portion 3 is a portion on both outer sides in the tire width direction of the tread portion 2. The sidewall portion 4 is exposed at the outermost side in the tire width direction of the pneumatic tire. 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 disposed in a space formed by folding the end of the carcass layer 6 in the tire width direction at the position of the bead core 51.

  The carcass layer 6 is configured such that each tire width direction end portion is folded back from the tire width direction inner side to the tire width direction outer side by a pair of bead cores 51 and is wound around in a toroidal shape in the tire circumferential direction. It is. The carcass layer 6 includes a plurality of reinforcement cords (not shown) such as organic fibers (nylon, polyester, etc.) and steel, and is covered with a carcass coat rubber. At least one carcass layer 6 is provided. In the case of the single carcass layer 6, the reinforcing cord has a tire circumferential direction, that is, an angle with respect to the tire equator line C is set to approximately 90 [deg].

  The belt layer 7 is composed of at least one layer. 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. The belt layer 7 is formed by coating a cord such as organic fiber (nylon, polyester, etc.) or steel with a coat rubber. When the belt layer 7 is one layer, the cord is provided in the tire circumferential direction, that is, parallel to the tire equator line C. In the pneumatic tire of the present embodiment, as shown in FIG. 1, the belt layer 7 has a multilayer structure in which belt layers 71 and 72 are laminated. The belt layers 71 and 72 are provided such that the cords are provided at a predetermined angle with respect to the tire circumferential direction, that is, the tire equator line C, and the cords cross each other.

  The inner liner 8 has a sheet shape or a film shape with low gas permeability, and is disposed on the inner side in the tire radial direction of the carcass layer 6 and on the tire inner peripheral surface of the pneumatic tire.

  As described above, the pneumatic tire according to the present embodiment includes a carcass layer 6 in which a plurality of reinforcing cords are arranged in the tire circumferential direction and both end portions in the tire width direction are extended to the bead cores 51 arranged in the bead portions 5. The belt layer 7 is provided with at least one layer provided on the outer side in the tire radial direction of the carcass layer 6 in the tread portion 2.

  And in this pneumatic tire, the range which is 5 [%] or more and 95 [%] or less of the tire width direction maximum dimension W1 of the belt layer 7 from the tire width direction end of the belt layer 7. For the carcass layer 6 of W2, [carcass strength coefficient K [N / mm · kPa]] = [number of reinforcing cords driven [lines / mm]] × [reinforcing cord strength [N / lines]] × [number of carcass layers ] The carcass strength coefficient K of the carcass layer 6 defined by the equation of [maximum air pressure [kPa]] is set to 0 [N / mm · kPa] <K <0.35 [N / mm · kPa].

  The maximum width W1 in the tire width direction of the belt layer 7 is the dimension in the tire width direction of the belt layer having the maximum width in the tire width direction in the case of the belt layer 7 having a multilayer structure. Further, the position P from 5 [%] to 95 [%] of the tire width direction maximum dimension W1 of the belt layer 7 from the tire width direction end of the belt layer 7 is within the tire width direction maximum dimension W1 of the belt layer 7. , Both end positions in a range of 5 [%] to 95 [%] are shown. Then, one end in the tire width direction of the belt layer 7 is defined as a position P, and a range on the inner side in the tire width direction from the one end in the tire width direction is 5 [%] or more and 95 [%] or less of the maximum width W1 of the belt layer 7 in the tire width direction. It is also included.

  The carcass strength coefficient K = 0 means a configuration in which the carcass layer 6 is divided, and in this configuration, a divided portion of the carcass layer 6 may expand at the time of molding, and the tread thickness may become uneven. Therefore, if the carcass strength coefficient K of the carcass layer 6 is set to 0 [N / mm · kPa] <K, the carcass layer 6 is prevented from expanding and the tread thickness uniformity tends to be improved. On the other hand, when the carcass strength coefficient K ≧ 0.35, the number of reinforcing cords to be driven, the strength of the reinforcing cords, or the number of carcass layers 6 increases, and the tire weight increases and the riding comfort tends to decrease. Therefore, according to this pneumatic tire, the carcass strength coefficient K of the carcass layer 6 is set to 0 [N / mm · kPa] <K <0.35 [N / mm] in a predetermined range in the tire width direction by the belt layer 7. By setting it as kPa], it becomes possible to maintain the riding comfort equivalent to the form in which the carcass layer 6 is divided and to improve the uniformity of the tread thickness.

  If the carcass strength coefficient K of the carcass layer 6 is 0.15 [N / mm · kPa] ≦ K ≦ 0.34 [N / mm · kPa], the carcass layer 6 can be prevented from having an expanded diameter, and the tread. This is preferable because the thickness uniformity tends to be further improved, and the increase in tire weight and the decrease in ride comfort are further suppressed.

  By the way, the above-mentioned range of the carcass strength coefficient K of the carcass layer 6 is lower than that of a general pneumatic tire, and the out-of-plane bending rigidity is reduced. Because the lift at the distance tends to cause variations in the carcass cord interval and the uniformity tends to decrease, vibrations may occur during traveling on a flat road, which may deteriorate the riding comfort.

  Therefore, the pneumatic tire according to the present embodiment is formed of a thermoplastic resin or a thermoplastic elastomer composition obtained by blending an elastomer component in a thermoplastic resin and has no cord in at least a part of the range W2. A reinforcing layer 9 is arranged.

  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 / tetramethyleneglycol Copolymer, PET / PEI copolymer, polyarylate (PAR), polybutylene naphthalate (PBN), liquid crystal 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 resins [for example, polymethyl methacrylate (PMMA), polyethyl methacrylate, ethylene ethyl acrylate copolymer (EEA), ethylene acrylic acid copolymer (EAA), ethylene methyl acrylate resin (EMA)], polyvinyl Resins [eg, 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 the present embodiment include diene rubbers and hydrogenated products thereof [for example, NR, IR, epoxidized natural rubber, SBR, BR (high cis BR and low cis BR), NBR, hydrogenation. NBR, hydrogenated SBR], olefin 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 Compound, 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 Ethylene (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 silicone rubber, fluorine-containing phosphazene rubber), thermoplastic elastomer (eg, styrene elastomer, olefin elastomer, polyester elastomer, And urethane elastomers and polyamide elastomers).

  Moreover, in the thermoplastic elastomer composition used in the present embodiment, the composition ratio of the thermoplastic resin component (A) and the elastomer component (B) may be appropriately determined depending on the balance of film thickness and flexibility. The preferred range is 10/90 to 90/10, more preferably 20/80 to 85/15 (weight ratio).

  In the thermoplastic elastomer composition according to the present embodiment, in addition to the essential components (A) and (B), as a third component, other polymers such as a compatibilizing agent and a compounding agent can be mixed. The purpose of mixing other polymers is to improve the compatibility between the thermoplastic resin component and the elastomer component, to improve the film molding processability of the material, to improve heat resistance, to reduce costs, etc. Examples of the material used for this include polyethylene, polypropylene, polystyrene, ABS, SBS, and polycarbonate.

The thermoplastic elastomer composition is prepared by melt-kneading a thermoplastic resin and an elastomer (unvulcanized material in the case of rubber) in advance using a twin-screw kneading extruder or the like, and adding an elastomer component in the thermoplastic resin forming a continuous phase. It is obtained by dispersing. When the elastomer component is vulcanized, a vulcanizing agent may be added under kneading to dynamically vulcanize the elastomer. Further, various compounding agents (excluding the vulcanizing agent) to the thermoplastic resin or the elastomer component may be added during the kneading, but are preferably mixed in advance before kneading. The kneading machine used for kneading the thermoplastic resin and the elastomer is not particularly limited, and examples thereof include a screw extruder, a kneader, a Banbury mixer, and a biaxial kneading extruder. Among these, it is preferable to use a twin-screw kneading extruder for kneading the resin component and the rubber component and for dynamic vulcanization of the rubber component. Further, two or more types of kneaders may be used and kneaded sequentially. As conditions for melt-kneading, the temperature may be higher than the temperature at which the thermoplastic resin melts. The shear rate during kneading is preferably 2500 to 7500 sec- ¹ . The entire kneading time is from 30 seconds to 10 minutes, and when a vulcanizing agent is added, the vulcanization time after addition is preferably from 15 seconds to 5 minutes. The thermoplastic elastomer composition produced by the above method is formed into a film by molding with a resin extruder or calender molding. The method for forming a film may be a method of forming a film of a normal thermoplastic resin or thermoplastic elastomer.

  The thin film of the thermoplastic elastomer composition thus obtained has a structure in which the elastomer is dispersed as a discontinuous phase in a thermoplastic resin matrix. By adopting the dispersion structure in such a state, it is possible to set the Young's modulus in a range of 1 to 500 MPa and to impart appropriate rigidity as a tire constituent member.

  2 to 12 are meridional cross-sectional schematic views illustrating the arrangement of the carcass layer and the reinforcing layer. The pneumatic tire shown in FIG. 1 and FIG. 2 is provided with a reinforcing layer 9 on the inner side in the tire radial direction of the carcass layer 6 and between the inner liner 8. The pneumatic tire shown in FIG. 3 is provided with a reinforcing layer 9 as an inner liner 8 on the inner circumferential surface of the pneumatic tire, which is on the inner side in the tire radial direction of the carcass layer 6. In the pneumatic tire shown in FIG. 4, a reinforcing layer 9 is provided between the carcass layer 6 and the belt layer 7 on the outer side in the tire radial direction.

  The pneumatic tire shown in FIG. 5 to FIG. 8 is provided with the end portion of the carcass layer 6 folded back to the outer side in the tire width direction by the bead core 51 extending to the inner side in the tire radial direction of the belt layer 7. A range W2 is defined between the end portions. The pneumatic tire shown in FIG. 5 is provided with a reinforcing layer 9 on the inner side in the tire radial direction of the carcass layer 6 and between the inner liner 8. The pneumatic tire shown in FIG. 6 is provided with a reinforcing layer 9 as an inner liner 8 on the inner circumferential surface of the pneumatic tire, which is on the inner side in the tire radial direction of the carcass layer 6. In the pneumatic tire shown in FIG. 7, a reinforcing layer 9 is provided between the carcass layer 6 and the belt layer 7 on the outer side in the tire radial direction. In the pneumatic tire shown in FIG. 8, a reinforcing layer 9 is provided between end portions of the carcass layer 6.

  Further, in the pneumatic tire shown in FIGS. 9 to 12, the end portion of the carcass layer 6 that is folded back inward in the tire width direction by the bead core 51 extends to the inner side in the tire radial direction of the belt layer 7. A range W2 is defined between the end portions. In the pneumatic tire shown in FIG. 9, the reinforcing layer 9 is provided between the carcass layer 6 and the inner liner 8 on the inner side in the tire radial direction. The pneumatic tire shown in FIG. 10 is provided with a reinforcing layer 9 as an inner liner 8 on the inner circumferential surface of the pneumatic tire on the inner side in the tire radial direction of the carcass layer 6. In the pneumatic tire shown in FIG. 11, a reinforcing layer 9 is provided between the carcass layer 6 and the belt layer 7 on the outer side in the tire radial direction. In the pneumatic tire shown in FIG. 12, a reinforcing layer 9 is provided between end portions of the carcass layer 6.

  As described above, the pneumatic tire according to the present embodiment includes a carcass layer 6 in which a plurality of reinforcing cords are arranged in the tire circumferential direction and both end portions in the tire width direction are extended to the bead cores 51 arranged in the bead portions 5. In the pneumatic tire provided with at least one belt layer 7 provided on the outer side in the tire radial direction of the carcass layer 6 in the tread portion 2, the inner side in the tire width direction from the tire width direction end of the belt layer 7, [Carcass strength coefficient K [N / mm · kPa]] = [Number of reinforcing cords driven [lines / mm] in a range W2 of 5 [%] to 95 [%] of the maximum dimension W1 in the tire width direction of the belt layer 7 ]] [Reinforcing cord strength [N / piece]] × [number of carcass layers] ÷ [maximum air pressure [kPa]], the carcass strength coefficient K of the carcass layer is defined as 0 [N / mm]・ KP ] <K <0.35 [N / mm · kPa], and at least part of the range W2 is composed of a thermoplastic resin or a thermoplastic elastomer composition obtained by blending an elastomer component in a thermoplastic resin. Layer 9 is arranged.

  According to this pneumatic tire, by defining the range of the carcass strength coefficient K of the carcass layer 6, it is possible to improve the riding comfort when riding over a step. In addition, the reinforcement layer 9 prevents the occurrence of variations in the carcass cord spacing due to lift during molding, suppresses the decrease in uniformity, and prevents vibration when driving on flat roads, improving ride comfort. It becomes possible to do.

  In the pneumatic tire according to the present embodiment, the thermoplastic resin or the thermoplastic elastomer composition constituting the reinforcing layer 9 has a storage elastic modulus E1 [MPa] of 600 [MPa] or less and a thickness t [ mm] is preferably 3 mm or less. When the storage elastic modulus E1 [MPa] and the thickness t [mm] of the reinforcing layer 9 exceed the ranges, the weight of the reinforcing layer 9 increases and the tire weight tends to increase.

  In particular, in the pneumatic tire of the present embodiment, the thermoplastic resin or thermoplastic elastomer composition constituting the reinforcing layer 9 has a storage elastic modulus E1 [MPa] and a thickness t [mm] of 6.7 t + E1−. It is preferable that 20 ≧ 0, 200t + E1−600 ≦ 0, E1> 0, and t> 0.

  By setting it in this range, it is possible to prevent an increase in the weight of the reinforcing layer 9 and suppress an increase in the tire weight, and it is possible to prevent the reinforcing layer 9 from increasing in hardness and to improve the moldability of the reinforcing layer 9. It becomes possible to maintain.

  In the pneumatic tire of the present embodiment, it is preferable that the reinforcing layer 9 is disposed in the range W3 in the tire width direction of 60% to 120% of the range W2.

  By arranging the reinforcing layer 9 in the range W3 in the tire width direction of 60 [%] or more and 120 [%] or less of the range W2, the effect of the reinforcing layer 9 can be remarkably obtained.

  The pneumatic tire according to the present embodiment includes an inner liner 8 on the tire inner circumferential surface on the inner side in the tire radial direction of the carcass layer 6, and the inner liner 8 is an elastomer component in the thermoplastic resin or the thermoplastic resin. It is preferable that it is comprised with the thermoplastic elastomer composition which blended, and also serves as the reinforcement layer 9.

  Since the inner liner 8 also serves as the reinforcing layer 9, it is possible to prevent the tire weight and the tire radial thickness from increasing while obtaining the function of the reinforcing layer 9.

  Further, the pneumatic tire of the present embodiment is applied to a pneumatic tire for passenger cars, the storage elastic modulus E1 of the reinforcing layer 9 is 50 [MPa] or more and 150 [MPa] or less, and the thickness t of the reinforcing layer 9 Is preferably 0.01 [mm] or more and 0.3 [mm] or less.

  For the passenger car, the storage elastic modulus E1 of the reinforcing layer 9 is 50 [MPa] or more and 150 [MPa] or less, and the thickness t of the reinforcing layer 9 is 0.01 [mm] or more and 0.3 [mm] or less. When applied to a pneumatic tire, it is preferable to obtain the effect of the reinforcing layer 9 remarkably.

  Further, the pneumatic tire of the present embodiment is applied to a heavy load pneumatic tire, the storage elastic modulus E1 of the reinforcing layer 9 is 200 [MPa] or more and 500 [MPa] or less, and the thickness t of the reinforcing layer 9 Is preferably 0.01 [mm] or more and 0.2 [mm] or less.

  For the heavy load, the storage elastic modulus E1 of the reinforcing layer 9 is set to 200 [MPa] to 500 [MPa] and the thickness t of the reinforcing layer 9 is set to 0.01 [mm] to 0.2 [mm]. When applied to a pneumatic tire, it is preferable to obtain the effect of the reinforcing layer 9 remarkably.

  In the present embodiment, performance tests relating to riding comfort (step climbing), riding comfort (flat road), and formability were performed for a plurality of types of pneumatic tires having different conditions (see FIG. 13).

  In this performance test, a pneumatic tire having a tire size of 195 / 65R15 was assembled to a regular rim, filled with a regular internal pressure (220 [kPa]), and mounted on a test vehicle (domestic 2.0-liter class passenger car). The regular rim here refers to “standard rim” defined in JATMA, “Design Rim” defined in TRA, or “Measuring Rim” defined in ETRTO. The normal 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.

  In the performance test of ride comfort (over the step), the above test vehicle runs on a straight test course with unevenness of 10 [mm] at 60 [km / h], and one skilled driver has 5 levels of sensuality. Evaluation was performed. This evaluation shows an average of three times as an index based on the conventional example as a reference (100), and the higher this index, the better the ride comfort.

  In the performance test of ride comfort (flat road), the above test vehicle runs on a flat test course at 60 [km / h], and one expert driver performs a five-step sensory evaluation on running vibration. went. This evaluation shows an average of three times as an index based on the conventional example as a reference (100), and the higher this index, the better the ride comfort.

  In addition, the evaluation of riding comfort is that the index of evaluation of overstepping and the index of adding evaluation of flat road is compared with the conventional 200, and the riding comfort is excellent by exceeding the index of 200. To do.

  In the moldability test, it was examined whether or not the diameter of the molding drum was enlarged during tire molding. If the diameter of the molding drum is increased, the moldability is preferably indicated by ◯, and if the diameter of the molding drum is not increased, the moldability is poor and indicated by x.

  The conventional pneumatic tire has the carcass strength coefficient K in the range W2 within the specified range, but does not include a reinforcing layer. The pneumatic tire of the comparative example has a carcass strength coefficient K in the range W2 outside the specified range, and includes a reinforcing layer. On the other hand, the pneumatic tires of Examples 1 to 6 have the carcass strength coefficient K in the range W2 as a specified range and include a reinforcing layer. Among these, in the pneumatic tire of Example 2, the thickness t of the reinforcing layer is set to be relatively large. In the pneumatic tire of Example 3, the storage elastic modulus E1 of the reinforcing layer is set to be relatively large. In the pneumatic tire of Example 4, the carcass strength coefficient K in the range W2 is set to be relatively small. In the pneumatic tire of Example 5, the reinforcing layer is configured as an inner liner. In the pneumatic tire of Example 6, a reinforcing layer is provided inside the carcass layer whose folded end extends to the belt layer.

  As shown in the test results of FIG. 13, it can be seen that the pneumatic tires of Examples 1 to 6 are excellent in ride comfort and maintain moldability.

2 Tread portion 5 Bead portion 51 Bead core 6 Carcass layer 7 Belt layer 8 Inner liner 9 Reinforcing layer

Claims (6)

A plurality of reinforcing cords are arranged in the tire circumferential direction, and at least one layer is provided on the outer side in the tire radial direction of the carcass layer in the tread portion, and a carcass layer that extends to both bead cores at both ends in the tire width direction. In a pneumatic tire provided with a belt layer formed,
[Carcass strength coefficient K] in a range W2 that is 5% to 95% of the maximum width W1 of the belt layer in the tire width direction from the end in the tire width direction of the belt layer. [N / mm · kPa]] = [Number of reinforcing cords driven [number / mm]] × [Strength of reinforcing cord [N / number]] × [Number of carcass layers] ÷ [Maximum air pressure [kPa]] The carcass strength coefficient K of the defined carcass layer is set to 0 [N / mm · kPa] <K <0.35 [N / mm · kPa] without changing the number of layers in the range W2.
The pneumatic tire is characterized in that a reinforcing layer made of a thermoplastic resin or a thermoplastic elastomer composition obtained by blending an elastomer component in a thermoplastic resin is disposed in at least a part of the range W2.   The thermoplastic resin or thermoplastic elastomer composition constituting the reinforcing layer has a storage elastic modulus E1 [MPa] and a thickness t [mm] of 6.7 t + E1-20 ≧ 0, 200t + E1-600 ≦ 0, E1>. The pneumatic tire according to claim 1, wherein the relationship is 0, t> 0.   The pneumatic tire according to claim 1 or 2, wherein the reinforcing layer is disposed in a range in the tire width direction of 60% to 120% of the range W2.   An inner liner is provided on the inner circumferential surface of the tire in the tire radial direction of the carcass layer, and the inner liner is made of a thermoplastic resin or a thermoplastic elastomer composition obtained by blending an elastomer component in a thermoplastic resin, and the reinforcement The pneumatic tire according to any one of claims 1 to 3, wherein the pneumatic tire also serves as a layer.   The reinforcing elastic layer has a storage elastic modulus E1 of 50 [MPa] or more and 150 [MPa] or less, and the reinforcing layer has a thickness t of 0.01 [mm] or more and 0.3 [ mm] or less, The pneumatic tire according to any one of claims 1 to 4.   It is applied to a heavy load pneumatic tire, the storage elastic modulus E1 of the reinforcing layer is 200 [MPa] or more and 500 [MPa] or less, and the thickness t of the reinforcing layer is 0.01 [mm] or more and 0.2 [ mm] or less, The pneumatic tire according to any one of claims 1 to 4.

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