Tire

Abstract

Provided is a tire having low rolling resistance and reduced passage noise. A tire (10) is provided with at least one belt layer (2) and at least one belt reinforcing layer (3) disposed on the outside in the tire radial direction in a tread portion (11). The belt reinforcing layer is formed by coating rubber on reinforcing cords, the reinforcing cords are aligned such that the cord direction substantially becomes the tire circumferential direction, and the value of the circumferential stiffness S per 100 mm unit width of the belt reinforcing layer defined by formula (1) is 250-400. And the storage modulus E'of the coating rubber measured under the conditions of a temperature of 24 DEG C, an amplitude of + / -1%, and a frequency of 52 Hz is 6.0 MPa or less. S = sc * N (1) In the formula, sc is the cord stiffness (mN / (dtex *%)) of the reinforcing cords of the belt reinforcing layer at a temperature of 24 DEG C and a humidity of 55%, and N is the arrangement density (cords / 100 mm) of the reinforcing cords of the belt reinforcing layer.

Description

TECHNICAL FIELD

[0001] The present application relates to a tire, and more particularly to a passenger vehicle tire, particularly a pneumatic tire for a passenger vehicle, in which a belt reinforcing layer for reinforcing a tread ground contact surface is improved. BACKGROUND

[0002] Generally, a pneumatic tire such as a passenger vehicle tire has a basic structure in which a carcass extending in a ring shape across a pair of bead portions is used as a skeleton, and a tread ground contact surface is reinforced by two or more belt layers arranged so that the cord directions are staggered between the layers. Further, one or more belt reinforcing layers in which cords are arranged substantially in the tire circumferential direction are further provided on the tire radial direction outer side of the belt layers.

[0003] As the reinforcing cords of such a belt reinforcing layer, in recent years, polyethylene terephthalate (PET) fiber, which is high in elasticity and low in cost compared to nylon, has been used from the viewpoint of achieving an improvement in the performance of the tire and a reduction in cost (for example, see Patent Document 1).

[0004] PRIOR ART DOCUMENTS

[0005] PATENT DOCUMENTS

[0006] Patent Document 1: Japanese Patent Application Laid-Open (kokai) No. 2005-112065 (Japanese Patent No. 4397207) SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] By applying PET fiber as the reinforcing cords of the belt reinforcing layer, the belt reinforcing layer is high in elasticity, and it is possible to reduce the rolling resistance of the tire, but on the other hand, there is a problem in that the noise in the high frequency region, so-called passing noise during running, deteriorates. In the tire disclosed in Patent Document 1, there is no investigation of the problem of passing noise.

[0009] Therefore, an object of the present application is to provide a tire that is low in rolling resistance and reduced in passing noise.

[0010] SOLUTION TO PROBLEM

[0011] As a result of intensive studies by the present inventors and others, it has been found that the above problem can be solved by causing the physical properties of the belt reinforcing layer to satisfy prescribed conditions, and the present application has thus been completed. That is, the present application is as described below.

[0012] (1) A tire characterized by comprising at least one belt layer in a tread portion, and at least one belt reinforcing layer disposed on the tire radial direction outer side of the belt layer,

[0013] The belt reinforcing layer is formed by coating a rubber-coated reinforcing cord, the reinforcing cord is aligned in a cord direction substantially in a tire circumferential direction, a value of a circumferential rigidity S of the belt reinforcing layer per 100 mm unit width defined by the following formula (1) is 250 or more and 400 or less, and a storage modulus E' of the rubber coating measured under conditions of a temperature of 24°C, an amplitude of ±1%, and a frequency of 52 Hz is 6.0 MPa or less,

[0014] S = sc x N (1)

[0015] In the formula, sc is a cord rigidity (mN / (dtex%)) of the reinforcing cord of the belt reinforcing layer under conditions of a temperature of 24°C and a humidity of 55%, and N is an arrangement density (root / 100 mm) of the reinforcing cord of the belt reinforcing layer.

[0016] Thus, a tire with low rolling resistance and reduced passing noise can be achieved.

[0017] (2) The tire according to (1), wherein a value of a loss index L of the rubber coating contained in the belt reinforcing layer per 100 mm unit width defined by the following formula (2) is 4.00 or less,

[0018] L = tan δ x ((100 x D) - π(D / 2) 2 x N) (2)

[0019] In the formula, tan δ is a value of a loss tangent of the rubber coating measured under conditions of a temperature of 24°C, an initial strain of 6%, an amplitude of ±1%, and a frequency of 52 Hz, D is a diameter (mm) of a circumscribed circle of the reinforcing cord, and N is an arrangement density (root / 100 mm) of the reinforcing cord in the belt reinforcing layer.

[0020] Thus, the rolling resistance can be reduced, and the effects of the present application can be more favorably obtained.

[0021] (3) The tire according to (1) or (2), wherein a rubber composition used in the rubber coating contains natural rubber and styrene-butadiene rubber as a rubber component, and 70 mass% or more of the natural rubber is contained in 100 mass parts of the rubber component.

[0022] Thus, the storage modulus E' of the rubber composition can be suppressed, and the effect of reducing the passing noise can be further improved.

[0023] (4) The tire according to (3), wherein the styrene-butadiene rubber is non-oil-extended.

[0024] Thus, tan δ (24°C) of the rubber composition can be suppressed, and the effect of reducing the rolling resistance can be further improved.

[0025] (5) The tire according to any one of (1) to (4), wherein the rubber composition used in the coated rubber contains 30 to 60 parts by mass of carbon black having a nitrogen adsorption specific surface area (N2SA) of 40 m2 / g or less, relative to 100 parts by mass of a rubber component. 2

[0026] Thus, the storage modulus E' of the rubber composition can be suppressed, and the effect of reducing the noise can be further improved.

[0027] (6) The tire according to any one of (1) to (5), wherein the rubber composition used in the coated rubber does not contain an oil component derived from a polymer.

[0028] Thus, tan δ (24°C) of the rubber composition can be suppressed, and the effect of reducing the rolling resistance can be further improved.

[0029] (7) The tire according to any one of (1) to (6), wherein the oil component in the rubber composition used in the coated rubber is 0.2% by mass or less.

[0030] Thus, tan δ (24°C) of the rubber composition can be further suppressed, and the effect of reducing the rolling resistance can be further improved.

[0031] (8) The tire according to any one of (1) to (7), wherein the reinforcing cord is composed of polyethylene terephthalate fibers.

[0032] Thus, the belt reinforcing layer can be highly elasticized, and the rolling resistance of the tire can be further reduced.

[0033] Effects of the Invention

[0034] According to the present application, by adopting the above configuration, a tire having a low rolling resistance and reduced noise can be achieved. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is a width direction sectional view of a passenger car tire illustrating an example of the present application.

[0036] Figure 2 is an explanatory diagram of a provision regarding the sectional area of the coated rubber contained in each 100 mm unit width of the belt reinforcing layer.

[0037] Figure 3 is a schematic diagram for explaining the calculation method of the modulus of elasticity at 7% elongation of the cord. DETAILED DESCRIPTION

[0038] Hereinafter, the embodiments of the present application will be explained in detail with reference to the drawings. ​

[0039] Note that the compounds and materials described in the present specification can be derived in part or entirely from fossil resources, or from biological resources such as plant resources, or from recycled resources such as used tires. In addition, they can be derived from a mixture of any two or more of fossil resources, biological resources, and recycled resources.

[0040] Figure 1 is a width direction sectional view showing an example of the tire of the present application. CL in the drawing indicates a tire equator line. The illustrated tire 10 is a passenger vehicle tire, and has a tread portion 11 formed in a ring shape, and a pair of side portions 12 and a bead portion 13 disposed in this order on the inner side in the tire radial direction thereof. In addition, the illustrated tire 10 has a carcass 1 extending in a ring shape across the pair of bead portions 13 as a skeleton, and has at least one belt layer 2 on the outer side in the tire radial direction of the carcass 1 in the tread portion, and at least one belt reinforcing layer 3 disposed on the outer side in the tire radial direction thereof.

[0041] Among them, the belt reinforcing layer 3 contains a circumferential belt formed by coating an enhanced cord with rubber, and the enhanced cord is aligned in the cord direction so as to become substantially the tire circumferential direction. In the tire of the present application, it is important that the belt reinforcing layer 3 satisfies the following conditions.

[0042] That is, in the tire of the present application, the circumferential stiffness S of the belt reinforcing layer 3 per 100 mm unit width defined by the following formula (1) is 250 or more and 400 or less, and the storage modulus E' of the coated rubber of the belt reinforcing layer 3 measured under the conditions of a temperature of 24°C, an amplitude of ±1%, and a frequency of 52 Hz is 6.0 MPa or less,

[0043] S = sc x N (1)

[0044] In formula (1), sc is the cord stiffness (mN / (dtex%)) of the enhanced cord of the belt reinforcing layer 3 under the conditions of a temperature of 24°C and a humidity of 55%, and N is the arrangement density (root / 100 mm) of the enhanced cord of the belt reinforcing layer 3.

[0045] Here, formula (1) defines the value of the circumferential stiffness S of the belt reinforcing layer 3 per 100 mm unit width as the value obtained by multiplying the cord stiffness of each enhanced cord of the belt reinforcing layer 3 by the number of enhanced cords contained in each 100 mm unit width. Since the stiffness is greatly different between the enhanced cord and the coated rubber, in the present application, the cord stiffness of the enhanced cord is used to define the circumferential stiffness of the belt reinforcing layer 3.

[0046] According to the present application, by setting the stiffness of the belt reinforcing layer 3 to an appropriate range by satisfying the above condition with respect to the value of the circumferential stiffness S per unit width of the belt reinforcing layer 3 and the value of the storage modulus E' of the coated rubber of the belt reinforcing layer 3, a tire that suppresses the deterioration of the passing noise while reducing the rolling resistance can be realized.

[0047] The value of the circumferential stiffness S per 100 mm unit width of the belt reinforcing layer 3 needs to be 250 or more and 400 or less, and is preferably 280 or more and 350 or less. If the value of the circumferential stiffness S is less than 250, a good low rolling resistance cannot be obtained. If the value of the circumferential stiffness S exceeds 400, the passing noise does not sufficiently decrease.

[0048] Here, in the above formula (1), the cord stiffness sc (mN / (dtex-%)) of the reinforcing cord of the belt reinforcing layer 3 can be specifically determined as follows. That is, a tensile test of the reinforcing cord can be performed under the conditions of a clamping interval of 250 mm and a tensile speed of 300 ± 20 mm / minute in a test environment of a temperature of 24°C and a humidity of 55% in accordance with "Chemical Fiber Tire Cord Test Method" prescribed in JIS-L 1017, and the average value of the slope at 1 to 2% elongation in the load-elongation curve is obtained as the cord stiffness (mN / %), and the value of sc (mN / (dtex-%)) is obtained in the form of the value obtained by further dividing the fineness (dtex) of the reinforcing cord.

[0049] In addition, the storage modulus E' of the coated rubber of the belt reinforcing layer 3 is a value measured under the conditions of a temperature of 24°C, an amplitude of ±1%, and a frequency of 52 Hz, and needs to be 6.0 MPa or less, and is preferably 5.0 MPa or more and 5.5 MPa or less. If the storage modulus E' exceeds 6.0 MPa, the passing noise cannot sufficiently decrease.

[0050] In the tire of the present application, the value of the loss index L of the coated rubber contained in the belt reinforcing layer 3 per 100 mm unit width is preferably 4.00 or less, which is defined by the following formula (2). Here, the width of the belt reinforcing layer 3 refers to the width of the belt reinforcing layer 3 measured in the tire width direction along the belt reinforcing layer 3.

[0051] L = tan δ x ((100 x D) - π(D / 2) 2 x N) (2)

[0052] In formula (2), tan δ is the value of the loss tangent of the coated rubber of the belt reinforcing layer 3 measured under the conditions of a temperature of 24°C, an initial strain of 6%, an amplitude of ±1%, and a frequency of 52 Hz, D is the diameter (mm) of the circumscribed circle of the reinforcing cord of the belt reinforcing layer 3, and N is the arrangement density (root / 100 mm) of the reinforcing cord in the belt reinforcing layer 3.

[0053] Figure 2 An explanatory diagram showing the prescribed amount of coated rubber contained in the belt reinforcing layer 3 per 100 mm width. Figure 2 The belt reinforcing layer 3 shown is formed by coating the reinforcing cords 31 aligned in one direction with the coated rubber 32. Here, alignment in one direction means a range including manufacturing errors. In the present application, the belt reinforcing layer 3 is not limited to the belt reinforcing layer 3 shown, and can be a belt reinforcing layer 3 in which the reinforcing cords 31 are aligned in one direction and the coated rubber 32 is coated on the reinforcing cords 31. Figure 2 In the present application, the cross-sectional area per 100 mm unit width of the belt reinforcing layer 3 is shown as the portion surrounded by the broken line, and the cross-sectional area of the coated rubber 32 in the belt reinforcing layer 3 is shown by the diagonal line.

[0054] That is, the value of the loss index L of the coated rubber of the belt reinforcing layer 3 is defined by the value of the tangent of the loss angle tan δ (24°C) of the coated rubber 32 of the belt reinforcing layer 3 multiplied by the value of the cross-sectional area of the coated rubber 32 contained in the belt reinforcing layer 3 per 100 mm unit width. The lower the tan δ (24°C) of the coated rubber 32, and the smaller the cross-sectional area of the coated rubber 32, the lower the rolling resistance.

[0055] The value of the loss index L of the coated rubber of the belt reinforcing layer 3 described above is preferably 4.00 or less, and more preferably 2.5 or more and 3.5 or less, because the rolling resistance can be reduced and the effects of the present application can be more favorably obtained when the value is 4.00 or less.

[0056] In the present application, the belt reinforcing layer 3 is not particularly limited as long as the conditions related to the above-described physical properties are satisfied, and the specific constitution thereof is not particularly limited. For example, the following materials can be used.

[0057] The rubber component of the rubber composition used in the coated rubber of the belt reinforcing layer 3 is not particularly limited, and various elastomers can be used. As such an elastomer, natural rubber (NR), isoprene rubber (IR), epoxidized natural rubber, styrene-butadiene rubber (SBR), diene-based rubbers such as butadiene rubber (BR, high-cis BR, and low-cis BR), nitrile-butadiene rubber (NBR), hydrogenated NBR, hydrogenated SBR, and hydrogenates thereof, ethylene-propylene rubber (EPDM, EPM), maleic acid-modified ethylene-propylene rubber (M-EPM), butyl rubber (IIR), copolymers of isobutylene and aromatic vinyl or diene monomers, acrylic rubber (ACM), ionomer, and other olefin-based rubbers, Br-IIR, Cl-IIR, bromide of isobutylene-p-methylstyrene copolymer (Br-IPMS), chloroprene rubber (CR), chlorohydrin rubber (CHR), chlorosulfonated polyethylene rubber (CSM), chlorinated polyethylene rubber (CM), maleic acid-modified chlorinated polyethylene rubber (M-CM), and other halogen-containing rubbers, methylvinylsilicone rubber, dimethylsilicone rubber, methylphenylvinylsilicone rubber, and other silicone rubbers, polysulfide rubber, and other sulfur-containing rubbers, vinylidene fluoride-based rubber, fluorine-containing vinyl ether-based rubber, tetrafluoroethylene-propylene-based rubber, fluorine-containing silicone-based rubber, fluorine-containing phosphazene-based rubber, and other fluororubbers, styrene-based elastomers, olefin-based elastomers, ester-based elastomers, urethane-based elastomers, polyamide-based elastomers, and other thermoplastic elastomers can be used.

[0058] In the present application, the rubber component of the rubber composition used in the coated rubber of the belt reinforcing layer 3 contains natural rubber and styrene-butadiene rubber, and preferably contains 70 parts by mass or more of natural rubber in 100 parts by mass of the rubber component. Thereby, the storage modulus E' of the rubber composition can be suppressed, and a noise reduction effect can be obtained. The content of natural rubber in the rubber composition used in the coated rubber of the belt reinforcing layer 3 is more preferably 70 parts by mass or more and 90 parts by mass or less in 100 parts by mass of the rubber component. The natural rubber can be a modified natural rubber. In the case of a modified natural rubber, for example, a modified natural rubber having a nitrogen content of 0.1 to 0.3% by mass is preferred. In addition, the modified natural rubber is preferably a modified natural rubber from which proteins have been removed by a centrifugal separation process, enzyme treatment, or urea treatment. Furthermore, the modified natural rubber preferably has a phosphorus content of more than 200 ppm and 900 ppm or less.

[0059] In addition, in the present application, as the styrene-butadiene rubber, non-oil-extended styrene-butadiene rubber is preferably used. Thereby, tan δ (24°C) of the rubber composition can be suppressed, and a rolling resistance reduction effect can be obtained.

[0060] Further, in the present application, it is preferable that the rubber composition used in the coated rubber of the belt reinforcing layer 3 contains 30 to 60 parts by mass of carbon black having a nitrogen adsorption specific surface area (N2SA) of 40 m 2 / g or less. Thereby, the storage modulus E' of the rubber composition can be suppressed, and a noise reduction effect can be obtained.

[0061] The nitrogen adsorption specific surface area (N2SA) of the above-mentioned carbon black is preferably 40 m 2 / g or less, more preferably 34 m 2 / g or less, particularly preferably 30 m 2 / g or less. The nitrogen adsorption specific surface area (N2SA) of the above-mentioned carbon black can be 25 m 2 / g or more. Further, the content of the above-mentioned carbon black is preferably 30 to 60 parts by mass, more preferably 40 to 50 parts by mass, with respect to 100 parts by mass of the rubber component. The above-mentioned carbon black can be a reclaimed carbon black. Here, the "reclaimed carbon black" refers to carbon black obtained by recycling from a raw material that is a waste for recycling. Further, as the above-mentioned waste for recycling, there can be cited rubber products (particularly vulcanized rubber products) containing carbon black, such as used rubber and used tires, waste oil, and the like. The "reclaimed carbon black" is different from carbon black manufactured directly from a raw material such as petroleum, natural gas, or the like, that is, carbon black that is not a reclaimed product. Note that "used" here includes not only the case where it is discarded after actual use, but also the case where it is discarded although it has been manufactured, but not actually used.

[0062] In the rubber composition used in the coated rubber of the belt reinforcing layer 3, in addition to the carbon black, sulfur, and vulcanization accelerator, an antioxidant, zinc oxide (zinc white), stearic acid, or the like, which are generally used in rubber products such as tires, can be appropriately mixed. Here, as the mixing amount of the zinc oxide in the above-mentioned rubber composition, it is preferable to be more than 3 parts by mass and less than 5 parts by mass with respect to 100 parts by mass of the rubber component. When the mixing amount of the zinc oxide is 5 parts by mass or more, agglomeration can occur, leading to deterioration of dispersibility, and when it is 3 parts by mass or less, adverse effects on the vulcanization reaction can occur.

[0063] In addition, in the present application, the rubber composition used in the coated rubber of the belt reinforcing layer 3 preferably does not contain a polymer-derived oil component. Here, the absence of a polymer-derived oil component means that the oil component is not directly mixed in the rubber composition as a component contained in the polymer, etc. By making the content of the polymer-derived oil component in the rubber composition used in the coated rubber of the belt reinforcing layer 3 zero, it is possible to suppress the tan δ (24°C) of the rubber composition, and it is possible to obtain a reduction effect of the rolling resistance. More preferably, the oil component in the rubber composition used in the coated rubber of the belt reinforcing layer 3 is set to 0.2% by mass or less. Thus, it is possible to further suppress the tan δ (24°C) of the rubber composition, and it is possible to further improve the reduction effect of the rolling resistance.

[0064] Further, in the present application, the tan δ of the rubber composition used in the coated rubber of the belt reinforcing layer 3, which is measured under the conditions of a temperature of 60°C, an initial strain of 1.5%, an amplitude of ±1%, and a frequency of 52 Hz, is preferably 0.07 or less.

[0065] As the reinforcing cord of the belt reinforcing layer 3, an organic fiber cord can be used. As the material of the organic fiber cord, there is no particular limitation, and polyester such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), nylon (aliphatic polyamide) such as 6-nylon, 6,6-nylon, and 4,6-nylon, rayon, lyocell, and cellulose can be cited. Among them, PET fiber having higher rigidity than nylon cord, etc. is preferable. By using PET fiber as the reinforcing cord of the belt reinforcing layer 3, it is possible to make the belt reinforcing layer 3 highly elastic, and reduce the rolling resistance of the tire.

[0066] The modulus of elasticity at 29.4 N load of the above-mentioned organic fiber cord measured at 160°C is preferably 2.0 mN / (dtex·%) or more, and more preferably 2.5 mN / (dtex·%) or more and 4.5 mN / (dtex·%) or less. Here, the modulus of elasticity at 29.4 N load measured at 160°C is calculated by converting the slope (N / %) of the tangent line at the point corresponding to the load 29.4 N of the load-elongation rate curve of the cord measured at 160°C to the value per 1 dtex.

[0067] Note that the reason for measuring the modulus of elasticity at 160°C is that the temperature inside the tire rises with high-speed running, and at the time of tire failure due to high-speed running, the temperature of the belt reinforcing layer 3 reaches 160°C. In particular, the decrease in the modulus of elasticity of the PET cord at high temperature is large compared to that at normal temperature, and even if the cord is highly elastic at normal temperature, if the modulus of elasticity at high temperature cannot be maintained, the cord cannot exhibit sufficient belt reinforcing effects, that is, the effects of improving durability against protrusions and suppressing protrusion of the belt, and therefore the modulus of elasticity at high temperature is important. By setting the modulus of elasticity of the cord at 29.4 N load at 160°C to 2.0 mN / (dtex% ) or more, it is possible to improve the plunger durability of the tire, and in addition, it is possible to suppress the amount of protrusion of the belt at the time of high-speed running, to reduce stress at the time of tire grounding or ungrounding, and to improve the handling stability of the tire at the time of high-speed running.

[0068] In order to improve the modulus of elasticity of the above-described organic fiber cord at 160°C, it is preferable to perform impregnation treatment at a high tension. By adjusting the tension applied to the cord at the time of impregnation treatment, various modulus of elasticity of the organic fiber cord was produced, and the obtained impregnated cord was coated with an elastomer and used in a belt reinforcing layer to be investigated, and as a result, it was found that when the modulus of elasticity of the cord at 29.4 N load at 160°C was in the range of 2.0 mN / (dtex% ) or more, the improvement in the plunger durability and the handling stability of the tire became remarkable.

[0069] Here, in order to sufficiently highly-elasticize the reinforcing cord, it is preferable to apply a tension of 6.9 x 10 -2 N / tex or more to the organic fiber cord at the time of adhesive treatment. The method of highly-elasticizing the cord is not limited thereto, and other methods such as low-twisting of the cord can also be used. The adhesive treatment is constituted by dry treatment, heat treatment, standardization treatment, and the like, and is performed while appropriately adjusting the temperature and the time in addition to the tension. In the present application, the adhesive treatment can be performed in either one of single-bath treatment and double-bath treatment, but it is preferable to perform the treatment in double-bath treatment, and it is preferable to apply a tension of 6.9 x 10 -2 N / tex or more to the organic fiber cord at the time of heat treatment in double-bath treatment.

[0070] The above-described organic fiber cord preferably has a breaking strength of 6.5 cN / dtex or more, a breaking elongation of 10% or more, and a modulus of elasticity at 7% elongation of 6.0 mN / (dtex% ) or more. Here, the breaking strength, the breaking elongation, and the modulus of elasticity at 7% elongation of the organic fiber cord are values measured at room temperature (23°C). In addition, each property of the organic fiber cord can be measured in accordance with JIS L 1013 "Chemical Fiber Filament Test Method".

[0071] The modulus of elasticity at 7% elongation is calculated by converting the slope (N / %) of the tangent line at the point corresponding to 7% elongation on the load-elongation curve of the cord to a value per 1 dtex. The slope of the tangent line at the point corresponding to 7% elongation on the load-elongation curve means the slope of the tangent line S at the point corresponding to 7% elongation on the load-elongation curve C of the cord shown in Fig. 1. Figure 3 The modulus of elasticity at 7% elongation is calculated by converting the slope (N / %) of the tangent line at the point corresponding to 7% elongation on the load-elongation curve of the cord to a value per 1 dtex. The slope of the tangent line at the point corresponding to 7% elongation on the load-elongation curve means the slope of the tangent line S at the point corresponding to 7% elongation on the load-elongation curve C of the cord shown in Fig. 1.

[0072] The organic fiber cord having a cut strength of 6.5 cN / dtex or more, a cut elongation of 10% or more, and a modulus of elasticity at 7% elongation of 6.0 mN / (dtex-%) or more has high strength at the time of cutting, high elongation at the time of cutting, and high modulus of elasticity at 7% elongation, and thus can improve the plunger durability and the handling stability of the tire.

[0073] The above organic fiber cord preferably has a twist factor a represented by the following formula (3) of 500 to 2500. When the twist factor a is 500 or more, the restraint force of the filament becomes strong, and sufficient adhesion can be obtained, and when it is 2500 or less, a modulus of elasticity sufficient for obtaining an effect of improving the durability against the impact of the protrusion and an effect of suppressing the protrusion of the belt can be exerted.

[0074] a = T x d 1 / 2 …(3)

[0075] In formula (3), T is the number of twists (times / 100 mm) of the organic fiber cord, and d is the total denier (dtex) of the organic fiber cord.

[0076] In addition, the total denier of the above organic fiber cord is preferably 1000 to 3500 dtex. When the total denier of the organic fiber cord is 1000 dtex or more, a modulus of elasticity sufficient for obtaining an effect of improving the durability against the impact of the protrusion and an effect of suppressing the protrusion of the belt can be exerted, and when it is 3500 dtex or less, the cords can be densely arranged, and the stiffness per unit width can be sufficiently ensured.

[0077] Note that the green tire expands in the tire radial direction by several % at the time of vulcanization, and therefore, if the modulus of elasticity of the reinforcing cord used in the belt reinforcing layer 3 is high, the organic fiber cord as the reinforcing cord in the belt reinforcing layer 3 can directly contact the belt cord in the belt layer 2 without passing through the coated rubber at the time of vulcanization molding. Therefore, it is preferable to design the diameter of the green tire to a certain degree in advance, and to appropriately adjust the tension at the time of winding the reinforcing cord coated with the coated rubber to form the belt reinforcing layer 3, thereby sufficiently securing the distance (gauge) between the cords of the belt layer 2 and the belt reinforcing layer 3. From this perspective, the above-mentioned organic fiber cord preferably has an elongation of 2% or less of the cord length before vulcanization in the tire after vulcanization. In the case where the tire is molded with the cord elongation of 2% or less, the contact between the organic fiber cord and the belt cord can be suppressed, and the separation at the belt end portion during running can be suppressed.

[0078] The raw material of the above-mentioned organic fiber cord is not particularly limited, and can be derived from a synthetic product, can be derived from a living organism, can be derived from mechanical recycling of PET products such as plastic bottles, which are pulverized, melted, and re-spun, or can be derived from chemical recycling of PET products such as plastic bottles, which are depolymerized and re-polymerized.

[0079] In addition, the structure of the above-mentioned organic fiber cord is not particularly limited, and can be a single twist structure, or can be a twisted structure (a double twist structure, etc.). In the case of a single twist structure, for example, a twisted cord can be obtained by aligning the original yarn and twisting it in one direction. In addition, in the case of a double twist structure, for example, a twisted cord can be obtained by applying a primary twist to the original yarn, and then applying a secondary twist to the plurality of original yarns in the opposite direction.

[0080] The above-mentioned organic fiber cord, and particularly the PET cord, is preferably subjected to adhesive treatment with an adhesive composition, which is an adhesive composition containing a thermoplastic polymer (A), a thermally reactive water-based urethane resin (B), and an epoxy compound (C), or an adhesive composition containing a rubber latex (D) in addition to these (A) to (C) components, the main chain of the (A) component substantially not containing a carbon-carbon double bond having an addition reactivity, and having at least one functional group having cross-linkability as a side group. By subjecting to adhesive treatment with such an adhesive composition, the adhesion of the cord to the coated rubber at high temperatures can be improved.

[0081] In the past, as an adhesive treatment of organic fiber cords, particularly PET cords, so-called double bath treatment has been performed, in which an epoxy or isocyanate is applied to the surface of the cord, and a resin (RFL resin) obtained by mixing resorcinol, formaldehyde and latex is applied thereover. However, in such a method, the resin used in the single bath sometimes becomes very hard, the strain input to the cord increases, and the fatigue resistance of the cord decreases. In addition, such a resin can exhibit sufficient cord-rubber adhesion at ordinary temperatures, but the adhesion sometimes extremely decreases at high temperatures of 130°C or higher. In contrast, by using a single bath mixed solution in which a thermoplastic polymer (A) having at least one functional group having cross-linkability as a side group and substantially not containing a carbon-carbon double bond having addition reactivity in the main chain structure, a thermally reactive waterborne polyurethane resin (B) and an epoxy compound (C) are mixed, the cord is not cured, and the adhesion to the coated rubber can be sufficiently ensured even at high temperatures of 180°C or higher.

[0082] The main chain of the thermoplastic polymer (A) is mainly a linear structure. As the main chain, for example, an acrylic polymer, a vinyl acetate polymer, an ethylene-vinyl acetate polymer or the like, or a urethane-based high molecular polymer is preferred. Among them, the thermoplastic polymer (A) is not limited to the addition polymer and the urethane-based high molecular polymer, as long as it has a function of suppressing the resin flowability at high temperatures by cross-linking the functional group of the side group, and ensuring the breaking strength of the resin.

[0083] In addition, as the functional group of the side group of the thermoplastic polymer (A), an oxazoline group, a bismaleimide group, a (blocked) isocyanate group, an aziridine group, a carbodiimide group, a hydrazine group, an epoxy group, a cyclic sulfur group or the like is preferred.

[0084] As the monomer constituting the olefinic addition polymer, there can be mentioned an olefinically unsaturated monomer having one carbon-carbon double bond, a monomer having two or more carbon-carbon double bonds. Among these, as the olefinically unsaturated monomer having one carbon-carbon double bond, there can be mentioned α-olefins such as ethylene, propylene, butene, isobutene, etc.; α,β-unsaturated aromatic monomers such as styrene, α-methylstyrene, monochlorostyrene, vinyltoluene, vinyl naphthalene, sodium styrene sulfonate, etc.; olefinic carboxylic acids and their salts such as itaconic acid, fumaric acid, maleic acid, acrylic acid, methacrylic acid, butenetricarboxylic acid, etc.; acid anhydrides such as maleic anhydride, itaconic anhydride, etc.; esters of unsaturated carboxylic acids such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, methoxy polyethylene glycol (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-aminoethyl (meth)acrylate, etc.; monoesters of olefinic dicarboxylic acids such as itaconic acid monoethyl ester, fumaric acid monobutyl ester, maleic acid monobutyl ester, etc.; diesters of olefinic dicarboxylic acids such as itaconic acid diethyl ester, fumaric acid dibutyl ester, etc.; amides of α,β-olefinically unsaturated acids such as acrylamide, maleic acid amide, N-hydroxymethyl acrylamide, N-(2-hydroxyethyl)acrylamide, methacrylamide, N-hydroxymethyl methacrylamide, N-(2-hydroxyethyl) methacrylamide, maleic acid amide, etc.; hydroxyl group-containing monomers such as 2-hydroxyethyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, etc.; unsaturated nitriles such as acrylonitrile, methacrylonitrile, fumaronitrile, α-chloroacrylonitrile, etc.; vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, etc.; vinyl ketone; vinyl amide; halogen-containing α,β-unsaturated monomers such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, etc.; vinyl compounds such as vinyl acetate, vinyl valerate, vinyl octanoate, vinyl pyridine, etc.; addition polymerizable oxazolines such as 2-isopropenyl-2-oxazoline, etc.; heterocyclic vinyl compounds such as vinyl pyrrolidone, etc.; silane compounds containing an unsaturated bond such as vinyl ethoxy silane, α-methylacryloyloxypropyl trimethoxysilane, etc. These can be used singly or in combination of two or more. In the present application, it is preferred that the thermoplastic polymer (A) is obtained by radical addition polymerization of these monomers. Further, as the monomer constituting the main chain skeleton and having two or more carbon-carbon double bonds, there can be mentioned conjugated diene monomers such as 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, halogen-substituted butadienes such as chlorobutadiene, etc.; and non-conjugated diene monomers such as vinyl norbornene, dicyclopentadiene, 1,4-hexadiene, etc. These can be used singly or in combination of two or more.

[0085] The olefinic addition polymer contains units derived from an olefinically unsaturated monomer having 1 carbon-carbon double bond and a monomer containing 2 or more carbon-carbon double bonds, and the carbon-carbon double bond having sulfur reactivity is preferably 10 mol% or less, more preferably 0 mol%, based on the monomer composition ratio of the total amount of monomers.

[0086] The method of introducing a functional group having cross-linkability into the olefinic addition polymer to produce the thermoplastic polymer (A) is not particularly limited. For example, a method of copolymerizing an addition-polymerizable monomer having oxazoline, an addition-polymerizable monomer having an epoxy group, an addition-polymerizable monomer having maleimide, an addition-polymerizable monomer having a blocked isocyanate group, an addition-polymerizable monomer having a cyclic sulfur group, or the like, when the olefinic addition polymer is polymerized, or the like, can be employed.

[0087] In addition, the urethane-based high molecular polymer is mainly a high molecular polymer having a plurality of urethane bonds, urea bonds, or the like, produced from the reaction of isocyanate groups with active hydrogens, in the molecule, obtained by polyaddition reaction of a polyisocyanate with a compound having 2 or more active hydrogens. Note that it can also be a polymer containing not only the bonds produced from the reaction of isocyanate groups with active hydrogens, but also uretdione, carbodiimide, or the like, produced from the reaction of ester bonds, ether bonds, amide bonds, and isocyanate groups contained in the molecule of the active hydrogen compound, with each other.

[0088] As the thermal reaction type water-based polyurethane resin (B), a resin having 2 or more blocked isocyanate groups having thermal dissociation in one molecule is preferred. For example, a thermal reaction type water-based polyurethane compound represented by the following general formula (4) or the like is particularly preferred.

[0089]

[0090] In formula (4), A represents an isocyanate residue of an organic polyisocyanate compound having a functional group number of 3 to 5, Y represents an active hydrogen residue of a blocking agent compound that dissociates isocyanate groups by heat treatment, Z represents an active hydrogen residue of a compound having at least 1 active hydrogen atom and at least 1 anion-forming group in the molecule, X is an active hydrogen residue of a polyol compound having 2 to 4 hydroxyl groups and an average molecular weight of 5000 or less, n is an integer of 2 to 4, and p + m is an integer of 2 to 4 (m > 0.25).

[0091] As the epoxy compound (C), a compound containing 2 or more, preferably 4 or more, epoxy groups in one molecule is used, and a reaction product of a compound containing an epoxy group, a polyhydric alcohol, and epichlorohydrin is preferred. As specific examples of the epoxy compound, there can be mentioned a reaction product of a polyhydric alcohol such as diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, sorbitol polyglycidyl ether, and the like, and epichlorohydrin; a novolak-type epoxy resin such as phenol novolak-type epoxy resin, cresol novolak-type epoxy resin, and the like; a bisphenol A-type epoxy resin; and the like.

[0092] As the rubber latex (D), a vinylpyridine-styrene-butadiene copolymer latex, a styrene-butadiene copolymer latex, and the like are preferred, and there is no particular limitation.

[0093] In the adhesive treatment of organic fiber cords, particularly PET cords, it is preferred to use the above-mentioned three components (A), (B), and (C) as a single bath treatment liquid, and to use a conventional RFL resin as a double bath treatment liquid. Alternatively, a mixed liquid of the above-mentioned components (A), (B), (C), and (D) can be used to perform the treatment with a single bath. Note that, in terms of dry weight ratio, the (A) component is preferably 2 to 75% by dry weight of the adhesive composition, the (B) component is preferably 15 to 87% by dry weight of the adhesive composition, the (C) component is preferably 11 to 70% by dry weight of the adhesive composition, and the (D) component is preferably 20% by dry weight or less of the adhesive composition.

[0094] On the other hand, from the viewpoint of environmental protection, as the adhesive composition for organic fiber cords, it is preferred to use an impregnation treatment liquid that does not contain resorcinol and formalin. As such an impregnation treatment liquid, for example, there can be mentioned a composition containing a rubber latex having an unsaturated diene (a), and one or more compounds selected from the group consisting of a compound having a backbone structure composed of a polyether and an amine functional group, a compound having an acrylamide structure, a polypeptide, polylysine, and a carbodiimide (b). Alternatively, as such an impregnation treatment liquid, for example, there can be mentioned a composition containing one or more compounds selected from the group consisting of an aqueous compound having a (thermally dissociable blocked) isocyanate group (c), a polyhydric phenol (d), and a polyvalent metal salt (e), in addition to the above-mentioned rubber latex having an unsaturated diene (a) and the compound (b).

[0095] Further, as the impregnation treatment liquid not containing resorcinol and formalin, a composition containing the polyphenol (I) and the aldehyde (II) can also be cited. In addition, the composition can further contain at least either one of the isocyanate compound (III) and the rubber latex (IV) in addition to the polyphenol (I) and the aldehyde (II).

[0096] The adhesive composition to which the above organic fiber cord is subjected to an adhesive treatment, that is, coating, exhibits good adhesiveness even in the case where resorcinol is not used in consideration of the load on the environment by containing the polyphenol (I) and the aldehyde (II).

[0097] 〔Polyphenol (I)〕

[0098] By containing the polyphenol (I) as a resin component in the above adhesive composition, the adhesiveness to the organic fiber cord can be improved. Here, the polyphenol (I) is typically a water-soluble polyphenol, and is not particularly limited as long as it is a polyphenol other than resorcinol. In the polyphenol (I), the number of aromatic rings or the number of hydroxyl groups can be appropriately selected.

[0099] From the viewpoint of achieving more excellent adhesiveness, the above polyphenol (I) preferably has 2 or more hydroxyl groups, and more preferably has 3 or more hydroxyl groups. By causing the above polyphenol to have 3 or more hydroxyl groups, the polyphenol or the condensate of the polyphenol is dissolved in the adhesive composition (impregnation treatment liquid) containing moisture. Thereby, the polyphenol can be uniformly distributed in the adhesive composition, and thus more excellent adhesiveness can be achieved. Furthermore, in the case where the polyphenol (I) is a polyphenol containing a plurality of, that is, 2 or more aromatic rings, 2 or 3 hydroxyl groups are respectively present at the ortho position, the meta position, or the para position in these aromatic rings.

[0100] As the above polyphenol (I), for example, a substance described as a polyphenol compound in International Publication No. 2022 / 130879 can be used. These polyphenols (I) can be used alone as one kind, or can be used in combination as two or more kinds.

[0101] [Aldehyde (II)]

[0102] The above adhesive composition contains the aldehyde (II) as a resin component in addition to the above polyphenol (I), and thereby high adhesiveness can be achieved together with the above polyphenol (I). Here, the aldehyde (II) is not particularly limited, and can be appropriately selected depending on the required performance. Note that in the present specification, the aldehyde (II) also includes an aldehyde derivative in which an aldehyde is a source.

[0103] Examples of the aldehydes (II) include monoaldehydes such as formaldehyde, acetaldehyde, butyraldehyde, acrolein, propionaldehyde, chloral, butyraldehyde, hexanal, and allylaldehyde; aliphatic dialdehydes such as glyoxal, malondialdehyde, succinaldehyde, glutaraldehyde, and adipaldehyde; aldehydes having an aromatic ring; and dialdehyde starch. These aldehydes (II) may be used alone or in combination of two or more.

[0104] The aldehyde (II) is preferably an aldehyde having an aromatic ring, or contains an aldehyde having an aromatic ring. This is because it can provide better adhesion. Furthermore, the aldehyde (II) is preferably formaldehyde-free. Here, "formaldehyde-free" means, for example, that the formaldehyde content in the total mass of the aldehyde is less than 0.5% by mass.

[0105] In the above-mentioned adhesive composition, polyphenols (I) and aldehydes (II) are in a condensed state, and the mass ratio of polyphenols to aldehydes having an aromatic ring (content of aldehydes having an aromatic ring / content of polyphenols) is preferably 0.1 or more and 3 or less. This is because, in this case, the hardness and adhesion of the resin, the product of the condensation reaction between the polyphenols and the aldehydes having an aromatic ring, will be more suitable. From the same perspective, the mass ratio of polyphenols to aldehydes having an aromatic ring (content of aldehydes having an aromatic ring / content of polyphenols) in the above-mentioned adhesive composition is more preferably 0.25 or more, and more preferably 2.5 or less.

[0106] In addition, the said mass ratio is the mass of a dry thing (solid content ratio).

[0107] The total content of the polyphenols (I) and aldehydes (II) in the adhesive composition is preferably 3 to 30% by mass. This is because in this case, it is possible to ensure better adhesion without deteriorating workability, etc. From the same perspective, the total content of the polyphenols (I) and aldehydes (II) in the adhesive composition is more preferably 5% by mass or more, and more preferably 25% by mass or less.

[0108] In addition, the said total content is the mass of a dry thing (solid content ratio).

[0109] [Isocyanate compound (III)]

[0110] The adhesive composition preferably contains an isocyanate compound (III) in addition to the polyphenols (I) and aldehydes (II). In this case, the adhesive property of the adhesive composition can be further improved through a synergistic effect with the polyphenols (I) and aldehydes (II).

[0111] Here, the isocyanate compound (III) is a compound having an action of promoting adhesion to a resin material of an adherend as the adhesive composition, such as a phenol / aldehyde resin formed by condensation of the polyphenol (I) and the aldehyde (II), and has an isocyanate group as a polar functional group. These isocyanate compounds (III) can be used alone as one kind or in combination with two or more kinds.

[0112] The above isocyanate compound (III) is not particularly limited, and an aromatic compound containing a (blocked) isocyanate group is preferable from the viewpoint of further improving adhesion. By including the aromatic compound containing a (blocked) isocyanate group in the above adhesive composition, the aromatic compound containing a (blocked) isocyanate group is distributed in a position near the interface between the organic fiber cord and the adhesive composition, and as a result, a further adhesion-promoting effect is obtained, and by this effect, the adhesion of the adhesive composition to the organic fiber cord can be further highly improved.

[0113] As the above aromatic compound containing a (blocked) isocyanate group, the compound described in Japanese Patent Application No. 2023-040157, the compound described in Japanese Patent Application No. 2023-030762 can be used.

[0114] The content of the isocyanate compound (III) in the above adhesive composition is not particularly limited, and is preferably 5 to 65% by mass from the viewpoint of more surely ensuring excellent adhesion. From the same viewpoint, the content of the isocyanate compound (III) in the above adhesive composition is more preferably 10% by mass or more, and further more preferably 45% by mass or less.

[0115] Note that the above content is the mass of the dried substance (solid content ratio).

[0116] [Rubber latex (IV)]

[0117] The above adhesive composition can substantially contain a rubber latex (IV) in addition to the above polyphenol (I), aldehyde (II), and isocyanate compound (III). By this, the adhesive composition can further improve adhesion to a rubber member.

[0118] Here, as the rubber latex (IV), there is no particular limitation, and in addition to natural rubber (NR), synthetic rubbers such as polyisoprene rubber (IR), styrene-butadiene copolymer rubber (SBR), polybutadiene rubber (BR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), halogenated butyl rubber, acrylonitrile-butadiene rubber (NBR), or vinylpyridine-styrene-butadiene copolymer rubber (Vp) can be listed. These rubber latexes (IV) can be used alone as one kind or in combination with two or more kinds.

[0119] When preparing an adhesive composition containing the rubber latex (IV), it is preferred to mix the rubber latex (IV) with the phenol (I) and the aldehyde (II) before adding the isocyanate compound (III).

[0120] The content of the rubber latex (IV) in the adhesive composition is preferably 20% by mass or more, more preferably 25% by mass or more, and is preferably 70% by mass or less, more preferably 60% by mass or less.

[0121] It should be noted that the method for producing the adhesive composition is not particularly limited. Examples include a method of mixing and aging raw materials such as polyphenols (I), aldehydes (II), and rubber latex (IV); or a method of mixing and aging the polyphenols (I) and aldehydes (II), followed by adding and aging the rubber latex (IV). If the raw materials include an isocyanate compound (III), the adhesive composition may also be produced by adding the rubber latex (IV) and aging the mixture, followed by adding the isocyanate compound (III).

[0122] The belt reinforcement layer 3 is preferably formed by treating the organic fiber cords with an adhesive, covering them with a coating rubber to form a narrow strip, and then continuously winding the strip in a spiral shape on the belt layer 2 in the tire circumferential direction.

[0123] exist Figure 1 In the example shown, the belt reinforcement layer 3 includes a so-called cover layer 3A, which is arranged on the outer side of the belt layer 2 in the tire radial direction so as to cover the entire belt layer 2 in the tire width direction, and a so-called layered layer 3B, which is arranged in a pair so as to cover only the opposite ends of the belt layer 2 in the tire width direction. However, this structure is not limited to this. For example, the belt reinforcement layer 3 may consist of only a single cover layer 3A, a single pair of layered layers 3B, or a combination of one, two, or more cover layers 3A and one, or more, pairs of layered layers 3B.

[0124] In the illustrated tire 10, the carcass 1 is composed of a single carcass ply. The carcass ply is a component that forms the tire skeleton and is arranged in at least one ply, for example, one to three plies. In the illustrated tire 10, bead cores 4 are embedded in a pair of bead portions 13, and the carcass ply 1 is folded back around the bead cores 4 from the inside to the outside of the tire and secured thereto. However, the securing method of the carcass ply 1 is not limited thereto. As reinforcing cords for the carcass ply 1, for example, polyesters such as polyethylene naphthalate (PEN) and polyethylene terephthalate (PET), nylon, and organic fiber cords such as semi-aromatic fibers can be used.

[0125] In the illustrated tire 10, a belt layer 2 consisting of two belts 2a and 2b with their cord directions inclined relative to the tire circumferential direction is disposed radially outward of the carcass 1. The belt layer 2 is provided in at least one layer, for example, two to four layers. When two or more layers are provided, the belt layer 2 is arranged so that the directions of the reinforcing cords alternate at least partially between the layers. In addition to steel cords, organic fiber cords can also be used as the reinforcing cords of the belt layer 2.

[0126] Although not shown, in the tire of the present invention, a bead filler having a tapered cross-section can be disposed radially outwardly of the bead core 4, and an inner liner composed of a rubber or resin material can typically be disposed in the innermost layer of the tire. The tire of the present invention is preferably a pneumatic tire, and the gas filling the tire may be, in addition to normal air or air with an adjusted oxygen partial pressure, an inert gas such as nitrogen, argon, or helium.

[0127] Example

[0128] Hereinafter, the present invention will be described in more detail using specific examples.

[0129] [Example 1]

[0130] Production with Figure 1 The structure shown is a 195 / 65R15 passenger car tire. This tire has a carcass composed of a single carcass ply as its framework. In the tread portion, on the radially outer side of the carcass, there are, in this order: two belt layers (made of steel), arranged with their cords interlaced at angles of ±66 degrees relative to the tire equatorial plane; an overlay layer arranged to cover the entire belt layer in the tire width direction; and two belt reinforcement layers arranged in a pair to cover both ends of the belt layer in the tire width direction.

[0131] The belt reinforcement layer is formed by coating reinforcement cords aligned with the tire's circumferential direction with a coating rubber. The formulation of the rubber composition used in the coating rubber of the belt reinforcement layer is shown in Table 1 below, and the conditions of the reinforcement cords and coating rubber in the belt reinforcement layer are shown in Table 2 below.

[0132] Passenger car tires of Reference Example, Comparative Examples 1 and 2, and Examples 2 and 3 were prepared in the same manner as in Example 1 except that the conditions of the reinforcing cords and coating rubber in the belt reinforcement layer were changed as shown in Table 2 below.

[0133] [Table 1]

[0134]

[0135] *1)NR: Natural rubber, TSR#20

[0136] *2) SBR (1): Butadiene-styrene rubber, solution polymerized SBR, non-extended (JSR 1500)

[0137] *3) SBR (2): Butadiene-styrene rubber, emulsion polymerized SBR, 27.3% extended (JSR 1778)

[0138] *4) CB (1): GPF grade carbon black, N2SA (nitrogen adsorption specific surface area) 28 m 2 / g, DBP absorption 89 ml / 100 g

[0139] *5) CB (2): HAF grade carbon black, N2SA (nitrogen adsorption specific surface area) 71 m 2 / g, DBP absorption 103 ml / 100 g

[0140] *6) Zinc oxide: Zinc oxide 3 kinds manufactured by HAKUSUI TECH Co., Ltd.

[0141] *7) Antioxidant: NONFLEX RD manufactured by Seiko Chemical Co., Ltd.

[0142] *8) Sulfur: SULFUR (5% OIL-TREATED) manufactured by TANAKA BLUE CO., LTD.

[0143] *9) Curing accelerator: Sanceler (SANCELER) NS-G, Sanceler (SANCELER) DM-TG

[0144] For each of the obtained test tires, evaluation of the rolling resistance and the passing noise was performed in accordance with the following. These results are collectively shown in Table 2 below.

[0145] (Evaluation of the rolling resistance)

[0146] The rolling resistance of each of the test tires was measured using a rolling resistance tester in accordance with SAE J 1269. The results were expressed as an index with the reference example being 100. The smaller the value, the lower the rolling resistance, and the better the result.

[0147] (Evaluation of the passing noise)

[0148] The passing noise (dB) of each of the test tires was measured in accordance with the international standard (ECER117). The results were expressed as an index with the reference example being 100. The smaller the value, the lower the passing noise, and the better the result.

[0149] [Table 2]

[0150]

[0151] *10) is the diameter D (mm) of the circumscribed circle of the reinforcing cord.

[0152] *11) is a value of cord stiffness sc (mN / (dtex-%)) of the reinforcing cord of the belt reinforcing layer measured under conditions of temperature 24°C and humidity 55%.

[0153] *12) is the arrangement density N (root / 100 mm) of the reinforcing cord of the belt reinforcing layer.

[0154] *13) is a value of the circumferential stiffness S per 100 mm unit width of the belt reinforcing layer defined by the following formula (1).

[0155] S = sc x N (1)

[0156] (In the formula, sc is the cord stiffness (mN / (dtex-%)) of the reinforcing cord of the belt reinforcing layer measured under conditions of temperature 24°C and humidity 55%, and N is the arrangement density (root / 100 mm) of the reinforcing cord of the belt reinforcing layer.)

[0157] *14) is a value of the storage modulus E'(24°C) (MPa) of the coated rubber measured under conditions of temperature 24°C, amplitude ±1%, and frequency 52 Hz.

[0158] *15) is a value of the loss tangent tan δ (24°C) measured under conditions of temperature 24°C, initial strain 6%, amplitude ±1%, and frequency 52 Hz.

[0159] *16) is a value of the loss tangent tan δ (60°C) measured under conditions of temperature 60°C, initial strain 1.5%, amplitude ±1%, and frequency 52 Hz.

[0160] *17) is a cross-sectional area (mm 2 ) of the coated rubber contained in the belt reinforcing layer per 100 mm unit width.

[0161] *18) is a value of the loss index L of the coated rubber contained in the belt reinforcing layer per 100 mm unit width defined by the following formula (2).

[0162] L = tan δ x ((100 x D) - π(D / 2) 2 x N) (2)

[0163] (In the formula, tan δ is a value of the loss tangent of the coated rubber measured under conditions of temperature 24°C, initial strain 6%, amplitude ±1%, and frequency 52 Hz, D is a diameter (mm) of a circumscribed circle of the reinforcing cord, and N is the arrangement density (root / 100 mm) of the reinforcing cord in the belt reinforcing layer.)

[0164] From the above results, it is clear that the test tire according to each of the embodiments can suppress the deterioration of the passing noise during running even when the PET cord higher in elasticity than nylon is used to reduce the rolling resistance.

[0165] Legend of reference signs

[0166] 1 carcass

[0167] 2 belt layer

[0168] 2a, 2b belt

[0169] 3 belt reinforcing layer

[0170] 3A cover layer

[0171] 3B layered layer

[0172] 4 bead core

[0173] 10 tire

[0174] 11 tread portion

[0175] 12 sidewall portion

[0176] 13 bead portion

[0177] 31 reinforcing cord

[0178] 32 coated rubber

Claims

1. A tire, characterized in that: The tire has at least one belt layer in the tread portion and at least one belt reinforcement layer arranged on the outer side of the belt layer in the tire radial direction. The belt reinforcement layer is formed by using rubber-coated reinforcing cords, the reinforcing cords are aligned so that the cord direction is substantially the circumferential direction of the tire, the circumferential stiffness S of the belt reinforcement layer per 100 mm unit width defined by the following formula (1) is 250 or more and 400 or less, and the storage modulus E' of the coating rubber measured under the conditions of a temperature of 24° C., an amplitude of ±1%, and a frequency of 52 Hz is 6.0 MPa or less, S=sc×N (1) In formula (1), sc is the cord stiffness of the reinforcing cords of the belt reinforcement layer under the conditions of temperature 24°C and humidity 55% (mN / (dtex·%)), and N is the arrangement density of the reinforcing cords of the belt reinforcement layer (cords / 100 mm).

2. The tire according to claim 1, wherein The loss index L of the coating rubber contained per unit width of 100 mm of the belt reinforcing layer, as defined by the following formula (2), is 4.00 or less. L=tanδ×((100×D)-π(D / 2) 2 ×N) (2) In formula (2), tanδ is the value of the loss tangent of the coated rubber measured under the conditions of temperature 24°C, initial strain 6%, amplitude ±1%, and frequency 52 Hz, D is the diameter of the circumscribed circle of the reinforcing cord (mm), and N is the arrangement density of the reinforcing cord in the belt reinforcement layer (roots / 100 mm).

3. The tire according to claim 1, wherein The rubber composition used in the coating rubber contains natural rubber and styrene-butadiene rubber as rubber components, and contains 70 parts by mass or more of natural rubber in 100 parts by mass of the rubber component.

4. The tire according to claim 3, wherein: The styrene-butadiene rubber is non-oil-extended.

5. The tire according to claim 1, wherein The rubber composition used in the coating rubber contains 30 to 60 parts by mass of carbon black relative to 100 parts by mass of the rubber component, and the nitrogen adsorption specific surface area (N2SA) of the carbon black is 40 m 2 / g or less.

6. The tire according to claim 1, wherein The rubber composition used in the coating rubber does not contain oil derived from a polymer.

7. The tire according to claim 1, wherein: The oil content in the rubber composition used in the coating rubber is 0.2% by mass or less.

8. The tire according to claim 1, wherein The reinforcing cords are composed of polyethylene terephthalate fibers.

Images