Pneumatic tire

Abstract

Provided is a pneumatic tire that ensures sufficient handling stability even when a vehicle is driven at high speed on a wet road. The pneumatic tire has a tread portion formed of a rubber composition containing a rubber component of styrene-butadiene rubber and isoprene-based rubber; and a resin component, wherein when Q (mass parts) is the content of the resin component with respect to 100 mass parts of the rubber component, the tire is mounted on a standard rim, the internal pressure is 250 kPa, Wt (mm) is the cross-sectional width of the tire, and Dt (mm) is the outside diameter, the content Q (mass parts) of the resin component with respect to 100 mass parts of the rubber component exceeds 25 mass parts, and Formulas 1 and 2 are satisfied.1600≦(Dt 2 ×π / 4) / Wt≦2827.4···Formula 1Q / Wt>0.1···Formula 2

Description

Technical Field

[0001] This invention relates to a pneumatic tire. Background Technology

[0002] In recent years, from the perspective of increasing attention to environmental issues and economic benefits, the requirements for automobile fuel efficiency have been increasing. Moreover, for pneumatic tires installed on automobiles (hereinafter referred to as "tires"), it is necessary to improve fuel efficiency.

[0003] Conventionally, as a specific means of improving tire fuel efficiency, tire compound containing modified synthetic rubber is typically used to form the tread portion. In this modified synthetic rubber, end-modified polymers are applied to the synthetic rubber, and the number of ends is increased by reducing the molecular weight of the polymer to improve the modification effect.

[0004] However, in such tire blends, the polymers contained in the blend have low molecular weights, which may reduce the breaking strength and wear resistance of the finished tires.

[0005] Therefore, it has been proposed to add isoprene rubber with excellent fracture strength to the above-mentioned modified synthetic rubber to form the tread portion, thereby improving fracture strength and wear resistance while maintaining fuel efficiency (low rolling resistance) (e.g., Patent Documents 1 to 4).

[0006] [Existing Technical Documents]

[0007] [Patent Literature]

[0008] [Patent Document 1] JP 2014-213836 A

[0009] [Patent Document 2] JP 2017-52329A

[0010] [Patent Document 3] JP 2018-154181 A

[0011] [Patent Document 4] JP 2019-85445A Summary of the Invention

[0012] [The problem to be solved by the present invention].

[0013] However, tires based on these conventional technologies have reduced grip on the road surface, which may lead to poorer handling stability, especially when driving at high speeds on wet roads, and requires further improvement.

[0014] Therefore, one objective of the present invention is to provide a pneumatic tire that ensures sufficient handling stability even when traveling at high speeds on wet surfaces.

[0015] [Problem-solving methods]

[0016] The inventors have diligently researched solutions to the above-mentioned problems and discovered that these problems can be solved through the disclosure described below, and thus completed this invention.

[0017] This invention is a pneumatic tire, wherein

[0018] The tread portion is formed of a rubber composition containing styrene-butadiene rubber and isoprene rubber as rubber components, as well as resin components.

[0019] Relative to 100 parts by weight of the rubber component, the content Q (parts by weight) of the resin component exceeds 25 parts by weight, and

[0020] Satisfy the following equations 1 and 2:

[0021] 1600≦(Dt 2 (×π / 4) / Wt≦2827.4···Equation 1

[0022] Q / Wt>0.1···Equation 2,

[0023] Wherein, relative to 100 parts by mass of the rubber component, the content of the resin component is Q (parts by mass), and when the tire is mounted on a standardized rim and the internal pressure is 250 kPa, the cross-sectional width of the tire is Wt (mm), and the outer diameter of the tire is Dt (mm).

[0024] [Invention Effects]

[0025] According to the present invention, a pneumatic tire can be provided that ensures sufficient handling stability even when traveling at high speeds on wet surfaces. Detailed Implementation

[0026] The present invention will now be described in detail according to the embodiments.

[0027] [1] Features of the tire of the present invention

[0028] First, the features of the tire of the present invention will be described.

[0029] The inventors believed that conventional techniques for controlling the physical properties of rubber through blending were insufficient to provide a pneumatic tire that ensured adequate handling stability even at high speeds on wet surfaces. Furthermore, in addition to studying the physical properties of the rubber composition forming the tread portion (hereinafter also referred to as the "tread rubber composition"), it was necessary to study the tire's shape. As a result of various experiments and studies, the inventors have completed this invention.

[0030] First, in the tire of the present invention, the tire shape is such that the area of ​​the tire when viewed from the side is relatively large within a specified range relative to the cross-sectional width of the tire. This reduces repeated deformation per unit time, thus increasing the time available for heat exchange, thereby improving the heat release performance of the side portion and exhibiting sufficient fuel efficiency.

[0031] Specifically, if the tire shape satisfies 1600≦(Dt) 2 ×π / 4) / Wt≦2827.4, where when the tire is mounted on a standard rim and the internal pressure is 250 kPa, the tire's cross-sectional width is Wt (mm), and the outer diameter is Dt (mm). Appropriately ensure that the tire's area (mm²) viewed from the side is relative to the cross-sectional width Wt (mm). 2 ), that is, [(Dt / 2) 2 ×π)=(Dt 2 [×π / 4)], and improves the heat release performance of the side portion, thereby significantly reducing rolling resistance and achieving fuel efficiency. (Dt) 2 ×π / 4) / Wt is more preferably 1700 or above, even more preferably 1865 or above, even more preferably 1963.4 or above, even more preferably 1979 or above, even more preferably 1981 or above, even more preferably 2018 or above, even more preferably 2480 or above.

[0032] In the above description, "standardized rim" refers to a rim defined for each tire within a standard system, including the standard upon which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Association), it is a standardized rim of the applicable size described in the "JATMA YEAR BOOK"; in the case of ETRTO (European Tire and Rim Technology Organization), it is a "measuring rim" described in the "STANDARDS MANUAL"; and in the case of TRA (Tire and Rim Association), it is a "design rim" described in the "YEAR BOOK". For tires not specified in the standard, it refers to a rim that can be assembled and maintain internal pressure, that is, a rim that will not cause air leakage between the rim and the tire, and has the smallest rim diameter, followed by the narrowest rim width.

[0033] Furthermore, the tire's outer diameter Dt refers to the outer diameter of a tire mounted on a standardized rim with an internal pressure of 250 kPa and under no-load conditions. The tire's section width Wt (mm) refers to the width of a tire mounted on a standardized rim with an internal pressure of 250 kPa and under no-load conditions, and is calculated by excluding the sidewall patterns, text, etc., from the straight-line distance between all sidewalls (the total tire width).

[0034] However, when manufacturing tires with the aforementioned shape, the centrifugal force increases during rolling, and the tire radius also increases during rolling. Therefore, it is believed that uneven ground contact pressure may occur when driving at high speeds on wet surfaces, leading to decreased handling stability. In particular, it is thought that the wider the tire's cross-sectional width Wt, the greater the difference between the contact pressure at the center of the tread and the contact pressure at the shoulder, which often results in poorer handling stability.

[0035] To address this problem, the inventors devised a rubber composition containing isoprene rubber with excellent tensile strength as the rubber component and a large amount of resin component. In other words, as the amount of resin component increases with the cross-sectional width Wt, the resin component is sufficiently distributed even on the surface of the tire shoulder where ground contact pressure is often low. Furthermore, even at high speeds, the adhesiveness of the resin component ensures good grip on the road surface, thereby improving handling stability.

[0036] Specifically, when the content of resin component relative to 100 parts by mass of rubber component is Q (parts by mass), and when Q is greater than 1, i.e. the content of resin component exceeds 1 / 4, and the ratio of Q (parts by mass) to section width Wt (mm) (Q / Wt) exceeds 0.1, a pneumatic tire with sufficiently improved handling stability can be provided.

[0037] Furthermore, from the perspective of ensuring sufficient grip on the road surface due to the adhesiveness of the resin components, Q (parts by mass) is preferably 26 parts by mass or more, more preferably 30 parts by mass or more, even more preferably more than 30 parts by mass, even more preferably 40 parts by mass or more, even more preferably more than 40 parts by mass, and even more preferably 50 parts by mass or more. In addition, (Q / Wt) is preferably 0.12 or more, more preferably 0.15 or more, even more preferably more than 0.15, even more preferably 0.17 or more, even more preferably 0.20 or more, even more preferably more than 0.20, even more preferably 0.24 or more, and even more preferably 0.26 or more. On the other hand, it is preferably less than 0.35.

[0038] [2] A more preferred embodiment of the tire of the present invention

[0039] The tire of the present invention can achieve greater effects by adopting the following embodiments.

[0040] 1. Flatness

[0041] The tire of the present invention is preferably a tire with an aspect ratio of 40% or more, thereby increasing the height of the sidewall portion of the tire, which can suppress local deformation of the tire and further enhance the durability of the tire.

[0042] When the internal pressure is 250 kPa, the aforementioned aspect ratio (%) can be obtained using the tire section height Ht (mm) (the distance from the bottom of the bead portion to the outermost surface of the tread, i.e., 1 / 2 of the difference between the tire outer diameter and the nominal rim diameter) and the tire section width Wt (mm) by the following formula.

[0043] (Ht / Wt)×100(%)

[0044] The flatness ratio is more preferably 45% or more, further preferably 47.5% or more, further preferably 50% or more, further preferably 52.5% or more, further preferably 55% or more, further preferably 58% or more, and further preferably 70% or more. There is no specific upper limit, but for example, it is 100% or less.

[0045] 2. Tire shape

[0046] In the tire of the present invention, when the tire is mounted on a standardized rim and the internal pressure is 250 kPa, the specific outer diameter Dt (mm) is preferably, for example, 515 mm or more, more preferably 558 mm or more, further preferably 585 mm or more, particularly preferably 658 mm or more, and most preferably 673 mm or more. On the other hand, it is preferably less than 843 mm, more preferably less than 802 mm, further preferably less than 725 mm, further preferably less than 719 mm, further preferably less than 707 mm, further preferably less than 700 mm, and particularly preferably less than 685 mm.

[0047] The specific cross-sectional width Wt (mm) is preferably 115 mm or more, more preferably 130 mm or more, even more preferably 150 mm or more, even more preferably 155 mm or more, even more preferably 170 mm or more, particularly preferably 185 mm, and most preferably 193 mm or more. On the other hand, it is preferably less than 305 mm, more preferably less than 255 mm, even more preferably less than 245 mm, even more preferably less than 210 mm, even more preferably less than 205 mm, particularly preferably less than 205 mm, and most preferably less than 200 mm.

[0048] The specific cross-sectional height Ht (mm) is preferably 37 mm or more, more preferably 87 mm or more, and even more preferably 95 mm or more. On the other hand, it is preferably less than 180 mm, more preferably less than 147 mm, even more preferably less than 144 mm, even more preferably less than 112 mm, even more preferably less than 109 mm, and even more preferably less than 101 mm.

[0049] In this invention, considering the stability of ride comfort during driving, (Dt-2×Ht) is preferably 430 (mm) or more, more preferably 432 (mm) or more, even more preferably 450 (mm) or more, even more preferably 470 (mm) or more, even more preferably 480 (mm) or more, and even more preferably 483 (mm) or more. On the other hand, considering the deformation of the tread portion, it is preferably less than 560 (mm), more preferably less than 530 (mm), even more preferably less than 510 (mm), and even more preferably less than 508 (mm).

[0050] In addition, the imaginary volume V (mm) of the tire 3 The tire's dimensions, which are the spaces it occupies when mounted on a standardized rim and with an internal pressure of 250 kPa, can be calculated using the following formula based on the tire's cross-sectional width Wt (mm), outer diameter Dt (mm), and cross-sectional height Ht (mm):

[0051] V = [(Dt / 2)] 2 -{(Dt / 2)-Ht} 2 ]×π×Wt.

[0052] The specific hypothetical volume V is preferably 13,000,000 mm². 3 The above, preferably 29,000,000 mm 3 The above further optimizes the thickness to 31,230,020mm. 3 The above, and further preferred, is 36,000,000 mm. 3 That's all. On the other hand, it is preferably less than 88,000,000 mm. 3 More preferably 77,134,503 mm 3 Below, a further preferred size is less than 66,000,000 mm. 3 Further optimization of 53,167,961 mm 3 Hereinafter, a further preferred size is less than 44,000,000 mm. 3 Furthermore, a diameter of less than 38,800,000 mm is particularly preferred. 3 .

[0053] Furthermore, in this invention, the hypothetical volume V (mm²) of the tire is preferred. 3 The cross-sectional width Wt (mm) and the cross-sectional width satisfy [(V+1.5×10) 7 ) / Wt]≦4.02×10 5 [(V+1.5×10] 7 ) / Wt]More preferably 3.62×10 5 The following is a further preferred option: 3.33×10 5 Below, and further preferred is 2.99×105 the following.

[0054] In this way, by reducing the imaginary volume V of the tire based on the reduction of the tire cross-sectional width Wt, and by reducing the volume of the tire itself, the rate of outer diameter growth due to centrifugal force can be reduced. Therefore, it is believed that the deformation of the bead portion can be reduced, and the rounding of the tread portion can also be suppressed.

[0055] More preferably, [(V+2.0×10] 7 ) / Wt]≦4.02×10 5 A further preferred option is [(V+2.5×10 7 ) / Wt]≦4.02×10 5 .

[0056] In addition, [(V+2.0×10 7 ) / Wt] Preferably 3.81×10 5 Below, 3.57×10 is preferred. 5 Below, and further preferred is 3.31×10 5 Below. And [(V+2.5×10 7 ) / Wt] Preferably 4.01×10 5 Below, 3.82×10 is preferred. 5 Below, and further preferred is 3.63×10 5 the following.

[0057] [3] Embodiments of the present invention

[0058] The present invention will now be described in detail according to the embodiments.

[0059] 1. Tread rubber composition

[0060] In this embodiment, the tread rubber composition may be obtained from the rubber components, resin components and other blended materials described below.

[0061] (1) Rubber composition

[0062] In this embodiment, as described above, the tread rubber composition contains SBR and isoprene rubber as rubber components. In 100 parts by weight of the rubber component, the content of SBR and isoprene rubber as a whole is preferably 60 parts by weight or more. Specifically, the content of SBR is preferably greater than 50 parts by weight and less than 80 parts by weight.

[0063] (a) Styrene-butadiene rubber (SBR)

[0064] As a styrene-butadiene rubber, SBR with a weight-average molecular weight of, for example, 100,000 or more and 2,000,000 or less is preferred. Therefore, the strain and stress strength of the SBR phase can be improved, thereby further enhancing the breaking strength of the tire.

[0065] The styrene content (hereinafter also referred to as "styrene amount") in the SBR used in this embodiment is preferably 5% by mass or more and 25% by mass or less. The styrene content in the rubber composition is preferably 1% by mass or more and 5% by mass or less. Therefore, the aggregation of styrene in the rubber composition can be suppressed, thereby improving the tread's responsiveness. The amount of vinyl bonds in the butadiene portion of the SBR (the amount of 1,2-bonded butadiene units) is preferably 40% by mass or less. Then, the structural identification of the SBR (measuring the amount of styrene and the amount of vinyl bonds) can be performed using, for example, a JNM-ECA series instrument manufactured by JEOL Ltd.

[0066] There are no particular limitations on SBR; for example, emulsion-polymerized styrene-butadiene rubber (E-SBR) and solution-polymerized styrene-butadiene rubber (S-SBR) can be used. SBR can be unmodified or modified, but when modified S-SBR is used, dispersibility is improved, and abrasion resistance and anti-slip properties are expected to be further enhanced. Therefore, it is preferred.

[0067] Modified SBR can be any SBR with functional groups that interact with fillers (such as silica). Examples include:

[0068] Terminal modified SBR (terminal modified SBR with the above-mentioned functional groups at the end), wherein at least one end of the SBR is modified by a compound (modifier) ​​having the above-mentioned functional groups.

[0069] The SBR is modified on the main chain, and its functional groups are on the main chain.

[0070] A main-chain terminal modified SBR having functional groups in both the main chain and the terminal (e.g., a main-chain terminal modified SBR having the aforementioned functional groups and at least one terminal modified with the aforementioned modifier); and

[0071] Terminally modified SBRs are modified (coupled) by using polyfunctional compounds with two or more epoxy groups in the molecule, and introducing epoxy or hydroxyl groups therein.

[0072] Examples of functional groups include amino, amide, silyl, alkoxysilyl, isocyanate, imino, imidazo, urea, ether, carbonyl, oxycarbonyl, mercapto, thioether, dithioether, sulfonyl, sulfinyl, thiocarbonyl, ammonium, imide, hydrazine, azo, diazo, carboxyl, nitrile, pyridinyl, alkoxy, hydroxyl, oxygen, and epoxy. Furthermore, these functional groups may also have substituents.

[0073] Furthermore, as a modified SBR, for example, an SBR modified with a compound (modifier) ​​represented by the following formula can be used.

[0074] [Chemistry 1]

[0075]

[0076] In the formula, R 1 R 2 and R 3 They are the same or different, and represent alkyl, alkoxy, siloxy, acetal, carboxyl (-COOH), mercapto (-SH) or their derivatives. R 4 and R 5 They are the same or different, and represent hydrogen atoms or alkyl groups. R 4 and R 5 They can be combined to form ring structures containing nitrogen atoms. n represents an integer.

[0077] As a modified SBR modified by the compound (modifier) ​​represented by the above formula, the SBR whose polymerization end (active end) of solution-polymerized styrene-butadiene rubber (S-SBR) is modified by the compound represented by the above formula (e.g., the modified SBR described in JP-A-2010-111753).

[0078] As R 1 R 2 and R 3 Alkoxy groups are suitable (preferably alkoxy groups having 1 to 8 carbon atoms, more preferably alkoxy groups having 1 to 4 carbon atoms). As R 4 and R 5 Alkyl groups (preferably alkyl groups having 1 to 3 carbon atoms) are suitable. n is preferably 1 to 5, more preferably 2 to 4, and even more preferably 3. Furthermore, when R... 4 and R 5 When combined with nitrogen atoms to form a cyclic structure, a 4- to 8-membered ring is preferred. Alkoxy groups also include cycloalkoxy groups (such as cyclohexyloxy) and aryloxy groups (such as phenoxy and benzyloxy).

[0079] Specific examples of the aforementioned modifiers include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, and 3-diethylaminopropyltriethoxysilane. These can be used alone or in combination of two or more.

[0080] In addition, modified SBRs can also be used as modified SBRs by the following compounds (modifiers). Examples of modifiers include:

[0081] Polyhydric alcohol polyglycidyl ethers, such as ethylene glycol diglycidyl ether, glycerol triglycidyl ether, trimethylolethane triglycidyl ether and trimethylolpropane triglycidyl ether;

[0082] Polyglycidyl ethers of aromatic compounds having two or more phenolic groups, such as bisphenol A diglycidyl ether;

[0083] Polyepoxides, such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene and polyepoxide liquid polybutadiene;

[0084] Tertiary amines containing epoxy groups, such as 4,4'-diglycidyl-diphenylmethylamine and 4,4'-diglycidyl-dibenzylmethylamine;

[0085] Diglycidyl amino compounds, such as diglycidyl aniline, N,N'-diglycidyl-4-glycidyloxyaniline, diglycidyl n-toluene, tetraglycidyl m-xylylmethylamine, tetraglycidyl amino diphenylmethane, tetraglycidyl p-phenylenediamine, diglycidyl amino methylcyclohexane, and tetraglycidyl-1,3-diaminomethylcyclohexane;

[0086] Acidic chlorides containing amino groups, such as bis(1-methylpropyl)carbamate chloride, 4-morpholine carbamate chloride, 1-pyrrolidine carbamate chloride, N,N-dimethylcarbamate chloride and N,N-diethylcarbamate chloride;

[0087] Silane compounds containing epoxy groups, such as 1,3-bis(glycidylpropyl)-tetramethyldisiloxane and (3-glycidylpropyl)-pentamethyldisiloxane;

[0088] Silane compounds containing thioether groups, such as (trimethylsilyl)[3-(trimethoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(triethoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(tripropoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(tributoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(methyldimethoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(methyldiethoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(methyldipropoxysilyl)propyl] sulfide, and (trimethylsilyl)[3-(methyldibutoxysilyl)propyl] sulfide;

[0089] N-substituted aziridine compounds, such as ethyleneimine and propyleneimine;

[0090] Alkoxysilanes, such as methyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane and N,N-bis(trimethylsilyl)aminoethyltriethoxysilane;

[0091] (Thio)benzophenone compounds having an amino group and / or a substituted amino group, such as 4-N,N-dimethylaminobenzophenone, 4-N,N-di-tert-butylaminobenzophenone, 4-N,N-diphenylaminobenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(diphenylamino)benzophenone and N,N,N',N'-bis(tetraethylamino)benzophenone;

[0092] Benzaldehyde compounds having an amino group and / or a substituted amino group, such as 4-N,N-dimethylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde and 4-N,N-divinylaminobenzaldehyde;

[0093] N-substituted pyrrolidones, such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, N-tert-butyl-2-pyrrolidone and N-methyl-5-methyl-2-pyrrolidone;

[0094] N-substituted piperidinones, such as N-methyl-2-piperidinone, N-vinyl-2-piperidinone and N-phenyl-2-piperidinone;

[0095] N-substituted lactams, such as N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-laurolactam, N-vinyl-ω-laurolactam, N-methyl-β-propiolactam and N-phenyl-β-propiolactam; and

[0096] N,N-bis(2,3-epoxypropyl)-aniline, 4,4-methylenebis(N,N-glycidylaniline), tris(2,3-epoxypropyl)-1,3,5-triazine-2,4,6-trione, N,N-diethylacetamide, N-methylmaleimide, N,N-diethylurea, 1,3-dimethylvinylurea, 1,3-divinylvinylurea, 1,3-diethyl-2-imidazolium ketone, 1-methyl-3-ethyl-2-imidazolium ketone, 4-N,N-dimethylaminoacetophenone, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-propanone, and 1,7-bis(methylethylamino)-4-heptanone. Modification using the above compounds (modifiers) can be carried out by known methods.

[0097] As SBRs, SBRs produced and sold by companies such as Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Co., Ltd., Zeon Co., Ltd., and Versalis Co., Ltd. can be used. SBRs can be used alone or in combination of two or more types. When two or more types of SBRs are used in combination, the weight average of each SBR is used for the styrene content and vinyl bond content mentioned above.

[0098] (b) Isoprene rubbers

[0099] Examples of isoprene rubbers include natural rubber (NR), isoprene rubber (IR), reconstituted NR, modified NR, and modified IR. Among these, NR is preferred.

[0100] Specific types of natural rubber (NR) include, for example, SIR20, RSS#3, and TSR20, commonly used in the tire industry. There are no particular restrictions on natural rubber (IR); for example, IR2200, manufactured by Nippon Zeon Co., Ltd., commonly used in the tire industry, can be used. Modified NRs include deproteinized natural rubber (DPNR) and high-purity natural rubber (UPNR). Modified NRs also include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Modified IRs include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These can be used individually or in combination of two or more.

[0101] (c) Butadiene rubber

[0102] The tread rubber composition may further contain butadiene rubber (BR) as a rubber component, and when BR is present, the BR content in 100 parts by weight of the rubber component is, for example, 40 parts by weight or less. The weight-average molecular weight of BR is, for example, 100,000 or more and 2,000,000 or less. The vinyl bond content of BR is, for example, 1% by weight or more and 30% by weight or less. The cis content of BR is, for example, 1% by weight or more and 98% by weight or less. The trans content of BR is, for example, 1% by weight or more and 60% by weight or less.

[0103] There are no particular limitations on BR (butadiene ester) materials; BR with high cis content (cis content above 90%), BR with low cis content, and BR containing syndiotactic polybutadiene crystals can all be used. BR can be unmodified or modified; examples of modified BR include those with the aforementioned functional groups introduced. These can be used alone or in combination. The cis content can be measured using infrared absorption spectroscopy.

[0104] As a business partner (BR), products from companies such as Ube Industries, Ltd., JSR Corporation, Asahi Kasei Co., Ltd., and Nippon Zeon Co., Ltd. can be used.

[0105] (d) Other rubber components

[0106] In addition, if necessary, as another rubber component, it may also include rubber (polymer) commonly used in tire production, such as nitrile rubber (NBR).

[0107] (2) Compound materials other than rubber components

[0108] (a) Resin composition

[0109] In this embodiment, from the perspective of imparting viscosity, the tread rubber composition contains a resin component. As described above, this content exceeds 25 parts by weight relative to 100 parts by weight of rubber component, and the ratio (Q / Wt), i.e., the ratio of Q (parts by weight) to the cross-sectional width Wt (mm), is greater than 0.1 (parts by weight). Q (parts by weight) is more preferably greater than 30 parts by weight, and even more preferably greater than 40 parts by weight. Furthermore, as described above, (Q / Wt) is preferably 0.12 or more, more preferably 0.15 or more, even more preferably greater than 0.15, even more preferably 0.17 or more, even more preferably 0.20 or more, even more preferably greater than 0.20, even more preferably 0.24 or more, and even more preferably 0.26 or more. On the other hand, it is preferably less than 0.35. Furthermore, since these resin components are thermoplastic, they also act as softeners together with the oil described later.

[0110] The resin components can be solid or liquid at room temperature. Specific examples of resin components include rosin resins, styrene resins, coumarin resins, terpene resins, C5 resins, C9 resins, C5C9 resins, and acrylic resins. Two or more of them can be used in combination.

[0111] Rosin resins are resins whose main component is rosin acid obtained through the processing of rosin. Rosin resins (rosin) can be classified according to whether they are modified or not, and can be divided into unmodified rosin (non-modified rosin) and modified rosin (rosin derivatives). Unmodified rosin includes, for example, tall rosin (also known as tall oil rosin), resin rosin, wood rosin, disproportionated rosin, polymerized rosin, hydrogenated rosin, and other chemically modified rosin. Modified rosin is a type of rosin modified from unmodified rosin, and examples include rosin esters, rosin modified with unsaturated carboxylic acids, rosin esters modified with unsaturated carboxylic acids, rosin amide compounds, and rosin amine salts.

[0112] Styrene resins are polymers that use styrene monomers as constituent monomers. Examples include polymers obtained by polymerizing styrene monomers as a major component (more than 50% by mass). Specifically, they include homopolymers obtained by polymerizing styrene monomers (styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc.) individually, copolymers obtained by copolymerizing two or more styrene monomers, and copolymers obtained by copolymerizing styrene monomers with other monomers that can be copolymerized with styrene monomers.

[0113] Other examples of monomers include acrylonitriles, such as acrylonitrile and methacrylates; unsaturated carboxylic acids, such as acrylic acid and methacrylates; unsaturated carboxylic acid esters, such as methyl acrylate and methyl methacrylate; dienes, such as chloroprene, butadiene, and isoprene; alkenes, such as 1-butene and 1-pentene; α,β-unsaturated carboxylic acids (such as maleic anhydride) and their anhydrides.

[0114] Coumarin-indene resin is preferred as a coumarone-based resin. Coumarin-indene resin is a resin containing coumarone and indene as monomeric components constituting the resin backbone (main chain). Examples of monomeric components in the backbone other than coumarone and indene include styrene, α-methylstyrene, methylindene, and vinyltoluene.

[0115] For example, relative to 100 parts by weight of rubber component, the content of coumarone-indene resin is greater than 1.0 parts by weight and less than 50.0 parts by weight.

[0116] The hydroxyl value (OH value) of coumarone-indene resin is, for example, greater than 15 mg KOH / g and less than 150 mg KOH / g. The OH value, expressed in milligrams, refers to the amount of potassium hydroxide required to neutralize the acetic acid bound to the hydroxyl group when 1 g of resin is acetylated. It is measured by potentiometric titration (JIS K 0070:1992).

[0117] The softening point of coumarone-indene resin is, for example, above 30°C and below 160°C. The softening point is the temperature at which the ball falls when measuring the softening point as defined in JIS K 6220-1:2001 using a ring-ball softening point measuring device.

[0118] Examples of terpene resins include polyterpenes, terpene phenols, and aromatically modified terpene resins. Polyterpenes are resins obtained by polymerizing terpene compounds and their hydrogenation products. Terpene compounds are compounds with the structure (C5H8). n Hydrocarbons that make up the composition of or their oxygen-containing derivatives, which are classified as monoterpenes (C 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32 Compounds with terpenes as their basic skeleton include α-pinene, β-pinene, dipentene, limonene, myrcene, allociperene, osimene, α-phellandrene, α-terpinene, γ-terpinene, terpinene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, and γ-terpineol.

[0119] Examples of polyterpenes include terpene resins made from the aforementioned terpene compounds, such as α-pinene resins, β-pinene resins, limonene resins, dipentene resins, and β-pinene / limonene resins, as well as hydrogenated terpene resins obtained by hydrogenating terpene resins. Examples of terpene phenols include resins obtained by copolymerizing the aforementioned terpene compounds and phenolic compounds, as well as resins obtained by hydrogenating the aforementioned resins. Specifically, resins obtained by condensing the aforementioned terpene compounds, phenolic compounds, and formalin are mentioned. Examples of phenolic compounds include phenol, bisphenol A, cresol, and xylenol. Examples of aromatically modified terpene resins include resins obtained by modifying terpene resins with aromatic compounds, as well as resins obtained by hydrogenating the aforementioned resins. There are no particular restrictions on aromatic compounds, as long as they are compounds with an aromatic ring. Examples include phenolic compounds, such as phenol, alkylphenol, alkoxyphenol and phenols containing unsaturated hydrocarbon groups; naphthol compounds, such as naphthol, alkylnaphthol, alkoxynaphthol and naphthols containing unsaturated hydrocarbon groups; styrene derivatives, such as styrene, alkylstyrene, alkoxystyrene and styrene containing unsaturated hydrocarbon groups; coumarone and indene.

[0120] Commercially available terpene resins, such as those from Yasuhara Chemical Co., Ltd., can be used. They can be used alone or in combination of two or more.

[0121] "C5 resin" refers to a resin obtained by polymerizing a C5 fraction. Examples of C5 fractions include petroleum fractions having 4 to 5 carbon atoms, such as cyclopentadiene, pentene, pentadiene, and isoprene. Dicyclopentadiene resin (DCPD resin) is preferred as a C5 type petroleum resin.

[0122] "C9 resin" refers to a resin obtained by polymerizing a C9 fraction, which can be hydrogenated or modified. Examples of C9 fractions include petroleum fractions having 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, and methylindene. Specific examples preferably include, for instance, coumarone-indene resins, coumarone resins, indene resins, and aromatic vinyl resins. As aromatic vinyl resins, homopolymers of α-methylstyrene or styrene, or copolymers of α-methylstyrene and styrene, are preferred because they are economical, easy to process, and have excellent heat dissipation properties. Copolymers of α-methylstyrene and styrene are more preferred. For example, commercially available resins from Clayton, Eastman Chemical, etc., can be used as aromatic vinyl resins.

[0123] "C5C9 resin" refers to a resin obtained by copolymerizing C5 and C9 fractions, which can be hydrogenated or modified. Examples of C5 and C9 fractions include the petroleum fractions mentioned above. Commercially available resins from companies such as Tosoh Corporation and LUHUA can be used as C5C9 resins.

[0124] There are no particular restrictions on acrylic resins; for example, solvent-free acrylic resins can be used.

[0125] As a solvent-free acrylic resin, (meth)acrylic resin (polymer) synthesized by high-temperature continuous polymerization (high-temperature continuous bulk polymerization: US4414370B, JP 84-6207A, JP 93-58805B, JP 89-313522A, US 5010166B, Toa Synthetic Research Annual Report TREND2000 No.3p42-45, etc.) is mentioned, and polymerization initiators, chain transfer agents, organic solvents, etc. are used as auxiliary raw materials as much as possible. In this invention, (meth)acrylic acid refers to methacrylic acid and acrylic acid.

[0126] Examples of monomeric components constituting acrylic resins include (meth)acrylic acid and (meth)acrylic acid derivatives, such as (meth)acrylates (alkyl esters, aryl esters, aralkyl esters, etc.), (meth)acrylamide, and (meth)acrylamide derivatives.

[0127] In addition, as a monomeric component constituting acrylic resins, aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, divinylnaphthalene, etc., can be used together with (meth)acrylic acid or (meth)acrylic acid derivatives.

[0128] Acrylic resins can be resins composed solely of (meth)acrylic acid, or resins containing components other than (meth)acrylic acid. Furthermore, acrylic resins can contain hydroxyl, carboxyl, or silanol groups, etc.

[0129] As a resin component, products from companies such as Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Toso Co., Ltd., Rutgers Chemicals Co., Ltd., BASF Co., Ltd., Arizona Chemical Co., Ltd., Nitto Chemical Co., Ltd., Nippon Catalyst Co., Ltd., JX Energy Co., Ltd., Arakawa Chemical Industry Co., Ltd., and Taoka Chemical Industry Co., Ltd. can be used.

[0130] (b) Packing

[0131] In this embodiment, the rubber composition preferably includes fillers. Specific examples of fillers include carbon black, silica, calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica. Silica is preferably used as a reinforcing agent to achieve low rolling resistance, and it is preferable to use silica in conjunction with a silane coupling agent. Carbon black is also preferably used as a reinforcing agent if necessary.

[0132] (b-1)Silica

[0133] The content of the rubber component relative to 100 parts by weight is preferably 40 parts by weight or more. There is no particular upper limit, as long as the rubber composition can be compounded, but it is preferably, for example, about 200 parts by weight. Therefore, silica is dispersed throughout the rubber system without uneven distribution in NR or SBR, thus further improving abrasion resistance and anti-slip properties.

[0134] As silicon dioxide, a BET specific surface area of ​​180 m² is preferred. 2 / g or more and 300m 2 The silica content is below / g. Therefore, the strengthening properties of silica can be further improved, resulting in particularly improved wear resistance. BET specific surface area refers to the nitrogen adsorption specific surface area (N2SA) measured according to the BET method of ASTM D3037-93.

[0135] Specific examples of silica include dry silica (anhydrous silica) and wet silica (hydrated silica). Wet silica is preferred because it contains a large number of silanol groups, and products from companies such as Evonik, Degussa, Rhodia, Tosoh Silica Co., Ltd., Solbay Japan Co., Ltd., and Tokuyama Co., Ltd. can be used.

[0136] (b-2) Silane coupling agent

[0137] The rubber composition preferably contains a silane coupling agent and silica. There are no particular limitations on the silane coupling agent. Examples of silane coupling agents include:

[0138] Sulfide-based silane coupling agents, such as bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)tetrasulfide, etc. Silyl ethyl) disulfide, bis(4-triethoxysilyl butyl) disulfide, bis(3-trimethoxysilyl propyl) disulfide, bis(2-triethoxysilyl ethyl) disulfide, bis(4-trimethoxysilyl butyl) disulfide, 3-trimethoxysilyl propyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-trimethoxysilyl ethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-trimethoxysilyl propyl methacrylate monosulfide;

[0139] Thiol-based silane coupling agents, such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and NXT and NXT-Z manufactured by Momentive;

[0140] Vinyl silane coupling agents, such as vinyltriethoxysilane and vinyltrimethoxysilane;

[0141] Aminosilane coupling agents, such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane;

[0142] Glycidyl ether oxysilane coupling agents, such as γ-glycidyl ether oxypropyltriethoxysilane and γ-glycidyl ether oxypropyltrimethoxysilane;

[0143] Nitrosilane coupling agents, such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and

[0144] Chlorinated silane coupling agents, such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. These can be used alone or in combination of two or more.

[0145] The preferred content of the silane coupling agent relative to 100 parts by weight of silica is, for example, greater than 3 parts by weight and less than 15 parts by weight. Specific silane coupling agents include, for example, products from Degussa, Momentive, Shinetsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., and Toray Dow Corning Co., Ltd.

[0146] For example, the content of silane coupling agent is greater than 3 parts by mass and less than 25 parts by mass relative to 100 parts by mass of silicon dioxide.

[0147] (b-3) Carbon black

[0148] The tread rubber composition preferably contains carbon black. The carbon black content is, for example, more than 1 part by weight and less than 200 parts by weight relative to 100 parts by weight of the rubber component.

[0149] There are no particular limitations on carbon black, and examples include furnace black (furnace black), such as SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF, and ECF; acetylene black; thermal cracking black (thermal cracking black), such as FT and MT; channel black (channel black), such as EPC, MPC, and CC; and graphite. These can be used alone or in combination of two or more.

[0150] The nitrogen adsorption specific surface area (N2SA) of carbon black is, for example, 30 m².2 / g or more and 250m 2 / g or less. The amount of dibutyl phthalate (DBP) absorbed by carbon black is, for example, more than 50 ml / 100g and less than 250 ml / 100g. The nitrogen adsorption specific surface area of ​​carbon black is measured according to ASTM D4820-93, and the amount of DBP absorbed is measured according to ASTM D2414-93.

[0151] There are no particular limitations on the specific carbon black used; examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available products include those from companies such as Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin Nikka Carbon Co., Ltd., and Columbia Carbon Co., Ltd. These can be used alone or in combination of two or more.

[0152] (b-4) Other fillers

[0153] In addition to the aforementioned carbon black and silica, the rubber composition may further contain fillers commonly used in the tire industry, such as calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica. For example, these contents are greater than 0.1 parts by weight and less than 200 parts by weight relative to 100 parts by weight of the rubber component.

[0154] (c) Softener

[0155] The tread rubber composition may contain oil (including extended oil) or liquid rubber as a softener. The total softener content is preferably greater than 1 part by weight and less than 10 parts by weight per 100 parts by weight of the rubber component. The oil content also includes the amount of oil contained in the rubber (oil-extended rubber).

[0156] Examples of oils include mineral oils (generally referred to as processed oils), vegetable oils, or mixtures thereof. Examples of mineral oils (processed oils) include paraffin-processed oils, aromatic processed oils, naphthenic processed oils, etc. Examples of vegetable oils and fats include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice bran oil, beni flower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. These can be used alone or in combination of two or more.

[0157] Specific examples of processed oils (mineral oils) include products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Japan Energy Co., Ltd., Olisoy Co., Ltd., H&R Co., Ltd., Toyokuni Seiyu Co., Ltd., Showa Shell Sekiyu Co., Ltd., and Fuji Kosan Co., Ltd.

[0158] Liquid rubber, mentioned as a softener, is a polymer that exists in a liquid state at room temperature (25°C) and is a polymer with monomers similar to those in solid rubber as constituent elements. Examples of liquid rubber include farnesene polymers, liquid diene polymers, and their hydrogenated additives.

[0159] Farnesene polymers are polymers obtained by polymerizing farnesenes and have farnesene-based structural units. Farnesenes include isomers such as α-farnesene ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodecathetene) and β-farnesene (7,11-dimethyl-3-methylene-1,6,10-dodecathetene).

[0160] Farnesene polymers can be homopolymers of farnesene (farnesene homopolymers) or copolymers of farnesene and vinyl monomers (farnesene-vinyl monomer copolymers).

[0161] Examples of liquid diene polymers include liquid styrene-butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), and liquid styrene-isoprene copolymer (liquid SIR).

[0162] The polystyrene equivalent weight-average molecular weight (Mw) of the liquid diene polymer, as determined by gel permeation chromatography (GPC), is, for example, greater than 1.0 × 10⁻⁶. 3 And less than 2.0 × 10 5 In this specification, the Mw of the liquid diene polymer is the polystyrene conversion value determined by gel permeation chromatography (GPC).

[0163] The content of liquid rubber (total content of liquid farnesene polymers, liquid diene polymers, etc.) is, for example, greater than 1 part by mass and less than 100 parts by mass relative to 100 parts by mass of rubber component.

[0164] As a liquid rubber, products from Kuraray Co., Ltd. and Clay Valley Co., Ltd. can be used, for example.

[0165] (d) Anti-aging agents

[0166] The tread rubber composition preferably contains an anti-aging agent. For example, the content of the anti-aging agent is more than 1 part by weight and less than 10 parts by weight relative to 100 parts by weight of the rubber component.

[0167] Examples of anti-aging agents include naphthylamine anti-aging agents, such as phenyl-α-naphthylamine; diphenylamine anti-aging agents, such as octyl diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; p-phenylenediamine anti-aging agents, such as N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, and N,N'-di-2-naphthyl-p-phenylenediamine; quinoline anti-aging agents, such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenolic anti-aging agents, such as 2,6-di-tert-butyl-4-methylphenol and styreneated phenol; and bis, tri, and polyphenolic anti-aging agents, such as tetrakis[3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate methane]. These can be used alone or in combination of two or more.

[0168] As an anti-aging agent, products from companies such as Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexsys Co., Ltd., etc. can be used.

[0169] (e) Stearic acid

[0170] The tread rubber composition may contain stearic acid. For example, the stearic acid content is 0.5 parts by weight or more and 10.0 parts by weight or less per 100 parts by weight of the rubber component. As stearic acid, conventionally known stearic acids can be used, such as products from NOF Corporation, Kao Corporation, Fuji film Wako Pure Chemical Industries, Ltd., and Chiba Fatty Acid Co., Ltd.

[0171] (f) Zinc oxide

[0172] The tread rubber composition may contain zinc oxide (zinc white). For example, the zinc oxide content is 0.5 parts by weight or more and 10 parts by weight or less per 100 parts by weight of the rubber component. Conventionally known zinc oxides can be used as the zinc oxide, such as products from Mitsui Metal Mining Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Shodo Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc.

[0173] (g) wax

[0174] The tread rubber composition preferably contains wax. For example, the wax content is 0.5 to 20 parts by weight, preferably 1.5 to 15 parts by weight, and more preferably 3.0 to 10.0 parts by weight, relative to 100 parts by weight of the rubber component.

[0175] There are no particular limitations on the types of waxes used; examples include petroleum waxes such as paraffin and microcrystalline wax; natural waxes such as plant waxes and animal waxes; and synthetic waxes such as polymers of ethylene or propylene. These can be used alone or in combination of two or more.

[0176] As a wax, for example, products from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Seiko Chemical Industry Co., Ltd., etc. can be used.

[0177] (h) Crosslinking agents and vulcanization accelerators

[0178] The tread rubber composition preferably contains a crosslinking agent, such as sulfur. For example, the content of the crosslinking agent is 0.1 parts by weight or more and 10.0 parts by weight or less relative to 100 parts by weight of the rubber component.

[0179] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, and soluble sulfur, which are commonly used in the rubber industry. These can be used alone or in combination of two or more.

[0180] For example, products from companies such as Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemicals Corporation, Flexsys Co., Ltd., Nippon KanryoKogyo Co., Ltd., and Hosoi Chemical Industry Co., Ltd. can be used as sulfur.

[0181] Examples of crosslinking agents other than sulfur include sulfur-containing vulcanizing agents, such as Tackirol V200 manufactured by Taoka Chemical Industry Co., Ltd., DURALINK HTS (1,6-hexamethylene-sodium dithiosulfate dihydrate) manufactured by Flexsys, and KA9188 (1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane) manufactured by Lanxess; and organic peroxides, such as dicumyl peroxide.

[0182] The tread rubber composition preferably contains a vulcanization accelerator. For example, the content of the vulcanization accelerator is 0.3 parts by weight or more and 10.0 parts by weight or less relative to 100 parts by weight of the rubber component.

[0183] Examples of vulcanization accelerators include:

[0184] Thiazole vulcanization accelerators, such as 2-mercaptobenzothiazole, di-2-benzothiazole disulfide and N-cyclohexyl-2-benzothiamide;

[0185] Thiuram-based vulcanization accelerators, such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetra(2-ethylhexyl)thiuram disulfide (TOT-N);

[0186] Sulfimide-based vulcanization accelerators, such as N-cyclohexyl-2-benzothiazole sulfinamide, N-tert-butyl-2-benzothiazole sulfinamide, N-oxyethylidene-2-benzothiazole sulfinamide, N-oxyethylidene-2-benzothiazole sulfinamide and N,N'-diisopropyl-2-benzothiazole sulfinamide;

[0187] And guanidine vulcanization accelerators, such as diphenylguanidine, di-o-tolylguanidine and o-tolylguanidine.

[0188] These can be used individually or in combination of two or more.

[0189] (i) Other

[0190] In addition to the components mentioned above, the tread rubber composition may also contain additives commonly used in the tire industry, such as fatty acid metal salts, carboxylic acid metal salts, organic peroxides, and graphite. For example, the content of these additives is greater than 0.1 parts by weight and less than 200 parts by weight relative to 100 parts by weight of the rubber component.

[0191] 2. Production of tread rubber composition

[0192] The tread rubber composition is produced by a conventional method, for example, a manufacturing method comprising the following steps: a basic mixing step in which the rubber component is mixed with a filler (such as silica or carbon black), and a fine mixing step in which the mixture obtained in the basic mixing step is mixed with a crosslinking agent.

[0193] Mixing can be carried out using known (sealed) mixing machines such as Banbury mixers, mixing mills, or open rolls.

[0194] The mixing temperature in the basic mixing step is, for example, above 50°C and below 200°C, and the mixing time is, for example, above 30 seconds and below 30 minutes. In addition to the above-mentioned components, in the basic mixing process, compounding agents commonly used in the rubber industry, such as softeners (e.g., oils, stearic acid, zinc oxide), anti-aging agents, waxes, and vulcanization accelerators, may be added and mixed as needed.

[0195] In the fine mixing step, the compounded product obtained in the basic mixing step and the crosslinking agent are mixed. The mixing temperature in the fine mixing step is, for example, above room temperature and below 80°C, and the mixing time is, for example, above 1 minute and below 15 minutes. In addition to the above-mentioned components, vulcanization accelerators, zinc oxide, etc., may be added and mixed appropriately as needed in the fine mixing step.

[0196] 3. Tire manufacturing

[0197] The tire of the present invention is manufactured using an uncured rubber composition obtained through a refining step by conventional methods. In other words, the uncured rubber composition is extruded according to the shape of each tire component of the tread and formed together with other tire components on a tire forming machine by conventional methods to produce an uncured tire.

[0198] Specifically, on a molded roller, an inner liner (ensuring tire airtightness), a tire carcass (bearing the load, impact, and inflation pressure), and a belt (for tightening the carcass to increase tread rigidity) are wound. The two ends of the carcass are fixed to two sides, and bead portions (for securing the tire to the rim) are arranged in a ring. Then, the tread is bonded to the center of the outer periphery, and the sidewall portions (protecting the carcass and resisting bending) are bonded to the radially outer side to produce an uncured tire.

[0199] In this embodiment, it is preferable that the belt is provided as an inclined belt layer extending at an angle of 55° or more and 75° or less relative to the tire circumferential direction. Therefore, tire durability is ensured while maintaining sufficient tread rigidity.

[0200] The uncured tires are then heated and pressed in a vulcanizing machine to obtain a tire. The vulcanization step can be carried out using known vulcanization methods. The vulcanization temperature is, for example, above 120°C and below 200°C, and the vulcanization time is, for example, above 5 minutes and below 15 minutes.

[0201] At this point, the tire is formed into a shape that satisfies Equation 1 above.

[0202] The specific tires that can satisfy Formula 1 above include 145 / 60R18, 145 / 60R19, 155 / 55R18, 155 / 55R19, 155 / 70R17, 155 / 70R19, 165 / 55R20, 165 / 55R21, 165 / 60R19, 165 / 65R19, 165 / 70R18, 175 / 55R19, 175 / 55R20, 175 / 55R22, 175 / 60R18, 185 / 55R19, 185 / 60R20, 195 / 50R20, and 195 / 55R20.

[0203] In this embodiment, the tire satisfying Formula 1 above is preferably applied to the pneumatic tire of a passenger car, and by using the above tread rubber composition and forming the tread portion by satisfying the above formula, it can more preferably help to solve the problem in the present invention, namely, to improve handling stability when driving in the rain.

[0204] The pneumatic tires for passenger cars mentioned above refer to tires installed on four-wheeled vehicles with a maximum load capacity of 1000 kg or less. Here, maximum load capacity refers to the maximum load capacity determined for each tire according to standards within the standard system upon which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Association), it is the maximum load capacity based on the load index (LI); in the case of TRA (The Tire and Rim Association, Inc.), it is the maximum value described in "Tire Load Limits at Various Cold Inflation Pressures"; and in the case of ETRO (The European Tire and Rim Technical Organization), it is the "inflation pressure". For tires not specified in these standards, the maximum load capacity should be calculated using the following formula.

[0205] Maximum load capacity (kg) = 0.000011 × V + 175

[0206] V: Imaginary volume of the tire (mm) 3 )

[0207] There is no particular limitation on the maximum load capacity, as long as it is below 1000 kg. However, generally speaking, as the maximum load capacity increases, the tire weight tends to increase, and the braking distance also increases accordingly due to inertia. Therefore, the maximum load capacity is preferably below 900 kg, more preferably below 800 kg, and even more preferably below 700 kg.

[0208] From the perspective of braking distance due to inertia, the tire weight is preferably 20 kg or less, more preferably 15 kg or less, and even more preferably 12 kg or less, 10 kg or less, and 8 kg or less. The tire of the present invention can be equipped with electronic components; in this case, the tire weight referred to herein includes the weight of the electronic components and the electronic component mounting components. If sealants, sponges, etc., are provided in the cavity, the tire weight includes them.

[0209] Example

[0210] The present invention will now be described in more detail with reference to embodiments.

[0211] 1. Manufacturing of rubber compositions for tire treads

[0212] First, produce the rubber composition for tire tread.

[0213] (1) Mixed materials

[0214] First, prepare the following mixtures.

[0215] (a) Rubber composition

[0216] (a-1)NR: RSS#3

[0217] (a-2)SBR: NS116 manufactured by JSR Corporation (styrene content: 20% by mass)

[0218] (a-3)BR: UBEPOL BR150B manufactured by Ube Industries, Ltd.

[0219] (b) Compounds other than rubber components

[0220] (b-1) Carbon black: Show Black N220 (N2SA: 111m2 / g, DBP: 115ml / 100g) manufactured by Cabot Japan Co., Ltd.

[0221] (b-2) Silica: Ultrasil VN3 (N2SA: 175m) manufactured by Degussa. 2 / g)

[0222] (b-3) Silane coupling agent: Si69 (bis(3-triethoxysilylpropyl)tetrasulfide) manufactured by Degussa

[0223] (b-4) Craft oil: Craft X-140 (fragrant oil) manufactured by Japan Energy Co., Ltd.

[0224] (b-5) Resin composition: Sylvatraxx 4401 (a copolymer of α-methylstyrene and styrene) manufactured by Kraton.

[0225] (b-6) Zinc White: Two types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd.

[0226] (b-7) Stearic acid: Stearic acid "Tsubaki" manufactured by NOF Corporation.

[0227] (b-8) Anti-aging agent: Nocrac6C (N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0228] (b-9) Wax: Sannok wax manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0229] (b-10) Crosslinking agents and vulcanization accelerators

[0230] Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd.

[0231] Vulcanization accelerator-1: NoccelerCZ (N-cyclohexyl-2-benzothiazolylsulfonamide) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0232] Vulcanization accelerator-2: NoccelerD (N,N'-diphenylguanidine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0233] (2) Manufacturing of rubber compositions

[0234] Table 1 shows the amounts (parts by mass) of each compound material excluding the resin component. The amounts (parts by mass) of the resin component are those shown in Tables 2 to 4.

[0235] [Table 1]

[0236] Compounding materials Compounding amounts NR 20 SBR 60 BR 20 Carbon black 10 Silica 60 Silane coupling agent 5 Oil 3 Zinc oxide 2.5 Stearic acid 2 Anti-aging agent 1.5 Wax 1 Sulfur 1.5 Vulcanization accelerator-1 1 Vulcanization accelerator-2 1

[0237] In the compound materials shown in Table 1, all compound materials except sulfur, vulcanization accelerator-1 and vulcanization accelerator-2 are mixed with the resin components at 150°C for 5 minutes to obtain the compound product.

[0238] 2. Tire manufacturing

[0239] Next, sulfur and a vulcanization accelerator were added to the obtained compound, and the mixture was kneaded at 80°C with an open roller for 5 minutes to obtain a tread rubber composition. The obtained tread rubber composition was used to form a tread, which was then bonded to other tire components to form an unvulcanized tire. This tire was then vulcanized at 170°C for 10 minutes to produce test tires with sizes of 155 (Table 2), 205 (Table 3), or 245 (Table 4).

[0240] Then, the cross-sectional width Wt (mm), outer diameter Dt (mm), cross-sectional height Ht (mm), and aspect ratio (%) of each test tire were measured, and the hypothetical volume V (mm²) was calculated. 3 ).

[0241] Then, calculate (Dt-2×Ht) and (V+1.5×10). 7 ) / Wt、(V+2.0×10 7 ) / Wt、(V+2.5×10 7 ) / Wt and Q / Wt. The results are shown in Table 2-4.

[0242] 3. Evaluation of handling stability

[0243] (1) Test method

[0244] All test tires were installed on all wheels of a domestically produced FF car (2000cc engine). After inflating the tires to an internal pressure of 250 kPa, the car was driven at 40 km / h and 120 km / h on a wet test track. Drivers evaluated the changes in handling performance caused by the changes in speed using a five-point scale, from 1 (significant change) to 5 (almost no change). The total scores from the 20 drivers were then calculated.

[0245] Then, the results of the tires used as evaluation references (Comparative Examples 1-2 in Table 2, Comparative Examples 2-2 in Table 3, and Comparative Examples 3-3 in Table 4) were set to 100, and the calculated results were indexed into a wet handling stability index based on the following formula. The higher the value, the better the handling stability when driving at high speeds on wet surfaces.

[0246] Wet handling stability index = [(test tire result) / (reference tire result)] × 100

[0247] (2) Evaluation Results

[0248] Table 2 shows the evaluation results for size 155, Table 3 shows the evaluation results for size 205, and Table 4 shows the evaluation results for size 245.

[0249] [Table 2]

[0250]

[0251] [Table 3]

[0252]

[0253] [Table 4]

[0254]

[0255] As can be seen from Tables 2 to 4, in any size tire of 155, 205, or 245, when the amount of resin component Q is 1 / 4 of the amount of rubber component (i.e., 25 parts by mass per 100 parts by mass of rubber component) and satisfies Equations 1 and 2 above, the wet handling stability index exceeds 100, which can provide a pneumatic tire with sufficiently improved handling stability when driving at high speeds on wet roads.

[0256] Furthermore, it should be understood that by satisfying the requirements of the present invention (2) and thereafter, the wet handling stability index can be further improved, and pneumatic tires with further improved handling stability at high speeds on wet surfaces can be provided.

[0257] On the other hand, when the amount of resin component Q is less than 1 / 4 of the amount of rubber component (less than 25 parts by mass relative to 100 parts by mass of rubber component), or when Formula 1 or Formula 2 is not satisfied, the wet handling stability index is less than 100, and it cannot be said that the handling stability is sufficiently improved when driving at high speed on wet road surfaces.

[0258] Although the present invention has been described above according to embodiments, the present invention is not limited to the above embodiments. Various modifications can be made to the above embodiments within the same and equivalent scope as the present invention.

[0259] The present invention (1) is:

[0260] A pneumatic tire, wherein

[0261] The tread portion is formed of a rubber composition containing styrene-butadiene rubber and isoprene rubber as rubber components, as well as resin components.

[0262] Relative to 100 parts by weight of the rubber component, the content Q (parts by weight) of the resin component exceeds 25 parts by weight, and

[0263] Satisfy the following equations 1 and 2:

[0264] 1600≦(Dt 2 (×π / 4) / Wt≦2827.4···Equation 1

[0265] Q / Wt>0.1···Equation 2,

[0266] Wherein, relative to 100 parts by mass of the rubber component, the content of the resin component is Q (parts by mass), and when the tire is mounted on a standardized rim and the internal pressure is 250 kPa, the cross-sectional width of the tire is Wt (mm), and the outer diameter of the tire is Dt (mm).

[0267] The present invention (2) is a pneumatic tire as described in the present invention (1), wherein in 100 parts by mass of the rubber component, when the amount of styrene-butadiene rubber is R1 (parts by mass) and the amount of isoprene rubber is R2 (parts by mass), the following formulas 3 and 4 are satisfied.

[0268] R1 + R2 ≧ 60 ··· Formula 3

[0269] 50 < R1 ≦ 80 ··· Formula 4.

[0270] The present invention (3) is a pneumatic tire as described in the present invention (1) or (2), wherein the following formula is satisfied:

[0271] 1865 ≦ (Dt 2 × π / 4) / Wt.

[0272] The present invention (4) is a pneumatic tire which is any combination of the present invention (1) to (3), wherein the content Q (parts by mass) of the resin component is more than 30 parts by mass with respect to 100 parts by mass of the rubber component.

[0273] The present invention (5) is a pneumatic tire which is any combination of the present invention (1) to (4), wherein the following formula 5 is satisfied:

[0274] Q / Wt > 0.15 ··· Formula 5.

[0275] The present invention (6) is a pneumatic tire which is any combination of the present invention (1) to (5), wherein the following formula 6 is satisfied:

[0276] Q / Wt < 0.35 ··· Formula 6.

[0277] The present invention (7) is a pneumatic tire which is any combination of the present invention (1) to (6), wherein the weight-average molecular weight of the styrene-butadiene rubber is 100,000 or more and 2,000,000 or less.

[0278] The present invention (8) is a pneumatic tire which is any combination of the present invention (1) to (7), wherein the styrene-butadiene rubber is a modified solution-polymerized styrene-butadiene rubber.

[0279] The present invention (9) is a pneumatic tire which is any combination of the present invention (1) to (8), wherein the styrene content in the styrene-butadiene rubber is 5% or more and 25% or less.

[0280] The present invention (10) is a pneumatic tire which is any combination of the present invention (1) to (9), wherein the styrene content in the rubber composition is 1% or more and 5% or less.

[0281] The present invention (11) is an inflatable tire of any combination of the present invention (1) to (10), wherein the rubber composition further contains less than 40 parts by mass of butadiene rubber relative to 100 parts by mass of the rubber component.

[0282] The present invention (12) is an inflatable tire of any combination of the present invention (1) to (11), wherein the resin component is selected from the group consisting of C5 resin, C5-C9 resin, C9 resin, terpene resin, terpene-aromatic compound resin, rosin resin, dicyclopentadiene resin and alkylphenol resin.

[0283] The present invention (13) is an inflatable tire of any combination of the present invention (1) to (12), wherein the rubber composition contains 40 or more parts by mass of silica relative to 100 parts by mass of the rubber component.

[0284] The present invention (14) is a pneumatic tire as described in the present invention (13), wherein the BET specific surface area of ​​the silica is 180 m². 2 / g or more and 300m 2 / g or less.

[0285] The present invention (15) is an inflatable tire as described in the present invention (13) or (14), wherein, relative to 100 parts by weight of the silica, it contains more than 3 parts by weight and less than 15 parts by weight of a silane coupling agent.

[0286] The present invention (16) is an inflatable tire of any combination of the present invention (1) to (15) having an aspect ratio of 40% or more.

[0287] The present invention (17) is an inflatable tire of any combination of the present invention (1) to (16), wherein the outer diameter Dt (mm) is less than 843 mm.

[0288] The present invention (18) is an inflatable tire of any combination of the present invention (1) to (17), wherein the cross-sectional width Wt (mm) is less than 305mm.

[0289] The present invention (19) is an inflatable tire of any combination of the present invention (1) to (18), wherein (Dt-2×Ht) is 430 (mm) or more, wherein when the tire is mounted on a standardized rim and the internal pressure is 250 kPa, the outer diameter of the tire is Dt (mm) and the cross-sectional height of the tire is Ht (mm).

[0290] The present invention (20) is an inflatable tire of any combination of the present invention (1) to (19), wherein, when the cross-sectional width of the tire is Wt (mm), the outer diameter is Dt (mm), and the cross-sectional height is Ht (mm), and when the tire is mounted on a standardized rim and the internal pressure is 250 kPa, the imaginary volume V (mm²) of the tire is... 3 That is, the space occupied by the tire and Wt satisfy the following formula:

[0291] [(V+1.5×10 7 ) / Wt]≦4.02×10 5 .

[0292] The present invention (21) is a pneumatic tire as described in the present invention (20), wherein the following formula is satisfied:

[0293] [(V+2.0×10 7 ) / Wt]≦4.02×10 5 .

[0294] The present invention (22) is a pneumatic tire as described in the present invention (21), wherein the following formula is satisfied:

[0295] [(V+2.5×10 7 ) / Wt]≦4.02×10 5 .

[0296] The present invention (23) is an inflatable tire of any combination of the present invention (1) to (22), which is an inflatable tire for passenger vehicles.

Claims

1. A pneumatic tire, wherein The tread portion is formed of a rubber composition containing styrene-butadiene rubber and isoprene rubber as rubber components, as well as resin components. The content Q (parts by mass) of the resin component exceeds 40 parts by mass relative to 100 parts by mass of the rubber component, and Satisfy the following equations 1 and 2: 1600 ≦ (Dt 2 ×π / 4) / Wt ≦ 2827.4・・・Equation 1 Q / Wt ≧ 0.2 ・・・Equation 2, in, The content of the resin component is Q (parts by mass) relative to 100 parts by mass of the rubber component, and when the tire is mounted on a standardized rim and the internal pressure is 250 kPa, the cross-sectional width of the tire is Wt (mm) and the outer diameter of the tire is Dt (mm).

2. The pneumatic tire as claimed in claim 1, wherein, In 100 parts by mass of the rubber composition, when the amount of styrene-butadiene rubber is R1 (parts by mass) and the amount of isoprene rubber is R2 (parts by mass), the following equations 3 and 4 are satisfied. R1+R2 ≧ 60 ・・・Equation 3 50 < R1 ≦ 80・・・Form 4.

3. The pneumatic tire as described in claim 1 or 2, wherein, Satisfy the following formula: 1865 ≦ (Dt 2 ×π / 4) / Wt。 4. The pneumatic tire as described in claim 1 or 2, wherein, Satisfy the following equation 6: Q / Wt < 0.35 ・・・Equation 6.

5. The pneumatic tire as described in claim 1 or 2, wherein, The styrene-butadiene rubber has a weight-average molecular weight of 100,000 or more and 2,000,000 or less.

6. The pneumatic tire as described in claim 1 or 2, wherein, The styrene-butadiene rubber is a modified solution-polymerized styrene-butadiene rubber.

7. The pneumatic tire as claimed in claim 1 or 2, wherein, The styrene content in the styrene-butadiene rubber is more than 5% by mass and less than 25% by mass.

8. The pneumatic tire as claimed in claim 1 or 2, wherein, The styrene content in the rubber composition is more than 1% by mass and less than 5% by mass.

9. The pneumatic tire as claimed in claim 1 or 2, wherein, The rubber composition further contains less than 40 parts by weight of butadiene rubber relative to 100 parts by weight of the rubber component.

10. The pneumatic tire as claimed in claim 1 or 2, wherein, The resin components are selected from the group consisting of C5 resins, C5-C9 resins, C9 resins, terpene resins, terpene-aromatic compound resins, rosin resins, dicyclopentadiene resins, and alkylphenol resins.

11. The pneumatic tire as claimed in claim 1 or 2, wherein, The rubber composition contains 40 or more parts by mass of silica relative to 100 parts by mass of the rubber component.

12. The pneumatic tire of claim 11, wherein, The BET specific surface area of ​​the silica is 180 m². 2 / g or more and 300 m 2 / g or less.

13. The pneumatic tire of claim 11, wherein, The silica contains more than 3 parts by mass and less than 15 parts by mass of silane coupling agent relative to 100 parts by mass.

14. The pneumatic tire as described in claim 1 or 2, wherein the aspect ratio is 40% or more.

15. The pneumatic tire as claimed in claim 1 or 2, wherein, The outer diameter Dt (mm) is less than 843 mm.

16. The pneumatic tire as claimed in claim 1 or 2, wherein, The cross-sectional width Wt (mm) is less than 305 mm.

17. The pneumatic tire as claimed in claim 1 or 2, wherein, (Dt−2×Ht) is 430 (mm) or more, wherein when the tire is mounted on a standardized rim and the internal pressure is 250 kPa, the outer diameter of the tire is Dt (mm) and the cross-sectional height of the tire is Ht (mm).

18. The pneumatic tire as claimed in claim 1 or 2, wherein, When the tire has a cross-sectional width of Wt (mm), an outer diameter of Dt (mm), and a cross-sectional height of Ht (mm), and when the tire is mounted on a standardized rim with an internal pressure of 250 kPa, the imaginary volume V (mm²) of the tire is... 3 That is, the space occupied by the tire and Wt satisfy the following formula: [(V + 1.5×10 7 ) / Wt] ≦ 4.02×10 5 。 19. The pneumatic tire of claim 18, wherein, Satisfy the following formula: [(V + 2.0×10 7 ) / Wt] ≦ 4.02×10 5 。 20. The pneumatic tire of claim 19, wherein the following formula is satisfied: [(V + 2.5×10 7 ) / Wt] ≦ 4.02×10 5 。 21. The pneumatic tire as described in claim 1 or 2, wherein it is a pneumatic tire for a passenger vehicle.

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