pneumatic tires

Abstract

Provided is a pneumatic tire that ensures sufficient steering stability even when a vehicle travels on a wet road surface at a high speed. The pneumatic tire includes a tread part formed of a rubber composition containing: a rubber component of styrene-butadiene rubber and isoprene-based rubber; and a resin component, wherein when Q (parts by mass) is the content of the resin component with respect to 100 parts by mass of the rubber component, the tire is incorporated into a normal rim, the internal pressure is 250 kPa, Wt (mm) is the cross-sectional width of the tire, and Dt (mm) is the outer diameter, the content Q (parts by mass) of the resin component with respect to 100 parts by mass of the rubber component exceeds 25 parts by mass, and expression (1) and expression (2) are satisfied. 1600≦(Dt2×π / 4) / Wt≦2827.4……(1) Q / Wt>0.1……(2)

Description

[Technical Field]

[0001] The present disclosure relates to pneumatic tires. [Background technology]

[0002] In recent years, due to growing concerns about environmental issues and economic considerations, there has been a growing demand for automobiles to have lower fuel consumption, and there is also a demand for improved fuel efficiency in the pneumatic tires (hereinafter simply referred to as "tires") that are fitted to automobiles.

[0003] Conventionally, a specific means for improving the fuel economy of tires has generally been to apply a terminal-modified polymer to synthetic rubber and form the tread portion using a tire compound containing modified synthetic rubber in which the polymer molecular weight is reduced and the number of terminals is increased in order to improve the modification effect.

[0004] However, in such tire compounds, the molecular weight of the polymers contained in the compound is low, which may result in reduced breaking strength and abrasion resistance of the finished tire.

[0005] Therefore, it has been proposed to improve the breaking strength and abrasion resistance while maintaining low fuel consumption (low rolling resistance) by adding an isoprene-based rubber, which has excellent breaking strength, to the above-mentioned modified synthetic rubber to form the rubber component of the tread portion (for example, Patent Documents 1 to 4). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-213836 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-52329 [Patent Document 3] Japanese Patent Application Publication No. 2018-154181 [Patent Document 4] JP 2019-85445 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, tires based on these conventional technologies have the risk of reducing grip on the road surface and causing deterioration in handling stability, particularly when traveling at high speeds on wet road surfaces, and further improvements are therefore required.

[0008] Therefore, an object of the present disclosure is to provide a pneumatic tire that ensures sufficient steering stability even when traveling at high speeds on wet road surfaces. [Means for solving the problem]

[0009] The present inventors have conducted extensive research into solving the above problems, and have found that the above problems can be solved by the disclosure described below, leading to the completion of the present disclosure.

[0010] The present disclosure provides: The tread portion is formed of a rubber composition containing styrene-butadiene rubber and isoprene-based rubber as rubber components and also containing a resin component, The content of the resin component relative to 100 parts by mass of the rubber component is Q (parts by mass), When mounted on a standard rim and the internal pressure is 250 kPa, the tire cross-sectional width is Wt (mm) and the outer diameter is Dt (mm). a content Q (parts by mass) of the resin component relative to 100 parts by mass of the rubber component is more than 25 parts by mass, The pneumatic tire is characterized by satisfying the following (Equation 1) and (Equation 2). 1600≦(Dt 2 ×π / 4) / Wt≦2827.4 (Formula 1) Q / Wt≧ 0.26 ··············(Formula 2) [Effects of the Invention]

[0011] According to the present disclosure, it is possible to provide a pneumatic tire that ensures sufficient steering stability even when traveling at high speeds on wet road surfaces. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, the present disclosure will be specifically described based on embodiments.

[0013] [1] Features of the tire disclosed First, the features of the tire according to the present disclosure will be described.

[0014] The present inventors believed that in order to obtain a pneumatic tire that ensures sufficient handling stability even when running at high speeds on wet roads, conventional techniques that simply control the rubber physical properties through compounding are insufficient, and that it is necessary to consider the tire shape in addition to the physical properties of the rubber composition that forms the tread portion (hereinafter also referred to as the "tread rubber composition"). As a result of various experiments and considerations, they have completed the present disclosure.

[0015] First, the tire according to the present disclosure has a tire shape in which the area when viewed from the side of the tire is larger than the cross-sectional width of the tire within a predetermined range. This reduces the number of repeated deformations per unit time, and as a result, the time available for heat exchange is extended. This improves the heat dissipation performance of the side portion, thereby achieving sufficient fuel efficiency.

[0016] Specifically, when the tire is mounted on a regular rim and the internal pressure is 250 kPa, the tire cross-sectional width is Wt (mm) and the outer diameter is Dt (mm). 2 If the tire shape satisfies the condition of (×π / 4) / Wt≦2827.4, the area (mm ) of the tire when viewed from the side is the same as the cross-sectional width Wt (mm). 2 ), i.e., [(Dt / 2) 2 ×π)=(Dt 2×π / 4) is appropriately ensured, improving the heat dissipation properties of the side portions, thereby sufficiently reducing rolling resistance and achieving low fuel consumption. Note that a value of 1700 or higher is more preferable, and 1865 or higher is even more preferable. Furthermore, a value of 1963.4 or higher is even more preferable, 1979 or higher is even more preferable, 1981 or higher is even more preferable, 2018 or higher, and 2480 or higher is even more preferable.

[0017] In the above description, "genuine rim" refers to the rim that is specified for each tire in the standard system that includes the standard on which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Manufacturers Association), it is the standard rim for the applicable size listed in the "JATMA YEAR BOOK", ETRTO (The European Tyre and Rim Manufacturers Association), For tires not specified in the standard, it refers to the rim with the smallest rim diameter and the next narrowest rim width that can be mounted on a rim and can maintain internal pressure, i.e., that does not cause air leakage between the rim and tire.

[0018] In the above description, the outer diameter Dt (mm) of the tire is the outer diameter of the tire when it is mounted on a standard rim, the internal pressure is set to 250 kPa, and the cross-sectional width Wt of the tire is the width obtained by excluding the patterns, letters, etc. on the side of the tire from the straight-line distance between the sidewalls (total width of the tire) including all patterns, letters, etc. on the side of the tire when the tire is mounted on a standard rim, the internal pressure is set to 250 kPa, and the tire is under no load.

[0019] However, if a tire with the above-mentioned shape is manufactured, the centrifugal force during rolling will be large, and the radius of the tire will increase during rolling, which is thought to result in uneven contact pressure and a deterioration in handling stability when running at high speeds on wet roads.In particular, the wider the cross-sectional width Wt of a tire, the greater the difference between the contact pressure at the tread center and the contact pressure at the tread shoulders will likely be, which is thought to be more likely to lead to a deterioration in handling stability.

[0020] To solve this problem, the present inventors came up with the idea of ​​using a rubber composition for forming the tread portion that contains, as rubber components, styrene butadiene rubber (SBR), which has high heat buildup and excellent grip, and isoprene-based rubber, which has excellent breaking strength, as well as a rubber composition that contains a larger amount of resin component. That is, if the amount of resin component is increased according to the cross-sectional width Wt, the resin component can be sufficiently distributed to the surface of the tread shoulder portion, where ground pressure tends to be low, so that the adhesiveness of the resin component ensures grip on the road surface even during high-speed driving, thereby improving handling stability.

[0021] Specifically, when the content of the resin component with respect to 100 parts by mass of the rubber component is Q (parts by mass), Q is contained in an amount exceeding 25 parts by mass, i.e., more than 1 / 4, and the ratio of Q (parts by mass) to the cross-sectional width Wt (mm) (Q / Wt) is 0.26 or more By doing so, it is possible to achieve a significant improvement in steering stability over the entire tread, and therefore it is possible to provide a pneumatic tire with sufficiently improved steering stability when traveling at high speeds on wet road surfaces.

[0022] From the viewpoint of ensuring sufficient grip on the road surface due to the adhesiveness of the resin component, 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. 、( Q / Wt) is 0. 26 or above Ri, one On the other hand, it is preferably less than 0.35.

[0023] [2] More preferred embodiments of the tire according to the present disclosure The tire according to the present disclosure can achieve even greater effects by adopting the following aspects.

[0024] 1. Flatness The tire according to the present disclosure preferably has an aspect ratio of 40% or more, which allows the height of the side portion of the tire to be increased and local deformation of the tire to be suppressed, thereby further improving the durability of the tire.

[0025] The above-mentioned aspect ratio (%) can be calculated by the following formula using the tire cross-sectional height Ht (mm) (the distance from the bottom of the bead to the outermost surface of the tread, which is half the difference between the tire outer diameter and the nominal rim diameter) and the cross-sectional width Wt (mm) when the internal pressure is set to 250 kPa. (Ht / Wt) x 100(%)

[0026] The aspect ratio is more preferably 45% or more, and even more preferably 47.5% or more. It is even more preferably 50% or more, even more preferably 52.5% or more, even more preferably 55% or more, even more preferably 58% or more, and even more preferably 70% or more. There is no particular upper limit, but it is, for example, 100% or less.

[0027] 2. Tire shape In the tire according to the present disclosure, when mounted on a regular rim and the internal pressure is set to 250 kPa, the specific outer diameter Dt (mm) is, for example, preferably 515 mm or more, more preferably 558 mm or more, even more 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 802 mm or less, even more preferably less than 725 mm, even more preferably 719 mm or less, even more preferably less than 707 mm, even more preferably 700 mm or less, and particularly preferably less than 685 mm.

[0028] The specific cross-sectional width Wt (mm) is, for example, 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 or more, and most preferably 193 mm or more. On the other hand, it is preferably less than 305 mm, more preferably 255 mm or less, even more preferably less than 245 mm, even more preferably less than 210 mm, even more preferably 205 mm or less, particularly preferably less than 205 mm, and most preferably less than 200 mm.

[0029] The specific cross-sectional height Ht (mm) is, for example, preferably 37 mm or more, more preferably 87 mm or more, and even more preferably 95 mm or more, while it is preferably less than 180 mm, more preferably 147 mm or less, even more preferably 144 mm or less, even more preferably less than 112 mm, even more preferably 109 mm or less, and even more preferably less than 101 mm.

[0030] In the present disclosure, when considering the stability of ride comfort during running, (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, when considering 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 508 (mm) or less.

[0031] In addition, the virtual volume V (mm) of the space occupied by the tire when it is mounted on a standard rim and the internal pressure is set to 250 kPa. 3 ) can be calculated using the following formula based on the cross-sectional width Wt (mm), outer diameter Dt (mm), and cross-sectional height Ht (mm). V=[(Dt / 2) 2 -{(Dt / 2)-Ht} 2 ]×π×Wt

[0032] A specific virtual volume V is, for example, 13,000,000 mm 3 It is preferable that the length is 29,000,000 mm or more. 3 More preferably, it is 31,230,020 mm or more. 3 More preferably, it is 36,000,000 mm or more. 3 More preferably, it is 88,000,000 mm or more. 3 Preferably less than 77,134,503 mm 3 It is more preferable that it is 66,000,000 mm or less. 3 Less than 53,167,961 mm is preferable. 3 It is more preferable that it is equal to or less than 44,000,000 mm 3 It is more preferable that the thickness is less than 38,800,000 mm 3 It is particularly preferred that it is less than 10 ...

[0033] In addition, in the present disclosure, the virtual volume V (mm3 ) and cross-sectional width Wt (mm) are [(V+1.5×10 7 ) / Wt]≦4.02×10 5 It is preferable that [(V+1.5×10 7 ) / Wt] is 3.62 × 10 5 It is more preferable that it is less than 3.33 × 10 5 It is more preferable that it is 2.99 × 10 or less. 5 It is more preferable that the ratio is less than or equal to:

[0034] In this way, by reducing the virtual volume V of the tire in accordance with the reduction in the cross-sectional width Wt of the tire and reducing the volume of the tire itself, it is possible to reduce the rate of growth of the outer diameter due to centrifugal force, thereby reducing the amount of deformation in the bead portion of the side and also suppressing rounding of the tread portion.

[0035] In this case, [(V+2.0×10 7 ) / Wt]≦4.02×10 5 It is more preferable that [(V+2.5×10 7 ) / Wt]≦4.02×10 5 It is even more preferable that:

[0036] In addition, [(V+2.0×10 7 ) / Wt] is 3.81 x 10 5 It is preferable that the value is less than 3.57 × 10 5 It is more preferable that it is less than 3.31 × 10 5 It is more preferable that the value is [(V+2.5×10 7 ) / Wt] is 4.01 x 10 5 Preferably, it is 3.82 x 10 or less. 5 It is more preferable that it is less than 3.63 × 10 5 It is more preferable that the ratio is less than or equal to:

[0037] [3] Embodiments of the present disclosure Hereinafter, the present disclosure will be specifically described based on embodiments.

[0038] 1. Tread rubber composition In this embodiment, the tread rubber composition can be obtained from the rubber component, resin component, and other compounding materials described below.

[0039] (1) Rubber component In the present embodiment, as described above, the tread rubber composition contains SBR and isoprene-based rubber as rubber components. The total content of SBR and isoprene-based rubber per 100 parts by mass of the rubber component is preferably 60 parts by mass or more, and among this, the amount of SBR is preferably more than 50 parts by mass and 80 parts by mass or less.

[0040] (a) Styrene butadiene rubber (SBR) As the styrene-butadiene rubber, SBR having a weight-average molecular weight of, for example, 100,000 or more and 2,000,000 or less is preferably used, which can improve the strength of the SBR phase against strain and stress, thereby improving the breaking strength of the tire.

[0041] 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. This makes it possible to suppress aggregation of styrene units in the rubber composition, thereby improving tread conformability. The amount of vinyl bonds (amount of 1,2-bonded butadiene units) in the butadiene portion of the SBR is preferably 40% by mass or less. The structure of the SBR (measurement of the styrene amount and vinyl bond amount) can be performed using, for example, a JNM-ECA series device manufactured by JEOL Ltd.

[0042] The SBR is not particularly limited, and examples thereof include emulsion-polymerized styrene-butadiene rubber (E-SBR) and solution-polymerized styrene-butadiene rubber (S-SBR). The SBR may be either unmodified or modified, but modified S-SBR is preferred because it improves dispersibility and is expected to further improve abrasion resistance and slip resistance.

[0043] The modified SBR may be any SBR having a functional group that interacts with a filler such as silica, and examples thereof include terminal-modified SBR in which at least one terminal of the SBR has been modified with a compound (modifier) ​​having the above functional group (terminal-modified SBR having the above functional group at the terminal), main-chain-modified SBR in which the main chain has the above functional group, main-chain terminal-modified SBR in which the main chain and terminals have the above functional group (for example, main-chain terminal-modified SBR in which the main chain has the above functional group and at least one terminal has been modified with the above modifier), and terminal-modified SBR in which the SBR has been modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and in which a hydroxyl group or epoxy group has been introduced.

[0044] Examples of the functional group include an amino group, an amide group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a urea group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a sulfide group, a disulfide group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imide group, a hydrazo group, an azo group, a diazo group, a carboxyl group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group, an epoxy group, etc. These functional groups may have a substituent.

[0045] Furthermore, as the modified SBR, for example, SBR modified with a compound (modifying agent) represented by the following formula can be used.

[0046] [ka]

[0047] In the formula, R 1, R 2 and R 3 R may be the same or different and represent an alkyl group, an alkoxy group, a silyloxy group, an acetal group, a carboxyl group (-COOH), a mercapto group (-SH), or a derivative thereof. 4 and R 5 are the same or different and represent a hydrogen atom or an alkyl group. 4 and R 5 may bond to form a ring structure together with the nitrogen atom, and n represents an integer.

[0048] As the modified SBR modified with a compound (modifier) ​​represented by the above formula, SBR in which the polymerization terminals (active terminals) of solution-polymerized styrene-butadiene rubber (S-SBR) have been modified with a compound represented by the above formula (such as the modified SBR described in JP 2010-111753 A).

[0049] R 1 , R 2 and R 3 R is preferably an alkoxy group (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably an alkoxy group having 1 to 4 carbon atoms). 4 and R 5 is preferably an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms). n is preferably 1 to 5, more preferably 2 to 4, and even more preferably 3. In addition, R 4 and R 5 When the groups bond to form a ring structure together with the nitrogen atom, the ring is preferably a 4- to 8-membered ring. The alkoxy group also includes a cycloalkoxy group (such as a cyclohexyloxy group) and an aryloxy group (such as a phenoxy group or a benzyloxy group).

[0050] Specific examples of the modifying agent include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, 3-diethylaminopropyltriethoxysilane, etc. These may be used alone or in combination of two or more.

[0051] Modified SBR may also be modified with the following compounds (modifiers): Examples of the modifier include polyglycidyl ethers of polyhydric alcohols such as ethylene glycol diglycidyl ether, glycerin triglycidyl ether, trimethylolethane triglycidyl ether, and trimethylolpropane triglycidyl ether; polyglycidyl ethers of aromatic compounds having two or more phenol groups, such as diglycidylated bisphenol A; polyepoxy compounds such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxidized liquid polybutadiene; epoxy group-containing tertiary amines such as 4,4'-diglycidyl-diphenylmethylamine and 4,4'-diglycidyl-dibenzylmethylamine; diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline; Diglycidyl amino compounds such as diglycidyl orthotoluidine, tetraglycidyl meta-xylenediamine, tetraglycidyl aminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidyl aminomethylcyclohexane, and tetraglycidyl-1,3-bisaminomethylcyclohexane; amino group-containing acid chlorides such as bis-(1-methylpropyl)carbamic acid chloride, 4-morpholinecarbonyl chloride, 1-pyrrolidinecarbonyl chloride, N,N-dimethylcarbamic acid chloride, and N,N-diethylcarbamic acid chloride; epoxy group-containing silane compounds such as 1,3-bis-(glycidyloxypropyl)-tetramethyldisiloxane and (3-glycidyloxypropyl)-pentamethyldisiloxane;(Trimethylsilyl)[3-(trimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(triethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(trippropoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(tributoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldiethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldipropoxy sulfide group-containing silane compounds such as (trimethylsilyl)[3-(methyldibutoxysilyl)propyl] sulfide and (trimethylsilyl)[3-(methyldibutoxysilyl)propyl] sulfide; N-substituted aziridine compounds such as ethyleneimine and propyleneimine; methyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, Alkoxysilanes such as thyltriethoxysilane; (thio)benzophenone compounds having an amino group and / or a substituted amino group such as 4-N,N-dimethylaminobenzophenone, 4-N,N-di-t-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; 4-N,N- Benzaldehyde compounds having an amino group and / or a substituted amino group, such as dimethylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde, and 4-N,N-divinylaminobenzaldehyde; N-substituted pyrrolidones, such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, Nt-butyl-2-pyrrolidone, and N-methyl-5-methyl-2-pyrrolidone; N-substituted piperidones, such as N-methyl-2-piperidone, N-vinyl-2-piperidone, and N-phenyl-2-piperidone;N-substituted lactams such as N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-laurylolactam, N-vinyl-ω-laurylolactam, N-methyl-β-propiolactam, and N-phenyl-β-propiolactam, as well as N,N-bis-(2,3-epoxypropoxy)-aniline, 4,4-methylene-bis-(N,N-glycidylaniline), and tris-(2,3-epoxypropyl)-1,3,5-triazine-2,4,6-trione , N,N-diethylacetamide, N-methylmaleimide, N,N-diethylurea, 1,3-dimethylethyleneurea, 1,3-divinylethyleneurea, 1,3-diethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 4-N,N-dimethylaminoacetophen, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-propanone, 1,7-bis(methylethylamino)-4-heptanone, etc. Modification with the above compounds (modifiers) can be carried out by known methods.

[0052] Examples of SBR that can be used include SBR manufactured and sold by Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, Zeon Corporation, Versalis, etc. SBR may be used alone or in combination of two or more types. When two or more types of SBR are used in combination, the weight average of each SBR is used for the above-mentioned styrene amount, vinyl bond amount, etc.

[0053] (b) Isoprene rubber Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR, and among these, NR is preferably used.

[0054] Specific examples of NR include SIR20, RSS#3, and TSR20, which are commonly used in the tire industry. IR is not particularly limited, and examples of IR include IR2200, which is commonly used in the tire industry. Modified NR includes deproteinized natural rubber (DPNR) and highly purified natural rubber (UPNR). Modified NR includes epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Modified IR includes epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used alone or in combination of two or more.

[0055] (c) Butadiene rubber The tread rubber composition may further contain butadiene rubber (BR) as a rubber component, as needed. When BR is contained, the content of BR in 100 parts by mass of the rubber component is, for example, 40 parts by mass or less. The weight average molecular weight of the BR is, for example, 100,000 or more and 2,000,000 or less. The vinyl bond amount of the BR is, for example, 1% by mass or more and 30% by mass or less. The cis content of the BR is, for example, 1% by mass or more and 98% by mass or less. The trans content of the BR is, for example, 1% by mass or more and 60% by mass or less.

[0056] The BR is not particularly limited, and can be a BR with a high cis content (cis content of 90% or more), a BR with a low cis content, or a BR containing syndiotactic polybutadiene crystals. The BR can be either unmodified or modified, and examples of modified BR include modified BRs into which the above-mentioned functional groups have been introduced. These can be used alone or in combination of two or more. The cis content can be measured by infrared absorption spectroscopy.

[0057] As the BR, for example, products from Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Corporation, etc. can be used.

[0058] (d) Other rubber components Furthermore, as other rubber components, rubbers (polymers) that are generally used in the production of tires, such as nitrile rubber (NBR), may be included as necessary.

[0059] (2) Compounding materials other than rubber components (a) Resin component In this embodiment, the tread rubber composition contains a resin component from the viewpoint of imparting tackiness. As described above, the content is more than 25 parts by mass per 100 parts by mass of the rubber component, and the ratio (Q / Wt) of Q (parts by mass) to the cross-sectional width Wt (mm) is an amount (parts by mass) that exceeds 0.1. Q (parts by mass) is more preferably more than 30 parts by mass, and even more preferably more than 40 parts by mass. As described above, (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. Note that these resin components are thermoplastic, and therefore function as a softener together with the oil described below.

[0060] The resin component may be solid or liquid at room temperature. Specific examples of the resin component include rosin-based resins, styrene-based resins, coumarone-based resins, terpene-based resins, C5 resins, C9 resins, C5C9 resins, and acrylic resins, and two or more of these may be used in combination.

[0061] Rosin-based resins are resins whose main component is rosin acid obtained by processing pine resin. These rosin-based resins (rosins) can be classified based on whether they are modified or not, and can be divided into unmodified rosin (unmodified rosin) and modified rosin (rosin derivatives). Examples of unmodified rosins include tall rosin (also known as tall oil rosin), gum rosin, wood rosin, disproportionated rosin, polymerized rosin, hydrogenated rosin, and other chemically modified rosins. Modified rosin is a modified form of unmodified rosin, and examples include rosin esters, unsaturated carboxylic acid-modified rosin esters, unsaturated carboxylic acid-modified rosin amide compounds, and amine salts of rosin.

[0062] Styrenic resins are polymers that use styrene monomers as constituent monomers, and examples thereof include polymers obtained by polymerizing styrene monomers as the main component (50% by mass or more).Specific examples 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 of styrene monomers and other monomers that can be copolymerized with them.

[0063] Examples of the other monomers include acrylonitriles such as acrylonitrile and methacrylonitrile, unsaturated carboxylic acids such as acrylics and methacrylic acid, unsaturated carboxylic acid esters such as methyl acrylate and methyl methacrylate, dienes such as chloroprene and butadiene isoprene, olefins such as 1-butene and 1-pentene, α,β-unsaturated carboxylic acids such as maleic anhydride or acid anhydrides thereof, and the like.

[0064] Among the coumarone resins, coumarone-indene resins are preferred. Coumarone-indene resins are resins containing coumarone and indene as monomer components that constitute the resin skeleton (main chain). Monomer components contained in the skeleton other than coumarone and indene include styrene, α-methylstyrene, methylindene, vinyltoluene, etc.

[0065] The amount of the coumarone-indene resin per 100 parts by mass of the rubber component is, for example, more than 1.0 part by mass and less than 50.0 parts by mass.

[0066] The hydroxyl value (OH value) of the coumarone-indene resin is, for example, more than 15 mgKOH / g and less than 150 mgKOH / g. The OH value is the amount of potassium hydroxide, expressed in milligrams, required to neutralize acetic acid bonded to hydroxyl groups when acetylating 1 g of the resin, and is a value measured by potentiometric titration (JIS K 0070:1992).

[0067] The softening point of the coumarone-indene resin is, for example, more than 30° C. and less than 160° C. The softening point is the temperature at which the ball drops when the softening point specified in JIS K 6220-1:2001 is measured using a ring and ball softening point tester.

[0068] Terpene resins include polyterpenes, terpene phenols, and aromatic modified terpene resins. Polyterpenes are resins obtained by polymerizing terpene compounds and their hydrogenated products. Terpene compounds are (C5H8) n The hydrocarbons and their oxygen-containing derivatives are represented by the following composition: monoterpenes (C 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32), and examples thereof include α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, and γ-terpineol.

[0069] Examples of polyterpenes include terpene resins such as α-pinene resin, β-pinene resin, limonene resin, dipentene resin, and β-pinene / limonene resin, which are made from the above-mentioned terpene compounds, as well as hydrogenated terpene resins obtained by hydrogenating the terpene resins. Examples of terpene phenols include resins obtained by copolymerizing the above-mentioned terpene compounds with phenolic compounds, and resins obtained by hydrogenating the above-mentioned resins. Specific examples include resins obtained by condensing the above-mentioned terpene compounds, phenolic compounds, and formalin. Examples of phenolic compounds include phenol, bisphenol A, cresol, and xylenol. Examples of aromatic-modified terpene resins include resins obtained by modifying terpene resins with aromatic compounds, and resins obtained by hydrogenating the above-mentioned resins. The aromatic compound is not particularly limited as long as it is a compound having an aromatic ring, and examples thereof include phenolic compounds such as phenol, alkylphenol, alkoxyphenol, and unsaturated hydrocarbon group-containing phenol; naphthol compounds such as naphthol, alkylnaphthol, alkoxynaphthol, and unsaturated hydrocarbon group-containing naphthol; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, and unsaturated hydrocarbon group-containing styrene; coumarone, indene, and the like.

[0070] As commercially available terpene resins, for example, products from Yasuhara Chemical Co., Ltd. can be used, and they may be used alone or in combination of two or more kinds.

[0071] "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 preferably used as a C5 petroleum resin.

[0072] "C9 resin" refers to a resin obtained by polymerizing a C9 fraction, and may be a hydrogenated or modified version. Examples of C9 fractions include petroleum fractions having 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, and methylindene. Specific examples of suitable aromatic vinyl resins include coumarone-indene resins, coumarone resins, indene resins, and aromatic vinyl resins. Preferred aromatic vinyl resins are homopolymers of α-methylstyrene or styrene, or copolymers of α-methylstyrene and styrene, with copolymers of α-methylstyrene and styrene being more preferred, due to their economical efficiency, ease of processing, and excellent heat generation properties. Examples of aromatic vinyl resins that can be used include those commercially available from Kraton, Eastman Chemical Company, and the like.

[0073] "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be a hydrogenated or modified resin. Examples of C5 fractions and C9 fractions include the petroleum fractions mentioned above. As the C5C9 resin, for example, commercially available products from Tosoh Corporation, LUHUA, etc. can be used.

[0074] The acrylic resin is not particularly limited, but for example, a solventless acrylic resin can be used.

[0075] Examples of solvent-free acrylic resins include (meth)acrylic resins (polymers) synthesized by high-temperature continuous polymerization (high-temperature continuous bulk polymerization) (methods described in U.S. Pat. No. 4,414,370, JP-A-59-6207, JP-B-5-58005, JP-A-1-313522, U.S. Pat. No. 5,010,166, and Toa Gosei Kenkyusho TREND 2000 Vol. 3, pp. 42-45, etc.), with minimal use of secondary raw materials such as polymerization initiators, chain transfer agents, and organic solvents. In this disclosure, (meth)acrylic refers to both methacrylic and acrylic.

[0076] Examples of the monomer components constituting the acrylic resin include (meth)acrylic acid, (meth)acrylic acid esters (alkyl esters, aryl esters, aralkyl esters, etc.), (meth)acrylamide, and (meth)acrylic acid derivatives such as (meth)acrylamide derivatives.

[0077] Furthermore, aromatic vinyls such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, and divinylnaphthalene may be used together with (meth)acrylic acid or a (meth)acrylic acid derivative as a monomer component constituting the acrylic resin.

[0078] The acrylic resin may be a resin composed solely of a (meth)acrylic component, or a resin containing components other than a (meth)acrylic component, and may have a hydroxyl group, a carboxyl group, a silanol group, or the like.

[0079] As the resin component, for example, products from Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Company, Nitto Chemical Co., Ltd., Nippon Shokubai Co., Ltd., JX Nippon Energy Corporation, Arakawa Chemical Industries, Ltd., Taoka Chemical Co., Ltd., etc. can be used.

[0080] (b) Filler In this embodiment, the rubber composition preferably contains a filler. Specific fillers include, for example, carbon black, silica, calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica. Among these, silica is preferably used as a reinforcing filler from the viewpoint of achieving low rolling resistance, and is preferably used in combination with a silane coupling agent. Furthermore, it is also preferable to use carbon black as a reinforcing filler, if necessary.

[0081] (a) Silica The content of silica per 100 parts by mass of the rubber component is preferably 40 parts by mass or more. The upper limit is not particularly limited as long as the rubber composition can be kneaded, but is preferably, for example, about 200 parts by mass. This allows the silica to be dispersed throughout the rubber system without being unevenly distributed in either NR or SBR, thereby improving abrasion resistance and slip resistance.

[0082] As silica, it has a BET specific surface area of ​​180m 2 / g or more, 300m 2 / g or less of silica can be preferably used. This further enhances the reinforcing properties of silica, thereby improving wear resistance in particular. The BET specific surface area is the nitrogen adsorption specific surface area (N2SA) value measured by the BET method in accordance with ASTM D3037-93.

[0083] Specific examples of silica include dry process silica (anhydrous silica), wet process silica (hydrated silica), etc. Among these, wet process silica is preferred because it has a large number of silanol groups, and products available from, for example, Evonik, Degussa, Rhodia, Tosoh Silica Corporation, Solvay Japan, Tokuyama Corporation, etc. can be used.

[0084] (b) Silane coupling agent The rubber composition preferably contains a silane coupling agent together with silica. The silane coupling agent is not particularly limited, and examples thereof include 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)disulfide, bis(4-triethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocathanide, Examples of suitable silanes include sulfide-based silanes such as rubamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based silanes such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and Momentive's NXT and NXT-Z; vinyl-based silanes such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based silanes such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based silanes such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based silanes such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based silanes such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. These silanes may be used alone or in combination of two or more.

[0085] The amount of the silane coupling agent is preferably more than 3 parts by mass and less than 15 parts by mass relative to 100 parts by mass of silica. Specific examples of the silane coupling agent include products from Degussa, Momentive, Shin-Etsu Silicones, Tokyo Chemical Industry, Azmax, and Dow Corning Toray.

[0086] (c) Carbon black The tread rubber composition preferably contains carbon black. The amount of carbon black is, for example, 1 part by mass or more and 200 parts by mass or less per 100 parts by mass of the rubber component.

[0087] The carbon black is not particularly limited, and examples thereof include furnace blacks (furnace carbon black) such as SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF, and ECF; acetylene black (acetylene carbon black); thermal blacks (thermal carbon black) such as FT and MT; and channel blacks (channel carbon black) such as EPC, MPC, and CC. These may be used alone or in combination of two or more.

[0088] The nitrogen adsorption specific surface area (N2SA) of carbon black is, for example, 30m 2 / g or more, 250m 2 The carbon black has a dibutyl phthalate (DBP) absorption of, for example, 50 ml / 100 g or more and 250 ml / 100 g or less. The nitrogen adsorption specific surface area of ​​carbon black is measured in accordance with ASTM D4820-93, and the DBP absorption is measured in accordance with ASTM D2414-93.

[0089] Specific carbon blacks are not particularly limited, and examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available carbon blacks include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin-Nichika Carbon Co., Ltd., and Columbia Carbon Co., Ltd. These may be used alone or in combination of two or more.

[0090] (d) Other fillers In addition to the above-mentioned 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, mica, etc. The content of these fillers is, for example, more than 0.1 part by mass and less than 200 parts by mass per 100 parts by mass of the rubber component.

[0091] (c) Softener The tread rubber composition may contain oil (including extender oil), liquid rubber, etc. as a softener. The total content of these is preferably more than 1 part by mass and less than 10 parts by mass per 100 parts by mass of the rubber component. The oil content includes the amount of oil contained in the rubber (oil-extended rubber).

[0092] Examples of oils include mineral oils (commonly referred to as process oils), vegetable oils, and mixtures thereof. Examples of mineral oils (process oils) that can be used include paraffin-based process oils, aromatic process oils, and naphthenic process oils. Examples of vegetable oils 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, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. These may be used alone or in combination of two or more.

[0093] Specific examples of process oils (mineral oils) that can be used include products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., Japan Energy Co., Ltd., Orisoi Co., Ltd., H&R Co., Ltd., Toyokuni Oil Mills Co., Ltd., Showa Shell Sekiyu K.K., Fuji Kosan Co., Ltd., and the like.

[0094] The liquid rubbers mentioned as softeners are polymers that are in a liquid state at room temperature (25°C) and contain the same monomers as solid rubbers. Examples of liquid rubbers include farnesene-based polymers, liquid diene-based polymers, and hydrogenated products thereof.

[0095] Farnesene polymers are polymers obtained by polymerizing farnesene, which has structural units based on farnesene. Farnesene has isomers such as α-farnesene ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodecatetraene) and β-farnesene (7,11-dimethyl-3-methylene-1,6,10-dodecatriene).

[0096] The farnesene-based polymer may be a homopolymer of farnesene (farnesene homopolymer) or a copolymer of farnesene and a vinyl monomer (farnesene-vinyl monomer copolymer).

[0097] 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).

[0098] The liquid diene polymer has a weight average molecular weight (Mw) of, for example, 1.0 × 10 in terms of polystyrene measured by gel permeation chromatography (GPC). 3 Super, 2.0×10 5 In this specification, the Mw of the liquid diene polymer is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

[0099] The amount of the liquid rubber (total amount of the liquid farnesene polymer, liquid diene polymer, etc.) is, for example, more than 1 part by mass and less than 100 parts by mass per 100 parts by mass of the rubber component.

[0100] As the liquid rubber, for example, products of Kuraray Co., Ltd., Cray Valley Co., Ltd., etc. can be used.

[0101] (d) Antioxidants The tread rubber composition preferably contains an antioxidant. The content of the antioxidant is, for example, 1 part by mass or more and 10 parts by mass or less per 100 parts by mass of the rubber component.

[0102] Examples of the antioxidant include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, and N,N'-di-2-naphthyl-p-phenylenediamine. Examples of antioxidants include p-phenylenediamine antioxidants such as quinolone; quinoline antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. These antioxidants may be used alone or in combination of two or more.

[0103] As the antioxidant, for example, products available from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., Flexis, etc. can be used.

[0104] (e) stearic acid The tread rubber composition may contain stearic acid. The content of stearic acid is, for example, 0.5 parts by mass or more and 10.0 parts by mass or less per 100 parts by mass of the rubber component. As the stearic acid, a conventionally known stearic acid can be used, for example, products from NOF Corporation, NOF Corporation, Kao Corporation, FUJIFILM Wako Pure Chemical Industries, Ltd., Chiba Fatty Acid Co., Ltd., etc. can be used.

[0105] (f) zinc oxide The tread rubber composition may contain zinc oxide (zinc white). The content of zinc oxide is, for example, 0.5 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the rubber component. As the zinc oxide, a conventionally known product can be used, for example, products from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc.

[0106] (g) Wax The tread rubber composition preferably contains wax. The wax content is, for example, 0.5 to 20 parts by mass, preferably 1.0 to 15 parts by mass, and more preferably 1.5 to 10 parts by mass per 100 parts by mass of the rubber component.

[0107] The wax is not particularly limited, and examples thereof include petroleum waxes such as paraffin wax and microcrystalline wax; natural waxes such as vegetable wax and animal wax; and synthetic waxes such as polymers of ethylene, propylene, etc. These may be used alone or in combination of two or more.

[0108] As the wax, for example, products from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Seiko Chemical Co., Ltd., etc. can be used.

[0109] (h) Crosslinking agents and vulcanization accelerators The tread rubber composition preferably contains a crosslinking agent such as sulfur, etc. The content of the crosslinking agent is, for example, 0.1 parts by mass or more and 10.0 parts by mass or less per 100 parts by mass of the rubber component.

[0110] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, soluble sulfur, etc., which are commonly used in the rubber industry. These may be used alone or in combination of two or more.

[0111] As sulfur, for example, products from Tsurumi Chemical Industry Co., Ltd., Karuizawa Iso Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanzuri Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc. can be used.

[0112] Examples of crosslinking agents other than sulfur include vulcanizing agents containing sulfur atoms, such as Tackirol V200 manufactured by Taoka Chemical Co., Ltd., DURALINK HTS (sodium 1,6-hexamethylenedithiosulfate dihydrate) manufactured by Flexsys, and KA9188 (1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane) manufactured by Lanxess, as well as organic peroxides such as dicumyl peroxide.

[0113] The tread rubber composition preferably contains a vulcanization accelerator. The content of the vulcanization accelerator is, for example, 0.3 parts by mass or more and 10.0 parts by mass or less per 100 parts by mass of the rubber component.

[0114] Examples of the vulcanization accelerator include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiazyl sulfenamide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazole sulfenamide, Nt-butyl-2-benzothiazolyl sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, N-oxyethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators such as diphenyl guanidine, di-orthotolyl guanidine, and orthotolyl biguanidine. These may be used alone or in combination of two or more.

[0115] (i) Other In addition to the above components, the tread rubber composition may further contain additives commonly used in the tire industry, such as fatty acid metal salts, carboxylic acid metal salts, organic peroxides, graphite, etc. The content of these additives is, for example, more than 0.1 parts by mass and less than 200 parts by mass per 100 parts by mass of the rubber component.

[0116] 2. Preparation of tread rubber composition The tread rubber composition is produced by a general method, for example, a manufacturing method including a base kneading step in which a rubber component and a filler such as silica or carbon black are kneaded together, and a finish kneading step in which the kneaded product obtained in the base kneading step is kneaded together with a crosslinking agent.

[0117] The kneading can be carried out using a known (internal) kneading machine such as a Banbury mixer, a kneader, or an open roll.

[0118] The kneading temperature in the base kneading step is, for example, 50° C. or higher and 200° C. or lower, and the kneading time is, for example, 30 seconds or higher and 30 minutes or lower. In the base kneading step, in addition to the above components, compounding agents conventionally used in the rubber industry, for example, softeners such as oil, stearic acid, zinc oxide, antioxidants, waxes, vulcanization accelerators, etc., may be appropriately added and kneaded as needed.

[0119] In the final kneading step, the kneaded product obtained in the base kneading step is kneaded with a crosslinking agent. The kneading temperature in the final kneading step is, for example, room temperature or higher and 80°C or lower, and the kneading time is, for example, 1 minute or longer and 15 minutes or shorter. In the final kneading step, in addition to the above components, a vulcanization accelerator, zinc oxide, etc. may be appropriately added and kneaded as necessary.

[0120] 3. Tire manufacturing The tire of the present disclosure is manufactured by a conventional method using the unvulcanized rubber composition obtained through the above-mentioned finish mixing step. That is, the unvulcanized rubber composition is extruded to match the shape of each tire component of the tread, and then molded together with other tire components by a conventional method on a tire building machine to produce an unvulcanized tire.

[0121] Specifically, an inner liner as a component for ensuring the airtightness of the tire, a carcass as a component for withstanding the load, impact, and inflation pressure to which the tire is subjected, and a belt as a component for tightly fastening the carcass and increasing the rigidity of the tread are wound around a forming drum, and both ends of the carcass are fixed to both side edges, and bead portions as components for fixing the tire to the rim are arranged. After forming into a toroidal shape, a tread is attached to the center of the outer periphery, and sidewall portions as components for protecting the carcass and withstanding bending are attached to the radially outer side, thereby producing an unvulcanized tire.

[0122] In this embodiment, it is preferable to provide an inclined belt layer extending at an angle of 55° or more and 75° or less with respect to the tire circumferential direction as the belt, thereby ensuring the durability of the tire and sufficiently maintaining the rigidity of the tread.

[0123] The unvulcanized tire is then heated and pressurized in a vulcanizer to obtain a tire. The vulcanization process can be carried out by using a known vulcanization method. The vulcanization temperature is, for example, 120°C or higher and 200°C or lower, and the vulcanization time is, for example, 5 minutes or higher and 15 minutes or lower.

[0124] At this time, the tire is molded into a shape that satisfies the above-mentioned (Equation 1).

[0125] Specific tires that can satisfy the above (Equation 1) include tires with size notations such as 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.

[0126] In the present embodiment, among the tires that can satisfy (Formula 1), it is preferable to apply it to a pneumatic tire for a passenger car, and by forming a tread portion using the above-mentioned tread rubber composition and giving it a shape that satisfies (Formula 1), it can more suitably contribute to solving the problem in the present disclosure, which is to improve steering stability when driving in rainy weather.

[0127] The term "passenger car pneumatic tires" refers to tires mounted on four-wheeled vehicles with a maximum load capacity of 1,000 kg or less. Here, "maximum load capacity" refers to the maximum load capacity determined for each tire by the standard system, including the standard on which the tire is based. For example, the maximum load capacity is determined based on the load index (LI) in the case of the Japan Automobile Tire Manufacturers Association (JATMA) standard, the maximum value listed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURE" in the case of the Tire and Rim Association, Inc. (TRA), and the "INFLATION PRESSURE" in the case of ETRTO. For tires not specified in these standards, the maximum load capacity is calculated using the following formula: Maximum load capacity (kg)=0.000011×V+175 V: Virtual volume of the tire (mm 3 )

[0128] The maximum load capacity is not particularly limited as long as it is 1000 kg or less, but generally, as the maximum load capacity increases, the tire weight tends to increase, and accordingly the braking distance becomes longer due to inertia. Therefore, it is preferably 900 kg or less, more preferably 800 kg or less, and even more preferably 700 kg or less.

[0129] From the viewpoint of the braking distance due to inertia described above, 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, or 8 kg or less. The tire of the present disclosure may be equipped with electronic components. In this case, the tire weight referred to here includes the weight of the electronic components and the electronic component mounting members. Furthermore, if a sealant, sponge, or the like is provided in the inner cavity, the tire weight also includes these. [Example]

[0130] Hereinafter, the present disclosure will be described more specifically with reference to examples.

[0131] 1. Production of rubber composition for tread First, a rubber composition for a tread was produced.

[0132] (1) Compounding materials First, the following ingredients were prepared.

[0133] (a) Rubber component (i) NR:RSS#3 (b) SBR: NS116 manufactured by JSR Corporation (styrene content: 20% by mass) (c) BR: UBEPOL BR150B manufactured by Ube Industries, Ltd.

[0134] (b) Compounding materials other than rubber components (a) Carbon black: Show Black N220 manufactured by Cabot Japan Co., Ltd. (N2SA:111m 2 / g, DBP: 115ml / 100g) (b) Silica: Ultrasil VN3 manufactured by Degussa (N2SA:175m 2 / g) (c) Silane coupling agent: Si69 manufactured by Degussa (Bis 3-triethoxysilylpropyl) tetrasulfide) (d) Process oil: Process X-140 manufactured by Japan Energy Corporation (Aroma oil) (e) Resin component: Sylvatraxx 4401 manufactured by Kraton (copolymer of α-methylstyrene and styrene) (f) Zinc oxide: Two types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. (g) Stearic acid: NOF Corporation's "Tsubaki" stearic acid (H) Anti-aging agent: Nocrac 6C manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine) (i) Wax: Sunnock Wax manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (10) Crosslinking agents and vulcanization accelerators Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. Vulcanization accelerator 1: Noccela CZ manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (N-cyclohexyl-2-benzothiazolylsulfenamide) Vulcanization accelerator 2: Noccela D manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (N,N'-diphenylguanidine)

[0135] (2) Production of rubber compositions The blending amounts (parts by mass) of each blending material excluding the resin component are shown in Table 1. The blending amounts (parts by mass) of the resin component were as shown in Tables 2 to 4.

[0136] [Table 1]

[0137] Of the compounding materials shown in Table 1, the compounding materials excluding sulfur, vulcanization accelerator-1, and vulcanization accelerator-2, and the resin component were kneaded at 150°C for 5 minutes to obtain a kneaded mixture.

[0138] 2. Tire manufacturing Next, sulfur and a vulcanization accelerator were added to the obtained kneaded product, and the mixture was kneaded using an open roll for 5 minutes at 80°C to obtain a tread rubber composition. A tread was molded using the obtained tread rubber composition, and the tread was laminated together with other tire components to form an unvulcanized tire, which was then press-vulcanized for 10 minutes at 170°C to produce test tires of sizes 155 type (Table 2), 205 type (Table 3), and 245 type (Table 4).

[0139] Then, the cross-sectional width Wt (mm), outer diameter Dt (mm), cross-sectional height Ht (mm), and aspect ratio (%) of each test tire were calculated, and the virtual volume V (mm 3 ) was sought.

[0140] And (Dt-2×Ht), (V+1.5×10 7 ) / Wt, (V+2.0×107 ) / Wt, (V+2.5×10 7 ) / Wt and Q / Wt were calculated. The results are shown in Tables 2 to 4.

[0141] 3. Evaluation of handling stability (1) Test method Each test tire was fitted to all wheels of a vehicle (a domestically produced FF vehicle with an engine displacement of 2000cc) and inflated to an internal pressure of 250kPa. The vehicle was then driven on a test course on a wet road surface at speeds of 40km / h and 120km / h, and the drivers evaluated the change in handling due to the change in driving speed on a five-point scale from 1 (a significant change felt) to 5 (almost no change felt). The total score of the evaluations by the 20 drivers was then calculated.

[0142] Next, the results for the standard tires (Comparative Example 1-2 in Table 2, Comparative Example 2-2 in Table 3, and Comparative Example 3-3 in Table 4) were set to 100, and indexed according to the following formula to obtain the wet steering stability index. A larger value indicates better steering stability when traveling at high speeds on wet roads. Wet steering stability index = [(Test tire results) / (Evaluation standard tire results)] x 100

[0143] (2) Evaluation results Table 2 shows the evaluation results for the size 155 type, Table 3 shows the evaluation results for the size 205 type, and Table 4 shows the evaluation results for the size 245 type.

[0144] [Table 2]

[0145] [Table 3]

[0146] [Table 4]

[0147] From Tables 2 to 4, it can be seen that for all sizes of tires, 155, 205, and 245, when the resin component amount Q is 1 / 4 of the rubber component amount, i.e., more than 25 parts by mass per 100 parts by mass of the rubber component, and the above-mentioned (Equation 1) and (Equation 2) are satisfied, the wet steering stability index exceeds 100, and a pneumatic tire with sufficiently improved steering stability when traveling at high speeds on wet roads can be provided.

[0148] Furthermore, by satisfying the requirements specified in this disclosure (2) and subsequent sections, it is possible to provide a pneumatic tire with a higher wet steering stability index and further improved steering stability when traveling at high speeds on wet roads.

[0149] On the other hand, when the resin component amount Q is 1 / 4 or less of the rubber component amount (25 parts by mass or less per 100 parts by mass of the rubber component), or when either (Equation 1) or (Equation 2) is not satisfied, the wet steering stability index is 100 or less, and it can be seen that the steering stability when driving at high speeds on wet roads is not sufficiently improved.

[0150] Although the present disclosure has been described above based on the embodiments, the present disclosure is not limited to the above embodiments. Various modifications can be made to the above embodiments within the scope of the same or equivalent to the present disclosure.

[0151] This disclosure (1) The tread portion is formed of a rubber composition containing styrene-butadiene rubber and isoprene-based rubber as rubber components and also containing a resin component, The content of the resin component relative to 100 parts by mass of the rubber component is Q (parts by mass), When mounted on a standard rim and the internal pressure is 250 kPa, the tire cross-sectional width is Wt (mm) and the outer diameter is Dt (mm). a content Q (parts by mass) of the resin component relative to 100 parts by mass of the rubber component is more than 25 parts by mass, It is a pneumatic tire characterized by satisfying the following (Formula 1) and (Formula 2). 1600≦(Dt 2 ×π / 4) / Wt≦2827.4 (Formula 1) Q / Wt≧ 0.26 ···············(Formula 2)

[0152] This disclosure (2) is When the amount of styrene-butadiene rubber in 100 parts by mass of the rubber component is R1 (parts by mass) and the amount of the isoprene rubber is R2 (parts by mass), It is a pneumatic tire characterized by satisfying the following (Formula 3) and (Formula 4), and is the pneumatic tire according to the above-mentioned disclosure (1). R1+R2≧60 ················(Formula 3) 50<R1≦80 ················(Formula 4)<0000​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​The weight average molecular weight of the styrene butadiene rubber is 100,000 or more and 2,000,000 or less, and the present disclosure (1) to the present disclosure ( 5 ) and any combination of pneumatic tires.

[0158] This disclosure ( 7 )teeth, The styrene-butadiene rubber is a modified solution-polymerized styrene-butadiene rubber, and the present disclosure (1) to the present disclosure ( 6 ) and any combination of pneumatic tires.

[0159] This disclosure ( 8 )teeth, The styrene butadiene rubber has a styrene content of 5% by mass or more and 25% by mass or less, and 7 ) and any combination of pneumatic tires.

[0160] This disclosure ( 9 )teeth, The rubber composition has a styrene content of 1% by mass or more and 5% by mass or less, and 8 ) and any combination of pneumatic tires.

[0161] This disclosure ( 10 )teeth, The rubber composition further contains 40 parts by mass or less of butadiene rubber in 100 parts by mass of the rubber component, and 9 ) and any combination of pneumatic tires.

[0162] This disclosure ( 11 )teeth, The resin component is a resin component 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, and is characterized in that the present disclosure (1) to the present disclosure ( 10 ) and any combination of pneumatic tires.

[0163] This disclosure ( 12 )teeth, The rubber composition is characterized by containing 40 parts by mass or more of silica per 100 parts by mass of the rubber component, and the present disclosure (1) to the present disclosure ( 11 ) and any combination of pneumatic tires.

[0164] This disclosure ( 13 )teeth, The BET specific surface area of ​​the silica is 180 m 2 / g or more, 300m 2 / g or less, 12 ) is a pneumatic tire described in

[0165] This disclosure ( 14 )teeth, The present disclosure is characterized in that the silane coupling agent is contained in an amount of more than 3 parts by mass and less than 15 parts by mass relative to 100 parts by mass of the silica. 12 ) or this disclosure ( 13 ) is a pneumatic tire described in

[0166] This disclosure ( 15 )teeth, The flatness is 40% or more, and the present disclosure (1) to the present disclosure ( 14 ) and any combination of pneumatic tires.

[0167] This disclosure ( 16 )teeth, The outer diameter Dt (mm) is less than 843 mm, and 15 ) and any combination of pneumatic tires.

[0168] This disclosure ( 17 )teeth, The cross-sectional width Wt (mm) is less than 305 mm, and 16 ) and any combination of pneumatic tires.

[0169] This disclosure ( 18 )teeth, When the tire is mounted on a regular 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), and (Dt-2 x Ht) is 430 (mm) or more, and the present disclosure (1) to the present disclosure ( 17 ) and any combination of pneumatic tires.

[0170] This disclosure ( 19 )teeth, When the tire is mounted on a standard rim and the internal pressure is 250 kPa, the tire cross-sectional width is Wt (mm), the outer diameter is Dt (mm), and the cross-sectional height is Ht (mm). Virtual volume V (mm) of the space occupied by the tire 3 ) and Wt satisfy the following formula, and the present disclosure (1) to the present disclosure ( 18 ) and any combination of pneumatic tires. [(V+1.5×10 7 ) / Wt]≦4.02×10 5

[0171] This disclosure ( 20 )teeth, The present disclosure is characterized by satisfying the following formula: 19 ) is a pneumatic tire described in [(V+2.0×10 7 ) / Wt]≦4.02×105

[0172] This disclosure ( 21 )teeth, The present disclosure is characterized by satisfying the following formula: 20 ) is a pneumatic tire described in [(V+2.5×10 7 ) / Wt]≦4.02×10 5

[0173] This disclosure ( 22 )teeth, The present disclosure (1) to the present disclosure ( 21 ) and any combination of pneumatic tires.

Claims

1. The tread portion is formed of a rubber composition containing styrene-butadiene rubber and isoprene-based rubber as rubber components and also containing a resin component, The content of the resin component relative to 100 parts by mass of the rubber component is represented by Q (parts by mass), When the tire is mounted on a standard rim and the internal pressure is 250 kPa, the cross-sectional width is Wt (mm) and the outer diameter is Dt (mm). a content Q (parts by mass) of the resin component relative to 100 parts by mass of the rubber component is more than 25 parts by mass, A pneumatic tire characterized by satisfying the following (Equation 1) and (Equation 2): 1600≦(Dt) ２ ×π / 4) / Wt≦2827.4 (Equation 1) Q / Wt≧0.26 (Formula 2)

2. When the amount of the styrene-butadiene rubber in 100 parts by mass of the rubber component is R1 (parts by mass) and the amount of the isoprene-based rubber is R2 (parts by mass), 2. The pneumatic tire according to claim 1, wherein the following (Equation 3) and (Equation 4) are satisfied: R1+R2≧60 ・・・・・・・・・・・・・・・(Formula 3) 50<R1≦80 ・・・・・・・・・・・・・・・(Formula 4)

3. 3. The pneumatic tire according to claim 1, wherein the following formula is satisfied: 1865≦(Dt ２ ×π / 4) / Wt

4. 4. The pneumatic tire according to claim 1, wherein a content Q (parts by mass) of the resin component relative to 100 parts by mass of the rubber component is more than 30 parts by mass.

5. 5. The pneumatic tire according to claim 1, wherein the following formula (6) is satisfied: Q / Wt<0.35 (Formula 6)

6. 6. The pneumatic tire according to claim 1, wherein the styrene-butadiene rubber has a weight average molecular weight of 100,000 or more and 2,000,000 or less.

7. 7. The pneumatic tire according to claim 1, wherein the styrene-butadiene rubber is a modified solution-polymerized styrene-butadiene rubber.

8. 8. The pneumatic tire according to claim 1, wherein the styrene-butadiene rubber has a styrene content of 5% by mass or more and 25% by mass or less.

9. 9. The pneumatic tire according to claim 1, wherein the rubber composition has a styrene content of 1% by mass or more and 5% by mass or less.

10. 10. The pneumatic tire according to claim 1, wherein the rubber composition further contains 40 parts by mass or less of butadiene rubber per 100 parts by mass of the rubber component.

11. The pneumatic tire according to any one of claims 1 to 10, characterized in that the resin component is a resin component selected from the group consisting of C5-based resins, C5-C9-based resins, C9-based resins, terpene-based resins, terpene-aromatic compound-based resins, rosin-based resins, dicyclopentadiene resins, and alkylphenol-based resins.

12. 12. The pneumatic tire according to claim 1, wherein the rubber composition contains 40 parts by mass or more of silica per 100 parts by mass of the rubber component.

13. The BET specific surface area of ​​the silica is 180 m ２ / g or more, 300m ２ The pneumatic tire according to claim 12, characterized in that the tensile strength is 1 / g or less.

14. The pneumatic tire according to claim 12 or 13, wherein a silane coupling agent is contained in an amount of more than 3 parts by mass and less than 15 parts by mass per 100 parts by mass of the silica.

15. 15. The pneumatic tire according to claim 1, wherein an aspect ratio is 40% or more.

16. 16. The pneumatic tire according to claim 1, wherein the outer diameter Dt (mm) is less than 843 mm.

17. 17. The pneumatic tire according to claim 1, wherein the cross-sectional width Wt (mm) is less than 305 mm.

18. The pneumatic tire according to any one of claims 1 to 17, characterized in that, when the outer diameter of the tire is Dt (mm) and the cross-sectional height of the tire is Ht (mm) when the tire is mounted on a regular rim and the internal pressure is 250 kPa, (Dt - 2 x Ht) is 430 (mm) or more.

19. When the tire is mounted on a standard rim and the internal pressure is 250 kPa, the cross-sectional width is Wt (mm), the outer diameter is Dt (mm), and the cross-sectional height is Ht (mm). Virtual volume V (mm) of the space occupied by the tire ３ 19. The pneumatic tire according to claim 1, wherein Wt satisfies the following formula: [(V+1.5×10) ７ ) / Wt]≦4.02×� ５

20. 20. The pneumatic tire according to claim 19, wherein the following formula is satisfied: [(V+2.0×10) ７ ) / Wt]≦4.02×� ５

21. 21. The pneumatic tire according to claim 20, wherein the following formula is satisfied: [(V+2.5×10) ７ ) / Wt]≦4.02×� ５

22. The pneumatic tire according to any one of claims 1 to 21, which is a pneumatic tire for a passenger car.

Images