tire

Abstract

To provide a tire which is excellent in wet grip performance after long-term use.SOLUTION: A tire includes a tread part, wherein the rubber layer of the tread part is composed of a rubber composition containing a rubber component containing at least one rubber selected from the group consisting of styrene-butadiene rubber and isoprene-based rubber, and a copolymer resin containing styrene and cyclopentadiene as monomer components, and when maximum load capacity of the tire is represented by WL (kg), the weight of the tire is represented by G (kg) and the mass of the rubber component is 100 mass%, the total styrene amount (mass%) in the rubber composition is represented by St, WL, G and St satisfy the following expression (1) and expression (2). Expression (1): G / WL<0.0145. Expression (2): St / (G / WL)>8.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a tire.

Background Art

[0002] In recent years, improvement of the wet grip performance of tires has been desired. Patent Document 1 describes using a tire rubber composition containing a predetermined conjugated diene rubber and a conjugated diene polymer as rubber components, and further containing a predetermined amount of silica and a predetermined tetrazine compound, thereby improving the wet grip performance.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the tread rubber, due to the centrifugal force received during driving, the softening agent gradually elutes from the rubber, so there is a problem that the wet grip performance deteriorates with repeated use.

[0005] An object of the present invention is to provide a tire having excellent wet grip performance after long-term use.

Means for Solving the Problems

[0006] The present invention relates to the following tire. A tire including a tread portion, wherein the rubber layer of the tread portion is composed of a rubber composition containing a rubber component including at least one rubber selected from the group consisting of styrene-butadiene rubber and isoprene rubber, and a copolymer resin containing styrene and cyclopentadiene as monomer components. The maximum load capacity of the tire is W L (kg), the weight of the tire is G (kg), and when the mass of the rubber component is 100% by mass, when the total styrene amount (mass %) in the rubber composition is St, W L A tire in which G and St satisfy the following formulas (1) and (2). (1) G / W L <0.0145 (2) St / (G / W L )>8

Advantages of the Invention

[0007] According to the present invention, a tire excellent in wet grip performance after long-term use can be provided.

Brief Description of the Drawings

[0008]

Figure 1

Embodiments for Carrying Out the Invention

[0009] Hereinafter, a tire according to an embodiment of the present invention will be described. The tire of this embodiment is a tire provided with a tread portion, and the rubber layer of the tread portion is composed of a rubber composition containing at least one rubber selected from the group consisting of styrene-butadiene rubber and isoprene rubber, and a copolymer resin containing styrene and cyclopentadiene as monomer components. The maximum load capacity of the tire is W L (kg), the weight of the tire is G (kg), and when the mass of the rubber component is 100% by mass, when the total styrene amount (mass %) in the rubber composition is St, W L A tire in which G and St satisfy the following formulas (1) and (2). (1) G / W L <0.0145 (2) St / (G / W L )>8

[0010] Although not intended to be bound by theory, in the present invention, the following mechanisms are considered for the improvement of wet grip performance after long-term use. That is, (1) The copolymer resin containing styrene and cyclopentadiene as monomer components has a high compatibility between its styrene part and styrene-butadiene rubber, and a high compatibility between its cyclopentadiene and / or dicyclopentadiene part (DCPD part) and isoprene-based rubber, so it is difficult to elute from the rubber. Therefore, such a combination is considered to contribute to the maintenance of wet grip performance. (2) When the total styrene amount in the rubber composition is a certain amount or more, the intermolecular friction of the bulky styrene part increases, so the energy loss increases, which is considered to contribute to the improvement of wet grip performance. (3) By making the tire weight relatively small, the centrifugal force applied during running is suppressed, and it becomes difficult for the softener to escape from the rubber composition, which is considered to contribute to the maintenance of wet grip performance. And it is considered that the above (1) to (3) cooperate to maintain the wet grip performance even after long-term use.

[0011] The right side of the formula (1) is preferably 0.140, more preferably 0.135. By satisfying the formula (1) under more severe conditions, it is considered that the effect of the present invention of improving the wet grip performance after long-term use is more exerted.

[0012] The rubber component preferably contains butadiene rubber.

[0013] The rubber component preferably contains butadiene rubber, styrene-butadiene rubber and isoprene-based rubber.

[0014] The rubber component preferably contains silica. By containing silica, the flexibility can be improved while suppressing the heat generation of the rubber, so that minute deformation becomes easier, which is considered to contribute to the improvement of wet grip performance.

[0015] The rubber composition contains silica and carbon black, and the content (parts by mass) of the silica with respect to 100 parts by mass of the rubber component is A SIL and the content (parts by mass) of the carbon black with respect to 100 parts by mass of the rubber component is A CB When this is the case, A SIL / A CB is preferably more than 1.0. The rubber component reinforced with silica is considered to contribute to the improvement of wet grip performance.

[0016] The copolymer resin is preferably a DCPD-C9 resin.

[0017] In this specification, the upper and lower limit numerical values related to the description of numerical ranges are numerical values that can be arbitrarily combined, and in addition, the numerical values in the examples can also be combined with the upper and lower limits. Also, when specifying a numerical range by "~", unless otherwise specified, it means that the numerical values at both ends are also included. Furthermore, in this specification, a numerical range shown as including the values at both ends also simultaneously indicates a numerical range that does not include either one of the values at both ends and a numerical range that does not include both of the values at both ends, as long as it does not conflict with the gist of the present invention.

[0018] [Definitions] The "tread part" is a member including the part that forms the tread contact surface of the tire. In the tire radial cross-section, when there are members such as a reinforcing layer and a carcass layer that reinforce and form the tire skeleton on the inner side in the tire radial direction, it is a member arranged on the outer side in the tire radial direction compared to them.

[0019] The "rubber component of the rubber composition" is a component that contributes to cross-linking within the rubber composition, and generally has a weight average molecular weight (Mw) of 10,000 or more.

[0020] "Total styrene content St in the rubber composition" refers to the total styrene content (mass %) in the rubber composition when the mass of the rubber component is 100 mass %, which is the total amount of the styrene content in the styrene part contained in the rubber component and the styrene content in the compounding agents other than the rubber component. The styrene part is not particularly limited as long as it has a styrene structure. For example, styrene, α-methylstyrene, vinyltoluene, chlorostyrene, etc. can be mentioned. That is, first, for each rubber component, a value obtained by multiplying the styrene content (mass %) of each styrene part by the mass fraction in the rubber component is calculated, and the sum value (mass %) obtained by adding these values is used. Next, for the styrene-containing compounding agents other than the rubber component contained in the rubber composition, a value obtained by multiplying the styrene content (mass %) of each styrene-containing compounding agent by the mass fraction relative to 100 parts by mass of the rubber component is calculated, and the sum value (mass %) obtained by adding them is used. The value obtained by summing both sum values is defined as the total styrene content St (mass %). Therefore, it is calculated by {Σ (content of styrene part in each styrene-containing rubber (mass %) × content of each styrene-containing rubber in the rubber component (mass %) / 100) + Σ (content of styrene part in each styrene-containing compounding agent other than the rubber component (mass %) × compounding amount of each styrene-containing compounding agent relative to 100 parts by mass of the rubber component (parts by mass) / 100)}. For example, when the rubber component consists of 30 mass % of the first SBR (styrene content: 25 mass %), 60 mass % of the second SBR (styrene content: 27.5 mass %), and 10 mass % of BR, and the rubber composition further contains, in addition to the rubber component, 20 parts by mass of the first resin having a styrene part (styrene content: 5 mass %) and 10 parts by mass of the second resin having a styrene part (styrene content: 1 mass %) relative to 100 parts by mass of the rubber component, the total styrene content St in the rubber composition relative to 100 mass % of the rubber component is 25.1 mass % = {(25 × 30 / 100 + 27.5 × 60 / 100 + 0 × 10 / 100) + (5 × 20 / 100 + 1 × 10 / 100)}.

[0021] "Normal state" refers to a no-load state in which it is assembled to a normal rim and filled with air at normal internal pressure.

[0022] "Dimensions of each part of the tire" are, unless otherwise specified, values specified in the normal state for those appearing on the outer surface of the tire, while those existing inside the tire or on the tire cut surface are, for example, values specified in a state where the tire is cut by a plane including the tire rotation axis and the cut tire piece is held in the rim width of a normal rim.

[0023] "Normal rim" is the rim defined for each tire in a standard system including the standard on which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Association), it refers to the standard rim in the applicable sizes described in the "JATMA YEAR BOOK"; in the case of ETRTO (The European Tyre and Rim Technical Organisation), it refers to the "Measuring Rim" described in the "STANDARDS MANUAL"; in the case of TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" described in the "YEAR BOOK". Refer to JATMA, ETRTO, and TRA in that order, and follow the relevant standard if there is an applicable size during the reference. In the case of a tire not defined in the above standards, it refers to the narrowest-rim-width one among the rims with the smallest diameter that can be assembled with the tire and can hold the internal pressure (i.e., does not cause air leakage between the rim and the tire).

[0024] "Normal internal pressure" refers to the air pressure specified for each tire in the standard system including the standards on which the tire is based. For example, in the case of JATMA, it is the "maximum air pressure"; in the case of ETRTO, it is "INFLATION PRESSURE"; and in the case of TRA, it refers to the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". Similar to the case of normal rims, refer to JATMA, ETRTO, and TRA in this order. If there is an applicable size during the reference, follow the corresponding standard. In the case of a tire not specified in the above standards, it refers to the normal internal pressure (but not less than 250 kPa) of another tire size described with the normal rim as the standard rim (however, it should be specified in the standard). If there are multiple normal internal pressures not less than 250 kPa described, the minimum value among them shall be referred to.

[0025] "Normal load" refers to the load specified for each tire in the standard system including the standards on which the tire is based. For example, in the case of JATMA, it is the "maximum load capacity"; in the case of ETRTO, it is "LOAD CAPACITY"; and in the case of TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". Similar to the case of normal rims and normal internal pressures, refer to JATMA, ETRTO, and TRA in this order. If there is an applicable size during the reference, follow the corresponding standard. In the case of a tire not specified in the above standards, the maximum load capacity W L calculated separately shall be taken as the normal load.

[0026] "Maximum load capacity W L " is calculated by the following formula. "V" is the virtual volume of the tire (mm 3) "Dt" is the outer diameter of the tire (mm) in the normal state, "Ht" is the cross-sectional height of the tire in the cross-section of the tire by the plane including the tire rotation axis (mm), and "Wt" is the cross-sectional width of the tire in the normal state (mm). When the rim diameter of the tire is R, Ht can be obtained by (Dt - R) / 2. Wt is the value obtained by excluding patterns, characters, etc. on the tire sidewall. Note that the maximum load capacity is synonymous with the above-mentioned normal load.

[0027]

Number

[0028] "The weight of the tire" refers to the weight of the tire alone, excluding the weight of the rim. On the other hand, when the inner cavity of the tire is provided with a member made of sponge or sealant or a sensor member, etc., the weight including them is used.

[0029] "The softening agent" is a material that imparts plasticity to the rubber component, and is a concept including both a softening agent that is liquid (liquid state) at room temperature (25°C) and a softening agent that is solid at room temperature (25°C). Examples of the softening agent include resin, oil, liquid rubber, ester plasticizer, etc. "The content of the softening agent" also includes the amount of the softening agent in the rubber component stretched by the softening agent.

[0030] [Measurement method] "The content of the styrene part" is calculated by pyrolysis gas chromatography. Note that in this specification, "pyrolysis gas chromatography" refers to a method of heating a sample with a pyrolysis device, separating each component contained in the gas-phase components generated by this heating with a separation column, and analyzing each isolated component.

[0031] "The vinyl content (amount of 1,2-bonded butadiene units)" is calculated by pyrolysis gas chromatography in the same manner as the content of the above-mentioned styrene part.

[0032] "Cis content (amount of cis-1,4-bonded butadiene units)" is a value calculated by infrared absorption spectrum analysis in accordance with JIS K 6239-2:2017, and is applied to rubber components having repeating units derived from butadiene such as BR, for example.

[0033] "Glass transition temperature Tg" is a value determined by differential scanning calorimetry (DSC) in accordance with JIS K 7121, and is applied to SBR, for example. For example, when SBR contains extender oil, it is measured for a sample after removing the extender oil using acetone in accordance with JIS K 6229.

[0034] "Weight average molecular weight (Mw)" can be determined by standard polystyrene conversion based on the measured values by gel permeation chromatography (GPC) (for example, GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKgel SuperMultipore HZ-M manufactured by Tosoh Corporation). It is applied to SBR, BR, etc., for example.

[0035] "N2SA of carbon black" is measured in accordance with JIS K 6217-2:2017.

[0036] "N2SA of silica" is measured by the BET method in accordance with ASTM D3037-93.

[0037] "Average primary particle diameter" is a value obtained by photographing particles with a transmission or scanning electron microscope and calculating the arithmetic average of the particle diameters of 400 particles. When the shape of the particles is spherical, the diameter of the sphere is taken as the particle diameter, and when the shape is other than spherical, the equivalent circle diameter ({positive square root of 4×(particle area) / π}) is calculated from the microscope image and taken as the particle diameter. The average primary particle diameter is applied to silica, carbon black, etc.

[0038] "Softening point of resin" is measured with a ring and ball type softening point measuring device for the softening point defined in JIS K 6220-1:2015 7.7, and is the temperature at which the ball drops.

[0039] [Tire] Regarding the tire which is one embodiment of the present invention, it will be described below with reference to the drawings as appropriate. However, the drawings used are only those specifically showing one embodiment, and the present invention is not limited by these drawings.

[0040] The tire according to this embodiment is a tire provided with a tread portion having a rubber layer composed of a predetermined rubber composition, wherein the maximum load capacity of the tire is W L (kg), the weight of the tire is G (kg), and when the mass of the rubber component is 100% by mass, and the total styrene amount (% by mass) in the rubber composition is St, then W L and G and St satisfy the following formulas (1) and (2), and it is a tire. (1) G / W L <0.0145 (2) St / (G / W L )>8

[0041] The tread portion only needs to have a rubber layer composed of the predetermined rubber composition. For example, when the tread portion consists of only one layer, the layer corresponds to the rubber layer composed of the predetermined rubber composition, and when the tread portion consists of a plurality of layers including a cap tread and a base tread, any one of the layers may correspond to the rubber layer composed of the predetermined rubber composition. However, when the tread portion consists of a plurality of layers, it is preferable that the rubber layer constituting the tread contact surface, that is, the cap tread, is the rubber layer composed of the predetermined rubber composition.

[0042] <Formula (1)> The value on the right side of formula (1) is preferably 0.0144, more preferably 0.0142, still more preferably 0.140, still more preferably 0.139, still more preferably 0.137, still more preferably 0.135. Regarding the lower limit of the value of G / W on the left side of formula (1) L there is no particular limitation, but for example, it is 0.0100.

[0043] Regarding formula (1), the tire weight can be increased or decreased by adjusting the volume etc. of each member constituting the tire, and the maximum load capacity can be increased or decreased by adjusting the strength of each member constituting the tire. As a result, the value on the left side of formula (1) can be adjusted to be less than a predetermined value.

[0044] <Formula (2)> The value on the right side of formula (2) is preferably 10, more preferably 20, still more preferably 30, still more preferably 100, still more preferably 900, still more preferably 950, still more preferably 990, still more preferably 1100, still more preferably 1200. There is no particular limitation on the upper limit of the value of St / (G / W L ) on the left side of formula (2), but it is, for example, 3000.

[0045] Regarding formula (2), since St which is the numerator on the left side is the total amount of the content of the styrene part contained in the rubber component and the content of the styrene part contained in the compounding agents other than the rubber component, the value of St can be increased by using a rubber component or a compounding agent having a high content of the styrene part, and conversely, the value of St can be decreased by using a rubber component or a compounding agent having a low content of the styrene part. On the other hand, G / W L which is the denominator on the left side of formula (2) corresponds to the left side of the above formula (1), and thus can be adjusted as described above. As a result, the value on the left side of formula (2) can be adjusted to exceed a predetermined value.

[0046] [Rubber composition] The rubber composition constituting the rubber layer of the tread part of the tire according to the present embodiment will be described below.

[0047] The rubber composition includes a rubber component containing at least one rubber selected from the group consisting of styrene-butadiene rubber and isoprene rubber, and a copolymer resin containing styrene and cyclopentadiene as monomer components.

[0048] <Rubber component> The rubber composition according to this embodiment may contain a rubber component other than at least one rubber selected from the group consisting of styrene-butadiene rubber and isoprene-based rubber. Examples of such rubber components include diene-based rubbers and non-diene-based rubbers. Among these, diene-based rubbers are preferred, but non-diene-based rubbers can also be contained within a range that does not affect the effects of the invention.

[0049] The content of the diene-based rubber in the rubber component is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 99% by mass or more. The rubber component can also consist only of a diene-based rubber.

[0050] As the diene-based rubber, any of those commonly used in the tire industry can be suitably used. For example, butadiene rubber (BR), styrene isoprene rubber (SIR), styrene isoprene butadiene rubber (SIBR), chloroprene rubber (CR), acrylonitrile butadiene rubber (NBR), etc. can be mentioned. These diene-based rubbers can be used alone or in combination of two or more. Also, as the non-diene-based rubber, rubber components commonly used in the tire industry can be used. For example, butyl-based rubber, ethylene propylene rubber, polynorbornene rubber, silicone rubber, chlorinated polyethylene rubber, fluororubber (FKM), acrylic rubber (ACM), hydrin rubber, etc. can be mentioned. These other rubber components can be used alone or in combination of two or more. Furthermore, in addition to the above rubber components, a known thermoplastic elastomer may or may not be contained.

[0051] The rubber component according to this embodiment preferably contains styrene-butadiene rubber and isoprene rubber. Another preferred aspect of the rubber component according to this embodiment is one that contains at least one rubber selected from the group consisting of styrene-butadiene rubber and isoprene rubber and butadiene rubber. Another preferred aspect of the rubber component according to this embodiment contains styrene-butadiene rubber, isoprene rubber, and butadiene rubber, and preferably consists of styrene-butadiene rubber, isoprene rubber, and butadiene rubber.

[0052] (SBR) SBR is not particularly limited, and examples include solution-polymerized SBR (S-SBR), emulsion-polymerized SBR (E-SBR), modified SBRs of these (modified S-SBR, modified E-SBR), etc. Examples of modified SBR include SBRs with modified terminals and / or main chains, modified SBRs coupled with tin, silicon compounds, etc. (condensates, those having a branched structure, etc.). These SBRs may be used alone or in combination of two or more.

[0053] From the viewpoint of the effects of the present invention, the styrene content of SBR is preferably more than 10% by mass, more preferably more than 15% by mass, and even more preferably more than 25% by mass. On the other hand, from the viewpoints of the uniformity of crosslinking and suppression of temperature dependence, the styrene content of SBR is preferably less than 60% by mass, more preferably less than 50% by mass, and even more preferably less than 45% by mass. In this specification, the styrene content of SBR is measured by the above measurement method.

[0054] The vinyl content of SBR is preferably more than 10 mol%, more preferably more than 15 mol%, and even more preferably 20 mol% or more. Also, the vinyl content of SBR is preferably less than 70 mol%, more preferably less than 65 mol%, and even more preferably less than 60 mol%. In this specification, the vinyl content of SBR is measured by the above measurement method.

[0055] The glass transition temperature (Tg) of SBR is preferably above -80°C, more preferably above -75°C, and even more preferably above -65°C from the perspective of wet grip performance. Also, from the perspective of low fuel consumption performance, the Tg of SBR is preferably -40°C or lower, more preferably -45°C or lower, even more preferably -50°C or lower, and even more preferably -55°C or lower. In the present specification, the Tg of SBR is measured by the above-mentioned measurement method.

[0056] The weight average molecular weight (Mw) of SBR is preferably above 200,000, more preferably above 300,000, and even more preferably above 400,000. Also, from the perspective of crosslinking uniformity etc., Mw is preferably less than 2,000,000, more preferably less than 1,500,000, even more preferably less than 1,000,000. The Mw of SBR is measured by the above-mentioned measurement method.

[0057] As SBR, oil-extended SBR can be used, or non-oil-extended SBR can also be used. In the present specification, as SBR, those commercially available from JSR Corporation, Sumitomo Chemical Co., Ltd., UBE Industries, Ltd., Asahi Kasei Corporation, ZS Elastomers Co., Ltd., ARLANXEO, etc. can be used.

[0058] The content of SBR in the rubber component is preferably above 15% by mass, more preferably above 25% by mass, and even more preferably above 35% by mass. Also, the content of the SBR in the rubber component is preferably less than 80% by mass, more preferably less than 70% by mass, even more preferably less than 60% by mass, and even more preferably less than 50% by mass.

[0059] (Isoprene rubber) As the isoprene rubber, for example, isoprene rubber (IR) and natural rubber, which are common in the tire industry, can be used. Natural rubber includes, in addition to unmodified natural rubber (NR), modified natural rubbers such as epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), high-purity natural rubber, and grafted natural rubber. These isoprene rubbers can be used alone or in combination of two or more.

[0060] The NR is not particularly limited, and those commonly used in the tire industry can be used. For example, SVR-1, SIR20, RSS#3, TSR20, etc. can be mentioned.

[0061] The content of isoprene rubber in the rubber component is preferably more than 15% by mass, more preferably more than 25% by mass, and even more preferably more than 35% by mass. Also, the content in the rubber component of the SBR is preferably less than 80% by mass, more preferably less than 70% by mass, even more preferably less than 60% by mass, and even more preferably less than 50% by mass.

[0062] (BR) The BR is not particularly limited. For example, BR with a cis content of less than 50 mol% (low-cis BR), BR with a cis content of 90 mol% or more (high-cis BR), rare-earth-based butadiene rubber synthesized using a rare-earth element-based catalyst (rare-earth-based BR), BR containing syndiotactic polybutadiene crystals (SPB-containing BR), modified BR (high-cis modified BR, low-cis modified BR), etc., which are common in the tire industry, can be used. Among these, high-cis BR is preferred. These BRs can be used alone or in combination of two or more.

[0063] As the high-cis BR, for example, those commercially available from Nippon Zeon Co., Ltd., UBE Industries, Ltd., JSR Corporation, etc. can be used. By containing high-cis BR, the low-temperature properties and wear resistance can be improved. The cis content of the high-cis BR is preferably more than 95 mol%, more preferably more than 96 mol%, even more preferably more than 97 mol%, and even more preferably 98 mol% or more. The cis content of the BR is measured by the above measurement method.

[0064] As for rare earth-based BR, it is synthesized using a rare earth element-based catalyst, the vinyl content is preferably less than 1.8 mol%, more preferably less than 1.6 mol%, still more preferably 1.5 mol% or less, and the cis content is preferably more than 95 mol%, more preferably more than 96 mol%, still more preferably more than 97 mol%, and even more preferably 98 mol% or more. As the rare earth-based BR, for example, those commercially available from Lanxess Co., Ltd. etc. can be used.

[0065] The SPB-containing BR is not simply one in which 1,2-syndiotactic polybutadiene crystals are dispersed in BR, but one in which they are dispersed after chemically bonding to BR. As such SPB-containing BR, those commercially available from UBE Industries, Ltd. etc. can be used.

[0066] As the modified BR, in addition to BR modified with the same functional groups etc. as described for the above SBR, modified butadiene rubber (modified BR) modified with a functional group containing at least one element selected from the group consisting of silicon, nitrogen and oxygen in the terminal and / or main chain can also be preferably used.

[0067] As other modified BR, those obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound, and in which the terminal of the modified BR molecule is bonded by a tin-carbon bond (tin-modified BR) etc. can be mentioned. Also, the modified BR may be either one that has not been hydrogenated or one that has been hydrogenated.

[0068] From the viewpoint of wear resistance performance, the weight average molecular weight (Mw) of BR is preferably more than 200,000, more preferably more than 300,000, and still more preferably more than 400,000. Also, from the viewpoints of crosslinking uniformity etc., it is preferably less than 2,000,000, more preferably less than 1,000,000, and still more preferably less than 800,000. Note that Mw can be determined by the above method.

[0069] The content of BR in the rubber component is not particularly limited, but preferably exceeds 1% by mass, more preferably exceeds 5% by mass, and still more preferably exceeds 10% by mass. Also, the content of the BR in the rubber component preferably is less than 50% by mass, more preferably less than 30% by mass, and still more preferably less than 25% by mass.

[0070] (Rubber component synthesized from recycled and biomass-derived raw materials) The monomers that are constituent units of synthetic rubbers such as SBR and BR may be derived from petroleum or recycled from rubber products such as tires and non-rubber products such as polystyrene. The monomers obtained by recycling (recycled monomers) are not particularly limited, and examples include recycled butadiene and recycled aromatic vinyl compounds. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. The aromatic vinyl compound is not particularly limited, and examples include styrene. Among them, it is preferable to use recycled butadiene (recycled butadiene) and / or recycled styrene (recycled styrene) as raw materials.

[0071] The method for producing recycled monomers is not particularly limited, and examples include being synthesized from recycled naphtha obtained by decomposing rubber products such as tires. Also, the method for producing recycled naphtha is not particularly limited, and for example, rubber products such as tires may be decomposed under high temperature and high pressure, decomposed by microwaves, or extracted after mechanical pulverization.

[0072] Furthermore, monomers that are constituent units of polymers such as SBR and BR may be derived from biomass. The biomass-derived monomers (biomass monomers) are not particularly limited, and examples include biomass-derived butadiene and biomass-derived aromatic vinyl compounds. Examples of the butadiene include 1,2-butadiene and 1,3-butadiene. The aromatic vinyl compound is not particularly limited, and examples include styrene. Also, the method for producing biomass monomers is not particularly limited, and examples include those by biological and / or chemical and / or physical conversion of animals and plants. Fermentation by microorganisms is typical as the biological conversion, and examples of the chemical and / or physical conversion include those by a catalyst, by high heat, by high pressure, by electromagnetic waves, by a critical liquid, and combinations thereof. Examples of the biomass sources of these monomers include sugars, wood, plant residues after obtaining useful components, plant-derived ethanol, biomass naphtha, and the like.

[0073] The polymers synthesized from biomass monomer components (biomass polymers) are not particularly limited, and examples include polybutadiene rubber synthesized from biomass-derived butadiene, and aromatic vinyl / butadiene copolymers synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl. Examples of the aromatic vinyl / butadiene copolymer include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0074] Whether the raw material of the polymer is derived from biomass can be determined by pMC (percent Modern Carbon) measured in accordance with ASTM D6866-10. pMC is the ratio of the 14 C concentration of the sample to the 14 C concentration of the standard modern carbon (modern standard reference), and this value is used as an index indicating the biomass ratio of the compound (rubber). The significance of this value is described below.

[0075] One mole of carbon atoms (6.02×10 23 atoms) contains approximately 6.02×10 11 atoms of 14 C, which is about one trillionth of ordinary carbon atoms. 14 The half-life of 14 C is 5730 years, and 14 C decreases regularly. Therefore, in fossil fuels such as coal, oil, and natural gas, which are thought to have been formed more than 226,000 years after carbon dioxide in the atmosphere was taken up and fixed by plants, etc., all of the 14 C element has decayed at the time of fixation. Thus, in the 21st century, fossil fuels such as coal, oil, and natural gas contain 14 no

[0076] On the other hand, 14 C is constantly produced by cosmic rays undergoing nuclear reactions in the atmosphere. Therefore, 14 C is in equilibrium between the decrease due to radioactive decay and the production due to nuclear reactions, and in the earth's atmospheric environment, 14 the amount of 14 C is constant. Therefore, the -12 C concentration of substances derived from biomass resources that are cycling in the current environment is about 1×10

[0077] This 14 C is generally measured as follows. Using accelerator mass spectrometry based on a tandem accelerator, 13 the 13 C concentration ( 12 C / 14 the 14 C concentration ( 12 C / 14As a modern standard reference for the concentration standard of C, the concentration of 14 C in the circulating carbon in nature in 1950 is adopted. As a specific reference material, the oxalic acid standard provided by NIST (National Institute of Standards and Technology) is used. The specific activity of carbon in this oxalic acid (the activity intensity of 14 C per gram of carbon) is separated for each carbon isotope, and 13 For 14 C, it is corrected to a constant value, and the value obtained by applying the decay correction from 1950 AD to the measurement date is used as the standard 14 C concentration value (100%). The ratio of this value to the value of the actually measured sample is the pMC value.

[0078] Therefore, if the rubber is made of materials derived from 100% biomass (natural system), although there are regional differences, etc., it will show a value of approximately 110 pMC (currently, in the normal state, it often does not reach 100). On the other hand, for chemical substances derived from fossil fuels such as petroleum, when the 14 C concentration is measured, it will show a value of about 0 pMC (for example, 0.3 pMC). This value corresponds to a biomass ratio of 0% mentioned above.

[0079] From the above, using materials such as rubber with a high pMC value, that is, materials such as rubber with a high biomass ratio, in the rubber composition is suitable from the perspective of environmental protection.

[0080] In addition, when the rubber component consists of only three types: IR-based rubber, SBR, and BR, if the content of any two types of rubber components is determined based on the above description, the content of the remaining one type will be naturally determined so that the total rubber component is 100% by mass.

[0081] <Filler> The rubber composition according to this embodiment preferably contains a filler. Examples of such fillers include silica, carbon black, etc. The filler may also include other fillers other than silica and carbon black. The other fillers are not particularly limited, but examples include those commonly used in the tire industry, such as aluminum hydroxide, calcium carbonate, alumina, clay, talc, etc. The other fillers may be used alone or in combination of two or more.

[0082] The filler preferably contains at least one of silica and carbon black, more preferably contains silica, and even more preferably contains silica and carbon black. Also, the filler may consist only of carbon black and silica.

[0083] (Silica) The silica is not particularly limited. For example, silica prepared by the dry method (anhydrous silica), silica prepared by the wet method (hydrous silica), etc., which are common in the tire industry, can be used. The raw material of the silica is not particularly limited. For example, it may be a raw material derived from a mineral such as quartz, or a raw material derived from a living organism such as rice husk (for example, silica using a biomass material such as rice husk as a raw material), or silica recycled from a product containing silica may also be used. Among them, hydrous silica prepared by the wet method is preferred because it has many silanol groups. These silicas may be used alone or in combination of two or more.

[0084] Silica using a biomass material as a raw material can be obtained, for example, by extracting silicate from rice husk ash obtained by burning rice husk using a sodium hydroxide solution, and reacting the silicate with sulfuric acid in the same manner as conventional wet silica to obtain a precipitate of silicon dioxide, followed by filtration, washing with water, drying, and pulverization.

[0085] Silica recycled from products containing silica can be, for example, silica recovered from products containing silica such as electronic components such as semiconductors, tires, desiccants, and filter materials such as diatomaceous earth. The method of recovery is not particularly limited and includes pyrolysis, decomposition by electromagnetic waves, etc. Among these, silica recovered from electronic components such as semiconductors or tires is preferred.

[0086] When silica crystallizes, it does not dissolve in water and the silicic acid that is its component cannot be utilized. By controlling the combustion temperature and combustion time, crystallization of silica in rice husk ash can be suppressed (see, for example, Japanese Patent Laid-Open No. 2009-2594, Akita Prefectural University Web Journal B / 2019, vol. 6, p. 216-222, etc.). Amorphous silica extracted from rice husks can be those commercially available from companies such as Wilmar.

[0087] The nitrogen adsorption specific surface area (N2SA) of silica is preferably more than 100 m 2 / g from the viewpoint of ensuring reinforcing properties and grip performance, more preferably more than 120 m 2 / g, still more preferably more than 140 m 2 / g, even more preferably more than 160 m 2 / g, even more preferably more than 170 m 2 / g, particularly preferably. Further, from the viewpoints of exothermic properties and processability, it is preferably less than 350 m 2 / g, more preferably less than 300 m 2 / g, still more preferably less than 250 m 2 / g. The N2SA of silica is measured by the above measurement method.

[0088] The average primary particle diameter of silica is preferably more than 10 nm, more preferably more than 12 nm, still more preferably more than 14 nm, and particularly preferably more than 16 nm. Also, the average primary particle diameter is preferably less than 24 nm, more preferably less than 22 nm, and still more preferably less than 20 nm. The average primary particle diameter of silica is measured by the above measurement method.

[0089] From the perspective of the effects of the present invention, the content of silica relative to 100 parts by mass of the rubber component is preferably more than 30 parts by mass, more preferably more than 40 parts by mass, and even more preferably more than 50 parts by mass. Also, from the perspective of processability, the content of silica relative to 100 parts by mass of the rubber component is preferably less than 200 parts by mass, more preferably less than 150 parts by mass, and even more preferably less than 100 parts by mass.

[0090] (Silane coupling agent) Silica is preferably used in combination with a silane coupling agent. The silane coupling agent is not particularly limited. For example, sulfide-based silane coupling agents such as bis(3-triethoxysilylpropyl)disulfide and bis(3-triethoxysilylpropyl)tetrasulfide; mercapto-based silane coupling agents such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, and 2-mercaptoethyltriethoxysilane; vinyl-based silane coupling agents such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based silane coupling agents such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and 3-(2-aminoethyl)aminopropyltriethoxysilane; glycidoxy-based silane coupling agents such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane, etc. Among them, it is preferable to contain a sulfide-based silane coupling agent and / or a mercapto-based silane coupling agent. As the silane coupling agent, for example, those commercially available from Evonik Degussa, Momentive, etc. can be used. The silane coupling agent may be used alone or in combination of two or more.

[0091] From the perspective of enhancing the dispersibility of silica, the content of the silane coupling agent is preferably more than 3 parts by mass, more preferably more than 5 parts by mass, and even more preferably more than 8 parts by mass with respect to 100 parts by mass of silica. From the perspectives of cost and processability, it is preferably less than 20 parts by mass, more preferably less than 15 parts by mass, and even more preferably less than 12 parts by mass.

[0092] (Carbon black) The carbon black is not particularly limited, and examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. The raw material of the carbon black may be a biomass material such as lignin or vegetable oil, or a pyrolysis oil obtained by pyrolyzing waste tires. Also, the manufacturing method of the carbon black may be by combustion such as the furnace method, by hydrothermal carbonization (HTC), or by thermal decomposition of methane such as the thermal black method. As commercially available products, products of Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., Columbian Carbon Company, etc. can be used. The carbon black may be used alone or in combination of two or more.

[0093] In addition to the above, from the perspective of life cycle assessment and the like, carbon black made from biomass materials such as lignin or recycled carbon black obtained by pyrolyzing and purifying products containing carbon black such as tires may also be used as the carbon black.

[0094] As used herein, "recycled carbon black" refers to carbon black obtained by pulverizing products such as used tires containing carbon black and firing the pulverized product, and in the thermogravimetric measurement method conforming to JIS K 6226-2:2003, when oxidized and burned by heating in air, it refers to carbon black in which the ratio of the mass of the ash content (ash amount), which is the non-combustible component, is 13% by mass or more. That is, the ratio of the mass (carbon amount) of the weight loss due to the oxidative combustion of the recycled carbon black is 87% by mass or less. Recycled carbon black may also be represented by rCB.

[0095] Recycled carbon black can be obtained from the thermal decomposition process of used pneumatic tires. For example, European Patent Application Publication No. 3427975 refers to "Rubber Chemistry and Technology", Vol. 85, No. 3, pages 408 to 449 (2012), particularly pages 438, 440, and 442, and describes that it can be obtained by thermal decomposition of organic materials at 550 to 800 °C with oxygen excluded or by vacuum thermal decomposition at a relatively low temperature (

[0027] ). Carbon black obtained from such a thermal decomposition process usually lacks functional groups on its surface, as mentioned in

[0004] of Patent No. 6856781 (Comparison of the surface morphology and chemistry of thermally decomposed carbon black and commercially available carbon black, Powder Technology 160 (2005) 190 to 193).

[0096] Recycled carbon black may have no functional groups on its surface or may be treated to contain functional groups on its surface. The treatment to make the surface of recycled carbon black contain functional groups can be carried out by conventional methods. For example, in European Patent Application Publication No. 3173251, carbon black obtained from a pyrolysis process is treated with potassium permanganate under acidic conditions to obtain carbon black containing hydroxyl and / or carboxyl groups on its surface. Also, in Japanese Patent No. 6856781, carbon black obtained from a pyrolysis process is treated with an amino acid compound containing at least one thiol group or disulfide group to obtain carbon black with an activated surface. The recycled carbon black according to this embodiment also includes carbon black treated to contain functional groups on its surface.

[0097] Recycled carbon black commercially available from Strable Green Carbon, LD Carbon, etc. can be used.

[0098] The average primary particle size of the carbon black is preferably 15 nm or more, more preferably 18 nm or more, and even more preferably 20 nm or more. On the other hand, from the viewpoint of obtaining reinforcing properties, the average primary particle size is preferably 100 nm or less, more preferably 80 nm or less, and even more preferably 50 nm or less. The average primary particle size of the carbon black is measured by the above measurement method.

[0099] The nitrogen adsorption specific surface area (N2SA) of the carbon black is preferably less than 200 m 2 / g, more preferably less than 180 m 2 / g, and even more preferably less than 150 m 2 / g, from the viewpoint of the effects of the present invention. Also, the N2SA is preferably more than 30 m 2 / g, more preferably more than 50 m 2 / g, and even more preferably more than 70 m 2 / g. The N2SA of the carbon black is measured by the above measurement method.

[0100] From the viewpoint of reinforcing property, the content of carbon black with respect to 100 parts by mass of the rubber component is preferably more than 3 parts by mass, more preferably more than 5 parts by mass, and still more preferably more than 9 parts by mass. From the viewpoint of the effect of the present invention, it is preferably less than 50 parts by mass, more preferably less than 30 parts by mass, and still more preferably less than 20 parts by mass.

[0101] (A SIL / A CB ) The content (parts by mass) of the silica with respect to 100 parts by mass of the rubber component is A SIL and the content (parts by mass) of the carbon black with respect to 100 parts by mass of the rubber component is A CB In this case, A SIL / A CB is preferably more than 1.0. A SIL / A CB is more preferably more than 2.0, still more preferably more than 3.0, still more preferably more than 4.0, still more preferably more than 5.0, still more preferably more than 6.0. On the other hand, there is no particular limitation on the upper limit of A SIL / A CB and carbon black may not be included.

[0102] <Copolymer resin> The rubber composition according to the present embodiment contains a copolymer resin (hereinafter simply referred to as "copolymer resin") containing styrene and cyclopentadiene as monomer components.

[0103] The copolymer resin is not particularly limited as long as it contains cyclopentadiene and styrene as monomer components, and may further contain other monomer components. Further, those obtained by hydrogenating them or modified ones may also be used.

[0104] As the "styrene" constituting the monomer component, a compound having a styrene structure other than styrene may be used. Examples thereof include styrene, α-methylstyrene, vinyltoluene, chlorostyrene, and the like. Styrene-based monomers such as vinyltoluene (methylstyrene) are contained in, for example, the C9 fraction. The other monomer components are not particularly limited, but monomer components commonly used in petroleum resins are preferred. Examples thereof include C9 fractions other than monomers having a styrene structure. Examples of the C9 fraction other than monomers having a styrene structure include at least one selected from the group consisting of coumarone, indene, methylindene, and the like.

[0105] The copolymer resin is preferably a DCPD-C9 resin which is a copolymer of cyclopentadiene and / or dicyclopentadiene and a C9 fraction. Further, it may be a hydrogenated product or a modified product of the DCPD-C9 resin.

[0106] As the copolymer resin containing styrene and cyclopentadiene as monomer components, for example, those commercially available from ExxonMobil, ENEOS Corporation, Nippon Zeon Co., Ltd., Maruzen Petrochemical Co., Ltd., and the like can be used. The copolymer resin may be used alone or in combination of two or more.

[0107] From the viewpoint of the effects of the present invention, the content of the styrene part in the copolymer resin is preferably 0.5% by mass or more, more preferably 0.8% by mass or more, and still more preferably 1.0% by mass or more. The upper limit of the content of the styrene part is not particularly limited, but may be, for example, less than 50% by mass, less than 25% by mass, less than 10% by mass, 5% by mass or less, 3% by mass or less, or 2% by mass or less.

[0108] The softening point of the copolymer resin is preferably above 70°C, more preferably above 80°C, still more preferably above 90°C, and particularly preferably above 100°C from the viewpoint of the effects of the present invention. Also, from the viewpoints of processability and improvement in the dispersibility of the rubber component and the filler, it is preferably less than 150°C, more preferably less than 140°C, and still more preferably less than 130°C. The softening point of the resin is measured by the above measurement method.

[0109] The content of the copolymer resin with respect to 100 parts by mass of the rubber component (total content when two or more are contained) is preferably more than 3 parts by mass, more preferably more than 5 parts by mass, and still more preferably 10 parts by mass or more. On the other hand, from the viewpoint of suppressing exothermic properties, the content is preferably less than 80 parts by mass, more preferably less than 60 parts by mass, and still more preferably less than 40 parts by mass.

[0110] <Total styrene amount St> The total styrene amount St (mass%) is not particularly limited in the present embodiment as long as it satisfies the above formulas (1) and (2), but usually, St is preferably 0.2 mass% or more, more preferably 2.0 mass% or more, still more preferably 4.0 mass% or more, and still more preferably 5.0 mass% or more. On the other hand, it is preferably 25.0 mass% or less, more preferably 20.0 mass% or less, and still more preferably 15.0 mass% or less.

[0111] <Other compounding agents> The rubber composition according to the present embodiment may appropriately contain compounding agents generally used in the conventional tire industry, such as softeners, processing aids, vulcanized rubber particles, waxes, stearic acid, zinc oxide, anti-aging agents, vulcanizing agents, vulcanization accelerators, etc., in addition to the above components.

[0112] (Softener) The plasticizer is as described above. Specifically, examples include resins, oils, liquid polymers, ester plasticizers, etc. These plasticizers may be derived from petroleum, may be derived from biomass, or may be derived from naphtha recycled from rubber products or non-rubber products. Further, low-molecular-weight hydrocarbon components obtained by pyrolyzing and extracting used tires or products containing various components may be used as the plasticizer. The plasticizer may be used alone or in combination of two or more.

[0113] ≪Resin≫ The rubber composition according to this embodiment may contain other resins other than the copolymer resin. The other resins are not particularly limited, but resins commonly used in the tire industry can be used. For example, aromatic vinyl resins, dicyclopentadiene resins, C9 resins, C5 resins, C5C9 resins, terpene resins, rosin resins, phenolic resins, etc. may be mentioned. The other resins may be used alone or in combination of two or more.

[0114] Aromatic vinyl resin In this specification, the "aromatic vinyl resin" refers to a resin containing at least one aromatic vinyl compound selected from the group consisting of styrene, α-methylstyrene, vinyltoluene, p-chlorostyrene, etc. as a monomer component. As the aromatic vinyl resin, a homopolymer of α-methylstyrene or styrene or a copolymer of α-methylstyrene and styrene is preferable, and a copolymer of α-methylstyrene and styrene is more preferable because of its economy, ease of processing, and excellent heat generation properties. As the aromatic vinyl resin, for example, those commercially available from companies such as Kreton, Eastman Chemical, and Mitsui Chemicals, Inc. can be used. The resin may be used alone or in combination of two or more.

[0115] Dicyclopentadiene resin In this specification, the "dicyclopentadiene-based resin" refers to a resin containing dicyclopentadiene as a monomer component. As the dicyclopentadiene-based resin, for example, those commercially available from ExxonMobil, ENEOS Corporation, Nippon Zeon Co., Ltd., Maruzen Petrochemical Co., Ltd., etc. can be used. The resin may be used alone or in combination of two or more.

[0116] C9 resin In this specification, the "C9 resin" refers to a resin obtained by polymerizing a C9 fraction, which may be a polymer of the C9 fraction alone or a copolymer obtained by copolymerizing the C9 fraction with other components. Examples of the C9 fraction include at least one petroleum fraction having 8 to 10 carbon atoms equivalent selected from the group consisting of alkylstyrenes such as vinyltoluene, coumarone, indene, methylindene, etc. Specific examples of the C9 resin include, for example, coumarone-indene resin, coumarone resin, indene resin, etc. The resin may be used alone or in combination of two or more.

[0117] C5 resin In this specification, the "C5 resin" refers to a resin obtained by polymerizing a C5 fraction other than cyclopentadiene, which may be hydrogenated or modified. Examples of the C5 fraction other than cyclopentadiene include at least one petroleum fraction having 4 to 5 carbon atoms equivalent selected from the group consisting of isoprene, pentane, isopentane, neopentane, pentene, pentadiene, etc. The resin may be used alone or in combination of two or more.

[0118] C5C9 resin The "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, which may be hydrogenated or modified. As the C5C9 petroleum resin, for example, those commercially available from Tosoh Corporation, LUHUA Co., Ltd., etc. can be used. The resin may be used alone or in combination of two or more.

[0119] Terpene resin The terpene resin refers to a resin containing at least one terpene compound selected from the group consisting of α-pinene, β-pinene, limonene, dipentene, etc. as the monomer component with the highest content, preferably containing 50 mol% or more. It may be hydrogenated or modified. Specific examples of terpene resins include, for example, polyterpene resins containing only one or more of the above terpene compounds as monomer components; aromatic-modified terpene resins containing the terpene compounds and aromatic compounds as monomer components; terpene-phenol resins containing the terpene compounds and phenolic compounds as monomer components, etc. Examples of the aromatic compounds serving as monomer components of aromatic-modified terpene resins include at least one selected from the group consisting of styrene, α-methylstyrene, vinyltoluene, divinyltoluene, etc. Examples of the phenolic compounds serving as monomer components of terpene-phenol resins include at least one selected from the group consisting of phenol, bisphenol A, cresol, xylenol, etc. The resin may be used alone or in combination of two or more.

[0120] Rosin resin The rosin resin refers to a resin containing at least one rosin acid compound selected from the group consisting of abietic acid, neoabietic acid, palustric acid, isopimaric acid, etc. It may be hydrogenated or modified. The rosin resin is not particularly limited, and examples include natural resin rosin, rosin-modified resins modified by hydrogenation, disproportionation, dimerization, esterification, etc. The resin may be used alone or in combination of two or more.

[0121] Phenolic resin The phenolic resin refers to a resin containing a phenolic compound such as phenol or cresol as the monomer component with the highest content, preferably containing 50 mol% or more. The phenolic resin is not particularly limited, and examples thereof include phenol formaldehyde resin, alkylphenol formaldehyde resin, alkylphenol acetylene resin, oil-modified phenol formaldehyde resin, and the like. The resin may be used alone or in combination of two or more.

[0122] <<Softening point>> From the viewpoint of wet grip performance, the softening point of other resins is preferably above 80 °C, more preferably above 90 °C, and even more preferably above 100 °C. From the viewpoints of processability and improvement of the dispersibility of the rubber component and the filler, it is preferably less than 150 °C, more preferably less than 140 °C, and even more preferably less than 130 °C. The softening point of other resins is measured by the above measurement method.

[0123] <<Content>> The content of other resins with respect to 100 parts by mass of the rubber component (total content when containing two or more kinds) is preferably more than 10 parts by mass, more preferably more than 15 parts by mass, and even more preferably 20 parts by mass or more. On the other hand, from the viewpoint of suppressing exothermicity, the content is preferably less than 80 parts by mass, more preferably less than 60 parts by mass, even more preferably less than 40 parts by mass, even more preferably less than 20 parts by mass, or may not be contained.

[0124] <<Oil>> Examples of the oil include mineral oil, vegetable oil, animal oil, etc. Examples of the mineral oil include paraffinic mineral oil (mineral oil), naphthenic mineral oil, aromatic mineral oil, etc. Specific examples of the mineral oil include, for example, MES (Mild Extract Solvated), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), RAE (Residual Aromatic Extract), etc. Also, a mineral oil with a low content of polycyclic aromatic (polycyclic aromatic compound: PCA) compounds can be used for environmental measures. Examples of the low PCA content mineral oil include MES, TDAE, heavy naphthenic oil, etc. Also, from the perspective of life cycle assessment, it is also possible to use waste oil after being used in a rubber mixer or an engine, or purified waste cooking oil used in a restaurant. The oil may be used alone or in combination of two or more.

[0125] Vegetable oil includes, for example, linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar oil, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grape seed oil, wood rosin, etc. Furthermore, vegetable oils include refined oils (such as salad oil) obtained by refining the above oils, transesterified oils obtained by transesterifying the above oils, hydrogenated oils obtained by hydrogenating the above oils, thermally polymerized oils obtained by thermally polymerizing the above oils, oxidation polymerized oils obtained by oxidizing the above oils, and waste cooking oils recovered from those used as edible oils, etc. Note that the vegetable oil may be liquid or solid at room temperature (25°C).

[0126] The vegetable oil preferably contains acylglycerol, and more preferably contains triacylglycerol. In the present specification, acylglycerol refers to a compound in which a hydroxy group of glycerin and a fatty acid are ester-bonded. The acylglycerol is not particularly limited, and may be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Further, the acylglycerol may be a monomer, a dimer, or a multimer of trimer or higher. Note that acylglycerols of dimer or higher can be obtained by thermal polymerization, oxidative polymerization, or the like. Also, the acylglycerol may be liquid or solid at room temperature (25°C).

[0127] The method for confirming whether the acylglycerol is contained in the rubber composition is not particularly limited, but 1 it can be confirmed by 1H-NMR measurement. For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at room temperature (25°C) for 24 hours. After removing the rubber composition, 1 1H-NMR is measured. When the signal of tetramethylsilane (TMS) is set to 0.00 ppm, signals around 5.26 ppm, around 4.28 ppm, and around 4.15 ppm are observed, and these signals are presumed to be signals derived from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group. In this paragraph, "around" means a range of ±0.10 ppm.

[0128] The fatty acid is not particularly limited and may be an unsaturated fatty acid or a saturated fatty acid. Examples of the unsaturated fatty acid include monounsaturated fatty acids such as oleic acid, and polyunsaturated fatty acids such as linoleic acid and linolenic acid. Examples of the saturated fatty acid include butyric acid and lauric acid.

[0129] Among them, as the fatty acid, it is desirable to contain a fatty acid with few double bonds, that is, a saturated fatty acid or a monounsaturated fatty acid, and oleic acid is preferred. As the vegetable oil containing such a fatty acid, for example, a vegetable oil containing a saturated fatty acid or a monounsaturated fatty acid may be used, or a vegetable oil subjected to modification such as transesterification may be used. Further, in order to produce a vegetable oil containing such a fatty acid, plants may be improved by variety improvement, genetic recombination, genome editing, etc.

[0130] As the vegetable oil, for example, those commercially available from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Co., Ltd., Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Fuji Kogyo Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0131] Examples of the animal oil include fish oil, beef tallow, whale oil, or oleyl alcohol derived therefrom.

[0132] From the viewpoint of processability, the content of the oil with respect to 100 parts by mass of the rubber component when containing the oil is preferably 8 parts by mass or more, more preferably 10 parts by mass or more, and further preferably 20 parts by mass or more. From the viewpoint of wear resistance performance, 80 parts by mass or less is preferable, 60 parts by mass or less is more preferable, and 40 parts by mass or less is further preferable. The oil content includes the amount of oil contained in the oil-extended rubber.

[0133] ≪Liquid Rubber≫ The liquid rubber is not particularly limited as long as it is a polymer in a liquid state at room temperature (25 °C). Examples thereof include liquid butadiene rubber (liquid BR), liquid styrene-butadiene rubber (liquid SBR), liquid isoprene rubber (liquid IR), liquid styrene-isoprene rubber (liquid SIR), liquid farnesene rubber, etc. The liquid rubber may be used alone or in combination of two or more.

[0134] When containing liquid rubber, the content relative to 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and still more preferably 5 parts by mass or more. Further, the content of the liquid rubber is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and still more preferably 10 parts by mass or less. The content of the liquid rubber includes the amount of the extended liquid rubber used for extending the rubber component.

[0135] ≪Ester plasticizer≫ Examples of the ester plasticizer include dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), bis(2-ethylhexyl) azelate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), diundecyl phthalate (DUP), dibutyl phthalate (DBP), dioctyl sebacate (DOS), tributyl phosphate (TBP), trioctyl phosphate (TOP), triethyl phosphate (TEP), trimethyl phosphate (TMP), thymidine triphosphate (TTP), tricresyl phosphate (TCP), trixylenyl phosphate (TXP), etc. The ester plasticizer may be used alone or in combination of two or more.

[0136] When containing the ester plasticizer, the content relative to 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and still more preferably 5 parts by mass or more. Further, the content of the liquid rubber is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and still more preferably 10 parts by mass or less. The content of the ester plasticizer includes the amount of the extended ester plasticizer used for extending the rubber component.

[0137] (Vulcanized rubber particles) The vulcanized rubber particles are particles made of vulcanized rubber. Specifically, rubber powder etc. specified in JIS K 6316:2017 can be used. From the viewpoints of environmental consideration and cost, recycled rubber powder produced from crushed waste tires etc. is preferred. The vulcanized rubber particles may be used alone or in combination of two or more.

[0138] The vulcanized rubber particles are not particularly limited, and may be non-modified vulcanized rubber particles or modified vulcanized rubber particles. As commercially available products of vulcanized rubber, for example, products of Lehigh, Murakami Rubber Industry Co., Ltd., etc. can be used.

[0139] When containing vulcanized rubber particles, the content relative to 100 parts by mass of the rubber component can be appropriately adjusted, for example, in the range of more than 1 part by mass and less than 80 parts by mass.

[0140] (Stearic acid) When containing stearic acid, the content relative to 100 parts by mass of the rubber component is preferably 0.5 part by mass or more, more preferably 1 part by mass or more, from the viewpoint of processability. Also, from the viewpoint of vulcanization rate, it is preferably 10 parts by mass or less, more preferably 5 parts by mass or less.

[0141] (Zinc oxide) When containing zinc oxide, the content relative to 100 parts by mass of the rubber component is preferably 0.5 part by mass or more, more preferably 1.0 part by mass or more, further preferably 1.5 part by mass or more, from the viewpoint of processability. Also, from the viewpoint of abrasion resistance performance, it is preferably 5.0 parts by mass or less, more preferably 4.5 parts by mass or less, further preferably 4.0 parts by mass or less.

[0142] (Wax) The wax is not particularly limited, and any wax commonly used in the tire industry can be preferably used. For example, petroleum waxes, mineral waxes, synthetic waxes, plant-derived waxes, etc. can be mentioned. Among them, petroleum waxes and plant-derived waxes are preferred, and petroleum waxes are more preferred. Examples of plant-derived waxes include rice wax, carnauba wax, candelilla wax, etc. Examples of petroleum waxes include paraffin wax, microcrystalline wax, these selected special waxes, etc., and paraffin wax is preferred. Note that the wax according to this embodiment does not contain stearic acid. As the wax, for example, those commercially available from Ouchi Shinsei Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Paramelt Co., etc. can be used. The wax may be used alone or in combination of two or more kinds.

[0143] When containing wax, the content based on 100 parts by mass of the rubber component is preferably 0.5 part by mass or more, more preferably 1 part by mass or more, from the viewpoint of the weather resistance of the rubber. Also, from the viewpoint of preventing the whitening of the tire due to blooming, it is preferably 10 parts by mass or less, more preferably 5 parts by mass or less.

[0144] (Antioxidant) The anti-aging agent is not particularly limited, but examples include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; p-phenylenediamine-based anti-aging agents such as N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), N,N'-ditoly-p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline-based anti-aging agents such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based anti-aging agents such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; bis, tris, and polyphenol-based anti-aging agents such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Among them, p-phenylenediamine-based anti-aging agents and quinoline-based anti-aging agents are preferred, and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and polymers of 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. As commercial products, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinsei Chemical Industry Co., Ltd., Flexsys Co., etc. can be used. The anti-aging agent may be used alone or in combination of two or more kinds.

[0145] When containing an anti-aging agent, from the viewpoint of the ozone crack resistance of the rubber, the content based on 100 parts by mass of the rubber component is preferably 0.5 part by mass or more, and more preferably 1 part by mass or more. Also, from the viewpoints of abrasion resistance performance and wet grip performance, it is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less.

[0146] (Processing aid) Examples of processing aids include fatty acid metal salts, fatty acid amides, amide esters, silica surfactants, fatty acid esters, mixtures of fatty acid metal salts and amide esters, mixtures of fatty acid metal salts and fatty acid amides, etc. As the processing aid, those commercially available from, for example, Schill + Seilacher, Performance Additives, etc. can be used. The processing aid may be used alone or in combination of two or more.

[0147] When containing a processing aid, the content thereof with respect to 100 parts by mass of the rubber component is preferably 0.5 part by mass or more, more preferably 1 part by mass or more, from the viewpoint of exerting the effect of improving processability. Also, from the viewpoints of abrasion resistance performance and fracture strength, it is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, still more preferably 5 parts by mass or less.

[0148] (Vulcanizing agent) Sulfur is preferably used as the vulcanizing agent. As sulfur, powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, etc. can be used. The vulcanizing agent may be used alone or in combination of two or more.

[0149] When containing sulfur as the vulcanizing agent, the content thereof with respect to 100 parts by mass of the rubber component is preferably 0.1 part by mass or more, more preferably 0.3 part by mass or more, still more preferably 0.5 part by mass or more, from the viewpoint of ensuring a sufficient vulcanization reaction. Also, from the viewpoint of deterioration prevention, it is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, still more preferably 3.0 parts by mass or less. In addition, when using oil-containing sulfur as the vulcanizing agent, the content of the vulcanizing agent is the total content of the pure sulfur content contained in the oil-containing sulfur.

[0150] Examples of vulcanizing agents other than sulfur include alkylphenol sulfur chloride condensates, sodium 1,6-hexamethylene-dithiothiosulfate dihydrate, 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane, etc. As these vulcanizing agents other than sulfur, those commercially available from companies such as Tago Chemical Industry Co., Ltd., Rancess Co., Ltd., and Flexsys can be used.

[0151] (Vulcanization accelerator) Examples of vulcanization accelerators include, for example, sulfenamide-based, thiazole-based, thiuram-based, thiourea-based, guanidine-based, dithiocarbamic acid-based, aldehyde-amine-based or aldehyde-ammonia-based, imidazoline-based, or xanthate-based vulcanization accelerators, etc. Among them, sulfenamide-based, thiazole-based, and guanidine-based vulcanization accelerators are preferred. The vulcanization accelerator may be used alone or in combination of two or more.

[0152] Examples of sulfenamide-based vulcanization accelerators include, for example, N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N,N-dicyclohexyl-2-benzothiazolylsulfenamide (DCBS), etc. Among them, N-cyclohexyl-2-benzothiazolylsulfenamide (CBS) is preferred.

[0153] Examples of thiazole-based vulcanization accelerators include, for example, 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, di-2-benzothiazolyldisulfide, etc. Among them, 2-mercaptobenzothiazole is preferred.

[0154] Examples of guanidine-based vulcanization accelerators include 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salt of dicatecholborate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, 1,3-di-o-cumenyl-2-propionylguanidine, and the like. Among them, 1,3-diphenylguanidine (DPG) is preferred.

[0155] When containing a vulcanization accelerator, the content based on 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 1.5 parts by mass or more. Also, the content of the vulcanization accelerator based on 100 parts by mass of the rubber component is preferably 8 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 6 parts by mass or less. By setting the content of the vulcanization accelerator within the above range, the breaking strength and elongation tend to be ensured.

[0156] <Various materials containing carbon atoms> In this specification, various materials containing carbon atoms (such as rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from carbon dioxide in the atmosphere. As a method for obtaining the various materials from carbon dioxide, carbon dioxide may be directly converted, or methane obtained through a methanation process of synthesizing methane from carbon dioxide may be converted.

[0157] [Manufacturing method] The rubber composition can be manufactured by a known method. For example, it can be manufactured by kneading the above-mentioned respective components using a rubber kneading device such as an open roll, a closed kneader (Banbury mixer, kneader, etc.).

[0158] The kneading process includes, for example, a base kneading process of kneading compounding agents and additives other than the vulcanizing agent and the vulcanization accelerator, and a final kneading (F kneading) process of adding the vulcanizing agent and the vulcanization accelerator to the kneaded product obtained in the base kneading process and kneading them. Further, the base kneading process can be divided into a plurality of processes if desired.

[0159] Although the kneading conditions are not particularly limited, for example, in the base kneading step, kneading is performed at a discharge temperature of 150 to 170°C for 3 to 10 minutes, and in the final kneading step, kneading is performed at 70 to 110°C for 1 to 5 minutes.

[0160] The tire according to this embodiment can be manufactured by a normal method using the rubber composition. That is, the rubber composition in the unvulcanized state is extruded by an extruder equipped with a die of a predetermined shape to match the shape of the rubber layer of the tread portion, and on a tire molding machine, it is bonded together with other tire members while adjusting to a predetermined tire structure, and an unvulcanized tire is formed by molding by a normal method. By heating and pressurizing this unvulcanized tire in a vulcanizer, a tire can be manufactured. The vulcanization conditions are not particularly limited, and for example, a method of vulcanizing at 140 to 170°C for 10 to 40 minutes can be mentioned.

[0161] [Use] In this specification, the tire can be used for any application, regardless of whether it is a pneumatic tire or a non-pneumatic tire, and can be used as a passenger car tire, a large passenger car tire, a large SUV tire, a racing tire, a motorcycle tire, a heavy-duty tire, or a run-flat tire. Note that a passenger car tire is a tire assumed to be mounted on an automobile running on four wheels, and refers to a tire with a maximum load capacity of less than 1400 kg. Also, a heavy-duty tire refers to a tire with a maximum load capacity of 1400 kg or more. Also, in this specification, the tire can be used for winter tires such as studless tires in addition to all-season tires and summer tires.

Example

[0162] Hereinafter, examples (Examples) considered to be preferable in practice are shown, but the scope of the present invention is not limited to the examples. According to each table, a rubber layer of the tread portion obtained using various chemicals shown below, and a tire having a tire structure are examined, and the results calculated based on the following evaluation method are shown at the bottom of each table.

[0163] [Various chemicals] The various chemicals used in the following Examples and Comparative Examples are summarized below. NR: SVR-L SBR: Toughdene 3830 (S-SBR manufactured by Asahi Kasei Corporation, styrene content: 33% by mass, containing 37.5% by mass of oil based on 100% by mass of rubber solid) BR: BR150 manufactured by UBE Elastomer Co., Ltd. (butadiene rubber, cis content: 98 mol%, vinyl content: 1 mol%) CB (carbon black): Diablack I manufactured by Mitsubishi Chemical Corporation (N220, N2SA: 114m 2 / g, average primary particle size: 22 nm) Silica: Ultrasil VN3 manufactured by Evonik Degussa GmbH (N2SA: 175m 2 / g, average primary particle size: 18 nm) Coupling agent (silane coupling agent): Si266 manufactured by Evonik Degussa GmbH (bis(3-triethoxysilylpropyl) disulfide) Oil: Diana Process NH-70S manufactured by Idemitsu Kosan Co., Ltd. Resin 1: SYLVATARAXX 4150 manufactured by Kraton Corporation (polyt terpene resin, Mw: 2500, softening point: 115°C) Resin 2: Oppera PR383 manufactured by ExxonMobil Corporation (hydrogenated DCPD-C9 resin, containing styrene and cyclopentadiene as monomer components, Mw: 770, softening point: 103°C, styrene content: 1.78% by mass) Zinc oxide: Zinc white No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Antioxidant 1: Nocrac 6C (6PPD) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) Antioxidant 2: Nocrac RD manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. (poly(2,2,4-trimethyl-1,2-dihydroquinoline)) Stearic acid: Bead stearic acid Camellia manufactured by NOF Corporation Wax: Oz Ace 0355 manufactured by Nippon Seiro Co., Ltd. (paraffin wax) Sulfur: HK-200-5 (powder sulfur containing 5% oil) manufactured by Hosoi Chemical Industry Co., Ltd. Vulcanization accelerator 1: Nocceler D (1,3-diphenylguanidine (DPG)) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd. Vulcanization accelerator 2: Nocceler CZ (N-cyclohexyl-2-benzothiazolylsulfenamide (CBS)) manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

[0164] [Examples and Comparative Examples] Tires are manufactured according to the tire structures and compounding formulations shown in each table. First, using a 1.7 L closed Banbury mixer, chemicals other than sulfur and vulcanization accelerators are kneaded for 1 to 10 minutes until the discharge temperature reaches 150 to 160 °C to obtain a kneaded product. Next, using a twin-screw open roll, sulfur and vulcanization accelerators are added to the obtained kneaded product and kneaded for 4 minutes until the temperature reaches 105 °C to obtain an unvulcanized rubber composition. Using the obtained unvulcanized rubber composition, it is extruded into the shape of a cap tread using an extruder equipped with a die of a predetermined shape, and bonded together with other tire members to produce an unvulcanized tire. The obtained unvulcanized tire is press-vulcanized at 150 °C for 35 minutes to manufacture each test tire. Note that the tread portion is composed of a cap tread and a base tread, the thickness of the cap tread is 6 mm, and the thickness of the base tread is 4 mm.

[0165] [Evaluation] For each test tire, the results measured by the following method are described in the corresponding column of the table below. Each test tire is used after being in a normal state unless otherwise specified.

[0166] [Wet Grip Performance after Long-Term Use] Each test tire is mounted on each of the four wheels of a FF passenger car with a displacement of 2000 cc, and driven off-road for 10,000 km. Thereafter, on a wet asphalt road surface, the braking distance from the point where the brakes are applied at a speed of 100 km / h is measured. Taking the braking distance of the test tire of the reference comparative example (Comparative Example 2) as 100, the wet grip performance of each tire is expressed as an index according to the following calculation formula. The larger the index, the better the wet grip performance. (Wet grip performance index) = (Braking distance of the tire of the reference comparative example) / (Braking distance of each test tire) × 100

[0167]

Table 1

[0168] [Embodiment] Examples of embodiments of the present invention are shown below.

[0169] [1] A tire having a tread portion, The rubber layer of the tread portion is composed of a rubber composition containing at least one rubber selected from the group consisting of styrene-butadiene rubber and isoprene-based rubber, and a copolymer resin containing styrene and cyclopentadiene as monomer components. The maximum load capacity of the tire is W L (kg), the weight of the tire is G (kg), and when the mass of the rubber component is 100% by mass, when the total styrene amount (mass%) in the rubber composition is St, W L A tire in which G and St satisfy the following formulas (1) and (2), the right side of formula (1) is preferably 0.0144, more preferably 0.0142, and the right side of formula (2) is preferably 10, more preferably 20, still more preferably 30, still more preferably 100, still more preferably 900, still more preferably 950, still more preferably 990, still more preferably 1100, still more preferably 1200. (1) G / W L <0.0145 (2) St / (G / W L ) > 8 [2] The tire according to [1] above, wherein the right side of formula (1) is 0.140, preferably 0.139, more preferably 0.137. [3] The tire according to [1] above, wherein the right side of formula (1) is 0.135. [4] The tire according to any one of [1] to [3] above, wherein the rubber component contains butadiene rubber. [5] The tire according to any one of [1] to [3] above, wherein the rubber component contains butadiene rubber, styrene-butadiene rubber and isoprene-based rubber. [6] The tire according to any one of [1] to [5] above, wherein the rubber composition contains silica. [7] The rubber composition contains silica and carbon black, The content (parts by mass) of the silica with respect to 100 parts by mass of the rubber component is A SIL and the content (parts by mass) of the carbon black with respect to 100 parts by mass of the rubber component is A CB In the case of, A SIL / A CB is more than 1.0, preferably more than 2.0, more preferably more than 3.0, still more preferably more than 4.0, still more preferably more than 5.0, still more preferably more than 6.0. The tire according to any one of [1] to [6] above. [8] The tire according to any one of [1] to [7] above, wherein the copolymer resin is a DCPD-C9 resin.

Explanation of symbols

[0170] Wt Tire section width Ht Tire section height Dt Tire outer diameter

Claims

Claim 1 A tire comprising a tread portion, wherein the rubber layer of the tread portion is composed of a rubber composition containing a rubber component containing at least one rubber selected from the group consisting of styrene-butadiene rubber and isoprene-based rubber, and a copolymer resin containing styrene and cyclopentadiene as monomer components; The maximum load capacity of the tire is W L (kg), the weight of the tire is G (kg), and when the mass of the rubber component is 100% by mass, when the total styrene amount (% by mass) in the rubber composition is St, W L A tire in which W, G, and St satisfy the following formulas (1) and (2). (1) G / W L <0.0145 (2) St / (G / W L ) > 8

2. The tire according to claim 1, wherein the right side of formula (1) is 0.

140.

3. The tire according to claim 1, wherein the right side of formula (1) is 0.

135.

4. The tire according to any one of claims 1 to 3, wherein the rubber component contains butadiene rubber.

5. The tire according to any one of claims 1 to 3, wherein the rubber component contains butadiene rubber, styrene-butadiene rubber and isoprene-based rubber.

6. The tire according to any one of claims 1 to 3, wherein the rubber composition contains silica.

7. The rubber composition contains silica and carbon black, The content (parts by mass) of the silica with respect to 100 parts by mass of the rubber component is A SIL and the content (parts by mass) of the carbon black with respect to 100 parts by mass of the rubber component is A CB In the case where it is A SIL / A CB is more than 1.0, the tire according to any one of claims 1 to 3

8. The tire according to any one of claims 1 to 3, wherein the copolymer resin is a DCPD-C9 resin.

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