Tire

Abstract

The present invention provides a tire capable of improving the overall performance of steering stability performance and wet grip performance. A tire provided with a tread section comprising a rubber composition, and a belt layer provided on the inside of the tread section in the radial direction of the tire, the belt layer comprising belt cords comprising filaments comprising polyester fibers, the rubber composition contains a rubber component containing a styrene-butadiene rubber and / or an isoprene rubber and a copolymer resin containing styrene and cyclopentadiene as monomer components, and the cord diameter of the belt cord is D (mm). When the total amount of styrene in the rubber composition is S (mass%) when the mass of the rubber component is 100 mass%, D * S is greater than 0.05.

Description

Technical Field

[0001] The present invention relates to a tire. Background Art

[0002] To date, various studies have been conducted on methods for improving handling stability and wet grip performance (for example, see Patent Documents 1 and 2). However, in recent years, further improvement in these performances has been required. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-544936 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-186567 Summary of the Invention [Problems to be Solved by the Invention]

[0004] An object of the present invention is to provide a tire capable of achieving an improvement in the comprehensive performance of handling stability and wet grip performance. [Means for Solving the Problems]

[0005] The present invention relates to a tire including a tread surface portion and a band layer existing on the radially inner side of the tread surface portion, wherein the band layer has band cords including filaments formed of polyester fibers, the tread surface portion is composed of a rubber composition, the rubber composition contains a rubber component including styrene-butadiene rubber and / or isoprene-based rubber and a copolymer resin including styrene and cyclopentadiene as monomer components, when the cord diameter of the band cords is D (mm) and the total styrene amount in the rubber composition when the mass of the rubber component is 100% by mass is S (% by mass), D×S is greater than 0.05. [Effects of the Invention]

[0006] According to the present invention, a tire capable of achieving an improvement in the comprehensive performance of handling stability and wet grip performance can be provided. Brief Description of the Drawings

[0007] Figure 1 is a cross-sectional view of a tire according to an embodiment of the present invention. Figure 2 is a perspective view of a ply forming the band layer. Figure 3 is a cross-sectional view of one band cord. [Reference Numerals] 1: Tread surface portion 2: Sidewall portion 4: Carcass 5: Belt layer​​​ 6: Belt layer 7: Inner liner 11: Layer forming the tread surface of the outer surface (tread rubber layer) 12: Base rubber layer 15: Circumferential groove 16: Tread surface 31: Belt cord 32: Skim rubber 33: Yarn 34: Filament d: Filament diameter D1: Major axis of the belt cord D2: Minor axis of the belt cord CL: Tire equator Detailed implementation mode

[0008] The tire according to an embodiment of the present invention is a tire having a tread portion and a belt layer existing on the radially inner side of the tread portion, wherein the belt layer has a belt cord containing filaments formed of polyester fibers, the tread portion is composed of a rubber composition, the rubber composition contains a rubber component containing styrene-butadiene rubber and / or isoprene rubber and a copolymer resin containing styrene and cyclopentadiene as monomer components, when the cord diameter of the belt cord is D (mm) and the total styrene amount in the rubber composition when the mass of the rubber component is 100% by mass is S (% by mass), D×S is greater than 0.05.

[0009] Although not wishing to be bound by theory, as a mechanism for improving the comprehensive performance of handling stability and wet grip performance in the tire of the present invention, for example, it can be considered as follows.

[0010] (1) The copolymer resin containing styrene and cyclopentadiene as monomer components has high compatibility with styrene-butadiene rubber and isoprene rubber and is large in volume. Therefore, the rubber composition containing it does not impair the reinforcing effect and imparts softness, and thus contributes to the improvement of wet grip performance.

[0011] In addition, (2) by making the product (D×S) of the cord diameter D of the belt cord and the total styrene amount S in the rubber composition greater than a specified value, the handling stability and wet grip performance can be improved.

[0012] Through the synergistic action of the above (1) and (2), an excellent effect of improving the comprehensive performance of handling stability and wet grip performance can be achieved.

[0013] As the polyester fiber, recycled polyester fiber is preferably used.

[0014] When the complex elastic modulus of the rubber composition at 30°C is 30°C E* (MPa), 30°C E* × D is preferably 3.0 or more. By setting 30°C E* × D within the above range, the effects of the present invention can be exerted.

[0015] From the perspective of wet grip performance, the tanδ (0°C tanδ) of the rubber composition at 0°C is preferably 0.45 or more.

[0016] Relative to 100 parts by mass of the rubber component, the rubber composition preferably contains 60 parts by mass or more of silica. By containing 60 parts by mass or more of silica, the followability to the road surface is improved through the interaction between the silanol groups of silica and the moisture on the road surface, which contributes to the improvement of wet grip performance.

[0017] From the perspective of wet grip performance, in the rubber composition, relative to 100 parts by mass of the rubber component, the content of the copolymer resin is preferably 10 parts by mass or more.

[0018] From the perspective of handling stability, the distance G from the tread surface to the belt cord is preferably 12.0 mm or less.

[0019] [Definition] The "tread part" is a component including the part forming the ground contact surface of the tire. In the tire radial cross-section, when there are components such as a belt layer, a belt reinforcing layer, and a carcass layer that form the tire skeleton made of steel or textile materials, it is a component arranged more radially outside than them.

[0020] A "filament" refers to the smallest unit forming a cord. A yarn is formed by twisting multiple such filaments together.

[0021] The "rubber component of the rubber composition" refers to the component that contributes to crosslinking in the rubber composition, and generally has a weight average molecular weight (Mw) of 10,000 or more.

[0022] The "total styrene amount S in the rubber composition" refers to the total styrene amount (mass%) in the rubber composition when the mass of the rubber component is 100 mass%, and is the total amount of the styrene part contained in the rubber component and the styrene part contained in the compounding agents other than the rubber component. As the styrene part, any group having a styrene structure can be used, and there is no particular limitation. For example, styrene, α-methylstyrene, vinyltoluene, chlorostyrene, etc. can be cited.

[0023] That is, first, for each rubber component, the value obtained by multiplying the content (mass %) of the styrene portion by the mass fraction in the rubber component is calculated, and these values are added together to obtain a total value (mass %). Next, for the compounding agents containing a styrene portion other than the rubber components contained in the rubber composition, the value obtained by multiplying the content (mass %) of the styrene portion of each compounding agent containing a styrene portion by the mass fraction relative to 100 parts by mass of the rubber component is calculated, and these values are added together to obtain a total value (mass %). The value obtained by adding the two total values is taken as the total styrene amount S (mass %). Therefore, it is calculated by {∑(content (mass %) of the styrene portion of each rubber containing a styrene portion × content (mass %) in the rubber component of each rubber containing a styrene portion / 100) + ∑(content (mass %) of the styrene portion of each compounding agent containing a styrene portion other than the rubber component × compounding amount (parts by mass) of each compounding agent containing a styrene portion relative to 100 parts by mass of the rubber component / 100)}. It should be noted that in this specification, when the "styrene portion" is styrene (for example, when the rubber containing a styrene portion is styrene-butadiene rubber), the "content of the styrene portion" is sometimes referred to as the "styrene content".

[0024] 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 in the rubber composition, in addition to this rubber component, 20 parts by mass of the first resin having a styrene portion (styrene content: 5 mass%) and 10 parts by mass of the second resin having a styrene portion (styrene content: 1 mass%) are further contained relative to 100 parts by mass of the rubber component, the total styrene amount 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)}.

[0025] The "normal state" means a load-free state in which the rim is assembled on a normal rim and filled with air at a normal internal pressure.

[0026] "Normal rim" means the rim specified for each tire in the specification system including the specifications on which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Manufacturers Association), it means the standard rim in the applicable sizes described in "JATMA YEARBOOK"; in the case of ETRTO (The European Tyre and Rim Technical Organisation), it means the "Measuring Rim" described in "STANDARDS MANUAL"; in the case of TRA (The Tire and Rim Association, Inc.), it means the "Design Rim" described in "YEAR BOOK". The references are made in the order of JATMA, ETRTO, and TRA, and if there are applicable sizes, the specifications thereof shall be followed. It should be noted that in the case of a tire not specified in the above-mentioned specifications, it means the rim with the smallest diameter and the narrowest rim width among the rims that can be assembled on the tire and maintain the internal pressure (i.e., no air leakage occurs between the rim and the tire).

[0027] "Normal internal pressure" means the air pressure specified for each tire in the specification system including the specifications on which the tire is based. In the case of JATMA, it means the "maximum air pressure"; in the case of ETRTO, it means the "INFLATION PRESSURE"; in the case of TRA, it means the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". Similar to the case of the normal rim, the references are made in the order of JATMA, ETRTO, and TRA, and if there are applicable sizes, the specifications thereof shall be followed. It should be noted that in the case of a tire not specified in the above-mentioned specifications, it means the normal internal pressure (wherein, 250 KPa or more) of other tire sizes described with the above-mentioned normal rim as the standard rim (provided that they are tire sizes specified in the specifications). In the case where there are multiple normal internal pressures of 250 kPa or more, it means the minimum value among them.

[0028] "Normal load" means the load specified for each tire in the specification system including the specification on which the tire is based. For example, in the case of JATMA, it means "maximum load capacity"; in the case of ETRTO, it means "load capacity"; in the case of TRA, it means the maximum value recorded in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". Similar to the case of the normal rim and normal internal pressure, references are made in the order of JATMA, ETRTO, and TRA, and if there are applicable dimensions during the reference, the specifications thereof shall be followed. Moreover, in the case of a tire not specified in the above specifications, the maximum load capacity W obtained by separate calculation shall be used L as the normal load.

[0029] "Maximum load capacity W L " is calculated by the following formula. "V" is the imaginary volume of the tire (mm 3 ), "Dt" is the outer diameter of the tire in the normal state (mm), "Ht" is the sectional height of the tire in the radial direction of the tire in the section of the tire based on the plane including the tire rotation axis (mm), and "Wt" is the sectional width of the tire in the normal state (mm). Regarding Ht, when the rim diameter of the tire is set as R, it can be obtained by (Dt - R) / 2. Regarding Wt, in the case where there are patterns, characters, etc. on the tire sidewall, it is the value obtained after removing them. It should be noted that the maximum load capacity is synonymous with the above normal load.

[0030]

Formula 1

[0031] Regarding "the dimensions of each part of the tire", unless otherwise specified, the dimensions appearing on the outer surface of the tire are the values determined in the normal state, and the dimensions existing inside the tire or on the tire cross-section are the values determined in the state where the tire is cut by the plane including the tire rotation axis and the cut tire piece is held at the rim width of the normal rim.

[0032] "The distance G from the tread surface to the belt cord" means the straight-line distance from the crown portion on the tire equatorial plane to the outermost part of the tire in the radial direction of the belt cord in a cross-section of the tire cut by a plane including the tire rotation axis. Regarding the "crown portion", when there is no circumferential groove on the tire equatorial plane, it means the outermost end in the radial direction of the tread surface intersecting the tire equatorial plane; when there is a circumferential groove on the tire equatorial plane, it means the part where the line segment connecting the outermost ends of the tread in the land portion connecting the two ends of the circumferential groove intersects the tire equatorial plane.

[0033] "30℃ E*" is the complex elastic modulus measured under the conditions of a temperature of 30℃, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain of ±1%, and a tensile mode using a dynamic viscoelasticity measuring device (for example, the EPLEXOR series manufactured by GABO). The sample for this measurement is a vulcanized rubber composition with a length of 20 mm × a width of 4 mm × a thickness of 1 mm. When cut out from a tire, it is cut out from the tread surface with the tire circumferential direction as the long side and the tire radial direction as the thickness direction.

[0034] "0℃ tanδ" is the loss tangent measured under the conditions of a temperature of 0℃, a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±2.5%, and a tensile mode using a dynamic viscoelasticity measuring device (for example, the EPLEXOR series manufactured by GABO). The sample for this measurement is made in the same way as in the case of 30℃ E*.

[0035] "The content of the styrene part" is calculated by thermal decomposition gas chromatography. It should be noted that in this specification, "thermal decomposition gas chromatography" refers to a method of heating a sample using a thermal decomposition device, separating each component contained in the gas components generated by this heating using a separation chromatographic column, and analyzing the separated components.

[0036] "The vinyl content (the amount of 1,2-bonded butadiene units)" is calculated by thermal decomposition gas chromatography in the same way as the above-mentioned content of the styrene part.

[0037] "The glass transition temperature Tg" is a value obtained by differential scanning calorimetry (DSC) according to JIS K 7121, for example, applicable to SBR. For example, when SBR contains a filler oil, according to JIS K 6229, the sample after removing the filler oil using acetone is measured.

[0038] "The cis content (the amount of cis-1,4-bonded butadiene units)" is a value calculated by infrared absorption spectroscopy according to JIS K 6239-2:2017, for example, applicable to rubber components having repeating units derived from butadiene such as BR.

[0039] "Weight-average molecular weight (Mw)" can be determined by conversion to standard polystyrene based on the measured values obtained by gel permeation chromatography (GPC) (e.g., GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKgel SuperMultipore HZ-M manufactured by Tosoh Corporation). For example, it is applicable to SBR, BR, etc.

[0040] "Nitrogen adsorption specific surface area of carbon black (N2SA)" is measured according to JIS K 6217-2:2017.

[0041] "Nitrogen adsorption specific surface area of silica (N2SA)" is measured by the BET method according to ASTM D 3037-93.

[0042] "Average primary particle size" is a value obtained by taking arithmetic mean of the particle sizes of 400 particles by photographing particle images with a transmission or scanning electron microscope. In the case where the shape of the particle is spherical, the diameter of the sphere is taken as the particle size, and in the case where the shape of the particle is other than spherical, the equivalent circle diameter (positive square root of {4×(area of the particle) / π}) is calculated from the microscope image as the particle size. The average primary particle size is applicable to silica, carbon black, etc.

[0043] "Softening point of resin" is the softening point specified in JIS K 6220-1:2015 7.7 measured with a ring-and-ball softening point apparatus, the temperature at which the ball drops.

[0044] "Plasticizer" refers to a material that imparts plasticity to the rubber component, and is a component extracted from the rubber composition using acetone. In addition, plasticizers include plasticizers that are liquid (in liquid state) at 25°C and plasticizers that are solid at 25°C. Among them, plasticizers do not include waxes and stearic acid commonly used in the tire industry.

[0045] "Content of plasticizer" also includes the amount of plasticizer contained in the rubber component with increased plasticizer content pre-increased by plasticizer such as oil, resin component, liquid rubber component, etc. In addition, the same applies to the content of oil, resin component, and liquid rubber component. For example, when the increment component is oil, the filling oil is included in the content of oil.

[0046] Hereinafter, a method for manufacturing a tire according to an embodiment of the present invention will be described in detail. However, the following description is for illustrative purposes of the present invention and is not intended to limit the technical scope of the present invention to this description.

[0047] [Tire] Hereinafter, a tire according to an embodiment of the present invention will be described with reference to the drawings.

[0048] Hereinafter, the tire of the present embodiment will be described with reference to the accompanying drawings. It should be noted that the following-described embodiment is merely an example, and the tire of the present embodiment is not limited to the following embodiment.

[0049] Figure 1 The tire of the present embodiment is illustrated. Figure 1 It shows a part of the cross-section when the tire is cut by a plane including the tire rotation axis. Figure 1 In this figure, the up-down direction is the radial direction of the tire, the left-right direction is the axial direction of the tire, and the direction perpendicular to the paper surface is the circumferential direction of the tire. Figure 1 In this figure, the dash-dot line CL represents the tire equator.

[0050] As Figure 1 shown, on the radially inner side of the tread surface 1 of the tire, there are a belt layer 6 and a belt ply 5. The belt ply 5 is laminated in two layers, and the belt layer 6 is disposed between the tread surface 1 and the belt ply 5. The belt layer 6 includes an edge belt 6b that only covers the edge portion of the belt ply 5 and a full belt 6a that covers the entire area of the belt ply 5. Below the belt ply 5, a carcass 4 and an inner liner 7 are laminated.

[0051] The tread surface of the present embodiment may be a tread surface composed of a single rubber layer, or may be a tread surface having a layer (tread rubber layer) that forms the tread surface 16 on the outer surface and one or more rubber layers (inner rubber layers) existing between the tread rubber layer and the belt layer 6. Figure 1 In this figure, there are a tread rubber layer 11 and a base rubber layer 12 laminated on the radially outer side of the belt layer 6.

[0052] In this specification, the "rubber composition constituting the tread surface" refers to the rubber composition constituting the tread rubber layer when the tread surface is composed of two or more layers.

[0053] Figure 2 In this figure, a perspective view of the cord layer forming the belt layer 6 is shown. As Figure 2 shown, a plurality of belt cords 31 are covered with skim rubber 32. As long as at least one of the edge belt 6b or the full belt 6a has a belt cord containing filaments formed of polyester fiber, it is preferable that the full belt 6a has it.

[0054] The belt cords 31 are wound spirally in the circumferential direction of the tire. The angle of the belt cords with respect to the circumferential direction of the tire can be, for example, 15° or less, 10° or less, 5° or less. Since the belt ply 5 is constrained by these belt cords, it is possible to suppress the increase in the outer diameter of the tire due to the internal pressure during driving.

[0055] Figure 3 In this figure, a cross-sectional view of one cord 31 is shown. As Figure 3As shown, the belt cord 31 is formed by twisting a plurality of filaments 34 each having an outer diameter d. Preferably, the belt cord 31 is formed by twisting a yarn 33 formed by twisting a plurality of filaments 34. Figure 3 In Figure 3 , since the belt cord 31 is formed by twisting two yarns 33, a part 33a of the outer surface of the yarn 33 (corresponding to the contact surface of the two yarns 33) is flattened. As a result, the cross-sectional shape of the belt cord 31 is a substantially elliptical shape with a reduced cross-sectional width at the central portion. However, the belt cord of the present embodiment is not limited to such a manner.

[0056] The cord diameter D of the belt cord 31 is obtained by a simple average of the major axis D1 and the minor axis D2 in the cross-section of the belt cord 31. The major axis D1 refers to the maximum diameter of the belt cord 31. The minor axis D2 refers to the maximum diameter among the diameters of the belt cord 31 in the direction orthogonal to the major axis D1.

[0057] The belt cord 31 preferably extends in the length direction of the belt cord 31 with a certain cross-sectional shape, but the cross-sectional shape and cross-sectional area of the belt cord 31 may vary in the length direction of the cord 31. At this time, the cord diameter D is preferably measured at the position where the cross-sectional area of the belt cord 31 is the smallest. This is because the substantial basic tensile strength depends on the structure of the cord at the position where the cross-sectional area of the cord becomes the smallest.

[0058] From the viewpoint of handling stability, the cord diameter D of the belt cord 31 is preferably 0.40 mm or more, more preferably 0.45 mm or more, and further preferably 0.50 mm or more. On the other hand, from the viewpoint of low fuel consumption performance, the cord diameter D is preferably 0.90 mm or less, more preferably 0.80 mm or less, further preferably 0.75 mm or less, and particularly preferably 0.70 mm or less.

[0059] From the viewpoint of handling stability, the distance G from the tread surface 16 to the belt cord 31 is preferably 12.0 mm or less, more preferably 11.0 mm or less, further preferably 10.0 mm or less, and particularly preferably 9.0 mm or less. In addition, from the viewpoint of ensuring the thickness of the tread portion, this distance is preferably 3.0 mm or more, more preferably 4.0 mm or more, further preferably 5.0 mm or more, and particularly preferably 6.0 mm or more.

[0060] The belt cord 31 includes filaments formed of polyester fiber, and may further include filaments formed of other materials.

[0061] The polyester fiber can be obtained, for example, by spinning a polyester obtained by a known method by the following method.

[0062] The polyester can be obtained by known methods. For example, it can be obtained by polycondensing a diol and a dicarboxylic acid or its derivative in the presence of a commonly used catalyst as required.

[0063] The diol is not particularly limited, and aliphatic diols having 2 to 6 carbon atoms are preferred. Specifically, for example, ethylene glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol, cyclohexanediol, etc. can be cited. Among them, ethylene glycol, propylene glycol, and butylene glycol are preferred, and ethylene glycol is more preferred.

[0064] As the dicarboxylic acid, for example, aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, and aromatic dicarboxylic acids can be cited, and aromatic dicarboxylic acids are preferred.

[0065] The aliphatic dicarboxylic acid is not particularly limited, and aliphatic straight-chain dicarboxylic acids having 2 to 20 carbon atoms are preferred. Specifically, for example, adipic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, etc. can be cited. Among them, adipic acid, sebacic acid, and dodecanedioic acid are preferred.

[0066] The alicyclic dicarboxylic acid is not particularly limited. For example, 1,4-cyclohexanedicarboxylic acid, dicyclohexylmethane-4,4'-dicarboxylic acid, norbornanedicarboxylic acid can be cited.

[0067] The aromatic dicarboxylic acid is not particularly limited. For example, phthalic acid compounds such as isophthalic acid, terephthalic acid, and phthalic acid, naphthalenedicarboxylic acid, diphenylmethanedicarboxylic acid, 2,5-furandicarboxylic acid, etc. can be cited. Among them, terephthalic acid, naphthalenedicarboxylic acid, and 2,5-furandicarboxylic acid are preferred, and terephthalic acid is more preferred.

[0068] As the derivative of the dicarboxylic acid, the ester of the dicarboxylic acid is preferred. As the ester, an alkyl ester having 1 to 4 carbon atoms is preferred.

[0069] The polyester is not particularly limited. Specifically, for example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene furanoate (PEF), polytrimethylene terephthalate, polybutylene terephthalate, polybutylene naphthalate, etc. can be cited. PET and PEN are preferred, and PET is more preferred. With respect to all the constituent units, the content of isophthalic acid in PET is preferably less than 10 mol%, more preferably less than 1 mol%, and further preferably less than 0.1 mol%.

[0070] Within the range not impairing the effects of the present invention, the polyester may contain other monomers in addition to the diol and the dicarboxylic acid. With respect to all the constituent units, the content of the other monomers is preferably less than 10 mol%, more preferably less than 5 mol%, and further preferably less than 1 mol%.

[0071] Alternatively, the polyester may be a high-molecular-weight polyester obtained by chain-extending (coupling) these copolyesters. Examples of the chain extender include carbonate compounds, diisocyanate compounds, and the like.

[0072] The polyester fiber of the present embodiment may be a recycled polyester fiber or a biomass polyester fiber.

[0073] Recycled polyester refers to polyester obtained from used polyester articles. Examples of recycled polyester include mechanically recycled polyester and chemically recycled polyester.

[0074] Mechanically recycled polyester refers to polyester obtained by crushing and cleaning used polyester articles to remove contaminants and foreign substances to obtain flakes, and further treating the flakes under high temperature and reduced pressure. It should be noted that the washed flakes can be granulated by a known method and then treated under high temperature and reduced pressure. In mechanical recycling, since recycled polyester can be obtained without chemical decomposition, there is a tendency for the cost to be lower than that of chemical recycling.

[0075] Chemically recycled polyester refers to polyester obtained by chemically decomposing the flakes back to monomer units, refining them, and then repolymerizing them. In chemical recycling, polyester with physical properties and characteristics not inferior to those of virgin polyester manufactured by the conventional method from dicarboxylic acids and diols using petroleum and the like as raw materials can be obtained.

[0076] In the cleaning process of the flakes, from the perspective of cleaning effect, alkali cleaning can be performed using an aqueous sodium hydroxide solution or the like. The concentration of the alkaline aqueous solution depends on temperature, time, and stirring state, and is usually in the range of 1 to 10% by weight. In addition, the cleaning time required is in the range of 10 to 100 minutes, and in order to improve the effect, it is preferably cleaned while stirring. In addition, in the case of performing alkali cleaning, it is preferably followed by rinsing cleaning.

[0077] In mechanical recycling, the following situation may sometimes occur: due to the alkali cleaning or heating in each treatment process, the degree of polymerization of the polyester decreases, and the formability, strength, heat resistance, etc. of the polyester decrease. In such a case, in order to restore the decreased degree of polymerization, preferably, the flakes are continuously solid-phase polymerized in an inert gas such as nitrogen or noble gas at 180 to 245 °C, preferably 200 to 240 °C, or the flakes are melted and granulated.

[0078] The chemical decomposition (depolymerization) of the polyester in chemical recycling can be carried out by a known method. For example, it can be carried out by mixing the flakes with an alkylene glycol such as ethylene glycol and / or methanol while heating in the presence of a commonly used catalyst as needed.

[0079] A biomass polyester refers to a polyester obtained from a raw material containing monomers derived from biomass. Therefore, a biomass polyester contains monomer units derived from biomass.

[0080] In the production of a biomass polyester, monomers derived from fossil fuels can be used together with monomers derived from biomass. That is, in a biomass polyester, in addition to containing monomer units derived from biomass, it may also contain monomer units derived from fossil fuels.

[0081] Monomers derived from biomass can be directly produced from biomass-derived raw materials by extraction or fermentation methods, or the products obtained by extraction or fermentation methods can be transformed through chemical reactions. In addition, commercially available monomers derived from biomass can be used. Examples of monomers derived from biomass include diols derived from biomass and dicarboxylic acids derived from biomass.

[0082] As the filaments constituting the belt cord, as filaments that can be used in addition to polyester fibers, organic fibers are preferred. Examples of organic fibers include nylon fibers, aramid fibers, polyketone fibers, poly(phenylene vinylene acrylate) fibers, polyacrylate fibers, rayon fibers, cellulose fibers, carbon fibers, etc. These fibers can be formed from synthetic fibers, fibers derived from biomass, recycled / reclaimed fibers, etc.

[0083] When the belt cord contains the above-mentioned other materials in addition to polyester fibers, the belt cord can be any of the following cords: a hybrid cord obtained by twisting a yarn obtained by twisting filaments formed from polyester fibers and a yarn obtained by twisting filaments formed from other materials; a cord using a yarn having multifilaments obtained by twisting each filament; a cord having a chemical structure in which each component is chemically bonded.

[0084] The content of polyester fibers in the belt cord is preferably 10% by mass or more, more preferably 30% by mass or more, further preferably 50% by mass or more, further preferably 60% by mass or more, further preferably 70% by mass or more, and particularly preferably 80% by mass or more. On the other hand, the upper limit value of this content is not particularly limited. That is, the belt cord may contain only filaments formed from polyester fibers.

[0085] From the perspective of ensuring good adhesion to the cover layer, the belt cord is preferably treated with a pre-coated adhesion layer. As the adhesion layer, a known adhesion layer can be used. For example, in addition to the treatment using resorcinol·formalin·rubber latex (RFL), an adhesion layer obtained by performing an epoxy treatment with an adhesive composition containing sorbitol polyglycidyl ether and blocked isocyanate and then performing an RFL treatment, an adhesion layer obtained by treating with an adhesive composition containing a haloalcohol compound, a blocked isocyanate compound, and rubber latex, etc. can also be used.

[0086] In the direction orthogonal to the longitudinal direction of the belt cord 31, the number of belt cords 31 arranged per 50 mm width, E (also referred to as the cord density (ends)), is preferably 30 or more, more preferably 35 or more, still more preferably 40 or more, and particularly preferably 45 or more. In addition, the number of arranged cords E is preferably 70 or less, more preferably 65 or less, still more preferably 60 or less, and particularly preferably 55 or less.

[0087] Figure 2 and Figure 3 In, one belt cord 31 is composed of two yarns 33, but it is not limited to such a manner. The fineness of the yarn is preferably 500 dtex or more, more preferably 700 dtex or more, still more preferably 800 dtex or more, and particularly preferably 1000 dtex or more. In addition, the fineness of the yarn is preferably 3500 dtex or less, more preferably 3000 dtex or less.

[0088] The total fineness of the belt cord is preferably 1000 dtex or more, preferably 1400 dtex or more, still more preferably 1600 dtex or more, and particularly preferably 2000 dtex or more. In addition, the total fineness of the belt cord is preferably 7000 dtex or less, more preferably 6500 dtex or less, still more preferably 6000 dtex or less.

[0089] From the perspective of handling stability performance, the breaking strength of the belt cord is preferably 3.5 cN / dtex or more, more preferably 4.0 cN / dtex or more, still more preferably 4.5 cN / dtex or more, still more preferably 5.0 cN / dtex or more, still more preferably 5.5 cN / dtex or more, and particularly preferably 6.0 cN / dtex or more. It should be noted that the upper limit value of the breaking strength is not particularly limited.

[0090] From the perspective of the effects of the present invention, when the mass of the rubber component is 100% by mass, the total styrene amount S in the rubber composition is preferably 0.1% by mass or more, more preferably 1% by mass or more, still more preferably 2% by mass or more, still more preferably 4% by mass or more, still more preferably 6% by mass or more, still more preferably 8% by mass or more, and particularly preferably 10% by mass or more. In addition, from the perspective of low fuel consumption performance, the total styrene amount is preferably 42% by mass or less, more preferably 38% by mass or less, still more preferably 34% by mass or less.

[0091] It should be noted that the total styrene content S in the rubber composition can be appropriately adjusted according to the type or compounding amount of the rubber components described later. For example, by increasing the compounding amount of styrene-butadiene rubber, compounding styrene-butadiene rubber with a high styrene content, compounding a resin containing styrene as a monomer component, etc., the total styrene content S can be increased. Conversely, by reducing the compounding amount of styrene-butadiene rubber, etc., the total styrene content S can be reduced.

[0092] From the perspective of the effects of the present invention, the tanδ at 0 °C of the rubber composition is preferably 0.40 or more, more preferably 0.45 or more, further preferably 0.50 or more, and particularly preferably 0.55 or more. On the other hand, from the perspective of low fuel consumption performance, it is preferably 1.00 or less, more preferably 0.95 or less, further preferably 0.90 or less, and particularly preferably 0.85 or less.

[0093] From the perspective of exerting resilience to deformation and improving responsiveness, the E* at 30 °C of the rubber composition is preferably 4.0 MPa or more, more preferably 4.5 MPa or more, further preferably 5.0 MPa or more, and particularly preferably 5.5 MPa or more. On the other hand, from the perspective of road surface followability, it is preferably 30 MPa or less, more preferably 25 MPa or less, further preferably 20 MPa or less, further preferably 15 MPa or less, and particularly preferably 10 MPa or less.

[0094] It should be noted that the tanδ at 0 °C and the E* at 30 °C of the rubber composition can be appropriately adjusted according to the types and compounding amounts of the rubber components, fillers, plasticizers, etc. described later. For example, the tanδ at 0 °C can be increased by increasing the total styrene content S in the rubber composition, increasing the content of a copolymer resin containing styrene and cyclopentadiene as monomer components, etc.

[0095] From the perspective of the effects of the present invention, D×S is greater than 0.05, preferably greater than 0.30, more preferably greater than 1.0, further preferably greater than 3.0, and particularly preferably greater than 5.0. On the other hand, from the perspective of low fuel consumption performance, D×S is preferably less than 30.0, more preferably less than 27.0, further preferably less than 25.0, and particularly preferably less than 23.0.

[0096] From the perspective of the effects of the present invention, 30 °C E*×D is preferably 3.0 or more, more preferably 3.5 or more, and further preferably 4.0 or more. On the other hand, from the perspective of low fuel consumption performance, 30 °C E*×D is preferably 7.0 or less, more preferably 6.0 or less, further preferably 5.0 or less, and particularly preferably 4.5 or less.

[0097] [Rubber Composition] The rubber composition constituting the tread surface of the present embodiment (hereinafter referred to as the rubber composition of the present embodiment) contains a rubber component including styrene-butadiene rubber and / or isoprene-based rubber, and a copolymer resin including styrene and cyclopentadiene as monomer components, and can all be manufactured using the raw materials described below. Hereinafter, the rubber composition of the present embodiment will be described.

[0098] <Rubber component> The rubber composition of the present embodiment preferably uses a diene-based rubber as the rubber component. As the diene-based rubber, for example, isoprene-based rubber, butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene rubber (SIR), styrene-isoprene-butadiene rubber (SIBR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), etc. can be cited. These diene-based rubbers can be modified rubbers treated with a modifying group that can interact with fillers such as carbon black and silica, or can be hydrogenated rubbers in which a part of the unsaturated bonds has been hydrogenated. The diene-based rubber can be used alone or in combination of two or more. In addition, as the diene-based rubber, an extended rubber pre-extended with a plasticizer described later can be used.

[0099] The content of the diene-based rubber in the rubber component is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and particularly preferably 95% by mass or more. In addition, the rubber component can be composed only of the diene-based rubber.

[0100] The rubber component of the present embodiment contains styrene-butadiene rubber and / or isoprene-based as essential components. The rubber component preferably contains SBR, more preferably contains SBR and isoprene-based rubber and / or BR, still more preferably contains SBR and isoprene-based rubber, and particularly preferably contains SBR, BR and isoprene-based rubber. In addition, the rubber component can be composed only of SBR, BR and isoprene-based rubber.

[0101] (SBR) As SBR, there is no particular limitation. For example, unmodified solution-polymerized SBR (S-SBR) or emulsion-polymerized SBR (E-SBR), modified SBRs of these (modified S-SBR, modified E-SBR), etc. can be cited. As the modified SBR, SBR modified at the terminal and / or main chain, modified SBR coupled with tin, silicon compounds, etc. (condensates, modified SBRs having a branched structure, etc.) can be cited. In addition, hydrides of these SBRs (hydrogenated SBRs) etc. can also be used. These SBRs can be used alone or in combination of two or more.

[0102] From the perspective of the effects of the present invention, the styrene content of the SBR is preferably 15% by mass or more, more preferably 19% by mass or more, further preferably 23% by mass or more, and particularly preferably 27% by mass or more. On the other hand, the styrene content of the SBR is preferably less than 60% by mass, more preferably less than 50% by mass, and further preferably less than 45% by mass. When the styrene content of the SBR is greater than 60% by mass, the styrene groups are adjacent, the polymer becomes too hard, and the crosslinking easily becomes uneven, which may deteriorate the blow performance during high-temperature driving. In addition, the temperature dependence increases, and the performance change with respect to temperature change becomes larger, and there is a tendency that the stable grip performance during driving and in the later stage cannot be obtained well. It should be noted that in this specification, the styrene content of the SBR is measured by the above-mentioned measurement method.

[0103] The vinyl content of the SBR is preferably greater than 10 mol%, more preferably greater than 15 mol%, and further preferably greater than 20 mol%. In addition, the vinyl content of the SBR is preferably less than 70 mol%, more preferably less than 65 mol%, and further preferably less than 60 mol%. It should be noted that in this specification, the vinyl content of the SBR is measured by the above-mentioned measurement method.

[0104] From the perspective of wet grip performance, the glass transition temperature (Tg) of the SBR is preferably greater than -80 °C, more preferably greater than -75 °C, and further preferably greater than -65 °C. In addition, from the perspective of low fuel consumption performance, the Tg of the SBR is preferably -40 °C or lower, more preferably -45 °C or lower, further preferably -50 °C or lower, and particularly preferably -55 °C or lower.

[0105] The weight average molecular weight (Mw) of the SBR is preferably greater than 200,000, more preferably greater than 300,000, further preferably greater than 400,000, and particularly preferably greater than 500,000. In addition, from the perspective of crosslinking uniformity, etc., the Mw is preferably less than 2,000,000, more preferably less than 1,500,000, and further preferably less than 1,000,000. It should be noted that the Mw of the SBR is measured by the above-mentioned measurement method.

[0106] As the SBR, oil-extended SBR or non-oil-extended SBR can be used. In this specification, as the SBR, commercially available products from JSR Corporation, Sumitomo Chemical Co., Ltd., UBE Industries, Ltd., Asahi Kasei Corporation, ZS Elastomer Co., Ltd., ARLANXEO Corporation, etc. can be used.

[0107] The content of SBR in the rubber component can be appropriate so that D×S is within the above range, preferably 10% by mass or more, more preferably 30% by mass or more, still more preferably 50% by mass or more, still more preferably 60% by mass or more, still more preferably 70% by mass or more. Particularly preferably 75% by mass or more. On the other hand, the upper limit value of the content is not particularly limited. For example, it can be set to 99% by mass or less, 95% by mass or less, 90% by mass or less, 85% by mass or less.

[0108] (Isoprene rubber) As the isoprene rubber, there is no particular limitation. For example, natural rubber (NR), isoprene rubber (IR), modified natural rubber, etc. can be cited. As NR, for example, SIR20, RSS#3, TSR20, etc. can be cited. As IR, for example, IR2200, etc. can be cited. As the modified natural rubber, for example, epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), high-purity natural rubber, grafted natural rubber, etc. can be cited. These isoprene rubbers can be used alone or in combination of two or more.

[0109] The content of the isoprene rubber in the rubber component is preferably 70% by mass or less, more preferably 60% by mass or less, still more preferably 50% by mass or less, particularly preferably 40% by mass or less. On the other hand, the lower limit value of this content is not particularly limited. For example, it can be 1% by mass or more, 3% by mass or more, 5% by mass or more, 7% by mass or more.

[0110] (BR) As BR, there is no particular limitation. 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 series butadiene rubber synthesized using a rare-earth element-based catalyst (rare-earth series BR), BR containing syndiotactic polybutadiene crystals (BR containing SPB), modified BR (high-cis modified BR, low-cis modified BR), etc., which are conventional products in the tire industry, can be used. These BRs can be used alone or in combination of two or more.

[0111] As the high-cis BR, for example, commercially available products from Zeon Corporation, UBE Industries, Ltd., JSR Corporation, etc. can be used. By containing high-cis BR, the low-temperature characteristics and wear resistance can be improved. The cis content of the high-cis BR is preferably greater than 95 mol%, more preferably greater than 96 mol%, still more preferably greater than 97 mol%. It should be noted that the cis content of BR is measured by the above-mentioned measurement method.

[0112] As the rare earth series BR, it is synthesized using a rare earth element series catalyst. The vinyl content is preferably less than 1.8 mol%, more preferably less than 1.6 mol%, and further preferably 1.5 mol% or less. The cis content is preferably greater than 95 mol%, more preferably greater than 96 mol%, and still more preferably 97 mol% or more. As the rare earth series BR, for example, commercially available products such as those of LANXESS Co., Ltd. can be used.

[0113] Examples of the BR containing SPB include: a BR containing SPB in which 1,2-syndiotactic polybutadiene crystals are dispersed after being chemically bonded to the BR, rather than simply dispersing the crystals in the BR. As such a BR containing SPB, commercially available products such as those of UBE Industries, Ltd. can be used.

[0114] As the modified BR, a modified butadiene rubber (modified BR) modified at the terminal and / or main chain with a functional group containing at least one element selected from silicon, nitrogen, and oxygen can also be appropriately used.

[0115] Examples of other modified BRs include: a substance obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound, and further having the terminal of the modified BR molecule bonded through a tin-carbon bond (tin-modified BR), etc. In addition, the modified BR can be either an unhydrogenated modified BR or a hydrogenated modified BR.

[0116] From the perspective of wear resistance, the weight average molecular weight (Mw) of the BR is preferably greater than 200,000, more preferably greater than 300,000, and further preferably greater than 400,000. In addition, from the perspective of crosslinking uniformity, etc., it is preferably less than 2,000,000, more preferably less than 1,000,000, and further preferably less than 800,000. It should be noted that Mw can be determined by the above method.

[0117] The content of BR in the rubber component is preferably 50% by mass or less, more preferably 40% by mass or less, further preferably 30% by mass or less, and particularly preferably 20% by mass or less. On the other hand, the lower limit value of this content is not particularly limited. For example, it can be 1% by mass or more, 3% by mass or more, 5% by mass or more, 7% by mass or more.

[0118] (Other rubber components) Within the range not affecting the effects of the present invention, the rubber component may contain other rubber components (non-diene rubbers) in addition to the diene rubber. As the non-diene rubber, rubber components commonly used in the tire industry can be used. For example, butyl rubber, ethylene-propylene rubber, polynorbornene rubber, silicone rubber, chlorinated polyethylene rubber, fluororubber (FKM), acrylic rubber (ACM), epichlorohydrin rubber, etc. can be cited. These other rubber components can be used alone or in combination of two or more. In addition, in addition to the above rubber components, a known thermoplastic elastomer may or may not be contained.

[0119] (Rubber components synthesized from recycled / biomass-derived raw materials) The monomers constituting synthetic rubbers such as SBR and BR can be derived from petroleum or recycled from rubber products such as tires or non-rubber products such as polystyrene. As the monomers obtained by recycling (recycled monomers), there is no particular limitation, and recycled butadiene, recycled aromatic vinyl compounds, etc. can be cited. As the butadiene, 1,2-butadiene and 1,3-butadiene can be cited. As the aromatic vinyl compound, there is no particular limitation, and styrene, etc. can be cited. Among them, recycled butadiene (recycled butadiene) and / or recycled styrene (recycled styrene) are preferably used as raw materials.

[0120] There is no particular limitation on the method for manufacturing the recycled monomer. For example, it can be cited as being synthesized from recycled naphtha obtained by decomposing rubber products such as tires. In addition, there is no particular limitation on the method for manufacturing the recycled naphtha. For example, rubber products such as tires can be decomposed under high temperature and high pressure, or rubber products such as tires can be decomposed in a microwave, or rubber products such as tires can be mechanically pulverized and then extracted.

[0121] In addition, monomers constituting polymers such as SBR and BR can be derived from biomass. The monomers derived from biomass (biomass monomers) are not particularly limited, and examples thereof include butadiene derived from biomass and aromatic vinyl compounds derived from biomass. As the butadiene, 1,2-butadiene and 1,3-butadiene can be mentioned. As the aromatic vinyl compound, there is no particular limitation, and styrene etc. can be mentioned. In addition, the method for producing biomass monomers is not particularly limited. For example, methods such as biological and / or chemical and / or physical conversion of animals and plants can be mentioned. As biological conversion, representative is fermentation by microorganisms. As chemical and / or physical conversion, conversion by a catalyst, conversion by high heat, conversion by high pressure, conversion by electromagnetic waves, conversion by a critical liquid, and combinations thereof can be mentioned. As biomass sources for these monomers, sugar or wood, plant residues after obtaining useful components, ethanol from plants, biomass naphtha, etc. can be mentioned.

[0122] As polymers synthesized from biomass monomer components (biomass polymers), there is no particular limitation, and examples thereof include polybutadiene rubber synthesized from butadiene derived from biomass and aromatic ethylene / butadiene copolymers synthesized from butadiene derived from biomass and / or aromatic vinyl compounds derived from biomass. As the aromatic ethylene / butadiene copolymer, for example, styrene-butadiene rubber synthesized from butadiene derived from biomass and / or styrene derived from biomass can be mentioned.

[0123] Whether the raw material of the polymer is derived from biomass can be judged by pMC (percent Modern Carbon) measured according to ASTM D6866-10. pMC refers to the 14 ratio of the 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 meaning of this value is as described below.

[0124] In 1 mole of carbon atoms (6.02×10 23 ), there are approximately one trillionth of the normal carbon atoms, that is, about 6.02×10 11 of 14 C. 14 The half-life of 14 C is 5730 years, and 14 14 C decreases regularly. Therefore, in fossil fuels such as coal, petroleum, and natural gas (which are considered to be produced after more than 226,000 years after carbon dioxide in the atmosphere etc. is taken up and fixed by plants), the 14All the C elements have decayed. Therefore, in the current 21st century, fossil fuels such as coal, oil, and natural gas contain no 14 C elements at all. Therefore, the chemical substances produced from these fossil fuels also contain no 14 C elements.

[0125] On the other hand, through nuclear reactions in the atmosphere by cosmic rays, 14 C is continuously generated. Therefore, due to radioactive decay, the 14 C reduction is balanced with the 14 C generation caused by nuclear reactions. In the Earth's atmospheric environment, the 14 C amount is a constant. Therefore, the 14 C concentration of substances from biomass resources that undergo material cycling in the current environment is about 1×10 -12 mol% relative to all carbon atoms as described above. Therefore, the difference in these values can be used to calculate the ratio (biomass ratio) of the compound (from biomass resources) from natural resources in a certain compound (rubber).

[0126] This 14 C is usually measured as follows. Using accelerator mass spectrometry based on a tandem [type] accelerator, the 13 C concentration ( 13 C / 12 C), 14 C concentration ( 14 C / 12 C) are measured. During the measurement, as the modern standard reference for the concentration of 14 C, the 14 C concentration in the circulating carbon in nature in 1950 is adopted. As a specific standard substance, the oxalic acid standard provided by NIST (National Institute of Standards and Technology) is used. The specific radioactivity of carbon in this oxalic acid (the radioactivity intensity of 14 C per 1 g of carbon) is distinguished for each carbon isotope. For 13 C, it is corrected to a certain value, and the value after 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.

[0127] Therefore, if rubber is made from materials derived from 100% biomass, although there are regional differences, etc., it shows a value of about 110 pMC (currently, in the normal state, most cases do not reach 100). On the other hand, for chemical substances from fossil fuels such as petroleum, when measuring the 14 C concentration, it shows a value of about 0 pMC (for example, 0.3 pMC). This value corresponds to the above-mentioned biomass ratio of 0%.

[0128] In summary, it is preferable to use materials such as rubber with a high pMC value (that is, materials such as rubber with a high biomass ratio) in the rubber composition in terms of environmental protection.

[0129] <Filler> In the rubber composition of this embodiment, as the filler, it is preferable to contain silica, and more preferably to contain silica and carbon black. In addition, the filler may be composed only of silica and carbon black.

[0130] (Silica) There is no particular limitation on the silica. For example, silica (anhydrous silica) prepared by the dry method, silica (hydrous silica) prepared by the wet method, etc., which are conventional products in the tire industry, can be used. There is no particular limitation on the raw material of the silica. For example, it may be a raw material from minerals such as quartz, or it may be a raw material from organisms such as rice husks (for example, silica using biomass materials such as rice husks as raw materials), or silica regenerated from products containing silica may be used. Among them, due to the reason of having more silanol groups, hydrous silica prepared by the wet method is preferred. These silicas can be used alone or in combination of two or more.

[0131] Silica using biomass materials as raw materials can be obtained, for example, by the following method: extracting silicate from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and using this silicate to react with sulfuric acid in the same way as conventional wet silica to form a precipitate of silica, and filtering, washing, drying, and pulverizing the obtained precipitate of silica.

[0132] Silica regenerated from products containing silica can be, for example, silica recovered from products containing silica such as semiconductor and other electronic components, tires, desiccants, diatomaceous earth and other filter materials. In addition, there is no particular limitation on the recovery method, and thermal decomposition, decomposition by electromagnetic waves, etc. can be cited. Among them, silica recovered from semiconductor and other electronic components or tires is preferred.

[0133] When silica crystallizes, it is insoluble in water, and the silicic acid of its components cannot be utilized. By controlling the combustion temperature and combustion time, the crystallization of silica in rice husk ash can be suppressed (see: JP-A No. 2009-2594; Akita Prefectural University Online Journal B / 2019, Vol. 6, pp. 216-222, etc.). Amorphous silica extracted from rice husks can use commercially available products such as those of Wilmar Corporation.

[0134] From the perspective of ensuring reinforcement and grip performance, the nitrogen adsorption specific surface area (N2SA) of silica is preferably 100 m 2 / g or more, more preferably 120 m 2 / g or more, further preferably 140 m 2 / g or more, further preferably 160 m 2 / g or more, particularly preferably 170 m 2 / g or more. In addition, from the perspective of heat generation and processability, it is preferably 350 m 2 / g or less, more preferably 300 m 2 / g or less, further preferably 250 m 2 / g or less. It should be noted that the N2SA of silica is measured by the above-mentioned measurement method.

[0135] The average primary particle size of silica is preferably 24 nm or less, more preferably 22 nm or less, further preferably 20 nm or less, particularly preferably 18 nm or less. The lower limit value of this average primary particle size is not particularly limited, but from the perspective of the dispersibility of silica, it is preferably 1 nm or more, more preferably 3 nm or more, further preferably 5 nm or more. It should be noted that the average primary particle size of silica is measured by the above-mentioned measurement method.

[0136] From the perspective of the effects of the present invention, when silica is contained, the content of silica is preferably 50 parts by mass or more, more preferably 60 parts by mass or more, further preferably 70 parts by mass or more, particularly preferably 80 parts by mass or more, relative to 100 parts by mass of the rubber component. In addition, this content is preferably 130 parts by mass or less, more preferably 120 parts by mass or less, further preferably 110 parts by mass or less.

[0137] (Silane coupling agent) Preferably, silica is used in combination with a silane coupling agent. The silane coupling agent is not particularly limited. For example, sulfur-containing silane coupling agents such as bis(3-triethoxysilylpropyl) disulfide and bis(3-triethoxysilylpropyl) tetrasulfide can be mentioned; 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; chlorine-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane, etc. Among them, sulfur-containing silane coupling agents and / or mercapto-based silane coupling agents are preferably contained. As the silane coupling agent, for example, commercially available products from Evonik Degussa, Momentive, etc. can be used. These silane coupling agents can be used alone or in combination of two or more.

[0138] (Carbon black) The carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N762, etc. The raw material of the carbon black can be biomass materials such as lignin and vegetable oil, or can be pyrolysis oil obtained by thermally decomposing waste tires. In addition, the carbon black can be manufactured by combustion such as the furnace method, or can be carried out by hydrothermal carbonization (HTC), or can be carried out by thermal decomposition of methane based on the thermal black method, etc. As commercially available products, products from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., Columbia Carbon, etc. can be used. These carbon blacks can be used alone or in combination of two or more.

[0139] In addition, as the carbon black, in addition to the above, from the perspective of life cycle assessment, etc., recycled carbon black obtained by thermally decomposing and refining carbon black made from biomass materials such as lignin and products containing carbon black such as tires can be used.

[0140] In this specification, "recycled carbon black" refers to carbon black obtained by pulverizing used articles such as tires containing carbon black and burning the pulverized material. It refers to carbon black in which, according to the thermogravimetric determination method of JIS K 6226-2:2003, when it is oxidized and burned by heating in air, the proportion of the mass (ash content) of ash as the non-combustible component is 13% by mass or more. That is, the proportion of the mass (carbon content) of the reduced component generated by the oxidation combustion of recycled carbon black is 87% by mass or less. Recycled carbon black is sometimes also represented by rCB.

[0141] Recycled carbon black can be obtained by the thermal decomposition process of used pneumatic tires. For example, "Rubber Chemistry and Technology", Vol. 85, No. 3, pp. 408-449 (2012) is mentioned in European Patent Application Publication No. 3427975, and particularly on pages 438, 440, and 442, it is recorded that it is obtained by thermally decomposing organic materials at 550-800 °C after removing oxygen or by vacuum thermal decomposition at a relatively low temperature (paragraph

[0027] ). As mentioned in paragraph

[0004] of JP Patent No. 6856781, the carbon black obtained by such a thermal decomposition process usually lacks functional groups on its surface (Comparison of the surface morphology and chemistry of thermally decomposed carbon black and commercially available carbon black, Powder Technology 160 (2005) 190-193).

[0142] Recycled carbon black may lack functional groups on its surface or may be treated to contain functional groups on its surface. The treatment for making recycled carbon black contain functional groups on its surface can be carried out by conventional methods. For example, in European Patent Application Publication No. 3173251, carbon black obtained by a thermal decomposition process is treated with potassium permanganate under acidic conditions to obtain carbon black containing hydroxyl groups and / or carboxyl groups on its surface. In addition, in JP Patent No. 6856781, carbon black obtained by a thermal decomposition process is treated with an amino acid compound containing at least one mercapto group or disulfide group to obtain carbon black with its surface activated. The recycled carbon black of this embodiment also includes carbon black that has been treated to contain functional groups on its surface.

[0143] Commercially available products from companies such as Strable Green Carbon and LDCarbon can be used as recycled carbon black.

[0144] From the perspective of reinforcing properties, the nitrogen adsorption specific surface area (N2SA) of carbon black is preferably 30 m 2 / g or more, more preferably 50 m 2 / g or more, further preferably 70 m 2 / g or more, and particularly preferably 90 m 2 / g or more. In addition, from the perspectives of low burnup performance and processability, the nitrogen adsorption specific surface area is preferably 200 m 2 / g or less, more preferably 150 m 2 / g or less, and further preferably 120 m 2 / g or less.

[0145] The average primary particle diameter of the carbon black is preferably 36 nm or less, more preferably 32 nm or less, further preferably 28 nm or less, and particularly preferably 24 nm or less. The lower limit of the average primary particle diameter is not particularly limited, and is preferably 5 nm or more, more preferably 8 nm or more, and further preferably 10 nm or more. It should be noted that the average primary particle diameter of the carbon black is measured by the above-mentioned measurement method.

[0146] From the perspective of reinforcement, when carbon black is contained, the content of carbon black is preferably 1 part by mass or more, more preferably 3 parts by mass or more, further preferably 5 parts by mass or more, and particularly preferably 7 parts by mass or more with respect to 100 parts by mass of the rubber component. In addition, from the perspective of suppressing heat generation, the content is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, further preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less.

[0147] (Other fillers) The filler may contain other fillers in addition to silica and carbon black. There is no particular limitation on other fillers. For example, fillers commonly used in the tire industry in the past, such as aluminum hydroxide, calcium carbonate, alumina, clay, and talc, can be compounded.

[0148] <Copolymer resin> The rubber composition of the present embodiment contains a copolymer resin (hereinafter, simply referred to as "copolymer resin") containing styrene and cyclopentadiene as monomer components.

[0149] As the copolymer resin, any resin containing styrene and cyclopentadiene as monomer components may be used, and there is no particular limitation. Other monomer components may be further contained. In addition, it may be a substance obtained by hydrogenating them or a substance obtained by modifying them.

[0150] The "styrene" as a monomer component may be a compound having a styrene structure other than styrene. For example, styrene, α-methylstyrene, vinyltoluene, chlorostyrene, etc. may be cited. Styrene monomers such as vinyltoluene (methylstyrene) are contained in, for example, C9 fractions. As other monomer components, there is no particular limitation, and monomer components commonly used in petroleum resins are preferred. For example, C9 fractions other than monomers having a styrene structure may be cited. As the C9 fraction other than monomers having a styrene structure, for example, at least one selected from benzofuran, indene, methylindene, etc. may be cited.

[0151] As the copolymer resin, a DCPD-C9 resin which is a copolymer of cyclopentadiene and / or dicyclopentadiene and a C9 fraction is preferred. In addition, it may be a substance obtained by hydrogenating the DCPD-C9 resin, or a substance obtained by modifying the DCPD-C9 resin.

[0152] As the copolymer resin containing styrene and cyclopentadiene as monomer components, for example, commercially available products of Exxon Mobil Corporation, ENEOS Corporation, Zeon Corporation, Maruzen Petrochemical Co., Ltd., etc. may be used. The copolymer resin may be used alone in one kind, or two or more kinds may be used in combination.

[0153] 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, further preferably 1.1% by mass or more, and particularly preferably 1.4% by mass or more. In addition, the upper limit value of the content of the styrene part is not particularly limited. For example, it may be set to less than 50% by mass, less than 40% by mass, less than 30% by mass, less than 20% by mass, less than 10% by mass, less than 5.0% by mass, less than 3.0% by mass.

[0154] From the viewpoint of the effects of the present invention, the softening point of the copolymer resin is preferably greater than 70 °C, more preferably greater than 80 °C, further preferably greater than 90 °C, and particularly preferably greater than 100 °C. In addition, from the viewpoint of improving processability and the dispersibility of the rubber component and the filler, the softening point is preferably less than 150 °C, more preferably less than 140 °C, and further preferably less than 130 °C. It should be noted that the softening point of the copolymer resin is measured by the above-mentioned measurement method.

[0155] The content of the copolymer resin (when there are two or more kinds, it is the total content) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, still more preferably 15 parts by mass or more, and particularly preferably 20 parts by mass or more, relative to 100 parts by mass of the rubber component. In addition, from the perspective of suppressing heat generation, the content is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, still more preferably 45 parts by mass or less, and particularly preferably 40 parts by mass or less.

[0156] <Other compounding agents> In the rubber composition of the present embodiment, in addition to the above components, compounding agents commonly used in the tire industry in the past can be appropriately contained, for example, plasticizers, vulcanized rubber particles, processing aids, waxes, anti-aging agents, stearic acid, zinc oxide, vulcanizing agents, vulcanization accelerators, etc.

[0157] In this specification, "plasticizer" refers to a material that imparts plasticity to the rubber component, and is a concept including both plasticizers that are liquid (liquid state) at normal temperature (25°C) and plasticizers that are solid at normal temperature (25°C). Examples of plasticizers can include resins, oils, liquid rubbers, ester-based plasticizers, etc. These plasticizers can be derived from petroleum, or can be derived from biomass, or can be derived from naphtha regenerated from rubber products or non-rubber products. In addition, low-molecular-weight hydrocarbon components obtained by thermal decomposition and extraction of used tires or products containing various components can be used as plasticizers. These plasticizers can be used alone or in combination of two or more.

[0158] (Resin) The rubber composition of the present embodiment may contain other resins in addition to the copolymer resin. There is no particular limitation on other resins, and resins commonly used in the tire industry can be used. For example, aromatic vinyl-based resins, dicyclopentadiene-based resins, C9-based resins, C5-based resins, C5C9-based resins, terpene-based resins, rosin-based resins, phenolic resins, etc. can be cited. Other resins can be used alone or in combination of two or more.

[0159] 《Aromatic vinyl-based resin》 In this specification, the "aromatic vinyl-based resin" refers to a resin containing at least one aromatic vinyl compound selected from styrene, α-methylstyrene, vinyltoluene, chlorostyrene, etc. as a monomer component. As the aromatic vinyl-based resin, due to reasons such as economy, easy processing, and excellent heat generation properties, a homopolymer of α-methylstyrene or styrene, or a copolymer of α-methylstyrene and styrene is preferred, and a copolymer of α-methylstyrene and styrene is more preferred. As the aromatic vinyl-based resin, for example, commercially available products from KARTON, Eastman Chemical Company, Mitsui Chemicals, Inc., etc. can be used. This resin can be used alone as one kind, or two or more kinds can be used in combination.

[0160] <<Dicyclopentadiene-based 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, commercially available products from ExxonMobil, ENEOS Corporation, Zeon Corporation, Maruzen Petrochemical Co., Ltd., etc. can be used. This resin can be used alone as one kind, or two or more kinds can be used in combination.

[0161] <<C9-based resin>> In this specification, the "C9-based resin" refers to a resin obtained by polymerizing C9 fractions, which can be a substance obtained by polymerizing C9 fractions alone, or a copolymer obtained by copolymerizing C9 fractions with other components. As the C9 fractions, for example, at least one petroleum fraction having 8 to 10 carbon atoms selected from alkylstyrenes such as vinyltoluene, benzofuran, indene, methylindene, etc. can be cited. As specific examples of the C9-based resin, for example, benzofuran-indene resin, benzofuran resin, indene resin, etc. can be cited. This resin can be used alone as one kind, or two or more kinds can be used in combination.

[0162] <<C5-based resin>> In this specification, the "C5-based resin" refers to a resin obtained by polymerizing C5 fractions other than cyclopentadiene, which can be a substance obtained by hydrogenating them or a substance obtained by modifying them. As the C5 fractions other than cyclopentadiene, for example, at least one petroleum fraction having 4 to 5 carbon atoms selected from isoprene, pentane, isopentane, neopentane, pentene, pentadiene, etc. can be cited. This resin can be used alone as one kind, or two or more kinds can be used in combination.

[0163] <<C5C9-based resin>> "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be a substance obtained by hydrogenating them or a substance obtained by modifying them. As the C5C9 petroleum resin, for example, commercially available products from Tosoh Corporation, LUHUA Company, etc. can be used. This resin can be used alone or in combination of two or more.

[0164] <<Terpene resin>> Terpene resin refers to a resin containing at least one terpene compound selected from α-pinene, β-pinene, limonene, dipentene, etc. as the monomer component with the highest content (preferably containing 50 mol% or more), and may be a substance obtained by hydrogenating them or a substance obtained by modifying them. As specific examples of terpene resin, for example, polyterpene resin containing only one or more of the above terpene compounds as monomer components; aromatic modified terpene resin containing the terpene compound and an aromatic compound as monomer components; terpene phenol resin containing the terpene compound and a phenolic compound as monomer components, etc. As the aromatic compound that is the monomer component of the aromatic modified terpene resin, for example, at least one selected from styrene, α-methylstyrene, vinyltoluene, divinyltoluene, etc. can be cited. As the phenolic compound that is the monomer component of the terpene phenol resin, for example, at least one selected from phenol, bisphenol A, cresol, xylenol, etc. can be cited. This resin can be used alone or in combination of two or more.

[0165] <<Rosin resin>> As rosin resin, it refers to a resin containing at least one rosin acid compound selected from abietic acid, neoabietic acid, palustric acid, isopimaric acid, etc., and may be a substance obtained by hydrogenating them or a substance obtained by modifying them. As rosin resin, there is no particular limitation. For example, natural resin rosin, rosin modified resin obtained by modifying it through hydrogenation, disproportionation, dimerization, esterification, etc. can be cited. This resin can be used alone or in combination of two or more.

[0166] <<Phenolic resin>> As phenolic resin, it refers to a resin containing phenolic compounds such as phenol and cresol as the monomer component with the highest content (preferably containing 50 mol% or more). As phenolic resin, there is no particular limitation, and phenolic resin, alkylphenolic resin, alkylphenol acetylene resin, oil-modified phenolic resin, etc. can be cited. This resin can be used alone or in combination of two or more.

[0167] From the perspective of the effects of the present invention, the total content of the resin (including the copolymer resin) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, further preferably 15 parts by mass or more, and particularly preferably 20 parts by mass or more, based on 100 parts by mass of the rubber component. Additionally, from the perspective of suppressing heat generation, the total content is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, further preferably 55 parts by mass or less, and particularly preferably 50 parts by mass or less.

[0168] From the perspective of suppressing heat generation, the content of the resin other than the copolymer resin (when two or more kinds are contained, it is the total content) is preferably less than 30 parts by mass, more preferably less than 20 parts by mass, further preferably less than 10 parts by mass, particularly preferably less than 5 parts by mass, or may not be contained, based on 100 parts by mass of the rubber component.

[0169] (Oil) As the oil, for example, mineral oil, vegetable oil, animal oil, etc. can be cited. As the mineral oil, paraffinic mineral oil (mineral oil), naphthenic mineral oil, aromatic mineral oil, etc. can be cited. Specific examples of the mineral oil, for example, can include: Mild Extract Solvate (MES), Distillate Aromatic Extract (DAE), Treated Distillate Aromatic Extract (TDAE), Treated Residual Aromatic Extract (TRAE), Residual Aromatic Extract (RAE), etc. Additionally, for environmental countermeasures, mineral oil with a low content of polycyclic aromatic compound (PCA) can also be used. As the mineral oil with a low PCA content, MES, TDAE, heavy naphthenic oil, etc. can be cited. Additionally, from the perspective of life cycle assessment, oil obtained by refining waste oil used in rubber mixers and engines and waste cooking oil used in restaurants can be used. The oil can be used alone in one kind, or two or more kinds can be used in combination.

[0170] As vegetable oils, for example, linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice bran oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grape seed oil, candelilla wax, etc. can be cited. In addition, as vegetable oils, the following can also be cited: 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, oxidative polymerized oils obtained by oxidizing the above oils, waste edible oils recovered from oils used as edible oils, etc. It should be noted that vegetable oils can be liquid or solid at normal temperature (25°C).

[0171] The vegetable oil preferably contains acylglycerol, and more preferably contains triacylglycerol. It should be noted that in this specification, acylglycerol refers to a compound in which the hydroxyl group of glycerol forms an ester bond with a fatty acid. As acylglycerol, there is no particular limitation, and it can be 1-monoacylglycerol, or it can be 2-monoacylglycerol, or it can be 1,2-diacylglycerol, or it can be 1,3-diacylglycerol, or it can be triacylglycerol. In addition, acylglycerol can be a monomer, or it can be a dimer, or it can be a multimer of trimer or higher. It should be noted that acylglycerols of dimer or higher can be obtained by thermal polymerization, oxidative polymerization, etc. In addition, acylglycerol can be liquid or solid at normal temperature (25°C).

[0172] As a method for confirming whether the acylglycerol is contained in the rubber composition, there is no particular limitation, and it can be confirmed by 1 1H-NMR measurement. For example, the rubber composition compounded with triacylglycerol is immersed in chloroform at normal temperature (25°C) for 24 hours, the rubber composition is removed, and then 1H-NMR is measured 1 at room temperature. 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 this signal is presumed to be the signal from the hydrogen atom bonded to the carbon atom (this carbon atom is adjacent to the oxygen atom of the ester group). It should be noted that the "around" in this paragraph refers to the range of ±0.10 ppm.

[0173] As the fatty acid, there is no particular limitation, and it can be an unsaturated fatty acid or a saturated fatty acid. As unsaturated fatty acids, monovalent unsaturated fatty acids such as oleic acid, and polyvalent unsaturated fatty acids such as linoleic acid and linolenic acid can be cited. In addition, as saturated fatty acids, butyric acid (butyric acid), lauric acid, etc. can be cited.

[0174] Among them, as the fatty acid, it is preferable to contain a fatty acid with fewer double bonds (i.e., saturated fatty acid or 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 can be used, or a modified vegetable oil such as transesterified oil can be used. In addition, in order to produce a vegetable oil containing such a fatty acid, plants can be improved through variety improvement, genetic recombination, genome editing, etc.

[0175] As the vegetable oil, for example, commercially available products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Olisoy, H&R, Toyokuni Oil Co., Ltd., Fuji Kogyo Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0176] As the animal oil, fish oil, beef tallow, whale oil, or oil alcohol derived from them can be mentioned.

[0177] From the perspective of processability, when oil is contained, relative to 100 parts by mass of the rubber component, the content of the oil is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, further preferably 15 parts by mass or more, and particularly preferably 20 parts by mass or more. In addition, from the perspective of wear resistance, the content is preferably 80 parts by mass or less, more preferably 70 parts by mass or less, further preferably 60 parts by mass or less, and particularly preferably 50 parts by mass or less. It should be noted that the content of the oil also includes the amount of oil contained in the oil-extended rubber.

[0178] (Liquid rubber) The liquid rubber can be any polymer that is in a liquid state at normal temperature (25 °C) and is not particularly limited. For example, 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. can be mentioned. The liquid rubber can be used alone or in combination of two or more.

[0179] When liquid rubber is contained, relative to 100 parts by mass of the rubber component, the content of the liquid rubber is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and further preferably 5 parts by mass or more. In addition, the content of the liquid rubber is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and further preferably 10 parts by mass or less. The content of the liquid rubber also includes the amount of the extender liquid rubber used in the increment of the rubber component.

[0180] (Ester plasticizer) As ester plasticizers, for example, dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), di-2-ethylhexyl azelate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), dilauryl 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. can be cited. The ester plasticizer can be used alone in one kind, or two or more kinds can be used in combination.

[0181] When containing an ester plasticizer, relative to 100 parts by mass of the rubber component, the content of the ester plasticizer is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and further preferably 5 parts by mass or more. In addition, the content of the ester plasticizer is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and further preferably 10 parts by mass or less. The content of the ester plasticizer also includes the amount of the extender ester plasticizer used in the increment of the rubber component.

[0182] From the perspective of the effects of the present invention, relative to 100 parts by mass of the rubber component, the total content of the plasticizer is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, further preferably 30 parts by mass or more, and particularly preferably 40 parts by mass or more. In addition, from the perspective of suppressing heat generation, the total content is preferably 90 parts by mass or less, more preferably 80 parts by mass or less, further preferably 70 parts by mass or less, and particularly preferably 60 parts by mass or less.

[0183] (Vulcanized rubber particles) Vulcanized rubber particles are particles made of vulcanized rubber. Specifically, rubber powder specified in JIS K 6316:2017, etc. can be used. From the perspectives of considering the environment and cost, recycled rubber powder made from crushed waste tires, etc. is preferred. Vulcanized rubber particles can be used alone in one kind, or two or more kinds can be used in combination.

[0184] As vulcanized rubber particles, there is no particular limitation, and they can be unmodified vulcanized rubber particles or modified vulcanized rubber particles. As commercially available products of vulcanized rubber, for example, products of Lehigh Company, Murakami Rubber Industry Co., Ltd., etc. can be used.

[0185] When containing vulcanized rubber particles, relative to 100 parts by mass of the rubber component, the content of the vulcanized rubber particles can be appropriately adjusted, for example, within the range of greater than 1 part by mass and less than 80 parts by mass.

[0186] (Processing aid) As a processing aid, for example, 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. can be cited. As a processing aid, for example, commercially available products from companies such as Schill+Seilacher and Performance Additive can be used. The processing aid can be used alone in one kind, or two or more kinds can be used in combination.

[0187] From the perspective of exerting the improvement effect of processability, when the processing aid is contained, relative to 100 parts by mass of the rubber component, the content of the processing aid is preferably 0.5 part by mass or more, more preferably 1.0 part by mass or more. In addition, from the perspective of wear resistance and breaking strength, the content is preferably 10 parts by mass or less, more preferably 8.0 parts by mass or less, and further preferably 5.0 parts by mass or less.

[0188] (Wax) As the wax, there is no particular limitation, and any of the waxes commonly used in the tire industry can be appropriately used. For example, petroleum waxes, mineral waxes, synthetic waxes, waxes from plants, etc. can be cited. Among them, petroleum waxes and waxes from plants are preferred, and petroleum waxes are more preferred. As the wax from plants, for example, rice wax, carnauba wax, candelilla wax, etc. can be cited. As the petroleum wax, for example, paraffin wax, microcrystalline wax, their selected special waxes, etc. can be cited, and paraffin wax is preferred. It should be noted that the wax of this embodiment does not contain stearic acid. Regarding the wax, for example, commercially available products from companies such as Ouchi Shinsei Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Paramelt can be used. The wax can be used alone in one kind, or two or more kinds can be used in combination.

[0189] From the perspective of the weather resistance of the rubber, when the wax is contained, relative to 100 parts by mass of the rubber component, the content of the wax is preferably 0.5 part by mass or more, more preferably 1.0 part by mass or more, and further preferably 1.5 part by mass or more. In addition, from the perspective of preventing the whitening of the tire caused by blooming, the content is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less.

[0190] (Antioxidant) As the anti-aging agent, there is no particular limitation, and examples thereof include: naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine, 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'-dimethylxyl-p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), 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-tert-butyl-4-methylphenol, styrenated phenol; bisphenol, triphenol, polyphenol-based anti-aging agents such as tetrakis[methylene-3-(3',5'-di-tert-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 commercially available products, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industrial Co., Ltd., Flexsys Company, etc. can be used. The anti-aging agent can be used alone in one kind, or two or more kinds can be used in combination.

[0191] From the perspective of ozone crack resistance of the rubber, when the anti-aging agent is contained, the content of the anti-aging agent is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and further preferably 1.5 parts by mass or more, based on 100 parts by mass of the rubber component. In addition, from the perspectives of wear resistance and wet grip performance, the content is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less.

[0192] (Stearic acid) From the perspective of processability, when stearic acid is contained, the content of stearic acid is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and further preferably 1.5 parts by mass or more, based on 100 parts by mass of the rubber component. In addition, from the perspective of vulcanization rate, the content is preferably 10 parts by mass or less, more preferably 5.0 parts by mass or less.

[0193] (Zinc oxide) From the perspective of processability, when zinc oxide is contained, the content of zinc oxide is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and further preferably 1.5 parts by mass or more, based on 100 parts by mass of the rubber component. In addition, from the perspective of wear resistance, the content is preferably 5.0 parts by mass or less, more preferably 4.5 parts by mass or less, and further preferably 4.0 parts by mass or less.

[0194] (Vulcanizing agent) As the vulcanizing agent, sulfur is preferably used. As sulfur, powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, etc. can be used. One kind of vulcanizing agent can be used alone, or two or more kinds can be used in combination.

[0195] From the perspective of ensuring sufficient vulcanization reaction, when sulfur is contained as the vulcanizing agent, the content of sulfur is preferably 0.1 part by mass or more, more preferably 0.3 part by mass or more, and still more preferably 0.5 part by mass or more with respect to 100 parts by mass of the rubber component. On the other hand, from the perspective of preventing deterioration, the content is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, and still more preferably 3.0 parts by mass or less. It should be noted that when sulfur containing oil is used as the vulcanizing agent, the content of the vulcanizing agent is the total content of the pure sulfur component contained in the sulfur containing oil.

[0196] As vulcanizing agents other than sulfur, for example, alkylphenol / sulfur chloride condensates, 1,6-hexamethylene-dithiocarbamate sodium dihydrate, 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane, etc. can be cited. Regarding these vulcanizing agents other than sulfur, commercially available products from companies such as Taoka Chemical Industry Co., Ltd., Lanxess AG, and Flexsys Inc. can be used. One kind of vulcanizing agent can be used alone, or two or more kinds can be used in combination.

[0197] (Vulcanization accelerator) As the vulcanization accelerator, for example, sulfenamide-based, thiazole-based, thiuram-based, thiourea-based, guanidine-based, dithiocarbamate-based, aldehyde-amine-based or aldehyde-ammonia-based, imidazoline-based or xanthate-based vulcanization accelerators, etc. can be cited. Among them, sulfenamide-based, thiazole-based, and guanidine-based vulcanization accelerators are preferred. One kind of vulcanization accelerator can be used alone, or two or more kinds can be used in combination.

[0198] As sulfenamide-based vulcanization accelerators, for example, N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N,N-dicyclohexyl-2-benzothiazolylsulfenamide (DCBS), etc. can be cited. Among them, N-cyclohexyl-2-benzothiazolylsulfenamide (CBS) is preferred.

[0199] As thiazole-based vulcanization accelerators, for example, 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, bis(2-benzothiazolyl) disulfide, etc. can be cited. Among them, 2-mercaptobenzothiazole is preferred.

[0200] As guanidine-based vulcanization accelerators, for example, the following can be cited: 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salt of di-catechol borate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylylguanidine, 1,3-di-o-cumenyl-2-propionylguanidine, etc. Among them, 1,3-diphenylguanidine (DPG) is preferred.

[0201] When a vulcanization accelerator is contained, relative to 100 parts by mass of the rubber component, the content of the vulcanization accelerator is preferably 1.0 part by mass or more, more preferably 1.5 part by mass or more, and still more preferably 2.0 part by mass or more. In addition, relative to 100 parts by mass of the rubber component, the content of the vulcanization accelerator is preferably 8.0 parts by mass or less, more preferably 7.0 parts by mass or less, and still more preferably 6.0 parts by mass or less. By setting the content of the vulcanization accelerator within the above range, there is a tendency to ensure the breaking strength and elongation at break.

[0202] <Various materials containing carbon atoms> In this specification, various materials containing carbon atoms (for example, rubber, oil, resin, vulcanization accelerator, anti-aging agent, surfactant, etc.) can be derived from carbon dioxide in the atmosphere. As a method for obtaining the various materials from carbon dioxide, carbon dioxide can be directly converted, or methane obtained through a methanation process of synthesizing methane from carbon dioxide can be converted.

[0203] [Manufacturing method] The rubber composition can be manufactured by a known method. For example, it can be manufactured by kneading the respective components using a rubber kneading device such as an open mill, a closed kneader (Banbury mixer, kneader, etc.).

[0204] The kneading process includes, for example, a basic 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 basic kneading process and kneading. In addition, the basic kneading process can also be divided into multiple processes as needed.

[0205] As the kneading conditions, there are no particular limitations. For example, the following methods can be cited: in the basic kneading process, kneading at a discharge temperature of 150 to 170 °C for 3 to 10 minutes, and in the final kneading process, kneading at 70 to 110 °C for 1 to 5 minutes.

[0206] The tire of the present embodiment can be manufactured by a conventional method using the rubber composition. That is, a tire can be manufactured by the following method: extruding the rubber composition in an unvulcanized state into the shape of a tread portion using an extruder with a die of a specified shape, and on a tire molding machine, while adjusting to a specified tire structure, bonding it together with other tire components, and forming it by a conventional method to form an unvulcanized tire, and then heating and pressurizing the unvulcanized tire in a vulcanizer. As the vulcanization conditions, there are no particular limitations. For example, a method of vulcanizing at 140 to 170 °C for 10 to 40 minutes can be cited.

[0207] [Use] In this specification, the tire can be used for any purpose, 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 load tire, a run-flat tire. It should be noted that a passenger car tire refers to a tire premised on being installed on a motor vehicle traveling on four wheels, and its maximum load capacity is less than 1400 kg. In addition, a heavy load tire refers to a tire whose maximum load capacity is 1400 kg or more. In addition, in this specification, in addition to being used for all-season tires and summer tires, the tire can also be used for winter tires such as studless tires. [Examples]

[0208] Hereinafter, examples (Examples) considered to be preferable in implementation are shown, but the scope of the present invention is not limited to the Examples.

[0209] Research was conducted on a tire having a tread portion (the tread portion was made using the following various chemicals and a rubber composition obtained by changing the formulation according to Table 1), and the results were calculated based on the following evaluation methods, and the results are shown in Table 1. NR: TSR20 SBR1: HPR830E manufactured by JSR Corporation (S-SBR, Tg: -23 °C, styrene content: 39.5 mass%, vinyl content: 38.5 mol%, containing 10.0 mass parts of a filler oil component relative to 100 mass parts of the rubber solid component) SBR2: SBR manufactured by the following Production Example 1 (S-SBR, Tg: -50 °C, styrene content: 30 mass%, vinyl content: 22 mol%, non-oil-filled) SBR3: SBR manufactured by the following Production Example 2 (S-SBR, Tg: -66 °C, styrene content: 19 mass%, vinyl content: 19 mol%, non-oil-filled) BR: UBEPOL BR (registered trademark) 150B manufactured by UBE Industries, Ltd. (unmodified BR, cis content: 97 mol%, Mw: 440,000) Carbon black: DIABLACK I (N220, N2SA: 114 m 2 / g, average primary particle size: 22 nm) manufactured by Mitsubishi Chemical Corporation Silica: ULTRASIL VN3 (N2SA: 175 m 2 / g, average primary particle size: 18 nm) manufactured by Evonik Degussa Silane coupling agent: Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa Oil: VivaTech 500 (TDAE oil) manufactured by H&R Co., Ltd. Copolymer resin: Oppera PR383 (hydrogenated DCPD-C9 resin containing styrene and cyclopentadiene as monomer components, Mw: 770, softening point: 103 °C, styrene content: 1.78 mass%) manufactured by ExxonMobil Terpene resin: YS Resin PX1150N (polyterpene resin, softening point: 115 ± 5 °C) manufactured by Yasuhara Chemical Co., Ltd. Antioxidant 1: NOCRAC 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. Antioxidant 2: NOCRAC RD (poly(2,2,4-trimethyl-1,2-dihydroquinoline)) manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. Stearic acid: Bead stearic acid "Tsubaki" manufactured by NOF Corporation Zinc oxide: Zinc white No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Sulfur: Powder sulfur manufactured by Karuizawa Sulfur Co., Ltd. Vulcanization accelerator 1: Nocceler CZ-G (N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS)) manufactured by Ouchi Shinko Chemical Industrial Co., Ltd. Vulcanization accelerator 2: Nocceler D (1,3-diphenylguanidine (DPG)) manufactured by Ouchi Shinko Chemical Industrial Co., Ltd.

[0210] (Production Example 1: Production of SBR2) In a nitrogen-purged autoclave reactor, cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene were added. The ratio of styrene to 1,3-butadiene was adjusted so that the styrene content was 30% by mass. After adjusting the temperature of the reactor contents to 20 °C, n-butyllithium was added to initiate polymerization. Polymerization was carried out under adiabatic conditions, and the maximum temperature reached 80 °C. After confirming the formation of a polymer with an Mw of 854,000 by GPC, the polymerization solution was poured into 4 L of ethanol to recover the precipitate. After subjecting the obtained precipitate to air drying, vacuum drying was carried out under conditions of 80 °C / 10 Pa or less until the drying loss reached 0.1% to obtain SBR2.

[0211] (Production Example 2: Production of SBR3) In a nitrogen-purged autoclave reactor, cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene were added. The ratio of styrene to 1,3-butadiene was adjusted so that the styrene content was 19% by mass. After adjusting the temperature of the reactor contents to 20 °C, n-butyllithium was added to initiate polymerization. Polymerization was carried out under adiabatic conditions, and the maximum temperature reached 80 °C. After confirming the formation of a polymer with an Mw of 679,000 by GPC, the polymerization solution was poured into 4 L of ethanol to recover the precipitate. After subjecting the obtained precipitate to air drying, vacuum drying was carried out under conditions of 80 °C / 10 Pa or less until the drying loss reached 0.1% to obtain SBR3.

[0212] (Examples and Comparative Examples) According to the formulation shown in Table 1, using a 1.7 L closed Banbury mixer, the chemicals other than sulfur and vulcanization accelerators were kneaded for 1 to 10 minutes until the discharge temperature reached 150 to 160 °C to obtain a kneaded product. Then, using a two-roll mill, sulfur and vulcanization accelerators were added to the obtained kneaded product and kneaded for 4 minutes until the temperature reached 105 °C to obtain an unvulcanized rubber composition. The obtained unvulcanized rubber composition was formed into the shape of a tread portion and bonded to other tire components such as a belt layer to produce an unvulcanized tire, which was press-cured at 150 °C for 35 minutes to obtain each test tire (195 / 65R15) described in Table 1. Here, the belt cord is a cord obtained by twisting two yarns each formed by twisting filaments made of polyester fiber (in Comparative Examples 2 and 3, nylon 6), and the distance G from the tread surface to the belt cord is 9.0 mm.

[0213] <Measurement of tanδ at 0 °C> From the tread surface of each test tire, specimens of vulcanized rubber were cut out in the form of a rectangle with a length of 20 mm, a width of 4 mm, and a thickness of 1 mm, with the circumferential direction of the tire as the long side and the radial direction of the tire as the thickness direction. For each specimen of vulcanized rubber, a dynamic viscoelasticity measuring device (EPLEXOR series manufactured by GABO) was used to measure the loss tangent tanδ under the conditions of a temperature of 0 °C, a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±2.5%, and a tensile mode.

[0214] <Measurement of E* at 30 °C> From the tread surface of each test tire, specimens of vulcanized rubber were cut out in the form of a rectangle with a length of 20 mm, a width of 4 mm, and a thickness of 1 mm, with the circumferential direction of the tire as the long side and the radial direction of the tire as the thickness direction. For each specimen of vulcanized rubber, a dynamic viscoelasticity measuring device (EPLEXOR series manufactured by GABO) was used to measure the complex elastic modulus E* under the conditions of a temperature of 30 °C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain of ±1%, and a tensile mode.

[0215] <Handling stability> Each test tire was mounted on the four wheels of an FF passenger car with a displacement of 2000 cc, and real vehicle driving was carried out on a test track on a dry asphalt road surface. The handling characteristics were evaluated based on various sensations during straight driving, lane change, acceleration, and deceleration when the test driver was driving at a speed of 100 km / h. The evaluation was carried out with integer values from 1 to 5 points. Based on the evaluation criterion that the higher the score, the better the handling characteristics, the total score of 20 test drivers was calculated. The total score of the tire in Comparative Example 1 was converted into a reference value (100), and the evaluation results of each test tire were expressed in an exponential form proportional to the total score.

[0216] <Wet grip performance> Each test tire was mounted on the four wheels of an FF sedan with a displacement of 2000 cc, and the braking distance from an initial speed of 100 km / h was measured on a wet asphalt road surface. The measurement results were expressed in an exponential form using the following formula. The larger the index, the shorter the braking distance and the better the wet grip performance. (Wet grip performance index) =(Braking distance of the tire in Comparative Example 3) / (Braking distance of each test tire)×100

[0217] <Comprehensive performance> The sum of the handling stability and wet grip performance indices was expressed as the comprehensive performance index.

[0218] [Table 1]

[0219] <Embodiment> Examples of embodiments of the present invention are shown below. [1] A tire having a tread surface and a belt layer existing radially inside the tread surface, wherein the belt layer has belt cords including filaments formed of polyester fibers, the tread surface is composed of a rubber composition, the rubber composition contains a rubber component including styrene-butadiene rubber and / or isoprene-based rubber and a copolymer resin including styrene and cyclopentadiene as monomer components, when the cord diameter of the belt cord is D (mm) and the total styrene amount in the rubber composition when the mass of the rubber component is 100% by mass is S (% by mass), D×S is greater than 0.05. [2] The tire according to [1] above, wherein the polyester fiber is recycled polyester fiber. [3] The tire according to [1] or [2] above, wherein D×S is greater than 1.0. [4] The tire according to [3] above, wherein D×S is greater than 1.0 and less than 30.0. [5] The tire according to any one of [1] to [4] above, wherein when the complex elastic modulus of the rubber composition at 30°C is 30°C E* (MPa), 30°C E*×D is 3.0 or more, preferably 3.5 or more and 7.0 or less. [6] The tire according to any one of [1] to [5] above, wherein the tanδ (0°C tanδ) of the rubber composition at 0°C is 0.45 or more, preferably 0.50 or more and 0.90 or less. [7] The tire according to any one of [1] to [6] above, wherein the rubber composition contains 60 parts by mass or more, preferably 70 parts by mass or more and 130 parts by mass or less of silica with respect to 100 parts by mass of the rubber component. [8] The tire according to any one of [1] to [7] above, wherein in the rubber composition, the content of the copolymer resin is 10 parts by mass or more, preferably 15 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the rubber component. [9] The tire according to any one of [1] to [8] above, wherein the distance G from the tread surface to the belt cord is 12.0 mm or less, preferably 5.0 mm or more and 10.0 mm or less.

Claims

1. A tire, characterized in that, it has a tread surface and a belt layer existing on the radially inner side of the tread surface, the belt layer has belt cords containing filaments formed of polyester fibers, the tread surface is composed of a rubber composition containing a rubber component including styrene-butadiene rubber and / or isoprene-based rubber and a copolymer resin containing styrene and cyclopentadiene as monomer components, when the cord diameter of the belt cord is D and the total styrene amount in the rubber composition when the mass of the rubber component is 100 mass% is S, D×S is greater than 0.05, wherein, the unit of D is mm and the unit of S is mass%.

2. The tire according to claim 1, wherein, The polyester fiber is recycled polyester fiber.

3. The tire according to claim 1, wherein, D×S is greater than 1.

0.

4. The tire according to claim 1, wherein, D×S is greater than 1.0 and less than 30.

0.

5. The tire according to any one of claims 1 to 4, wherein, when the complex elastic modulus of the rubber composition at 30°C is 30°C E*, 30°C E*×D is 3.0 or more, wherein, the unit of 30°C E* is MPa.

6. The tire according to any one of claims 1 to 4, wherein, The tanδ of the rubber composition at 0°C, i.e., 0°C tanδ, is 0.45 or more.

7. The tire according to any one of claims 1 to 4, wherein, Relative to 100 mass parts of the rubber component, the rubber composition contains 60 mass parts or more of silica.

8. The tire according to any one of claims 1 to 4, wherein, In the rubber composition, relative to 100 mass parts of the rubber component, the content of the copolymer resin is 10 mass parts or more.

9. The tire according to any one of claims 1 to 4, wherein, The distance G from the tread surface to the belt cord is 12.0 mm or less.

10. The tire according to claim 1, wherein, The cord diameter D of the belt cord is 0.40 mm or more and 0.90 mm or less, and the total styrene amount S in the rubber composition is 10 mass% or more and 34 mass% or less.

11. The tire according to claim 6, wherein, The tanδ of the rubber composition at 0°C, i.e., 0°C tanδ, is 0.45 or more and 1.00 or less.

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