tire

Abstract

To provide a tire which can improve total performance of low fuel consumption performance and ozone resistance.SOLUTION: A tire includes a side wall, wherein the side wall is composed of a rubber composition containing a rubber component, the rubber component contains isoprene-based rubber, and a branched conjugated diene copolymer, the branched conjugated diene copolymer has an ethylene unit, and a structural unit derived from a 1,3-diene compound represented by CH2=CR-CH=CH2 (wherein, R represents a hydrocarbon group having 3 or more carbon atoms), and when an ethylene unit content in the branched conjugated diene copolymer is represented by M (mol%), a thickness of a surface rubber layer at a tire maximum width position is represented by T (mm), and a content of the branched conjugated diene copolymer in the rubber component is represented by CSW (mass%), M is 50 or more, and M×CSW / T3 exceeds 70.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Rubber compositions for tires are required to have ozone resistance, i.e., to prevent cracking and deterioration of rubber due to atmospheric ozone. Because tire sidewalls are components that come into direct contact with the outside air and are visible to the public when mounted on a vehicle, rubber compositions for sidewalls are required to have superior ozone resistance to other tire components.

[0003] Furthermore, tires are being required to have even greater fuel efficiency.

[0004] Patent Document 1 describes that a rubber composition for a sidewall containing a rubber component and wax derived from sunflower seeds improves fuel economy and ozone resistance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-133844 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a tire that can improve the overall performance of fuel economy and ozone resistance. [Means for solving the problem]

[0007] The present invention provides a tire having a sidewall, the sidewall is made of a rubber composition containing a rubber component, the rubber component includes an isoprene-based rubber and a branched conjugated diene copolymer; The branched conjugated diene copolymer has a structural unit derived from an ethylene unit and a 1,3-diene compound represented by CH2=CR-CH=CH2 (wherein R represents a hydrocarbon group having 3 or more carbon atoms), The ethylene unit content in the branched conjugated diene copolymer is M (mol%), The thickness of the surface rubber layer at the maximum tire width position is T (mm). The content of the branched conjugated diene copolymer in the rubber component is C SW (mass%), M is 50 or more, M×C SW / T 3 Regarding tires, the number is over 70. [Effects of the Invention]

[0008] According to the present invention, a tire is provided that can improve the overall performance of fuel economy and ozone resistance. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic partial cross-sectional view of a tire according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] A tire according to one embodiment of the present invention is a tire having a sidewall, the sidewall being made of a rubber composition containing a rubber component, the rubber component including an isoprene-based rubber and a branched conjugated diene copolymer, the branched conjugated diene copolymer having an ethylene unit and a structural unit derived from a 1,3-diene compound represented by CH═CR-CH═CH (wherein R represents a hydrocarbon group having 3 or more carbon atoms), the ethylene unit content in the branched conjugated diene copolymer being M (mol %), the thickness of a surface rubber layer at a maximum width position of the tire being T (mm), and the content of the branched conjugated diene copolymer in the rubber component being C SW(mass%), M is 50 or more, and M × C SW / T 3 It is a tire with a value of over 70.

[0011] The reason why the tire of the present embodiment improves the overall performance of fuel economy and ozone resistance is thought to be, for example, as follows, without intending to be bound by theory.

[0012] First, (1) the rubber composition that makes up the sidewall contains an isoprene-based rubber in the rubber component, which improves dispersibility with the compounding ingredients contained in the rubber composition, which is thought to contribute to improved fuel economy. Also, (2) the inclusion of a specific branched conjugated diene copolymer in the rubber component improves compatibility of the rubber component, making it less likely for cracks to occur on the sidewall surface even after long periods of driving, which is thought to contribute to improved ozone resistance.

[0013] Furthermore, (3) since the ethylene unit content in the branched conjugated diene copolymer is 50 mol% or more, compatibility with other rubber components and co-crosslinkability with adjacent members of the sidewall are improved, which is thought to contribute to improving overall performance.

[0014] Furthermore, the ethylene unit content in the predetermined branched conjugated diene copolymer is defined as M (mol %), the thickness of the surface rubber layer at the maximum tire width position is defined as T (mm), and the content of the branched conjugated diene copolymer in the rubber component is defined as C SW (mass%), (4) M × C SW / T 3 When the ethylene unit content is more than 70, the sidewall becomes thinner relative to the ethylene unit content, and the strain on the sidewall during vehicle travel can be reduced, making the protective film less likely to crack. As a result, ozone cracks and fissures are less likely to occur.

[0015] It is believed that the cooperation of the above (1) to (4) will achieve a remarkable effect of providing a tire that improves the overall performance of fuel economy and ozone resistance.

[0016] The 1,3-diene compound is preferably farnesene and / or myrcene from the viewpoint of practical aspects such as easy availability of the monomer and because the effects of the present invention can be more suitably obtained.

[0017] The rubber component preferably further contains butadiene rubber.

[0018] It is believed that the inclusion of butadiene rubber improves the compatibility between the predetermined branched conjugated diene copolymer and other rubber components, further improving ozone resistance.

[0019] M×C SW / T 3 From the viewpoint of the effects of the present invention, it is preferable that the value is more than 300.

[0020] The T is preferably greater than 1.0 mm and less than 2.5 mm.

[0021] By setting the thickness T of the surface rubber layer at the tire's maximum width position within the above range, it is believed that the strain applied to the sidewall during vehicle travel is reduced, making ozone cracks and fissures less likely to occur, and further improving ozone resistance.

[0022] The rubber composition preferably contains carbon black.

[0023] The carbon black N2SA contained in the rubber composition is selected from the viewpoint of fuel economy performance, and is 100m 2 / g or more 140m 2 It is preferable that the carbon black content is not more than 1 / g.

[0024] From the viewpoint of fuel economy, the average primary particle diameter of the carbon black contained in the rubber composition is preferably 15 nm or more and 25 nm or less.

[0025] [Definition] The term "sidewall" refers to a component that includes a portion that forms the side surface of a tire, and is positioned radially inward of the tread portion and radially outward of the bead portion.

[0026] "Normal condition" refers to a condition in which the tire is mounted on a normal rim and filled with air at normal internal pressure, with no load applied.

[0027] "Genuine rim" refers to the rim specified for each tire in the standard system that includes the standard on which the tire is based. For example, for JATMA (Japan Automobile Tire Manufacturers Association), it refers to the standard rim for the applicable size listed in the "JATMA YEAR BOOK," for ETRTO (The European Tyre and Rim Technical Organization), it refers to the "Measuring Rim" listed in the "STANDARDS MANUAL," and for TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" listed in the "YEAR BOOK." JATMA, ETRTO, and TRA are referenced in that order, and if an applicable size is available at the time of reference, that standard is followed. In the case of a tire not specified in the above standards, it refers to the narrowest rim among the smallest diameter rims that can be mounted on the tire and can maintain internal pressure (i.e., no air leaks from between the rim and tire).

[0028] "Normal internal pressure" refers to the air pressure specified for each tire in the standard system that includes the standard on which the tire is based. For example, for JATMA, it is "maximum air pressure," for ETRTO, it is "INFLATION PRESSURE," and for TRA, it refers to the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES." As with regular rims, refer to JATMA, ETRTO, and TRA in that order, and follow that standard if there is an applicable size at the time of reference. In the case of tires not specified in the above standards, it refers to the normal internal pressure (250kPa or more) of another tire size (defined in the standard) that is specified using the regular rim as the standard rim, and if there are multiple normal internal pressures of 250kPa or more listed, it refers to the smallest value among them.

[0029] "Normal load" refers to the load specified for each tire in the standard system that includes the standard on which the tire is based. For example, for JATMA it is "Maximum Load Capacity", for ETRTO it is "Load Capacity", and for TRA it is the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". As with normal rims and normal internal pressures, JATMA, ETRTO, and TRA should be referenced in that order, and if there is an applicable size at the time of reference, that standard should be followed. For tires not specified in the above standards, the maximum load capacity W calculated separately should be used. L is the normal load.

[0030] "Maximum load capacity W L " is calculated using the following formula: "V" is the virtual volume of the tire (mm 3), "Dt" is the outer diameter (mm) of the tire in its normal state, "Ht" is the tire's cross-sectional height (mm) in the radial direction of the tire in a cross section of the tire taken along a plane including the tire's rotation axis, and "Wt" is the tire's cross-sectional width (mm) in its normal state. Ht can be calculated by (Dt-R) / 2, where R is the tire rim diameter. Wt is the value obtained by excluding any patterns or letters on the tire sidewall. Note that maximum load capacity is synonymous with the normal load mentioned above.

[0031]

number

[0032] "The thickness T of the surface rubber layer at the tire's maximum width position" is the distance (mm) from the sidewall surface to the carcass cord surface, measured along the normal line of the tire's maximum width position PW on the sidewall. "The tire's maximum width position PW" refers to the maximum width position in the tire's widthwise cross section measured under normal conditions. "The surface rubber layer" includes the sidewall.

[0033] The "glass transition temperature of the copolymer" is measured in accordance with JIS K 7121 using a differential scanning calorimeter (e.g., Q200 manufactured by TA Instruments Japan Co., Ltd.) while increasing the temperature at a rate of 10°C / min.

[0034] The "styrene content" is calculated by pyrolysis gas chromatography. In this specification, "pyrolysis gas chromatography" refers to a method in which a sample is heated in a pyrolysis apparatus, the individual components contained in the gas phase components generated by this heating are separated using a separation column, and each isolated component is analyzed. The "vinyl content (amount of 1,2-bonded butadiene units)" is also calculated by pyrolysis gas chromatography.

[0035] The "cis content (amount of cis-1,4-bonded butadiene units)" is a value calculated by pyrolysis gas chromatography in the same manner as the styrene content, and is applied to rubber components having repeating units derived from butadiene, such as SBR and BR.

[0036] The "weight average molecular weight (Mw)" can be determined by converting the measured value into a standard polystyrene equivalent value using gel permeation chromatography (GPC) (for example, a GPC-8000 series manufactured by Tosoh Corporation, a differential refractometer as the detector, and a TSKgel SuperMultipore HZ-M column manufactured by Tosoh Corporation). This applies to, for example, copolymers, butadiene rubbers, plasticizers, etc.

[0037] The "nitrogen adsorption specific surface area (N2SA) of carbon black" is measured in accordance with JIS K 6217-2:2017.

[0038] The "average primary particle size of carbon black" is a value determined by photographing particles with a transmission or scanning electron microscope and arithmetically averaging the particle sizes of 400 particles. If the particle shape is spherical, the particle size is the diameter of the sphere; if the particle shape is non-spherical, the particle size is calculated from the microscope image as the circle-equivalent diameter (positive square root of {4 × (particle area) / π}).

[0039] "Plasticizer" is a material that imparts plasticity to rubber components and is a component that is extracted from rubber compositions using acetone. Plasticizers include those that are liquid (fluid) at 25°C and those that are solid at 25°C. However, this does not include waxes and stearic acid, which are commonly used in the tire industry.

[0040] [tire] The tire according to the present embodiment is a tire having a sidewall made of a predetermined rubber composition, wherein the rubber component in the rubber composition contains an isoprene-based rubber and a predetermined branched conjugated diene copolymer, and the ethylene unit content of the branched conjugated diene copolymer is M (mol %), the thickness of the surface rubber layer at the maximum width position of the tire is T (mm), and the content of the branched conjugated diene copolymer in the rubber component is C SW (mass%), M is 50 or more, and M × C SW / T 3 is over 70.

[0041] <M×C SW / T 3 > In the tire according to this embodiment, M×C SW / T 3 is greater than 70, preferably greater than 100, more preferably greater than 200, even more preferably greater than 300, even more preferably greater than 350, still more preferably greater than 400, and particularly preferably greater than 500. SW / T 3 is preferably less than 1500, more preferably less than 1400, and even more preferably less than 1300. SW , and T will be described later.

[0042] A tire according to one embodiment of the present invention will be described below with reference to the drawings. Note that the embodiment described below is merely an example, and the tire of the present invention is not limited to the following embodiment.

[0043] Fig. 1 illustrates a tire according to one embodiment of the present invention. Fig. 1 shows a portion of a cross section perpendicular to the circumferential direction of the tire. In Fig. 1, the up-down direction is the tire radial direction, the left-right direction is the tire axial direction, and the direction perpendicular to the paper surface is the tire circumferential direction.

[0044] Although FIG. 1 shows only the portion to the right of the tire equator CL, a similar structure extends to the left of CL with CL as the axis of symmetry.

[0045] The tire in FIG. 1 includes a tread portion 1 extending in the circumferential direction to form an annular shape, sidewalls 31 arranged on both sides of the tread portion, bead portions having bead cores 21, at least one layer of carcass 33 anchored to the bead cores 21, and at least one layer of belt 2 arranged radially outward of the carcass 33. An inner liner 32 is present below the belt 2. The tire according to this embodiment is a tire having sidewalls, and preferably includes the components shown in FIG. 1 as other components. A band 3 may be present between the tread portion 1 and the belt 2, or the band 3 may not be present.

[0046] From the viewpoint of the effects of the present invention, the thickness T of the surface rubber layer at the tire maximum width position is preferably 1.0 mm or more, more preferably 1.3 mm or more, even more preferably 1.5 mm or more, and particularly preferably 1.7 mm or more. Also, from the viewpoint of the effects of the present invention, T is preferably 8.0 mm or less, more preferably 6.0 mm or less, even more preferably 4.0 mm or less, even more preferably 3.0 mm or less, and particularly preferably 2.4 mm or less.

[0047] [Rubber composition] The rubber composition constituting the sidewall of the tire according to the present embodiment (hereinafter referred to as the rubber composition according to the present embodiment) contains a rubber component containing an isoprene-based rubber and a predetermined branched conjugated diene copolymer. The rubber composition according to the present embodiment will be described below.

[0048] <Rubber component> The rubber composition according to the present embodiment contains, as rubber components, an isoprene-based rubber and a branched conjugated diene copolymer, and preferably further contains a butadiene rubber.

[0049] (Isoprene rubber) Examples of isoprene-based rubbers that can be used include those commonly used in the tire industry, such as isoprene rubber (IR) and natural rubber. Natural rubber includes unmodified natural rubber (NR) as well as modified natural rubbers such as epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), highly purified natural rubber, and grafted natural rubber. These isoprene-based rubbers may be used alone or in combination of two or more.

[0050] The NR is not particularly limited, and those commonly used in the tire industry can be used, such as SIR20, RSS#3, and TSR20.

[0051] The content of the isoprene-based rubber in the rubber component is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, and particularly preferably 35% by mass or more. From the viewpoint of blending other rubber components, the content of the isoprene-based rubber is preferably 80% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less.

[0052] (Branched conjugated diene copolymer) The branched conjugated diene copolymer contained in the rubber composition according to this embodiment has structural units derived from an ethylene unit and a 1,3-diene compound represented by CH═CR-CH═CH (wherein R represents a hydrocarbon group having 3 or more carbon atoms). The branched conjugated diene copolymer is not particularly limited in the arrangement of each unit, and may be a random copolymer obtained by random copolymerization or a block copolymer obtained by block copolymerization, but is preferably a random copolymer.

[0053] The ethylene unit is a structural unit derived from ethylene in the branched diene copolymer. The ethylene unit may be formed by hydrogenation of a structural unit derived from 1,3-butadiene (butadiene unit).

[0054] From the viewpoint of the effects of the present invention, the ethylene unit content M of the branched conjugated diene copolymer is 50 mol% or more, preferably 55 mol% or more, more preferably 60 mol% or more, and even more preferably 65 mol% or more. Also, the ethylene unit content M of the branched conjugated diene copolymer is preferably 90 mol% or less, more preferably 85 mol% or less, and even more preferably 80 mol% or less.

[0055] The 1,3-diene compound contained in the branched conjugated diene copolymer contained in the rubber composition according to this embodiment is a 1,3-diene compound represented by the following formula. CH2=CR-CH=CH2 (In the formula, R represents a hydrocarbon group having 3 or more carbon atoms.)

[0056] R is a hydrocarbon group having 3 or more carbon atoms, preferably a hydrocarbon group having 3 to 50 carbon atoms, more preferably a hydrocarbon group having 3 to 40 carbon atoms, even more preferably a hydrocarbon group having 3 to 30 carbon atoms, still more preferably a hydrocarbon group having 3 to 20 carbon atoms, still more preferably a hydrocarbon group having 3 to 15 carbon atoms, and particularly preferably a hydrocarbon group having 5 to 12 carbon atoms.

[0057] The hydrocarbon is not particularly limited, but an aliphatic hydrocarbon is preferred. The aliphatic hydrocarbon may be linear or branched. Furthermore, the aliphatic hydrocarbon may be saturated or unsaturated.

[0058] The 1,3-diene compound is preferably one or more selected from the group consisting of isoprene, myrcene, and farnesene, and more preferably myrcene and / or farnesene. The farnesene may be either α-farnesene or β-farnesene. α-farnesene and β-farnesene may be used in combination. The 1,3-diene compound may be used alone or in combination of two or more.

[0059] The structural units derived from the 1,3-diene compound can have a 1,2 configuration represented by the following formula (1), a 3,4 configuration represented by the following formula (2), or a 1,4 configuration represented by the following formula (3). The structural units derived from the 1,3-diene compound of the branched conjugated diene copolymer contained in the rubber composition according to this embodiment preferably include the 3,4 configuration represented by the following formula (2). The 3,4 configuration preferably accounts for 10 mol% or more, more preferably 15 mol% or more, and even more preferably 20 mol% or more of the total structural units derived from the 1,3-diene compound.

[0060] [ka]

[0061] The content of structural units derived from 1,3-diene compounds in the branched conjugated diene copolymer contained in the rubber composition according to this embodiment is preferably 5 mol% or more, more preferably 8 mol% or more, even more preferably 10 mol% or more, and particularly preferably 12 mol% or more, from the viewpoint of improving compatibility with other rubber components and co-crosslinkability with tire adjacent members. Furthermore, from the viewpoint of the effects of the present invention, the content of structural units derived from 1,3-diene compounds is preferably 40 mol% or less, more preferably 30 mol% or less, and even more preferably 20 mol% or less.

[0062] The branched conjugated diene copolymer contained in the rubber composition according to the present embodiment may contain other monomer units, such as butadiene units, aromatic vinyl units, and non-conjugated olefin units.

[0063] The aromatic vinyl unit refers to a structural unit in a copolymer derived from an aromatic vinyl compound. Here, the aromatic vinyl compound refers to an aromatic compound substituted with at least a vinyl group. Examples of aromatic vinyl compounds include styrene, α-methylstyrene, 1-vinylnaphthalene, 3-vinyltoluene, ethylvinylbenzene, divinylbenzene, 4-cyclohexylstyrene, and 2,4,6-trimethylstyrene, with styrene being preferred. These compounds may be used alone or in combination of two or more.

[0064] The term "non-conjugated olefin unit" refers to a structural unit in a copolymer derived from a non-conjugated olefin compound. Here, the term "non-conjugated olefin compound" refers to an unsaturated aliphatic hydrocarbon, a non-conjugated compound having one or more carbon-carbon double bonds. Examples of non-conjugated olefin compounds include α-olefins such as propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, and 1-octene; heteroatom-substituted alkene compounds such as vinyl pivalate, 1-phenylthioethene, and N-vinylpyrrolidone; and the like; with 1-butene being preferred. These compounds may be used alone or in combination of two or more.

[0065] The branched conjugated diene copolymer contained in the rubber composition according to the present embodiment can be treated with a modifier to form a modified product having a functional group that interacts with the filler. Any functional group commonly used in this field can be suitably used, such as an alkoxysilyl group (e.g., trimethoxysilyl group, triethoxysilyl group). For example, if the copolymer is treated with chlorotriethoxysilane as a modifier before hydrogenation after synthesis, a modified product having a triethoxysilyl group introduced at the active end of the copolymer can be obtained.

[0066] The glass transition temperature of the branched conjugated diene copolymer contained in the rubber composition according to this embodiment is preferably −90° C. or higher, more preferably −85° C. or higher, even more preferably −80° C. or higher, even more preferably −75° C. or higher, and particularly preferably −70° C. or higher. The glass transition temperature is preferably −10° C. or lower, more preferably −15° C. or lower, even more preferably −18° C. or lower, even more preferably −20° C. or lower, and particularly preferably −22° C. or lower. The glass transition temperature of the copolymer is determined by the above-mentioned measurement method.

[0067] The weight average molecular weight (Mw) of the branched conjugated diene copolymer contained in the rubber composition according to this embodiment is preferably 100,000 or more, more preferably 150,000 or more, and even more preferably 200,000 or more. From the viewpoint of crosslink uniformity, the weight average molecular weight is preferably 2,000,000 or less, more preferably 1,800,000 or less, and even more preferably 1,500,000 or less. In this specification, the weight average molecular weight of the copolymer is measured by the above-mentioned measurement method.

[0068] The Mw of the copolymer can be controlled by a conventional method, for example, by adjusting the amount of each monomer added during polymerization relative to the catalyst. For example, the Mw can be increased by increasing the ratio of total monomers to anionic polymerization catalyst or total monomers to coordination polymerization catalyst, and conversely, the Mw can be decreased by decreasing the ratio.

[0069] The branched conjugated diene copolymer contained in the rubber composition according to the present embodiment can be produced by subjecting each monomer component to a copolymerization reaction using a conventional method, such as anionic polymerization or coordination polymerization, to form a copolymer. Furthermore, the copolymer can also be produced by hydrogenating the copolymer to form a hydrogenated product. The hydrogenation reaction of the branched conjugated diene can be carried out using a conventional method, and catalytic hydrogenation using a metal catalyst or a method using hydrazine can both be suitably used. For example, catalytic hydrogenation using a metal catalyst can be carried out by adding hydrogen under pressure in an organic solvent in the presence of a metal catalyst. Suitable organic solvents include tetrahydrofuran, methanol, and ethanol. These organic solvents can be used alone or in combination of two or more. Suitable metal catalysts include palladium, platinum, rhodium, ruthenium, and nickel. These metal catalysts can be used alone or in combination of two or more. The pressure during pressurization can be, for example, 1 to 300 kgf / cm. 2 It is preferable that:

[0070] The branched conjugated diene copolymer was confirmed to have ethylene units and structural units derived from a 1,3-diene compound by gel permeation chromatography (GPC), 1 H-NMR, 13 This can be done using techniques such as C-NMR. 1 H-NMR spectrum and 13 Based on the C-NMR spectrum, the presence of units derived from each monomer component can be confirmed.

[0071] The copolymerization reaction is not particularly limited in the order of copolymerization, as long as it copolymerizes each monomer component. For example, all monomers may be randomly copolymerized at once, or specific monomers may be copolymerized in advance and then the remaining monomers may be added and copolymerized, or specific monomers may be copolymerized in advance and then block copolymerized. Random copolymerization is preferred. The polymerization method is also not particularly limited, and any of solution polymerization, emulsion polymerization, gas phase polymerization, bulk polymerization, etc. can be used, but solution polymerization is preferred. The polymerization method may be either batch or continuous.

[0072] The content C of the branched conjugated diene copolymer in the rubber component SW From the viewpoint of the effects of the present invention, the content of C is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, still more preferably 25% by mass or more, still more preferably 30% by mass or more, still more preferably 35% by mass or more, and particularly preferably 40% by mass or more. SW is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 65% ​​by mass or less.

[0073] (BR) The BR is not particularly limited, and can be one commonly used in the tire industry, such as 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 butadiene rubber (rare earth BR) synthesized using a rare earth catalyst, BR containing syndiotactic polybutadiene crystals (SPB-containing BR), modified BR (high-cis modified BR, low-cis modified BR), etc. These BRs may be used alone or in combination of two or more.

[0074] As the high-cis BR, for example, commercially available products from Zeon Corporation, UBE Corporation, JSR Corporation, etc. can be used. The inclusion of high-cis BR can improve low-temperature properties and wear resistance. The cis content of the high-cis BR is preferably more than 95 mol%, more preferably more than 96 mol%, and even more preferably more than 97 mol%. The cis content of BR is measured by the above-mentioned measurement method.

[0075] The rare earth BR is synthesized using a rare earth catalyst and has a vinyl content of preferably less than 1.8 mol%, more preferably less than 1.6 mol%, and even more preferably 1.5 mol% or less, and a cis content of preferably more than 95 mol%, more preferably more than 96 mol%, and even more preferably 97 mol% or more. As the rare earth BR, for example, commercially available products from LANXESS K.K. can be used.

[0076] The SPB-containing BR is not simply 1,2-syndiotactic polybutadiene crystals dispersed in the BR, but is dispersed after being chemically bonded to the BR. As such SPB-containing BR, commercially available products from UBE Corporation and the like can be used.

[0077] Examples of modified BR include BR modified with functional groups similar to those described above for SBR, and also preferably used are modified butadiene rubbers (modified BRs) whose terminals and / or main chains are modified with functional groups containing at least one element selected from the group consisting of silicon, nitrogen, and oxygen.

[0078] Other examples of modified BR include tin-modified BR, which is obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound, and in which the terminals of the modified BR molecule are further bonded with a tin-carbon bond (tin-modified BR).Modified BR may be either non-hydrogenated or hydrogenated.

[0079] From the viewpoint of abrasion resistance, the weight-average molecular weight (Mw) of BR is preferably more than 300,000, more preferably more than 350,000, and even more preferably more than 400,000. From the viewpoint of crosslink uniformity, etc., it is preferably less than 2,000,000, more preferably less than 1,000,000, and even more preferably less than 700,000. Mw can be determined by the above-mentioned method.

[0080] From the viewpoint of the effects of the present invention, the content of BR in the rubber component is preferably 1.0% by mass or more, more preferably 5.0% by mass or more, even more preferably 10% by mass or more, and particularly preferably 20% by mass or more. The content of BR in the rubber component is preferably 70% by mass or less, more preferably 65% ​​by mass or less, and even more preferably 61% by mass or less.

[0081] (Other rubber components) The rubber component may contain isoprene-based rubber, the branched conjugated rubber, or the like within a range that does not affect the effects of the present invention. The rubber composition may contain rubber components other than the diene copolymer and BR. Examples of other rubber components include rubber components commonly used in the tire industry, such as SBR, ethylene propylene rubber, polynorbornene rubber, silicone rubber, chlorinated polyethylene rubber, fluororubber (FKM), acrylic rubber (ACM), and hydrin rubber. These other rubber components may be used alone or in combination of two or more. In addition to the above rubber components, the rubber composition may or may not contain a known thermoplastic elastomer.

[0082] (SBR) The SBR is not particularly limited, and examples thereof include solution-polymerized SBR (S-SBR), emulsion-polymerized SBR (E-SBR), and modified SBRs thereof (modified S-SBR, modified E-SBR). Modified SBRs include SBRs whose terminals and / or main chains have been modified with compounds (modifiers) having the functional groups listed below; modified SBRs (condensates, those having a branched structure, etc.) coupled with tin, silicon compounds, etc. Furthermore, hydrogenated products of these SBRs (hydrogenated SBRs) can also be used. These SBRs may be used alone or in combination of two or more.

[0083] When SBR is contained, the amount of SBR per 100 parts by mass of the rubber component is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less.

[0084] (Rubber components synthesized from recycled and biomass-derived raw materials) Monomers, which are structural units of synthetic rubbers such as IR, SBR, and BR, may be derived from underground resources such as petroleum and natural gas, or may be recycled from rubber products such as tires or non-rubber products such as polystyrene. Monomers obtained by recycling (recycled monomers) are not particularly limited, and examples include recycled polyisoprene, recycled butadiene, and recycled aromatic vinyl compounds. Examples of butadienes include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyl compounds include, but are not limited to, styrene. Among these, recycled polyisoprene (recycled isoprene), recycled butadiene (recycled butadiene), and / or recycled styrene (recycled styrene) are preferably used as raw materials.

[0085] The method for producing the recycled monomer is not particularly limited, and examples thereof include synthesis from recycled naphtha obtained by decomposing rubber products such as tires. The method for producing recycled naphtha is also not particularly limited, and examples thereof include decomposing rubber products such as tires under high temperature and pressure, decomposing with microwaves, or mechanically crushing and then extracting.

[0086] Furthermore, the monomers that are the structural units of polymers such as IR, SBR, and BR may be derived from biomass. In this specification, biomass refers to materials derived from natural resources such as plants. Examples of biomass include, but are not limited to, agricultural, forestry, and fishery products, sugar, wood chips, plant residues after useful components have been extracted, plant-derived ethanol, and biomass naphtha.

[0087] Monomers derived from biomass (biomass monomers) are not particularly limited, and examples thereof include biomass-derived butadiene and biomass-derived aromatic vinyl compounds. Examples of butadienes include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyl compounds include, but are not limited to, styrene. The method for producing biomass monomers is not particularly limited, and examples include biological and / or chemical and / or physical conversion of animals and plants. A representative example of biological conversion is fermentation by microorganisms, and examples of chemical and / or physical conversion include catalytic, high-temperature, high-pressure, electromagnetic, and critical fluid conversion, as well as combinations thereof.

[0088] Polymers synthesized from biomass monomer components (biomass polymers) are not particularly limited and include polybutadiene rubber synthesized from biomass-derived butadiene, aromatic vinyl / butadiene copolymers synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl compounds, etc. Examples of the aromatic vinyl / butadiene copolymers include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0089] Whether a polymer's raw material is biomass-derived can be determined by its pMC (percent modern carbon) measured in accordance with ASTM D 6866-10. pMC is the modern standard reference carbon. 14 of sample against C concentration 14 This is the ratio of C concentrations and is a value used as an index of the biomass ratio of a compound. The significance of this value is explained below.

[0090] 1 mole of carbon atoms (6.02 × 10 23 ) contains approximately 6.02 × 10 atoms, which is about one trillionth of the number of ordinary carbon atoms. 11 pieces 14C exists. 14 The half-life of C is 5730 years, 14 C is decreasing regularly. Therefore, in the case of fossil fuels such as coal, oil, and natural gas, which are thought to have been absorbed and fixed by plants and other organisms more than 226,000 years ago, C was also included in these when they were first fixed. 14 All C elements have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas contain 14 Therefore, chemicals produced from these fossil fuels do not contain any C element. 14 It does not contain any C elements.

[0091] on the other hand, 14 C is constantly produced by cosmic rays undergoing nuclear reactions in the atmosphere. 14 The amount of C is balanced between radioactive decay and nuclear reaction, and in the Earth's atmospheric environment, 14 Therefore, the amount of carbon derived from biomass resources currently circulating in the environment is constant. 14 As mentioned above, the C concentration is approximately 1 × 10 -12 The value is approximately mol %. Therefore, the biomass ratio in a compound can be calculated by using the difference between these values.

[0092] this 14 C is typically measured using accelerator mass spectrometry based on a tandem accelerator. 13 C concentration ( 13 C / 12 C). 14 C concentration ( 14 C / 12 C) is measured. 14 The modern standard reference for the C concentration is the carbon circulating in nature as of 1950. 14The specific standard substance used is the oxalic acid standard provided by NIST (National Institute of Standards and Technology). The specific activity of carbon in this oxalic acid (per gram of carbon) is 14 The radioactivity of C is separated into carbon isotopes, 13 The standard value is the value corrected for decay from 1950 to the measurement date. 14 This is used as the C concentration value (100%). The ratio of this value to the value of the actually measured sample is the pMC value.

[0093] Therefore, if rubber is made from 100% biomass-derived materials, although there are regional differences, it will usually not reach 100 under normal conditions, so it will show a value of approximately 110 pMC. On the other hand, for chemical substances derived from petroleum and other fossil fuels, 14 When the carbon concentration is measured, it will show a value of about 0 pMC (for example, 0.3 pMC), which corresponds to the biomass ratio of 0% mentioned above.

[0094] From the above, it is preferable in terms of environmental protection to use a material such as rubber having a high pMC value, that is, a material such as rubber having a high biomass ratio, in a rubber composition.

[0095] [Filler] The rubber composition according to the present embodiment preferably contains carbon black as a filler, but the filler may also be composed solely of carbon black.

[0096] <Carbon black> Carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. The raw material for carbon black may be a biomass material such as lignin or vegetable oil, or pyrolysis oil obtained by pyrolysis of waste tires. Carbon black may be produced by combustion, such as in a furnace process, by hydrothermal carbonization (HTC), or by thermal decomposition of methane, such as in a thermal black process. Commercially available carbon black products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., and Columbia Carbon Co., Ltd. One type of carbon black may be used alone, or two or more types may be used in combination.

[0097] In addition to the above, from the viewpoint of life cycle assessment, carbon black may be made from a biomass material such as lignin, or recycled carbon black obtained by pyrolysis and purification of a product containing carbon black, such as a tire.

[0098] As used herein, "recycled carbon black" refers to carbon black obtained by crushing used tires or other products containing carbon black and calcining the crushed material, and refers to carbon black in which, when subjected to oxidative combustion by heating in air as measured by thermogravimetry in accordance with JIS K 6226-2:2003, the proportion of the mass of ash (ash content), which is the non-combustible component, is 13% by mass or more. In other words, the proportion of the mass (carbon content) of the recycled carbon black lost due to oxidative combustion is 87% by mass or less. Recycled carbon black is sometimes expressed as rCB.

[0099] Recycled carbon black can be obtained from the pyrolysis process of used pneumatic tires. For example, European Patent Application Publication No. 3427975, citing "Rubber Chemistry and Technology," Vol. 85, No. 3, pp. 408-449 (2012), particularly pp. 438, 440, and 442, describes the carbon black as being obtained by pyrolysis of organic materials at 550-800°C in the absence of oxygen, or by vacuum pyrolysis at relatively low temperatures (

[0027] ). Carbon black obtained from such pyrolysis processes typically lacks functional groups on its surface, as mentioned in

[0004] of Japanese Patent Publication No. 6856781 (Comparison of the Surface Morphology and Chemistry of Pyrolytic Carbon Black with Commercial Carbon Black, Powder Technology 160 (2005) pp. 190-193).

[0100] Recycled carbon black may lack functional groups on its surface, or may be treated to include functional groups on its surface. Treatment to include functional groups on the surface of recycled carbon black can be carried out by conventional methods. For example, in European Patent Application Publication No. 3,173,251, carbon black obtained from a pyrolysis process is treated with potassium permanganate under acidic conditions to obtain carbon black containing hydroxyl and / or carboxyl groups on its surface. Furthermore, in Japanese Patent Publication No. 6,856,781, carbon black obtained from a pyrolysis process is treated with an amino acid compound containing at least one thiol or disulfide group to obtain surface-activated carbon black. The recycled carbon black of this embodiment also includes carbon blacks treated to include functional groups on their surfaces.

[0101] As the recycled carbon black, commercially available products from Strable Green Carbon, LD Carbon, etc. can be used.

[0102] The nitrogen adsorption specific surface area (N2SA) of carbon black is 80m from the viewpoint of reinforcement. 2 / g or more is preferable, and 90m2 / g or more is more preferable, and 100m 2 / g or more is more preferable, and 110m 2 From the viewpoint of heat buildup and processability, it is particularly preferable that the tensile strength is 200 m / g or more. 2 / g or less is preferable, and 180m 2 / g or less is more preferable, and 140m 2 / g or less is more preferable. The N2SA of carbon black is measured by the above-mentioned measurement method.

[0103] From the viewpoint of the effects of the present invention, the average primary particle diameter of carbon black is preferably 50 nm or less, more preferably 40 nm or less, even more preferably 30 nm or less, and particularly preferably 25 nm or less. The average primary particle diameter is preferably 15 nm or more, more preferably 18 nm or more, and even more preferably 20 nm or more. The average primary particle diameter of carbon black is measured by the above-mentioned measurement method.

[0104] The amount of carbon black per 100 parts by mass of the rubber component is preferably more than 10 parts by mass, more preferably more than 20 parts by mass, even more preferably more than 30 parts by mass, still more preferably more than 40 parts by mass, and particularly preferably 50 parts by mass or more. The amount is preferably less than 100 parts by mass, more preferably less than 80 parts by mass, and even more preferably less than 70 parts by mass.

[0105] <Other fillers> The filler may contain fillers other than carbon black. The other fillers are not particularly limited, but may include, for example, silica, aluminum hydroxide, calcium carbonate, alumina, clay, talc, and other fillers that have been commonly used in the tire industry.

[0106] <Silica> The silica is not particularly limited, and can be, for example, silica prepared by a dry method (anhydrous silica), silica prepared by a wet method (hydrated silica), or other silica commonly used in the tire industry. The raw material for silica is also not particularly limited, and can be, for example, a mineral-derived raw material such as quartz, a biological raw material such as rice husk (for example, silica made from biomass materials such as rice husk), or silica recycled from silica-containing products. Among these, hydrated silica prepared by a wet method is preferred because it contains a large number of silanol groups. These silicas can be used alone or in combination of two or more types.

[0107] Silica made from biomass materials can be obtained, for example, by extracting silicate from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and then reacting the silicate with sulfuric acid in the same manner as conventional wet-process silica to produce a silicon dioxide precipitate, which is then filtered, washed with water, dried, and pulverized.

[0108] Silica recycled from silica-containing products can be, for example, silica recovered from products containing silica, such as electronic components such as semiconductors, tires, desiccants, and filtering materials such as diatomaceous earth. The recovery method is not particularly limited, and examples include thermal decomposition and decomposition by electromagnetic waves. Among these, silica recovered from electronic components such as semiconductors or tires is preferred.

[0109] When silica crystallizes, it becomes insoluble in water, and its component, silicic acid, cannot be utilized. By controlling the combustion temperature and duration, the crystallization of silica in rice husk ash can be suppressed (see, for example, JP 2009-2594 A, Akita Prefectural University Web Journal B / 2019, vol. 6, pp. 216-222). Amorphous silica extracted from rice husks can be commercially available from Wilmar, Inc.

[0110] (Silane coupling agent) Silica is preferably used in combination with a silane coupling agent.The silane coupling agent is not particularly limited, and any silane coupling agent that has been conventionally used in combination with silica in the tire industry can be used, for example, the following mercapto-based silane coupling agents: sulfide-based silane coupling agents such as bis(3-triethoxysilylpropyl) disulfide, bis(3-triethoxysilylpropyl) tetrasulfide; thioester-based silane coupling agents such as 3-octanoylthio-1-propyltriethoxysilane, 3-hexanoylthio-1-propyltriethoxysilane, 3-octanoylthio-1-propyltrimethoxysilane; vinyltriethoxysilane, ... Examples of suitable silane coupling agents include vinyl-based silane coupling agents such as methoxysilane; 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; and chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Among these, sulfide-based silane coupling agents and / or mercapto-based silane coupling agents are preferred. These silane coupling agents may be used alone or in combination.

[0111] [Other compounding agents] In addition to the rubber component and filler, the rubber composition according to the present embodiment may contain compounding agents that are generally used in the tire industry, such as plasticizers, processing aids, vulcanized rubber particles, wax, stearic acid, zinc oxide, antioxidants, vulcanizing agents, and vulcanization accelerators.

[0112] <Plasticizer> A plasticizer is a material that imparts plasticity to rubber components, and the term encompasses both plasticizers that are liquid at 25°C and plasticizers that are solid at 25°C. Examples of plasticizers include oils, resin components, liquid rubber, and ester-based plasticizers. These plasticizers may be derived from mineral resources such as petroleum and natural gas, or may be derived from biomass. Low-molecular-weight hydrocarbon components obtained by pyrolysis and extraction of used tires or products containing various components may also be used as plasticizers. One type of plasticizer may be used alone, or two or more types may be used in combination.

[0113] (oil) Examples of oils include mineral oil, vegetable oil, and animal oil. From the viewpoint of life cycle assessment, waste oils used in rubber mixers and engines, and refined waste cooking oils used in restaurants may also be used. One type of oil may be used alone, or two or more types may be used in combination.

[0114] As used herein, mineral oil refers to oil derived from mineral resources such as petroleum and natural gas. Examples of mineral oil include paraffinic oil (mineral oil), naphthenic oil, and aromatic oil. Specific examples of mineral oil include mild extracted solvate (MES), distillate aromatic extract (DAE), treated distillate aromatic extract (TDAE), treated residual aromatic extract (TRAE), and residual aromatic extract (RAE). Furthermore, as an environmental measure, oils with a low content of polycyclic aromatic compounds (PCA) can also be used. Examples of low PCA oils include MES, TDAE, and heavy naphthenic oil.

[0115] In this specification, examples of vegetable oils include linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar oil, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grapeseed oil, and Japan wax. Further examples of vegetable oils include refined oils (such as salad oil) obtained by refining the above oils, interesterified oils obtained by interesterifying the above oils, hardened oils obtained by hydrogenating the above oils, thermally polymerized oils obtained by thermally polymerizing the above oils, oxidatively polymerized oils obtained by oxidizing the above oils, and waste edible oils recovered from edible oils. Vegetable oils may be liquid or solid at room temperature (25°C).

[0116] The vegetable oil according to this embodiment preferably contains acylglycerol, and more preferably triacylglycerol. In this specification, acylglycerol refers to a compound in which a hydroxyl group of glycerin is ester-bonded to a fatty acid. The acylglycerol is not particularly limited and may be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Furthermore, the acylglycerol may be a monomer, a dimer, or a polymer (trimer or higher). Dimer or higher acylglycerols can be obtained by thermal polymerization, oxidative polymerization, or the like. Furthermore, the acylglycerol may be liquid or solid at room temperature (25°C).

[0117] The method for confirming whether the rubber composition contains the acylglycerol is not particularly limited, but may be any of the following: 1 For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at room temperature (25°C) for 24 hours, and after removing the rubber composition, the rubber composition is immersed in deuterated chloroform at room temperature. 1When H-NMR was measured, signals were observed around 5.26 ppm, 4.28 ppm, and 4.15 ppm when the signal of tetramethylsilane (TMS) was set at 0.00 ppm. These signals are presumed to be signals derived from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atoms of the ester group. In this paragraph, "around" refers to a range of ±0.10 ppm.

[0118] The fatty acid is not particularly limited and may be either an unsaturated fatty acid or a saturated fatty acid. Examples of unsaturated fatty acids include monounsaturated fatty acids such as oleic acid, and polyunsaturated fatty acids such as linoleic acid and linolenic acid. Examples of saturated fatty acids include butyric acid and lauric acid.

[0119] Among these, it is desirable that the fatty acid contains a fatty acid with few double bonds, i.e., a saturated fatty acid or a monounsaturated fatty acid, and oleic acid is preferred. As a vegetable oil containing such a fatty acid, for example, vegetable oil containing a saturated fatty acid or a monounsaturated fatty acid may be used, or vegetable oil modified by ester exchange or the like may be used. Furthermore, in order to produce a vegetable oil containing such a fatty acid, plants may be improved by breeding, genetic modification, or the like.

[0120] As the vegetable oil, for example, commercially available products from Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoi Co., Ltd., H&R Corporation, Toyokuni Oil Mills Co., Ltd., Fuji Kosan Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0121] Examples of animal oils include fish oil, beef tallow, and oleyl alcohol derived from these.

[0122] The oil content per 100 parts by mass of the rubber component is preferably more than 5 parts by mass, more preferably more than 8 parts by mass, and even more preferably 10 parts by mass or more from the viewpoint of processability. Furthermore, from the viewpoint of abrasion resistance, the oil content is preferably less than 50 parts by mass, more preferably less than 30 parts by mass, and even more preferably less than 20 parts by mass. The plasticizer content also includes the amount of extension plasticizers, such as extension oil, extension resin, extension liquid rubber component, and extension ester-based plasticizer, used to extend the rubber component.

[0123] (resin component) Among the other compounding ingredients, the rubber composition preferably contains a resin component. The resin component is not particularly limited, but resins commonly used in the tire industry can be used, such as aromatic vinyl resins, dicyclopentadiene resins, C9 resins, C5 resins, C5C9 resins, terpene resins, rosin resins, and phenolic resins. Of these, aromatic vinyl resins, C9 resins, and terpene resins are preferred. The resin component may be used alone or in combination of two or more.

[0124] (liquid rubber) The liquid rubber is not particularly limited as long as it is a polymer that is in a liquid state at room temperature (25°C), and examples thereof include liquid butadiene rubber (liquid BR), liquid styrene butadiene rubber (liquid SBR), liquid isoprene rubber (liquid IR), liquid styrene isoprene rubber (liquid SIR), liquid farnesene rubber, etc. One type of liquid rubber may be used alone, or two or more types may be used in combination.

[0125] (ester plasticizer) Examples of ester-based plasticizers include 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), diundecyl phthalate (DUP), dibutyl phthalate (DBP), dioctyl sebacate (DOS), tributyl phosphate (TBP), trioctyl phosphate (TOP), triethyl phosphate (TEP), trimethyl phosphate (TMP), thymidine triphosphate (TTP), tricresyl phosphate (TCP), and trixylenyl phosphate (TXP). One type of ester-based plasticizer may be used alone, or two or more types may be used in combination.

[0126] (wax) From the viewpoint of ozone resistance, the rubber composition according to the present embodiment preferably contains a wax. The wax is not particularly limited, and any wax commonly used in the tire industry can be suitably used, such as mineral waxes and plant-derived waxes. Mineral waxes refer to waxes derived from mineral resources such as oil and natural gas. Plant-derived waxes refer to waxes derived from natural resources such as plants. Mineral waxes are particularly preferred. Examples of plant-derived waxes include rice wax, carnauba wax, and candelilla wax. Examples of mineral waxes include paraffin wax, microcrystalline wax, and selected special waxes thereof, with paraffin wax being preferred. The wax according to the present embodiment does not contain stearic acid. Commercially available waxes, for example, from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Paramelt Co., Ltd., can be used. One wax may be used alone, or two or more waxes may be used in combination.

[0127] The content of the wax per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 0.8 parts by mass or more, and even more preferably 1.0 part by mass or more, from the viewpoint of ozone resistance and weather resistance of the rubber, and is preferably less than 10 parts by mass, more preferably less than 7.0 parts by mass, and even more preferably less than 5.0 parts by mass, from the viewpoint of preventing whitening of the tire due to bloom.

[0128] (vulcanized rubber particles) The vulcanized rubber particles are particles made of vulcanized rubber, and specifically, rubber powder as specified in JIS K 6316:2017 can be used. From the standpoint of environmental considerations and cost, recycled rubber powder produced from crushed waste tires is preferred. One type of vulcanized rubber particle may be used alone, or two or more types may be used in combination.

[0129] The vulcanized rubber particles are not particularly limited, and may be unmodified vulcanized rubber particles or modified vulcanized rubber particles.

[0130] As commercially available vulcanized rubber, for example, products from Lehigh, Muraoka Rubber Industries, Ltd., etc. can be used.

[0131] (processing aids) Examples of processing aids include fatty acid metal salts, fatty acid amides, amide esters, silica surfactants, mixtures of fatty acid metal salts and amide esters, and mixtures of fatty acid metal salts and fatty acid amides. These processing aids may be used alone or in combination of two or more. Examples of processing aids that can be used include those commercially available from Schill + Seilacher, Performance Additives, etc.

[0132] When a processing aid is contained, the content thereof per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.0 parts by mass, and even more preferably more than 1.5 parts by mass from the viewpoint of improving processability, and is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and even more preferably less than 5.0 parts by mass from the viewpoint of abrasion resistance and breaking strength.

[0133] (stearic acid) When stearic acid is contained, the content per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 parts by mass from the viewpoint of processability, and is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and even more preferably less than 5.0 parts by mass from the viewpoint of vulcanization rate.

[0134] (zinc oxide) When zinc oxide is contained, the content per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 parts by mass from the viewpoint of processability, and preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and even more preferably less than 5.0 parts by mass from the viewpoint of abrasion resistance.

[0135] (anti-aging agent) The antioxidant is not particularly limited, but examples thereof include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), N,N'-ditolyl ... p-phenylenediamine-based antioxidants such as diphenyldiamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline-based antioxidants such as 2,2,4-trimethyl-1,2-dihydroquinoline polymers; monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol-based antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Among these, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferred, and polymers of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. Commercially available products that can be used include those from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., and Flexis Co., Ltd. One type of antioxidant may be used alone, or two or more types may be used in combination.

[0136] When an antioxidant is contained, the content per 100 parts by mass of the rubber component is preferably more than 0.8 parts by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 parts by mass from the viewpoint of ozone crack resistance of the rubber, and is preferably less than 5.0 parts by mass, more preferably less than 4.0 parts by mass, and even more preferably less than 3.5 parts by mass from the viewpoint of abrasion resistance and wet grip performance.

[0137] (vulcanizing agent) Sulfur is preferably used as the vulcanizing agent. Examples of sulfur that can be used include powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur. The vulcanizing agent may be used alone or in combination of two or more.

[0138] When sulfur is contained, the content per 100 parts by mass of the rubber component is preferably more than 0.5 parts by mass, more preferably more than 0.8 parts by mass, even more preferably more than 1.0 parts by mass, and particularly preferably more than 1.2 parts by mass, from the viewpoint of ensuring a sufficient vulcanization reaction. Furthermore, from the viewpoint of preventing deterioration, the content is preferably less than 5.0 parts by mass, more preferably less than 4.0 parts by mass, even more preferably less than 3.0 parts by mass, and particularly preferably less than 2.0 parts by mass. When oil-containing sulfur is used as the vulcanizing agent, the content of the vulcanizing agent is the total content of pure sulfur contained in the oil-containing sulfur.

[0139] Known organic crosslinking agents can also be used as vulcanizing agents other than sulfur. The organic crosslinking agent is not particularly limited as long as it can form crosslinked chains other than polysulfide bonds. Examples of the organic crosslinking agent include alkylphenol-sulfur chloride condensate, sodium 1,6-hexamethylene-dithiosulfate dihydrate, 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane, and dicumyl peroxide. 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane is preferred. These organic crosslinking agents can be commercially available from Taoka Chemical Co., Ltd., Lanxess K.K., Flexis, and other companies.

[0140] (Vulcanization accelerator) The vulcanization accelerator is not particularly limited, but examples thereof include sulfenamide vulcanization accelerators, thiazole vulcanization accelerators, guanidine vulcanization accelerators, thiuram vulcanization accelerators, thiourea vulcanization accelerators, dithiocarbamate vulcanization accelerators, aldehyde-amine vulcanization accelerators, aldehyde-ammonia vulcanization accelerators, imidazoline vulcanization accelerators, xanthate vulcanization accelerators, and caprolactam disulfide. These vulcanization accelerators may be used alone or in combination of two or more. Among them, one or more vulcanization accelerators selected from the group consisting of sulfenamide vulcanization accelerators, thiazole vulcanization accelerators, and guanidine vulcanization accelerators are preferred, as they more suitably achieve the desired effects. The vulcanization accelerators may be used alone or in combination of two or more.

[0141] Examples of sulfenamide vulcanization accelerators include N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), and N,N-dicyclohexyl-2-benzothiazolylsulfenamide (DCBS).

[0142] Examples of thiazole vulcanization accelerators include 2-mercaptobenzothiazole (MBT) or a salt thereof, di-2-benzothiazolyl disulfide (MBTS), 2-(2,4-dinitrophenyl)mercaptobenzothiazole, and 2-(2,6-diethyl-4-morpholinothio)benzothiazole.

[0143] Examples of guanidine vulcanization accelerators include 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salt of dicatechol borate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, and 1,3-di-o-cumenyl-2-propionylguanidine.

[0144] Examples of thiuram vulcanization accelerators include tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N), tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide, tetramethylthiuram monosulfide (TMTM), dipentamethylene thiuram disulfide, and dipentamethylene thiuram tetrasulfide.

[0145] Examples of the thiourea vulcanization accelerator include thiourea compounds such as thiacarbamide, diethylthiourea, dibutylthiourea, trimethylthiourea and diorthotolylthiourea, N,N'-diphenylthiourea, trimethylthiourea and N,N'-diethylthiourea.

[0146] Examples of dithiocarbamate vulcanization accelerators include piperidinium pentamethylenedithiocarbamate (PPDC), zinc dimethyldithiocarbamate (ZnMDC), zinc diethyldithiocarbamate (ZnEDC), zinc dibutyldithiocarbamate (ZnBDC), zinc dibenzyldithiocarbamate (ZDBzC), zinc N-ethyl-N-phenyldithiocarbamate (ZnEPDC), zinc N-pentamethylenedithiocarbamate (ZnPDC), sodium dibutyldithiocarbamate (NaBDC), copper dimethyldithiocarbamate (CuMDC), iron dimethyldithiocarbamate (FeMDC), and tellurium diethyldithiocarbamate (TeEDC).

[0147] When a vulcanization accelerator is contained, the content thereof (total amount when multiple vulcanization accelerators are used) per 100 parts by mass of the rubber component is preferably more than 1.0 part by mass, more preferably more than 1.5 parts by mass, and even more preferably more than 2.0 parts by mass. The content of the vulcanization accelerator per 100 parts by mass of the rubber component is preferably less than 8.0 parts by mass, more preferably less than 6.0 parts by mass, and even more preferably less than 5.0 parts by mass.

[0148] In this specification, various materials containing carbon atoms (e.g., rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from atmospheric carbon dioxide. As a method for obtaining a blend of the various materials from carbon dioxide, carbon dioxide may be directly converted, or methane obtained through a methanation process in which methane is synthesized from carbon dioxide may be converted.

[0149] [Manufacturing] The rubber composition can be produced by a known method, for example, by kneading the above-mentioned components using a rubber kneading device such as an open roll or an internal kneader (such as a Banbury mixer or kneader).

[0150] The kneading process may include, for example, a base kneading process in which compounding ingredients and additives other than the vulcanizing agent and vulcanization accelerator are kneaded, and a final kneading (F kneading) process in which the vulcanizing agent and vulcanization accelerator are added to the kneaded product obtained in the base kneading process and kneaded. Furthermore, the base kneading process may be divided into multiple processes as desired. When the base kneading process is divided, the method may be (1) a method in which some of the compounding ingredients and additives are pre-mixed to form a masterbatch, and then the remaining compounding ingredients and additives are added to the resulting masterbatch and kneaded, or (2) a method in which all of the compounding ingredients and additives to be kneaded in the base kneading process are kneaded at once, and then the kneaded product is remilled one or more times. In the above method (1), the number of masterbatches is not limited and may be two or more. Furthermore, when the number of masterbatches is two or more, all of the compounding ingredients and additives used in the base kneading process may be allocated to one of the masterbatches.

[0151] The kneading conditions are not particularly limited, but examples include a method in which the base kneading step involves kneading for 3 to 10 minutes at a discharge temperature of 150 to 170°C, and a method in which the final kneading step involves kneading for 1 to 5 minutes at 70 to 110°C. The vulcanization conditions are not particularly limited, but examples include a method in which vulcanization is carried out for 10 to 30 minutes at 150 to 200°C.

[0152] A tire having a sidewall made of a rubber composition can be manufactured by a conventional method. That is, the tire can be manufactured by extruding an unvulcanized rubber composition prepared by blending the above-mentioned components with a rubber component as needed to form a sidewall shape, laminating and molding the sidewall thus obtained together with other tire components in a tire building machine by a conventional method to form an unvulcanized tire, and then heating and pressurizing the unvulcanized tire thus obtained in a vulcanizer. The vulcanization conditions are not particularly limited, and examples include a method of vulcanizing at 150 to 200°C for 10 to 30 minutes.

[0153] [Application] The tire of this embodiment can be used for any purpose, regardless of whether it is a pneumatic tire or a non-pneumatic tire, and can be used as a passenger car tire, a large passenger car tire, a large SUV tire, a racing tire, a motorcycle tire, a heavy-duty tire, or a run-flat tire. Passenger car tires are tires designed to be mounted on four-wheeled vehicles and have a maximum load capacity of less than 1,400 kg. Heavy-duty tires are tires with a maximum load capacity of 1,400 kg or more. The tire of this embodiment can be used as an all-season tire, a summer tire, or a winter tire such as a studless tire. [Example]

[0154] The following examples (working examples) are considered to be preferable for carrying out the present invention, but the scope of the present invention is not limited to these working examples. Tires obtained according to Table 1 using the various chemicals shown below were examined, and the results calculated based on the evaluation method below are shown in Table 1.

[0155] <Various chemicals> NR:TSR20 BR: UBEPOL-BR360B (high cis BR, vinyl content: 1.9 mol%, cis content: 98 mol%, Mw: 570,000) manufactured by UBE Corporation Copolymer 1: A copolymer prepared in Preparation Example 1 described below (ethylene-farnesene copolymer, ethylene unit content: 70 mol%) Copolymer 2: A copolymer produced in Production Example 2 described below (ethylene-myrcene copolymer, 60 mol% ethylene units) Copolymer 3: A copolymer produced in Production Example 3 described below (ethylene-farnesene copolymer, ethylene unit content: 40 mol%) Carbon black: Diablack I (N220) (N2SA: 114m) manufactured by Mitsubishi Chemical Corporation 2 / g, average primary particle diameter: 22nm) Oil: H&R VivaTec 500 (TDAE oil) Antioxidant 1: Antigen 6C (6PPD, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Sumitomo Chemical Co., Ltd. Antioxidant 2: Nocrac 224 (TMQ, 2,2,4-trimethyl-1,2-dihydroquinoline polymer) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Wax: Ozoace 0355 (paraffin wax) manufactured by Nippon Seiro Co., Ltd. Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Stearic acid: Camellia stearic acid beads manufactured by NOF Corporation Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. Vulcanization accelerator: Noccela CZ (N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0156] Production Example 1: Production of Copolymer 1 A cocatalyst, butyloctyl magnesium, and metallocene are added to a reactor containing methylcyclohexane and stirred to allow alkylation. The catalyst concentration is adjusted to match the target molecular weight, Tg, etc. of copolymer 1. Ethylene and farnesene are then added continuously in a 70:30 molar ratio to carry out the polymerization reaction, which is then terminated by cooling, degassing, and adding ethanol. An antioxidant is added to the polymer solution produced by the polymerization reaction, and the solution is dried in a vacuum oven to obtain copolymer 1.

[0157] Production Example 2: Production of Copolymer 2 Copolymer 2 is obtained in the same manner as in Production Example 1, except that the molar ratio of ethylene to myrcene is 60:40.

[0158] Production Example 3: Production of Copolymer 3 Copolymer 3 is obtained in the same manner as in Production Example 1, except that the molar ratio of ethylene to farnesene is 40:60.

[0159] Examples and Comparative Examples According to the formulation shown in Table 1, a 1.7 L closed-type Banbury mixer was used to knead all chemicals except sulfur and vulcanization accelerators at a discharge temperature of 160°C for 4 minutes to obtain a kneaded mixture. Next, using an open roll, sulfur and vulcanization accelerators were added to the kneaded mixture, and the mixture was kneaded for 4 minutes until the temperature reached 105°C to obtain an unvulcanized rubber composition. The unvulcanized rubber composition obtained was molded to fit the shape of the sidewall, and then bonded together with other tire components to produce an unvulcanized tire. The tire was then vulcanized at 170°C to obtain each test tire.

[0160] <Low fuel consumption performance> The rolling resistance of each test tire was measured using a rolling resistance tester, and the reciprocal of the rolling resistance was expressed as an index, with the tire of Comparative Example 1 being set at 100. The larger the value, the smaller the rolling resistance and the more excellent the fuel economy performance.

[0161] <Ozone resistance> Ozone cracks on the sidewalls were measured when each test tire was run using an ozone drum tester, and a value was calculated by adding 0.1 to the total number of cracks 0.1 mm or longer, and the reciprocal of this value was expressed as an index, with the tire of Comparative Example 1 set at 100. A larger value indicates smaller cracks and better ozone resistance.

[0162] The sum of the fuel economy performance index and the ozone resistance performance index is the overall performance index.

[0163] [Table 1]

[0164] <Embodiment> Examples of embodiments of the present invention are given below. [1] A tire with a sidewall, the sidewall is made of a rubber composition containing a rubber component, the rubber component includes an isoprene-based rubber and a branched conjugated diene copolymer; The branched conjugated diene copolymer has a structural unit derived from an ethylene unit and a 1,3-diene compound represented by CH2=CR-CH=CH2 (wherein R represents a hydrocarbon group having 3 or more carbon atoms), The ethylene unit content in the branched conjugated diene copolymer is M (mol%), The thickness of the surface rubber layer at the maximum tire width position is T (mm). The content of the branched conjugated diene copolymer in the rubber component is C SW (mass%), M is 50 or more, M×C SW / T 3 Tires with a rating of over 70. [2] The tire according to [1] above, wherein the 1,3-diene compound is farnesene and / or myrcene. [3] The tire according to [1] or [2] above, wherein the rubber component further contains butadiene rubber. [4] The above M × C SW / T 3 The tire according to any one of the above [1] to [3], wherein the value is greater than 300. [5] The tire according to any one of the above [1] to [4], wherein T is greater than 1.0 mm and less than 2.5 mm. [6] The rubber composition contains carbon black, and the N2SA of the carbon black contained in the rubber composition is 100m 2 / g or more 140m 2 The tire according to any one of the above [1] to [5], wherein the tensile strength is 1 / g or less. [7] The tire according to any one of the above [1] to [6], wherein the rubber composition contains carbon black, and the average primary particle diameter of the carbon black contained in the rubber composition is 15 nm or more and 25 nm or less. [Explanation of symbols]

[0165] 1 Tread section 2 Belt 3 bands 21 Bead core 22 Bead Apex 31 Sidewall 32 Inner liner 33 Carcass CL Tire Equator T Thickness of the surface rubber layer at the maximum tire width PW Maximum tire width position

Claims

1. A tire having a sidewall, the sidewall is made of a rubber composition containing a rubber component, the rubber component includes an isoprene-based rubber and a branched conjugated diene copolymer; The branched conjugated diene copolymer comprises an ethylene unit and a CH 2 =CR-CH=CH 2 (wherein R represents a hydrocarbon group having 3 or more carbon atoms), The ethylene unit content in the branched conjugated diene copolymer is M (mol%), The thickness of the surface rubber layer at the maximum tire width position is T (mm), The content of the branched conjugated diene copolymer in the rubber component is C SW (mass%), M is 50 or more, MxC SW / T 3 Tires with a rating of over 70.

2. 2. The tire of claim 1, wherein the 1,3-diene compound is farnesene and / or myrcene.

3. The tire according to claim 1 or 2, wherein the rubber component further contains a butadiene rubber.

4. The M×C SW / T 3 3. The tire of claim 1 or 2, wherein:

5. 3. The tire according to claim 1 or 2, wherein T is greater than 1.0 mm and less than 2.5 mm.

6. The rubber composition contains carbon black, and N of the carbon black contained in the rubber composition 2 SA is 100m 2 / g or more 140m 2 The tire according to claim 1 or 2, wherein the tensile strength is 1 / g or less.

7. The tire according to claim 1 or 2, wherein the rubber composition contains carbon black, and the carbon black contained in the rubber composition has an average primary particle diameter of 15 nm or more and 25 nm or less.

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