Rubber composition and tire

Abstract

To provide a novel rubber composition exhibiting an excellent grip performance, and a tire equipped with a tire member including the rubber composition.SOLUTION: A rubber composition includes a rubber constituent including epoxidized diene rubber, at least one selected from a group including an imidazole compound and a divalent or more carboxylic acid compound, and an oil. In the rubber composition, a value (AO / T1) is 0.045 or more, obtained by dividing a content (pts.mass) AO based on 100 pts.mass of the rubber constituent of the oil, by a longest relaxation time (time) T1 obtained by a Procedure X of the rubber composition.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a rubber composition and a tire.

Background Art

[0002] In a tire mounted on an automobile, it is important to maintain the grip force between the tread and the road surface during any of driving, braking, and turning of the automobile. Conventionally, various methods for improving grip performance have been studied. For example, Patent Document 1 describes a pneumatic tire provided with a tread rubber having improved grip performance by using fine particle zinc oxide.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a novel rubber composition exhibiting excellent grip performance and a tire provided with a tire member made of the rubber composition.

Means for Solving the Problems

[0005] The present invention relates to the following rubber composition. A rubber composition comprising a rubber component containing an epoxidized diene rubber, at least one selected from the group consisting of an imidazole compound and a carboxylic acid compound having a valence of 2 or more, and an oil, wherein a content (parts by mass) A of the oil with respect to 100 parts by mass of the rubber component O is divided by a longest relaxation time (hours) T1 obtained from Procedure X of the rubber composition, and a value (A O / T1) is 0.045 or more.

Effects of the Invention

[0006] According to the present invention, it is possible to provide a novel rubber composition exhibiting excellent grip performance and a tire provided with a tire member made of the rubber composition.

Brief Description of the Drawings

[0007]

Figure 1

Mode for Carrying Out the Invention

[0008] A rubber composition according to an embodiment of the present invention is a rubber composition containing a rubber component containing an epoxidized diene rubber, at least one selected from the group consisting of an imidazole compound and a polyvalent carboxylic acid compound, and an oil, The content (parts by mass) A of the oil with respect to 100 parts by mass of the rubber component O divided by the longest relaxation time (hours) T1 obtained from Procedure X of the rubber composition (A O / T1) is 0.045 or more, which is a rubber composition.

[0009] Although not intended to be bound by theory, the reason why the rubber composition exhibits excellent grip performance is considered as follows. That is, it contains an epoxidized diene rubber, at least one selected from the group consisting of an imidazole compound and a polyvalent carboxylic acid compound, and an oil, and the value obtained by dividing the oil amount by the longest relaxation time (A O / T1) is a certain value or more, which is considered to improve all of flexibility, the magnitude of hysteresis loss, and the response speed to hysteresis loss, contributing to the improvement of grip performance.

[0010] A O / T1 is preferably 0.100 or more.

[0011] A OIt is considered that the grip performance is improved by satisfying the value of / T1 under more severe conditions.

[0012] The rubber component preferably contains isoprene rubber in an amount of more than 0% by mass and less than 50% by mass.

[0013] This is because the effects of the invention can be further enhanced.

[0014] The epoxidation rate of the epoxidized diene rubber is preferably 50 mol% or less.

[0015] This is because the effects of the invention can be further enhanced.

[0016] The content of the filler is preferably less than 45 parts by mass with respect to 100 parts by mass of the rubber component.

[0017] This is because the effects of the invention can be further enhanced.

[0018] Another embodiment of the present invention is a tire having a tire member composed of any of the above rubber compositions.

[0019] This is because it is one of the preferred forms in which the characteristics of the above rubber composition can be exhibited.

[0020] When the thickness (mm) of the tire member is W, A O / T1 and W and the product (A O ×W / T1) is preferably 0.180 or more.

[0021] This is because the effects of the invention can be further enhanced.

[0022] The tire member is preferably a cap tread.

[0023] This is because it is one of the preferred forms in which the characteristics of the above rubber composition can be exhibited.

[0024] <Definition> The "normal state" refers to a no-load state in which the tire is mounted on a normal rim and filled with air at normal internal pressure.

[0025] The "dimensions of each part of the tire" are, unless otherwise specified, values specified in the normal state for those that appear on the outer surface of the tire. On the other hand, those existing inside the tire or on the tire cut surface are values specified in a state where, for example, the tire is cut by a plane including the tire rotation axis and the cut tire piece is held at the rim width of the normal rim.

[0026] The "normal rim" is the rim defined for each tire in a standard system including the standards on which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Association), it refers to the standard rim in the applicable sizes described in the "JATMA YEAR BOOK"; in the case of ETRTO (The European Tyre and Rim Technical Organisation), it refers to the "Measuring Rim" described in the "STANDARDS MANUAL"; in the case of TRA (The Tire and Rim Association, Inc.), it refers to the "Design Rim" described in the "YEAR BOOK". Refer to JATMA, ETRTO, and TRA in that order, and follow the relevant standard if there is an applicable size at the time of reference. For tires not defined in the standards, it refers to the rim that can be mounted on the tire and can hold the internal pressure, that is, among the rims that do not cause air leakage between the rim / tire, the one with the smallest rim diameter and then the narrowest rim width.

[0027] "Normal internal pressure" refers to the air pressure specified for each tire in the standard system including the standards on which the tire is based. For example, in the case of JATMA, it is the "maximum air pressure"; in the case of ETRTO, it is "INFLATION PRESSURE"; and in the case of TRA, it refers to the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". Refer to JATMA, ETRTO, and TRA in this order, similar to the case of the normal rim, and follow the relevant standard if there is an applicable size during the reference. In the case of a tire not specified in the standard, it refers to the normal internal pressure (however, not less than 250 kPa) of another tire size described with the said normal rim as the standard rim (however, those specified in the standard). If there are multiple normal internal pressures not less than 250 kPa described, the minimum value among them shall be referred to.

[0028] "Normal load" refers to the load specified for each tire in the standard system including the standards on which the tire is based. For example, in the case of JATMA, it is the "maximum load capacity"; in the case of ETRTO, it is "LOAD CAPACITY"; and in the case of TRA, it is the maximum value described in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES". Refer to JATMA, ETRTO, and TRA in this order, similar to the case of the normal rim and normal internal pressure, and follow the relevant standard if there is an applicable size during the reference. In the case of a tire not specified in the standard, the maximum load capacity W L calculated separately shall be taken as the normal load.

[0029] "Maximum load capacity (W L )" is calculated by the following formula. "V" is the virtual volume of the tire (mm 3) "Dt" is the outer diameter of the tire (mm) in the normal state, "Ht" is the cross-sectional height of the tire in the cross-section of the tire by the plane including the tire rotation axis (mm) in the tire radial direction, and "Wt" is the cross-sectional width of the tire (mm) in the normal state. When the rim diameter of the tire is R, Ht can be obtained by (Dt - R) / 2. Wt is the value obtained excluding patterns, characters, etc. on the tire sidewall. Note that the maximum load capacity is synonymous with the normal load.

[0030]

Number

[0031] The "tire member" includes, for example, cap tread, base tread, sidewall, clinch, etc., but is not limited thereto.

[0032] The "thickness (W) of the tire member" is the thickness (mm) measured in a state where the tire cut by the plane passing through the tire rotation axis is held at the normal rim width. More specifically, the thickness of the cap tread and the base tread is the thickness in the tire radial direction on the tire center line. When there is a groove on the tire center line, it is the thickness of the rubber layer at the center in the tire width direction of the land portion closest to the tire center line. The thickness of the sidewall is the thickness of the sidewall rubber at the maximum width position of the tire. The thickness of the clinch is the thickness of the rubber layer measured along the normal line of the carcass body portion passing through the contact point Pc where the sidewall and the clinch contact on the outer surface of the tire.

[0033] The "plasticizer" is a material that imparts plasticity to the rubber component and is a component extracted from the rubber composition using acetone. Also, the plasticizer includes a plasticizer that is liquid (liquid state) at 25°C and a plasticizer that is solid at 25°C. However, waxes and stearic acid commonly used in the tire industry are not included. The content of the plasticizer also includes the amount of the plasticizer in the rubber component stretched by the plasticizer.

[0034] <Measurement method> "Procedure X" is a method for determining the longest relaxation time (in seconds) T1 of a rubber composition (Masayuki Takahashi, "Practical Rheology for Beginners, Part 3: Dynamic Viscoelasticity of Polymers", Journal of the Society of Rheology, Japan, 2021, 49, 135-146). Referring to pages 140, left column to right column of the same reference (Takahashi), the shear modulus G(t), which is a function of time t when a certain small shear strain is applied, is G(t)=G1exp(-t / T1)+G2exp(-t / T2)+··· (where T1 represents the longest relaxation time.) Although it is expressed as such, since this exponential function decreases relatively quickly, for t > T1, only the contribution of the term with the longest relaxation time remains. Therefore, G(t)=G1exp(-t / T1) After approximating and taking the logarithm of both sides, lnG(t)=lnG1-t / T1 Furthermore, logG(t)=logG1-t / (2.303T1) It can be transformed. Therefore, the longest relaxation time (in seconds) T1 can be obtained from the slope of a semi-logarithmic plot of lnG(t) against t, or a semi-logarithmic plot of logG(t) against t. This method is called Procedure X.

[0035] The "longest relaxation time" is measured as follows. That is, for the rubber composition, a measurement sample with a height of 16 mm, a width of 40 mm, and a thickness of about 2 mm is prepared. As the measuring device, a dynamic viscoelasticity measuring device DMA + 300 for high frequencies manufactured by Metrabiv is used. The measurement sample is fixed with a film shear type jig (the gap between the jigs is 2 mm), held at the measurement temperature (60 °C) for 5 minutes, then a 10% shear strain is applied and held, and the time change of the shear modulus G(t) is measured every 5 seconds for 20 minutes. From this measurement result, the longest relaxation time (time) T1 is obtained by Procedure X. That is, all the points of lnG(t) from 1000 seconds to 1200 seconds are plotted on a semi-logarithmic scale against time t, approximated to a straight line by the least squares method, and the longest relaxation time (time) T1 is obtained from the slope (-(1 / T1)). Note that the above shear modulus is synonymous with the relaxation modulus in the above-mentioned literature (Takahashi).

[0036] The "epoxidation rate" for an epoxidized diene rubber is the ratio (mol%) of the number of epoxidized double bonds to the total number of double bonds in the rubber before epoxidation, and is measured using an NMR apparatus of the JNM-ECA series manufactured by JEOL Ltd. Note that double bonds disappear due to epoxidation.

[0037] The "glass transition temperature (Tg) of the rubber composition" is the temperature (tanδ peak temperature) corresponding to the maximum value within the range of -60 °C or higher and 40 °C or lower of the temperature distribution curve of tanδ, measured using a dynamic viscoelasticity measuring device (for example, the Implex series manufactured by GABO) under the conditions of a frequency of 10 Hz, an initial strain of 10%, a dynamic strain of ±0.5%, and a temperature increase rate of 2 °C / min. Note that in the measurement within the range of -60 to 40 °C, when the tanδ value continuously increases or decreases with the temperature increase, the glass transition temperature of the rubber composition is 40 °C or -60 °C, respectively. Also, when there are two or more points showing a maximum value within the range of -60 °C or higher and 40 °C or lower, the point with the lowest temperature is taken as the glass transition temperature.

[0038] "N2SA of silica" is measured by the BET method in accordance with ASTM D3037-93.

[0039] "N2SA of carbon black" is measured in accordance with JIS K 6217-2:2017.

[0040] "Average primary particle diameter" can be determined by observing with a transmission or scanning electron microscope, measuring 400 or more primary particles observed in the field of view, and taking the average. When the shape of the particle is approximately circular, the diameter of the circle is taken as the particle diameter; when it is needle-shaped or rod-shaped, the minor axis is taken as the particle diameter; in other cases, the equivalent circle diameter is calculated from the electron microscope image and taken as the particle diameter. The equivalent circle diameter is obtained as "the positive square root of 4×(area of the particle) / π". It is applicable to carbon black, silica, etc.

[0041] <Rubber composition> The rubber composition of this embodiment contains a rubber component containing an epoxidized diene rubber, at least one selected from the group consisting of an imidazole compound and a carboxylic acid compound having a valence of 2 or more, and an oil.

[0042] [Rubber component] The epoxidized diene rubber is not particularly limited. For example, epoxidized natural rubber (ENR), epoxidized isoprene-based rubbers such as epoxidized isoprene rubber, epoxidized butadiene rubber, epoxidized butadiene acrylonitrile rubber, epoxidized styrene-butadiene rubber, epoxidized isoprene-butadiene rubber, etc. can be mentioned. The epoxidized diene rubber may be used alone or in combination of two or more.

[0043] The epoxidized diene rubber is not particularly limited, and it may be a commercially available one or one obtained by epoxidizing a diene rubber. The epoxidation of the diene rubber can be carried out in accordance with the epoxidation of natural rubber.

[0044] Examples of methods for epoxidizing natural rubber include, for example, the chlorohydrin method, the direct oxidation method, the hydrogen peroxide method, the alkyl hydroperoxide method, the peracid method, etc. (Japanese Patent Publication No. 4-26617, Japanese Unexamined Patent Application Publication No. 2-110182, British Patent No. 2113692, etc.). Examples of the peracid method include methods of reacting natural rubber with organic peracids such as peracetic acid and performic acid. Note that by adjusting the amount of the organic peracid and the reaction time, epoxidized natural rubbers with various epoxidation rates can be prepared. The natural rubber to be epoxidized is not particularly limited, and for example, those commonly used in the tire industry such as SIR20, RSS#3, TSR20, deproteinized natural rubber (DPNR), high-purity natural rubber (HPNR), etc. can be used.

[0045] From the perspective of practical aspects such as easy availability, ENR, epoxidized butadiene rubber, etc. are preferred as the epoxidized diene rubber, and ENR is more preferred.

[0046] The epoxidation rate of the epoxidized diene rubber is preferably more than 15 mol%, more preferably more than 20 mol%, still more preferably 25 mol% or more. On the other hand, from the perspective of fracture properties, the epoxidation rate is preferably 75 mol% or less, more preferably less than 60 mol%, still more preferably 50 mol% or less, still more preferably less than 50 mol%, still more preferably less than 30 mol%, still more preferably 25 mol% or less. The epoxidation rate is the value measured by the above method.

[0047] The content of the epoxidized diene rubber in 100% by mass of the rubber component is preferably more than 50% by mass, more preferably 60% by mass or more. The content may be more than 70% by mass, may be 80% by mass or more, may be more than 90% by mass, may be more than 95% by mass, or may be 100% by mass.

[0048] The rubber component may contain other rubber components other than the epoxidized diene rubber described above. As the other rubber components, crosslinkable rubber components generally used in the tire industry can be used. For example, natural rubber (NR), isoprene rubber (IR), isoprene-based rubber (IR-based rubber) including IR, styrene-butadiene rubber (SBR), butadiene rubber (BR), styrene-isoprene-butadiene copolymer rubber (SIBR), unepoxidized diene rubbers such as chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), polynorbornene rubber, etc., and non-diene rubbers such as butyl rubber (IIR), hydrogenated nitrile rubber (HNBR), ethylene-propylene rubber, silicone rubber, chlorinated polyethylene rubber, fluororubber (FKM), acrylic rubber (ACM), hydrin rubber, etc. Among these, IR-based rubber is preferred, and especially NR is preferred. The other rubber components may be used alone or in combination of two or more.

[0049] The content of the IR-based rubber is preferably less than 50% by mass and may be 0% by mass. The content is more preferably less than 45% by mass, still more preferably 40% by mass or less. When the rubber component contains IR-based rubber, the content is more than 0% by mass, preferably more than 5% by mass, more preferably more than 10% by mass, still more preferably more than 15% by mass, and still more preferably 20% by mass or more.

[0050] [Dicarboxylic acid compound with a valence of 2 or more] A carboxylic acid compound having a valency of 2 or more is a compound having two or more carboxyl groups. The carboxylic acid compound having a valency of 2 or more is not particularly limited as long as it can react with the epoxy group of the epoxidized diene rubber to form an ionic bond, and various compounds can be used. The carboxylic acid compound having a valency of 2 or more may be any of an aliphatic carboxylic acid compound, an alicyclic carboxylic acid compound, and an aromatic carboxylic acid compound. Further, the carboxylic acid compound having a valency of 2 or more may have a substituent. Examples of the substituent of the carboxylic acid compound having a valency of 2 or more include a hydroxy group, an alkoxy group, an amino group, etc. The number of these substituents may be 1 or may be 2 or more. Also, the type of substituent may be 1 type or may be 2 types or more.

[0051] Examples of the carboxylic acid compound having a valency of 2 or more include divalent carboxylic acid compounds such as maleic acid, fumaric acid, phthalic acid, malic acid, tartaric acid, suberic acid, dodecanedioic acid, etc., trivalent carboxylic acid compounds such as citric acid, etc., tetravalent carboxylic acid compounds such as pyromellitic acid, etc., hexavalent carboxylic acid compounds such as mellitic acid, etc. Among these, divalent carboxylic acid compounds such as suberic acid and dodecanedioic acid are preferable.

[0052] The carboxylic acid compound having a valency of 2 or more may be used alone or in combination of two or more.

[0053] Preferable examples of the carboxylic acid compound having a valency of 2 or more include divalent carboxylic acid compounds. As the divalent carboxylic acid compound, the compound represented by the following formula (I) can be preferably used. Since carboxyl groups are present at both ends of this compound, it is possible to form a strong network between polymers. HOOC-A-COOH (I) (In the formula, A is a divalent hydrocarbon group having 1 to 18 carbon atoms and may have a substituent.)

[0054] The hydrocarbon group of A may be any of aliphatic, alicyclic, and aromatic. Among the hydrocarbon groups of A, the aliphatic hydrocarbon group and the alicyclic hydrocarbon group may be either saturated or unsaturated. Among the hydrocarbon groups of A, the alicyclic hydrocarbon group and the aromatic hydrocarbon group refer to those in which the carbon atoms constituting the ring are unsubstituted, and the carbon atoms may be substituted with an alkyl group. Among the hydrocarbon groups of A, the aliphatic hydrocarbon group may be either linear or branched. The number of carbon atoms in the hydrocarbon group of A is preferably 2 or more, and preferably 12 or less, more preferably 10 or less, still more preferably 8 or less, and even more preferably 6 or less.

[0055] Specific examples of the hydrocarbon group of A include, for example, an alkylene group, an alkenylene group, a cycloalkylene group, an arylene group, etc., and an alkylene group is preferred. As the alkylene group, linear alkylene groups such as a methylene group, an ethylene group, an n-propylene group, an n-butylene group, an n-hexylene group (hexamethylene group), an n-decylene (decamethylene group), and branched alkylene groups such as an isopropylene group, an isobutylene group, and a 2-methylpropylene group can be mentioned. Among these, a linear alkylene group is preferred, an ethylene group, an n-propylene group, an n-hexylene group (hexamethylene group), and an n-decylene (decamethylene group) are more preferred, and an n-hexylene group (hexamethylene group) and an n-decylene (decamethylene group) are even more preferred.

[0056] The hydrocarbon group of A may have a substituent. Examples of the substituent include a hydroxy group, an alkoxy group, an amino group, a dialkylamino, etc. The number of these substituents may be 1 or may be 2 or more. Also, the types of these substituents may be 1 type or may be 2 types or more.

[0057] Regarding the hydrocarbon group of A, as the alkyl group, alkoxy group, etc., those having 1 to 6 carbon atoms are preferred, more preferably 1 to 4 carbon atoms, and still more preferably 1 or 2 carbon atoms.

[0058] From the perspective of the effects of the present invention, the content of the carboxylic acid compound having a valency of 2 or more is preferably more than 0.50 parts by mass, more preferably more than 0.60 parts by mass, still more preferably more than 0.70 parts by mass, still more preferably more than 0.80 parts by mass, and still more preferably more than 0.90 parts by mass, based on 100 parts by mass of the epoxidized diene rubber. Further, the content is preferably less than 30 parts by mass, more preferably less than 25 parts by mass, and still more preferably 20 parts by mass or less.

[0059] [Imidazole compound] The imidazole compound is a compound having an imidazole ring. The imidazole compound is not particularly limited as long as it can react with the epoxy group of the epoxidized diene rubber to form an ionic bond.

[0060] Various imidazole compounds can be used. For example, the compound represented by the following formula (II) is preferable.

[0061] [Chemical formula] (In the formula, R 1 , R 2 , R 3 , R 4 represent the same or different hydrogen atoms or hydrocarbon groups. R 3 , R 4 may be bonded to each other to form a ring structure.)

[0062] R 1 , R 2 , R 3 , R 4 Examples of the hydrocarbon group of include an alkyl group having 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms; a cycloalkyl group having 5 to 24 carbon atoms, preferably 5 to 12 carbon atoms, more preferably 5 to 8 carbon atoms; an aryl group having 6 to 30 carbon atoms, preferably 6 to 24 carbon atoms, more preferably 6 to 12 carbon atoms; and an aralkyl group having 7 to 25 carbon atoms, preferably 7 to 13 carbon atoms, more preferably 7 to 10 carbon atoms.

[0063] Also, when R 3 and R 4 combine to form a ring structure, examples of the ring structure formed by R 3 and R 4 with the carbon atom of the imidazole ring include, for example, an aromatic ring having 5 to 12 carbon atoms, a heterocyclic ring, an aliphatic ring, etc., and preferably a benzene ring.

[0064] From the viewpoint of the effects of the present invention, it is preferable that at least one of R 1 , R 2 , R 3 , R 4 is an alkyl group, and it is more preferable that two of R 1 , R 2 , R 3 , R 4 are alkyl groups and the other two are hydrogen atoms, and it is even more preferable that R 1 and R 2 are alkyl groups and R 3 and R 4 are hydrogen atoms.

[0065] Specific examples of the imidazole compound include imidazole, 1-methylimidazole, 1-butylimidazole, 1-propylimidazole, 1-ethylimidazole, 1,2-dimethylimidazole, 1-decyl-2-methylimidazole, 1-benzyl-2-methylimidazole, benzimidazole, N-methylbenzimidazole, etc. The imidazole compound may be used alone or in combination of two or more.

[0066] Among them, imidazole, 1,2-dimethylimidazole, 1-methylimidazole, 1-benzyl-2-methylimidazole are preferable, and especially imidazole, 1,2-dimethylimidazole are preferable.

[0067] The imidazole compound may be used alone or in combination of two or more.

[0068] As the imidazole compound, for example, products of Shikoku Kasei Kogyo Co., Ltd. can be used.

[0069] From the viewpoint of the effects of the present invention, the content of the imidazole compound is preferably more than 0.50 parts by mass, more preferably more than 0.60 parts by mass, still more preferably more than 0.70 parts by mass, still more preferably more than 0.80 parts by mass, and still more preferably more than 0.85 parts by mass, based on 100 parts by mass of the epoxidized diene rubber. Further, the content is preferably less than 30 parts by mass, more preferably less than 25 parts by mass, and still more preferably 20 parts by mass or less.

[0070] [Oil] Examples of the oil include process oil, vegetable oil, animal oil, etc. Examples of the process oil include paraffinic process oil (mineral oil), naphthenic process oil, aromatic process oil, etc. Specific examples of the process oil include, for example, MES (Mild Extract Solvated), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), RAE (Residual Aromatic Extract), etc. Also, a process oil with a low content of polycyclic aromatic (PCA) compounds can be used for environmental measures. Examples of the low-PCA-content process oil include MES, TDAE, heavy naphthenic oil, etc. Further, from the viewpoint of life cycle assessment, waste oil used in a rubber mixer or an engine, or refined waste cooking oil used in a cooking shop may be used. The oil may be used alone or in combination of two or more.

[0071] Vegetable oils include, 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 oil, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grape seed oil, wood wax, etc. Further, as vegetable oils, there are also 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, oxidatively polymerized oils obtained by oxidizing the above oils, waste cooking oils recovered from those used as edible oils, etc. Note that vegetable oils may be liquid or solid at normal temperature (25°C).

[0072] Vegetable oils preferably contain acylglycerol, and more preferably contain triacylglycerol. In this specification, acylglycerol refers to a compound in which the hydroxy group of glycerin and a fatty acid are ester-bonded. Acylglycerol is not particularly limited, and may be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Further, acylglycerol may be a monomer, a dimer, or a multimer of three or more units. Note that acylglycerols of two or more units can be obtained by thermal polymerization, oxidative polymerization, etc. Also, acylglycerol may be liquid or solid at normal temperature (25°C).

[0073] The method for confirming whether the above acylglycerol is contained in the rubber composition is not particularly limited, but 1 it can be confirmed by 1H-NMR measurement. For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at normal temperature (25°C) for 24 hours. After removing the rubber composition, at room temperature 1When measuring 1H-NMR and setting the signal of tetramethylsilane (TMS) to 0.00 ppm, signals around 5.26 ppm, around 4.28 ppm, and around 4.15 ppm were observed, and these signals are presumed to be signals derived from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group. In this paragraph, "around" means a range of ±0.10 ppm.

[0074] The fatty acid is not particularly limited and may be 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.

[0075] Among them, it is desirable that the fatty acid contains a fatty acid with few double bonds, that is, a saturated fatty acid or a monounsaturated fatty acid, and oleic acid is preferred. As the vegetable oil containing such a fatty acid, for example, a vegetable oil containing a saturated fatty acid or a monounsaturated fatty acid may be used, or a vegetable oil subjected to modification such as transesterification may be used. In addition, in order to produce a vegetable oil containing such a fatty acid, plants may be improved by variety improvement, genetic recombination, genome editing, etc.

[0076] As the vegetable oil, for example, those commercially available from Idemitsu Kosan Co., Ltd., Sankyo Oil Chemical Co., Ltd., ENEOS Co., Ltd., Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Fuji Kogyo Co., Ltd., Nisshin Oillio Group Co., Ltd., etc. can be used.

[0077] Examples of animal oils include fish oil, beef tallow, whale oil, or oleyl alcohol derived therefrom.

[0078] When contained, the content relative to 100 parts by mass of the rubber component is preferably more than 5 parts by mass, more preferably more than 10 parts by mass, and still more preferably 15 parts by mass or more. Also, the content is preferably less than 50 parts by mass, more preferably less than 40 parts by mass, and still more preferably less than 30 parts by mass. The content of the oil includes the amount of extender oil and the like used for the extension of the rubber component.

[0079] [Other components] In the rubber composition, as components other than the above, various compounding agents and additives common in the tire industry, such as fillers such as carbon black and silica, silane coupling agents, plasticizers other than oil, anti-aging agents, waxes, stearic acid, zinc oxide, vulcanizing agents, and vulcanization accelerators, can be compounded. However, the rubber composition of this embodiment does not necessarily require fillers or silane coupling agents and may not contain them. Also, the rubber composition of this embodiment does not necessarily require vulcanization chemicals such as vulcanizing agents and vulcanization accelerators and may not contain them.

[0080] (Filler) The rubber composition may contain a filler, but the content of the filler is preferably less than 45 parts by mass, more preferably less than 20 parts by mass, still more preferably less than 5 parts by mass, relative to 100 parts by mass of the rubber component, or the filler may not be contained. The content of the filler is the total content of the fillers, and when only one type of filler is contained, it is the content of the one type of filler.

[0081] As the filler, silica or carbon black can be used, and fillers usually used in the tire industry, such as aluminum hydroxide, alumina (aluminum oxide), calcium carbonate, magnesium sulfate, talc, clay, etc. can also be used. Silica and carbon black are representative as the filler. The filler may be used alone or in combination of two or more.

[0082] ≪Silica≫ The silica is not particularly limited, and for example, silica prepared by a dry method (anhydrous silica), silica prepared by a wet method (hydrous silica), etc., which are common in the tire industry, can be used. Among them, hydrous silica prepared by a wet method is preferred because of its large number of silanol groups. The silica may be used alone or in combination of two or more.

[0083] From the viewpoints of low fuel consumption performance and wear resistance performance, the nitrogen adsorption specific surface area (N2SA) of the silica is preferably more than 140 m 2 / g, more preferably more than 150 m 2 / g, still more preferably 160 m 2 / g or more, and particularly preferably 175 m 2 / g or more. Also, from the viewpoints of low fuel consumption performance and processability, it is preferably less than 350 m 2 / g, more preferably less than 300 m 2 / g, still more preferably less than 250 m 2 / g. The N2SA of the silica is measured by the above-mentioned measurement method.

[0084] The average primary particle diameter of the silica is preferably less than 25 nm, more preferably less than 22 nm, and still more preferably less than 20 nm. The lower limit of the average primary particle diameter is not particularly limited, but is preferably more than 1 nm, more preferably more than 3 nm, and still more preferably more than 5 nm. The average primary particle diameter can be determined by the above-mentioned method.

[0085] <<Carbon Black>> The carbon black is not particularly limited, and those commonly used in the tire industry such as GPF, FEF, HAF, ISAF, SAF, etc. can be used. Specifically, N110, N115, N120, N125, N134, N135, N219, N220, N231, N234, N293, N299, N326, N330, N339, N343, N347, N351, N356, N358, N375, N539, N550, N582, N630, N642, N650, N660, N683, N754, N762, N765, N772, N774, N787, N907, N908, N990, N991, etc. can be preferably used. In addition, self-made synthetic products, etc. can also be preferably used. The carbon black can be used alone or in combination of two or more kinds.

[0086] From the viewpoint of reinforcement, the nitrogen adsorption specific surface area (N2SA) of the carbon black is preferably 10 m 2 / g or more, more preferably 20 m 2 / g or more, still more preferably 35 m 2 / g or more, particularly preferably 50 m 2 / g or more. Further, from the viewpoints of low fuel consumption performance and processability, it is preferably 200 m 2 / g or less, more preferably 150 m 2 / g or less, still more preferably 130 m 2 / g or less. The N2SA of the carbon black is measured by the above-mentioned measurement method.

[0087] The average primary particle diameter of the carbon black is preferably less than 30 nm, more preferably less than 26 nm, still more preferably less than 23 nm, and even more preferably 22 nm or less. The lower limit of the average primary particle diameter is not particularly limited, but is preferably more than 1 nm, more preferably more than 3 nm, and still more preferably more than 5 nm. The average primary particle diameter can be determined by the above-mentioned method.

[0088] (Silane coupling agent) Silica is preferably used in combination with a silane coupling agent. The silane coupling agent is not particularly limited, and in the tire industry, any silane coupling agent conventionally used in combination with silica can be used. For example, mercapto-based silane coupling agents such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane; 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; vinyl-based silane coupling agents such as vinyltriethoxysilane, vinyltrimethoxysilane; amino-based silane coupling agents such as 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltriethoxysilane; glycidoxy-based silane coupling agents such as γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane, 3-nitropropyltriethoxysilane; chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, etc. Among them, it is preferable to contain a sulfide-based silane coupling agent and / or a mercapto-based silane coupling agent. As the silane coupling agent, for example, those commercially available from Momentive Co., Ltd. can be used. The silane coupling agent may be used alone or in combination of two or more.

[0089] The content of the silane coupling agent is preferably more than 1.0 part by mass, more preferably more than 3.0 parts by mass, and even more preferably more than 5.0 parts by mass with respect to 100 parts by mass of silica from the viewpoint of enhancing the dispersibility of silica. Also, from the viewpoints of cost and processability, it is preferably less than 30 parts by mass, more preferably less than 20 parts by mass, and even more preferably less than 15 parts by mass.

[0090] (Plasticizer) Examples of plasticizers other than oil include liquid polymers, resins, ester-based plasticizers, etc. These plasticizers may be derived from petroleum, including the above-mentioned oil, may be derived from biomass, or may be derived from naphtha recycled from rubber products or non-rubber products. Also, low-molecular-weight hydrocarbon components obtained by pyrolyzing and extracting used tires and products containing various components may be used as plasticizers. The plasticizer may be used alone or in combination of two or more.

[0091] ≪Liquid Polymer≫ The liquid polymer is not particularly limited as long as it is in a liquid state at room temperature (25°C). Examples include liquid butadiene rubber (liquid BR), liquid styrene-butadiene rubber (liquid SBR), liquid isoprene rubber (liquid IR), liquid styrene-isoprene rubber (liquid SIR), liquid farnesene rubber, etc. The liquid polymer may be used alone or in combination of two or more.

[0092] When containing a liquid polymer, the content with respect to 100 parts by mass of the rubber component is preferably more than 5 parts by mass, more preferably more than 10 parts by mass, and even more preferably 15 parts by mass or more. Also, the content is preferably less than 50 parts by mass, more preferably less than 40 parts by mass, and even more preferably less than 30 parts by mass. The content of the liquid polymer includes the amount of the extended liquid polymer used for extending the rubber component, etc.

[0093] (Ester-based Plasticizer) Examples of ester plasticizers include dibutyl adipate (DBA), diisobutyl adipate (DIBA), dioctyl adipate (DOA), bis(2-ethylhexyl) azelate (DOZ), dibutyl sebacate (DBS), diisononyl adipate (DINA), diethyl phthalate (DEP), dioctyl phthalate (DOP), diundecyl phthalate (DUP), dibutyl phthalate (DBP), dioctyl sebacate (DOS), tributyl phosphate (TBP), trioctyl phosphate (TOP), triethyl phosphate (TEP), trimethyl phosphate (TMP), thymidine triphosphate (TTP), tricresyl phosphate (TCP), trixylenyl phosphate (TXP), and the like. The ester plasticizer may be used alone or in combination of two or more.

[0094] The content of the ester plasticizer relative to 100 parts by mass of the rubber component is preferably more than 5 parts by mass, more preferably more than 10 parts by mass, and still more preferably 15 parts by mass or more. Also, the content is preferably less than 50 parts by mass, more preferably less than 40 parts by mass, and still more preferably less than 30 parts by mass. The content of the ester plasticizer includes the amount of the extended ester plasticizer used for the extension of the rubber component and the like.

[0095] (Antioxidant) The anti-aging agent is not particularly limited, but examples include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; p-phenylenediamine-based anti-aging agents such as N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), N,N'-bis(1,4-dimethylpentyl)-p-phenylenediamine (77PD), N,N'-diphenyl-p-phenylenediamine (DPPD), N,N'-ditoly-p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline-based anti-aging agents such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based anti-aging agents such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; bis, tris, polyphenol-based anti-aging agents such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Among them, p-phenylenediamine-based anti-aging agents and quinoline-based anti-aging agents are preferred, and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and polymers of 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. As commercial products, for example, products of Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinsei Chemical Industry Co., Ltd., Flexsys Co., etc. can be used. The anti-aging agent may be used alone or in combination of two or more kinds.

[0096] When containing an anti-aging agent, from the viewpoint of the ozone crack resistance of the rubber, the content relative to 100 parts by mass of the rubber component is preferably more than 0.5 part by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 part by mass. From the viewpoints of abrasion resistance performance and wet grip performance, it 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.

[0097] (Wax) The wax is not particularly limited, and any wax commonly used in the tire industry can be preferably used. For example, petroleum waxes, mineral waxes, synthetic waxes, plant-derived waxes, etc. can be mentioned. Among them, petroleum waxes and plant-derived waxes are preferred, and petroleum waxes are more preferred. Examples of plant-derived waxes include rice wax, carnauba wax, candelilla wax, etc. Examples of petroleum waxes include paraffin wax, microcrystalline wax, and their selected special waxes, etc., and paraffin wax is preferred. Note that the wax according to this embodiment does not contain stearic acid. As the wax, for example, those commercially available from Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Paramelt Co., etc. can be used. The wax may be used alone or in combination of two or more.

[0098] When the wax is contained, the content relative to 100 parts by mass of the rubber component is preferably more than 0.5 part by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 part by mass from the viewpoint of the weather resistance of the rubber. Also, from the viewpoint of preventing the whitening of the tire due to blooming, it is preferably 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.

[0099] (Stearic acid) When stearic acid is contained, the content relative to 100 parts by mass of the rubber component is preferably more than 0.5 part by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 part by mass from the viewpoint of processability. Also, from the viewpoint of vulcanization rate, it 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.

[0100] (Zinc oxide) When zinc oxide is contained, the content relative to 100 parts by mass of the rubber component is preferably more than 0.5 part by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 part by mass from the viewpoint of processability. Also, from the viewpoint of wear resistance performance, it 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.

[0101] (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. The vulcanizing agent may be used alone or in combination of two or more.

[0102] From the viewpoint of ensuring a sufficient vulcanization reaction, the content of sulfur based on 100 parts by mass of the rubber component when sulfur is contained is preferably more than 0.5 part by mass, more preferably more than 1.0 part by mass, and even more preferably more than 1.5 parts by mass. Also, from the viewpoint of preventing deterioration, it 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. When using oil-containing sulfur as the vulcanizing agent, the content of the vulcanizing agent is the total content of pure sulfur contained in the oil-containing sulfur.

[0103] As a vulcanizing agent other than sulfur, known organic crosslinking agents can also be used. The organic crosslinking agent is not particularly limited as long as it can form a crosslinking chain other than a polysulfide bond. For example, alkylphenol sulfur chloride condensate, sodium 1,6-hexamethylene-dithiocyanate dihydrate, 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane, dicumyl peroxide, etc. can be mentioned, and 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane is preferred. These organic crosslinking agents can be those commercially available from Taoka Chemical Industry Co., Ltd., Rancess Co., Ltd., Flexsys, etc.

[0104] (Vulcanization accelerator) The vulcanization accelerator is not particularly limited. For example, it includes sulfenamide-based vulcanization accelerators, thiazole-based vulcanization accelerators, guanidine-based vulcanization accelerators, thiuram-based vulcanization accelerators, thiourea-based vulcanization accelerators, dithiocarbamate-based vulcanization accelerators, aldehyde-amine-based vulcanization accelerators, aldehyde-ammonia-based vulcanization accelerators, imidazoline-based vulcanization accelerators, xanthate-based vulcanization accelerators, caprolactam disulfide, etc. These vulcanization accelerators may be used alone or in combination of two or more. Among them, from the viewpoint of more preferably obtaining the desired effect, one or more vulcanization accelerators selected from the group consisting of sulfenamide-based vulcanization accelerators, thiazole-based vulcanization accelerators, and guanidine-based vulcanization accelerators are preferred. The vulcanization accelerator may be used alone or in combination of two or more.

[0105] Examples of the sulfenamide-based vulcanization accelerator include N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N,N-dicyclohexyl-2-benzothiazolylsulfenamide (DCBS), etc.

[0106] Examples of the thiazole-based vulcanization accelerator include 2-mercaptobenzothiazole (MBT) or its salt, di-2-benzothiazolyldisulfide (MBTS), 2-(2,4-dinitrophenyl)mercaptobenzothiazole, 2-(2,6-diethyl-4-morpholinothio)benzothiazole, etc.

[0107] Examples of the guanidine-based vulcanization accelerator include 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salt of dicatecholborate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, 1,3-di-o-cumenyl-2-propionylguanidine, etc.

[0108] Examples of thiuram vulcanization accelerators include tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N), tetramethylthiuram disulfide (TMTD), tetraethylthiuram disulfide, tetramethylthiuram monosulfide (TMTM), dipentamethylenethiuram disulfide, dipentamethylenethiuram tetrasulfide, and the like.

[0109] Examples of thiourea vulcanization accelerators include thiourea compounds such as thiocarbamide, diethylthiourea, dibutylthiourea, trimethylthiourea, and diorthotolylthiourea, and N,N'-diphenylthiourea, trimethylthiourea, N,N'-diethylthiourea, and the like.

[0110] 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), tellurium diethyldithiocarbamate (TeEDC), and the like.

[0111] When a vulcanization accelerator is contained, the content with respect to 100 parts by mass of the rubber component is preferably more than 0.5 part by mass, more preferably more than 1.0 part by mass, and still more preferably more than 1.5 parts by mass. Also, the content is preferably less than 10 parts by mass, more preferably less than 8.0 parts by mass, and still more preferably less than 5.0 parts by mass.

[0112] In this specification, various materials containing carbon atoms (such as rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from carbon dioxide in the atmosphere. As a method for obtaining a formulation of the various materials from carbon dioxide, carbon dioxide may be directly converted, or methane obtained through a methanation process of synthesizing methane from carbon dioxide may be converted.

[0113] <Physical properties of the rubber composition> [A O / T1] A O The value of A / T1 is preferably 0.050 or more, more preferably 0.090 or more, still more preferably 0.100 or more, still more preferably 0.200 or more, still more preferably 0.300 or more, still more preferably 0.500 or more, and still more preferably 1.000 or more from the viewpoint of the effects of the present invention. On the other hand, O the value of A / T1 is preferably 50 or less, more preferably 30 or less, still more preferably 10 or less, still more preferably 5 or less, and still more preferably 3 or less.

[0114] A O can be increased or decreased by increasing or decreasing the amount of oil blended in the rubber composition. On the other hand, T1 can be increased or decreased by adjusting the crosslink density by adjusting the time and temperature when heating and pressurizing the uncured rubber composition. Therefore, by these combinations, the value of A / T1 can be adjusted. O

[0115] [Tg] The glass transition temperature (Tg) of the rubber composition of this embodiment is preferably -45°C or lower. The Tg is more preferably less than -50°C, and still more preferably less than -60°C. There is no particular limitation on the lower limit of the Tg, but it is usually about -100°C.

[0116] ​The Tg can be appropriately adjusted according to the types and compounding amounts of the rubber component, filler, plasticizer, etc. For example, it can be lowered by reducing the glass transition point of the rubber component, etc., and conversely, it can be raised by increasing the glass transition point of the rubber component, etc.

[0117] <Tire> The rubber composition can be used to form a tire member composed of the rubber composition, and a tire having the tire member can be obtained. The tire member is not particularly limited, and examples thereof include a cap tread, a base tread, a sidewall, a clinch, etc. Among these, since the rubber composition exhibits excellent grip performance, it is preferably used for the cap tread.

[0118] Hereinafter, the tire of the present embodiment will be described with reference to the drawings. However, the tire of the present embodiment is not limited by the drawings.

[0119] FIG. 1 is a cross-sectional view of a tire taken along a plane passing through the tire rotation axis, showing the upper half on the right side of the tire center line CL. The tire 1 in FIG. 1 includes a tread 2 having a tread surface in contact with the ground, a sidewall 3, a wing 4 sandwiched between the tread 2 and the sidewall 3, a clinch 5 extending from one end of the sidewall to the rim, a band 6 disposed on the inner side in the tire radial direction of the tread, a breaker 7 disposed further on the inner side in the tire radial direction of the band, a carcass 8 disposed further on the inner side in the tire radial direction of the breaker, and an inner liner 9 disposed further on the inner side in the tire radial direction of the carcass. The tread 2 is composed of a cap tread 2a and a base tread 2b. In FIG. 1, W T1 is the thickness of the cap tread, W T2 is the thickness of the base tread, W S is the thickness of the sidewall, W C is the thickness of the clinch.

[0120] [A O ×W / T1] When the thickness (mm) of the tire member in this embodiment is W, A O The product of / T1 and W (A O ×W / T1) is preferably 0.180 or more.

[0121] A O From the viewpoint of the effects of the present invention, the value of ×W / T1 is preferably 0.200 or more, more preferably 0.360 or more, still more preferably 0.400 or more, still more preferably 0.700 or more, still more preferably 0.800 or more, still more preferably 1.150 or more, still more preferably 1.500 or more, still more preferably 2.000 or more, still more preferably 2.200 or more, still more preferably 4.000 or more, still more preferably 4.100 or more. On the other hand, A O The value of ×W / T1 is preferably 100.0 or less, more preferably 50.00 or less, more preferably 30.00 or less, still more preferably 10.00 or less, still more preferably 7.000 or less, still more preferably 5.000 or less.

[0122] W can be increased or decreased by increasing or decreasing the thickness of the corresponding tire member. A O The value of / T1 can be adjusted as described above. Therefore, the value of A O ×W / T1 can be adjusted by these combinations.

[0123] [Thickness of tire member] The thickness of the tire member is not particularly limited and may be a normal thickness.

[0124] (Thickness of tread) The total thickness of the tread is preferably, for example, 30.0 mm or less, more preferably 25.0 mm or less, still more preferably 20.0 mm or less, and particularly preferably 15.0 mm or less. Also, the thickness is more preferably 3.0 mm or more, more preferably 5.0 mm or more, and still more preferably 6.0 mm or more.

[0125] The ratio of the thickness of the cap tread to the total thickness of the tread can be, for example, 20% or more, and can be 30% or more, 40% or more, 50% or more, 60% or more. On the other hand, the ratio can be, for example, 90% or less, 85% or less. Also, the ratio of the thickness of the base tread to the total thickness of the tread can be, for example, 5% or more, and can be 10% or more, 15% or more. On the other hand, the ratio can be 80% or less, 70% or less, 60% or less, 50% or less, 40% or less. When there is an intermediate rubber layer, the ratio of the thickness of the intermediate rubber layer to the total thickness of the tread can be, for example, 1% or more, 5% or more, 10% or more. On the other hand, the ratio can be 60% or less, 40% or less, 35% or less.

[0126] (Thickness of the sidewall) The thickness of the sidewall is preferably 1.0 mm or more. The thickness is more preferably 1.2 mm or more, still more preferably 1.4 mm or more, and even more preferably 1.5 mm or more. On the other hand, the thickness of the sidewall is preferably 30.0 mm or less, more preferably 20.0 mm or less, still more preferably 10.0 mm or less, and even more preferably 8.0 mm or less.

[0127] (Thickness of the clinch) The thickness of the clinch portion is preferably 2.0 mm or more, more preferably 2.5 mm or more, still more preferably 3.0 mm or more, and even more preferably 3.5 mm or more. On the other hand, the thickness is preferably 10.0 mm or less, more preferably 8.0 mm or less, still more preferably 7.0 mm or less, and even more preferably 6.0 mm or less.

[0128] <Manufacturing> [Manufacture of the rubber composition] The rubber composition of this embodiment can be produced by a known method. For example, it can be produced by kneading each of the above components using a rubber kneading device such as an open roll or a closed kneader (Banbury mixer, kneader, etc.). The kneading process can be, for example, a method of kneading at a discharge temperature of 150 to 170°C for 3 to 10 minutes. This kneading process can also be carried out in multiple stages as desired. The conditions for each kneading at that time can be appropriately set by those skilled in the art.

[0129] [Manufacture of Tires] The tire rubber composition obtained above can be made into an uncured tire by extruding it according to the shape of a desired tire member at the uncured stage and then molding it together with other tire members on a tire molding machine by a normal method. By heating and pressurizing this uncured tire in a heating and pressurizing machine, the tire of this embodiment can be obtained. The conditions for heating and pressurizing are not particularly limited, and for example, a method of heating and pressurizing at 140 to 200°C for 15 to 180 minutes can be mentioned.

[0130] [Applications] In this specification, the tire having a tire member made of the rubber composition can be used for any tire, whether it is a pneumatic tire or a non-pneumatic tire, but it can be preferably used as a pneumatic tire. In addition, the tire can be used for various applications such as passenger car tires, large passenger car tires, large SUV tires, racing tires, heavy load tires such as trucks and buses, run-flat tires, and motorcycle tires. Note that a passenger car tire is a tire assumed to be mounted on an automobile running on four wheels and refers to a tire with a maximum load capacity of less than 1400 kg. Also, a heavy load tire refers to a tire with a maximum load capacity of 1400 kg or more. In this specification, the tire can be used for all-season tires, summer tires, and winter tires such as studless tires.

Examples

[0131] Examples (embodiments) that are considered preferable in implementation are shown below, but the scope of the present invention is not limited to the embodiments. Rubber compositions obtained according to Table 1 using various chemicals shown below were examined, and the results calculated based on the following evaluation methods are shown in Table 1.

[0132] <Various Chemicals> Epoxidized diene rubber 1: ENR25 (epoxidized natural rubber with an epoxidation rate of 25 mol%, manufactured by Kumparangasree Co., Ltd.) Epoxidized diene rubber 2: ENR50 (epoxidized natural rubber with an epoxidation rate of 50 mol%, manufactured by Kumparangasree Co., Ltd.) Isoprene rubber (IR rubber): TSR20 (natural rubber) Imidazole compound 1: Imidazole (manufactured by Tokyo Chemical Industry Co., Ltd.) Imidazole compound 2: 1,2-Dimethylimidazole (manufactured by Shikoku Chemicals Corporation) Imidazole compound 3: 1-Benzyl-2-methylimidazole (manufactured by Sigma-Aldrich) Carboxylic acid compound 1: Suberic acid (dicarboxylic acid, manufactured by Tokyo Chemical Industry Co., Ltd.) Carboxylic acid compound 2: Dodecanedioic acid (dicarboxylic acid, manufactured by Sigma-Aldrich) Carbon black: N234 (name according to ASTM D-1765 standard) Silica: Zeosil 1165MP (manufactured by Rhodia, N2SA: 160m 2 / g) Silane coupling agent: Triethoxyoctylsilane (manufactured by Degussa) Antioxidant: N-(1,3-dimethylbutyl)-N-phenyl-p-phenylenediamine (Santoflex 6-PPD, manufactured by Flexsys) Oil: Diana Process PS-32 (mineral oil, manufactured by Idemitsu Kosan Co., Ltd.)

[0133] Examples and Comparative Examples According to the formulation shown in Table 1, using a 1.7 L sealed Banbury mixer, various chemicals were kneaded at 150 °C for 5 minutes to obtain a kneaded product.

[0134] Each of the uncured rubber compositions obtained above is extruded into the shape of a cap tread, and an unvulcanized tire is produced by combining it with other tire members, and a test tire (195 / 65R15) is obtained by heating and pressing under the conditions described in Table 1.

[0135] <Longest relaxation time> From the cap tread of the test tire, a measurement sample with a height of 16 mm, a width of 40 mm, and a thickness of about 2 mm is cut out. As the measuring instrument, a dynamic viscoelasticity measuring device DMA+300 for high frequencies manufactured by Metrabiv is used. The measurement sample is fixed with a film shear type jig (the gap between the jigs is 2 mm), held at the measurement temperature (60 °C) for 5 minutes, then a 10% shear strain is applied and held, and the time change G(t) of the shear modulus is measured every 5 seconds for 20 minutes. From this measurement result, the longest relaxation time (time) T1 is obtained by Procedure X. That is, all the points of lnG(t) from 1000 seconds to 1200 seconds are plotted on a semi-logarithmic scale against the time t, approximated to a straight line by the least squares method, and the longest relaxation time (time) T1 is obtained from the slope (-(1 / T1)).

[0136] <Grip performance> Each test tire is mounted on all the wheels of a vehicle (domestic FF2000cc), and the braking distance from an initial speed of 100 km / h on a dry asphalt road surface is obtained and expressed as an index when the reference comparative example is 100. The larger the grip performance index, the shorter the braking distance, indicating excellent grip performance.

[0137]

Table 1

[0138]

Table 2

[0139] <Embodiment> Preferred embodiments are shown below.

[0140] [1] A rubber composition comprising a rubber component containing an epoxidized diene rubber, at least one selected from the group consisting of an imidazole compound and a polyvalent carboxylic acid compound, and an oil, wherein the content (parts by mass) A of the oil with respect to 100 parts by mass of the rubber component O divided by the longest relaxation time (hours) T1 obtained from Procedure X of the rubber composition (A O / T1) is 0.045 or more, preferably 0.050 or more, more preferably 0.090 or more, a rubber composition. [2] A O / T1 is 0.100 or more, preferably 0.200 or more, more preferably 0.300 or more, still more preferably 0.500 or more, still more preferably 1.000 or more, the rubber composition according to [1] above. [3] The rubber composition according to [1] or [2] above, wherein the rubber component contains an isoprene rubber of more than 0% by mass and less than 50% by mass, preferably more than 0% by mass and less than 45% by mass, still more preferably more than 0% by mass and 40% by mass or less. [4] The rubber composition according to any one of [1] to [3] above, wherein the epoxidation rate of the epoxidized diene rubber is 50 mol% or less, preferably less than 50 mol%, more preferably less than 30 mol%, still more preferably 25 mol% or less. [5] The rubber composition according to any one of [1] to [4] above, wherein the content of the filler is less than 45 parts by mass, preferably less than 20 parts by mass, still more preferably less than 5 parts by mass with respect to 100 parts by mass of the rubber component. [6] A tire having a tire member composed of the rubber composition according to any one of [1] to [5] above. [7] When the thickness (mm) of the tire member is W, A O the product of / T1 and W (A OThe tire according to [6] above, wherein (×W / T1) is 0.180 or more, preferably 0.200 or more and 100.0 or less, more preferably 0.360 or more and 50.00 or less, still more preferably 0.400 or more and 30.00 or less, still more preferably 0.700 or more and 10.00 or less, still more preferably 0.800 or more and 7.000 or less, still more preferably 1.150 or more and 5.000 or less, still more preferably 1.500 or more and 5.000 or less, still more preferably 2.000 or more and 5.000 or less, still more preferably 2.200 or more and 5.000 or less, still more preferably 4.000 or more and 5.000 or less, still more preferably 4.100 or more and 5.000 or less. [8] The tire according to [6] or [7] above, wherein the tire member is a cap tread.

Explanation of symbols

[0141] 1 Tire 2 Tread 2a Cap tread 2b Base tread 3 Sidewall 4 Wing 5 Clinch 6 Band 7 Breaker 8 Carcass 9 Inner liner R Rim W T1 Thickness of cap tread W T2 Thickness of base tread W S Thickness of sidewall W C Thickness of clinch CL Tire center line

Claims

1. A rubber composition comprising a rubber component containing an epoxidized diene rubber, at least one selected from the group consisting of an imidazole compound and a polyvalent carboxylic acid compound, and an oil, The content (parts by mass) A of the oil with respect to 100 parts by mass of the rubber component O is divided by the longest relaxation time (time) T obtained from Procedure X of the rubber composition 1 to obtain a value (A O / T 1 ), and the rubber composition is such that this value is 0.045 or more.

2. A O / T 1 is 0.100 or more, the rubber composition according to claim 1.

3. The rubber composition according to claim 1, wherein the rubber component contains an isoprene rubber in an amount of more than 0% by mass and less than 50% by mass.

4. The rubber composition according to claim 1, wherein the epoxidation rate of the epoxidized diene rubber is 50 mol% or less.

5. The rubber composition according to claim 1, wherein the content of the filler is less than 45 parts by mass with respect to 100 parts by mass of the rubber component.

6. A tire having a tire member composed of the rubber composition according to any one of claims 1 to 5.

7. When the thickness (mm) of the tire member is W, A O / T 1 The product of and W (A O ×W / T 1 ) is 0.180 or more. The tire according to claim 6

8. The tire according to claim 6, wherein the tire member is a cap tread.

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