tire

Abstract

To provide a tire excellent in low fuel consumption performance.SOLUTION: A tire comprising at least one rubber member composed of a crosslinked rubber containing a rubber component containing an isoprene-based rubber and a rubber containing a butadiene unit, silica, and a crosslinking agent, wherein the crosslinked rubber has a boron atom-containing group, and when the content (% by mass) of the isoprene-based rubber in the rubber component is AIR, the content (% by mass) of the rubber containing a butadiene unit is ABD, and the thickness (mm) of the rubber member is T, the following formula is satisfied: (1) AIR + ABD> 70 (2) (AIR + ABD) / T> 10.0 (where AIR> 10, ABD> 10) SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] In recent years, there has been an increasing demand for improved fuel economy in automobiles, and improved fuel economy performance by reducing rolling resistance is also required for tires that constitute automobiles. Patent Document 1 describes that fuel economy is improved by using a specific thermoplastic elastomer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2024-14499 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in response to environmental issues, further improvements in fuel efficiency are required.

[0005] An object of the present invention is to provide a tire that is excellent in fuel efficiency. [Means for solving the problem]

[0006] The present invention relates to the following tire. A tire having at least one rubber member composed of a rubber component containing an isoprene-based rubber and a rubber containing a butadiene unit, and a crosslinked rubber containing silica and a crosslinking agent, The crosslinked rubber has a boron atom-containing group, The content (mass%) of isoprene-based rubber in the rubber component is A IR The content (mass%) of the rubber containing the butadiene unit is A BD When the thickness (mm) of the rubber member is T, the tire satisfies the following formula: (1) AIR +A BD >70 (2)(A IR +A BD ) / T>10.0 (However, A IR >10, A BD >10) [Effects of the Invention]

[0007] According to the present invention, a tire with excellent fuel economy performance can be provided. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing a part of a cross section (upper right part of the cross section) taken along a plane including the tire rotation axis, of a tire according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] A tire according to one embodiment of the present invention will be described below. The tire according to this embodiment is the following tire. A tire having at least one rubber member composed of a rubber component containing an isoprene-based rubber and a rubber containing a butadiene unit, and a crosslinked rubber containing silica and a crosslinking agent, The crosslinked rubber has a boron atom-containing group, The content (mass%) of isoprene-based rubber in the rubber component is A IR The content (mass%) of the rubber containing the butadiene unit is A BD When the thickness (mm) of the rubber member is T, the tire satisfies the following formula: (1) A IR +A BD >70 (2)(A IR +A BD ) / T>10.0 (However, A IR >10, A BD >10)

[0010] While not intending to be bound by theory, the mechanism by which fuel economy is improved in the present invention is thought to be as follows. Specifically, (a) boron atoms, particularly boron atoms in neutral boron compounds, can interact with Si-OH groups on the silica surface, allowing polymers containing boron-containing groups to strongly interact with silica. This is thought to prevent silica particles from aggregating and improve silica dispersibility, thereby contributing to improved fuel economy. (b) When the isoprene-based rubber and the rubber containing butadiene units each contain a predetermined amount or more and their total amount exceeds 70 mass% so as to satisfy formula (1), the mixed polymer forms the main polymer and the proportion of double bonds is also increased. This makes it possible to increase the introduction rate of boron-containing groups into the mixed polymer, which is thought to improve silica dispersibility and contribute to improved fuel economy. (c) When the main polymer satisfies formula (1), as described in (b) above, the introduction rate of boron-containing groups can be increased, thereby increasing the thickness of the silica-adsorbed rubber. Meanwhile, the improved silica dispersion also promotes uniform silica dispersion, preventing the formation of non-uniform hard phases. Therefore, the thickness of the rubber component can be reduced relative to the total amount of the main polymer so as to satisfy formula (2), which is believed to contribute to improved fuel economy. These factors (a) to (c) work together to dramatically improve the fuel economy of the tire.

[0011] The value of the right side of formula (2) is preferably 12.0, and more preferably 14.0.

[0012] This is because it is believed that the effect of the present invention can be more effectively achieved by satisfying formula (2) under stricter conditions.

[0013] The boron content per 100 parts by mass of the rubber component is preferably 0.05 parts by mass or more.

[0014] The rubber containing butadiene units preferably contains styrene butadiene rubber.

[0015] The rubber containing butadiene units preferably contains a styrene-butadiene rubber and a butadiene rubber.

[0016] The content of the styrene-butadiene rubber in the rubber component is preferably 80% by mass or more.

[0017] The crosslinked rubber preferably contains a plasticizer, and the content of the plasticizer is preferably 15 parts by mass or less per 100 parts by mass of the rubber component.

[0018] It is preferable that the crosslinked rubber contains a plasticizer, the plasticizer contains a resin, and the amount of the resin is 2 parts by mass or more per 100 parts by mass of the rubber component.

[0019] At least one rubber selected from the group consisting of the isoprene-based rubber and the rubber containing butadiene units is preferably a modified rubber modified with a complex of a nitrogen-containing aromatic compound and a boron compound having a BH bond.

[0020] The nitrogen-containing aromatic compound is preferably at least one selected from the group consisting of pyridine, quinoxaline, pyrrole, pyrazine, pyrimidine, pyridazine, thiazole, oxazole, imidazole, pyrazole, isoxazole, isothiazole, triazole, furazan, oxadithiazole, thiadiazole, dioxazole, and dithiazole.

[0021] The crosslinked rubber preferably has crosslinking sites bonded via boron-oxygen bonds.

[0022] The crosslinking site preferably contains a group having a diboronic acid ester skeleton unit.

[0023] The rubber member is preferably one selected from a cap tread, a base tread, a sidewall, a clinch apex, a wing, and an inner liner, and is particularly preferably a cap tread.

[0024] In this specification, the upper and lower limit values ​​of "greater than or equal to," "less than or equal to," and "to" used to describe a numerical range can be arbitrarily combined, and in addition, the numerical values ​​in the examples can also be combined with the upper and lower limit values. Furthermore, when a numerical range is specified by "to," it means that both end values ​​are included unless otherwise specified. Furthermore, in this specification, a numerical range indicated as including both end values ​​is understood to simultaneously indicate a numerical range that does not include either end value, or even a numerical range that does not include both end values, as long as it does not contradict the spirit of the present invention.

[0025] [Definition] "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.

[0026] Unless otherwise specified, the "dimensions of each part of the tire" are values ​​that are specified when the tire appears on its outer surface in a normal state, while those that exist inside the tire or on a cut surface of the tire are values ​​that are specified when, for example, the tire is cut along a plane that includes the tire rotation axis and the cut tire piece is maintained within the rim width of a normal rim.

[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 refers to the "maximum air pressure," for ETRTO, it refers to "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. If multiple normal internal pressures of 250kPa or more are 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 tire's radial direction 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] "Tire component thickness" refers to the maximum thickness (mm) of the tire component in question in a cross section of the tire taken along a plane including the tire's rotation axis. The maximum thickness is measured by cutting the tire along a plane including the tire's rotation axis to create a tire specimen, and maintaining the normal rim width between the beads of the tire specimen. The thickness is the average of the thicknesses measured at five locations after rotating the tire 72 degrees each time.

[0033] When the thickness of a tire component is substantially uniform in the cross section of the tire, the thickness at a predetermined location is taken as the thickness of the tire component. That is, (1) for a component whose thickness in the tire radial direction can be recognized on the tire centerline, the thickness of the component is taken as the thickness of the component, and (2) for a tire component whose thickness cannot be recognized as described in (1) above, for a component whose thickness at the tire's maximum width position in the tire rotational axis direction can be recognized, the thickness of the component is taken as the thickness of the component. Examples of tire components in (1) above include a cap tread, base tread, full band, belt, carcass, inner liner, etc., and examples of tire components in (2) above include a sidewall, etc.

[0034] On the other hand, if the thickness of a tire component varies in the cross section of the tire, the thickness is determined taking into consideration a normal thickness determination method for that tire component, such as a clinch apex or wing.

[0035] The "cap tread thickness" is the thickness of the tire in the radial direction on the tire centerline in a cross section of the tire taken along a plane including the tire rotation axis. This corresponds to T1 in Figure 1.

[0036] The "thickness of the inner liner" is the thickness in the radial direction of the tire on the center line of the tire in a cross section of the tire taken along a plane including the tire rotation axis. This corresponds to T3 in Figure 1.

[0037] The "sidewall thickness" is the thickness at the tire's widest point in the tire's axis direction in a cross section of the tire taken along a plane including the tire's axis of rotation. This corresponds to T4 in Figure 1.

[0038] The "thickness of the clinch apex" is the thickness measured along a normal to the main body of the carcass that passes through the point where the sidewall and the clinch apex meet on the outer surface of the tire. In Figure 1, P1 is the point where the sidewall and the clinch apex meet on the outer surface of the tire, L1 is the normal to the main body of the carcass that passes through point P1, and T5 is the thickness of the clinch apex measured along the normal L1.

[0039] "Wing thickness" is the thickness measured along a normal to the tire outer surface that passes through the point where the contour line of the tread on the outer side in the tire width direction intersects with the contour line of the sidewall on the outer side in the tire radial direction. In Figure 1, P2 is the point where the contour line of the tread on the outer side in the tire width direction intersects with the contour line of the sidewall on the outer side in the tire radial direction, L2 is the normal to the tire outer surface that passes through point P2, and T6 is the thickness of the wing measured along the normal line L2.

[0040] "Plasticizer" is a material that imparts plasticity to the rubber component, and is a concept that includes both plasticizers that are liquid (fluid state) at 25°C and plasticizers that are solid at 25°C. Examples of plasticizers include resins, oils, liquid rubbers, and ester-based plasticizers. "Plasticizer content" also includes the amount of plasticizer in the rubber component that has been extended by the plasticizer.

[0041] [Measurement method] "Styrene content" is measured by pyrolysis gas chromatography and NMR measurement ( 1 H-NMR and 13 The amount of components such as "styrene content" is calculated by C-NMR. Unlike physical property values ​​such as complex modulus (E*), the amount of components such as "styrene content" has a true value that is independent of the measurement method, so it is preferable to use a measurement method with as high accuracy as possible. In this specification, "pyrolysis gas chromatography" refers to a method in which a sample is heated in a pyrolysis device, 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.

[0042] "Vinyl content (amount of 1,2-bonded butadiene units)" can be measured by pyrolysis gas chromatography or NMR measurement ( 1 H-NMR and 13 It is calculated using C-NMR. As with the "styrene content," there is a true value for the "vinyl content" that is independent of the measurement method, so it is preferable to use a measurement method with as high accuracy as possible.

[0043] "Cis content (cis-1,4-bonded butadiene unit amount)" is measured by infrared absorption spectroscopy or NMR measurement ( 1 H-NMR and 13 This is a value measured by C-NMR and is applied to rubber components that have repeating units derived from butadiene, such as BR. As with the "styrene content," the "cis content" also has a true value that is independent of the measurement method, so it is preferable to use a measurement method with as high accuracy as possible.

[0044] The "glass transition temperature Tg" is a value determined by differential scanning calorimetry (DSC) in accordance with JIS K 7121, and is applied to, for example, SBR. For example, when the SBR contains an extender oil, the glass transition temperature Tg is measured in accordance with JIS K 6229 on a sample after removing the extender oil with acetone.

[0045] The "weight average molecular weight (Mw)" can be determined by converting the measured value into standard polystyrene equivalents 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, SBR, BR, plasticizers, etc.

[0046] The "nitrogen adsorption specific surface area (N2SA) of carbon black" is measured in accordance with JIS K 6217-2:2017.

[0047] The "nitrogen adsorption specific surface area (N2SA) of silica" is measured by the BET method in accordance with ASTM D3037-93.

[0048] "Average primary particle size" is a value calculated 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 x (particle area) / π}). Average primary particle size applies to silica, carbon black, etc.

[0049] The "softening point of the resin" is the temperature at which the ball drops when the softening point specified in JIS K 6220-1:2015 7.7 is measured using a ring and ball softening point tester.

[0050] [tire] A tire according to one embodiment of the present invention will be described below with reference to the accompanying drawings. However, the drawings used merely illustrate one embodiment, and the present invention is not limited to these drawings.

[0051] The tire according to the present embodiment is a tire including at least one rubber member made of a predetermined crosslinked rubber, and the content (mass %) of isoprene-based rubber in the rubber component contained in the crosslinked rubber is A IR , the content (mass%) of rubber containing butadiene units is A BD When the thickness (mm) of the rubber member is T, the tire satisfies the following formula: (1) A IR +A BD >70 (2)(A IR +A BD ) / T>10.0 (However, A IR >10, A BD >10)

[0052] The rubber member made of a predetermined crosslinked rubber is not particularly limited, and various tire members can be mentioned, specifically, a cap tread, a base tread, a sidewall, a clinch apex, a wing, an inner liner, etc. Among these, the cap tread, etc. is preferred.

[0053] Fig. 1 is a schematic diagram showing a portion of a cross section (upper right portion of the cross section) of a tire according to this embodiment, taken along a plane including the tire rotation axis. Fig. 1 shows a cap tread 1, an inner liner 3, a sidewall 4, a clinch apex 5, and a wing 6. In Fig. 1, the thickness of the cap tread is indicated as T1, the thickness of the inner liner 3 as T3, the thickness of the sidewall 4 as T4, the thickness of the clinch apex 5 as T5, and the thickness of the wing 6 as T6.

[0054] <Formula (1)> The value of the right side of the formula (1) is preferably 75, more preferably 80, even more preferably 85, even more preferably 90, and even more preferably 95. IR +A BD A value of 100 is particularly preferred.

[0055] Regarding equation (1), the value of the left side, A IR +A BD can be adjusted by increasing or decreasing the content of isoprene-based rubber and / or the content of rubber containing butadiene units, respectively.

[0056] A is the content of isoprene rubber in the rubber component IR (mass%) is more than 10, and the preferred range thereof will be described later. BD (mass%) is greater than 10, and its preferred value will be described later. IR (mass%) is the total content of IR rubber, including specially modified IR rubber, and A BD (mass %) is the total content of rubber containing specifically modified butadiene units.

[0057] <Formula (2)> The value of the right side of the formula (2) is preferably 11.0, more preferably 12.0, even more preferably 13.0, and still more preferably 14.0. IR +A BDThere is no particular upper limit to the value of ) / T, but it can vary depending on the type of rubber member. When the rubber member is an inner liner, which can be the thinnest, the upper limit is, for example, about 200.

[0058] Regarding the left side of equation (2), the numerator A IR +A BD corresponds to the left side of equation (1), so its adjustment is the same as above. On the other hand, the denominator, T, is the thickness of the rubber member, so it can be adjusted by increasing or decreasing the thickness of the rubber member. Therefore, the value of the left side of equation (2), (A IR +A BD ) / T can be adjusted by increasing or decreasing the numerator and denominator as appropriate.

[0059] The value of T is preferably 0.5 mm or more, more preferably 0.7 mm or more, and even more preferably 1 mm or more, while the value is preferably 10 mm or less, more preferably less than 10 mm, even more preferably 9 mm or less, and even more preferably 8 mm or less.

[0060] The value of T may vary depending on the type of rubber member. In the case of a cap tread, for example, the thickness of the cap tread is preferably 3 mm or more, more preferably 4 mm or more, and even more preferably 5 mm or more. There is no particular upper limit, but it is preferably 10 mm or less, more preferably less than 10 mm, even more preferably 9 mm or less, and even more preferably 8 mm or less.

[0061] In the case of an inner liner, for example, the thickness of the inner liner is preferably 0.5 mm or more, more preferably 0.7 mm or more, and even more preferably 1 mm or more. There is no particular upper limit, but it is preferably 2.5 mm or less, more preferably 2 mm or less, and even more preferably 1.5 mm or less.

[0062] In the case of the sidewall, for example, the thickness of the sidewall is preferably 2 mm or more, more preferably 2.5 mm or more, and even more preferably 3 mm or more. There is no particular upper limit, but it is preferably 6 mm or less, more preferably 5.5 mm or less, and even more preferably 4 mm or less.

[0063] In the case of wings, for example, the thickness of the wings is preferably 3 mm or more, more preferably 3.5 mm or more, and even more preferably 4 mm or more. There is no particular upper limit, but it is preferably 5 mm or less, more preferably 4.5 mm or less, and even more preferably 4.3 mm or less.

[0064] In the case of a clinch apex, for example, the thickness of the clinch apex is preferably 4 mm or more, more preferably 4.5 mm or more, and even more preferably 5 mm or more. There is no particular upper limit, but it is preferably 8 mm or less, more preferably 7 mm or less, and even more preferably 6 mm or less.

[0065] So, for example, A IR +A BD is 100% by mass, the range of the value on the left side of formula (2) is automatically determined from the range of the value of T. In that case, the "equal to or less" in the upper limit of the value of T can be read as "less than" if necessary for consistency with the inequality sign in formula (2).

[0066] [Crosslinked rubber] The crosslinked rubber constituting the rubber member of the tire according to the present embodiment will be described below. The crosslinked rubber includes a rubber component containing an isoprene-based rubber and a rubber containing butadiene units, silica, and a crosslinking agent, and the crosslinked rubber has a boron atom-containing group.

[0067] Crosslinked rubbers having boron atom-containing groups can be obtained, for example, by using, as raw materials for the crosslinked rubber, (1) a diene rubber previously modified with a boron atom-containing group (hereinafter referred to as a "specifically modified diene rubber") as at least a part of the rubber component to form a boron atom-containing crosslinking site, or (2) if the rubber component does not contain a specific modified diene rubber, by using a compound that forms a boron atom-containing crosslinking site (hereinafter referred to as a "boron crosslink-forming compound") to form a boron atom-containing crosslinking site. Furthermore, (1) and (2) above may be used in combination. In the crosslinked rubber having boron atom-containing groups thus obtained, the presence of the boron atom-containing groups is thought to contribute to the realization of the effects of the present invention by enhancing crosslinking with the double bonds of the polymer and enhancing interaction with silica. Examples of the crosslinking moiety containing a boron atom include a crosslinking moiety bonded via a boron-oxygen bond, a crosslinking moiety bonded via a boron-sulfur bond, a crosslinking moiety bonded via a boron-carbon bond, and a crosslinking moiety bonded via a boron-nitrogen bond. Therefore, the crosslinked rubber having a boron atom-containing group preferably has these crosslinking moieties. Among these, the crosslinked rubber having a boron atom-containing group preferably has a crosslinking moiety bonded via a boron-oxygen bond.

[0068] When a boron cross-linking compound is used as a raw material for the cross-linked rubber, the boron content is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1.0 part by mass or more, and still more preferably 1.5 parts by mass or more, per 100 parts by mass of the rubber component, from the viewpoint of the effects of the present invention. There is no particular upper limit for the boron content, but 5 parts by mass is usually sufficient.

[0069] <Rubber component> The rubber component is a rubber component containing an isoprene-based rubber (IR-based rubber) and a rubber containing butadiene units.

[0070] Examples of rubbers containing butadiene units include diene rubbers such as styrene butadiene rubber (SBR), butadiene rubber (BR), styrene isoprene butadiene rubber (SIBR), and acrylonitrile butadiene rubber (NBR). The rubbers containing butadiene units may be used alone or in combination of two or more. The rubbers containing butadiene units preferably contain SBR, or preferably contain SBR and BR.

[0071] The rubber component may also contain diene rubbers such as chloroprene rubber (CR) and non-diene rubbers such as butyl rubber, ethylene propylene rubber, polynorbornene rubber, silicone rubber, chlorinated polyethylene rubber, fluororubber (FKM), acrylic rubber (ACM), hydrin rubber, etc. These diene rubbers and non-diene rubbers may be used either individually or in combination of two or more.

[0072] The rubber component may be composed of an IR rubber and an SBR, or may be composed of an IR rubber, an SBR and an BR.

[0073] (Specially modified diene rubber) At least one of the diene rubbers is preferably a diene rubber modified with a group containing a boron atom, i.e., a specific modified diene rubber. The specific modified diene rubber may be used alone or in combination of two or more.

[0074] The specific modified diene rubber can be obtained by various methods, but typically can be obtained by treating a diene rubber with a borane complex. Examples of such borane complexes include complexes of a nitrogen-containing aromatic compound and a boron compound having a BH bond. Examples of the nitrogen-containing aromatic compound include at least one selected from the group consisting of pyridine, quinoxaline, pyrrole, pyrazine, pyrimidine, pyridazine, thiazole, oxazole, imidazole, pyrazole, isoxazole, isothiazole, triazole, furazan, oxadithiazole, thiadiazole, dioxazole, and dithiazole. These nitrogen-containing aromatic compounds may have a substituent (e.g., an alkyl group having 1 to 10 carbon atoms). The boron compound having a BH bond may be any compound having at least one BH bond, and examples of such compounds include borane (BH), alkylborane, dialkylborane, arylborane, diarylborane, and alkylarylborane. Examples of the borane complex include pyridine borane, picoline borane, pyrrole borane, and aniline borane.

[0075] In the complex of the nitrogen-containing aromatic compound and the borane compound, boron bonds to the double bond of the polymer, and the nitrogen-containing aromatic compound portion strongly interacts with the filler such as silica, resulting in the crosslinked rubber containing a boron atom-containing group.It is believed that the effect of the present invention, namely, improved fuel economy, is achieved because the dispersibility of the filler is improved.

[0076] When the specific modified diene rubber is used, the boron content is preferably 0.05 parts by mass or more, more preferably 0.07 parts by mass or more, and even more preferably 0.09 parts by mass or more, per 100 parts by mass of the rubber component, from the viewpoint of the effects of the present invention. On the other hand, there is no particular limitation on the upper limit of the content, but usually, even if it is 0.3 parts by mass, the effect can be sufficiently exhibited.

[0077] As the specially modified diene rubber, specially modified IR rubbers such as specially modified NR, specially modified SBR, and specially modified BR can be suitably used.

[0078] (Boron bridge-forming compound) Instead of using the specific modified diene rubber, or together with the specific modified diene rubber, a boron crosslink-forming compound can be used, because such a compound can also produce a crosslinked rubber having a boron atom-containing group.

[0079] Any boron crosslinking compound can be used as long as it is a compound that can obtain a crosslinked rubber having a boron atom-containing group. Here, an example of a crosslinked rubber having a boron atom-containing group is a crosslinked rubber having a crosslinking moiety bonded via a boron-oxygen bond. The crosslinking moiety preferably contains a group having a diboronic acid ester skeleton unit. Examples of compounds that form such crosslinking moieties include compounds represented by the formula: [ka] (However, X 1 is a single bond or any divalent group, and Y 1 and Y 2 are each independently a single bond or a divalent hydrocarbon group. Examples of such compounds include diboronic acid ester compounds represented by the following partial structural formula: These compounds have a functional group (mercapto group) that bonds with the double bond of a polymer, and can therefore be used as crosslinking agents. When crosslinking between polymers is performed using the diboronic acid ester compound, the crosslinking site has the following partial structural formula: [ka] (wherein the symbols have the same meanings as defined above) The diboronic acid ester backbone unit is represented by the formula:

[0080] X 1Examples of the divalent group in the formula include linear or branched aliphatic groups having 1 to 10 carbon atoms (alkylene groups, alkenylene groups, alkynylene groups); and aromatic groups having 6 to 20 carbon atoms (1,2-phenylene groups, 1,3-phenylene groups, 1,4-phenylene groups, 1,4-naphthylene groups, 1,5-naphthylene groups, 2,6-naphthylene groups, 4,4'-biphenylene groups, etc.). The aliphatic groups and aromatic groups include -O-, -S-, -OC(=O)-, -C(=O)-O-, -OC(=O)-O-, -NR 1 -C(=O)-, -C(=O)-NR 1 -, -NR 1 - or -C(=O)- may be present. 1 represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. 1 Examples of the alkyl group include a 1,4-phenylene group. 1 and Y 2 The divalent hydrocarbon group in the formula (I) can be an alkylene group having 1 to 3 carbon atoms, and among these, a methylene group is preferred.

[0081] The boron cross-linking compounds may be used alone or in combination of two or more.

[0082] The content of the boron cross-linking compound is preferably more than 0 part by mass, more preferably more than 1 part by mass, even more preferably more than 2 parts by mass, even more preferably more than 3 parts by mass, and still more preferably 5 parts by mass or more, relative to 100 parts by mass of the rubber component. On the other hand, the content is preferably less than 50 parts by mass, more preferably less than 40 parts by mass, even more preferably less than 35 parts by mass, and still more preferably less than 30 parts by mass.

[0083] (radical initiator) When a boron crosslinking compound is blended, it is preferable to blend a radical initiator. Examples of radical initiators include inorganic peroxides such as potassium persulfate, sodium persulfate, ammonium persulfate, potassium perphosphate, and hydrogen peroxide; organic peroxides such as t-butyl peroxide, cumene hydroperoxide, p-menthane hydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, dibenzoyl peroxide, 3,5,5-trimethylhexanoyl peroxide, and t-butylperoxyisobutyrate; and azo compounds such as 2,2'-azobisisobutyronitrile (AIBN), azobis-2,4-dimethylvaleronitrile, azobiscyclohexanecarbonitrile, and methyl azobisisobutyrate. These radical initiators may be used alone or in combination of two or more. Among these, the radical initiator is preferably an azo compound, and more preferably 2,2'-azobisisobutyronitrile.

[0084] The amount of the radical initiator is not particularly limited, but is preferably more than 0.05 parts by mass, more preferably more than 0.07 parts by mass, and even more preferably 0.1 parts by mass or more, per 100 parts by mass of the rubber component. On the other hand, for example, 3 parts by mass is sufficient as the content.

[0085] (IR rubber) Examples of IR rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. Examples of NR include SIR20, RSS#3, TSR20, and SVR-L, which are commonly used in the tire industry. Examples of IR are not particularly limited, and examples of IR include IR2200, which are commonly used in the tire industry. Examples of modified NR include deproteinized natural rubber (DPNR) and highly purified natural rubber (UPNR). Examples of modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Examples of modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. Isoprene rubbers may be used alone or in combination.

[0086] (SBR) Styrene-butadiene rubber (SBR) is not particularly limited and includes, for example, unmodified emulsion-polymerized styrene-butadiene rubber (E-SBR) and solution-polymerized styrene-butadiene rubber (S-SBR), as well as modified SBRs such as modified emulsion-polymerized styrene-butadiene rubber (modified E-SBR) and modified solution-polymerized styrene-butadiene rubber (modified S-SBR). Modified SBRs include those with modified ends and / or main chains, and those coupled with tin or silicon compounds (condensates, those with branched structures, etc.). Modified SBRs also include SBRs modified with borane complexes, as described below. Hydrogenated versions of these SBRs (hydrogenated SBRs) can also be used. SBRs include oil-extended types, in which flexibility is adjusted by adding extender oil, and non-oil-extended types, in which no extender oil is added. Either of these can be used. Examples of such SBR that can be used include those manufactured by JSR Corporation, Asahi Kasei Chemicals Corporation, Zeon Corporation, and ZS Elastomers Co., Ltd. One type of SBR can be used alone, or two or more types can be used in combination.

[0087] The styrene content of SBR is preferably more than 15% by mass, more preferably more than 20% by mass, and even more preferably more than 23% by mass. From the viewpoint of fuel economy, the styrene content is preferably less than 40% by mass, more preferably less than 35% by mass, and even more preferably less than 30% by mass. The styrene content of SBR is a value measured by the above-mentioned method.

[0088] The vinyl content of SBR (amount of 1,2-bonded butadiene units) is preferably more than 10 mol%, more preferably more than 30 mol%, and even more preferably more than 50 mol%. The vinyl content is preferably less than 80 mol%, preferably less than 70 mol%, and more preferably less than 60 mol%. The vinyl content of SBR is a value measured by the above-mentioned method.

[0089] (BR) The BR is not particularly limited, and examples thereof include those commonly used in the tire industry, such as BR with a high cis content, BR containing 1,2-syndiotactic polybutadiene crystals (SPB-containing BR), butadiene rubber synthesized using a rare earth catalyst (rare earth-based BR), tin-modified butadiene rubber modified with a tin compound (tin-modified BR), and other modified butadiene rubbers (modified BR).Commercially available BRs include those from UBE Corporation, JSR Corporation, Asahi Kasei Corporation, and Zeon Corporation. The modified BR may be any BR having a functional group that interacts with a filler such as silica. Examples include terminal-modified BR (terminal-modified BR having the functional group at the terminal) in which at least one terminal of the BR has been modified with a compound (modifier) ​​having the functional group, main-chain-modified BR having the functional group in the main chain, main-chain terminal-modified BR having the functional group in the main chain and at least one terminal (for example, main-chain terminal-modified BR having the functional group in the main chain and at least one terminal modified with the modifier), and terminal-modified BR modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and having a hydroxyl group or epoxy group introduced therein. Examples of the functional group include an amino group, an amide group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a urea group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a sulfide group, a disulfide group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imido group, a hydrazo group, an azo group, a diazo group, a carboxyl group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group, and an epoxy group. These functional groups may have a substituent. Among these, an amino group (preferably an amino group in which a hydrogen atom of the amino group is substituted with an alkyl group having 1 to 6 carbon atoms), an alkoxy group (preferably an alkoxy group having 1 to 6 carbon atoms), and an alkoxysilyl group (preferably an alkoxysilyl group having 1 to 6 carbon atoms) are preferred. BR may be used alone or in combination of two or more types.

[0090] The cis content of BR is preferably more than 25 mol%, more preferably more than 30 mol%, and even more preferably more than 35 mol%. On the other hand, the cis content is preferably less than 60 mol%, more preferably less than 50 mol%, and even more preferably less than 40 mol%. The cis content of BR can be measured by the above-mentioned method.

[0091] As the BR, for example, products from UBE Corporation, JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Corporation, etc. can be used.

[0092] (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.

[0093] 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.

[0094] 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.

[0095] 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 conversion, high heat conversion, high pressure conversion, electromagnetic wave conversion, critical fluid conversion, and combinations thereof.

[0096] 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.

[0097] Whether the raw material for a polymer is derived from biomass can be determined by the pMC (percent modern carbon) measured in accordance with ASTM D6866-10.

[0098] pMC is the modern standard reference14 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.

[0099] 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 14 C 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 element.

[0100] 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.

[0101] this 14 C is typically measured using accelerator mass spectrometry based on a tandem accelerator. 13 C concentration ( 13 C / 12 C). 14C 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. 14 The 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.

[0102] 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 above-mentioned biomass ratio of 0%.

[0103] 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.

[0104] (Content of each rubber in the rubber component) The content of the IR rubber in the rubber component is preferably more than 10% by mass, more preferably more than 15% by mass, and even more preferably 20% by mass or more. On the other hand, the content is preferably less than 90% by mass, more preferably less than 85% by mass, and even more preferably 80% by mass or less. The content of the IR rubber also includes the specifically modified IR rubber. The IR rubber may consist solely of the specifically modified IR rubber.

[0105] The content of SBR in the rubber component is preferably more than 10% by mass, more preferably more than 15% by mass, and even more preferably 20% by mass or more. On the other hand, the content is preferably less than 90% by mass, more preferably less than 85% by mass, and even more preferably 80% by mass or less. The content of SBR also includes specifically modified SBR. The SBR may consist solely of specifically modified SBR. In another embodiment in which SBR is the main component of the rubber component, the SBR is, for example, preferably 80% by mass or more, and may be 85% by mass or more.

[0106] The content of BR in the rubber component is preferably less than 50% by mass, more preferably less than 30% by mass, and even more preferably 20% by mass or less. Alternatively, the content may be 0% by mass, more than 0%, more than 10%, or more than 15% by mass. The content of BR also includes the specifically modified BR. The BR may consist solely of the specifically modified BR.

[0107] <Filler> The crosslinked rubber contains silica as a filler. In addition to silica, fillers commonly used in the tire industry, such as carbon black, can be used. Examples of fillers other than silica and carbon black include aluminum hydroxide, calcium carbonate, alumina, clay, and talc. The filler preferably contains silica and carbon black, and may consist solely of silica and carbon black. When the filler contains silica and carbon black, the ratio of the silica content (parts by mass) to the carbon black content (parts by mass) is preferably greater than 1. This ratio is more preferably greater than 5, even more preferably greater than 10, and even more preferably greater than 12.

[0108] (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 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 a silica-containing product. Among these, hydrated silica prepared by a wet method is preferred because it contains a large number of silanol groups. Silica can be used alone or in combination of two or more types.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] The nitrogen adsorption specific surface area (N2SA) of the silica is preferably 50 m 2 / g, more preferably 100m 2 / g, more preferably 150m2 / g, particularly preferably 170m 2 The upper limit of the N2SA of silica is not particularly limited, but is preferably 350 m 2 / g, more preferably less than 250m 2 / g, more preferably less than 200m 2 / g. By setting it within the above range, cut resistance tends to be improved. The N2SA of silica is measured by the above-mentioned measurement method.

[0113] From the viewpoint of the effects of the present invention, the average primary particle diameter of silica is preferably more than 10 nm, more preferably more than 12 nm, even more preferably more than 14 nm, and particularly preferably more than 16 nm.Furthermore, the average primary particle diameter is preferably less than 24 nm, more preferably less than 22 nm, and even more preferably less than 20 nm.The average primary particle diameter of silica is measured by the above-mentioned measurement method.

[0114] When silica is contained, the content per 100 parts by mass of the rubber component is not particularly limited, but from the viewpoint of obtaining the effects of the present invention, it is preferably more than 40 parts by mass, more preferably more than 50 parts by mass, and even more preferably more than 60 parts by mass. Also, from the viewpoints of dispersibility and processability of silica, the content is preferably less than 200 parts by mass, more preferably less than 150 parts by mass, and even more preferably less than 100 parts by mass.

[0115] (Silane coupling agent) When silica is used, it is preferable to further contain a silane coupling agent. The silane coupling agent is not particularly limited, and examples thereof include bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)disulfide, bis(4-triethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthio Examples of suitable silanes include sulfide-based silanes such as carbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based silanes such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and Momentive's NXT and NXT-Z; vinyl-based silanes such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based silanes such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based silanes such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based silanes such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based silanes such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Commercially available products that can be used include those manufactured by Evonik Degussa, Momentive, Shin-Etsu Silicones Co., Ltd., Tokyo Chemical Industry Co., Ltd., AZMAX Corporation, and Dow Corning Toray Co., Ltd. The silane coupling agents may be used alone or in combination of two or more.

[0116] When containing silane coupling agent, the content of silane coupling agent is preferably more than 1 part by mass, more preferably more than 3 parts by mass, even more preferably more than 5 parts by mass, and even more preferably more than 7 parts by mass, based on 100 parts by mass of silica.On the other hand, the content is preferably less than 20 parts by mass, more preferably less than 18 parts by mass, even more preferably less than 16 parts by mass, and even more preferably less than 14 parts by mass.By making it within the above range, the dispersibility of silica tends to improve.

[0117] (carbon black) The carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, N660, and N762. From the perspective of life cycle assessment, the raw material for carbon black may be a biomass material such as lignin or vegetable oil. Furthermore, carbon black may be produced by combustion, such as in a furnace, 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.

[0118] The average primary particle size of carbon black is preferably greater than 15 nm, more preferably greater than 18 nm, and even more preferably greater than 20 nm. On the other hand, the average primary particle size is preferably less than 50 nm, more preferably less than 40 nm, and even more preferably less than 30 nm. The average primary particle size of carbon black is measured by the above-mentioned measurement method.

[0119] The nitrogen adsorption specific surface area (N2SA) of the carbon black is not particularly limited, but from the viewpoint of obtaining sufficient reinforcement and good abrasion resistance, it is preferred that the N2SA be 30 m 2 / g or more is preferable, and 60m 2 / g is more preferable, and 80m 2 / g is more preferable, and 100m 2 In addition, from the viewpoint of excellent dispersibility and low heat generation, the N2SA has a viscosity of 300 m / g or more. 2 / g is preferable, and 200m 2 / g is more preferable, and 150m 2 / g is more preferable, and 120m 2 It is more preferable that the N of carbon black in this specification is less than 1 / g. 2 SA is the value measured by the above method.

[0120] The carbon black may include recycled carbon black. 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 that recycled carbon black can be 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 and Commercial Carbon Black, Powder Technology 160 (2005) pp. 190-193).

[0121] Recycled carbon black may lack functional groups on its surface, or may be treated to include functional groups on its surface. The 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 by 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 No. 6,856,781, carbon black obtained by 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 according to this embodiment also includes carbon black treated to include functional groups on its surface. Recycled carbon black may be used alone or in combination.

[0122] The carbon black content is, for example, more than 1 part by mass, preferably more than 3 parts by mass, and more preferably 5 parts by mass or more, per 100 parts by mass of the rubber component. Meanwhile, the total content is preferably less than 200 parts by mass, more preferably less than 15 parts by mass, and even more preferably less than 10 parts by mass. When the carbon black content is within the above range, sufficient reinforcement and good dispersion in the rubber are obtained, and sufficient grip performance tends to be obtained.

[0123] <Other compounding agents> In addition to the rubber component and filler, the rubber composition may contain, as appropriate, compounding agents that are conventionally commonly used in the tire industry, such as plasticizers, compatibilizers, processing aids, vulcanized rubber particles, wax, stearic acid, zinc oxide, antioxidants, crosslinking agents, and vulcanization accelerators.

[0124] (plasticizer) A plasticizer is a material that imparts plasticity to rubber components and encompasses both liquid and solid plasticizers at 25°C. Examples of plasticizers include resins, oils, liquid rubbers, and ester-based plasticizers. These plasticizers may be derived from mineral resources such as petroleum and natural gas, biomass-derived materials, or naphtha recycled from rubber and non-rubber products. Low-molecular-weight hydrocarbon components obtained by pyrolysis and extraction of used tires or products containing various components may also be used as plasticizers. Plasticizers may be used singly or in combination.

[0125] <Resin> Of the other compounding ingredients, the rubber composition preferably contains a resin. The resin 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, dicyclopentadiene resins, C5C9 resins, and terpene resins are preferred, with C5C9 resins being more preferred. The resins may be used alone or in combination of two or more.

[0126] Aromatic vinyl resin The term "aromatic vinyl resin" refers to a resin containing at least one aromatic vinyl compound selected from the group consisting of styrene, α-methylstyrene, vinyltoluene, p-chlorostyrene, etc., as the monomer component with the largest content, preferably at least 50 mol %, and may be hydrogenated or modified. As the aromatic vinyl resin, a homopolymer of α-methylstyrene or styrene or a copolymer of α-methylstyrene and styrene is preferred, and a copolymer of α-methylstyrene and styrene is more preferred, because they are economical, easy to process, and have excellent heat generation properties. As the aromatic vinyl resin, commercially available products available from, for example, Kraton, Eastman Chemical, Mitsui Chemicals, Inc., etc., can be used. One type of resin may be used alone, or two or more types may be used in combination.

[0127] Dicyclopentadiene resin The term "dicyclopentadiene-based resin" refers to a resin containing dicyclopentadiene (DCPD) as the monomer component with the highest content, and may be a hydrogenated or modified resin. Examples of dicyclopentadiene-based resins include DCPD / C9 resins obtained by copolymerizing dicyclopentadiene with the C9 fraction, with DCPD / C9 resins being preferred. Examples of DCPD resins that can be used include those commercially available from ExxonMobil Corporation, ENEOS Corporation, Nippon Zeon Co., Ltd., Maruzen Petrochemical Co., Ltd., and the like. These resins may be used singly or in combination of two or more.

[0128] ·C9 resin The term "C9 resin" refers to a resin obtained by polymerizing a C9 fraction. It may be a C9 fraction polymerized alone or a copolymer obtained by copolymerizing a C9 fraction with other components. For example, a resin obtained by copolymerizing dicyclopentadiene (DCPD) with a C9 fraction is called a DCPD / C9 resin. It may also be a hydrogenated or modified version of such a resin. Examples of C9 fractions include at least one petroleum fraction having 8 to 10 carbon atoms selected from the group consisting of vinyltoluene, alkylstyrene, coumarone, indene, methylindene, dicyclopentadiene, etc. Specific examples of C9 resins include coumarone-indene resin, coumarone resin, and indene resin. These resins may be used alone or in combination.

[0129] ·C5 resin "C5 resin" refers to a resin obtained by polymerizing a C5 fraction other than dicyclopentadiene, and may be a hydrogenated or modified version of such a resin. Examples of C5 fractions other than dicyclopentadiene include at least one petroleum fraction having 4 to 5 carbon atoms selected from the group consisting of cyclopentadiene, isoprene, pentane, isopentane, neopentane, pentene, pentadiene, etc. Such resins may be used alone or in combination of two or more.

[0130] C5C9 resin The term "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be a hydrogenated or modified resin. Examples of C5C9 resins that can be used include those commercially available from Tosoh Corporation, LUHUA, and the like. One type of resin may be used alone, or two or more types may be used in combination.

[0131] Terpene resin Terpene resins refer to resins containing at least one terpene compound selected from the group consisting of α-pinene, β-pinene, limonene, dipentene, etc., as the most abundant monomer component, preferably at least 50 mol %, and may be hydrogenated or modified. Specific examples of terpene resins include polyterpene resins containing only one or more of the terpene compounds as monomer components; aromatic-modified terpene resins containing the terpene compound and an aromatic compound as monomer components; and terpene phenolic resins containing the terpene compound and a phenolic compound as monomer components. Examples of aromatic compounds that serve as monomer components for aromatic-modified terpene resins include at least one selected from the group consisting of styrene, α-methylstyrene, vinyltoluene, divinyltoluene, etc. Examples of phenolic compounds that serve as monomer components for terpene phenolic resins include at least one selected from the group consisting of phenol, bisphenol A, cresol, xylenol, etc. These resins may be used alone or in combination.

[0132] Rosin-based resin The rosin-based resin refers to a resin containing at least one rosin acid compound selected from the group consisting of abietic acid, neoabietic acid, palustric acid, isopimaric acid, etc., preferably as the monomer component with the largest content, more preferably at least 50 mol %, and may be hydrogenated or modified. The rosin-based resin is not particularly limited, but examples include natural rosin resin and rosin-modified resins obtained by modifying rosin by hydrogenation, disproportionation, dimerization, esterification, etc. Such resins may be used alone or in combination of two or more.

[0133] Phenolic resin The phenolic resin refers to a resin containing a phenolic compound such as phenol or cresol as the monomer component with the largest content, preferably 50 mol% or more. Examples of the phenolic resin include, but are not limited to, phenol-formaldehyde resin, alkylphenol-formaldehyde resin, alkylphenol-acetylene resin, and oil-modified phenol-formaldehyde resin. These resins may be used alone or in combination of two or more.

[0134] From the viewpoint of grip performance, the softening point of the resin is preferably 60° C. or higher, more preferably 75° C. or higher, and even more preferably 90° C. or higher. From the viewpoint of processability and improving the dispersibility of the rubber component and the filler, the softening point is preferably 150° C. or lower, more preferably 120° C. or lower, and even more preferably 100° C. or lower. The softening point of the resin is measured by the above-mentioned measurement method.

[0135] When a resin is contained, the content per 100 parts by mass of the rubber component is preferably more than 1 part by mass, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more. On the other hand, from the viewpoint of suppressing heat buildup, the content is preferably less than 15 parts by mass, more preferably less than 10 parts by mass, and even more preferably less than 5 parts by mass.

[0136] <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.

[0137] 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, oils with a low content of polycyclic aromatic compounds (PCA) can also be used as an environmentally friendly solution. Examples of low PCA oils include MES, TDAE, and heavy naphthenic oil. One type of vegetable oil may be used alone, or two or more types may be used in combination.

[0138] As used herein, 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 and the like. Vegetable oils may be liquid or solid at 25°C. One vegetable oil may be used alone, or two or more may be used in combination.

[0139] 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 esterified with 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. The acylglycerol may be liquid or solid at 25°C.

[0140] 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 25°C for 24 hours, and after removing the rubber composition, the 1 When 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.

[0141] 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.

[0142] Among these, it is desirable that the fatty acid contains a fatty acid with few double bonds, i.e., saturated fatty acid or monounsaturated fatty acid, and oleic acid is preferred. As a vegetable oil containing such a fatty acid, for example, vegetable oil containing saturated fatty acid or monounsaturated fatty acid may be used, or vegetable oil modified by ester exchange or the like may be used. Furthermore, in order to produce vegetable oil containing such a fatty acid, plants may be improved by breeding, genetic modification, genome editing, or the like.

[0143] 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.

[0144] Examples of animal oils include fish oil, beef tallow, and oleyl alcohol derived from these.

[0145] The oil content per 100 parts by mass of the rubber component is preferably more than 3 parts by mass, more preferably more than 5 parts by mass, and even more preferably 10 parts by mass or more. The content is preferably less than 30 parts by mass, more preferably less than 20 parts by mass, and even more preferably 15 parts by mass or less, and even more preferably 10 parts by mass or less. The oil content includes the amount of oil contained in the rubber component as an extender oil and the amount of oil contained in other components such as sulfur.

[0146] <Liquid rubber> Liquid rubber is a polymer that is liquid at 25°C, and examples thereof include liquid diene polymers. Examples of liquid diene polymers include liquid styrene-butadiene copolymers (liquid SBR), liquid butadiene polymers (liquid BR), liquid isoprene polymers (liquid IR), and liquid styrene-isoprene copolymers (liquid SIR). The liquid diene polymers preferably have a polystyrene-equivalent number average molecular weight (Mn) measured by gel permeation chromatography (GPC) of more than 1,000, more preferably more than 3,000, while the Mn is preferably less than 100,000, more preferably less than 15,000. The Mn of the liquid rubber is a polystyrene-equivalent value measured by gel permeation chromatography (GPC). Examples of liquid diene polymers that can be used include products from Sartomer Corporation and Kuraray Co., Ltd. Liquid rubbers may be used alone or in combination of two or more.

[0147] <Ester-based plasticizers> 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.

[0148] <Plasticizer content> When a plasticizer is contained, the content per 100 parts by mass of the rubber component is preferably less than 30 parts by mass, more preferably less than 20 parts by mass, even more preferably 15 parts by mass or less, and still more preferably 13 parts by mass or less. The content is preferably more than 5 parts by mass, more preferably more than 7 parts by mass, and even more preferably 10 parts by mass or more.

[0149] (Compatibilizer) Compatibilizers are used to reduce the repulsion energy at the interface between a polymer and a filler or between different polymers, thereby promoting intermixing. There are no particular limitations on the compatibilizer, and any of those conventionally used in the tire industry can be used. Specific examples of compatibilizers include non-reactive compatibilizers such as ethylene-propylene-styrene copolymers, styrene-ethylene-butadiene block copolymers, styrene-methyl methacrylate block copolymers, ethylene-styrene graft copolymers, chlorinated polyethylene, mixtures of aromatic hydrocarbon resins and aliphatic hydrocarbon resins, and metal soaps of unsaturated fatty acids, as well as reactive compatibilizers such as maleic anhydride grafted polypropylene, styrene-maleic anhydride copolymers, ethylene-glycidyl methacrylate copolymers, and styrene graft copolymers onto ethylene-glycidyl methacrylate copolymers. Among these, ethylene-propylene-styrene copolymers are preferred. Compatibilizers may be used alone or in combination of two or more.

[0150] The content of the compatibilizer is not particularly limited, but in consideration of air barrier properties, it is, for example, preferably more than 3 parts by mass, more preferably more than 4 parts by mass, and even more preferably 5 parts by mass or more per 100 parts by mass of the rubber component, while the content is preferably less than 15 parts by mass, more preferably less than 12 parts by mass, and even more preferably less than 10 parts by mass.

[0151] (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. Examples of processing aids that can be used include those commercially available from Schill + Seilacher, Performance Additives, etc. One type of processing aid may be used alone, or two or more types may be used in combination.

[0152] 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 part 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.

[0153] (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. The vulcanized rubber particles are not particularly limited, and may be unmodified vulcanized rubber particles or modified vulcanized rubber particles. Commercially available vulcanized rubber products include products from Lehigh and Muraoka Rubber Industries Co., Ltd. One type of vulcanized rubber particle may be used alone, or two or more types may be used in combination.

[0154] (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. Among these, mineral waxes are 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 this embodiment does not contain stearic acid. Waxes commercially available from, for example, Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., Paramelt Co., Ltd., etc. can be used. One type of wax may be used alone, or two or more types may be used in combination.

[0155] When the wax is contained, the amount thereof per 100 parts by mass of the rubber component is preferably more than 0.3 parts by mass, more preferably more than 0.7 parts by mass, and even more preferably more than 1.0 part by mass, while the amount is preferably less than 4.0 parts by mass, more preferably less than 3.0 parts by mass, and even more preferably less than 2.5 parts by mass.

[0156] (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 0.7 parts by mass, and even more preferably 1.0 part by mass or more from the viewpoint of processability, while the content is preferably less than 10 parts by mass, more preferably less than 5 parts by mass, and even more preferably less than 3 parts by mass from the viewpoint of vulcanization rate.

[0157] (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 0.7 parts by mass, and even more preferably 1 part by mass or more, from the viewpoint of processability, while the content is preferably less than 10 parts by mass, more preferably less than 5 parts by mass, and even more preferably less than 3 parts by mass, from the viewpoint of abrasion resistance.

[0158] (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), and N,N'-ditolyl-p-phenylenediamine. p-phenylenediamine-based antioxidants such as diphenyl ether diphenyl ether (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.

[0159] When an antioxidant 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 0.8 parts by mass, and even more preferably more than 1.0 part by mass, while the content is preferably less than 7.0 parts by mass, more preferably less than 5.0 parts by mass, and even more preferably 3.0 parts by mass or less.

[0160] (Crosslinking agent) The crosslinking between polymers in the crosslinked rubber is not limited to crosslinking involving the boron atom-containing group, but may also include other crosslinking such as sulfur crosslinking. In this case, a desired crosslinking agent and vulcanization accelerator can be appropriately blended. The crosslinking agent is not particularly limited, and known crosslinking agents can be used, such as organic peroxides, sulfur-based vulcanizing agents, resin vulcanizing agents, and metal oxides such as magnesium oxide. Of these, sulfur-based vulcanizing agents are preferred. Examples of sulfur-based vulcanizing agents that can be used include sulfur and sulfur donors such as morpholine disulfide. Of these, sulfur is preferred. One or more crosslinking agents can be used in combination.

[0161] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur (oil-treated sulfur, special sulfur treated with a dispersant, masterbatch-type sulfur, etc.), and insoluble sulfur (oil-treated insoluble sulfur, etc.), all of which are preferably used. Among these, powdered sulfur is preferred. Examples of sulfur that can be used include those manufactured and sold by Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexis Corporation, Nippon Kanritsu Kogyo Co., Ltd., Hosoi Chemical Industry Co., Ltd., etc.

[0162] Known organic crosslinking agents can also be used as the crosslinking agent. 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.

[0163] When a crosslinking agent is contained, the content per 100 parts by mass of the rubber component is preferably more than 0.4 parts by mass, more preferably 0.5 parts by mass or more, and even more preferably 1.0 part by mass or more. On the other hand, the content is preferably less than 6.0 parts by mass, more preferably less than 4.0 parts by mass, and even more preferably less than 2.0 parts by mass. When the content of the crosslinking agent is within the above range, an appropriate reinforcing effect tends to be obtained. Note that when the crosslinking agent is a vulcanizing agent and the vulcanizing agent contains components other than sulfur, such as oil-treated sulfur, the content of the crosslinking agent refers to the content of the sulfur component itself.

[0164] (Vulcanization accelerator) The vulcanization accelerator is not particularly limited, and known vulcanization accelerators can be used. Examples include sulfenamide-based, thiazole-based, thiuram-based, thiourea-based, guanidine-based, dithiocarbamic acid-based, aldehyde-amine-based or aldehyde-ammonia-based, imidazoline-based, and xanthate-based vulcanization accelerators. Among these, thiazole-based, sulfenamide-based, thiuram-based, and guanidine-based accelerators are preferred, and thiazole-based and sulfenamide-based accelerators are more preferred. Examples of vulcanization accelerators that can be used include those manufactured and sold by Ouchi Shinko Chemical Industry Co., Ltd., Sanshin Chemical Industry Co., Ltd., etc. One vulcanization accelerator may be used alone, or two or more vulcanization accelerators may be used in combination.

[0165] Examples of sulfenamide vulcanization accelerators include N-tert-butyl-2-benzothiazolyl sulfenamide (TBBS), N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS), and N,N'-dicyclohexyl-2-benzothiazolyl sulfenamide (DZ). Examples of thiazole vulcanization accelerators include di-2-benzothiazolyl disulfide. Examples of thiuram vulcanization accelerators include tetramethylthiuram monosulfide, tetramethylthiuram disulfide, and tetrabenzylthiuram disulfide (TBzTD). Examples of guanidine vulcanization accelerators include 1,3-diphenylguanidine (DPG), di-orthotolylguanidine, and orthotolylbiguanidine. Of these, a combination of a sulfenamide vulcanization accelerator and a guanidine vulcanization accelerator is preferred, or a combination of these two vulcanization accelerators with a thiazole vulcanization accelerator is also preferred.

[0166] The content of the vulcanization accelerator per 100 parts by mass of the rubber component is preferably more than 1.0 part by mass, more preferably more than 0.5 part by mass, and even more preferably 1.8 parts by mass or more. On the other hand, the content is preferably less than 6.0 parts by mass, more preferably less than 5.0 parts by mass, and even more preferably 4.0 parts by mass or less. When the content of the vulcanization accelerator is within the above range, breaking strength and elongation tend to be ensured.

[0167] <Various materials containing carbon atoms> In this specification, various materials containing carbon atoms (for example, rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from atmospheric carbon dioxide. As a method for obtaining such 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.

[0168] <Applications of cross-linked rubber> The crosslinked rubber can be used as a crosslinked rubber constituting various tire components such as a cap tread, a base tread, a sidewall, a clinch apex, a wing, and an inner liner.

[0169] <When crosslinked rubber constitutes the inner liner> When the crosslinked rubber constitutes the inner liner, the rubber component preferably contains a butyl rubber. The above explanations can be applied to the components other than the rubber component.

[0170] In this case, the rubber component may contain a rubber component other than butyl-based rubber. Examples of rubber components other than butyl-based rubber include diene-based rubbers such as isoprene-based rubber (IR rubber), styrene-butadiene rubber (SBR), and butadiene rubber (BR). These diene-based rubbers may be specifically modified diene-based rubbers. The non-diene-based rubbers and rubber components synthesized from recycled or biomass-derived raw materials can also be used. The butyl-based rubbers, rubber components other than butyl-based rubbers, diene-based rubbers, and non-diene rubbers may each be used alone or in combination of two or more.

[0171] Examples of butyl rubbers include butyl rubber (IIR), and halogenated butyl rubbers such as brominated butyl rubber (Br-IIR) and chlorinated butyl rubber (Cl-IIR). Among these, halogenated butyl rubber is preferred, and brominated butyl rubber and chlorinated butyl rubber are more preferred, as they can improve sheet processability and air barrier properties in a balanced manner. One or more types of butyl rubber can be used.

[0172] As the butyl-based rubber, for example, products of ExxonMobil Corporation, ENEOS Materials Corporation, Arlanxeo, JSR Corporation, Japan Butyl Co., Ltd., etc. can be used.

[0173] From the viewpoint of air permeation resistance and heat resistance, the content of the butyl rubber in the rubber component is preferably more than 70% by mass, more preferably more than 80% by mass, even more preferably more than 90% by mass, and may be 100% by mass.

[0174] [Manufacturing method] The tire according to this embodiment can be manufactured by a known method.

[0175] <Production of Rubber Composition> A rubber composition containing a rubber component and a crosslinking agent before crosslinking can be produced by a known method. For example, it can be produced by kneading the components using a rubber kneading device such as an open roll or an internal kneader (e.g., a Banbury mixer or kneader). 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 can be divided into multiple processes as desired. The kneading conditions are not particularly limited, but examples include a method in which the base kneading process involves kneading for 3 to 10 minutes at a discharge temperature of 130 to 170°C, and a method in which the final kneading process involves kneading for 1 to 5 minutes at 50 to 110°C.

[0176] <Tire manufacturing> The rubber compositions obtained above are extruded in the uncrosslinked state to form the desired rubber components. The rubber components are, for example, at least one selected from the group consisting of cap treads, inner liners, sidewalls, clinch apexes, wings, and the like. The rubber components thus obtained can be molded together with other tire components in a tire building machine using a conventional method to form an uncrosslinked tire. The tire of this embodiment can be manufactured by heating and pressurizing the uncrosslinked tire in a vulcanizer. The crosslinking conditions are not particularly limited, and examples include a method of crosslinking at 150 to 200°C for 5 to 30 minutes.

[0177] [Application] In this specification, the term "tire" refers to a tire that 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. In this specification, the term "tire" refers to all-season tires, summer tires, and winter tires such as studless tires. [Example]

[0178] Below, examples (working examples) that are considered preferable for carrying out the present invention are shown, but the scope of the present invention is not limited to the working examples. According to each table, crosslinked rubbers constituting cap treads obtained using the various chemicals shown below, and tires having the tire structure were examined, and the results calculated based on the evaluation methods below are shown at the bottom of each table.

[0179] [Various medicines] The various chemicals used in the examples and comparative examples are listed below. IR rubber: NR (TSR20) SBR: SBR produced by Production Example 1 below (styrene content: 25% by mass, vinyl content: 59% by mole, Tg: -22°C, Mw: 350,000, non-oil extended) BR: ASAPRENE N103 (cis content: 38 mol%, Mw: 550,000, available from Asahi Kasei Corporation) Specific modified diene rubber 1: Specific modified NR produced by Production Example 2 below Specific modified diene rubber 2: Specific modified SBR produced by Production Example 3 below Specific modified diene rubber 3: Specific modified BR produced by Production Example 4 below BDB: Benzene-1,4-diboronic acid diester compound (molecular weight 310.01, total boron atom weight 21.62) represented by the following chemical formula [ka] CB (carbon black): Diablack I (N220, N2SA: 114m) manufactured by Mitsubishi Chemical Corporation 2 / g, average primary particle diameter: 22nm) Silica: Ultrasil VN3 (N2SA: 175 ml) manufactured by Evonik Degussa 2 / g, average primary particle diameter: 18nm) Coupling agent (silane coupling agent): Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa Resin: Tosoh Corporation's Petrotack 90 (C5 / C9 resin, softening point: 95°C) Oil: Diana Process NH-70S manufactured by Idemitsu Kosan Co., Ltd. Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Antioxidant: Nocrac 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Stearic acid: Camellia stearic acid beads manufactured by NOF Corporation Wax: Ozoace 0355 (paraffin wax) manufactured by Nippon Seiro Co., Ltd. Radical initiator: 2,2'-azobis(isobutyronitrile) Sulfur: 5% oil-treated powder sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. Vulcanization accelerator 1: Noccelaer D (1,3-diphenylguanidine (DPG)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 2: Noccela CZ (N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 3: Noccela DM-P (DM) (di-2-benzothiazolyl disulfide (MBTS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 4: Sancerer NS-G (N-(tert-butyl)-2-benzothiazole sulfenamide (TBBS)) manufactured by Sanshin Chemical Industry Co., Ltd.

[0180] Manufacturing Example 1: Manufacturing of SBR Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene are charged into a nitrogen-purged autoclave reactor. The ratio of styrene to 1,3-butadiene is adjusted so that the styrene content is 25% by mass. After adjusting the temperature of the reactor contents to 20°C, n-butyllithium is added to initiate polymerization. Polymerization occurs under adiabatic conditions, reaching a maximum temperature of 80°C. After confirming the formation of a polymer with a Mw of 350,000 by GPC, the polymerization solution is poured into 4 L of ethanol and the precipitate is recovered. The resulting precipitate is blown dry and then vacuum dried at 80°C / 10 Pa or less until the loss on drying is 0.1%, yielding SBR.

[0181] Production Example 2: Production of specific modified diene rubber 1 100 parts by mass of the NR (TSR20) and the borane-pyridine complex were mixed for 5 minutes in a mixer set at 90°C to synthesize isoprene rubber modified with the borane-pyridine complex, i.e., specially modified NR. The boron content of the specially modified NR was 0.1 parts by mass.

[0182] Production Example 3: Production of specific modified diene rubber 2 A styrene-butadiene rubber modified with the borane-pyridine complex, i.e., a specially modified SBR, is synthesized by mixing 100 parts by mass of the SBR obtained in Production Example 1 above with a borane-pyridine complex for 5 minutes in a mixer set to 90°C. The boron content of the specially modified SBR is 0.1 parts by mass.

[0183] Production Example 4: Production of specific modified diene rubber 3 100 parts by mass of the BR (ASAPRENE N103) and the borane-pyridine complex were mixed for 5 minutes in a mixer set to 90°C to synthesize a butadiene rubber modified with the borane-pyridine complex, i.e., a specially modified BR. The boron content of the specially modified BR was 0.1 parts by mass.

[0184] [Examples and Comparative Examples] Tires were manufactured according to the tire structure and compounding recipes shown in each table. First, using a 1.7 L closed-type Banbury mixer, all chemicals except sulfur and vulcanization accelerators were mixed for 1 to 10 minutes until the discharge temperature reached 150 to 160°C, yielding a kneaded mixture. Next, using a two-screw open roll, sulfur and vulcanization accelerators were added to the resulting mixture, which was then mixed for 4 minutes until the temperature reached 105°C, yielding an unvulcanized rubber composition. The resulting unvulcanized rubber composition was extruded into the shape of a cap tread using an extruder equipped with a predetermined die, and then bonded together with other tire components to produce an unvulcanized tire. The resulting unvulcanized tire was press-vulcanized for 12 minutes at 170°C to produce each test tire (tire size: 195 / 65R15). Note that the thickness of the base tread was kept constant regardless of the thickness of the cap tread.

[0185] [evaluation] The results of measurements for each test tire by the following methods are recorded in the corresponding columns of the table below. Unless otherwise specified, each test tire is used after being brought into normal condition.

[0186] <Low fuel consumption performance> For each test tire, a rolling resistance tester is used to measure the rolling resistance coefficient (RRC) when the tire runs on a drum at a speed of 80 km / h under the following conditions. The results are expressed as an index, with the reference comparative example being set at 100. The higher the index, the lower the rolling resistance of the tire. Rim size: 15 x 6.5J Internal pressure: 210kPa Load: 4.82kN

[0187] [Table 1]

[0188] [Table 2]

[0189] [Embodiment] Examples of embodiments of the present invention are given below.

[0190] [1] A tire having at least one rubber member composed of a rubber component containing an isoprene-based rubber and a rubber containing a butadiene unit, silica, and a crosslinked rubber containing a crosslinking agent, The crosslinked rubber has a boron atom-containing group, The content (mass%) of isoprene-based rubber in the rubber component is A IR The content (mass%) of the rubber containing the butadiene unit is A BD When the thickness (mm) of the rubber member is T, the tire satisfies the following formula, and preferably the value of the right side of formula (1) is 75, more preferably 80, even more preferably 85, even more preferably 90, and even more preferably 95, and preferably the value of the right side of formula (2) is 11.0. (1) A IR +A BD >70 (2)(A IR +A BD ) / T>10.0 (However, A IR >10, A BD >10) [2] The tire according to the above [1], wherein the value of the right side of the formula (2) is 12.0, preferably 13.0. [3] The tire according to the above [1], wherein the value of the right side of formula (2) is 14.0. [4] The tire according to any one of [1] to [3] above, wherein the boron content per 100 parts by mass of the rubber component is 0.05 parts by mass or more, preferably 0.07 parts by mass or more, more preferably 0.09 parts by mass or more, even more preferably 0.3 parts by mass or more, even more preferably 0.5 parts by mass or more, even more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more. [5] The tire according to any one of the above [1] to [4], wherein the rubber containing butadiene units contains styrene butadiene rubber. [6] The tire according to any one of the above [1] to [4], wherein the rubber containing butadiene units contains a styrene butadiene rubber and a butadiene rubber. [7] The tire according to [5] or [6] above, wherein the content of the styrene-butadiene rubber in the rubber component is 80% by mass or more, preferably 85% by mass or more. [8] The crosslinked rubber contains a plasticizer, The tire according to any one of the above [1] to [7], wherein the content of the plasticizer is 15 parts by mass or less, preferably 13 parts by mass or less, per 100 parts by mass of the rubber component. [9] The crosslinked rubber contains a plasticizer, The tire according to any one of the above [1] to [8], wherein the plasticizer contains a resin.

[10] The tire according to any one of the above [1] to [9], wherein at least one rubber selected from the group consisting of the isoprene-based rubber and the rubber containing butadiene units is a modified rubber modified with a complex of a nitrogen-containing aromatic compound and a boron compound having a BH bond.

[11] The tire according to

[10] above, wherein the nitrogen-containing aromatic compound is at least one selected from the group consisting of pyridine, quinoxaline, pyrrole, pyrazine, pyrimidine, pyridazine, thiazole, oxazole, imidazole, pyrazole, isoxazole, isothiazole, triazole, furazan, oxadithiazole, thiadiazole, dioxazole, and dithiazole.

[12] The tire according to any one of the above [1] to

[11] , wherein the crosslinked rubber has crosslinked sites bonded via boron-oxygen bonds.

[13] The tire according to

[12] above, wherein the crosslinking site includes a group having a diboronic acid ester skeleton unit.

[14] The tire according to any one of the above [1] to

[13] , wherein the rubber member is one selected from a cap tread, a base tread, a sidewall, a clinch apex, a wing, and an inner liner.

[15] The tire according to

[14] above, wherein the rubber member is a cap tread. [Explanation of symbols]

[0191] 1 Cap Tread 3 Inner liner rubber 4 Sidewall 5 Clinch Apex 6 Wing T1 Cap tread thickness T3 Inner liner thickness T4 Sidewall Thickness T5 Clinch Apex Thickness T6 Wing Thickness P1: The point where the sidewall and clinch apex meet on the outer surface of the tire. L1 Normal to the main body of the carcass P2 The point where the tread contour line on the outside in the tire width direction intersects with the sidewall contour line on the outside in the tire radial direction L2 Normal to outer tire surface CL Tire centerline R rim

Claims

1. A tire having at least one rubber member composed of a rubber component containing an isoprene-based rubber and a rubber containing a butadiene unit, and a crosslinked rubber containing silica and a crosslinking agent, The crosslinked rubber has a boron atom-containing group, The content (mass%) of the isoprene-based rubber in the rubber component is A IR The content (mass%) of the rubber containing the butadiene unit is A BD When the thickness (mm) of the rubber member is T, a tire satisfies the following formula: (1) A IR +A BD >70 (2)(A IR +A BD ) / T>10.0 (However, A IR >10, A BD >10)

2. The tire according to claim 1, wherein the value of the right side of formula (2) is 12.

0.

3. The tire according to claim 1, wherein the value of the right side of formula (2) is 14.

0.

4. The tire according to claim 1, wherein the boron content per 100 parts by mass of the rubber component is 0.05 parts by mass or more.

5. 5. The tire of claim 1 or 4, wherein the rubber containing butadiene units comprises a styrene butadiene rubber.

6. The tire according to claim 1 or 4, wherein the rubber containing butadiene units comprises a styrene butadiene rubber and a butadiene rubber.

7. The tire according to claim 5, wherein the content of the styrene-butadiene rubber in the rubber component is 80% by mass or more.

8. the crosslinked rubber contains a plasticizer, The tire according to claim 1 or 4, wherein the content of the plasticizer is 15 parts by mass or less per 100 parts by mass of the rubber component.

9. the crosslinked rubber contains a plasticizer, The tire of claim 1 or 4, wherein the plasticizer comprises a resin.

10. The tire according to claim 1 or 4, wherein at least one rubber selected from the group consisting of the isoprene-based rubber and the rubber containing a butadiene unit is a modified rubber modified with a complex of a nitrogen-containing aromatic compound and a boron compound having a B—H bond.

11. 11. The tire of claim 10, wherein the nitrogen-containing aromatic compound is at least one selected from the group consisting of pyridine, quinoxaline, pyrrole, pyrazine, pyrimidine, pyridazine, thiazole, oxazole, imidazole, pyrazole, isoxazole, isothiazole, triazole, furazan, oxadithiazole, thiadiazole, dioxazole, and dithiazole.

12. The tire according to claim 1 or 4, wherein the crosslinked rubber has crosslinking sites bonded via boron-oxygen bonds.

13. The tire of claim 12 , wherein the crosslinking sites include groups having diboronic ester backbone units.

14. 5. The tire according to claim 1, wherein the rubber member is one selected from the group consisting of a cap tread, a base tread, a sidewall, a clinch apex, a wing, and an inner liner.

15. 15. The tire of claim 14, wherein the rubber element is a cap tread.

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