tire

Abstract

To provide a tire having improved durability.SOLUTION: A tire comprising at least one rubber member composed of a crosslinked rubber comprising a rubber ingredient and a crosslinking agent, wherein the crosslinked rubber comprises a boron atom-containing group, and the rubber ingredient comprises a polymer comprising a - CH = CH - unit, a - CH2 - CH (- CH = CH2) - unit and a - CH2 - CHPh - unit (wherein Ph is phenyl) as a repeating unit, when a content of the polymer in the rubber components is 50% by mass or more, a boron content (parts by mass) in the crosslinked rubber with respect to 100 parts by mass of the rubber components is B, a content (parts by mass) of a - CH2 - CH (- CH = CH2) - unit in the rubber components with respect to 100 parts by mass of the rubber components is Y, and a thickness (mm) of the rubber member is T, the following relational expressions (1) and (2) are simultaneously satisfied: (1)Y<6.0(2)B / (Y*T)*104>1 SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] From the perspectives of environmental issues and resource conservation, the reuse of tires is being considered, and as part of this effort, crosslinked rubber, which is easier to reuse than vulcanized rubber, is being developed. Patent Document 1 describes an elastomer crosslinked with a diboronic acid ester compound, which is said to be easy to decrosslink and can be used in tires, seismic isolation rubber, and various hoses. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2023 / 013333 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a tire having improved durability, which includes at least one rubber component made of a crosslinked rubber containing a boron atom-containing group. [Means for solving the problem]

[0005] The present invention relates to the following tire. A tire having at least one rubber member made of a crosslinked rubber containing a rubber component and a crosslinking agent, the crosslinked rubber contains a boron atom-containing group, the rubber component comprises a polymer including, as repeating units, a -CH=CH- unit, a -CH2-CH(-CH=CH2)- unit, and a -CH2-CHPh- unit (wherein Ph represents a phenyl group); The content of the polymer in the rubber component is 50% by mass or more, A tire that simultaneously satisfies the following relational formula (1) and formula (2), where B is the boron content (parts by mass) in the crosslinked rubber relative to 100 parts by mass of the rubber component, Y is the content (parts by mass) of -CH2-CH(-CH=CH2)- units in the rubber component relative to 100 parts by mass of the rubber component, and T is the thickness (mm) of the rubber member. (1) Y<6.0 (2) B / (Y×T)×10 4 >1 [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a tire having improved durability, which includes at least one rubber member made of a crosslinked rubber containing a boron atom-containing group. [Brief explanation of the drawings]

[0007] [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

[0008] The tire of this embodiment is a tire having at least one rubber member made of a cross-linked rubber containing a rubber component and a cross-linking agent, wherein the cross-linked rubber contains a boron atom-containing group, and the rubber component contains a polymer containing -CH=CH- units, -CH2-CH(-CH=CH2)- units, and -CH2-CHPh- units (where Ph represents a phenyl group) as repeating units, and the content of the polymer in the rubber component is 50% by mass or more, and the tire simultaneously satisfies the following relational formulas (1) and (2), where B is the boron content (parts by mass) in the cross-linked rubber per 100 parts by mass of the rubber component, Y is the content (parts by mass) of -CH2-CH(-CH=CH2)- units in the rubber component per 100 parts by mass of the rubber component, and T is the thickness (mm) of the rubber member. (1) Y<6.0 (2) B / (Y×T)×10 4 >1

[0009] While not intending to be bound by theory, the mechanism by which durability is improved in a tire according to the present embodiment, which includes a rubber component made of a crosslinked rubber containing a boron atom-containing group, is believed to be as follows. Specifically, (a) by incorporating 50% by mass or more of a polymer having a predetermined repeating unit into 100% by mass of the rubber component, sufficient crosslinking structures are formed between the double bonds of the rubber component and the boron atom-containing groups, which is believed to contribute to tire durability. Furthermore, (b) when the rubber component contains a large amount of -CH2-CH(-CH=CH2)- units, gelation occurs during heat molding, affecting tire durability. However, by limiting the amount of -CH2-CH(-CH=CH2)- units to less than 5 parts by mass, gelation during heat molding is suppressed, which is believed to contribute to improved tire durability. Furthermore, (c) by maintaining the ratio of boron content to vinyl content at a certain value or greater relative to the thickness of the component, a sufficient crosslinking structure is formed, improving reinforcement. These (a) to (c) are believed to work together to achieve the excellent effect of improving tire durability.

[0010] Furthermore, the crosslinked rubber crosslinked by the boron atom-containing group can be easily decrosslinked by a transesterification reaction, and therefore the tire according to the present embodiment can be reused more easily than a tire manufactured using a normal vulcanized rubber.

[0011] The thickness T of the rubber member made of the crosslinked rubber is preferably 5 mm or less.

[0012] The rubber component preferably further contains an isoprene-based rubber.

[0013] The right side of formula (1) is preferably 5.0, and more preferably 4.2.

[0014] Tires that satisfy stricter conditions of formula (1) are considered to have even greater durability.

[0015] The right side of formula (2) is preferably 100. The value of the left side of formula (2) is preferably less than 5,000.

[0016] Tires that satisfy stricter conditions of formula (2) are considered to have even greater durability.

[0017] Preferably, the polymer further comprises -CH2-CH2-CH2-CH2- units and / or -CH2-CH(-CH2-CH3)- units.

[0018] The crosslinked rubber preferably has crosslinking sites bonded via boron-oxygen bonds.

[0019] The crosslinking site preferably contains a group having a diboronic acid ester skeleton unit.

[0020] The polymer is preferably a modified polymer modified with a complex of a nitrogen-containing aromatic compound and a borane compound.

[0021] It is believed that modified polymers modified with a complex of a nitrogen-containing aromatic compound and a borane compound strongly interact with fillers such as carbon black and silica, thereby improving reinforcing strength and contributing to improved durability. In addition, modified polymers modified with a complex of a nitrogen-containing aromatic compound and a borane compound are thought to form crosslinked sites via boron atoms by bonding or reacting with each other depending on the type of modifying group, which is believed to contribute to improved reinforcing strength and durability.

[0022] 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.

[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.

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

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

[0030] "Maximum load capacity W L " is calculated using the following formula: "V" is the virtual volume of the tire (mm 3 ), "Dt" is the outer diameter (mm) of the tire in its normal state, "Ht" is the tire's cross-sectional height (mm) in the 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] "Hydrogenated styrene butadiene rubber" refers to a copolymer of styrene and 1,3-butadiene, i.e., a hydrogenated product of styrene butadiene rubber (SBR). Hydrogenated styrene butadiene rubber also includes hydrogenated products of modified styrene butadiene rubber (modified SBR) modified by the method described below. The hydrogenation rate (hydrogenation rate) of hydrogenated styrene butadiene rubber is as follows: 1 It is a value calculated from the integral values ​​of the peaks derived from double bonds in H-NMR according to the following formula: In this specification, the hydrogenation rate refers to the hydrogenation rate of double bonds. (Hydrogenation rate [%])={(AB) / A}×100 A: Integrated value of the double bond peak before hydrogenation B: Integrated value of the double bond peak after hydrogenation

[0033] "Thickness of rubber component" is the maximum thickness (mm) of the rubber component in question in the 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 piece, and measuring the space between the beads of the tire piece while maintaining the regular rim width. The thickness is the average of the thicknesses measured at five points while rotating the tire 72 degrees each time.

[0034] When the thickness of a rubber component is substantially uniform in the cross section of the tire, the thickness at a predetermined location is taken as the thickness of the rubber component. That is, (1) for components whose radial thickness can be recognized on the tire centerline, the thickness of the component is taken as the thickness of the component. (2) for rubber components whose thickness cannot be recognized as described in (1), the thickness at the tire's maximum width position in the tire rotational axis direction is taken as the thickness of the component. Examples of rubber components in (1) include cap tread, base tread, inner liner, etc. Furthermore, examples of rubber components in (2) include sidewalls, etc.

[0035] On the other hand, if the thickness of a rubber member varies in the cross section of the tire, the thickness is determined taking into consideration a normal thickness recognition method for that rubber member, such as a clinch apex, a wing, etc.

[0036] 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.

[0037] The "base 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 T2 in Figure 1.

[0038] 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.

[0039] 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.

[0040] 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 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 measured along the normal L1.

[0041] "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.

[0042] "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.

[0043] <Measurement method> "Styrene content" and "-CH2-CHPh- unit content" are measured by pyrolysis gas chromatography and NMR measurement ( 1 H-NMR and 13The 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.

[0044] "Vinyl content (amount of 1,2-bonded butadiene units)" and "-CH2-CH(-CH=CH2)- unit content" are measured by pyrolysis gas chromatography and 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.

[0045] "Cis content (cis-1,4-bonded butadiene unit content)" and "-CH=CH- unit content" are measured by infrared absorption spectroscopy and 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," there is a true value for the "cis content" that is independent of the measurement method, so it is preferable to use a measurement method with as high accuracy as possible.

[0046] The "ash content of recycled carbon black" is measured by the thermogravimetric method of JIS K 6226-2:2003.

[0047] The "average primary particle size of carbon black" is a value determined by photographing particles with a transmission or scanning electron microscope and arithmetically averaging the particle sizes of 400 particles. If the particle shape is spherical, the particle size is the diameter of the sphere; if the particle shape is non-spherical, the particle size is calculated from the microscope image as the circle-equivalent diameter (positive square root of {4 x (particle area) / π}). This applies to carbon black, including recycled carbon black.

[0048] The "nitrogen adsorption specific surface area (N2SA) of carbon black" is measured in accordance with JIS K 6217-2:2017.

[0049] The "nitrogen adsorption specific surface area (N2SA) of silica" is measured by the BET method in accordance with ASTM D3037-93.

[0050] 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.

[0051] 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.

[0052] <Tires> The tire according to the present embodiment will be described below with reference to the drawings as appropriate, although the drawings are merely examples for the purpose of explanation.

[0053] The tire according to the present embodiment is a tire having at least one rubber member made of a cross-linked rubber containing a rubber component and a cross-linking agent, wherein the cross-linked rubber contains a boron atom-containing group, and the rubber component contains a polymer containing -CH=CH- units, -CH2-CH(-CH=CH2)- units, and -CH2-CHPh- units (where Ph represents a phenyl group) as repeating units, and the content of the polymer in the rubber component is 50% by mass or more, and the tire simultaneously satisfies the following relational formulas (1) and (2), where B is the boron content (parts by mass) in the cross-linked rubber per 100 parts by mass of the rubber component, Y is the content (parts by mass) of -CH2-CH(-CH=CH2)- units in the rubber component per 100 parts by mass of the rubber component, and T is the thickness (mm) of the rubber member. (1) Y<6.0 (2) B / (Y×T)×10 4 >1

[0054] The rubber member made of a predetermined crosslinked rubber is not particularly limited, and various rubber members can be mentioned, specifically, a cap tread, a base tread, a sidewall, a clinch apex, a wing, an inner liner, etc.

[0055] 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, a base tread 2, an inner liner 3, a sidewall 4, a clinch apex 5, and a wing 6. The thickness of the cap tread 1 is indicated as T1, the thickness of the base tread 2 as T2, 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.

[0056] (Formula (1)) In formula (1), the value of the right side is preferably 5.0, more preferably 4.5, even more preferably 4.2, even more preferably 4.0, even more preferably 3.5, even more preferably 3.0, even more preferably 2.5, even more preferably 2.0, and even more preferably 1.5. On the other hand, from the viewpoint of durability, Y is preferably 0.10 or more, more preferably 0.20 or more, even more preferably 0.30 or more, even more preferably 0.50 or more, even more preferably 0.70 or more, even more preferably 0.75 or more, and even more preferably 0.80 or more.

[0057] (Formula (2)) The right side of formula (2) is preferably 10, more preferably 100, even more preferably 400, even more preferably 800, even more preferably 1000, even more preferably 2000, and even more preferably 4000. There is no particular upper limit to the left side of formula (2) from the viewpoint of the effects of the present invention, but it is usually 70,000, preferably 65,000, more preferably 60,000, and even more preferably 50,000. Formula (2) defines the relationship between the ratio (B / Y) of the boron content to the content of —CH—CH(—CH═CH)— units in the rubber component and the thickness T of the member, and satisfying this predetermined relationship allows for the production of a tire with improved durability.

[0058] 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 9 mm or less, and even more preferably 8 mm or less.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] <Crosslinked rubber> The crosslinked rubber constituting the rubber member will be described below. In this embodiment, the rubber member may be a cap tread, a base tread, a band, a belt, a carcass, an inner liner, a sidewall, a clinch apex, a wing, a topping rubber covering a cord, or any of a variety of other rubber members. Of these rubber members, one selected from the cap tread, the base tread, the sidewall, the clinch apex, the wing, and the inner liner is preferred, and among these, the cap tread, the sidewall, and the like are preferred as the rubber member.

[0065] The crosslinked rubber constituting these rubber members all contains a rubber component and a crosslinking agent, and the crosslinked rubber also contains a boron atom-containing group.

[0066] [Cross-linked rubber that makes up the cap tread] <Rubber component> The crosslinked rubber constituting the cap tread contains a polymer containing repeating units of -CH=CH-, -CH2-CH(-CH=CH2)-, and -CH2-CHPh- (where Ph represents a phenyl group) as a rubber component. Examples of such polymers include styrene-butadiene rubber (SBR) or a combination of SBR and butadiene rubber (BR). These polymers may also be modified with a borane complex (e.g., a complex of a nitrogen-containing aromatic compound and a borane compound). The polymer may contain rubber components other than SBR and BR. Examples of such rubber components include diene-based rubbers such as isoprene-based rubber (IR rubber), styrene-isoprene-butadiene rubber (SIBR), chloroprene rubber (CR), and acrylonitrile-butadiene rubber (NBR), as well as non-diene-based rubbers such as butyl rubber, ethylene-propylene rubber, polynorbornene rubber, silicone rubber, chlorinated polyethylene rubber, fluororubber (FKM), acrylic rubber (ACM), and hydrin rubber. These diene rubbers or non-diene rubbers may be used alone or in combination of two or more. Of these, diene rubbers are preferred. The rubber component may consist of SBR, or may consist only of SBR and BR, or may consist only of SBR, BR, and IR rubber. Furthermore, the polymer may further contain -CH-CH-CH-CH-CH- units and / or -CH-CH(-CH-CH)- units. In this case, such a polymer may include one containing hydrogenated SBR, as described below.

[0067] (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.

[0068] The styrene content of SBR is preferably more than 10% by mass, more preferably more than 15% by mass, and even more preferably more than 20% by mass. From the viewpoint of effectiveness, the styrene content is preferably less than 60% by mass, more preferably less than 55% by mass, and even more preferably less than 50% by mass. The styrene content and -CH-CHPh- unit content of SBR are values ​​measured by the above-mentioned method.

[0069] The vinyl content (amount of 1,2-bonded butadiene units) of SBR is preferably more than 10 mol%, more preferably more than 15 mol%, and even more preferably more than 17 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 and -CH-CH(-CH=CH)- unit content of SBR are values ​​measured by the above-mentioned method.

[0070] In the hydrogenated SBR, the hydrogenation rate of the SBR is preferably 40 mol% or more, more preferably 50 mol% or more, even more preferably 60 mol% or more, and particularly preferably 70 mol% or more. The hydrogenation rate is preferably 100 mol% or less, more preferably 99 mol% or less, even more preferably 98 mol% or less, and particularly preferably 90 mol% or less. The hydrogenation method and reaction conditions are not particularly limited, and hydrogenation may be carried out by a known method and under known conditions. Typically, hydrogenation is carried out at 20 to 150°C under a hydrogen pressure of 0.1 to 10 MPa in the presence of a hydrogenation catalyst. Other production methods and conditions are also not particularly limited, and for example, the contents described in International Publication No. 2016 / 039005 can be applied. In the hydrogenation reaction described in Production Example 3 below, the hydrogenation rate can be adjusted by adjusting reaction conditions such as the hydrogen gas supply pressure and reaction temperature.

[0071] The content of SBR in the rubber component is preferably more than 20% by mass, more preferably more than 30% by mass, even more preferably more than 40% by mass, and still more preferably 50% by mass or more, while the content may be, for example, less than 90% by mass, less than 80% by mass, or less than 70% by mass.

[0072] (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. Examples of modified BR include BR modified with a borane complex, which will be described later, and 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 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.

[0073] The cis content of BR is preferably more than 90 mol%, more preferably more than 93 mol%, even more preferably more than 95 mol%, and even more preferably 97 mol% or more. The cis content and —CH═CH— unit content of BR can be measured by the above-mentioned method.

[0074] As the BR, for example, products from UBE Corporation, JSR Corporation, Asahi Kasei Corporation, Nippon Zeon Corporation, etc. can be used.

[0075] The BR content in the rubber component is preferably more than 20% by mass, more preferably more than 30% by mass, even more preferably more than 400% by mass, and still more preferably 50% by mass or more, while the content is preferably less than 90% by mass, more preferably less than 80% by mass, and still more preferably less than 70% by mass.

[0076] (IR rubber) The rubber component may contain an IR rubber. Examples of the IR rubber include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. Examples of the NR include SIR20, RSS#3, TSR20, and SVR-L, which are commonly used in the tire industry. Examples of the IR include IR2200 and other commonly used rubbers. Examples of the modified NR include deproteinized natural rubber (DPNR) and highly purified natural rubber (UPNR). Examples of the modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Examples of the modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. Examples of the modified NR and modified IR also include NR and IR modified with a borane complex, as described below. One type of isoprene rubber may be used alone, or two or more types may be used in combination.

[0077] The content of the IR rubber in the rubber component is preferably more than 5% by mass, more preferably more than 10% by mass, even more preferably more than 15% by mass, and even more preferably 20% by mass or more. On the other hand, the content may be 50% by mass, but is preferably less than 45% by mass, more preferably less than 40% by mass.

[0078] (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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] Whether the raw material for a polymer is biomass-derived can be determined by the pMC (percent modern carbon) measured in accordance with ASTM D6866-10.

[0084] pMC is the modern standard reference 14 of sample against C concentration 14 This is the ratio of C concentrations and is a value used as an index of the biomass ratio of a compound. The significance of this value is explained below.

[0085] 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 elements.

[0086] 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.

[0087] this 14 C is typically measured using accelerator mass spectrometry based on a tandem accelerator. 13 C concentration ( 13 C / 12 C). 14 C concentration ( 14 C / 12 C) is measured. 14 The modern standard reference for the C concentration is the carbon circulating in nature as of 1950. 14The specific standard substance used is the oxalic acid standard provided by NIST (National Institute of Standards and Technology). The specific activity of carbon in this oxalic acid (per gram of carbon) is 14 The radioactivity of C is separated into carbon isotopes, 13 The standard value is the value corrected for decay from 1950 to the measurement date. 14 This is used as the C concentration value (100%). The ratio of this value to the value of the actually measured sample is the pMC value.

[0088] Therefore, if rubber is made from 100% biomass-derived materials, although there are regional differences, it will usually not reach 100 under normal conditions, so it will show a value of approximately 110 pMC. On the other hand, for chemical substances derived from petroleum and other fossil fuels, 14 When the carbon concentration is measured, it will show a value of about 0 pMC (for example, 0.3 pMC), which corresponds to the biomass ratio of 0% mentioned above.

[0089] From the above, it is preferable in terms of environmental protection to use materials such as rubbers with high pMC values, that is, materials such as rubbers with high biomass ratios, for crosslinked rubbers.

[0090] <Boron atom-containing group> The crosslinked rubber contains a boron atom-containing group. The boron atom-containing group is typically derived by compounding a compound containing the boron atom-containing group in its structural formula (hereinafter referred to as a boron atom-containing compound) into the crosslinked rubber separately from the rubber component. Alternatively, the boron atom-containing group can be incorporated into the crosslinked rubber using SBR, BR, or IR rubbers modified with a borane complex. The boron atom-containing compound can be any compound that contains boron in its molecule and has a functional group that can bond with the double bond of the polymer to crosslink the polymers, or that contains boron in its molecule and further contains a moiety that interacts with a filler.

[0091] Examples of boron atom-containing compounds in which a functional group in the molecule is bonded to a double bond of the polymer include compounds that form crosslinked moieties bonded via a boron-oxygen bond, compounds that form crosslinked moieties bonded via a boron-sulfur bond, compounds that form crosslinked moieties bonded via a boron-carbon bond, and compounds that form crosslinked moieties bonded via a boron-nitrogen bond. Of these, compounds that form crosslinked moieties bonded via a boron-oxygen bond are preferred.

[0092] Furthermore, examples of boron atom-containing compounds that contain a moiety in the molecule that interacts with the filler include the borane complexes described below.

[0093] (Compounds that form cross-linking sites linked via boron-oxygen bonds) The crosslinked rubber contains a compound that forms a crosslinking moiety bonded via a boron-oxygen bond. As a result, the crosslinked rubber has a crosslinking moiety bonded via a boron-oxygen bond. As the compound that forms a crosslinking moiety bonded via a boron-oxygen bond, a compound that forms a crosslinking moiety via a diboronic acid ester skeleton is preferred. Examples of such compounds 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 a crosslinking agent. When the diboronic acid ester compound is used to crosslink the polymers, the crosslinking site may contain a diboronic acid ester compound represented by 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:

[0094] X 1 Examples 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 a methylene group is preferred.

[0095] The compounds that form crosslinked moieties bonded via boron-oxygen bonds may be used alone or in combination of two or more.

[0096] The content of the compound that forms a crosslinking site bonded via a boron-oxygen bond, such as a diboronic acid ester compound, per 100 parts by mass of the rubber component may be more than 0 part by mass, for example, 1 part by mass or more, preferably 2 parts by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, while the content is 50 parts by mass or less, preferably 40 parts by mass or less, more preferably 35 parts by mass or less, and even more preferably 30 parts by mass or less.

[0097] (borane complex) Examples of borane complexes include complexes of nitrogen-containing aromatic compounds and borane compounds. Examples of nitrogen-containing aromatic compounds 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). Borane compounds may be any compounds having at least one B-H bond, and examples of such compounds include borane (BH), alkylborane, dialkylborane, arylborane, diarylborane, and alkylarylborane.

[0098] Examples of the complex of the nitrogen-containing aromatic compound and the borane compound include pyridine borane, picoline borane, pyrrole borane, and aniline borane.

[0099] In the complex of the nitrogen-containing aromatic compound and the borane compound, boron is bonded 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. This improves the dispersibility of the filler, which is thought to solve the problem of improving durability.

[0100] The amount of the borane complex is less than 20 parts by mass, preferably less than 18 parts by mass, more preferably less than 15 parts by mass, and even more preferably less than 13 parts by mass, per 100 parts by mass of the rubber component. On the other hand, the lower limit of the amount of the borane complex may be more than 0 parts by mass, and is, for example, 1 part by mass or more, preferably 2 parts by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more.

[0101] As described above, SBR can be modified with the borane complex, and the resulting modified SBR can be used as a rubber component. The content of the borane complex in the modified SBR can be the same as the content of the borane complex in the crosslinked rubber.

[0102] <Radical initiator> When a compound that forms a crosslinking moiety bonded via a boron-oxygen bond, such as the diboronic acid ester compound, is incorporated, it is preferable to incorporate 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.

[0103] The amount of the radical initiator to be mixed is not particularly limited, but can be set to 0.1 parts by mass or more and 3 parts by mass or less per 100 parts by mass of the rubber component.

[0104] <Filler> The crosslinked rubber may contain a filler. Examples of fillers include those commonly used in the tire industry, such as carbon black and silica. Examples of fillers other than carbon black and silica include aluminum hydroxide, calcium carbonate, alumina, clay, and talc. The filler may contain carbon black and silica, may consist of only carbon black and silica, or may consist of only silica or carbon black.

[0105] (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.

[0106] The average primary particle diameter of carbon black is preferably 5 nm or more, more preferably 8 nm or more, even more preferably 12 nm or more, and particularly preferably 15 nm or more. By setting the average primary particle diameter of carbon black within the above range, it is thought that the rubber molecules bound by the carbon black are minimized, allowing them to move flexibly, thereby enabling the polymer molecular chain to relieve stress in response to input. Meanwhile, the average primary particle diameter is preferably 90 nm or less, more preferably 75 nm or less, and even more preferably 60 nm or less. The average primary particle diameter of carbon black is measured by the above-mentioned measurement method.

[0107] 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 40m 2 / g is more preferable, and 50m 2 / g or more is more preferable, and 60m 2 / g or more is more preferable, and 70m 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 / g is more preferable, and 110m 2 / g is more preferable, and 100m 2 / g is more preferable, and 90m 2 / g or less is more preferable. In this specification, the N2SA of carbon black is a value measured in accordance with JIS K 6217-2:2017.

[0108] 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).

[0109] 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.

[0110] The carbon black content is, for example, more than 3 parts by mass, preferably more than 4 parts by mass, and more preferably 5 parts by mass or more, per 100 parts by mass of the rubber component. On the other hand, the total content is preferably less than 100 parts by mass, more preferably less than 80 parts by mass, and even more preferably less than 60 parts by mass. When the carbon black content is within the above range, good dispersion in the rubber is obtained, and sufficient reinforcement tends to be obtained.

[0111] (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.

[0112] 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.

[0113] 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.

[0114] When silica crystallizes, it becomes insoluble in water, and its component, silicic acid, cannot be utilized. By controlling the combustion temperature and duration, it is possible to suppress the crystallization of silica in rice husk ash (see, for example, JP 2009-2594 A and Akita Prefectural University Web Journal B / 2019, vol. 6, pp. 216-222).

[0115] Amorphous silica extracted from rice husks may be commercially available from Wilmar Co., Ltd., etc.

[0116] The nitrogen adsorption specific surface area (N2SA) of the silica is preferably 50 m 2 / g, more preferably 100m 2 / g, more preferably 150m 2 / 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.

[0117] 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.

[0118] When silica is contained, the content per 100 parts by mass of the rubber component is not particularly limited, but from the viewpoint of durability and, when a borane complex is compounded, from the viewpoint of obtaining a strong interaction with the nitrogen-containing aromatic compound, it is preferably more than 1 part by mass, more preferably more than 5 parts by mass, more preferably more than 10 parts by mass, and even more preferably more than 20 parts by mass. Also, from the viewpoints of dispersibility and processability of the silica, the content is preferably less than 150 parts by mass, more preferably less than 100 parts by mass, even more preferably less than 50 parts by mass, and even more preferably less than 30 parts by mass.

[0119] (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.

[0120] 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.

[0121] <Other compounding agents> In addition to the rubber component and filler, the crosslinked rubber 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.

[0122] (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.

[0123] <Resin> The crosslinked rubber may contain a resin among the other compounding ingredients. 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, C9 resins, and terpene resins are preferred. These resins may be used alone or in combination of two or more.

[0124] 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, and may be a hydrogenated or modified version of such a compound. 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, for example, commercially available products from Kraton, Eastman Chemical Company, Mitsui Chemicals, Inc., etc. can be used. One type of such resin may be used alone, or two or more types may be used in combination.

[0125] 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.

[0126] ·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.

[0127] ·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.

[0128] 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.

[0129] 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 largest content of the monomer component, 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.

[0130] 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 highest content, and may be a hydrogenated or modified version of such a rosin-based resin. 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.

[0131] 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.

[0132] 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.

[0133] <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.

[0134] 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 measure. Examples of low PCA oils include MES, TDAE, and heavy naphthenic oil. Mineral oils may be used singly or in combination.

[0135] 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.

[0136] 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.

[0137] 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.

[0138] 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.

[0139] 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.

[0140] 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.

[0141] Examples of animal oils include fish oil, beef tallow, and oleyl alcohol derived from these.

[0142] The oil content per 100 parts by mass of the rubber component is preferably more than 1 part by mass, more preferably more than 2 parts by mass, and even more preferably 3 parts by mass or more. The content is preferably less than 20 parts by mass, more preferably less than 15 parts by mass, 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.

[0143] <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.

[0144] <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.

[0145] When a plasticizer is contained, the content per 100 parts by mass of the rubber component is preferably more than 1 part by mass, more preferably more than 1.5 parts by mass, even more preferably 2 parts by mass or more, and still more preferably 3 parts by mass or more, while the content is preferably less than 40 parts by mass, more preferably less than 20 parts by mass, and even more preferably less than 10 parts by mass.

[0146] (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.

[0147] 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.

[0148] (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.

[0149] 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.

[0150] (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.

[0151] (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.

[0152] 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.

[0153] (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.

[0154] (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.

[0155] (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.

[0156] 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.

[0157] (Crosslinking agent) The crosslinking between polymers in the crosslinked rubber is not limited to crosslinking via boron-oxygen bonds, and may 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.

[0158] 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.

[0159] 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.

[0160] 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. In this case, the content of the crosslinking agent refers to the content of the crosslinking agent related to crosslinks other than those formed via boron-oxygen bonds. 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.

[0161] <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 may be used in combination.

[0162] 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.

[0163] The content of the vulcanization accelerator per 100 parts by mass of the rubber component is preferably more than 0.3 parts by mass, more preferably more than 0.5 parts by mass, and even more preferably 1.0 part by mass or more. On the other hand, the content 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. When the content of the vulcanization accelerator is within the above range, breaking strength and elongation tend to be ensured.

[0164] 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.

[0165] [Cross-linked rubber that makes up the inner liner] The crosslinked rubber constituting the inner liner will be described. The crosslinked rubber constituting the inner liner will be described below, and the description of the crosslinked rubber constituting the cap tread can be applied in the same manner as long as it does not contradict these descriptions.

[0166] (rubber component) The rubber component preferably contains a butyl-based rubber. In this case, the rubber component may contain a rubber component other than the butyl-based rubber. Examples of rubber components other than the butyl-based rubber include diene-based rubbers such as isoprene-based rubber (IR rubber), styrene-butadiene rubber (SBR), and butadiene rubber (BR), as well as the non-diene-based rubbers described above. Rubber components synthesized from recycled or biomass-derived raw materials can also be used. The butyl-based rubber, diene-based rubber, and non-diene-based rubber may each be used alone or in combination of two or more.

[0167] <Butyl rubber> 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.

[0168] 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.

[0169] The explanations given for the crosslinked rubber constituting the cap tread are similarly applicable to the explanations for the boron atom-containing compound, filler, and other compounding ingredients.

[0170] [Crosslinked rubber that constitutes rubber components other than cap tread and inner liner] For example, the crosslinked rubber constituting the base tread, sidewall, clinch apex, wing, and other rubber members other than the cap tread and inner liner can be similarly applied to the crosslinked rubber constituting the cap tread.

[0171] <Production method> The tire according to this embodiment can be manufactured by a known method.

[0172] (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.

[0173] (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 rubber 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.

[0174] <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]

[0175] 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 these working examples. Tires obtained according to each table were examined using the various chemicals shown below, and the results calculated based on the evaluation method below are shown as durability indices at the bottom of each table.

[0176] <Various chemicals> The various chemicals used in the examples and comparative examples are summarized below. IR rubber: Natural rubber (TSR-20) SBR1: SBR produced in Production Example 1 described below (styrene content: 30% by mass, vinyl content: 10% by mole, Mw: 400,000) SBR2: SBR produced in Production Example 2 described below (styrene content: 30% by mass, vinyl content: 50% by mole, Mw: 450,000) SBR3: Hydrogenated SBR produced in Production Example 3 described below (styrene content: 30% by mass, vinyl content (before hydrogenation): 25% by mol, ethylene units: 90% by mol, butadiene units: 10% by mol, hydrogenation rate: 95%, Mw: 400,000) BR: butadiene rubber (UBE Elastomers Co., Ltd., BR150B, cis content: 97 mol%, vinyl content: 1 mol%) Pyridine borane (Tokyo Chemical Industry Co., Ltd., molecular weight 92.94, boron atomic weight 10.81, purity 80%) BDB: Diboronic acid ester compound represented by the following formula (synthetic product in-house, molecular weight 310.01, total boron atom weight 21.62) [ka] CB: Diablack N220 (Mitsubishi Chemical Corporation, N2SA: 115 m 2 / g) Silica: Ultrasil VN3 (manufactured by Evonik Degussa, N2SA: 175 ml 2 / g, average primary particle diameter: 17nm) Silane coupling agent: Si266 (Evonik Degussa, bis(3-triethoxysilylpropyl) disulfide) Wax: Ozoace 0355 (Nippon Seiro Co., Ltd., paraffin-based) Antioxidant 1: Nocrac 6C (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) Antioxidant 2: Nocrac RD (Ouchi Shinko Chemical Industry Co., Ltd., poly(2,2,4-trimethyl-1,2-dihydroquinoline)) Zinc oxide: Zinc oxide No. 1 (manufactured by Mitsui Mining & Smelting Co., Ltd.) Stearic acid: Camellia stearate beads (NOF Corporation) Radical initiator: azobisisobutyronitrile (AIBN, manufactured by Tokyo Chemical Industry Co., Ltd.) Sulfur: HK-200-5 (Hosoi Chemical Industry Co., Ltd., powdered sulfur, oil content: 5% by mass) Vulcanization accelerator 1: Noccelaer D (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., N,N'-diphenylguanidine (DPG)) Vulcanization accelerator 2: Noccela DM-P (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., di-2-benzothiazolyl disulfide (MBTS)) Vulcanization accelerator 3: Noccela NS (Ouchi Shinko Chemical Industry Co., Ltd., N-(tert-butyl)-2-benzothiazole sulfenamide (TBBS))

[0177] Manufacturing Example 1: Manufacturing of SBR1 A nitrogen-purged autoclave reactor was charged with 600 mL of hexane, 75 g of 1,3-butadiene, 25 g of styrene, and 60 mL of tetrahydrofuran and stirred at 40°C. After adding 0.5 mL of 0.1 mol / L n-butyllithium / hexane solution in 0.5 mL increments for scavenging, 4 mL of 0.1 mol / L n-butyllithium / hexane solution was added, and the stirring speed was increased to 130 rpm and the jacket temperature to 80°C. After confirming the formation of a polymer with a Mw of 250,000 by GPC, the polymerization solution was poured into 4 L of ethanol and the precipitate was collected. The resulting precipitate was blown dry and then vacuum dried at 80°C / 10 Pa or less until the loss on drying was 0.1%, yielding SBR1.

[0178] Production Example 2: Synthesis of SBR2 SBR2 is obtained in the same manner as in Production Example 1, except that the ratio of styrene to 1,3-butadiene is adjusted so that the vinyl content is 50 mol %.

[0179] Production Example 3: Synthesis of hydrogenated SBR A heat-resistant reactor containing 2000 mL of n-hexane, 60 g of styrene, 140 g of 1,3-butadiene, 0.9 g of TMEDA (N,N,N',N'-tetramethylethylenediamine), and 0.45 mmol of n-butyllithium were placed in a thoroughly nitrogen-purged vessel and stirred at 50°C for 5 hours to carry out the polymerization reaction. Hydrogen gas was then introduced at 0.4 MPa-gauge pressure while stirring for 20 minutes to react with unreacted lithium at the polymer terminals, producing lithium hydride. Hydrogenation was carried out using a titanocene dichloride-based catalyst at a hydrogen gas supply pressure of 0.7 MPa-gauge and a reaction temperature of 90°C. When the cumulative amount of hydrogen absorption reached the target hydrogenation rate, the reaction temperature was lowered to room temperature, the hydrogen pressure was returned to normal, and the reactor was withdrawn. The reaction solution was then stirred into water and the solvent removed by steam stripping to obtain hydrogenated SBR. The resulting hydrogenated SBR was evaluated as follows.

[0180] Measurement of hydrogenation rate A 15% by mass solution was prepared using carbon tetrachloride as a solvent, and a 100 MHz 1It is calculated from the spectral reduction rate of the unsaturated bond in H-NMR.

[0181] Styrene content measurement At 25°C, using a JEOL JNM-A 400 NMR instrument 1 H-NMR is measured, and the styrene content is determined from the ratio of phenyl protons based on styrene units at 6.5 to 7.2 ppm to vinyl protons based on butadiene units at 4.9 to 5.4 ppm, which is obtained from the spectrum.

[0182] Measurement of weight average molecular weight (Mw) Mw is determined by converting it into standard polystyrene based on the measured value obtained by gel permeation chromatography (GPC) (GPC-8000 series manufactured by Tosoh Corporation, detector: differential refractometer, column: TSKGEL SUPERMULTIPORE HZ-M manufactured by Tosoh Corporation).

[0183] The resulting hydrogenated SBR has a hydrogenation rate of 95 mol %, a styrene content of 30 mass %, and a weight average molecular weight (Mw) of 400,000.

[0184] <Rubber composition for cap tread and tire> According to the compounding recipes shown in Tables 1 and 3, the chemicals other than sulfur and the vulcanization accelerator are kneaded for 4 minutes using a 1.7 L internal Banbury mixer until the discharge temperature reaches 130°C, to obtain a kneaded mixture. Next, using a two-screw open roll, sulfur and the vulcanization accelerator are added to the kneaded mixture, and the mixture is kneaded for 4 minutes until the temperature reaches 80°C, to obtain an uncrosslinked rubber composition for cap tread.

[0185] According to the descriptions in Tables 1 and 3, the uncrosslinked rubber composition for cap tread is molded into the shape of a cap tread, and then laminated with other components to form an uncrosslinked tire, which is then press-vulcanized (crosslinked) for 12 minutes under the condition of 170°C to produce each test tire (size: 195 / 65R15). Note that the thickness of the base tread is constant regardless of the thickness of the cap tread.

[0186] <Sidewall rubber composition and tire> According to the compounding recipe shown in Table 2, chemicals other than sulfur and vulcanization accelerator are kneaded for 5 minutes at a discharge temperature of 150°C using a 1.7 L internal Banbury mixer. Next, sulfur and vulcanization accelerator are added to the kneaded mixture obtained, and the mixture is kneaded with an open roll for 4 minutes until the temperature reaches 105°C, to obtain an uncrosslinked rubber composition for the sidewall.

[0187] According to the description in Table 2, the uncrosslinked rubber composition for the sidewall is molded into the shape of the sidewall, and then laminated with other components to form an uncrosslinked tire. A test tire (size: 195 / 65R15) is manufactured by press-vulcanizing (crosslinking) the tire at 170°C for 12 minutes.

[0188] <Durability> Each test tire is mounted on a standard rim and inflated to an internal pressure of 230 kPa. The tire is then mounted on a drum-type running test machine and subjected to a standard load. The tire is run on the drum at a speed of 80 km / h, and the running distance is measured until peeling or damage occurs to the components. The results are expressed as an index, with the running distance of the comparison standard example being 100. The higher the number, the better the performance.

[0189] [Table 1]

[0190] [Table 2]

[0191] [Table 3]

[0192] The reference comparative examples in Tables 1 to 3 above are as follows: Table 1: Comparative Examples 1-2 Table 2: Comparative Example 2-1 Table 3: Comparative Example 3-1

[0193] <Embodiment> The following describes a preferred embodiment.

[0194] [1] A tire having at least one rubber member made of a crosslinked rubber containing a rubber component and a crosslinking agent, wherein the crosslinked rubber contains a boron atom-containing group, and the rubber component contains a polymer containing, as repeating units, -CH=CH- units, -CH2-CH(-CH=CH2)- units, and -CH2-CHPh- units (wherein Ph represents a phenyl group), and the content of the polymer in the rubber component is 50% by mass or more, and the tire simultaneously satisfies the following relational formulas (1) and (2), where B is the boron content (parts by mass) in the crosslinked rubber relative to 100 parts by mass of the rubber component, Y is the content (parts by mass) of -CH2-CH(-CH=CH2)- units in the rubber component relative to 100 parts by mass of the rubber component, and T is the thickness (mm) of the rubber member. (1) Y<6.0 (2) B / (Y×T)×10 4 >1 [2] The tire according to [1], wherein the thickness T of the rubber member made of the crosslinked rubber is 5 mm or less. [3] The tire according to [1] or [2], wherein the rubber component further contains an isoprene-based rubber. [4] The tire according to any one of [1] to [3], wherein the right side of formula (1) is 5.0, preferably 4.5. [5] The tire according to any one of [1] to [3], wherein the right side of formula (1) is 4.2, preferably 4.0, more preferably 3.5, even more preferably 3.0, even more preferably 2.5, even more preferably 2.0, and even more preferably 1.5. [6] The tire according to any one of [1] to [4], wherein the right side of formula (2) is 100, preferably 400, more preferably 800, even more preferably 1000, even more preferably 2000, and even more preferably 4000. [7] The tire according to any one of [1] to [5], wherein the left side of formula (2) is less than 5,000. [8] The tire according to any one of [1] to [6], wherein the polymer further contains -CH2-CH2-CH2-CH2- units and / or -CH2-CH(-CH2-CH3)- units. [9] The tire according to any one of [1] to [7], wherein the crosslinked rubber has crosslinking sites bonded via boron-oxygen bonds.

[10] The tire according to [9], wherein the crosslinking site includes a group having a diboronic acid ester skeleton unit.

[11] The tire according to any one of [1] to

[10] , wherein the polymer is a modified polymer modified with a complex of a nitrogen-containing aromatic compound and a borane compound.

[12] The tire according to

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

[13] The tire according to any one of [1] to

[12] , 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. [Explanation of symbols]

[0195] 1 Cap Tread 2 Base Tread 3 Inner liner 4 Sidewall 5 Clinch Apex 6 Wing CL Tire centerline R rim T1 Cap tread thickness T2 Base tread thickness T3 Inner liner thickness T4 Sidewall Thickness T5 Clinch Apex Thickness T6 Wing Thickness

Claims

1. A tire having at least one rubber member made of a crosslinked rubber containing a rubber component and a crosslinking agent, the crosslinked rubber contains a boron atom-containing group, The rubber component has a repeating unit of -CH=CH- unit, -CH 2 -CH(-CH=CH 2 )-units, and -CH 2 a polymer containing -CHPh- units (wherein Ph represents a phenyl group); The content of the polymer in the rubber component is 50% by mass or more, The boron content (parts by mass) in the crosslinked rubber relative to 100 parts by mass of the rubber component is B, and the —CH 2 -CH(-CH=CH 2 )-unit content (parts by mass) is Y, and the thickness (mm) of the rubber member is T. A tire that simultaneously satisfies the following relational expressions (1) and (2): (1) Y<6.0 (2) B / (Y×T)×10 4 >1

2. The tire according to claim 1, wherein the thickness T of the rubber member made of the crosslinked rubber is 5 mm or less.

3. The tire according to claim 1 or 2, wherein the rubber component further contains an isoprene-based rubber.

4. The tire according to claim 1 or 2, wherein the right-hand side of formula (1) is 5.

0.

5. The tire according to claim 1 or 2, wherein the right-hand side of formula (1) is 4.

2.

6. The tire according to claim 1 or 2, wherein the right side of formula (2) is 100.

7. The tire according to claim 1 or 2, wherein the left side of formula (2) is less than 5,000.

8. The polymer is -CH 2 -CH 2 -CH 2 -CH 2 - units and / or -CH 2 -CH(-CH 2 -CH 3 3. The tire of claim 1 or 2, further comprising .alpha.-units.

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

10. The tire of claim 9 , wherein the crosslinking site comprises a group having a diboronic ester backbone unit.

11. 3. The tire according to claim 1, wherein the polymer is a modified polymer modified with a complex of a nitrogen-containing aromatic compound and a borane compound.

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

13. 3. 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.

Images