Tire

Abstract

To provide a tire which is excellent in on-ice gripping performance.SOLUTION: A tire includes a tread part having at least one block land part, wherein the block land part has a sipe, density Ds (1 / mm) in a tire circumferential direction of a width direction component of the sipe is 0.15 or more, a rubber layer constituting a tread ground contact surface of the tread part is composed of a rubber composition containing a copolymer resin containing a rubber component containing styrene butadiene rubber, silica, and a monomer component containing styrene and dicyclopentadiene, and when the mass of the rubber component is 100 mass%, when a total styrene amount (mass%) in the rubber composition is represented by St, St and Ds satisfy the following expression (1): St×Ds>0.50.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] On frozen roads, the heat generated by friction between the tread surface and the ice melts the ice, creating a water film between the tread surface and the road surface, making the tire more susceptible to slipping. Patent Document 1 describes how providing fine protrusions on the tread surface can improve grip performance on ice. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-181258 Summary of the Invention [Problem to be solved by the invention]

[0004] However, further improvements are needed in terms of grip on ice.

[0005] An object of the present invention is to provide a tire that has excellent grip performance on ice. [Means for solving the problem]

[0006] The present invention relates to the following tire. A tire having a tread portion having at least one block land portion, The block land portion has a sipe, The density Ds (1 / mm) of the width direction component of the sipe in the tire circumferential direction is 0.15 or more, the rubber layer constituting the tread ground contact surface of the tread portion is made of a rubber composition containing a rubber component including styrene-butadiene rubber, silica, and a copolymer resin including styrene and dicyclopentadiene as monomer components; A tire in which, when the mass of the rubber component is 100 mass %, the total amount of styrene (mass %) in the rubber composition is St, St and Ds satisfy the following formula (1): (1) St × Ds > 0.50 [Effects of the Invention]

[0007] According to the present invention, a tire having excellent grip performance on ice can be provided.

[0008] While not intending to be bound by theory, the following mechanism is believed to be responsible for the improved ice grip performance in the present invention. Specifically, (1) Silica-reinforced styrene-butadiene rubber and a copolymer resin containing styrene and dicyclopentadiene (DCPD) as monomer components have similar SP values ​​and are therefore easily compatible. This reduces the distance between bulky functional groups, increasing intermolecular friction and resulting in increased energy loss, which is believed to contribute to improved ice grip performance. (2) Increasing sipe density increases the range of motion near the rubber surface, increasing deformation during friction with the icy road surface, which in turn increases energy loss and contributes to improved ice grip performance. Furthermore, the cooperation of (1) and (2) above is believed to synergistically improve ice grip performance. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a development view that schematically shows a tread pattern of a tire according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram of a block land portion for illustrating an example of calculating a sipe density Ds. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a tire according to one embodiment of the present invention will be described. The tire according to this embodiment has a tread portion having at least one block land portion, the block land portion having a sipe, the width direction component of the sipe having a tire circumferential density Ds (1 / mm) of 0.15 or more, the rubber layer constituting the tread contact surface of the tread portion being made of a rubber composition containing a rubber component including styrene-butadiene rubber and a copolymer resin containing silica and styrene and dicyclopentadiene as monomer components, and when the mass of the rubber component is 100 mass%, the total styrene content (mass %) in the rubber composition is St, and the tire is characterized in that St and Ds satisfy the following formula (1): (1) St × Ds > 0.50

[0011] The content (mass%) of the styrene butadiene rubber in the rubber component is A SBR If A SBR and St preferably satisfy the following formula (2): By satisfying formula (2), the glass transition temperature of the rubber is lowered and the flexibility of the rubber is improved, which is thought to enable the rubber to conform to the icy road surface and improve grip performance on ice. (2) St / A SBR ×100<25.0

[0012] The right side of formula (1) is preferably 0.82, and more preferably 1.00. It is believed that the effects of the present invention are more easily achieved by satisfying formula (1) under stricter conditions.

[0013] The right-hand side of formula (2) is preferably 20.0, and more preferably 15.0. By satisfying formula (2) under stricter conditions, the glass transition temperature of the rubber is further lowered, improving the flexibility of the rubber, which is thought to enable it to conform to the icy road surface and improve grip performance on ice.

[0014] The rubber component preferably contains at least one rubber selected from the group consisting of isoprene-based rubber and butadiene rubber, and the performance of blending these other rubber components with styrene-butadiene rubber can be exhibited.

[0015] The rubber composition contains carbon black, and the content (parts by mass) of the silica relative to 100 parts by mass of the rubber component is A SIL The content (parts by mass) of the carbon black relative to 100 parts by mass of the rubber component is A CB If A SIL / A CB It is preferable that the ratio is greater than 1.0. The rubber component reinforced with silica is thought to contribute to improved grip performance.

[0016] When the tire weight is G (kg), St / G is preferably 3.0 or less. Since the force pressing the land portion against the road surface decreases as the tire becomes lighter, it is thought that by reducing the total styrene content as the tire becomes lighter, it is possible to suppress the adverse effects on the tread surface caused by aggregation of the styrene portion.

[0017] The tread contact surface has three or more circumferential main grooves, and when a pair of the circumferential main grooves located on the outermost sides in the tire width direction are the outermost circumferential main grooves, it is preferable that the groove width of at least one of the outermost circumferential main grooves is narrower than the groove width of at least one circumferential main groove that is not the outermost circumferential main groove. Narrowing the groove width of the outermost circumferential main groove can increase the reaction force in the shoulder region when the tire corners, which is thought to contribute to improving grip performance.

[0018] The rubber composition preferably contains 30 to 70 parts by mass of a softener per 100 parts by mass of the rubber component. It is believed that 30 parts by mass or more of the softener improves workability when handling the rubber composition, and 70 parts by mass or less can maintain good tire appearance.

[0019] 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.

[0020] [Definition] The "tread portion" refers to a component that includes the portion that forms the tread contact surface of the tire, and in the case where components that reinforce and form the tire frame, such as a reinforcing layer or carcass, are provided on the tire radially inner side in the tire cross section, the "tread portion" refers to a component that is located on the tire radially outer side of these components.

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

[0022] The term "block land portion" refers to a land portion that is defined by circumferential main grooves formed on the tread contact surface and further divided into blocks by widthwise grooves. Figure 1 shows a block land portion 41 as an example of the block land portion.

[0023] "Sipe" means a small notch having a width of 2.0 mm or less.

[0024] "Sipe density Ds" is an index that indicates the density at which the tire width direction component of the sipes provided in the block land portion is arranged in the tire circumferential direction. Ds (1 / mm) is the area (mm 2 ) is the maximum width B of the block land portion in the tire width direction W The equivalent circumferential length of the block land area divided by B L(mm), and the total (mm) of the tire width direction components of all sipes provided on the block land portion is B W When the number of equivalent sipes in the block land area divided by N is the average sipe spacing in the tire circumferential direction, B L That is, the sipe density Ds is expressed by the following formula: Ds=(N+1) / B L

[0025] The "total styrene content St in the rubber composition" refers to the total styrene content (% by mass) in the rubber composition when the mass of the rubber component is 100% by mass, and is the sum of the content of styrene moieties contained in the rubber component and the content of styrene moieties contained in the compounding ingredients other than the rubber component. That is, first, for each rubber component, the styrene content (% by mass) is multiplied by the mass fraction in the rubber component to calculate a value, and these values ​​are added together to obtain a total value (% by mass). Next, for the styrene-containing compounding ingredients other than the rubber component contained in the rubber composition, the styrene content (% by mass) of each styrene-containing compounding ingredient is multiplied by the mass fraction relative to 100 parts by mass of the rubber component to calculate a value, and these values ​​are added together to obtain a total value (% by mass). The sum of these two sums is the total styrene content St (% by mass). Therefore, it is calculated by {Σ(styrene content (% by mass) of each styrene-containing rubber × content of each styrene-containing rubber in the rubber component (% by mass) / 100) + Σ(styrene content (% by mass) of each styrene-containing compounding ingredient other than the rubber component × compounding amount (parts by mass) of each styrene-containing compounding ingredient per 100 parts by mass of the rubber component) / 100)}. For example, if the rubber component consists of 30% by mass of a first SBR (styrene content: 25% by mass), 60% by mass of a second SBR (styrene content: 27.5% by mass), and 10% by mass of BR, and the rubber composition further contains, in addition to the rubber component, 20 parts by mass of a first resin having a styrene moiety (styrene content: 5% by mass) and 10 parts by mass of a second resin having a styrene moiety (styrene content: 1% by mass) per 100 parts by mass of the rubber component, the total styrene amount St in the rubber composition per 100% by mass of the rubber component is 25.1% by mass = {(25 × 30 / 100 + 27.5 × 60 / 100 + 0 × 10 / 100) + (5 × 20 / 100 + 1 × 10 / 100)}.

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

[0027] 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.

[0028] "Genuine rim" refers to the rim specified for each tire by the standard system, including 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 tires 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).

[0029] "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.

[0030] "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.

[0031] "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.

[0032]

number

[0033] "Weight of tire" refers to the weight of the tire itself, excluding the weight of the rim. On the other hand, if the tire has components such as sponge or sealant, or sensor components, the weight includes these components.

[0034] The "tread contact edge" refers to the outermost contact position in the tire width direction when a normal load is applied to a tire in a normal state and the tire contacts a flat surface with a camber angle of 0 degrees (Te1, Te2).

[0035] A "circumferential main groove" refers to a groove that extends continuously in the circumferential direction of the tire and has a width of 3.0 mm or more at the tread contact surface. The circumferential main groove may extend linearly along the circumferential direction, or may extend in a wavy, sinusoidal, or zigzag pattern along the circumferential direction.

[0036] "Land portion" refers to the area on the tread surface defined by the circumferential main grooves.

[0037] "Width groove" refers to a groove that extends in the width direction of the tire and has a width at the tread contact surface of more than 2.0 mm. "Extending in the width direction of the tire" means that the angle between the line connecting both ends of the groove and the tire centerline is 45° or less.

[0038] "Groove width" means the distance between the groove walls. The groove width can be recognized at each position along the extension direction of the groove from the tread surface to the groove bottom.

[0039] A "softener" is a material that imparts plasticity to the rubber component, and is a concept that includes both softeners that are liquid at room temperature (25°C) and softeners that are solid at room temperature (25°C). Examples of softeners include resins, oils, liquid rubbers, and ester-based plasticizers. The "softener content" also includes the amount of softener in the rubber component that has been extended by the softener.

[0040] [Measurement method] "Styrene content" is 1 This is a value calculated by H-NMR measurement, and is applied to rubber components having repeating units derived from styrene, such as SBR.

[0041] The "vinyl content (amount of 1,2-bonded butadiene units)" is a value calculated by infrared absorption spectroscopy in accordance with JIS K 6239-2:2017, and applies to rubber components having repeating units derived from butadiene, such as SBR and BR.

[0042] The "cis content (cis-1,4-bond content)" is a value calculated by infrared absorption spectroscopy in accordance with JIS K 6239-2:2017, and applies to rubber components having repeating units derived from butadiene, such as BR.

[0043] 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.

[0044] 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, etc.

[0045] "N2SA of carbon black" is measured in accordance with JIS K 6217-2:2017.

[0046] "N2SA of silica" is measured by the BET method in accordance with ASTM D3037-93.

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

[0048] The "softening point of the resin" is the temperature at which the ball drops when the softening point specified in JIS K 6220-1:2015 7.7 is measured using a ring and ball softening point tester.

[0049] [tire] A tire according to one embodiment of the present invention will be described below with reference to the accompanying drawings. However, the drawings used merely illustrate one embodiment, and the present invention is not limited to these drawings.

[0050] The tire according to this embodiment is a tire having a tread portion having a rubber layer that forms a tread contact surface made of a predetermined rubber composition, the tread portion having at least one block land portion, the block land portion having a sipe, the density Ds (1 / mm) of the width direction component of the sipe in the tire circumferential direction is 0.15 or more, and when the mass of the rubber component is 100 mass%, and the total styrene amount (mass%) in the rubber composition is St, St and Ds satisfy the following formula (1): (1) St × Ds > 0.50

[0051] FIG. 1 is a development view that schematically illustrates the tread pattern of a tire according to this embodiment. The tread pattern includes a linear circumferential main groove 21 that runs along the tire centerline and a pair of linear outermost main grooves 22 arranged on either side of the circumferential main groove 21. It also includes a widthwise groove 31 that connects the outermost main groove 22 to the tread ground-contact edge Te in the tire width direction, and a widthwise groove 32 that connects the outermost main groove 22 to the circumferential main groove 21 in the tire width direction. CL represents the tire centerline, W represents the tire width direction, and C represents the tire circumferential direction. In FIG. 1, the region defined by the circumferential main groove and the widthwise groove is a block land portion 41. Sipes 11 are formed in the block land portion 41.

[0052] In Fig. 1, the number of circumferential main grooves is three, but in this embodiment, the number of circumferential main grooves is not particularly limited and may be more or less than three. In Fig. 1, the circumferential main grooves are linear, but in this embodiment, the circumferential main grooves are not limited to linear grooves and may extend in a wavy, sinusoidal, or zigzag pattern along the circumferential direction. In Fig. 1, all widthwise grooves connect adjacent circumferential main grooves or connect the outermost circumferential main groove and the tread ground-contact edge, but grooves that do not provide such connections may extend in the width direction.

[0053] The sipe density Ds in a block land portion is an index that indicates how densely the tire width direction component of the sipes 11 is arranged in the tire circumferential direction in the block land portion 41 in FIG. 1. FIG. 2 is a schematic diagram of a block land portion to show an example of calculating the sipe density Ds. For convenience, in FIG. 2, the block land portion 41 is shown as a rectangle defined by a line parallel to the tire circumferential direction and a line parallel to the tire width direction. The tire circumferential length B of the block land portion 41 is L is 36mm, the maximum width B in the tire width direction W is set to 25 mm. Five sipes 11 are arranged, and the equivalent number of sipes N is 5. Therefore, the sipe density Ds (1 / mm) of the block land portion 41 in FIG. 2 is (5+1) / 36=0.17.

[0054] <Formula (1)> The value of the right side of formula (1) is preferably 0.80, more preferably 0.82, even more preferably 1.00, even more preferably 1.10, even more preferably 1.45, even more preferably 1.70, and even more preferably 1.78. There is no particular upper limit to the value of St×Ds on the left side of formula (1), but it can usually be assumed to be about 5.00 or about 10.00.

[0055] Regarding formula (1), the total styrene content St can be adjusted by increasing or decreasing the content of the rubber component containing a styrene moiety, or by increasing or decreasing the content of compounding ingredients other than the rubber component containing a styrene moiety. Furthermore, the sipe density Ds can be adjusted by increasing or decreasing the tire width direction component of the sipes arranged in the block land portion. Therefore, the value of St × Ds in formula (1) can be adjusted to be larger or smaller.

[0056] <Formula (2)> The content (mass%) of the styrene butadiene rubber in the rubber component is A SBR If A SBR and St preferably satisfy the following formula (2). (2) St / A SBR ×100<25.0

[0057] The value of the right side of formula (2) is preferably 20.0, more preferably 15.0, even more preferably 14.0, and still more preferably 13.5. SBR There is no particular limit to the lower limit of the value, but it can usually be assumed to be around 5.0 or 10.0.

[0058] Regarding formula (2), the total styrene content St can be adjusted as described above. The content of SBR in the rubber component can be adjusted by increasing or decreasing the amount of SBR blended. Therefore, St / A in formula (2) SBR The x100 value can be adjusted to be larger or smaller.

[0059] <st g> When the tire weight is G (kg), St / G is preferably 3.0 or less. Here, St / G is more preferably 2.5 or less, even more preferably 2.0 or less, even more preferably 1.5 or less, even more preferably 1.2 or less, and even more preferably 1.0 or less. On the other hand, the lower limit of St / G is not particularly limited, but is usually about 0.5 or more.

[0060] <Outermost circumferential main groove width> When the tread contact patch has three or more circumferential main grooves, and a pair of the circumferential main grooves located outermost in the tire width direction are outermost main grooves, it is preferable that the groove width of at least one of the outermost main grooves is narrower than the groove width of at least one circumferential main groove that is not the outermost main groove. Here, it is preferable that the groove widths of all of the outermost main grooves are narrower than the groove width of at least one circumferential main groove that is not the outermost main groove, and it is further preferable that the groove widths of all of the outermost main grooves are narrower than the groove widths of all of the circumferential main grooves that are not the outermost main grooves.

[0061] [Rubber composition] The rubber composition constituting the rubber layer that constitutes the tread contact surface of the tire according to this embodiment will be described below.

[0062] The rubber composition includes a rubber component containing styrene-butadiene rubber (SBR), silica, and a copolymer resin containing styrene and dicyclopentadiene as monomer components.

[0063] <Rubber component> The rubber composition according to the present embodiment may contain a rubber component other than styrene-butadiene rubber, and examples of such a rubber component include diene rubber, non-diene rubber, etc. Of these, diene rubber is preferred, but non-diene rubber may also be contained within a range that does not affect the effects of the present invention.

[0064] The content of the diene rubber in the rubber component is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 99% by mass or more. The rubber component may consist solely of the diene rubber.

[0065] As the diene rubber, any of those commonly used in the tire industry can be suitably used, such as isoprene rubber, butadiene rubber (BR), styrene-isoprene rubber (SIR), styrene-isoprene-butadiene rubber (SIBR), chloroprene rubber (CR), and acrylonitrile-butadiene rubber (NBR). These diene rubbers may be used alone or in combination of two or more. As the non-diene rubber, rubber components commonly used in the tire industry can be used, such as butyl rubber, ethylene-propylene rubber, polynorbornene rubber, silicone rubber, chlorinated polyethylene rubber, fluororubber (FKM), acrylic rubber (ACM), and hydrin rubber. These other rubber components may be used alone or in combination of two or more. In addition to the above rubber components, a known thermoplastic elastomer may or may not be contained.

[0066] The rubber component according to the present embodiment preferably contains at least one rubber selected from the group consisting of styrene-butadiene rubber, isoprene-based rubber, and butadiene rubber. Another preferred embodiment of the rubber component according to the present embodiment contains styrene-butadiene rubber, isoprene-based rubber, and butadiene rubber. Another preferred embodiment of the rubber component according to the present embodiment consists of styrene-butadiene rubber, isoprene-based rubber, and butadiene rubber.

[0067] (SBR) The SBR is not particularly limited, and examples thereof include solution-polymerized SBR (S-SBR), emulsion-polymerized SBR (E-SBR), and modified SBRs thereof (modified S-SBR, modified E-SBR). Modified SBRs include SBRs whose ends and / or main chains are modified, and modified SBRs coupled with tin, silicon compounds, etc. (condensates, those having a branched structure, etc.). These SBRs may be used alone or in combination of two or more.

[0068] From the viewpoint of the effects of the present invention, the styrene content of SBR is preferably more than 7% by mass, more preferably more than 9% by mass, and even more preferably more than 11% by mass. On the other hand, from the viewpoints of uniformity of crosslinking and suppression of temperature dependency, the styrene content of SBR is preferably less than 60% by mass, more preferably less than 50% by mass, and even more preferably less than 45% by mass. In this specification, the styrene content of SBR is measured by the above-mentioned measurement method.

[0069] The vinyl content of SBR is preferably more than 10 mol%, more preferably more than 15 mol%, and even more preferably 18 mol% or more. The vinyl content of SBR is preferably less than 60 mol%, more preferably less than 40 mol%, and even more preferably less than 30 mol%. In this specification, the vinyl content of SBR is measured by the above-mentioned measurement method.

[0070] From the viewpoint of wet grip performance, the glass transition point (Tg) of SBR is preferably above −80° C., more preferably above −75° C., and even more preferably above −72° C. From the viewpoint of fuel economy performance, the Tg of SBR is preferably −30° C. or lower, more preferably −35° C. or lower, and even more preferably −40° C. or lower. In this specification, the Tg of SBR is measured by the above-mentioned measurement method.

[0071] The weight average molecular weight (Mw) of SBR is preferably more than 200,000, more preferably more than 300,000, and even more preferably more than 400,000. From the viewpoint of crosslinking uniformity, Mw is preferably less than 2,000,000, more preferably less than 1,500,000, and even more preferably less than 1,000,000. The Mw of SBR is measured by the above-mentioned measurement method.

[0072] As the SBR, either oil-extended or non-oil-extended SBR can be used. In this specification, commercially available SBRs from JSR Corporation, Sumitomo Chemical Co., Ltd., UBE Corporation, Asahi Kasei Corporation, ZS Elastomers Co., Ltd., ARLANXEO, etc. can be used.

[0073] The content of SBR in the rubber component is preferably more than 15% by mass, more preferably more than 25% by mass, and even more preferably more than 35% by mass, and is preferably less than 80% by mass, more preferably less than 70% by mass, even more preferably less than 60% by mass, and even more preferably less than 50% by mass.

[0074] (Isoprene rubber) Examples of isoprene-based rubbers that can be used include those commonly used in the tire industry, such as isoprene rubber (IR) and natural rubber. Natural rubber includes unmodified natural rubber (NR) as well as modified natural rubbers such as epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), deproteinized natural rubber (DPNR), highly purified natural rubber, and grafted natural rubber. These isoprene-based rubbers may be used alone or in combination of two or more.

[0075] The NR is not particularly limited, and those commonly used in the tire industry can be used, such as SVR-1, SIR20, RSS#3, and TSR20.

[0076] The content of the isoprene-based rubber in the rubber component is preferably more than 15% by mass, more preferably more than 25% by mass, and even more preferably more than 35% by mass, and the content of the SBR in the rubber component is preferably less than 80% by mass, more preferably less than 70% by mass, even more preferably less than 60% by mass, and even more preferably less than 50% by mass.

[0077] (BR) The BR is not particularly limited, and can be one commonly used in the tire industry, such as BR with a cis content of less than 50 mol% (low-cis BR), BR with a cis content of 90 mol% or more (high-cis BR), rare earth butadiene rubber (rare earth BR) synthesized using a rare earth catalyst, BR containing syndiotactic polybutadiene crystals (SPB-containing BR), or modified BR (high-cis modified BR, low-cis modified BR). Of these, high-cis BR is preferred. These BRs may be used alone or in combination of two or more.

[0078] As the high-cis BR, for example, commercially available products from Zeon Corporation, UBE Corporation, JSR Corporation, etc. can be used. The inclusion of high-cis BR can improve low-temperature properties and wear resistance. The cis content of the high-cis BR is preferably more than 90 mol%, more preferably more than 93 mol%, and even more preferably 95 mol% or more. The cis content of BR is measured by the above-mentioned measurement method.

[0079] The rare earth BR is synthesized using a rare earth catalyst and has a vinyl content of preferably less than 1.8 mol%, more preferably less than 1.6 mol%, and even more preferably 1.5 mol% or less, and a cis content of preferably more than 95 mol%, more preferably more than 96 mol%, even more preferably more than 97 mol%, and even more preferably 98 mol% or more. As the rare earth BR, for example, commercially available products from Lanxess K.K. can be used.

[0080] The SPB-containing BR is not simply 1,2-syndiotactic polybutadiene crystals dispersed in the BR, but is dispersed after being chemically bonded to the BR. As such SPB-containing BR, commercially available products from UBE Corporation and the like can be used.

[0081] Examples of modified BR include BR modified with functional groups similar to those described above for SBR, and also preferably used are modified butadiene rubbers (modified BRs) whose terminals and / or main chains are modified with functional groups containing at least one element selected from the group consisting of silicon, nitrogen, and oxygen.

[0082] Other examples of modified BR include tin-modified BR, which is obtained by polymerizing 1,3-butadiene with a lithium initiator and then adding a tin compound, and in which the terminals of the modified BR molecule are further bonded with a tin-carbon bond (tin-modified BR).Modified BR may be either non-hydrogenated or hydrogenated.

[0083] From the viewpoint of abrasion resistance, the weight-average molecular weight (Mw) of BR is preferably more than 200,000, more preferably more than 300,000, and even more preferably more than 400,000. From the viewpoint of crosslinking uniformity, etc., it is preferably less than 2,000,000, more preferably less than 1,000,000, and even more preferably less than 800,000. Mw can be determined by the above-mentioned method.

[0084] The content of BR in the rubber component is not particularly limited, but is preferably more than 1% by mass, more preferably more than 5% by mass, and even more preferably more than 10% by mass. The content of BR in the rubber component is also preferably less than 50% by mass, more preferably less than 30% by mass, and even more preferably less than 25% by mass.

[0085] (Rubber components synthesized from recycled and biomass-derived raw materials) Monomers, which are structural units of synthetic rubbers such as SBR and BR, may be derived from petroleum or 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 thereof include recycled butadiene and recycled aromatic vinyl compounds. Examples of butadienes include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyl compounds are not particularly limited, and examples thereof include styrene. Among these, it is preferable to use recycled butadiene (recycled butadiene) and / or recycled styrene (recycled styrene) as raw materials.

[0086] 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.

[0087] Furthermore, monomers that are structural units of polymers such as SBR and BR may be derived from biomass. Examples of biomass-derived monomers (biomass monomers) include, but are not limited to, biomass-derived butadienes 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. Furthermore, methods for producing biomass monomers are not particularly limited and include, for example, biological and / or chemical and / or physical conversion of animals and plants. A typical example of biological conversion is fermentation by microorganisms, while examples of chemical and / or physical conversion include catalytic, high-temperature, high-pressure, electromagnetic, and critical fluid conversion, as well as combinations thereof. Biomass sources for these monomers include sugar, wood, plant residues after useful components have been extracted, plant-derived ethanol, and biomass naphtha.

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

[0089] Whether a polymer's raw material is biomass-derived can be determined by its pMC (percent modern carbon) measured in accordance with ASTM D6866-10. pMC is the modern standard reference carbon. 14 of sample against C concentration 14 This is the ratio of the carbon concentration, and this value is used as an index showing the biomass ratio of the compound (rubber). The significance of this value is explained below.

[0090] 1 mole of carbon atoms (6.02 × 10 23 ) contains approximately 6.02 × 10 atoms, which is about one trillionth of the number of ordinary carbon atoms. 11 pieces 14 C exists. 14 The half-life of C is 5730 years, 14 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, carbon dioxide was included in these when they were first fixed. 14 All C elements have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas contain 14 Therefore, chemicals produced from these fossil fuels do not contain any C element. 14 It does not contain any C element.

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

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

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

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

[0095] When the rubber component is composed of only three rubbers, i.e., IR rubber, SBR, and BR, if the contents of any two of the rubber components are determined based on the above explanation, the content of the remaining rubber component is naturally determined so that the total rubber component is 100% by mass.

[0096] <Filler> The rubber composition according to the present embodiment contains silica as a filler. Fillers other than silica may be contained, and examples of such fillers include carbon black and fillers other than silica and carbon black. The other fillers are not particularly limited, but examples include those commonly used in the tire industry, such as aluminum hydroxide, calcium carbonate, alumina, clay, and talc. The fillers other than silica may be used alone or in combination of two or more.

[0097] The filler preferably contains carbon black in addition to silica, and may consist of only silica and carbon black.

[0098] (silica) The silica is not particularly limited, and can be, for example, silica prepared by a dry method (anhydrous silica), silica prepared by a wet method (hydrated silica), or other silica commonly used in the tire industry. The raw material for silica is also not particularly limited, and can be, for example, a mineral-derived raw material such as quartz, a biological raw material such as rice husk (for example, silica made from biomass materials such as rice husk), or silica recycled from silica-containing products. Among these, hydrated silica prepared by a wet method is preferred because it contains a large number of silanol groups. These silicas can be used alone or in combination of two or more types.

[0099] 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.

[0100] 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.

[0101] When silica crystallizes, it becomes insoluble in water, and its component, silicic acid, cannot be utilized. By controlling the combustion temperature and duration, the crystallization of silica in rice husk ash can be suppressed (see, for example, JP 2009-2594 A, Akita Prefectural University Web Journal B / 2019, vol. 6, pp. 216-222). Amorphous silica extracted from rice husks can be commercially available from Wilmar, Inc.

[0102] The nitrogen adsorption specific surface area (N2SA) of silica is 100m from the viewpoint of ensuring reinforcement and grip performance. 2 / g or more is preferable, and 120m 2 / g is more preferable, and 140m 2 / g or more is more preferable, and 160m 2 / g or more is more preferable, and 170m 2 From the viewpoint of heat buildup and processability, it is particularly preferable that the tensile strength is more than 350 m / g. 2 / g is preferable, and 300m 2 / g is more preferable, and 250m 2 / g or less is more preferable. The N2SA of silica is measured by the above-mentioned measurement method.

[0103] The average primary particle size 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.The average primary particle size is preferably less than 24 nm, more preferably less than 22 nm, and even more preferably less than 20 nm.The average primary particle size of silica is measured by the above-mentioned measurement method.

[0104] From the viewpoint of the effects of the present invention, the content of silica per 100 parts by mass of the rubber component is preferably more than 30 parts by mass, more preferably more than 40 parts by mass, and even more preferably more than 50 parts by mass. Also, from the viewpoint of processability, the content of silica per 100 parts by mass of the rubber component is preferably less than 200 parts by mass, more preferably less than 150 parts by mass, and even more preferably less than 100 parts by mass.

[0105] (Silane coupling agent) Silica is preferably used in combination with a silane coupling agent.Silane coupling agent is not particularly limited, but for example, sulfide-based silane coupling agent such as bis(3-triethoxysilylpropyl) disulfide, bis(3-triethoxysilylpropyl) tetrasulfide; mercapto-based silane coupling agent such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane; vinyl-based silane coupling agent such as vinyltriethoxysilane, vinyltrimethoxysilane; 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane Examples of suitable silane coupling agents include amino-based silane coupling agents such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based silane coupling agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based silane coupling agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Among these, sulfide-based silane coupling agents and / or mercapto-based silane coupling agents are preferred. Examples of suitable silane coupling agents include those commercially available from Evonik Degussa GmbH and Momentive GmbH. These silane coupling agents may be used alone or in combination.

[0106] The content of the silane coupling agent is preferably more than 3 parts by mass, more preferably more than 5 parts by mass, and even more preferably more than 8 parts by mass relative to 100 parts by mass of silica from the viewpoint of improving the dispersibility of silica, and from the viewpoint of cost and processability, it is preferably less than 20 parts by mass, more preferably less than 15 parts by mass, and even more preferably less than 12 parts by mass.

[0107] (carbon black) Carbon black is not particularly limited, and examples thereof include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. The raw material for carbon black may be a biomass material such as lignin or vegetable oil, or pyrolysis oil obtained by pyrolysis of waste tires. Carbon black may be produced by combustion, such as in a furnace process, by hydrothermal carbonization (HTC), or by thermal decomposition of methane, such as in a thermal black process. Commercially available carbon black products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Nippon Steel Carbon Co., Ltd., and Columbia Carbon Co., Ltd. Carbon black may be used alone or in combination.

[0108] In addition to the above, from the viewpoint of life cycle assessment, carbon black may be made from a biomass material such as lignin, or recycled carbon black obtained by pyrolysis and purification of a product containing carbon black, such as a tire.

[0109] As used herein, "recycled carbon black" refers to carbon black obtained by crushing used tires or other products containing carbon black and calcining the crushed material, and refers to carbon black in which, when subjected to oxidative combustion by heating in air as measured by thermogravimetry in accordance with JIS K 6226-2:2003, the proportion of the mass of ash (ash content), which is the non-combustible component, is 13% by mass or more. In other words, the proportion of the mass (carbon content) of the recycled carbon black lost due to oxidative combustion is 87% by mass or less. Recycled carbon black is sometimes expressed as rCB.

[0110] Recycled carbon black can be obtained from the pyrolysis process of used pneumatic tires. For example, European Patent Application Publication No. 3427975, citing "Rubber Chemistry and Technology," Vol. 85, No. 3, pp. 408-449 (2012), particularly pp. 438, 440, and 442, describes the carbon black as being obtained by pyrolysis of organic materials at 550-800°C in the absence of oxygen, or by vacuum pyrolysis at relatively low temperatures (

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

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

[0111] Recycled carbon black may lack functional groups on its surface, or may be treated to include functional groups on its surface. Treatment to include functional groups on the surface of recycled carbon black can be carried out by conventional methods. For example, European Patent Application Publication No. 3,173,251 discloses treating carbon black obtained from a pyrolysis process with potassium permanganate under acidic conditions to obtain carbon black containing hydroxyl and / or carboxyl groups on its surface. Furthermore, Japanese Patent No. 6,856,781 discloses treating carbon black obtained from a pyrolysis process with an amino acid compound containing at least one thiol or disulfide group to obtain surface-activated carbon black. The recycled carbon black of this embodiment also includes carbon blacks that have been treated to include functional groups on their surfaces.

[0112] As the recycled carbon black, commercially available products from Strable Green Carbon, LD Carbon, etc. can be used.

[0113] The average primary particle diameter of carbon black is preferably 15 nm or more, more preferably 18 nm or more, and even more preferably 20 nm or more. On the other hand, from the viewpoint of obtaining reinforcing properties, the average primary particle diameter is preferably 100 nm or less, more preferably 80 nm or less, and even more preferably 50 nm or less. The average primary particle diameter of carbon black is measured by the above-mentioned measurement method.

[0114] From the viewpoint of the effect of the present invention, the nitrogen adsorption specific surface area (N2SA) of carbon black is 200 m 2 / g or less is preferred, and 180m 2 / g is more preferable, and 150m 2 / g or less is more preferable. 2 / g or more is preferable, and 50m 2 / g is more preferable, and 70m 2 The N2SA of carbon black is measured by the above-mentioned measurement method.

[0115] The amount of carbon black per 100 parts by mass of the rubber component is preferably more than 2 parts by mass, more preferably more than 4 parts by mass, and even more preferably 5 parts by mass or more, from the viewpoint of reinforcement, and is preferably less than 50 parts by mass, more preferably less than 30 parts by mass, and even more preferably less than 20 parts by mass, from the viewpoint of the effects of the present invention.

[0116] (A SIL / A CB ) The content (parts by mass) of the silica relative to 100 parts by mass of the rubber component is A SIL The content (parts by mass) of the carbon black relative to 100 parts by mass of the rubber component is A CB In the case where A SIL / A CB is preferably greater than 1.0. SIL / A CB is more preferably greater than 2.0, even more preferably greater than 5.0, even more preferably greater than 10.0, and even more preferably greater than 13.0. SIL / A CB There is no particular upper limit to the amount of carbon black, and carbon black may not be contained.

[0117] <Copolymer resin> The rubber composition according to the present embodiment contains a copolymer resin containing styrene and dicyclopentadiene as monomer components (hereinafter simply referred to as "copolymer resin").

[0118] The copolymer resin is not particularly limited as long as it contains dicyclopentadiene and styrene as monomer components, and may further contain other monomer components. Also, it may be a hydrogenated or modified version of these monomer components.

[0119] The other monomer components are not particularly limited, but are preferably monomer components commonly used in petroleum resins, such as C9 fractions. Examples of C9 fractions include petroleum fractions having 8 to 10 carbon atoms, selected from the group consisting of alkylstyrenes such as vinyltoluene, coumarone, indene, and methylindene. Among these C9 fractions, indene is preferred.

[0120] The copolymer resin is preferably, for example, a copolymer resin containing dicyclopentadiene, styrene, and indene as monomer components, and may be a hydrogenated or modified copolymer resin.

[0121] As the copolymer resin containing dicyclopentadiene and styrene as monomer components, commercially available products from, for example, ExxonMobil Corporation, ENEOS Corporation, Zeon Corporation, Maruzen Petrochemical Co., Ltd., etc. may be used. One copolymer resin may be used alone, or two or more copolymer resins may be used in combination.

[0122] From the viewpoint of the effects of the present invention, the styrene content of the copolymer resin is preferably 0.5% by mass or more, more preferably 0.8% by mass or more, and even more preferably 1.0% by mass or more. The upper limit of the styrene content is not particularly limited, and may be, for example, less than 50% by mass, less than 25% by mass, less than 10% by mass, 5% by mass or less, 3% by mass or less, or 2% by mass or less.

[0123] From the viewpoint of the effects of the present invention, the softening point of the copolymer resin is preferably above 70° C., more preferably above 80° C., even more preferably above 90° C., and particularly preferably above 100° C. Furthermore, from the viewpoint of improving processability and dispersibility of the rubber component and the filler, the softening point is preferably below 150° C., more preferably below 140° C., and even more preferably below 130° C. The softening point of the resin is measured by the above-mentioned measurement method.

[0124] The content of the copolymer resin (total content when two or more types are contained) per 100 parts by mass of the rubber component is preferably more than 3 parts by mass, more preferably more than 5 parts by mass, and even more preferably 10 parts by mass or more. On the other hand, from the viewpoint of suppressing heat buildup, the content is preferably less than 80 parts by mass, more preferably less than 60 parts by mass, and even more preferably less than 40 parts by mass.

[0125] <Total styrene content St> The total styrene amount St (mass%) is not particularly limited in the present embodiment as long as it satisfies the above formula (1) and formula (2). Generally, St is preferably 2.00 mass% or more, more preferably 4.00 mass% or more, and even more preferably 5.00 mass% or more, and on the other hand, is preferably 25.00 mass% or less, more preferably 20.00 mass% or less, and even more preferably 15.00 mass% or less.

[0126] <Other compounding agents> In addition to the above components, the rubber composition according to the present embodiment may contain, as appropriate, compounding agents that are generally used in the tire industry, such as softeners, processing aids, vulcanized rubber particles, wax, stearic acid, zinc oxide, antioxidants, vulcanizing agents, and vulcanization accelerators.

[0127] (softener) The softener is as described above, and specific examples include resins, oils, liquid polymers, and ester-based plasticizers. These softeners may be derived from petroleum, biomass, or naphtha recycled from rubber or 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 softeners. One type of softener may be used alone, or two or more types may be used in combination.

[0128] The rubber composition preferably contains 30 to 70 parts by mass of a softener per 100 parts by mass of the rubber component. The content of the softener is more preferably 35 parts by mass or more, and even more preferably 40 parts by mass or more. On the other hand, the content of the softener is more preferably 65 parts by mass or less, and even more preferably 60 parts by mass or less.

[0129] <Resin> The rubber composition according to the present embodiment may contain other resins in addition to the copolymer resin. The other resins are not particularly limited, but resins commonly used in the tire industry can be used, such as aromatic vinyl resins, dicyclopentadiene resins (DCPD resins), C9 resins, C5 resins, C5C9 resins, terpene resins, rosin resins, and phenolic resins. The other resins may be used alone or in combination of two or more.

[0130] aromatic vinyl resin In this specification, 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 a monomer component (excluding copolymer resins containing dicyclopentadiene and styrene as monomer components). As the aromatic vinyl resin, a homopolymer of α-methylstyrene or styrene or a copolymer of α-methylstyrene and styrene is preferred, and a copolymer of α-methylstyrene and styrene is more preferred, because they are economical, easy to process, and have excellent heat generation properties. As the aromatic vinyl resin, commercially available products from Kraton, Eastman Chemical, Mitsui Chemicals, Inc., etc., can be used. One type of resin may be used alone, or two or more types may be used in combination.

[0131] Dicyclopentadiene Resin In this specification, "dicyclopentadiene-based resin (DCPD resin)" refers to a resin containing dicyclopentadiene (DCPD) as a monomer component (excluding copolymer resins containing dicyclopentadiene and styrene as monomer components). As DCPD resins, for example, those commercially available from ExxonMobil Corporation, ENEOS Corporation, Nippon Zeon Co., Ltd., Maruzen Petrochemical Co., Ltd., etc. can be used. Such resins may be used alone or in combination of two or more.

[0132] C9 resin As used herein, the term "C9 resin" refers to a resin obtained by polymerizing a C9 fraction (excluding copolymer resins containing dicyclopentadiene and styrene as monomer components). It may be a polymer of a C9 fraction alone or a copolymer of a C9 fraction with other components. Examples of C9 fractions include petroleum fractions containing 8 to 10 carbon atoms, selected from the group consisting of alkylstyrenes such as vinyltoluene, coumarone, indene, and methylindene. Specific examples of C9 resins include coumarone-indene resins, coumarone resins, and indene resins. These resins may be used singly or in combination.

[0133] C5 resin In this specification, "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.

[0134] 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. As the C5C9 petroleum resin, for example, commercially available products from Tosoh Corporation, LUHUA, etc. can be used. The resin may be used alone or in combination of two or more.

[0135] Terpene Resin Terpene resins refer to resins containing at least one terpene compound selected from the group consisting of α-pinene, β-pinene, limonene, dipentene, etc., as the most abundant monomer component, preferably at least 50 mol %, and may be hydrogenated or modified. Specific examples of terpene resins include polyterpene resins containing only one or more of the terpene compounds as monomer components; aromatic-modified terpene resins containing the terpene compound and an aromatic compound as monomer components; and terpene phenolic resins containing the terpene compound and a phenolic compound as monomer components. Examples of aromatic compounds that serve as monomer components for aromatic-modified terpene resins include at least one selected from the group consisting of styrene, α-methylstyrene, vinyltoluene, divinyltoluene, etc. Examples of phenolic compounds that serve as monomer components for terpene phenolic resins include at least one selected from the group consisting of phenol, bisphenol A, cresol, xylenol, etc. These resins may be used alone or in combination.

[0136] 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., and may be a hydrogenated or modified version of such a rosin-based resin. Examples of the rosin-based resin include, but are not limited to, natural rosin and rosin-modified resins obtained by modifying rosin through hydrogenation, disproportionation, dimerization, esterification, etc. Such resins may be used singly or in combination of two or more.

[0137] 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.

[0138] ≪Softening point≫ From the viewpoint of wet grip performance, the softening point of the other resin is preferably above 80° C., more preferably above 90° C., and even more preferably above 100° C. Furthermore, from the viewpoint of processability and improving the dispersibility of the rubber component and the filler, the softening point is preferably below 150° C., more preferably below 140° C., and even more preferably below 130° C. The softening point of the other resin is measured by the above-mentioned measurement method.

[0139] ≪Content≫ The content of the other resins (total content when two or more types are contained) per 100 parts by mass of the rubber component is preferably more than 10 parts by mass, more preferably more than 15 parts by mass, and even more preferably 20 parts by mass or more. On the other hand, from the viewpoint of suppressing heat buildup, the content is preferably less than 80 parts by mass, more preferably less than 60 parts by mass, even more preferably less than 40 parts by mass, and even more preferably less than 20 parts by mass, or may not be contained.

[0140] <Oil> Examples of oils include process oil, vegetable oil, and animal oil. Examples of process oils include paraffinic process oil (mineral oil), naphthenic process oil, and aromatic process oil. Specific examples of process oils include mild extracted solvate (MES), distillate aromatic extract (DAE), treated distillate aromatic extract (TDAE), treated residual aromatic extract (TRAE), and residual aromatic extract (RAE). Furthermore, as an environmental measure, process oils with a low content of polycyclic aromatic compounds (PCA) can also be used. Examples of low-PCA process oils include MES, TDAE, and heavy naphthenic oil. Furthermore, from the perspective of life cycle assessment, refined waste oil from rubber mixers and engines, or waste cooking oil from restaurants, may also be used. One type of oil may be used alone, or two or more types may be used in combination.

[0141] Examples of vegetable oils include linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar oil, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grapeseed oil, and Japan wax. Further examples of vegetable oils include refined oils (such as salad oil) obtained by refining the above oils, interesterified oils obtained by interesterifying the above oils, hardened oils obtained by hydrogenating the above oils, thermally polymerized oils obtained by thermally polymerizing the above oils, oxidatively polymerized oils obtained by oxidizing the above oils, and waste edible oils recovered from edible oils. Vegetable oils may be liquid or solid at room temperature (25°C).

[0142] The vegetable oil preferably contains acylglycerol, and more preferably triacylglycerol. In this specification, acylglycerol refers to a compound in which a hydroxyl group of glycerin is ester-bonded to a fatty acid. The acylglycerol is not particularly limited and may be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Furthermore, the acylglycerol may be a monomer, a dimer, or a polymer (trimer or higher). Dimer or higher acylglycerols can be obtained by thermal polymerization, oxidative polymerization, or the like. Furthermore, the acylglycerol may be liquid or solid at room temperature (25°C).

[0143] The method for confirming whether the rubber composition contains the acylglycerol is not particularly limited, but may be any of the following: 1 For example, a rubber composition containing triacylglycerol is immersed in deuterated chloroform at room temperature (25°C) for 24 hours, and after removing the rubber composition, the rubber composition is immersed in deuterated chloroform at room temperature. 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.

[0144] 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.

[0145] 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.

[0146] 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.

[0147] Examples of animal oils include fish oil, beef tallow, whale oil, and oleyl alcohol derived from these.

[0148] When oil is contained, the content per 100 parts by mass of the rubber component is preferably 8 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 20 parts by mass or more from the viewpoint of processability. Also, from the viewpoint of abrasion resistance, the content is preferably 80 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 40 parts by mass or less. The oil content includes the amount of oil contained in the oil-extended rubber.

[0149] <Liquid rubber> The liquid rubber is not particularly limited as long as it is a polymer that is in a liquid state at room temperature (25°C), and examples thereof include liquid butadiene rubber (liquid BR), liquid styrene butadiene rubber (liquid SBR), liquid isoprene rubber (liquid IR), liquid styrene isoprene rubber (liquid SIR), liquid farnesene rubber, etc. One type of liquid rubber may be used alone, or two or more types may be used in combination.

[0150] When liquid rubber is contained, the content per 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more. The content of liquid rubber is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 10 parts by mass or less. The content of liquid rubber includes the amount of extended liquid rubber used to extend the rubber component.

[0151] <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.

[0152] When an ester plasticizer is contained, the content per 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more. The content of the liquid rubber is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 10 parts by mass or less. The content of the ester plasticizer includes the amount of the extending ester plasticizer used to extend the rubber component.

[0153] (vulcanized rubber particles) The vulcanized rubber particles are particles made of vulcanized rubber, and specifically, rubber powder as specified in JIS K 6316:2017 can be used. From the standpoint of environmental considerations and cost, recycled rubber powder produced from crushed waste tires is preferred. One type of vulcanized rubber particle may be used alone, or two or more types may be used in combination.

[0154] The vulcanized rubber particles are not particularly limited, and may be unmodified or modified. Commercially available vulcanized rubber products include those from Lehigh Industries, Muraoka Rubber Industries, and the like.

[0155] When vulcanized rubber particles are contained, the content thereof relative to 100 parts by mass of the rubber component can be appropriately adjusted, for example, within the range of more than 1 part by mass and less than 80 parts by mass.

[0156] (stearic acid) When stearic acid is contained, the content per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, from the viewpoint of processability, and is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, from the viewpoint of vulcanization rate.

[0157] (zinc oxide) When zinc oxide is contained, the content per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1.0 parts by mass or more, and even more preferably 1.5 parts by mass or more from the viewpoint of processability, and is preferably 5.0 parts by mass or less, more preferably 4.5 parts by mass or less, and even more preferably 4.0 parts by mass or less from the viewpoint of abrasion resistance.

[0158] (wax) The wax is not particularly limited, and any wax commonly used in the tire industry can be suitably used. Examples include petroleum-based waxes, mineral-based waxes, synthetic waxes, and plant-derived waxes. Of these, petroleum-based waxes and plant-derived waxes are preferred, and petroleum-based waxes are more preferred. Examples of plant-derived waxes include rice wax, carnauba wax, and candelilla wax. Examples of petroleum-based 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 that can be used include those commercially available from, for example, Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Paramelt Co., Ltd. One type of wax may be used alone, or two or more types may be used in combination.

[0159] When wax is contained, the content per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, from the viewpoint of weather resistance of the rubber, and is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, from the viewpoint of preventing whitening of the tire due to bloom.

[0160] (anti-aging agent) The antioxidant is not particularly limited, and 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 antioxidants such as N-isopropyl-N'-phenyl-p-phenylenediamine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline antioxidants such as 2,2,4-trimethyl-1,2-dihydroquinoline polymers; monophenol antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol 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.

[0161] When an antioxidant is contained, the content per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, from the viewpoint of ozone crack resistance of the rubber, and is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, from the viewpoint of abrasion resistance and wet grip performance.

[0162] (processing aids) Examples of processing aids include fatty acid metal salts, fatty acid amides, amide esters, silica surfactants, fatty acid esters, 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.

[0163] When a processing aid is contained, the content thereof per 100 parts by mass of the rubber component is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, from the viewpoint of improving processability, and is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 5 parts by mass or less, from the viewpoint of abrasion resistance and breaking strength.

[0164] (vulcanizing agent) Sulfur is preferably used as the vulcanizing agent. Examples of sulfur that can be used include powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersible sulfur. The vulcanizing agent may be used alone or in combination of two or more.

[0165] When sulfur is contained as a vulcanizing agent, the content per 100 parts by mass of the rubber component is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and even more preferably 0.5 parts by mass or more, from the viewpoint of ensuring a sufficient vulcanization reaction. Furthermore, from the viewpoint of preventing deterioration, the content is preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, and even more preferably 3.0 parts by mass or less. When oil-containing sulfur is used as the vulcanizing agent, the content of the vulcanizing agent is the total content of pure sulfur contained in the oil-containing sulfur.

[0166] Examples of vulcanizing agents other than sulfur include alkylphenol-sulfur chloride condensate, sodium 1,6-hexamethylenedithiosulfate dihydrate, 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane, etc. These vulcanizing agents other than sulfur can be commercially available from Taoka Chemical Co., Ltd., Lanxess K.K., Flexis, etc.

[0167] (Vulcanization accelerator) Examples of vulcanization accelerators 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, sulfenamide-based, thiazole-based, and guanidine-based vulcanization accelerators are preferred. One type of vulcanization accelerator may be used alone, or two or more types may be used in combination.

[0168] Examples of sulfenamide vulcanization accelerators include N-tert-butyl-2-benzothiazolylsulfenamide (TBBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N,N-dicyclohexyl-2-benzothiazolylsulfenamide (DCBS), etc. Among these, N-cyclohexyl-2-benzothiazolylsulfenamide (CBS) is preferred.

[0169] Examples of the thiazole vulcanization accelerator include 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, etc. Among these, 2-mercaptobenzothiazole is preferred.

[0170] Examples of guanidine vulcanization accelerators include 1,3-diphenylguanidine (DPG), 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, di-o-tolylguanidine salt of dicatechol borate, 1,3-di-o-cumenylguanidine, 1,3-di-o-biphenylguanidine, 1,3-di-o-cumenyl-2-propionylguanidine, etc. Among these, 1,3-diphenylguanidine (DPG) is preferred.

[0171] When a vulcanization accelerator is contained, the content thereof per 100 parts by mass of the rubber component is preferably 1 part by mass or more, more preferably 1.5 parts by mass or more. The content thereof per 100 parts by mass of the rubber component is preferably 8 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 6 parts by mass or less. By setting the content of the vulcanization accelerator within the above range, breaking strength and elongation tend to be ensured.

[0172] <Various materials containing carbon atoms> In this specification, various materials containing carbon atoms (for example, rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from atmospheric carbon dioxide. The various materials may be obtained from carbon dioxide by directly converting carbon dioxide or by converting methane obtained through a methanation process in which methane is synthesized from carbon dioxide.

[0173] [Manufacturing method] The rubber composition can be produced by a known method, for example, by kneading the above-mentioned components using a rubber kneading device such as an open roll or an internal kneader (such as a Banbury mixer or kneader).

[0174] The kneading step includes, for example, a base kneading step in which compounding ingredients and additives other than the vulcanizing agent and vulcanization accelerator are kneaded, and a final kneading (F kneading) step in which the vulcanizing agent and vulcanization accelerator are added to the kneaded product obtained in the base kneading step and kneaded. Furthermore, the base kneading step can be divided into multiple steps as desired.

[0175] The kneading conditions are not particularly limited, but examples include a method in which the base kneading step involves kneading for 3 to 10 minutes at a discharge temperature of 150 to 170°C, and in the final kneading step, kneading for 1 to 5 minutes at 70 to 110°C.

[0176] The tire according to the present embodiment can be manufactured by a conventional method using the rubber composition. That is, the unvulcanized rubber composition is extruded in an extruder equipped with a die of a predetermined shape to match the shape of the rubber layer that constitutes the tread contact surface, and then the extruded rubber composition is bonded together with other tire components in a tire building machine while adjusting the structure to obtain a predetermined tire structure, and molded by a conventional method to form an unvulcanized tire. The unvulcanized tire is then heated and pressurized in a vulcanizer, whereby the tire can be manufactured. The vulcanization conditions are not particularly limited, and examples thereof include a method of vulcanizing at 140 to 170°C for 10 to 40 minutes.

[0177] [Application] In this specification, the term "tire" refers to a tire that can be used for any purpose, regardless of whether it is a pneumatic tire or a non-pneumatic tire, and can be used as a passenger car tire, a large passenger car tire, a large SUV tire, a racing tire, a motorcycle tire, a heavy-duty tire, or a run-flat tire. Passenger car tires are tires designed to be mounted on four-wheeled vehicles and have a maximum load capacity of less than 1,400 kg. Heavy-duty tires are tires with a maximum load capacity of 1,400 kg or more. In this specification, the term "tire" refers to all-season tires, summer tires, and winter tires such as studless tires. [Example]

[0178] Below, examples (working examples) that are considered preferable for implementation are shown, but the scope of the present invention is not limited to these working examples. According to each table, rubber layers including tread contact surfaces obtained using the various chemicals shown below, and tires having tire structures were examined, and the results calculated based on the evaluation methods below are shown at the bottom of each table.

[0179] [Various medicines] The various chemicals used in the examples and comparative examples are listed below. NR:TSR20 SBR1: SBR produced by Production Example 1 below (styrene content: 29% by mass, vinyl content: 25% by mole, Tg: -43°C, Mw: 450,000, non-oil extended) SBR2: SBR produced by Production Example 2 below (styrene content: 24% by mass, vinyl content: 22% by mole, Tg: -53°C, Mw: 450,000, non-oil extended) SBR3: SBR produced by Production Example 3 below (styrene content: 19% by mass, vinyl content: 18% by mole, Tg: −62° C., Mw: 470,000, non-oil extended) SBR4: SBR produced by Production Example 4 below (styrene content: 13% by mass, vinyl content: 20% by mole, Tg: −71° C., Mw: 420,000, non-oil extended) BR: BR730 (cis content: 95 mol%) manufactured by ENEOS Materials Corporation Silica: Ultrasil VN3 (N2SA: 175 ml) manufactured by Evonik Degussa 2 / g, average primary particle diameter: 18nm) CB (carbon black): Diablack I (N220, N2SA: 114m) manufactured by Mitsubishi Chemical Corporation 2 / g, average primary particle diameter: 22nm) Coupling agent (silane coupling agent): Si266 (bis(3-triethoxysilylpropyl) disulfide) manufactured by Evonik Degussa Resin 1: Oppa PR383 manufactured by ExxonMobil Corporation (a copolymer resin containing dicyclopentadiene, styrene, and indene as monomer components, Mw: 770, softening point: 103°C, styrene content: 1.78% by mass) Resin 2: YS Polyster T115 (terpene phenol resin, softening point: 115±5°C) manufactured by Yasuhara Chemical Co., Ltd. Oil: Diana Process NH-70S manufactured by Idemitsu Kosan Co., Ltd. Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. Antioxidant: Nocrac 6C (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Stearic acid: Camellia stearic acid beads manufactured by NOF Corporation Wax: Ozoace 0355 (paraffin wax) manufactured by Nippon Seiro Co., Ltd. Sulfur: 5% oil-treated powder sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. Vulcanization accelerator 1: Noccelaer D (1,3-diphenylguanidine (DPG)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd. Vulcanization accelerator 2: Noccela CZ (N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS)) manufactured by Ouchi Shinko Chemical Industry Co., Ltd.

[0180] Manufacturing Example 1: Manufacturing of SBR1 Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene are charged into a nitrogen-purged autoclave reactor. The ratio of styrene to 1,3-butadiene is adjusted so that the styrene content is 29% by mass. After adjusting the temperature of the reactor contents to 20°C, n-butyllithium is added to initiate polymerization. Polymerization occurs under adiabatic conditions, reaching a maximum temperature of 80°C. After confirming the formation of a polymer with a Mw of 450,000 by GPC, the polymerization solution is poured into 4 L of ethanol and the precipitate is recovered. The resulting precipitate is blown dry and then vacuum dried at 80°C / 10 Pa or less until the loss on drying is 0.1%, yielding SBR1.

[0181] Manufacturing Example 2: Manufacturing of SBR2 Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene are charged into a nitrogen-purged autoclave reactor. The ratio of styrene to 1,3-butadiene is adjusted so that the styrene content is 24% by mass. After adjusting the temperature of the reactor contents to 20°C, n-butyllithium is added to initiate polymerization. Polymerization occurs under adiabatic conditions, reaching a maximum temperature of 80°C. After confirming the formation of a polymer with a Mw of 450,000 by GPC, the polymerization solution is poured into 4 L of ethanol and the precipitate is recovered. The resulting precipitate is blown dry and then vacuum dried at 80°C / 10 Pa or less until the loss on drying is 0.1%, yielding SBR2.

[0182] Manufacturing Example 3: Manufacturing of SBR3 Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene are charged into a nitrogen-purged autoclave reactor. The ratio of styrene to 1,3-butadiene is adjusted so that the styrene content is 19% by mass. After adjusting the temperature of the reactor contents to 20°C, n-butyllithium is added to initiate polymerization. Polymerization occurs under adiabatic conditions, reaching a maximum temperature of 80°C. After confirming the formation of a polymer with a Mw of 470,000 by GPC, the polymerization solution is poured into 4 L of ethanol and the precipitate is recovered. The resulting precipitate is blown dry and then vacuum dried at 80°C / 10 Pa or less until the loss on drying is 0.1%, yielding SBR3.

[0183] Manufacturing Example 4: Manufacturing of SBR4 Cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene are charged into a nitrogen-purged autoclave reactor. The ratio of styrene to 1,3-butadiene is adjusted so that the styrene content is 13% by mass. After adjusting the temperature of the reactor contents to 20°C, n-butyllithium is added to initiate polymerization. Polymerization occurs under adiabatic conditions, reaching a maximum temperature of 80°C. After confirming the formation of a polymer with a Mw of 420,000 by GPC, the polymerization solution is poured into 4 L of ethanol and the precipitate is recovered. The resulting precipitate is blown dry and then vacuum dried at 80°C / 10 Pa or less until the loss on drying is 0.1%, yielding SBR4.

[0184] [Examples and Comparative Examples] Tires were manufactured according to the tire structure and compounding recipes shown in each table. First, using a 1.7 L closed-type Banbury mixer, all chemicals except sulfur and vulcanization accelerators were mixed for 1 to 10 minutes until the discharge temperature reached 150 to 160°C, yielding a kneaded mixture. Next, using a two-screw open roll, sulfur and vulcanization accelerators were added to the resulting mixture, and the mixture was mixed for 4 minutes until the temperature reached 105°C, yielding an unvulcanized rubber composition. The resulting unvulcanized rubber composition was extruded using an extruder equipped with a predetermined die to match the shape of the rubber layer including the tread contact surface, and then bonded together with other tire components to produce an unvulcanized tire. The resulting unvulcanized tire was press-vulcanized for 35 minutes at 150°C to produce each test tire (tire size: 195 / 65R15). The tread contact surface had three circumferential main grooves: a linear circumferential main groove passing along the tire centerline and a pair of outermost main grooves narrower than the linear circumferential main groove.

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

[0186] <Grip performance on ice> Each test tire was mounted on each of the four wheels of a 2000cc front-wheel drive passenger vehicle, and the braking distance was measured from the point where the brakes were applied at a speed of 15 km / h on an icy road. The reciprocal value of the braking distance was indexed, with the braking distance of the reference comparative example (Comparative Example 1) set at 100, and the evaluation results for each test tire were displayed. The higher the index, the better the grip performance on ice.

[0187] [Table 1]

[0188] [Embodiment] Examples of embodiments of the present invention are given below.

[0189] [1] A tire having a tread portion having at least one block land portion, The block land portion has a sipe, The density Ds (1 / mm) of the width direction component of the sipe in the tire circumferential direction is 0.15 or more, the rubber layer constituting the tread ground contact surface of the tread portion is made of a rubber composition containing a rubber component including styrene-butadiene rubber, silica, and a copolymer resin containing styrene and dicyclopentadiene as monomer components; A tire in which, when the mass of the rubber component is 100 mass%, the total amount of styrene (mass%) in the rubber composition is St, St and Ds satisfy the following formula (1), and preferably the value of the right side of formula (1) is 0.80. (1) St × Ds > 0.50 [2] The content (mass%) of the styrene butadiene rubber in the rubber component is A SBR If A SBR The tire according to the above [1], wherein and St satisfy the following formula (2): (2) St / A SBR ×100<25.0 [3] The tire according to [1] or [2] above, wherein the right-hand side of formula (1) is 0.82. [4] The tire according to the above [1] or [2], wherein the right side of formula (1) is 1.00, preferably 1.10, more preferably 1.45, even more preferably 1.70, and still more preferably 1.78. [5] The tire according to any one of the above [2] to [4], wherein the right-hand side of formula (2) is 20.0. [6] The tire according to any one of the above [2] to [4], wherein the right-hand side of formula (2) is 15.0, preferably 14.0, and more preferably 13.5. [7] The tire according to any one of the above [1] to [6], wherein the rubber component contains at least one rubber selected from the group consisting of isoprene-based rubbers and butadiene rubbers. [8] The rubber composition contains carbon black, The content (parts by mass) of the silica relative to 100 parts by mass of the rubber component is A SIL The content (parts by mass) of the carbon black relative to 100 parts by mass of the rubber component is A CB If A SIL / A CB The tire according to any one of the above [1] to [7], wherein the value is greater than 1.0, preferably greater than 2.0, more preferably greater than 5.0, even more preferably greater than 10.0, and still more preferably greater than 13.0. [9] The tire according to any one of [1] to [8] above, wherein, when the tire weight is G (kg), St / G is 3.0 or less, preferably 2.5 or less, more preferably 2.0 or less, even more preferably 1.5 or less, even more preferably 1.2 or less, and even more preferably 1.0 or less.

[10] The tread contact surface has three or more circumferential main grooves, The tire according to any one of the above [1] to [9], wherein, when a pair of the circumferential main grooves located at the outermost sides in the tire width direction are outermost circumferential main grooves, the groove width of at least one of the outermost circumferential main grooves is narrower than the groove width of at least one circumferential main groove that is not the outermost circumferential main groove.

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

[10] , wherein the rubber composition contains 30 parts by mass or more and 70 parts by mass or less, preferably 35 parts by mass or more and 65 parts by mass or less, and more preferably 40 parts by mass or more and 60 parts by mass or less of a softener per 100 parts by mass of the rubber component. [Explanation of symbols]

[0190] 11 Sipe 21 Circumferential main groove 22 Outermost circumferential main groove 31 Width groove 32 Width groove Block 41 Land CL Tire centerline (equator) W Tire width direction C Circumferential direction of tire Te tread edge B L Circumferential length of block land area B W Length of block land area in tire width direction< / st>

Claims

1. A tire having a tread portion having at least one block land portion, The block land portion has a sipe, The density Ds (1 / mm) of the width direction component of the sipe in the tire circumferential direction is 0.15 or more, a rubber layer constituting a tread ground contact surface of the tread portion is made of a rubber composition containing a rubber component including styrene-butadiene rubber, silica, and a copolymer resin containing styrene and dicyclopentadiene as monomer components; A tire in which, when the mass of the rubber component is 100 mass%, a total styrene amount (mass%) in the rubber composition is St, St and Ds satisfy the following formula (1): (1) St × Ds > 0.50

2. The content (mass%) of the styrene butadiene rubber in the rubber component is A SBR If A SBR The tire according to claim 1, wherein and St satisfy the following formula (2): (2)St / A SBR ×100<25.0

3. The tire according to claim 1, wherein the right side of formula (1) is 0.

82.

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

00.

5. The tire according to claim 2, wherein the right side of formula (2) is 20.

0.

6. The tire according to claim 2, wherein the right side of formula (2) is 15.

0.

7. The tire according to any one of claims 1 to 6, wherein the rubber component includes at least one rubber selected from the group consisting of an isoprene-based rubber and a butadiene rubber.

8. The rubber composition contains carbon black, The content (parts by mass) of the silica relative to 100 parts by mass of the rubber component is A SIL The content (parts by mass) of the carbon black relative to 100 parts by mass of the rubber component is A CB If A SIL / A CB The tire according to any one of claims 1 to 6, wherein is greater than 1.

0.

9. The tire according to any one of claims 1 to 6, wherein St / G is 3.0 or less when the tire weight is G (kg).

10. The tread contact surface has three or more circumferential main grooves, The tire according to any one of claims 1 to 6, wherein, when a pair of the circumferential main grooves located outermost in the tire width direction are outermost circumferential main grooves, the groove width of at least one of the outermost circumferential main grooves is narrower than the groove width of at least one circumferential main groove that is not the outermost circumferential main groove.

11. The tire according to any one of claims 1 to 6, wherein the rubber composition contains 30 parts by mass or more and 70 parts by mass or less of a softener per 100 parts by mass of the rubber component.

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