tire

Abstract

To further improve the fuel efficiency of tires. [Solution] A tire comprising a carcass formed by winding up a two-layer structure of a first carcass ply and a second carcass ply having carcass cords, a belt having belt cords, a band having band cords containing polyethylene terephthalate fibers, and a tread provided on the radially outer side of the band, formed using a rubber composition containing more than 75 parts by mass of silica per 100 parts by mass of rubber components and more than 15% by mass of acetone extract, wherein the outer diameter Dt (mm), winding height P1 (mm) of the first carcass ply, winding height P2 (mm) of the second carcass ply, diameter D1 (mm) of the band cord, diameter D2 (mm) of the belt cord, and diameter D3 (mm) of the carcass cord satisfy (Equation 1) and (Equation 2). (P1-P2) / Dt<0.07 (Equation 1) (D1+D2+D3)<2.00 (Equation 2)

Description

Technical Field

[0001] The present invention relates to a tire.

Background Art

[0002] In recent years, tires aiming to improve fuel efficiency have been proposed (for example, Patent Documents 1 and 2), but they are still not sufficient.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to further improve the fuel efficiency of a tire.

Means for Solving the Problems

[0005] The present invention is a carcass including a carcass cord, a belt including a belt cord and provided on the outer side in the tire radial direction of the carcass, a band including a band cord and provided on the outer side in the tire radial direction of the belt, a tire including a tread provided on the outer side in the tire radial direction of the band, wherein the carcass has a two-layer structure of a first carcass ply and a second carcass ply each including a carcass cord, and is formed by winding around a bead, the band cord is a band cord containing polyethylene terephthalate fiber, The tread is formed using a rubber composition containing more than 75 parts by mass of silica per 100 parts by mass of rubber component, and more than 15% by mass of acetone extract. Furthermore, when the outer diameter of the tire is Dt (mm), the height of the first carcass ply located on the outside when the carcass is wound up is P1 (mm), and the height of the second carcass ply located on the inside is P2 (mm), the following (Equation 1) is satisfied, The tire is characterized by satisfying the following equation (Equation 2), where D1 (mm) is the diameter of the band cord, D2 (mm) is the diameter of the belt cord, and D3 (mm) is the diameter of the carcass cord. (P1-P2) / Dt<0.07 (Equation 1) (D1+D2+D3)<2.00 (Equation 2) [Effects of the Invention]

[0006] According to the present invention, it is possible to further improve the fuel efficiency of tires. [Brief explanation of the drawing]

[0007] [Figure 1] This diagram illustrates the winding state of the carcass in one embodiment of the present invention. [Figure 2] This is a schematic cross-sectional view illustrating a tire according to one embodiment of the present invention. [Modes for carrying out the invention]

[0008] [1] Features of the tire according to the present invention First, the features of the tire according to the present invention will be described.

[0009] 1. Overview The tire according to the present invention comprises a carcass having carcass cords, a belt having belt cords and provided on the radially outer side of the carcass, a band having band cords and provided on the radially outer side of the belt, and a tread provided on the radially outer side of the band. The carcass has a two-layer structure of a first carcass ply and a second carcass ply, each having carcass cords, and is formed by winding them around the bead core. The band cord is a band cord containing polyethylene terephthalate fibers. The tread is formed using a rubber composition containing more than 75 parts by mass of silica per 100 parts by mass of rubber component and more than 15% by mass of acetone extract. Furthermore, when the outer diameter of the tire is Dt (mm), the winding height of the first carcass ply located on the outside during carcass winding is P1 (mm), and the winding height of the second carcass ply located on the inside is P2 (mm), the following equation (Equation 1) is satisfied, and when the diameter of the band cord is D1 (mm), the diameter of the belt cord is D2 (mm), and the diameter of the carcass cord is D3 (mm), the following equation (Equation 2) is satisfied. (P1-P2) / Dt<0.07 (Equation 1) (D1+D2+D3)<2.00 (Equation 2)

[0010] These features, as will be described later, make it possible to further improve the fuel efficiency of the tires.

[0011] 2. Mechanism of effect in the tire according to the present invention The mechanism by which the above-mentioned effects are manifested in the tire according to the present invention is thought to be as follows.

[0012] (1) Use of PET band In the tire according to the present invention, the band cord is a band cord (PET band) containing polyethylene terephthalate (PET) fibers.

[0013] Because PET fibers have a higher modulus than nylon 66 (polyamide synthetic fiber), which has been primarily used in conventional band cords, it is believed that using PET cords in band cords can suppress heat generation due to the movement of the band layer during operation, thereby further improving fuel efficiency.

[0014] On the other hand, a higher modulus makes the tire profile rounder. As a result, when the tire flexes during driving, the strain tends to concentrate in the sidewall, raising concerns that the sidewall will overheat.

[0015] (2) Carcass Therefore, in the present invention, the carcass is formed by winding around the bead 5 with a two-layer structure consisting of a first carcass ply 7A and a second carcass ply 7B, each equipped with a carcass cord, as shown in Figure 1. Furthermore, when the outer diameter of the tire is Dt (mm), the winding height of the first carcass ply 7A located on the outside is P1 (mm), and the winding height of the second carcass ply 7B located on the inside is P2 (mm), the ratio ((P1-P2) / Dt) is controlled to be less than 0.07.

[0016] In other words, by reducing (P1-P2), the rigidity of the sidewall can be increased, preventing the concentration of strain in the sidewall. Furthermore, by making the ratio of (P1-P2) to the outer diameter of the tire ((P1-P2) / Dt)) sufficiently small, less than 0.07, the entire tire can flex sufficiently, which is thought to suppress heat generation in the sidewall and further improve fuel efficiency.

[0017] (3) Rubber composition that makes up the tread (rubber composition for tread) In this invention, when forming the tread, a rubber composition (tread rubber composition) is used that contains more than 75 parts by mass of silica per 100 parts by mass of rubber component and more than 15% by mass of acetone extract.

[0018] (a) Silica formulation By including a high amount of silica, more than 75 parts by mass per 100 parts by mass of rubber component, the loss tangent (30°C tanδ) measured in tensile deformation mode under conditions of 30°C, 10Hz frequency, 5% initial strain, and 1% dynamic strain can be reduced. This is thought to suppress heat generation in the tire during operation and further improve fuel efficiency.

[0019] In other words, the loss tangent tanδ is a viscoelastic parameter that indicates the energy absorption performance. The larger the value, the more energy is absorbed and converted into heat, resulting in greater heat generation. Therefore, by controlling the 30°C tanδ to be small, it is possible to suppress tire heat generation during operation, thereby further improving fuel efficiency.

[0020] The loss tangent (tanδ) can be measured using a viscoelasticity measuring device such as the "Iplexer®" manufactured by GABO.

[0021] (b) Acetone extract (AE amount) The amount of air-entraining (AE) can be considered an indicator of the amount of material that imparts plasticity to rubber components, such as softeners (plasticizers), in a rubber composition, and can also be considered an indicator of the softness of the rubber composition.

[0022] In this invention, since the amount of AE is significantly controlled to more than 15% by mass, the softness of the tread is maintained, making it easier to obtain the effect of flexing throughout the tire, and thus it is thought that fuel efficiency can be further improved.

[0023] The amount of AE can be measured in accordance with JIS K 6229:2015. Specifically, the amount of AE (mass%) can be obtained by immersing a vulcanized rubber test piece cut from the measurement site in acetone for a predetermined time and determining the mass loss rate (%) of the test piece.

[0024] More specifically, the soluble components can be extracted by immersing each vulcanized rubber test piece in acetone for 72 hours at room temperature and atmospheric pressure, measuring the mass of each test piece before and after extraction, and then determining the result using the following formula. AE amount (mass%) = {(mass of rubber test piece before extraction - mass of rubber test piece after extraction)} / (mass of rubber test piece before extraction)} × 100

[0025] (4) Diameter of band cord, belt cord, carcass cord In this invention, the sum of the diameters D1 (mm) of the band cord, D2 (mm) of the belt cord, and D3 (mm) of the carcass cord (D1 + D2 + D3) is further controlled to be less than 2.00 (Equation 2).

[0026] By using thinner cords, the weight of the bands, belts, and carcass can be reduced, which is expected to lead to further weight reduction of the tire and further improvement in fuel efficiency.

[0027] Furthermore, in the above, the "diameter of the band cord" and the "diameter of the carcass cord" can be measured in accordance with the method specified in JIS L1017:2002 "Test method for chemical fiber tire cords," and the "diameter of the belt cord" can be measured in accordance with the test method specified in JIS G3510:1992 "Test method for steel tire cords." The "diameter of the cord" refers to the diameter when the circumscribed circle of the cross-section perpendicular to the direction of cord extension is a perfect circle, and in the case of an ellipse, it refers to the equivalent diameter of a circle (the diameter of a circle assuming the same cross-sectional area as a perfect circle).

[0028] [2] More preferred embodiment of the tire according to the present invention The tire according to the present invention can achieve even greater effects by adopting the following embodiments.

[0029] 1. PET band In the present invention, the PET fibers used in the PET band are preferably sustainable materials that are suitable for environmental protection. Examples of sustainable PET fibers (sustainable PET fibers) include recycled PET fibers (recycled PET fibers) made from recycled plastic waste such as used PET bottles, old items, and waste materials, and PET fibers (bio-PET fibers) made from biomass.

[0030] Furthermore, the specific diameter D1 of the PET band (band cord) is preferably 0.60 mm or less, and more preferably 0.55 mm or less. The lower limit is preferably 0.45 mm or more, and more preferably 0.50 mm or more.

[0031] The PET band can be made from either a single-ply band (made by twisting one yarn) or a double-ply band (made by twisting two yarns). The filaments that make up the yarn can be PET fibers only, or a mixture of PET fibers and other fibers (such as polyamide fibers).

[0032] Furthermore, the number of cords per 50 mm width of the PET band (band cord) (ends: cords / 5 cm) is preferably more than 30 cords / 5 cm, more preferably more than 40 cords / 5 cm, and even more preferably more than 45 cords / 5 cm. There is no particular upper limit, but it is preferably less than 70 cords / 5 cm, more preferably less than 60 cords / 5 cm, and even more preferably less than 55 cords / 5 cm.

[0033] The end length of the band cord described above can be measured in accordance with the method specified in JIS L1017:2002 "Test Method for Chemical Fiber Tire Cords".

[0034] PET bands can be manufactured by treating PET cords with an adhesive and then bonding them to a predetermined rubber composition for bands. As adhesives used to bond PET cords, for example, epoxy compounds such as EX-313 (glycerin polyglycidyl ether, manufactured by Nagase ChemteX Corporation) and RFL (resorcinol-formaldehyde latex) can be used.

[0035] Furthermore, the band may consist of one or two layers. The band may also be formed across the entire width of the tread, or only at the ends of the tread.

[0036] 2. Tread (1) Silica content In the present invention, the silica content in the tread rubber composition is set to be more than 75 parts by mass per 100 parts by mass of rubber component, as described above, but it is more preferably more than 80 parts by mass, even more preferably more than 90 parts by mass, and even more preferably more than 100 parts by mass. In this way, by further enriching the silica content, the 30°C tanδ mentioned above can be further reduced, and thus it is thought that fuel efficiency can be further improved. As an upper limit, for example, it is preferably less than 140 parts by mass, more preferably less than 130 parts by mass, even more preferably less than 120 parts by mass, and even more preferably less than 110 parts by mass.

[0037] Furthermore, when incorporating silica, if the particle size (average primary particle size) is too small, the processability will be poor, so it is preferable to use silica with a particle size greater than 8 nm. It is more preferable if it is 15 nm or larger. On the other hand, from the viewpoint of ensuring the reinforcing properties of the rubber, it is preferable if it is 25 nm or smaller, and more preferable if it is 22 nm or smaller.

[0038] The average primary particle diameter of silica refers to the average value of measurements taken by observing the smallest particle unit of silica constituting the aggregated structure as a circle, and measuring the absolute maximum length of that smallest particle as the diameter of the circle. This can be determined by observing with a transmission or scanning electron microscope, measuring 400 or more primary silica particles observed within the field of view, and averaging the results.

[0039] Specifically, silica extracted from the rubber composition cut from a tire can be directly observed using an electron microscope or similar device. The average primary particle diameter can then be calculated by determining the average of the equal cross-sectional area diameters from the area of ​​each silica particle obtained and then calculating the average value.

[0040] The raw materials for silica are not particularly limited. For example, they may be mineral-derived raw materials such as quartz, or biologically derived raw materials such as rice husks (e.g., silica made from biomass materials such as rice husks), or silica recycled from silica-containing products may be used. Among these, hydrated silica prepared by a wet process is preferred because it contains a large amount of silanol groups. However, from an environmental protection standpoint, sustainable silica (silica made from biomass materials or silica recycled from silica-containing products) is preferred.

[0041] Silica derived from biomass materials (biomass silica) can be obtained, for example, by extracting silicates from rice husk ash obtained by burning rice husks using a sodium hydroxide solution, and then using these silicates to react with sulfuric acid in the same way as conventional wet silica, the precipitate of silicon dioxide is filtered, washed with water, dried, and pulverized.

[0042] Recycled silica (silica recycled from silica-containing products) can be obtained from silica-containing products such as semiconductors and other electronic components, tires, desiccants, and diatomaceous earth and other filter materials. The recovery method is not particularly limited and can include thermal decomposition and decomposition by electromagnetic waves. Among these, silica recovered from semiconductors and other electronic components or tires is preferred.

[0043] When silica crystallizes, it becomes insoluble in water, and its component, silicic acid, cannot be utilized. By controlling the combustion temperature and combustion time, the crystallization of silica in rice husk ash can be suppressed (see Japanese Patent Publication No. 2009-2594, Akita Prefectural University Web Journal B / 2019, vol.6, pp.216-222, etc.).

[0044] Amorphous silica extracted from rice husks can be commercially available from companies such as Wilmar.

[0045] These silicas may be used individually or in combination of two or more. Furthermore, using sustainable silica such as biomass silica or recycled silica is preferable from an environmental protection (sustainability) standpoint.

[0046] (2) AE amount In the present invention, the amount of AE in the tread rubber composition is set to more than 15% by mass, as described above, but it is more preferably more than 16% by mass, even more preferably more than 17% by mass, and even more preferably more than 18% by mass. By further increasing the amount of AE in this way, the tread rubber can be made even softer, and the effect of the entire tire flexing can be obtained more sufficiently, so it is thought that fuel efficiency can be further improved. As an upper limit, for example, it is preferably less than 22% by mass, more preferably less than 21% by mass, even more preferably less than 20% by mass, and even more preferably less than 19% by mass.

[0047] (3) Content of isoprene rubber In the present invention, it is preferable that the tread rubber composition contains more than 25 parts by mass of isoprene-based rubber per 100 parts by mass of rubber component.

[0048] By including more than 25 parts by mass of isoprene-based rubber in 100 parts by mass of rubber component, it is possible to create a low-heat-generating tread that can reduce heat generation during driving, thereby further improving fuel efficiency. It is more preferable to include 30 parts by mass or more, and even more preferable to include 40 parts by mass or more. As an upper limit, for example, it is preferable to include 70 parts by mass or less, and more preferable to include 60 parts by mass or less.

[0049] Specific examples of isoprene-based rubbers include natural rubber (NR), modified natural rubber (modified NR), modified natural rubber (modified NR), and synthetic polyisoprene (isoprene rubber (IR), modified isoprene rubber (modified IR)). Among these, NR is preferred due to its superior strength. For NR, common types used in the tire industry, such as SVR-L, SIR20, RSS#3, and TSR20, can be used.

[0050] (4) 30℃ tanδ As mentioned above, fuel efficiency can be further improved by controlling the 30°C tanδ to a small value. Specifically, the 30°C tanδ is preferably less than 0.20, and more preferably less than 0.19. As a lower limit, for example, it is preferably greater than 0.15, and more preferably greater than 0.16.

[0051] (5) Tread thickness In the present invention, the tread thickness is preferably greater than 6 mm, which is thought to reduce the compression the band receives and improve high-speed durability. It is more preferably 8 mm or more, and even more preferably 10 mm or more. As an upper limit, for example, it is preferably 20 mm or less, more preferably 15 mm or less, and even more preferably 12 mm or less.

[0052] Furthermore, "tread thickness" refers to the thickness of the tread on the tire's equatorial plane in the tire's radial cross-section. When the tread is formed from a single rubber composition, it refers to the thickness of that rubber composition. When it is formed from a laminated structure of multiple rubber compositions, as described later, it refers to the thickness of the cap rubber layer, which is the outermost layer on the contact surface side. This can be measured by cutting the tire radially and aligning the bead portion with the normal rim width.

[0053] Furthermore, "standard rim" refers to the rim specified for each tire within the standard system that includes the standard on which the tire is based. For example, for JATMA (Japan Automobile Tire Manufacturers Association), it refers to the standard rim for the applicable size listed in the "JATMA YEAR BOOK," for ETRTO (The European Tyre and Rim Technical Organisation), 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." Refer to JATMA, ETRTO, and TRA in that order, and if an applicable size is available at the time of reference, follow that standard. In the case of tires not specified in the standard, it refers to the rim with the smallest diameter and the narrowest rim width among rims that can be mounted on and can maintain internal pressure, i.e., rims that do not cause air leakage from between the rim and tire.

[0054] (6) Multi-layered tread In the present invention, the tread may consist of only one layer, which is the contact surface layer (cap rubber layer), or it may consist of two layers, with a base rubber layer provided inside the cap rubber layer, or it may consist of three layers, or four or more layers. In this case, the rubber composition for the tread described above is the rubber composition that forms the cap rubber layer, which is the outermost layer on the contact surface side, and it is preferable that it satisfies each of the above parameters.

[0055] In this case, the thickness of the cap rubber layer over the entire tread is preferably 10% or more, more preferably 30% or more, even more preferably 50% or more, and even more preferably 70% or more.

[0056] 3. Belt In this invention, it is preferable that the belt cord constituting the belt is composed of four or fewer filaments. By reducing the number of filaments in this way, even if the filaments are made of metal, the weight can be reduced, further reducing the weight of the tire, and thus it is believed that fuel efficiency can be further improved.

[0057] The material of the filaments constituting the belt cord is not particularly limited, but it is preferably made of metal, more preferably iron, and especially preferably steel. The structure of the belt cord is preferably one of the following: an untwisted 1x1 structure, a single-twist 1x2 structure, a 1x3 structure, a 1x4 structure, or a layered 2+2 structure. The cross-sectional shape of the filaments is preferably circular, but they may also be elliptical, and they may also be corrugated or plated.

[0058] Furthermore, the specific diameter D2 of the belt cord is preferably 0.65 mm or less, and more preferably 0.55 mm or less. The lower limit is preferably 0.45 mm or more, and more preferably 0.50 mm or more.

[0059] Furthermore, the number of cords per 50 mm of belt cord width (ends: cords / 5 cm) is preferably 20 cords / 5 cm or more, more preferably 25 cords / 5 cm or more, and even more preferably 30 cords / 5 cm or more. As an upper limit, for example, it is preferably 60 cords / 5 cm or less, more preferably 55 cords / 5 cm or less, and even more preferably 50 cords / 5 cm or less.

[0060] The end length of the belt cord described above can be measured in accordance with the method specified in JIS L1017:2002 "Test Method for Chemical Fiber Tire Cords".

[0061] 4. Carcass In the present invention, as described above, the carcass is constructed by winding together a two-layer structure of a first carcass ply and a second carcass ply, and ((P1-P2) / Dt) is set to less than 0.07, but ((P1-P2) / Dt) is more preferably less than 0.067, even more preferably less than 0.065, and even more preferably less than 0.063. As a lower limit, for example, it is preferably greater than 0.056, more preferably greater than 0.058, and even more preferably greater than 0.060. This is thought to further increase the rigidity of the sidewall portion, more effectively prevent the concentration of strain in the sidewall portion, and allow the entire tire to flex more sufficiently, thereby further suppressing heat generation in the sidewall portion and further improving fuel efficiency.

[0062] The carcass cord can be made of fibers, and conventionally known fibers such as polyester fibers including PET (polyethylene terephthalate) fibers and PEN (polyethylene naphthalate) fibers, polyamide fibers such as nylon 6 fibers and nylon 66 fibers, and aramid fibers can be used as the fibers that make up the carcass cord. Single-ply cords made by twisting one yarn or double-ply cords made by twisting two yarns are preferred. The fibers that make up the carcass cord may be recycled from used or waste materials (recycled materials) or synthesized from biomass (biomass materials).

[0063] Furthermore, the specific diameter D3 of the carcass cord is preferably 0.70 mm or less, and more preferably 0.65 mm or less. The lower limit is preferably 0.55 mm or more, and more preferably 0.60 mm or more.

[0064] Furthermore, the carcass cord can be constructed using either a single-ply twisted yarn or a double-ply twisted yarn.

[0065] Furthermore, the number of cords per 50 mm of carcass width (ends: cords / 5 cm) is preferably 40 cords / 5 cm or more, and more preferably 45 cords / 5 cm or more. As an upper limit, for example, it is preferably 60 cords / 5 cm or less, and more preferably 55 cords / 5 cm or less.

[0066] The end length of the carcass cord described above can be measured in accordance with the method specified in JIS L1017:2002 "Test Method for Chemical Fiber Tire Cords".

[0067] 5. D1 + D2 + D3 In the present invention, (D1+D2+D3) is set to less than 2.00 as described above, but it is more preferably less than 1.80, and even more preferably less than 1.70. This allows for further weight reduction of the tire, which is thought to further improve fuel efficiency. As a lower limit, for example, it is preferably greater than 1.55, more preferably greater than 1.60, and even more preferably greater than 1.65.

[0068] [3] Embodiment The present invention will be described in detail below based on embodiments.

[0069] 1. Tire according to this embodiment Figure 2 is a schematic cross-sectional view illustrating the tire according to this embodiment. In Figure 2, the vertical direction is the radial direction of the tire, the horizontal direction is the axis of rotation of the tire, and the direction perpendicular to the plane of the paper is the circumferential direction of the tire. In Figure 2, the dashed line CL represents the equatorial plane of the tire. Note that, except for the tread pattern, the shape of this tire is symmetrical with respect to the equatorial plane, so Figure 2 shows 1 / 4 of the entire tire.

[0070] As shown in Figure 2, the tire 1 comprises a tread 2, a pair of sidewalls 3, a pair of chafers 4, a pair of beads 5, an inner liner 6, a carcass 7, a belt 8, a pair of fillers 9, and a band 10, with the carcass 7, belt 8, band 10, and tread 2 arranged from the inside to the outside in the radial direction of the tire.

[0071] By adopting this configuration, using PET bands as band cords, appropriately forming the carcass, forming the tread using an appropriately formulated tread rubber composition, and further appropriately controlling each of the above-mentioned parameters, it is believed that fuel efficiency can be further improved as described above.

[0072] 2. Rubber composition for treads In this embodiment, the tread rubber composition can be obtained by kneading various compounding materials such as rubber components, reinforcing materials, antioxidants, oils, resin materials, and antioxidants.

[0073] (1) Compounding materials (a) Rubber component The rubber component in the tread rubber composition is not particularly limited, and for example, diene rubbers such as natural rubber (NR), styrene-butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), and butyl rubber (IIR) can be used. These may be used individually or in combination of two or more, and in the present invention, a combination of NR, SBR, and BR is preferred.

[0074] (i) SBR In the present invention, the weight-average molecular weight of SBR is preferably, for example, more than 100,000 and less than 2,000,000. The vinyl content (amount of 1,2-bonded butadiene units) of SBR is preferably, for example, more than 5% by mass, more preferably more than 10% by mass, and even more preferably more than 15% by mass. On the other hand, it is preferably less than 70% by mass, more preferably less than 40% by mass, and even more preferably less than 30% by mass. The structural identification of SBR (measurement of styrene content and vinyl content) can be performed, for example, using an instrument from the JNM-ECA series manufactured by JEOL Ltd.

[0075] The SBR is not particularly limited, and for example, emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), etc., can be used. The SBR may be either unmodified SBR or modified SBR. Furthermore, hydrogenated SBR, in which the butadiene portion of the SBR is hydrogenated, may be used. Hydrogenated SBR may be obtained by subsequently hydrogenating the BR portion of the SBR, or a similar structure may be obtained by copolymerizing styrene, ethylene, and butadiene.

[0076] The modified SBR is preferably an SBR having a functional group that interacts with a filler such as silica. Examples include a terminally modified SBR (terminally modified SBR having the functional group at the terminal) in which at least one end of the SBR is modified with a compound having the functional group (modifying agent), a main chain modified SBR having the functional group in the main chain, a main chain terminally modified SBR having the functional group in both the main chain and the terminal (for example, a main chain terminally modified SBR having the functional group in the main chain and at least one end modified with the modifying agent), and a terminally modified SBR that is modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule, and in which hydroxyl groups or epoxy groups are introduced.

[0077] Examples of the functional group include an amino group, an amide group, a silyl group, an alkoxysilyl group, an isocyanate group, an imino group, an imidazole group, a urea group, an ether group, a carbonyl group, an oxycarbonyl group, a mercapto group, a sulfide group, a disulfide group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, an ammonium group, an imide group, a hydrazo group, an azo group, a diazo group, a carboxyl group, a nitrile group, a pyridyl group, an alkoxy group, a hydroxyl group, an oxy group, an epoxy group, etc. These functional groups may have substituents.

[0078] As the modified SBR, for example, SBR modified with a compound (modifying agent) represented by the following formula can be used.

[0079]

Chemical formula

[0080] In the formula, R 1 , R 2 and R 3 are the same or different and represent an alkyl group, an alkoxy group, a silyloxy group, an acetal group, a carboxyl group (-COOH), a mercapto group (-SH), or derivatives thereof. R 4 and R 5 are the same or different and represent a hydrogen atom or an alkyl group. R 4 and R 5 may combine to form a ring structure together with a nitrogen atom. n represents an integer.

[0081] As the modified SBR modified with the compound (modifying agent) represented by the above formula, SBR in which the polymerization terminal (active terminal) of solution-polymerized styrene-butadiene rubber (S-SBR) is modified with the compound represented by the above formula (modified SBR described in JP-A-2010-111753, etc.) can be used.

[0082] R 1 , R 2 and R 3A suitable alkoxy group is used (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably an alkoxy group having 1 to 4 carbon atoms). 4 and R 5 A suitable alkyl group (preferably an alkyl group having 1 to 3 carbon atoms) is used. n is preferably 1 to 5, more preferably 2 to 4, and even more preferably 3. Also, R 4 and R 5 When the alkoxy group is bonded to form a ring structure with the nitrogen atom, it is preferably a 4- to 8-membered ring. Note that the alkoxy group also includes cycloalkoxy groups (such as cyclohexyloxy group) and aryloxy groups (such as phenoxy group and benzyloxy group).

[0083] Specific examples of the above-mentioned denaturing agents include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, and 3-diethylaminopropyltriethoxysilane. These may be used individually or in combination of two or more.

[0084] Furthermore, modified SBR can also be modified using the following compounds (modifying agents): For example, polyglycidyl ethers of polyhydric alcohols such as ethylene glycol diglycidyl ether, glycerin triglycidyl ether, trimethylolethane triglycidyl ether, and trimethylolpropane triglycidyl ether; polyglycidyl ethers of aromatic compounds having two or more phenol groups such as diglycidyl bisphenol A; polyepoxy compounds such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxylated liquid polybutadiene; epoxy group-containing tertiary amines such as 4,4'-diglycidyl-diphenylmethylamine and 4,4'-diglycidyl-dibenzylmethylamine; diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline, Diglycidylamino compounds such as diglycidyl orthotoluidine, tetraglycidylmetoxylendiamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, and tetraglycidyl-1,3-bisaminomethylcyclohexane; amino group-containing acid chlorides such as bis-(1-methylpropyl)carbamate chloride, 4-morpholine carbonyl chloride, 1-pyrrolidinecarbonyl chloride, N,N-dimethylcarbamate chloride, and N,N-diethylcarbamate chloride; epoxy group-containing silane compounds such as 1,3-bis-(glycidyloxypropyl)-tetramethyldisiloxane and (3-glycidyloxypropyl)-pentamethyldisiloxane;(Trimethylsilyl)[3-(trimethoxysilyl)propyl]sulfide, (Trimethylsilyl)[3-(triethoxysilyl)propyl]sulfide, (Trimethylsilyl)[3-(tributoxysilyl)propyl]sulfide, (Trimethylsilyl)[3-(methyldimethoxysilyl)propyl]sulfide, (Trimethylsilyl)[3-(methyldiethoxysilyl)propyl]sulfide, (Trimethylsilyl)[3-(methyldipropoxysilyl)propyl]sulfide Sulfide group-containing silane compounds such as [sisilyl)propyl]sulfide and (trimethylsilyl)[3-(methyldibutoxysilyl)propyl]sulfide; N-substituted aziridine compounds such as ethyleneimine and propyleneimine; methyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, N,N-bis(trimethylsilyl)aminoethyl Alkoxysilanes such as tiltriethoxysilane; (thio)benzophenone compounds having an amino group and / or a substituted amino group, such as 4-N,N-dimethylaminobenzophenone, 4-N,N-di-t-butylaminobenzophenone, 4-N,N-diphenylaminobenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(diphenylamino)benzophenone, and N,N,N',N'-bis-(tetraethylamino)benzophenone; 4-N,N- Benzaldehyde compounds having an amino group and / or a substituted amino group, such as dimethylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde, and 4-N,N-divinylaminobenzaldehyde; N-substituted pyrrolidones such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, Nt-butyl-2-pyrrolidone, and N-methyl-5-methyl-2-pyrrolidone; N-substituted piperidones such as N-methyl-2-piperidone, N-vinyl-2-piperidone, and N-phenyl-2-piperidone;N-substituted lactams such as N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-laurylolactam, N-vinyl-ω-laurylolactam, N-methyl-β-propiolactam, and N-phenyl-β-propiolactam; as well as N,N-bis-(2,3-epoxypropoxy)-aniline, 4,4-methylene-bis-(N,N-glycidylaniline), and tris-(2,3-epoxypropyl)-1,3,5-triazine-2,4,6-triones. Examples include N,N-diethylacetamide, N-methylmaleimide, N,N-diethylurea, 1,3-dimethylethyleneurea, 1,3-divinylethyleneurea, 1,3-diethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 4-N,N-dimethylaminoacetophene, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-propanone, and 1,7-bis(methylethylamino)-4-heptanone. Modification using the above compounds (modifiers) can be carried out by known methods.

[0085] For example, SBR manufactured and sold by companies such as Sumitomo Chemical Co., Ltd., ENEOS Material Co., Ltd., Asahi Kasei Corporation, and Nippon Zeon Co., Ltd. can be used. SBR may be used alone or in combination of two or more types.

[0086] The SBR content in 100 parts by mass of rubber component is preferably 55 parts by mass or more, and more preferably 60 parts by mass or more. As an upper limit, for example, it is preferably 85 parts by mass or less, and more preferably 80 parts by mass or less.

[0087] (b) Isoprene rubber Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. However, as mentioned above, NR is preferred due to its superior strength.

[0088] As mentioned above, for NR, common types used in the tire industry can be used, such as SVR-L, SIR20, RSS#3, TSR20, etc. For IR, there are no particular limitations, and common types used in the tire industry can be used, such as IR2200 manufactured by Nippon Zeon Co., Ltd. Examples of modified NR include deproteinized natural rubber (DPNR) and high-purity natural rubber (UPNR), examples of modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber, and examples of modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used individually or in combination of two or more types.

[0089] The preferred content of isoprene-based rubber in 100 parts by mass of rubber component is as described above.

[0090] (H)BR The weight-average molecular weight of BR is, for example, greater than 100,000 and less than 2,000,000. The vinyl content of BR is, for example, greater than 1% by mass and less than 30% by mass. The cis content of BR is, for example, greater than 1% by mass and 98% by mass or less. The trans content of BR is, for example, greater than 1% by mass and less than 60% by mass. The cis content can be measured by infrared absorption spectroscopy.

[0091] The BR is not particularly limited, and can be high-cis content BR (cis content of 90% or more), low-cis content BR, or BR containing syndiotactic polybutadiene crystals. The BR can be either unmodified or modified, and as for modified BR, for example, BR modified with a compound (modifying agent) represented by the following formula can be used.

[0092] [ka]

[0093] Note that in the formula, R 1 , R 2 and R 3R represents, either identical or distinct, an alkyl group, an alkoxy group, a silyloxy group, an acetal group, a carboxyl group (-COOH), a mercapto group (-SH), or a derivative thereof. 4 and R 5 R represents a hydrogen atom or an alkyl group, either identical or different. 4 and R 5 These atoms may bond to form a ring structure with the nitrogen atom. n represents an integer.

[0094] Modified BR, which has been modified by the compound (modifying agent) represented by the above formula, is an example of BR in which the polymerization end (active end) has been modified by the compound represented by the above formula.

[0095] R 1 , R 2 and R 3 A suitable alkoxy group is used (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably an alkoxy group having 1 to 4 carbon atoms). 4 and R 5 A suitable alkyl group (preferably an alkyl group having 1 to 3 carbon atoms) is used. n is preferably 1 to 5, more preferably 2 to 4, and even more preferably 3. Also, R 4 and R 5 When the alkoxy group is bonded to form a ring structure with the nitrogen atom, it is preferably a 4- to 8-membered ring. Note that the alkoxy group also includes cycloalkoxy groups (such as cyclohexyloxy group) and aryloxy groups (such as phenoxy group and benzyloxy group).

[0096] Specific examples of the above-mentioned denaturing agents include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, and 3-diethylaminopropyltriethoxysilane. These may be used individually or in combination of two or more.

[0097] Furthermore, modified BR can also be modified using the following compounds (modifying agents): For example, polyglycidyl ethers of polyhydric alcohols such as ethylene glycol diglycidyl ether, glycerin triglycidyl ether, trimethylolethane triglycidyl ether, and trimethylolpropane triglycidyl ether; polyglycidyl ethers of aromatic compounds having two or more phenol groups such as diglycidyl bisphenol A; polyepoxy compounds such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxy-modified liquid polybutadiene; epoxy-group-containing tertiary amines such as 4,4'-diglycidyl-diphenylmethylamine and 4,4'-diglycidyl-dibenzylmethylamine; diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline, Diglycidylamino compounds such as diglycidyl orthotoluidine, tetraglycidylmetoxylendiamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, and tetraglycidyl-1,3-bisaminomethylcyclohexane; amino group-containing acid chlorides such as bis-(1-methylpropyl)carbamate chloride, 4-morpholine carbonyl chloride, 1-pyrrolidinecarbonyl chloride, N,N-dimethylcarbamate chloride, and N,N-diethylcarbamate chloride; epoxy group-containing silane compounds such as 1,3-bis-(glycidyloxypropyl)-tetramethyldisiloxane and (3-glycidyloxypropyl)-pentamethyldisiloxane;(Trimethylsilyl)[3-(trimethoxysilyl)propyl]sulfide, (Trimethylsilyl)[3-(triethoxysilyl)propyl]sulfide, (Trimethylsilyl)[3-(tributoxysilyl)propyl]sulfide, (Trimethylsilyl)[3-(methyldimethoxysilyl)propyl]sulfide, (Trimethylsilyl)[3-(methyldiethoxysilyl)propyl]sulfide, (Trimethylsilyl)[3-(methyldipropoxysilyl)propyl]sulfide Sulfide group-containing silane compounds such as [sisilyl)propyl]sulfide and (trimethylsilyl)[3-(methyldibutoxysilyl)propyl]sulfide; N-substituted aziridine compounds such as ethyleneimine and propyleneimine; methyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, N,N-bis(trimethylsilyl)aminoethyl Alkoxysilanes such as tiltriethoxysilane; (thio)benzophenone compounds having an amino group and / or a substituted amino group, such as 4-N,N-dimethylaminobenzophenone, 4-N,N-di-t-butylaminobenzophenone, 4-N,N-diphenylaminobenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(diphenylamino)benzophenone, and N,N,N',N'-bis-(tetraethylamino)benzophenone; 4-N,N- Benzaldehyde compounds having an amino group and / or a substituted amino group, such as dimethylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde, and 4-N,N-divinylaminobenzaldehyde; N-substituted pyrrolidones such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, Nt-butyl-2-pyrrolidone, and N-methyl-5-methyl-2-pyrrolidone; N-substituted piperidones such as N-methyl-2-piperidone, N-vinyl-2-piperidone, and N-phenyl-2-piperidone;N-substituted lactams such as N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-laurylolactam, N-vinyl-ω-laurylolactam, N-methyl-β-propiolactam, and N-phenyl-β-propiolactam; as well as N,N-bis-(2,3-epoxypropoxy)-aniline, 4,4-methylene-bis-(N,N-glycidylaniline), and tris-(2,3-epoxypropyl)-1,3,5-triazine-2,4,6-triones. Examples include N,N-diethylacetamide, N-methylmaleimide, N,N-diethylurea, 1,3-dimethylethyleneurea, 1,3-divinylethyleneurea, 1,3-diethyl-2-imidazolidinone, 1-methyl-3-ethyl-2-imidazolidinone, 4-N,N-dimethylaminoacetophene, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-propanone, and 1,7-bis(methylethylamino)-4-heptanone. Modification using the above compounds (modifying agents) can be carried out by known methods. These modified BRs may be used individually or in combination of two or more.

[0098] For example, BR products from companies such as Ube Industries, Ltd., ENEOS Material Corporation, Asahi Kasei Corporation, and Nippon Zeon Corporation can be used.

[0099] The BR content in 100 parts by mass of rubber component is preferably 8 parts by mass or more, and more preferably 10 parts by mass or more. On the other hand, it is preferably 15 parts by mass or less, and more preferably 12 parts by mass or less.

[0100] (ii) Other rubber components The tread rubber composition may also include, if necessary, other rubber components such as nitrile rubber (NBR) or other rubbers (polymers) commonly used in tire manufacturing.

[0101] Furthermore, the raw materials (monomers) for synthetic rubbers such as SBR and BR mentioned above may be derived from underground resources such as petroleum and natural gas, or they may be recycled from rubber products such as tires or non-rubber products such as polystyrene.

[0102] The monomers obtained by recycling (recycled monomers) are not particularly limited and include recycled isoprene, recycled butadiene, and recycled aromatic vinyl. Examples of butadiene include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyl include styrene. In particular, recycled isoprene, butadiene, and / or recycled styrene are preferred as raw materials.

[0103] The method for producing recycled monomer is not particularly limited, and for example, it can be synthesized from recycled naphtha obtained by decomposing rubber products such as tires. Furthermore, the method for producing recycled naphtha is not particularly limited, and for example, rubber products such as tires may be decomposed under high temperature and pressure, decomposed by microwaves, or extracted after mechanical grinding.

[0104] Furthermore, the raw materials (monomers) for synthetic rubbers such as IR, SBR, and BR may be derived from biomass. Here, biomass refers to substances derived from natural resources such as plants. Biomass is not particularly limited, but examples include agricultural, forestry, and fishery products, sugars, wood, plant residues after obtaining useful components, plant-derived ethanol, and biomass naphtha. Biomass-derived monomers (biomass monomers) are not particularly limited, but examples include biomass-derived butadiene and biomass-derived aromatic vinyl. Examples of butadiene include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyl are not particularly limited, but examples include styrene. In addition, the method for producing biomass monomers is not particularly limited, and examples include biological and / or chemical and / or physical conversion of plants and animals. Typical biological conversions include fermentation by microorganisms, while chemical and / or physical conversions include those by catalysts, high heat, high pressure, electromagnetic waves, critical liquids, and combinations thereof.

[0105] The polymer synthesized from biomass monomer components (biomass polymer) is not particularly limited, and examples include polybutadiene rubber synthesized from biomass-derived butadiene, and aromatic vinyl / butadiene copolymers synthesized from biomass-derived butadiene and / or biomass-derived aromatic vinyl. Examples of the aromatic vinyl / butadiene copolymer include styrene-butadiene rubber synthesized from biomass-derived butadiene and / or biomass-derived styrene.

[0106] Whether the raw materials for a polymer are biomass-derived can be determined by measuring pMC (percent Modern Carbon) in accordance with ASTMD6866-10.

[0107] pMC stands for Modern Standard Reference Carbon. 14 Sample relative to C concentration 14This is the ratio of C concentrations, and this value is used as an indicator of the biomass ratio of the compound (rubber). The significance of this value is described below.

[0108] 1 mole of carbon atoms (6.02 × 10⁻¹⁰) 23 (Each) contains approximately 6.02 × 10¹⁶ atoms, which is about one trillionth of the amount of carbon atoms in a normal atom. 11 individual 14 C exists. 14 Carbon dioxide is called a radioactive isotope, and its half-life is 5730 years, decreasing regularly. It takes 226,000 years for all of them to decay. Therefore, in fossil fuels such as coal, oil, and natural gas, which are thought to have been fixed for more than 226,000 years after atmospheric carbon dioxide was taken in by plants, etc., it was initially contained within these materials. 14 All elements of C have decayed. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas are no longer viable. 14 It contains absolutely no element C. Therefore, chemical substances produced using these fossil fuels as raw materials also contain C. 14 It contains absolutely no element C.

[0109] on the other hand, 14 C is continuously produced in the Earth's atmospheric environment through nuclear reactions caused by cosmic rays, and its decrease due to radioactive decay balances this process. 14 The amount of C is constant. Therefore, the amount of biomass resource-derived substances currently circulating in the environment 14 As mentioned above, the carbon concentration is approximately 1 × 10¹⁶ of the total carbon atoms. -12 The values ​​are approximately in the range of 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 given compound (rubber).

[0110] this 14 C is typically measured as follows: Using accelerator mass spectrometry based on a tandem accelerator, 13 C concentration ( 13 C / 12 C), 14 C concentration ( 14 C / 12 Perform measurement C). In the measurement, 14 As a modern standard reference for the concentration of C, the amount of cyclic carbon in nature as of 1950 14 The C concentration will be used. The specific standard material will be the oxalic acid standard provided by NIST (National Institute of Standards and Technology). The specific radioactivity of carbon in this oxalic acid (per gram of carbon) will be used. 14 The radioactivity intensity of C is separated by carbon isotope, 13 The standard value is obtained by correcting C to a constant value and applying decay correction from 1950 AD to the measurement date. 14 This value is used as the C concentration value (100%). The ratio of this value to the value of the sample actually measured is the pMC value.

[0111] Therefore, if rubber is made from 100% biomass (natural) materials, although there are regional differences, under normal conditions it will often not reach 100, and will show a value of approximately 110 pMC. On the other hand, regarding chemical substances derived from fossil fuels such as petroleum, 14 When the C concentration is measured, it will show a value of approximately 0 pMC (for example, 0.3 pMC). This value corresponds to a biomass ratio of 0% as mentioned above.

[0112] From the above, it is preferable from an environmental protection (sustainability) standpoint to use materials such as rubber with a high pMC value, that is, materials such as rubber with a high biomass ratio, in rubber compositions.

[0113] (b) Compounding materials other than rubber components (i) Filler As described above, the tread rubber composition contains silica as a reinforcing agent, but may also contain other fillers as needed, such as carbon black, calcium carbonate, talc, alumina, clay, aluminum hydroxide, mica, etc. When silica is used, it is preferable to use it in combination with a silane coupling agent.

[0114] Regarding the amount of fillers to be added, first, as mentioned above, silica should be added in an amount of more than 75 parts by mass per 100 parts by mass of rubber component. However, the total amount of other fillers added is preferably 85 parts by mass or more, and more preferably 100 parts by mass or more, per 100 parts by mass of rubber component. On the other hand, from the viewpoint of dispersibility in the rubber composition, it is preferably 130 parts by mass or less, and more preferably 115 parts by mass or less.

[0115] (i) Silica In the tread rubber composition, the silica content per 100 parts by mass of rubber component is as described above.

[0116] The BET specific surface area of ​​silica is considered to be 100 m² from the perspective of obtaining good durability performance. 2 It is preferable that the amount is greater than / g, and 130m 2 It is more preferable if it is greater than / g. On the other hand, 250m 2 It is preferable that the amount be less than / g, and 200m 2 It is more preferable if the value is less than / g. The BET specific surface area mentioned above is the N2SA value measured by the BET method in accordance with ASTM D3037-93.

[0117] The silica used is not particularly limited; for example, silica prepared by the dry method (anhydrous silica), silica prepared by the wet method (hydrated silica), and other types commonly used in the tire industry can be used. Commercially available products from companies such as Evonik Industries, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Ltd., and Tokuyama Corporation can be used.

[0118] (ii) Silane coupling agent When using silica, it is preferable to use a silane coupling agent in combination to improve the dispersibility of silica and to enhance mechanical properties and moldability through reaction with silica.

[0119] The silane coupling agent is not particularly limited and includes, for example, bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)tri Sulfide, bis(3-triethoxysilylpropyl) disulfide, bis(2-triethoxysilylethyl) disulfide, bis(4-triethoxysilylbutyl) disulfide, bis(3-trimethoxysilylpropyl) disulfide, bis(2-trimethoxysilylethyl) disulfide, bis(4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide, 2-triethoxysilyl Examples of silane coupling agents include sulfide-based agents such as ethyl-N,N-dimethylthiocarbamoyl tetrasulfide and 3-triethoxysilylpropyl methacrylate monosulfide, mercapto-based agents such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and NXT and NXT-Z from Momentive, vinyl-based agents such as vinyltriethoxysilane and vinyltrimethoxysilane, amino-based agents such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane, glycidoxy-based agents such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane, nitro-based agents such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane, and chloro-based agents such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Among these, silane coupling agents having a thiocarbonyl group, such as NXT mentioned above, are preferred. These may be used alone or in combination of two or more.

[0120] Examples of silane coupling agents that can be used include products from Evonik Industries, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., and Toray Dow Corning Co., Ltd.

[0121] The silane coupling agent content is preferably more than 3 parts by mass, more preferably 5 parts by mass or more, and even more preferably 7 parts by mass or more, per 100 parts by mass of silica. The upper limit is preferably less than 15 parts by mass, more preferably 12 parts by mass or less, and even more preferably 9 parts by mass or less.

[0122] (iii) Carbon Black It is preferable to include carbon black in the tread rubber composition for the purpose of improving the tire's crack growth resistance, durability, and resistance to UV degradation.

[0123] The nitrogen adsorption specific surface area (N2SA) of carbon black is, from the perspective of its reinforcing properties for rubber, for example, 30m². 2 It is preferable that it be 50m or more / g 2 It is more preferable that it is 60m or more / g 2 It is even more preferable if it is 1 / g or more. On the other hand, from the viewpoint of exothermic properties, 250m 2 It is preferable that it be less than or equal to / g, and 150m 2 It is more preferable that it be less than or equal to / g, and 120m 2 It is even more preferable if the amount is less than or equal to / g. The specific surface area of ​​nitrogen adsorption of carbon black is measured according to ASTM D4820-93.

[0124] From the viewpoint of rubber rigidity, the amount of dibutyl phthalate (DBP) absorbed by carbon black is preferably 50 ml / 100g or more, and more preferably 100 ml / 100g or more. On the other hand, from the viewpoint of the rubber's ability to follow deformation, it is preferably 250 ml / 100g or less, and more preferably 150 ml / 100g or less. The DBP absorbed by carbon black is measured according to ASTM D2414-93.

[0125] Carbon black is not particularly limited and can include furnace blacks (furnace carbon blacks) such as SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF, and ECF; acetylene black (acetylene carbon black); thermal blacks (thermal carbon blacks) such as FT and MT; and channel blacks (channel carbon blacks) such as EPC, MPC, and CC. Part numbers can include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. These can be used individually or in combination of two or more types.

[0126] The raw materials for carbon black may be biomass materials other than mineral oil, such as lignin and vegetable oil, or pyrolysis oil obtained by thermally decomposing rubber products containing carbon black, such as waste tires (recycled carbon black). Using these sustainable carbon blacks is preferable from an environmental protection standpoint.

[0127] Furthermore, the method for producing carbon black may be by combustion such as the furnace process, by hydrothermal carbonization (HTC), or by thermal decomposition of methane such as the thermal black process.

[0128] Commercially available products from companies such as 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 Corporation can be used. These can be used individually or in combination of two or more types.

[0129] The carbon black content per 100 parts by mass of rubber component is preferably 3 parts by mass or more, and more preferably 5 parts by mass or more. As an upper limit, for example, it is preferably 15 parts by mass or less, and more preferably 10 parts by mass or less.

[0130] (iv) Other fillers In addition to the silica and carbon black mentioned above, the tread rubber composition may further contain fillers commonly used in the tire industry, such as graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, mica, and magnesium sulfate. The amount of these fillers is, for example, more than 0.1 parts by mass and less than 150 parts by mass per 100 parts by mass of the rubber component.

[0131] (b) Softening agent components In rubber compositions, it is preferable to use a softening agent component as needed, taking into consideration the proper dispersion of powder materials during mixing. Here, the softening agent component refers to a material that imparts plasticity to the rubber component, and is a concept that includes both liquid softening agents at 25°C and solid softening agents at 25°C.

[0132] Examples of softeners include resin components, oils, liquid polymers, and ester-based plasticizers. These softeners may be derived from mineral resources such as petroleum and natural gas, from biomass, or from naphtha recycled from rubber or non-rubber products. In addition, low molecular weight hydrocarbon components obtained by thermal decomposition and extraction of used tires or products containing various components may be used as softeners. Among these, softeners derived from biomass or recycled materials are preferred as sustainable softeners.

[0133] These softening agents may be used individually or in combination of two or more. The content of the plasticizer component per 100 parts by mass of rubber component is preferably 30 parts by mass or more, and more preferably 35 parts by mass or more. The upper limit is preferably 45 parts by mass or less, and more preferably 40 parts by mass or less. The content of the plasticizer component also includes the amount of oil contained in the rubber (oil-applied rubber), etc.

[0134] (i) oil Examples of oils include mineral oil, vegetable oil, and animal oil. From a life cycle assessment perspective, waste oil used in rubber mixers and engines, or refined waste cooking oil used in restaurants, may also be used.

[0135] (i-1) Mineral oil Mineral oil refers to oil derived from mineral resources such as petroleum and natural gas. Examples of mineral oil include paraffinic oils (mineral oil), naphthenic oils, and aromatic oils.

[0136] Specific examples of mineral oils include MES (Mild Extract Solvated), DAE (Distillate Aromatic Extract), TDAE (Treated Distillate Aromatic Extract), TRAE (Treated Residual Aromatic Extract), and RAE (Residual Aromatic Extract).

[0137] Furthermore, for environmental reasons, oils with a low content of polycyclic aromatic compounds (PCA) can be used. Examples of such low-PCA oils include MES, TDAE, and heavy naphthenic oils.

[0138] Examples of commercially available mineral oils include paraffinic, aromatic, and naphthenic oils. Products from companies such as Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Showa Shell Sekiyu K.K., and Fuji Kosan Co., Ltd. can be used. These can be used individually or in combination of two or more types.

[0139] (i-2) Vegetable oil Examples of vegetable oils include linseed oil, rapeseed oil, safflower oil, soybean oil, corn oil, cottonseed oil, rice bran oil, tall oil, sesame oil, perilla oil, castor oil, tung oil, pine oil, pine tar oil, sunflower oil, coconut oil, palm oil, palm kernel oil, olive oil, camellia oil, jojoba oil, macadamia nut oil, peanut oil, grapeseed oil, and wood wax.

[0140] Furthermore, vegetable oils can also include refined oils (such as salad oil) obtained by refining the above-mentioned oils, transesterified oils obtained by transesterification, hydrogenated oils obtained by hydrogenation, thermally polymerized oils obtained by thermal polymerization, oxidized polymerized oils obtained by oxidation, and waste cooking oils recovered from use as cooking oil. Vegetable oils may be liquid or solid at room temperature (25°C). These may be used individually or in combination of two or more types.

[0141] The vegetable oil preferably contains acylglycerol, and more preferably contains triacylglycerol. Acylglycerol refers to a compound in which a hydroxyl group of glycerin is esterified with a fatty acid. The acylglycerol is not particularly limited and may be 1-monoacylglycerol, 2-monoacylglycerol, 1,2-diacylglycerol, 1,3-diacylglycerol, or triacylglycerol. Furthermore, the acylglycerol may be a monomer, a dimer, or a polymer of three or more. Acylglycerols of two or more can be obtained by thermal polymerization, oxidative polymerization, etc. Also, the acylglycerol may be a liquid or a solid at room temperature (25°C).

[0142] There are no particular limitations on the method for determining whether a rubber composition contains acylglycerol, 1 This can be confirmed by 1H-NMR measurement. 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, it is measured at room temperature. 1When 1H-NMR is measured and the signal for tetramethylsilane (TMS) is set to 0.00 ppm, signals around 5.26 ppm, 4.28 ppm, and 4.15 ppm are observed. These signals are presumed to originate from hydrogen atoms bonded to carbon atoms adjacent to the oxygen atom of the ester group, thus confirming the presence of acylglycerol. Here, "around" refers to a range of ±0.10 ppm.

[0143] The fatty acids are not particularly limited and may be either unsaturated or saturated fatty acids. 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.

[0144] In particular, it is desirable that the fatty acid contains fatty acids with few double bonds, i.e., saturated fatty acids or monounsaturated fatty acids, and oleic acid is preferred. As a vegetable oil containing such fatty acids, for example, a vegetable oil containing saturated fatty acids or monounsaturated fatty acids may be used, or a vegetable oil that has been modified by transesterification or other means may be used. Furthermore, in order to produce a vegetable oil containing such fatty acids, plants may be improved by breeding, genetic modification, genome editing, etc.

[0145] As for vegetable oils, commercially available products from companies such as Idemitsu Kosan Co., Ltd., Sankyo Yuka Kogyo Co., Ltd., ENEOS Corporation, Orisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Fuji Kosan Co., Ltd., and Nisshin Oillio Group Ltd. can be used.

[0146] (ii) Liquid rubber Liquid rubber is a polymer that is in a liquid state at room temperature (25°C) and is a rubber component that can be extracted from vulcanized tires by acetone extraction. Examples of liquid rubber include farnesene polymers, liquid diene polymers, and their hydrogenated derivatives.

[0147] Farnesene polymers are polymers obtained by polymerizing farnesene and have constituent units based on farnesene. Farnesene has isomers such as α-farnesene ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodecatetraene) and β-farnesene (7,11-dimethyl-3-methylene-1,6,10-dodecatriene).

[0148] The farnesene polymer may be a farnesene homopolymer (farnesene homopolymer) or a farnesene-vinyl monomer copolymer (farnesene-vinyl monomer copolymer).

[0149] Examples of liquid diene polymers include liquid styrene-butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), and liquid styrene-isoprene copolymer (liquid SIR).

[0150] The liquid diene polymer has a weight-average molecular weight (Mw) on a polystyrene basis, measured by gel permeation chromatography (GPC), for example, 1.0 × 10⁻⁶. 3 Super, 2.0×10 5 It is less than [value]. Here, the Mw of the liquid diene polymer is the polystyrene equivalent value measured by gel permeation chromatography (GPC).

[0151] As for liquid rubber, products from companies such as Kuraray Co., Ltd. and Clay Valley Corporation can be used.

[0152] (iii) Resin components The resin component also functions as a tackifying agent and may be solid or liquid at room temperature. Specific examples of resin components include rosin resins, styrene resins, coumarone resins, terpene resins, C5 resins, C9 resins, C5C9 resins, and acrylic resins, and two or more may be used in combination. These resin components may also be modified to include silica or other reactive groups as needed.

[0153] Rosin resins are resins whose main component is rosin acid, obtained by processing pine resin. These rosin resins (rosins) can be classified according to whether or not they are modified, and can be classified into unmodified rosin and rosin derivatives. Examples of unmodified rosin include tall rosin (also known as tall oil rosin), gum rosin, wood rosin, disproportionate rosin, polymerized rosin, hydrogenated rosin, and other chemically modified rosins. Rosin derivatives are modified forms of unmodified rosin and include rosin esters, unsaturated carboxylic acid-modified rosins, unsaturated carboxylic acid-modified rosin esters, rosin amide compounds, and rosin amine salts.

[0154] Styrene resins are polymers that use styrene monomers as constituent monomers, and include polymers polymerized with styrene monomers as the main component (50% by mass or more). Specifically, examples include homopolymers obtained by polymerizing styrene monomers (styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc.) individually, copolymers obtained by copolymerizing two or more styrene monomers, and copolymers of styrene monomers and other monomers that can copolymerize with them.

[0155] Examples of the aforementioned other monomers include acrylonitriles such as acrylonitrile and methacrylonitrile, unsaturated carboxylic acids such as acrylics and methacrylic acid, unsaturated carboxylic acid esters such as methyl acrylate and methyl methacrylate, dienes such as chloroprene and butadiene isoprene, olefins such as 1-butene and 1-pentene; α,β-unsaturated carboxylic acids such as maleic anhydride or their acid anhydrides; and so on.

[0156] Among coumarone-based resins, coumarone-indene resin is preferred. Coumarone-indene resin is a resin that contains coumarone and indene as monomer components that constitute the resin's backbone (main chain). Other monomer components that can be included in the backbone besides coumarone and indene include styrene, α-methylstyrene, methylindene, and vinyltoluene.

[0157] The hydroxyl value (OH value) of coumarone indene resin is, for example, greater than 15 mg KOH / g and less than 150 mg KOH / g. The OH value is expressed in milligrams as the amount of potassium hydroxide required to neutralize the acetic acid bonded to the hydroxyl groups when acetylating 1 g of resin, and is measured by potentiometric titration (JIS K 0070:1992).

[0158] The softening point of coumaron indene resin is, for example, above 30°C and below 160°C. The softening point is determined by measuring the softening point as specified in JIS K 6220-1:2001 using a ring-type softening point measuring device, and it is the temperature at which the sphere descends.

[0159] Examples of terpene resins include polyterpenes, terpene phenols, and aromatically modified terpene resins. Polyterpenes are resins obtained by polymerizing terpene compounds and their hydrogenated products. Terpene compounds are (C5H8) n A hydrocarbon represented by the following composition and its oxygen-containing derivative, a monoterpene (C 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpene (C 20 H 32 These are compounds with a terpene as their basic skeleton, classified as such, and examples include α-pinene, β-pinene, dipentene, limonene, myrcene, allocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, and γ-terpineol.

[0160] Polyterpenes include terpene resins such as α-pinene resin, β-pinene resin, limonene resin, dipentene resin, and β-pinene / limonene resin, which are made from the terpene compounds mentioned above, as well as hydrogenated terpene resins obtained by hydrogenating these terpene resins. Terpene phenols include resins obtained by copolymerizing the above terpene compounds with phenolic compounds, and resins obtained by hydrogenating these resins. Specifically, resins obtained by condensing the above terpene compounds, phenolic compounds, and formalin are included. Examples of phenolic compounds include phenol, bisphenol A, cresol, and xylenol. Aromatically modified terpene resins include resins obtained by modifying terpene resins with aromatic compounds, and resins obtained by hydrogenating these resins. The aromatic compounds are not particularly limited as long as they are compounds having an aromatic ring, but examples include phenol compounds such as phenol, alkylphenol, alkoxyphenol, and phenol containing an unsaturated hydrocarbon group; naphthol compounds such as naphthol, alkylnaphthol, alkoxynaphthol, and naphthol containing an unsaturated hydrocarbon group; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, and styrene containing an unsaturated hydrocarbon group; coumarone, indene, and others.

[0161] "C5 resin" refers to a resin obtained by polymerizing a C5 fraction. Examples of C5 fractions include petroleum fractions with 4 to 5 carbon atoms, such as cyclopentadiene, pentene, pentadiene, and isoprene. Dicyclopentadiene resin (DCPD resin) is preferably used as a C5-based petroleum resin.

[0162] "C9 resin" refers to a resin obtained by polymerizing a C9 fraction, and may be hydrogenated or modified. Examples of C9 fractions include petroleum fractions with 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, and methylindene. Specific examples include coumarone indene resin, coumarone resin, indene resin, and aromatic vinyl resins, which are suitably used. As aromatic vinyl resins, α-methylstyrene (AMS resin), a homopolymer of styrene, or a copolymer of α-methylstyrene and styrene is preferred, and a copolymer of α-methylstyrene and styrene is more preferred, due to their economical nature, ease of processing, and excellent heat generation properties. Aromatic vinyl resins that are commercially available from companies such as Kraton and Eastman Chemical can be used.

[0163] "C5C9 resin" refers to a resin obtained by copolymerizing the C5 fraction and the C9 fraction, and may be hydrogenated or modified. Examples of the C5 and C9 fractions include the petroleum fractions mentioned above. As for the C5C9 resin, commercially available products from companies such as Tosoh Corporation and LUHUA can be used.

[0164] While there are no particular limitations on the acrylic resin used, for example, a solvent-free acrylic resin can be used.

[0165] Solvent-free acrylic resins include (meth)acrylic resins (polymers) synthesized by high-temperature continuous polymerization (high-temperature continuous mass polymerization) (methods described in U.S. Patent No. 4,414,370, Japanese Patent Publication No. 59-6207, Japanese Patent Publication No. 5-58005, Japanese Patent Publication No. 1-313522, U.S. Patent No. 5,010,166, Toa Gosei Research Annual Report TREND2000 No. 3 pp. 42-45, etc.) with minimal use of polymerization initiators, chain transfer agents, organic solvents, etc. as auxiliary raw materials. In this invention, (meth)acrylic means methacrylic and acrylic.

[0166] Examples of monomer components constituting the above-mentioned acrylic resin include (meth)acrylic acid, (meth)acrylic acid esters (alkyl esters, aryl esters, aralkyl esters, etc.), (meth)acrylamide, and (meth)acrylic acid derivatives such as (meth)acrylamide derivatives.

[0167] Furthermore, as monomer components constituting the above-mentioned acrylic resin, aromatic vinyls such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, and divinylnaphthalene may be used along with (meth)acrylic acid and (meth)acrylic acid derivatives.

[0168] The above-mentioned acrylic resin may be a resin composed solely of (meth)acrylic components, or it may be a resin that also contains components other than (meth)acrylic components. Furthermore, the above-mentioned acrylic resin may have hydroxyl groups, carboxyl groups, silanol groups, etc.

[0169] As resin components, products from companies such as Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Kraton Chemicals, Nippon Paint Chemicals Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Corporation, Arakawa Chemical Industries, Ltd., and Taoka Chemical Industries, Ltd. can be used.

[0170] (H) Wax The rubber composition may contain wax. The wax content is preferably, for example, 0.5 to 20 parts by mass, more preferably 1.0 to 15 parts by mass, and even more preferably 1.5 to 10 parts by mass, per 100 parts by mass of the rubber component.

[0171] The wax used is not particularly limited, and any wax commonly used in the tire industry can be suitably used. Examples include mineral waxes and plant-derived waxes. Mineral waxes refer to waxes derived from mineral resources such as oil and natural gas. Plant-derived waxes refer to waxes derived from natural resources such as plants. Among these, mineral waxes are preferred.

[0172] 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 specialty waxes thereof, with paraffin wax being preferred. In this invention, the wax does not contain stearic acid.

[0173] For example, commercially available waxes from companies such as Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Paramelt Co., Ltd. can be used. These waxes may be used individually or in combination of two or more types.

[0174] (ii) Anti-aging agents The rubber composition may contain an antioxidant. The amount of the antioxidant is, for example, more than 1 part by mass and less than 10 parts by mass per 100 parts by mass of the rubber component.

[0175] While not particularly limited, examples of anti-aging agents include naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; 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'-ditril-p-phenylenediamine. Examples include p-phenylenediamine-based antioxidants such as methyl amine (DTPD), N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), and N,N'-di-2-naphthyl-p-phenylenediamine (DNPD); quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based antioxidants such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis-, tris-, and polyphenol-based antioxidants such as tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane. Among these, p-phenylenediamine-based antioxidants and quinoline-based antioxidants are preferred, and polymers of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. These may be used individually or in combination of two or more.

[0176] Commercially available products include those from companies such as Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Industry Co., Ltd., and Flexis.

[0177] (e) Processing aids The rubber composition may contain processing aids. Examples of processing aids include metal salts (compounds in which the hydrogen atoms of an acid are replaced by metal ions), fatty acid amides, amide esters, and fatty acid esters. These may be used alone or in combination of two or more. Among these, metal salts and fatty acid amides are preferred, and metal salts are more preferred.

[0178] Examples of metals used in metal salts include alkali metals such as potassium and sodium, and alkaline earth metals such as calcium and barium. Magnesium, zinc, nickel, and molybdenum can also be used. Among these, alkali metals are preferred.

[0179] Acids used in metal salts include fatty acids such as lauric acid, myristic acid, and palmitic acid. Boric acid, carbonic acid, hydrochloric acid, nitric acid, and sulfuric acid can also be used.

[0180] Commercially available processing aids include products from companies such as Kishida Chemical Co., Ltd., Ken-ei Pharmaceutical Co., Ltd., Structol, and Performance Additives.

[0181] The content of the processing aid is preferably 1 part by mass or more, and more preferably 2 parts by mass or more, per 100 parts by mass of the rubber component. As an upper limit, for example, it is preferably 6 parts by mass or less, and more preferably 4 parts by mass or less.

[0182] (H) Lubricant (Stearic Acid) The rubber composition may contain a lubricant. Fatty acid derivative-based lubricants, such as stearic acid, are preferably used. Conventional known stearic acid products can be used; specifically, products from companies such as NOF Corporation, NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Industries Ltd., and Chiba Fatty Acid Co., Ltd. can be used. Furthermore, products such as Structol WB16 manufactured by Structol Corporation can also be used.

[0183] The stearic acid content is preferably, for example, more than 0.5 parts by mass and less than 10.0 parts by mass per 100 parts by mass of the rubber component.

[0184] (t) Zinc oxide The rubber composition may contain zinc oxide. The zinc oxide content is, for example, more than 0.5 parts by mass and less than 10 parts by mass per 100 parts by mass of the rubber component. Conventional known zinc oxides can be used, such as products from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc.

[0185] (h) Crosslinking agents and vulcanization accelerators The rubber composition preferably contains a crosslinking agent such as sulfur. The crosslinking agent content is, for example, more than 0.1 parts by mass and less than 10.0 parts by mass per 100 parts by mass of the rubber component. The sulfur content refers to the amount of pure sulfur, and if insoluble sulfur is used, it is the content excluding the oil content.

[0186] Examples of sulfur commonly used in the rubber industry include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur. These may be used individually or in combination of two or more types.

[0187] For sulfur, products from companies such as Tsurumi Chemical Industries, Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemicals Co., Ltd., Flexis Co., Ltd., Nippon Dry Distillation Co., Ltd., and Hosoi Chemical Industries Co., Ltd. can be used.

[0188] Other crosslinking agents besides sulfur may be used. Specifically, for example, sulfur-containing vulcanizing agents such as Takkirol V200 from Taoka Chemical Industries, Ltd., DURALINK HTS (1,6-hexamethylene-dithiosulfate sodium dihydrate) from Flexis, and KA9188 (1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane: hybrid crosslinking agent) from Lanxess, as well as organic peroxides such as dicumyl peroxide, can be used.

[0189] Furthermore, the rubber composition preferably contains a vulcanization accelerator. The amount of vulcanization accelerator is, for example, more than 0.3 parts by mass and less than 10.0 parts by mass per 100 parts by mass of the rubber component.

[0190] Examples of vulcanization accelerators include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiadylsulfenamide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazolesulfenamide, Nt-butyl-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, and N,N'-diisopropyl-2-benzothiazolesulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, diortotrilguanidine, and orthotrilbiguanidine. These can be used individually or in combination of two or more.

[0191] (Ri) Others In addition to the components described above, the rubber composition may also contain additives commonly used in the tire industry, such as organic fillers like cellulose fibers and organic peroxides, as needed. The content of these additives is, for example, more than 0.1 parts by mass and less than 50 parts by mass per 100 parts by mass of the rubber component.

[0192] In this invention, among the materials described above, various materials containing carbon atoms (for example, rubber, oil, resin, vulcanization accelerator, antioxidant, surfactant, etc.) may be derived from carbon dioxide in the atmosphere. As a method for obtaining the formulation of this invention from carbon dioxide, carbon dioxide may be converted directly, or methane obtained through a methanation process in which methane is synthesized from carbon dioxide may be converted.

[0193] (2) Preparation of rubber composition for tread A rubber composition for treads can be produced by a general method, for example, a manufacturing method that includes a base mixing step of mixing rubber components with fillers such as silica, and a finish mixing step of mixing the mixture obtained in the base mixing step with a crosslinking agent.

[0194] Mixing can be carried out using known (closed) mixers such as Banbury mixers, kneaders, and open roll mixers.

[0195] The mixing temperature in the base mixing process is, for example, more than 50°C and less than 200°C, and the mixing time is, for example, more than 30 seconds and less than 30 minutes. In the base mixing process, in addition to the above components, compounding agents conventionally used in the rubber industry, such as softeners such as oils, stearic acid, zinc oxide, antioxidants, waxes, and vulcanization accelerators, may be added and mixed as needed.

[0196] In the final mixing step, the mixture obtained in the base mixing step is mixed with the crosslinking agent. The mixing temperature in the final mixing step is, for example, above room temperature but below 80°C, and the mixing time is, for example, more than 1 minute but less than 15 minutes. In the final mixing step, in addition to the above components, vulcanization accelerators, zinc oxide, etc., may be added and mixed as needed.

[0197] The rubber composition obtained as described above can then be molded into a tread by extruding it into a predetermined shape.

[0198] 3. Tire manufacturing The tire according to this embodiment can be manufactured by conventional methods. First, the rubber composition obtained above is molded into a predetermined shape to produce a tread. Next, it is combined with other rubber components on a tire molding machine to produce an unvulcanized tire.

[0199] Specifically, an inner liner as a component to ensure the airtightness of the tire, a carcass as a component to withstand the load, impact, and air pressure of the tire, and belt members and bands as components to tightly fasten the carcass and increase the rigidity of the tread are wound around a molding drum, and both ends of the carcass are fixed to both side edges, and a bead portion is placed as a component to fix the tire to the rim, and after forming it into a toroid shape, the tread is bonded to the center of the outer circumference and the sidewall is bonded to the radially outer side to form the side portion, thereby producing an unvulcanized tire.

[0200] Subsequently, the unvulcanized tire produced as described above is heated and pressurized in a vulcanizing machine to obtain a tire. The vulcanization process can be carried out by applying known vulcanization methods. The vulcanization temperature is, for example, greater than 120°C and less than 200°C, and the vulcanization time is, for example, greater than 5 minutes and less than 15 minutes.

[0201] As mentioned above, the resulting tire uses PET bands as band cords, forms a carcass appropriately, and uses a properly formulated tread rubber composition to form the tread. Furthermore, because each of the above parameters is appropriately controlled, it is possible to further improve fuel efficiency.

[0202] Furthermore, the tire according to the present invention can be suitably used as a passenger car tire, a large passenger car tire, a large SUV tire, a truck / bus tire, a motorcycle tire, a racing tire, a studless tire (winter tire), an all-season tire, a run-flat tire, etc., and is particularly preferred as a passenger car tire. [Examples]

[0203] The following examples (implementations) are considered preferable for implementation, but the scope of the present invention is not limited to these examples.

[0204] We examined a tire (tire size: 235 / 55R19) consisting of a tread molded from the various compound materials listed below, as well as tire components such as bands, belts, and carcasses. The results calculated based on the evaluation method for fuel efficiency described later are shown in the lower part of Tables 2 and 3.

[0205] 1. Preparation of rubber composition A rubber composition for the tread is prepared using the following compounding materials.

[0206] (1) Compounding materials (a) Rubber component (i) NR: TSR20 (b) SBR-1: HPR850 (modified S-SBR) manufactured by ENEOS Material Corporation (Styrene content: 26% by mass, vinyl content: 59% by mass, Tg: -25℃, non-oil extended product) (h) SBR-2: Modified S-SBR manufactured based on manufacturing example 1 described later. (Styrene content: 33% by mass, vinyl content: 46% by mass, Tg: -34℃, non-oil extended product) (ii) SBR-3: Modified S-SBR manufactured based on manufacturing example 2 described later. (Styrene content: 25% by mass, vinyl content: 17% by mass, Tg: -54℃, non-oil extended product) (e) BR: BR150B manufactured by Ube Industries (cis content: 96% by mass)

[0207] (Manufacturing Example 1) The above SBR-2 is prepared according to the following procedure. First, cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene are charged into a nitrogen-purged autoclave reactor. After adjusting the temperature of the reactor contents to 20°C, n-butyllithium is added to start polymerization. Polymerization is then carried out under adiabatic conditions, and when the maximum temperature reaches 85°C and the polymerization conversion rate reaches 99%, 1,3-butadiene is added and polymerization is carried out for a further 5 minutes. Then, a mixture of tetraglycidyl-1,3-bisaminomethylcyclohexane (monomer) and the oligomer component is added as a modifier and the reaction is carried out. After the polymerization reaction is complete, 2,6-di-tert-butyl-p-cresol is added, the solvent is removed by steam stripping, and the mixture is dried with a heated roller at 110°C to obtain SBR-2.

[0208] (Manufacturing example 2) The above SBR-3 is prepared in the same manner as in Production Example 1, except that N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane is used as a denaturing agent.

[0209] (b) Compounding materials other than rubber components (i) Carbon Black-1: Show Black N220 manufactured by Cabot Japan (N2SA:111m 2 / g) (b) Carbon Black-2: Seast SO (FEF) manufactured by Tokai Carbon Co., Ltd. (N2SA:42m 2 / g) (h) Silica-1: Ultrasil VN3 manufactured by Eponic Industries (N2SA:175m 2 / g, average primary particle diameter: 17nm) (ii) Silica-2: UltraSil 5000GR manufactured by Eponic Industries. (N2SA:115m 2 / g, average primary particle diameter: 21nm) (e) Silane coupling agent-1: Si266 manufactured by Evonik Industries (Bis(3-triethoxysilylpropyl) disulfide) (H) Silane coupling agent-2: NXT Z 45 manufactured by Momentive (3-Octanoylthiopropyltriethoxysilane) (T) Oil: H&R Vivatec 500 (TDAE, Aromatic Process Oil) (C) Resin: Sylvatraxx 4401 manufactured by Kraton Corporation (A copolymer of α-methylstyrene and styrene) (Re)wax: Ozoace 0355 (paraffin wax) manufactured by Nippon Seiro Co., Ltd. (Nu) Anti-aging agent-1: Nocrack 6C manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (N-(1,3-dimethylbutyl)-N'phenyl-p-phenylenediamine) (L) Anti-aging agent-2: Anti-aging agent manufactured by Kawaguchi Chemical Industry Co., Ltd. (2,2,4-trimethyl-1,2-dihydroquinoline) (W) Stearic acid: NOF Corporation's bead stearic acid "Tsubaki" (W) Zinc oxide: Zinc oxide No. 1 manufactured by Mitsui Mining & Smelting Co., Ltd. (c) Sulfur: HK-200-5 (powdered sulfur) manufactured by Hosoi Chemical Industry Co., Ltd. (Yo) Vulcanization accelerator-1: Noxellar CZ manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS)) (T) Vulcanization accelerator-2: Noxellar D manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (N,N'-diphenylguanidine (DPG))

[0210] (2) Preparation of rubber composition for tread Based on the formulations A to F shown in Table 1, the materials other than sulfur and vulcanization accelerator were kneaded for 5 minutes at 150°C using a 1.7L Banbury mixer manufactured by Kobe Steel, Ltd. to obtain a kneaded product.

[0211] Next, sulfur and a vulcanization accelerator are added to the mixture, and it is kneaded using an open roll at 80°C for 5 minutes to obtain tread rubber compositions A to F.

[0212] [Table 1]

[0213] 2. Molding of tire components (tread, band, belt) (1) Tread molding Next, using the rubber composition obtained above, treads (cap treads) are molded at the thicknesses shown in Tables 2 and 3.

[0214] (2) Forming the band In parallel, the band cords shown in Tables 2 and 3 are topped with the specified rubber composition for bands to form each band.

[0215] (3) Forming of the belt Similarly, each belt is formed by topping each belt cord shown in Tables 2 and 3 with the specified belt rubber composition.

[0216] (4) Forming the carcass Similarly, each carcass is formed by topping each carcass cord shown in Tables 2 and 3 with the predetermined carcass rubber composition.

[0217] 3. Tire manufacturing Next, the treads, bands, belts, and carcasses obtained above are bonded together with other tire components to form an unvulcanized tire, which is then press-vulcanized at 170°C for 10 minutes to produce the test tires (outer diameter Dt: 741.1 mm) for Examples 1 to 9 and Comparative Examples 1 to 5.

[0218] 4. Performance evaluation test (evaluation of fuel efficiency) Using a rolling resistance tester, the rolling resistance coefficient (RRC) of each test tire is measured when it travels on a drum at a speed of 80 km / h under the following conditions. Rim used: 19×7.5J Internal pressure: 210kPa Load: 6.47 kN

[0219] Next, taking the result in Comparative Example 1 as 100, it is indexed based on the following formula for fuel consumption performance evaluation. The larger the value, the smaller the rolling resistance and the better the fuel consumption performance. Fuel consumption performance evaluation = [(Result of Comparative Example 1) / (Result of test tire)] × 100

[0220] [Table 2]

[0221] [Table 3]

[0222] As described above, the present invention has been described based on the embodiments, but the present invention is not limited to the above embodiments. Various modifications can be made to the above embodiments within the same and equivalent scope as the present invention.

[0223] The present invention (1) is a carcass including carcass cords, a belt including belt cords provided on the outer side in the tire radius direction of the carcass, a band including band cords provided on the outer side in the tire radius direction of the belt, a tire including a tread provided on the outer side in the tire radius direction of the band, wherein the carcass has a two-layer structure of a first carcass ply and a second carcass ply each including carcass cords, and is formed by winding around the bead, the band cords are band cords containing polyethylene terephthalate fibers, the tread is formed using a rubber composition containing more than 75 parts by mass of silica with respect to 100 parts by mass of the rubber component and having an acetone extract content of more than 15% by mass, Furthermore, when the outer diameter of the tire is Dt (mm), the height of the first carcass ply located on the outside when the carcass is wound up is P1 (mm), and the height of the second carcass ply located on the inside is P2 (mm), the following (Equation 1) is satisfied, The tire is characterized by satisfying the following equation (Equation 2), where D1 (mm) is the diameter of the band cord, D2 (mm) is the diameter of the belt cord, and D3 (mm) is the diameter of the carcass cord. (P1-P2) / Dt<0.07 (Equation 1) (D1+D2+D3)<2.00 (Equation 2)

[0224] The present invention (2) is, The tire is characterized in that the above ((P1-P2) / Dt) is less than 0.067, and is the tire described in (1) of the present invention.

[0225] The present invention (3) is, The tire is characterized in that the above ((P1-P2) / Dt) is less than 0.065, and is the tire described in (2) of the present invention.

[0226] The present invention (4) is, The tire is characterized in that the above ((P1-P2) / Dt) is less than 0.063, and is the tire described in (3) of the present invention.

[0227] The present invention (5) is, The above (D1+D2+D3) is characterized by being less than 1.80, and is a tire in any combination with any of the present invention (1) to (4).

[0228] The present invention (6) is, The tire is characterized in that (D1+D2+D3) is less than 1.70, as described in (5) of the present invention.

[0229] The present invention (7) is, The rubber composition is characterized in that the silica content is more than 80 parts by mass per 100 parts by mass of rubber components, and is a tire in any combination with any of the present invention (1) to (4).

[0230] The present invention (8) is characterized in that the silica content in the rubber composition exceeds 90 parts by mass with respect to 100 parts by mass of the rubber component, and is the tire according to the present invention (7).

[0231] The present invention (9) is characterized in that the silica content in the rubber composition exceeds 100 parts by mass with respect to 100 parts by mass of the rubber component, and is the tire according to the present invention (8).

[0232] The present invention (10) is characterized in that the acetone extract in the rubber composition exceeds 17% by mass, and is a tire in any combination of the present inventions (1) to (4).

[0233] The present invention (11) is characterized in that the thickness of the tread exceeds 6 mm, and is a tire in any combination of the present inventions (1) to (4).

[0234] The present invention (12) is characterized in that the tread is composed of two layers, and is a tire in any combination of the present inventions (1) to (4).

[0235] The present invention (13) is characterized in that the rubber composition contains more than 25 parts by mass of isoprene rubber in 100 parts by mass of the rubber component, and is a tire in any combination of the present inventions (1) to (4).

[0236] The present invention (14) is characterized in that the isoprene rubber is natural rubber, and is the tire according to the present invention (13).

[0237] The present invention (15) is The rubber composition is characterized in that the loss loss tangent (30°C tanδ), measured in tensile deformation mode under the conditions of 30°C, frequency of 10Hz, initial strain of 5%, and dynamic strain of 1%, is less than 0.19, and is a tire in any combination with any of the present invention (1) to (4).

[0238] The present invention (16) is, The aforementioned belt cord is characterized by being composed of one to four filaments, and is a tire in any combination with any of the present invention (1) to (4).

[0239] The present invention (17) is, The aforementioned polyethylene terephthalate fiber is characterized by being a sustainable PET fiber, and the tire is any combination of (1) to (4) of the present invention.

[0240] The present invention (18) is, The rubber composition is characterized by containing vegetable oil, and is a tire in any combination with any of the present invention (1) to (4).

[0241] The present invention (19) is, The rubber composition is characterized by containing sustainable carbon black, and is a tire in any combination with any of the present invention (1) to (4).

[0242] The present invention (20) is, The rubber composition is characterized by containing sustainable silica, and is a tire in any combination with any of the present invention (1) to (4). [Explanation of Symbols]

[0243] 1 tire 2 tread 3 Sidewall 4 Chafers 5 Beads 6. Inner Liner 7 Carcass 7A First Carcass Ply 7B Second Carcass Ply 8 belts 9 Filler 10 bands CL tire equatorial plane

Claims

1. A carcass equipped with a carcass cord, A belt cord is provided, and the belt is provided on the radially outer side of the carcass, A band cord is provided, and the band is provided on the radially outer side of the belt in the tire direction, A tire comprising a tread provided on the radially outer side of the band, The carcass has a two-layer structure consisting of a first carcass ply and a second carcass ply, each equipped with a carcass cord, and is formed by winding around the bead. The aforementioned band cord is a band cord containing polyethylene terephthalate fibers, The tread is formed using a rubber composition containing more than 75 parts by mass of silica per 100 parts by mass of rubber component, and more than 15% by mass of acetone extract. Furthermore, when the outer diameter of the tire is Dt (mm), the height of the first carcass ply located on the outside when the carcass is wound up is P1 (mm), and the height of the second carcass ply located on the inside is P2 (mm), the following (Equation 1) is satisfied, A tire characterized by satisfying the following equation (Equation 2), where D1 (mm) is the diameter of the band cord, D2 (mm) is the diameter of the belt cord, and D3 (mm) is the diameter of the carcass cord. (P1-P2) / Dt<0.07 (Formula 1) (D1+D2+D3)<2.00 (Formula 2)

2. The tire according to claim 1, characterized in that the ((P1 - P2) / Dt) is less than 0.

067.

3. The tire according to claim 2, characterized in that the ((P1 - P2) / Dt) is less than 0.

065.

4. The tire according to claim 3, characterized in that the ((P1 - P2) / Dt) is less than 0.

063.

5. The tire according to any one of claims 1 to 4, characterized in that the (D1 + D2 + D3) is less than 1.

80.

6. The tire according to claim 5, characterized in that (D1 + D2 + D3) is less than 1.

70.

7. The tire according to any one of claims 1 to 4, characterized in that the silica content in the rubber composition is more than 80 parts by mass per 100 parts by mass of the rubber component.

8. The tire according to claim 7, characterized in that the silica content in the rubber composition is more than 90 parts by mass per 100 parts by mass of rubber component.

9. The tire according to claim 8, characterized in that the silica content in the rubber composition is more than 100 parts by mass per 100 parts by mass of rubber component.

10. The tire according to any one of claims 1 to 4, characterized in that the acetone extract in the rubber composition is greater than 17% by mass.

11. The tire according to any one of claims 1 to 4, characterized in that the thickness of the tread is greater than 6 mm.

12. The tire according to any one of claims 1 to 4, characterized in that the tread is composed of two layers.

13. The tire according to any one of claims 1 to 4, characterized in that the rubber composition contains more than 25 parts by mass of isoprene-based rubber in 100 parts by mass of rubber component.

14. The tire according to claim 13, characterized in that the isoprene-based rubber is natural rubber.

15. The tire according to any one of claims 1 to 4, characterized in that the loss tangent (30°C tanδ) of the rubber composition, measured in tensile deformation mode under the conditions of 30°C, frequency of 10 Hz, initial strain of 5%, and dynamic strain of 1%, is less than 0.

19.

16. The tire according to any one of claims 1 to 4, characterized in that the belt cord is composed of one or more and four or fewer filaments.

17. The tire according to any one of claims 1 to 4, characterized in that the polyethylene terephthalate fiber is a sustainable PET fiber.

18. The tire according to any one of claims 1 to 4, characterized in that the rubber composition contains vegetable oil.

19. The tire according to any one of claims 1 to 4, characterized in that the rubber composition contains sustainable carbon black.

20. The tire according to any one of claims 1 to 4, characterized in that the rubber composition contains sustainable silica.

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