tire

Abstract

To improve tire durability at high speeds. [Solution] A tire comprising a carcass, a belt provided on the radially outer side of the carcass, a band cord, a band provided on the radially outer side of the belt, and a tread provided on the radially outer side of the band, wherein the band cord is a sustainable polyester cord, the cord diameter of the band cord is d (mm), the number of cords present in the 5 cm direction perpendicular to the longitudinal direction is D (cords / 5 cm), the dimensional stability index is DSI (%), the loss loss tangent measured under the conditions of a tread temperature of 30°C, initial strain of 5%, dynamic strain of 1%, frequency of 10 Hz, deformation mode: tensile is 30°C tanδ, and the thickness of the tread is A (mm), satisfying the following formula (1). (d×D) / (DSI×30℃tanδ×A)≧0.7

Description

Technical Field

[0001] The present invention relates to a tire.

Background Art

[0002] In a passenger car tire, as in Patent Document 1, generally, a band (also called a cap ply) is provided as a belt reinforcing layer between a tread and a belt from the viewpoint of preventing deformation of the tire due to centrifugal force during high-speed driving.

Prior Art Documents

Patent Documents

[0006] According to the present invention, it is possible to improve the durability of tires during high-speed driving. [Brief explanation of the drawing]

[0007] [Figure 1] 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, a belt provided on the radially outer side of the carcass, and a band cord, a band provided on the radially outer side of the belt, and a tread provided on the radially outer side of the band. The band cord is a sustainable polyester cord. Furthermore, when the cord diameter of the band cord is d (mm), the number of cords present in the direction perpendicular to the longitudinal direction at 5 cm is D (cords / 5 cm), the dimensional stability index is DSI (%), the loss loss tangent measured under conditions of tread temperature of 30°C, initial strain of 5%, dynamic strain of 1%, frequency of 10 Hz, deformation mode: tensile is 30°C tanδ, and the tread thickness is A (mm), the following formula (1) is satisfied. (d×D) / (DSI×30℃tanδ×A)≧0.7 (1)

[0010] In the above, the dimensional stability index DSI (%) is the sum of the intermediate elongation E (%) under a 2.0 cN / dtex load measured in accordance with JIS L1017 and the dry heat shrinkage rate HS (%) under a temperature of 180°C (E + HS). It can be considered an indicator of how easily deformation occurs under tensile stress load and heating, and codes with a large dimensional stability index DSI are considered to be easily deformable.

[0011] These features are thought to improve tire durability during high-speed driving.

[0012] 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.

[0013] (1) Use of sustainable polyester cord In the tire according to the present invention, sustainable polyester cord is used for the band cord.

[0014] In this invention, sustainable polyester cord refers to polyester cord manufactured using various recycling methods such as mechanical recycling and chemical recycling (recycled polyester cord), or biomass-derived polyester cord (biomass polyester cord). By using sustainable polyester cord, it is possible to reduce the environmental impact.

[0015] However, sustainable polyester cords have a high dimensional stability index, as will be discussed later, and a low modulus within the tire. Therefore, if sustainable polyester cords are used as band cords, the band's role as a belt reinforcement layer, i.e., its effect of suppressing belt vibration during driving, may not be fully realized, raising concerns about a deterioration in tire durability at high speeds.

[0016] (2) Control of the parameter ((d×D) / (DSI×30℃tanδ×A)) Therefore, in the present invention, when the cord diameter of the band cord is d (mm), the number of cords (ends) present in the direction perpendicular to the longitudinal direction at 5 cm is D (cords / 5 cm), the dimensional stability index is DSI (%), the loss tangent measured under the conditions of a tread temperature of 30°C, initial strain of 5%, dynamic strain of 1%, frequency of 10 Hz, deformation mode: tensile is 30°C tanδ, and the thickness of the tread is A (mm), the following formula (1) is satisfied. (d×D) / (DSI×30℃tanδ×A)≧0.7 (1)

[0017] In other words, by appropriately controlling the parameters related to the sustainable polyester cord ((d×D) / DSI) and the parameters related to the tread (30℃tanδ×A), it is believed that the durability of the tire during high-speed driving can be improved.

[0018] (a) Control by ((d×D) / DSI) By using a sustainable polyester cord with a high ratio of the product of cord diameter d and end length D (d×D) to the dimensional stability index DSI ((d×D) / DSI), the band's effect in suppressing belt vibrations is enhanced, which is expected to improve tire durability at high speeds.

[0019] By increasing (d×D), that is, by arranging cords with a large cord diameter at large ends to form a band, the rigidity of the band is increased, which can suppress belt vibration. On the other hand, as mentioned above, cords with a large DSI are easily deformed, so by using sustainable polyester cords with a small DSI, deformation of the band can be suppressed, and thus belt vibration can be suppressed.

[0020] Therefore, by increasing (d×D) while decreasing DSI, and controlling ((d×D) / DSI) to a large value, it is thought that belt vibration can be sufficiently suppressed, thereby improving tire durability during high-speed driving.

[0021] (b) Control by (30℃ tanδ × A) The loss tangent is a viscoelastic parameter that indicates energy absorption performance. A larger value means that energy is absorbed and converted into heat, causing the tire to overheat, reducing the rigidity of the band, and making the belt more prone to vibration. On the other hand, as the tread thickness increases, it becomes more susceptible to deformation.

[0022] Therefore, by reducing 30°C tanδ and A, and controlling (30°C tanδ × A) to a small value, it is believed that belt vibration and tread deformation can be sufficiently suppressed, thereby improving tire durability during high-speed driving.

[0023] Furthermore, by controlling ((d×D) / DSI) to a large value and (30℃tanδ×A) to a small value, thereby controlling the value of ((d×D) / (DSI×30℃tanδ×A)) to a large value, these effects work together to improve tire durability at high speeds, even when using sustainable polyester cord as a band cord.

[0024] [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.

[0025] 1. Band chord (1)Material As mentioned above, sustainable polyester cord is used as the band cord. As the sustainable polyester cord, a cord made by twisting one or more yarns containing sustainable polyester fibers can be used. For example, it is preferable to use a single-ply cord made by twisting one yarn containing sustainable polyester fibers, or a double-ply cord made by twisting two yarns.

[0026] Furthermore, sustainable polyester cord may be formed by twisting yarn composed solely of sustainable polyester fiber filaments, or by twisting yarn composed of a mixture of sustainable polyester fiber filaments and filaments of other fibers (such as polyester fibers other than sustainable polyester fibers, or polyamide fibers).

[0027] Among sustainable polyester fibers, the use of sustainable polyethylene terephthalate (PET) fiber is preferred. Among sustainable polyester fibers with a low modulus, sustainable PET fiber is preferred as a band cord because it is a highly rigid material. Specifically, as mentioned above, sustainable polyester fibers can include polyester fibers (recycled polyester fibers) produced using various recycling methods, such as sustainable polyester fibers (mechanically recycled polyester fibers) manufactured using a mechanical recycling method, and bio-derived polyester fibers (biomass polyester fibers). Recycled polyester fibers may also be recycled PET fibers (recycled PET fibers) produced by collecting and recycling plastic waste such as used PET bottles. As mentioned above, using such recycled polyester fibers or biomass polyester fibers is preferable from the viewpoint of environmental protection.

[0028] (2) Twist coefficient The twist coefficient of the sustainable polyester cord is preferably greater than 120, more preferably greater than 150, even more preferably greater than 200, and particularly preferably 250 or more. This increases the rigidity of the band and enhances the effect of suppressing belt vibration, which is thought to improve tire durability at high speeds. The upper limit is preferably 300 or less, more preferably less than 280, and even more preferably less than 260.

[0029] In the present invention, the value of the twist coefficient is a value defined by the following formula, based on the total fineness (dtex) of the sustainable polyester fiber and the number of twists per 10 cm of length in the sustainable polyester cord (twists / 10 cm). Twist coefficient = (Number of twists × 10) / [Square root of (10000 / total fineness)]

[0030] Here, the total fineness of the sustainable polyester cord is preferably greater than 1500 dtex, more preferably greater than 2000 dtex, and even more preferably greater than 2500 dtex. This increases the rigidity of the band and enhances the effect of suppressing belt vibration, which is thought to further improve the durability of the tire at high speeds. As an upper limit, it is preferably less than 4000 dtex, more preferably less than 3500 dtex, and even more preferably less than 3000 dtex.

[0031] In sustainable polyester cords, the total fineness is the sum of the fineness of each yarn, including the polyester fibers that make up the cord. For cords made from a single yarn, the total fineness is equivalent to the fineness of that single yarn, and for cords made from multiple yarns, it is equivalent to the sum of the fineness of the multiple yarns.

[0032] Furthermore, the number of twists per 10 cm of the sustainable polyester cord is preferably more than 25 twists / 10 cm, more preferably more than 30 twists / 10 cm, and even more preferably more than 40 twists / 10 cm. This increases the rigidity of the band and enhances the effect of suppressing belt vibration, which is thought to improve tire durability at high speeds. The upper limit is preferably less than 70 twists / 10 cm, more preferably less than 60 twists / 10 cm, and even more preferably less than 55 twists / 10 cm.

[0033] (3) Isophthalic acid content When sustainable polyester cord is made from recycled polyester cord, such as PET fibers or PET bottles, isophthalic acid may be present as an impurity, potentially leading to instability in the quality of the sustainable polyester cord. Therefore, the isophthalic acid content in sustainable polyester cord is preferably less than 0.1 mol%, which ensures stable quality. A content of 0.0 mol% (no isophthalic acid) is particularly preferable. The isophthalic acid content of sustainable polyester cord can be measured, for example, by high-performance liquid chromatography (HPLC).

[0034] (4) Cord diameter d The cord diameter d of the sustainable polyester cord is preferably greater than 0.40 mm, more preferably greater than 0.45 mm, and even more preferably greater than 0.50 mm. This increases the rigidity of the band and enhances the effect of suppressing belt vibration, which is thought to improve tire durability at high speeds. There is no particular upper limit, but it is preferably less than 0.80 mm, more preferably less than 0.75 mm, and even more preferably less than 0.70 mm.

[0035] The "cord diameter" can be measured in accordance with the method specified in JIS L1017:2002 "Test Method for Chemical Fiber Tire Cords". If the circumscribed circle of the cross-section perpendicular to the direction of cord extension is a perfect circle, it refers to the diameter. If it is an ellipse or similar, it refers to the equivalent diameter of the circle (the diameter of the circle assuming a perfect circle with the same cross-sectional area).

[0036] (5) Strength S (Tensile strength) The strength S (cN / dtex) of the sustainable polyester cord is preferably greater than 5.0 cN / dtex, more preferably greater than 5.5 cN / dtex, and even more preferably 6.0 cN / dtex or higher. This increases the rigidity of the band and enhances the effect of suppressing belt vibration, which is thought to improve tire durability at high speeds. There is no particular upper limit, but it is preferably less than 9.0 cN / dtex, more preferably less than 8.0 cN / dtex, and even more preferably less than 7.0 cN / dtex.

[0037] The strength S mentioned above can be measured in accordance with the method specified in JIS L1017:2002 "Test Method for Chemical Fiber Tire Cords".

[0038] (6) Ends D The end count D (threads / 5cm) of the sustainable polyester cord is preferably greater than 30 threads / 5cm, more preferably greater than 40 threads / 5cm, and even more preferably greater than 45 threads / 5cm. Increasing the end count D increases the rigidity of the band and enhances the effect of suppressing belt vibration, which is thought to improve tire durability at high speeds. There is no particular upper limit, but it is preferably less than 70 threads / 5cm, more preferably less than 60 threads / 5cm, and even more preferably less than 55 threads / 5cm.

[0039] Furthermore, the above-mentioned Ends D can be measured in accordance with the method specified in JIS L1017:2002 "Test Method for Chemical Fiber Tire Cords".

[0040] (7) The product of strength S and end D (S × D) The product of the strength S (cN / dtex) and the end count D (strands / 5cm) of the sustainable polyester cord (S × D) is preferably greater than 270, more preferably greater than 290, and even more preferably 310 or higher. This increases the rigidity of the band and enhances the effect of suppressing belt vibration, which is thought to improve tire durability at high speeds. There is no particular upper limit, but it is preferably less than 350, more preferably less than 340, and even more preferably less than 330.

[0041] (8)(L×D / E) Between the intermediate elongation E (%) at the specified load L (cN / dtex) of the sustainable polyester cord and the aforementioned ends D (strands / 5cm), (L × D / E) is preferably 15 or more, more preferably 20 or more, and even more preferably 23 or more. Increasing (L × D / E) increases the rigidity of the band, makes the band less prone to deformation, and enhances the effect of suppressing belt vibration, which is thought to improve tire durability at high speeds. The upper limit is preferably 45 or less, more preferably 40 or less, and even more preferably 37 or less.

[0042] (9) Dimensional Stability Index DSI The dimensional stability index (DSI) of the sustainable polyester cord is preferably less than 11.5%, more preferably less than 11.0%, and even more preferably less than 10.5%. This makes the band less prone to deformation and enhances the effect of suppressing belt vibration, which is thought to improve tire durability at high speeds. The lower limit is not particularly limited, but is preferably greater than 5.0%, more preferably greater than 5.5%, and even more preferably greater than 6.0%.

[0043] As mentioned above, the dimensional stability index DSI is the sum of the intermediate elongation E under a 2.0 cN / dtex load and the dry heat shrinkage HS under a temperature of 180°C, measured in accordance with JIS L1017.

[0044] Here, the intermediate elongation E of the sustainable polyester cord is preferably less than 7.0%, more preferably less than 6.0%, and even more preferably less than 5.0%. This makes the band less prone to deformation and increases the effect of suppressing belt vibration, which is thought to improve tire durability at high speeds. As a lower limit, it is preferably greater than 2.0%, more preferably greater than 2.5%, and even more preferably greater than 3.0%.

[0045] Furthermore, the dry heat shrinkage rate HS of the sustainable polyester cord is preferably less than 8.0%, more preferably less than 7.0%, and even more preferably less than 6.5%. This makes the band less prone to deformation and increases the effect of suppressing belt vibration, which is thought to improve tire durability at high speeds. The lower limit is preferably greater than 2.0%, more preferably greater than 3.0%, and even more preferably greater than 3.5%.

[0046] (10) Elongation at break The elongation at break of the sustainable polyester cord is preferably greater than 5%, more preferably greater than 10%, and even more preferably greater than 15%. A cord with a high elongation at break has a high modulus, and the band is more effective at suppressing belt vibration, which is thought to improve tire durability at high speeds. There is no particular upper limit, but it is preferably less than 20%, and more preferably less than 18%.

[0047] The above-mentioned elongation at break can be measured in accordance with the method specified in JIS L1017:2002 "Test Method for Chemical Fiber Tire Cords".

[0048] (11) Moisture and heat resistance strength retention rate The moisture- and heat-resistant strength retention rate of the sustainable polyester cord is preferably 80% or higher, more preferably over 85%, and even more preferably over 90%. This ensures that the band maintains high rigidity even under high-humidity and high-temperature conditions, and also maintains the effect of suppressing belt vibration, thereby improving tire durability during high-speed driving.

[0049] The above-mentioned moisture-heat resistance strength retention rate can be determined by calculating the ratio of the strength after treatment with saturated water vapor at 135°C for 48 hours (moist heat treatment) to the strength before treatment.

[0050] (12) Band formation A sustainable polyester cord can be treated with an adhesive and then bonded to a predetermined rubber band composition to form a band. Examples of adhesives that can be used for bonding include epoxy compounds such as EX-313 (glycerin polyglycidyl ether, manufactured by Nagase ChemteX Corporation) and RFL (resorcinol-formaldehyde latex).

[0051] 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.

[0052] 2. Tread (1) Loss tangent 30℃tanδ The tread's 30°C tanδ is preferably less than 0.35, more preferably less than 0.33, and even more preferably less than 0.31. As mentioned above, a tread with a small 30°C tanδ is thought to improve tire durability at high speeds because heat generation is suppressed, the decrease in band rigidity due to temperature rise is suppressed, and the effect of suppressing belt vibration is maintained. The lower limit is preferably greater than 0.20, and more preferably greater than 0.23.

[0053] Furthermore, in the above, the loss tangent 30°C tanδ can be measured using a dynamic viscoelasticity measuring device (for example, the Iplexer series (registered trademark) manufactured by GABO Corporation) on a test specimen measuring 20 mm in length, 4 mm in width, and 1 mm in thickness, which is cut from the tire tread so that the tire circumference is the longer side and the tire radius is the thickness direction.

[0054] Furthermore, the tread loss tangent 30°C tanδ can be appropriately adjusted in the rubber composition constituting the tread by adjusting, for example, the amount of styrene in the rubber component (polymer), the amount of fillers such as silica and carbon black, the content of softening agents, and the content of resin components.

[0055] (2) Thickness A Furthermore, the tread thickness A is preferably less than 20 mm, more preferably less than 15 mm, and even more preferably less than 12 mm. As a lower limit, it is preferably greater than 6 mm, more preferably greater than 8 mm, and even more preferably greater than 10 mm. This is thought to sufficiently suppress tread deformation and improve tire durability during high-speed driving.

[0056] In the above description, the tread is explained as a single layer consisting only of the contact surface layer (cap rubber layer). However, it may also consist of two layers, with a base rubber layer inside the cap rubber layer, or it may have three layers, or even four or more layers. In this case, the tread is preferably the cap rubber layer, which is the outermost layer on the contact surface side, and it is preferable that it satisfies the above parameters related to the tread, such as a loss tangent of 30°C tanδ.

[0057] In this case, the thickness of the cap rubber layer, which is the outermost layer of the entire tread composed of two or more layers, is preferably 10% or more, more preferably 30% or more, even more preferably 50% or more, and particularly preferably 70% or more.

[0058] Here, "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, 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 standard rim width.

[0059] 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.

[0060] 3. Parameter ((d × D) / (DSI × 30°C tanδ × A)) As described above, the tire according to the present invention controls ((d×D) / (DSI×30℃tanδ×A)) to 0.7 or higher, but it is more preferable if it is greater than 0.8, even more preferable if it is greater than 0.9, and even more preferable if it is greater than 1.0. This is thought to improve the durability of the tire at high speeds because the effect of the band in suppressing belt vibrations is greater. There is no particular upper limit, but it is preferable if it is less than 1.2, and even more preferable if it is less than 1.1.

[0061] [3] Embodiment The present invention will be described in detail below based on embodiments.

[0062] 1. Tire according to this embodiment Figure 1 is a schematic cross-sectional view illustrating a tire according to this embodiment. In Figure 1, 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 1, 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 1 shows 1 / 4 of the entire tire.

[0063] As shown in Figure 1, 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.

[0064] With this configuration, and as described above, using sustainable polyester cord as the band cord, and appropriately controlling parameters such as the cord diameter d of the band cord, the durability of the tire during high-speed driving can be improved by satisfying equation (1).

[0065] 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 components, and antioxidants.

[0066] (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.

[0067] (i) SBR The weight-average molecular weight of SBR is, for example, more than 100,000 and less than 2,000,000. The styrene content in SBR is preferably 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 40% by mass, more preferably less than 35% by mass, and even more preferably less than 30% by mass.

[0068] The glass transition temperature (Tg) of SBR is preferably -40°C or lower, more preferably -50°C or lower, even more preferably -60°C or lower, and particularly preferably -70°C or lower. On the other hand, there is no particular lower limit, but for example, it is preferably -90°C or higher.

[0069] The glass transition temperature (Tg) of SBR described above can be determined from the temperature distribution curve of tanδ measured using a viscoelasticity measuring device such as the "Iplexer®" series manufactured by GABO. Specifically, the temperature distribution curve of tanδ is measured under conditions of a frequency of 10 Hz, an initial strain of 10%, an amplitude of ±0.5%, and a heating rate of 2°C / min. The temperature corresponding to the largest tanδ value in the range of -100°C to 40°C of the measured temperature distribution curve is defined as the glass transition temperature (Tg).

[0070] Furthermore, if there are two or more points with the largest tanδ value within the range of -100°C to 40°C, the point with the lowest temperature is defined as the glass transition temperature (Tg). For example, if the tanδ peak is within the range of -100°C to 40°C, then according to the above definition, that peak temperature is the glass transition temperature (Tg). Also, for example, if the tanδ peak is in the region below -100°C, and a temperature distribution curve is obtained in which tanδ gradually decreases with increasing temperature within the range of -100°C to 40°C, then according to the above definition, the glass transition temperature (Tg) is -100°C.

[0071] The vinyl content (amount of 1,2-bonded butadiene units) of SBR is preferably 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 JEOL Ltd.'s JNM-ECA series.

[0072] 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.

[0073] 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.

[0074] Examples of the above-mentioned functional groups include amino groups, amide groups, silyl groups, alkoxysilyl groups, isocyanate groups, imino groups, imidazole groups, urea groups, ether groups, carbonyl groups, oxycarbonyl groups, mercapto groups, sulfide groups, disulfide groups, sulfonyl groups, sulfinyl groups, thiocarbonyl groups, ammonium groups, imide groups, hydrazo groups, azo groups, diazo groups, carboxyl groups, nitrile groups, pyridyl groups, alkoxy groups, hydroxyl groups, oxy groups, epoxy groups, and the like. These functional groups may also have substituents.

[0075] Furthermore, as modified SBR, for example, SBR modified with a compound (modifying agent) represented by the following formula can be used.

[0076] [ka]

[0077] Note that in the formula, R 1 , R 2 and R 3 R 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 R5 They may combine to form a ring structure together with a nitrogen atom. n represents an integer.

[0078] As the modified SBR modified by the compound (modifying agent) represented by the above formula, SBR obtained by modifying the polymerization terminal (active terminal) of solution-polymerized styrene-butadiene rubber (S-SBR) with the compound represented by the above formula (modified SBR described in JP-A-2010-111753, etc.) can be used.

[0079] R 1 , R 2 and R 3 An alkoxy group is preferable as (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms). R 4 and R 5 An alkyl group (preferably an alkyl group having 1 to 3 carbon atoms) is preferable. n is preferably 1 to 5, more preferably 2 to 4, and still more preferably 3. Further, when R 4 and R[[ID=2二十二]] 5 combine to form a ring structure together with a nitrogen atom, it is preferably a 4- to 8-membered ring. Note that the alkoxy group includes a cycloalkoxy group (such as a cyclohexyloxy group) and an aryloxy group (such as a phenoxy group and a benzyloxy group).

[0080] Specific examples of the above modifying agent include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, 3-diethylaminopropyltriethoxysilane, etc. These may be used alone or in combination of two or more.

[0081] 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.

[0082] 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.

[0083] The SBR content in 100 parts by mass of rubber component is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and even more preferably 30 parts by mass or more. As an upper limit, for example, it is preferably 70 parts by mass or less, more preferably 65 parts by mass or less, and even more preferably 60 parts by mass or less.

[0084] (b) Isoprene rubber Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR, but NR is preferred due to its superior strength.

[0085] For NR, common types used in the tire industry can be used, such as SVR-L, SIR20, RSS#3, and TSR20. 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. Modified NRs include deproteinized natural rubber (DPNR) and high-purity natural rubber (UPNR). Modified NRs include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Modified IRs include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used individually or in combination of two or more types.

[0086] The isoprene-based rubber content in 100 parts by mass of rubber components is preferably 5 parts by mass or more, and more preferably 10 parts by mass or more. As an upper limit, for example, it is preferably 70 parts by mass or less, and more preferably 60 parts by mass or less.

[0087] (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.

[0088] 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.

[0089] [ka]

[0090] Note that in the formula, R 1 , R 2and R 3 R 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.

[0091] 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.

[0092] 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).

[0093] 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.

[0094] 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.

[0095] For example, BR products from companies such as Ube Industries, Ltd., ENEOS Material Corporation, Asahi Kasei Corporation, and Nippon Zeon Corporation can be used.

[0096] The BR content in 100 parts by mass of rubber component is preferably 5 parts by mass or more, and more preferably 10 parts by mass or more. On the other hand, it is preferably 50 parts by mass or less, and more preferably 40 parts by mass or less.

[0097] (ii) Other rubber components The rubber composition may also include, as necessary, other rubber components, such as nitrile rubber (NBR) or other rubbers (polymers) commonly used in tire manufacturing.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] Whether the raw materials for a polymer are biomass-derived can be determined by measuring pMC (percent Modern Carbon) in accordance with ASTMD6866-10.

[0104] 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.

[0105] 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.

[0106] 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).

[0107] 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.

[0108] 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.

[0109] 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.

[0110] (b) Compounding materials other than rubber components (i) Filler The 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.

[0111] Regarding the amount of filler to be blended, it is preferable that the amount of silica blended is more than 75 parts by mass per 100 parts by mass of rubber component, but the total amount blended with other fillers is preferably 80 parts by mass or more, and more preferably 90 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 150 parts by mass or less, and more preferably 100 parts by mass or less.

[0112] (i) Silica Because silica has OH groups on its surface, incorporating silica into a rubber composition allows hydrogen bonds to form between silica surfaces and also interacts with the rubber components. Therefore, during driving, forces are easily generated and transmitted within the rubber, making it easier to transmit forces generated during turns and ensuring excellent handling stability. Furthermore, the OH groups on the surface can capture ozone, improving ozone resistance and thus enhancing tire durability.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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.).

[0119] Amorphous silica extracted from rice husks can be commercially available from companies such as Wilmar.

[0120] 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.

[0121] The silica content per 100 parts by mass of rubber component is preferably more than 75 parts by mass, more preferably 80 parts by mass or more, and even more preferably 90 parts by mass or more. Increasing the silica content can reduce the 30°C tanδ of the rubber composition. As an upper limit, for example, it is preferably 150 parts by mass or less, and more preferably 100 parts by mass or less.

[0122] (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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] (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.

[0127] 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.

[0128] 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.

[0129] 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.

[0130] 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.

[0131] 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.

[0132] 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.

[0133] 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.

[0134] (iv) Other fillers In addition to the carbon black and silica 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.

[0135] (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 kneading. Here, the softening agent component refers to a material (plasticizer component) that imparts plasticity to the rubber component, and is a concept that includes both softening agent components that are liquid at 25°C and softening agent components that are solid at 25°C.

[0136] Examples of softening agent components include resin components, oils, liquid polymers (liquid rubber), and ester-based plasticizers. These softening agent components 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 softening agent components. Among these, softening agent components derived from biomass or recycled materials are preferred as sustainable softening agent components.

[0137] These softening agent components may be used individually or in combination of two or more. The content of the softening agent component per 100 parts by mass of rubber component is preferably 15 parts by mass or more, more preferably 20 parts by mass or more, and even more preferably 25 parts by mass or more. The upper limit is preferably, for example, 85 parts by mass or less, more preferably 80 parts by mass or less, and even more preferably 75 parts by mass or less. The content of the softening agent component also includes the amount of oil contained in rubber (oil-applied rubber), etc.

[0138] (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.

[0139] (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.

[0140] 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).

[0141] 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.

[0142] 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.

[0143] (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.

[0144] 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.

[0145] 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).

[0146] 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.

[0147] 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.

[0148] 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.

[0149] 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.

[0150] (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.

[0151] 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).

[0152] The farnesene polymer may be a farnesene homopolymer (farnesene homopolymer) or a farnesene-vinyl monomer copolymer (farnesene-vinyl monomer copolymer).

[0153] 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).

[0154] 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).

[0155] As for liquid rubber, products from companies such as Kuraray Co., Ltd. and Clay Valley Corporation can be used.

[0156] (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.

[0157] 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.

[0158] 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.

[0159] 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.

[0160] 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.

[0161] 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).

[0162] 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.

[0163] 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.

[0164] 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.

[0165] "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.

[0166] "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.

[0167] "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.

[0168] While there are no particular limitations on the acrylic resin used, for example, a solvent-free acrylic resin can be used.

[0169] 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.

[0170] 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.

[0171] 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.

[0172] 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.

[0173] 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.

[0174] (H) Wax The rubber composition may contain wax. The wax content is preferably 0.5 parts by mass or more, more preferably 1.0 part by mass or more, and even more preferably 1.5 parts by mass or more, per 100 parts by mass of the rubber component. The upper limit is preferably 20 parts by mass or less, more preferably 15 parts by mass or more, and even more preferably 10 parts by mass or less.

[0175] 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.

[0176] 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.

[0177] 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.

[0178] (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.

[0179] 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.

[0180] 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.

[0181] (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.

[0182] 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.

[0183] 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.

[0184] Commercially available processing aids include products from companies such as Kishida Chemical Co., Ltd., Ken-ei Pharmaceutical Co., Ltd., Structol, and Performance Additives.

[0185] 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.

[0186] (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.

[0187] 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.

[0188] (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.

[0189] (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.

[0190] 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.

[0191] 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.

[0192] 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.

[0193] 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.

[0194] 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.

[0195] (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.

[0196] 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.

[0197] (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.

[0198] Mixing can be carried out using known (closed) mixers such as Banbury mixers, kneaders, and open roll mixers.

[0199] 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.

[0200] 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.

[0201] The rubber composition obtained as described above can then be molded into a tread by extruding it into a predetermined shape.

[0202] 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.

[0203] 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, a belt as a component to tighten the carcass and increase the rigidity of the tread, and a band as a component to reinforce the belt are wound around a molding drum, both ends of the carcass are fixed to both side edges, and a bead 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 section, thereby producing an unvulcanized tire.

[0204] 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.

[0205] As mentioned earlier, the resulting tire, by satisfying equation (1) above, benefits from the combined effects of the properties of the sustainable polyester cord and the properly formed tread, thereby improving tire durability at high speeds.

[0206] 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]

[0207] The following examples (implementations) are considered preferable for implementation, but the scope of the present invention is not limited to these examples.

[0208] We examined a tire (tire size: 195 / 65R15) consisting of a tread molded from the various compound materials listed below, as well as tire components such as bands and belts. The results calculated based on the evaluation method described later regarding tire durability during high-speed driving are shown at the bottom of Table 2.

[0209] 1. Preparation of rubber composition A rubber composition for the tread is prepared using the following compounding materials.

[0210] (1) Compounding materials (a) Rubber component (i) NR: TSR20 (b) SBR: Modified S-SBR obtained by the method shown below (manufacturing example) (Styrene content: 5% by mass, vinyl content: 30% by mass, glass transition temperature: -72°C) (H) BR: Ube Pole BR150B (High-Sys BR) manufactured by Ube Industries, Ltd. (Cis content 97% by mass, trans content 2% by mass, vinyl content 1% by mass)

[0211] (Manufacturing example) The above SBR is prepared according to the following procedure. First, two autoclaves with a volume of 10 L each, an inlet at the bottom and an outlet at the top, equipped with a stirrer and a jacket, are connected in series as reactors, and butadiene, styrene, and cyclohexane are mixed in predetermined ratios. This mixed solution is passed through a dehydration column packed with activated alumina, and after mixing with n-butyllithium in a static mixer to remove impurities, it is continuously supplied from the bottom of the first reactor. Furthermore, 2,2-bis(2-oxolanil)propane as a polar substance and n-butyllithium as a polymerization initiator are continuously supplied from the bottom of the first reactor at predetermined rates, while maintaining the reactor temperature at 95°C. The polymer solution is continuously withdrawn from the top of the reactor and supplied to the second reactor. The temperature of the second reactor is maintained at 95°C, and a mixture of tetraglycidyl-1,3-bisaminomethylcyclohexane (monomer) and the oligomer component is continuously added at a predetermined rate as a 1000-fold dilution of cyclohexane to carry out the modification reaction. This polymer solution is continuously withdrawn from the reactor, and an antioxidant is continuously added using a static mixer. After removing the solvent, the target modified diene polymer (SBR) is obtained.

[0212] (b) Compounding materials other than rubber components (i) Carbon black: Dia Black N220 manufactured by Mitsubishi Chemical Corporation (N2SA:115m 2 / g) (b) Silica: UltraSil VN3 manufactured by Evonik Industries (N2SA:175m 2 / g, average primary particle diameter: 17nm) (h) Silane coupling agent: Si266 manufactured by Evonik Industries (Bis(3-triethoxysilylpropyl) disulfide) (ii) Resin: SYLVATRAXX4401 manufactured by Kraton (α-methylstyrene resin) (H) Oil: Diana Process NH-70S manufactured by Idemitsu Kosan Co., Ltd. (Aromatic process oils) (H) Wax: REPSOL LUBRICANTES Y ESPECIALIDADES SA REDEZON 7216-BS (T) Anti-aging agent: ANTAGE 6C manufactured by Kawaguchi Chemical Industry Co., Ltd. (N-(1,3-dimethylbutyl)-N'phenyl-p-phenylenediamine) (Chi) Stearic acid: NOF Corporation's bead stearic acid "Tsubaki" (R) Zinc oxide: Two types of zinc oxide manufactured by Mitsui Mining & Smelting Co., Ltd. (Nu) Sulfur: Powdered sulfur manufactured by Tsurumi Chemical Industry Co., Ltd. (containing 5% oil) (L) Vulcanization accelerator-1: Noxellar CZ manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (N-cyclohexyl-2-benzothiadylsulfenamide (CBS)) (Wo) Vulcanization accelerator-2: Sokusil D manufactured by Sumitomo Chemical Co., Ltd. (N,N'-diphenylguanidine (DPG))

[0213] (2) Preparation of rubber composition for tread Based on the formulations A to C 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.

[0214] 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 C.

[0215] [Table 1]

[0216] 2. Molding of tire components (tread, band) (1) Tread molding Next, using the rubber composition obtained above, treads are molded at the thicknesses shown in Table 2.

[0217] (2) Forming the band In parallel, each band cord shown in Table 2 is topped with a predetermined rubber composition for bands to form each band. In Examples 1 to 5 and Comparative Example 3, a sustainable polyester cord, specifically mechanically recycled PET cord, is used as the band cord.

[0218] 3. Tire manufacturing Next, the treads and bands obtained above are bonded together with other tire components to form an unvulcanized tire, which is then press-vulcanized for 10 minutes under conditions of 170°C to produce the test tires for Examples 1 to 5 and Comparative Examples 1 to 3.

[0219] Next, rubber test pieces for viscoelasticity measurement were prepared by cutting out a piece from the tread of each test tire, with the tire circumference as the longer side, measuring 20 mm in length, 4 mm in width, and 1 mm in thickness. For each rubber test piece, the loss tangent tanδ was measured using the "Iplexer®" series manufactured by GABO Corporation, under the conditions of a temperature of 30°C, a frequency of 10 Hz, an initial strain of 5%, and a dynamic strain of 1%, with the deformation mode being tensile.

[0220] The thickness direction of the sample should be the tire radius direction. If the same compound is used in multiple examples, the average value measured from each test tire should be used.

[0221] 4. Performance evaluation (Evaluation of tire durability during high-speed driving) Each test tire is mounted on a rim (size = 16 x 6.5J), and the tire's durability under high-speed driving conditions is tested in accordance with the method specified in JIS D 4230:1998 "Automotive Tires".

[0222] Next, the results in Comparative Example 1 are set to 100 and indexed based on the following formula to evaluate the tire's durability at high speeds. A higher value indicates superior tire durability at high speeds. Tire durability evaluation at high speeds =[(Results of the test tire) / (Results of Comparative Example 1)]×100

[0223]

Table 2

[0224] 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.

[0225] The present invention (1) is a carcass, a belt provided on the outer side in the tire radial direction of the carcass, a band provided with 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 band cord is a sustainable polyester cord, when the cord diameter of the band cord is d (mm), the number of cords present in a 5 cm length in the direction perpendicular to the longitudinal direction is D (cords / 5 cm), the dimensional stability index is DSI (%), the temperature of the tread is 30°C, the initial strain is 5%, the dynamic strain is 1%, the frequency is 10 Hz, and the loss tangent measured under the conditions of the deformation mode: tension is 30°C tan δ, and the thickness of the tread is A (mm), the tire is characterized by satisfying the following formula (1). (d × D) / (DSI × 30°C tan δ × A) ≥ 0.7 (1)

[0226] The present invention (2) is characterized in that ((d × D) / (DSI × 30°C tan δ × A)) is greater than 0.8, and it is the tire according to the present invention (1).

[0227] The present invention (3) is characterized in that the sustainable polyester cord is a sustainable polyethylene terephthalate cord, and it is the tire according to the present invention (1).

[0228] The present invention (4) is, The tire is characterized in that the sustainable polyester cord is a two-ply cord, as described in (1) of the present invention.

[0229] The present invention (5) is, The tire is characterized in that the isophthalic acid content in the sustainable polyester cord is less than 0.1 mol%, and is any combination of any of the present invention (1) to (4).

[0230] The present invention (6) is, The tire is characterized in that the strength S(cN / dtex) of the sustainable polyester cord is 5.0 cN / dtex or more, and is any combination of the present invention (1) to (4).

[0231] The present invention (7) is, The tire is characterized in that the product (S × D) of the strength S (cN / dtex) of the sustainable polyester cord and the number of cords D (cords / 5cm) present in a direction perpendicular to the longitudinal direction of the sustainable polyester cord satisfies the following formula, and is any combination of any of the present invention (1) to (4). S × D ≥ 310

[0232] The present invention (8) is, The tire is characterized in that the following equation is satisfied between the intermediate elongation E (%) of the sustainable polyester cord at a specified load L (cN / dtex) and the number of cords D (cords / 5cm) present in a direction perpendicular to the longitudinal direction of the sustainable polyester cord at 5cm, and is a tire in any combination with any of the present invention (1) to (4). 23 ≤ L × D / E ≤ 37

[0233] The present invention (9) is, The tire is characterized in that the elongation at break of the sustainable polyester cord is 10% or more, and is any combination of the present invention (1) to (4).

[0234] The present invention (10) is, The tire is characterized in that the moisture-heat resistance strength retention rate of the sustainable polyester cord is 80% or more, and is any combination of any of the present invention (1) to (4).

[0235] The present invention (11) is, The tire is characterized in that the twist coefficient of the sustainable polyester cord is 250 or more and 300 or less, and is any combination of any of the present invention (1) to (4).

[0236] The present invention (12) is, The tire is characterized in that the total fineness of the sustainable polyester cord exceeds 1500 dtex, and is any combination of the present invention (1) to (4).

[0237] The present invention (13) is, The tire is characterized in that the number of twists per 10 cm of length in the sustainable polyester cord is more than 25 (twists / 10 cm), and is any combination of the present invention (1) to (4).

[0238] The present invention (14) is, The tire is characterized in that the cord diameter of the sustainable polyester cord is greater than 0.40 mm, and is any combination of the sustainable polyester cord with any of the present invention (1) to (4).

[0239] The present invention (15) is, The tire is characterized in that the number of cords D located 5 cm perpendicular to the longitudinal direction of the sustainable polyester cord is greater than 30 (cords / 5 cm), and is any combination of any of the present invention (1) to (4).

[0240] The present invention (16) is, The tire is characterized in that the dry heat shrinkage rate of the sustainable polyester cord, measured in accordance with JIS L1017 under a temperature of 180°C, is less than 8.0%, and is any combination of the present invention (1) to (4).

[0241] The present invention (17) is characterized in that the dimensional stability index DSI of the sustainable polyester cord is less than 11.5%, and it is a tire in any combination of any one of the present inventions (1) to (4).

[0242] The present invention (18) is characterized in that the 30°C tanδ of the tread is less than 0.35, and it is a tire in any combination of any one of the present inventions (1) to (4).

[0243] The present invention (19) is characterized in that the thickness A of the tread is less than 20 mm, and it is a tire in any combination of any one of the present inventions (1) to (4).

Explanation of Signs

[0244] 1 Tire 2 Tread 3 Sidewall 4 Chafer 5 Bead 6 Innerliner 7 Carcass 8 Belt 9 Filler 10 Band CL Equatorial plane of the tire

Claims

1. Carcass and, A belt 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 aforementioned band cord is a sustainable polyester cord. A tire characterized in that, when the cord diameter of the band cord is d (mm), the number of cords located 5 cm perpendicular to the longitudinal direction is D (cords / 5 cm), the dimensional stability index is DSI (%), the loss loss tangent measured under the conditions of a tread temperature of 30°C, initial strain of 5%, dynamic strain of 1%, frequency of 10 Hz, deformation mode: tensile is 30°C tanδ, and the thickness of the tread is A (mm), the tire satisfies the following formula (1). (d × D) / (DSI × 30°C tanδ × A) ≥ 0.7 (1)

2. The tire according to claim 1, characterized in that the above ((d × D) / (DSI × 30°C tanδ × A)) is greater than 0.

8.

3. The tire according to claim 1, characterized in that the sustainable polyester cord is a sustainable polyethylene terephthalate cord.

4. The tire according to claim 1, characterized in that the sustainable polyester cord is a two-ply cord.

5. The tire according to any one of claims 1 to 4, characterized in that the isophthalic acid content in the sustainable polyester cord is less than 0.1 mol%.

6. The tire according to any one of claims 1 to 4, characterized in that the strength S (cN / dtex) of the sustainable polyester cord is 5.0 cN / dtex or more.

7. The tire according to any one of claims 1 to 4, characterized in that the product (S × D) of the strength S (cN / dtex) of the sustainable polyester cord and the number of cords D (cords / 5cm) present in a direction perpendicular to the longitudinal direction of the sustainable polyester cord satisfies the following formula. S × D ≥ 310

8. The tire according to any one of claims 1 to 4, characterized in that the following formula is satisfied between the intermediate elongation E (%) of the sustainable polyester cord at a specified load L (cN / dtex) and the number of cords D (cords / 5cm) present in a direction perpendicular to the longitudinal direction of the sustainable polyester cord at 5cm. 23 ≤ L × D / E ≤ 37

9. The tire according to any one of claims 1 to 4, characterized in that the elongation at break of the sustainable polyester cord is 10% or more.

10. The tire according to any one of claims 1 to 4, characterized in that the moisture-heat resistance strength retention rate of the sustainable polyester cord is 80% or more.

11. The tire according to any one of claims 1 to 4, characterized in that the twist coefficient of the sustainable polyester cord is 250 or more and 300 or less.

12. The tire according to any one of claims 1 to 4, characterized in that the total fineness of the sustainable polyester cord is greater than 1500 dtex.

13. The tire according to any one of claims 1 to 4, characterized in that the number of twists per 10 cm of length in the sustainable polyester cord is more than 25 (twists / 10 cm).

14. The tire according to any one of claims 1 to 4, characterized in that the cord diameter of the sustainable polyester cord is greater than 0.40 mm.

15. The tire according to any one of claims 1 to 4, characterized in that the number of cords D located in a 5 cm direction perpendicular to the longitudinal direction of the sustainable polyester cord is greater than 30 (cords / 5 cm).

16. The tire according to any one of claims 1 to 4, characterized in that the dry heat shrinkage rate (%) of the sustainable polyester cord at a temperature of 180°C, as measured in accordance with JIS L1017, is less than 8.0%.

17. The tire according to any one of claims 1 to 4, characterized in that the dimensional stability index DSI of the sustainable polyester cord is less than 11.5%.

18. The tire according to any one of claims 1 to 4, characterized in that the 30°C tanδ of the tread is less than 0.

35.

19. The tire according to any one of claims 1 to 4, characterized in that the thickness A of the tread is less than 20 mm.

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