Tire

Abstract

The present invention aims to improve the block resistance. It is a tire characterized by having a tread portion along a circumferential main groove using: a rubber component of 100 parts by mass containing more than 60 parts by mass of styrene styrene butadiene rubber (SBR) having a styrene amount of 25% by mass or less, and more than 10 parts by mass of isoprene-based rubber, further containing more than 105 parts by mass of silica, more than 25 parts by mass of a resin component, a complex modulus at 0°C E * (MPa) measured at a temperature of 0°C, a frequency of 10 Hz, an initial strain of 5%, a dynamic strain rate of 1%, and a deformation mode of elongation, and each loss tangent measured at a temperature of 0°C, -20°C, -30°C, -40°C under conditions of a frequency of 10 Hz, an initial strain of 5%, a dynamic strain rate of 1%, and a deformation mode of elongation satisfy formula (1), and B1 and the depth D (mm) of the main groove satisfy formula (2). B1[={(-40°C tan δ) + (-30°C tan δ) + (-20°C tan δ)} × 0°C tan δ / 0°C E * ]>0.005 (1) D / B1<1000 (2).

Description

Technical Field

[0001] This invention relates to a tire. Background Technology

[0002] In recent years, various proposals have been put forward (e.g., Patent Documents 1-5) to address the need to improve the block resistance of tires installed on vehicles, but these are still not sufficient.

[0003] [Existing Technical Documents]

[0004] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-218481

[0006] [Patent Document 2] Japanese Patent Application Publication No. 2020-59769

[0007] [Patent Document 3] Japanese Patent Application Publication No. 2021-25006

[0008] [Patent Document 4] Japanese Patent Application Publication No. 2022-43616

[0009] [Patent Document 5] Japanese Patent Application Publication No. 2022-121896 Summary of the Invention

[0010] [The problem the invention aims to solve]

[0011] The objective of this invention is to further improve the tire's resistance to blockage.

[0012] [Methods for solving the problem]

[0013] This invention relates to a tire, characterized in that,

[0014] It has a tread section with main grooves along the circumference of the tire.

[0015] The tread portion is formed using a rubber composition.

[0016] The rubber composition, in 100 parts by weight of the rubber component, contains more than 60 parts by weight of styrene-butadiene rubber (SBR) with a styrene content of less than 25% by weight, and more than 10 parts by weight of isoprene-based rubber. Further, relative to 100 parts by weight of the rubber component, the rubber composition contains more than 105 parts by weight of silica and more than 25 parts by weight of resin component.

[0017] The complex elastic modulus of the tread area is 0°CE. *(MPa) and the loss tangents of the tread portion (0℃tanδ, -20℃tanδ, -30℃tanδ, -40℃tanδ) satisfy the following equation (1), and the complex elastic modulus E at 0℃ * The pressure (MPa) was measured at 0℃, 10Hz, initial strain 5%, dynamic strain rate 1%, and deformation mode: elongation. The loss tangents (0℃ tanδ, -20℃ tanδ, -30℃ tanδ, -40℃ tanδ) were measured at 10Hz, initial strain 5%, dynamic strain rate 1%, and deformation mode: elongation, at temperatures of 0℃, -20℃, -30℃, and -40℃.

[0018] The B1 shown in equation (1) and the depth D (mm) of the main trench satisfy the following equation (2).

[0019] B1[={(-40℃tanδ)+(-30℃tanδ)+(-20℃tanδ)}×0℃tanδ / 0℃E * ]>0.005 (1)

[0020] D / B1<1000 (2)

[0021] [Invention Effects]

[0022] According to the present invention, the tire's resistance to block shedding can be further improved. Detailed Implementation

[0023] [1] Features of the tires involved in this invention

[0024] The features of the tire involved in this invention will first be described.

[0025] 1. Overview

[0026] The tire of the present invention has a tread portion having a main groove along the circumferential direction of the tire. The tread portion is formed using a rubber composition containing, in 100 parts by weight of rubber components, more than 60 parts by weight of styrene-butadiene rubber (SBR) with a styrene content of 25% or less, and more than 10 parts by weight of isoprene-based rubber. Further, relative to 100 parts by weight of rubber components, the rubber composition contains more than 105 parts by weight of silica and more than 25 parts by weight of resin components. Furthermore, the tread portion has a complex elastic modulus of 0°C. * (MPa) and the loss tangents of each tread angle (0℃tanδ, -20℃tanδ, -30℃tanδ, -40℃tanδ) satisfy the following equation (1), wherein the complex elastic modulus of the tread at 0℃E *(MPa) was measured at a temperature of 0℃, a frequency of 10Hz, an initial strain of 5%, a dynamic strain rate of 1%, and a deformation mode of elongation. The loss tangents of the tread face (0℃tanδ, -20℃tanδ, -30℃tanδ, -40℃tanδ) were measured at a frequency of 10Hz, an initial strain of 5%, a dynamic strain rate of 1%, and a deformation mode of elongation at temperatures of 0℃, -20℃, -30℃, and -40℃. Furthermore, B1 as shown in the following formula (1) and the depth D (mm) of the main groove satisfy the following formula (2).

[0027] B1[={(-40℃tanδ)+(-30℃tanδ)+(-20℃tanδ)}×0℃tanδ / 0℃E * ]>0.005 (1)

[0028] D / B1<1000 (2)

[0029] By incorporating these features, as described below, it is possible to further improve the resistance to chipping.

[0030] 2. The principle underlying the performance effect in tires involved in this invention.

[0031] The principle underlying the aforementioned performance effects in the tires involved in this invention can be considered as follows.

[0032] (1) Contains low-styrene SBR

[0033] As described above, the tire tread of the present invention contains styrene-butadiene rubber (SBR) with a styrene content of more than 60 parts by mass and a styrene content of less than 25% by mass in 100 parts by mass of rubber composition.

[0034] Because SBRs with a low styrene content, specifically SBRs with a styrene content of less than 25% by mass (low-styrene SBRs), have a lower glass transition temperature (Tg), the Tg of the rubber component in the rubber composition can be reduced by forming the tread portion using a rubber composition containing more than 60 parts by mass of low-styrene SBR per 100 parts by mass of the rubber component. Furthermore, by compounding up to more than 60 parts by mass of low-styrene SBR, small styrene domains are formed in the rubber matrix, which improves the polymer's mobility, allowing it to move flexibly.

[0035] These results can be considered as making it less likely for cracks to occur as a cause of chipping, thus improving chipping resistance.

[0036] Furthermore, it can be argued that the small, flexibly moving styrene regions are more prone to heat generation through mutual friction, thus further promoting the movement of these small styrene regions and enabling improved resistance to chipping.

[0037] Furthermore, it can be considered that by blending low-styrene SBR to form small styrene regions, it is easy for them to interact with reinforcing fillers, thus fully exerting the reinforcing effect, thereby increasing the breaking energy and improving the resistance to spalling.

[0038] (2) Rubber containing isoprene

[0039] In this invention, in addition to the aforementioned low-styrene SBR, the tread portion also contains more than 10 parts by mass of isoprene rubber as a rubber component in 100 parts by mass of the rubber component.

[0040] It can be assumed that this can form a phase separation structure between SBR and isoprene rubber, with micro-layers of different hardness mixed in the rubber phase, which can suppress the transmission of impact and cracking from the tire surface and improve the resistance to chipping.

[0041] (3) Contains silicon dioxide

[0042] In this invention, the tread portion further contains a large amount of silica exceeding 105 parts by mass relative to 100 parts by mass of the rubber component. It can be considered that this large amount of silica, through the interaction between the flexibly moving micro-styrene regions and the silica, enables improved resistance to chipping.

[0043] In addition, by containing a large amount of silica, the tread can be hardened, thus improving wear resistance and enhancing anti-scraping performance.

[0044] (4) Contains resin components

[0045] In this invention, the tread portion contains, in addition to silica, a large amount of resin component, greater than 25 parts by mass per 100 parts by mass of rubber component. It can be considered that by containing such a large amount of resin component, the energy loss of the rubber composition increases, thereby improving wear resistance and enhancing anti-scraping performance.

[0046] (5) Control of B1

[0047] The loss tangent can be considered an indicator of energy absorption performance. The larger the value, the easier it is to generate sufficient energy loss in the rubber composition, suppress defects caused by rubber deformation, and improve the resistance to shavings.

[0048] On the other hand, the complex elastic modulus can be considered as an indicator of the rigidity of the rubber composition. The smaller the value, the softer the rubber becomes, thereby suppressing slippage with the road surface, improving wear resistance, and achieving improved resistance to rockfall.

[0049] Therefore, it can be considered that by appropriately controlling the balance between the loss tangent and the complex elastic modulus, the resistance to chipping can be improved.

[0050] Specifically, the complex elastic modulus of the tread area can be considered to be 0°CE. * The formula B1, derived from (MPa) and the tangents of the various loss angles of the tire tread (0℃tanδ, -20℃tanδ, -30℃tanδ, -40℃tanδ), is: B1 = [{(-40℃tanδ) + (-30℃tanδ) + (-20℃tanδ)} × 0℃tanδ / 0℃E * The complex elastic modulus E at 0°C is significantly related to the crack propagation rate. * The loss tangents (0℃ tanδ, -20℃ tanδ, -30℃ tanδ, -40℃ tanδ) of the tread surface were measured at 0℃, 10Hz, 5% initial strain, 1% dynamic strain rate, and elongation deformation mode. Therefore, by appropriately controlling B1 to be greater than 0.005, the anti-scraping performance can be improved.

[0051] Furthermore, the aforementioned complex elastic modulus and loss tangent can be measured using viscoelasticity measuring devices such as the "EPLEXOR (registered trademark)" manufactured by GABO Corporation.

[0052] Furthermore, the aforementioned loss tangent and complex modulus can be adjusted by the type and amount of reagents (especially rubber components, fillers, resin components, sulfur, and vulcanization accelerators) compounded in the rubber composition. For example, by increasing the SBR content, increasing the content of fillers or resin components, the loss tangent can be increased; by increasing the amount of fillers, increasing the amount of sulfur, or increasing the amount of vulcanization accelerators, the complex modulus can be increased.

[0053] (6) Relationship between the depth of the main trench and B1

[0054] Furthermore, in this invention, the ratio (D / B1) of the depth D (mm) of the main trench to B1 is controlled to be less than 1000. It can be considered that this makes it difficult for cracks, which are a cause of spalling, to occur, thus improving spalling resistance. That is, it can be considered that by appropriately controlling B1 as described above, spalling resistance can be improved, but in addition, by increasing the depth of the main trench, the overall spalling resistance can be further improved.

[0055] It can be considered that in this invention, by making the above-mentioned effects work synergistically, the overall performance of tire wear resistance and chipping resistance can be further improved.

[0056] [2] A more preferred embodiment of the tires involved in the present invention

[0057] The tires involved in this invention can achieve further and greater effects by employing the following methods.

[0058] 1. Low-styrene SBR

[0059] As described above, improved spalling resistance can be achieved by using low-styrene SBR with a styrene content of 25% by mass or less. Furthermore, with the reduction in styrene content, the glass transition temperature (Tg) also decreases further, thus enabling further improvement in spalling resistance.

[0060] That is, in this invention, the styrene content of the low-styrene SBR is more preferably 20% by mass or less, more preferably 15% by mass or less, and particularly preferably 10% by mass or less. On the other hand, as a lower limit, it is preferably 3% by mass or more, more preferably 5% by mass or more, and even more preferably 7% by mass or more.

[0061] Here, "SBR containing more than 60 parts by mass of styrene with a styrene content of less than 25% by mass in 100 parts by mass of rubber component" means that the amount of SBR in 100 parts by mass of rubber component is greater than 60 parts by mass, and the total amount of styrene in SBR is less than 25% by mass.

[0062] That is, when the rubber component contains a styrene-containing polymer (SBR), it means that the amount of styrene is 25% by mass or less; when the rubber component contains multiple styrene-containing polymers (SBR), it means that the amount of styrene, calculated by summing the product of the amount of styrene in each polymer (by mass) and the amount of that polymer mixed with 100 parts by mass of the rubber component (by mass), is 25% by mass or less.

[0063] More specifically, when 100 parts by mass of rubber composition contain SBR1 (X1 parts by mass) of styrene S1% and SBR2 (X2 parts by mass) of styrene S2%, it means that the amount of styrene calculated by the formula (S1×X1)+(S2×X2)} / (X1+X2) is 25% by mass or less.

[0064] Furthermore, the amount of styrene in the vulcanized rubber composition can be determined using solid-state nuclear magnetic resonance (SMR) or Fourier transform infrared spectrophotometry (FTIR), and can also be calculated. The same applies to the vinyl content of the SBR described below. These component amounts are related to the complex elastic modulus (E... *Since physical properties such as total styrene in rubber components differ, true values ​​exist that are independent of the measurement method. Therefore, it is preferable to use a measurement method with the highest possible accuracy. Furthermore, in the embodiments of this specification, the total styrene content in the rubber components can be calculated using the formulas described in this specification, or analyzed based on tires using methods such as Py-GC / MS.

[0065] Furthermore, the SBR content in 100 parts by weight of the rubber component is set to be greater than 60 parts by weight, more preferably greater than 65 parts by weight, and even more preferably greater than 70 parts by weight. As an upper limit, for example, it is preferably less than 90 parts by weight, more preferably less than 85 parts by weight, and even more preferably less than 80 parts by weight.

[0066] Furthermore, the glass transition temperature (Tg) of the low-styrene SBR is preferably below -25°C, more preferably below -40°C, even more preferably below -55°C, and particularly preferably below -70°C. On the other hand, as a lower limit, it is preferably above -90°C, more preferably above -85°C, and even more preferably above -80°C.

[0067] Furthermore, the glass transition temperature of SBR can be determined based on the temperature distribution curve of tanδ measured using a viscoelasticity measuring device such as the GABO "EPLEXOR" series. Specifically, the temperature distribution curve of tanδ is measured under the 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 maximum tanδ value in the range of -100 °C to 40 °C is set as the glass transition temperature (Tg).

[0068] Furthermore, if there are two or more points with the maximum tanδ value within the range of -100°C to 40°C, the point with the lowest temperature is set as the glass transition temperature (Tg). For example, in this invention, if the peak value of tanδ is within the range of -100°C to 40°C, then according to the above definition, this peak temperature is taken as the glass transition temperature (Tg). Furthermore, for example, if a temperature distribution curve is obtained where the peak value of tanδ is in a region less than -100°C and within the range of -100°C to 40°C, and tanδ gradually decreases with increasing temperature, then according to the above definition, the glass transition temperature (Tg) is -100°C.

[0069] 2. Isoprene-based rubbers

[0070] It can be considered that by including more than 10 parts by mass of isoprene-based rubber in 100 parts by mass of the rubber component, in addition to low-styrene SBR, as described above, improved spalling resistance can be achieved. More preferably, the content of isoprene-based rubber in 100 parts by mass of the rubber component is more than 15 parts by mass, and even more preferably more than 20 parts by mass. On the other hand, as an upper limit, it is preferably less than 30 parts by mass, and more preferably less than 25 parts by mass.

[0071] Specific isoprene-based rubbers include natural rubber (NR), modified natural rubber (modified NR), modified natural rubber (modified NR), and synthetic polyisoprene (isoprene rubber (IR), modified isoprene rubber (modified IR)), etc., but among these, NR with excellent strength is preferred. Furthermore, as NR, for example, materials commonly used in the tire industry such as SVR-L, SIR20, RSS#3, and TSR20 can be used.

[0072] 3. Silicon dioxide

[0073] By containing a large amount of silica, greater than 105 parts by mass relative to 100 parts by mass of the rubber component, as described above, improved resistance to spalling can be achieved. More preferably, it is greater than 120 parts by mass, and even more preferably, it is greater than 130 parts by mass. On the other hand, there is no particular upper limit, but it is preferably less than 180 parts by mass, more preferably less than 170 parts by mass, and even more preferably less than 160 parts by mass.

[0074] 4. Resin composition

[0075] It can be considered that by containing a large amount of resin component, greater than 25 parts by mass relative to 100 parts by mass of the rubber component, as described above, improved resistance to spalling can be achieved. More preferably, it is greater than 30 parts by mass. As an upper limit, there is no particular limitation, but it is preferably less than 40 parts by mass, and more preferably less than 35 parts by mass.

[0076] Specific resin components include, for example, rosin-based resins, styrene-based resins, coumarone-based resins, terpene-based resins, C5 resins, C9 resins, C5C9 resins, and acrylic resins, but C5 resins and C9 resins are more preferred among these, and dicyclopentadiene resin (DCPD resin) and AMS resin (α-methylstyrene resin) are particularly preferred. Dicyclopentadiene resin may also be hydrogenated.

[0077] 5. Control B1

[0078] It can be assumed that by appropriately controlling B1 = [{(-40℃tanδ) + (-30℃tanδ) + (-20℃tanδ)} × 0℃tanδ / 0℃E as described above... *A value greater than 0.005 can improve the resistance to chipping. More preferably, it is greater than 0.010, and even more preferably, it is greater than 0.015.

[0079] 6. Relationship between SBR quantity and flatness ratio

[0080] It can be argued that by using a large amount of SBR, cracking, which is the cause of slugging, is less likely to occur, and even with a low aspect ratio (the ratio of tire section height to section width), slugging resistance can be improved.

[0081] Specifically, it can be considered that if the SBR content in 100 parts by mass of the rubber component is C S The ratio of (parts by weight) to the tire's aspect ratio A (%) (C) S If / A) is greater than 1, then the resistance to block shedding can be improved.

[0082] C S / A is more preferably greater than 1.10, and even more preferably greater than 1.15. As an upper limit, for example, it is preferably less than 1.20, and more preferably less than 1.18.

[0083] 7. Relationship between silica content and negative profile ratio

[0084] Negative profile ratio refers to the ratio (%) of the total open area of ​​multiple grooves to the virtual contact area of ​​the tread that completely fills all multiple grooves (the total contact area of ​​the tire around its entire circumference when the tread with a camber angle of 0° is pressed against a plane under normal internal pressure and normal load conditions, with the tread completely filled with multiple grooves in a normal state). It can be considered that the smaller this ratio (lower negative profile ratio), the larger the contact area with the road surface, which can generate greater energy loss across the entire tread surface and improve the resistance to blockage.

[0085] On the other hand, it can be considered that even if silica contains a large amount of reinforcing filler, as mentioned above, it is possible to achieve improved resistance to chipping.

[0086] Therefore, it can be considered that by appropriately controlling the amount of silica C relative to 100 parts by mass of the rubber component... SI The ratio of (parts by weight) to the negative profile ratio N (%) of the tire (C) SI / N), which can improve resistance to block shedding. Specifically, the ratio (C SI The ratio ( / N) is preferably greater than 1, more preferably greater than 1.3, and even more preferably greater than 1.5. As an upper limit, for example, it is preferably less than 1.9, more preferably less than 1.7.

[0087] Furthermore, the aforementioned negative profile ratio can be determined based on the grounding shape under normal rim, normal internal pressure, and normal load conditions.

[0088] Specifically, the ground contact shape can be obtained by assembling a tire onto a standard rim, applying standard internal pressure, allowing it to stand at 25°C for 24 hours, then applying ink to the tire tread surface, subjecting the tire to a standard load, and pressing it onto a cardboard (camber angle 0°), allowing the ink to transfer onto the cardboard. The tire is then rotated 72° circumferentially, resulting in 5 transfer points. That is, 5 ground contact shapes are obtained. For the 5 ground contact shapes, the average of the maximum axial length of the tire is set as L, and the average of the length perpendicular to the axial direction is set as W. The negative profile ratio (%) is calculated as [1 - {Average area of ​​the 5 ground contact shapes (ink portions) transferred to the cardboard / L × W)} × 100 (%). Here, the average length and area are a simple average of the 5 values, where L × W represents the area of ​​the virtual surface obtained by connecting the blank areas of the main groove and transverse groove when the ground contact shape is obtained.

[0089] Here, "normal condition" means: the tire is assembled on a normal rim and filled with normal internal pressure, and is unloaded.

[0090] "Standard rim" refers to the rim specified for each tire within a standard system that includes the standards upon which the tire is based. For example, it refers to the standard rim with applicable dimensions listed in the JATMA (Japan Automobile Tire Association) Yearbook, the "Measuring Rim" listed in the ETRTO (European Tyre and Rim Technical Organization) Standards Manual, and the "Design Rim" listed in the TRA (Tire and Rim Association, Inc.) Yearbook. These should be referenced in the order of JATMA, ETRTO, and TRA, and if applicable dimensions are available, their standards should be followed. Furthermore, for tires not specified in the aforementioned standards, it refers to the rim with the smallest rim width among the smallest rim diameters that can be assembled and maintain internal pressure (i.e., no air leakage between the rim and tire).

[0091] Furthermore, "standard internal pressure" refers to the air pressure specified for each tire within the standard system upon which the tire is based. This includes the maximum value recorded in JATMA's "Maximum Air Pressure," ETRTO's "Inflation Pressure," and TRA's table "Tire Load Limits at Various Cold Inflation Pressures," referenced in the order of JATMA, ETRTO, and TRA. If an applicable size is specified, that standard should be followed. For tires not specified in the aforementioned standards, it refers to the standard internal pressure (of which 250 kPa or higher) for other tire sizes (those specified in the standards) using the aforementioned standard rim as the standard rim. Additionally, when multiple standard internal pressures of 250 kPa or higher are recorded, the minimum value is used.

[0092] Furthermore, "standard load" refers to the load specified for each tire within a standard system that includes the standard on which the tire is based. It refers to the maximum mass allowed to be applied to the tire, specifically the maximum value recorded in JATMA's "Maximum Load Capacity," ETRTO's "Load Capacity," and TRA's "Tire Load Limits at Various Cold Inflation Pressures." Similar to the cases of "standard rim" and "standard internal pressure," it is referenced in the order of JATMA, ETRTO, and TRA, following the applicable standard if applicable dimensions are available. For tires not specified in the standard, the standard load W is calculated using the following methods. L .

[0093] V = {(Dt / 2)} 2 -(Dt / 2-Ht) 2}×π×Wt

[0094] W L =0.000011×V+175

[0095] W L Standard load (kg)

[0096] V: Virtual volume of the tire (mm) 3 )

[0097] Dt: Tire outer diameter Dt (mm)

[0098] Ht: Tire section height (mm)

[0099] Wt: Tire cross-sectional width (mm)

[0100] 8. Particle size of silica

[0101] Considering factors such as ease of friction with the polymer, the particle size (average primary particle size) of silica is preferably 16 nm or less, more preferably 15 nm or less. It can be considered that by using small-particle-size silica, the contact frequency with the polymer (styrene region) of styrene-butadiene rubber (SBR) is increased, thereby further improving the anti-scraping performance. While not particularly limited to a lower limit, a particle size greater than 8 nm is preferred, and more preferably greater than 10 nm.

[0102] In addition, the average primary particle size can be calculated by directly observing the silica extracted from the rubber composition cut from the tire using an electron microscope (TEM), calculating the cross-sectional diameter based on the area of ​​each silica particle, and then taking the average value.

[0103] [3] Implementation

[0104] The present invention will be specifically described below based on the embodiments.

[0105] 1. Rubber composition

[0106] In the tires of the present invention, the rubber composition forming the tread (tread rubber composition) can be obtained by appropriately adjusting the type and amount of various compounding materials such as rubber components, fillers, softeners, vulcanizing agents and vulcanization accelerators described below.

[0107] (1) Compounding materials

[0108] (a) Rubber composition

[0109] As described above, low-styrene SBR and isoprene-based rubbers are used as rubber components. Other rubber components used include diene rubbers such as butadiene rubber (BR) and nitrile rubber (NBR), butyl rubbers such as butyl rubber, and thermoplastic elastomers such as styrene-butadiene-styrene block copolymer (SBS) and styrene-butadiene block copolymer (SB), which are commonly used rubbers (polymers) in tire manufacturing.

[0110] (A) SBR

[0111] The weight-average molecular weight of the SBR is, for example, greater than 100,000 and less than 2,000,000. Furthermore, in this invention, as described above, the styrene content in the SBR composition is set to 25% by mass or less. The vinyl content (1,2-bonded butadiene content) of the SBR is preferably, for example, greater than 5% by mass and less than 70% by mass. Moreover, the vinyl content of the SBR refers to the 1,2-bonded butadiene content within the SBR composition relative to the total butadiene portion. Furthermore, the structural identification of the SBR (determination of styrene content and vinyl content) can be performed, for example, by NMR determination. 1 H-NMR, 13 The analysis was performed using C-NMR. The compositional amounts of "styrene content," "vinyl content," etc., were correlated with the complex elastic modulus (E). * Since the physical properties of rubber components differ, true values ​​exist that are independent of the measurement method. Therefore, it is preferable to use a measurement method with the highest possible accuracy. Furthermore, the SBR content in 100 parts by mass of the rubber component is as described above.

[0112] There are no particular limitations on the type of SBR used; for example, emulsion-polymerized styrene-butadiene rubber (E-SBR) and solution-polymerized styrene-butadiene rubber (S-SBR) can be used. The SBR can be either unmodified or modified. Furthermore, hydrogenated SBRs, which involve hydrogenating the butadiene portion of the SBR, can also be used. Hydrogenated SBRs can be obtained by subsequently hydrogenating the BR portion of the SBR, or by copolymerizing styrene, ethylene, and butadiene to obtain the same structure.

[0113] As a modified SBR, any SBR having functional groups that can interact with fillers such as silica is acceptable. Examples include end-modified SBRs (end-modified SBRs with the aforementioned functional groups at the ends) which are modified by a compound (modifier) ​​having the aforementioned functional groups, main-chain modified SBRs with the aforementioned functional groups in the main chain, main-chain end-modified SBRs with the aforementioned functional groups in both the main chain and the ends (e.g., main-chain end-modified SBRs with the aforementioned functional groups in the main chain and at least one end modified by the aforementioned modifier), and end-modified SBRs modified (coupled) by a polyfunctional compound having two or more epoxy groups in the molecule and introducing hydroxyl or epoxy groups.

[0114] Examples of the aforementioned functional groups include, for example, amino, amide, silyl, alkoxysilyl, isocyanate, imino, imidazo, urea, ether, carbonyl, oxycarbonyl, mercapto, thioether, dithioether, sulfonyl, sulfinyl, thiocarbonyl, ammonium, imide, hydrazine, azo, diazo, carboxyl, nitrile, pyridyl, alkoxy, hydroxyl, oxygen, and epoxy groups. Furthermore, these functional groups may also have substituents.

[0115] Furthermore, as a modified SBR, for example, an SBR modified by a compound (modifier) ​​represented by the following formula can be used.

[0116]

Chemical Formula 1

[0117]

[0118] Furthermore, in the formula, R 1 R 2 and R 3 Same or different, indicating alkyl, alkoxy, siloxy, acetal, carboxyl (-COOH), mercapto (-SH) or their derivatives. R 4 and R 5 Same or different, indicating hydrogen atoms or alkyl groups. R 4 and R 5 It can also bond and form a ring structure with nitrogen atoms. n represents an integer.

[0119] As a modified SBR modified by a compound (modifier) ​​represented by the above formula, an SBR obtained by modifying the polymerization end (active end) of solution-polymerized styrene-butadiene rubber (S-SBR) by a compound represented by the above formula can be used (modified SBR, etc. as described in Japanese Patent Application Publication No. 2010-111753).

[0120] As R 1 R 2 and R 3 Preferably, it is an alkoxy group (preferably with 1 to 8 carbon atoms, more preferably an alkoxy group with 1 to 4 carbon atoms). As R 4 and R 5 Preferably, it is an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms). n is preferably 1 to 5, more preferably 2 to 4, and even more preferably 3. Furthermore, R 4 and R 5 When the bond combines with a nitrogen atom to form a ring structure, a 4- to 8-membered ring is preferred. Furthermore, alkoxy groups also include cycloalkoxy groups (such as cyclohexyloxy) and aryloxy groups (such as phenoxy and benzyloxy).

[0121] Specific examples of the aforementioned modifiers include 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, and 3-diethylaminopropyltriethoxysilane. These can be used alone or in combination of two or more.

[0122] In addition, modified SBRs can also be used as modified SBRs by the following compounds (modifiers). As modifiers, these include, for example, polyglycidyl ethers of polyols such as ethylene glycol diglycidyl ether, glycerol triglycidyl ether, trimethylolethane triglycidyl ether, and trimethylolpropane triglycidyl ether; polyglycidyl ethers of aromatic compounds having two or more phenolic groups such as bisphenol A diglycidyl ether; polyepoxide compounds such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxy liquid polybutadiene; tertiary amines containing epoxy groups such as 4,4'-diglycidyl diphenylmethylamine and 4,4'-diglycidyl dibenzylmethylamine; diglycidyl aniline, N,N'-diglycidyl- 4-Glycidoxyaniline, diglycidyl-o-toluidine, tetraglycidyl-m-xylenediamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, tetraglycidyl-1,3-diaminomethylcyclohexane, and other diglycidylamino compounds; bis-(1-methylpropyl)carbamoyl chloride, 4-morpholine carbamoyl chloride, 1-pyrrolidine carbamoyl chloride, N,N-dimethylcarbamoyl chloride, N,N-diethylcarbamoyl chloride, and other amino-containing acyl chlorides; 1,3-bis-(glycidoxypropyl)-tetramethyldisiloxane, (3-glycidoxypropyl) Silane compounds containing epoxy groups, such as (trimethylsilyl)-pentamethyldisiloxane; (trimethylsilyl)[3-(trimethoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(triethoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(tripropoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(tributoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(methyldimethoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(methyldiethoxysilyl)propyl] sulfide, (trimethylsilane) Silane compounds containing thioether groups, such as (trimethylsilyl)[3-(methyldipropoxysilyl)propyl] sulfide and (trimethylsilyl)[3-(methyldibutoxysilyl)propyl] sulfide; N-substituted aziridine compounds such as ethyleneimine and propyleneimine; alkoxysilanes such as methyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, and N,N-bis(trimethylsilyl)aminoethyltriethoxysilane.4-N,N-dimethylaminobenzophenone, 4-N,N-di-tert-butylaminobenzophenone, 4-N,N-diphenylaminobenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(diphenylamino)benzophenone, N,N,N',N'-bis(tetraethylamino)benzophenone, and other (thio)benzophenone compounds having amino and / or substituted amino groups; 4-N,N-dimethylaminobenzaldehyde, 4- N,N-Diphenylaminobenzaldehyde, 4-N,N-Divinylaminobenzaldehyde, and other benzaldehyde compounds containing amino groups and / or substituted amino groups; N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, N-tert-butyl-2-pyrrolidone, N-methyl-5-methyl-2-pyrrolidone, and other N-substituted pyrrolidones; N-methyl-2-piperidinone, N-vinyl-2-piperidinone, N-phenyl-2-piperidinone, and other N-substituted pyrrolidones. Besides N-substituted lactams such as piperidinone, N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-laurolactam, N-vinyl-ω-laurolactam, N-methyl-β-propiolactam, and N-phenyl-β-propiolactam, other examples include 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, N,N-diethylacetamide, N-methylmaleimide, N,N-diethylurea, 1,3-dimethylethylidene urea, 1,3-divinylethylidene urea, 1,3-diethyl-2-imidazolinone, 1-methyl-3-ethyl-2-imidazolinone, 4-N,N-dimethylaminoacetophenone, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-propanone, 1,7-bis(methylethylamino)-4-heptanone, etc. Furthermore, modification based on the above compounds (modifiers) can be carried out by known methods.

[0123] As an SBR (Self-Borne Blender), for example, SBRs manufactured / commercially available from companies such as Sumitomo Chemical Co., Ltd., ENEOS MATERIALS Co., Ltd., Asahi Kasei Corporation, and Zeon Corporation of Japan can be used. Furthermore, SBRs can be used alone or in combination of two or more types.

[0124] (B) Isoprene-based rubber

[0125] As described above, examples of isoprene-based rubbers include natural rubber (NR), modified natural rubber (modified NR), modified natural rubber (modified NR), synthetic polyisoprene (isoprene rubber (IR), modified isoprene rubber (modified IR), etc., but among these, NR, which has excellent strength, is preferred. Furthermore, the content of isoprene-based rubber in 100 parts by mass of the rubber component is as described above.

[0126] Specific types of natural rubber (NR) can be used, such as SVR-L, SIR20, RSS#3, and TSR20, which are commonly used in the tire industry. For natural rubber (IR), there are no specific limitations; for example, IR2200, a commonly used material in the tire industry, can be used. Examples of modified NRs include deproteinized natural rubber (DPNR) and high-purity natural rubber (UPNR); examples of modified NRs include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber; examples of modified IRs include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These can be used individually or in combination of two or more.

[0127] (C)BR

[0128] In this invention, BR may be further included as needed. In this case, the BR content in 100 parts by weight of the rubber component is preferably 5 parts by weight or more, more preferably 10 parts by weight or more. On the other hand, it is preferably 20 parts by weight or less, more preferably 15 parts by weight or less.

[0129] 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 less than 98% by mass. The trans content of BR is, for example, greater than 1% by mass and less than 60% by mass.

[0130] There are no particular limitations on the type of BR used; BRs with high cis content (cis content ≥ 90%), low cis content, and BRs containing syndiotactic polybutadiene crystals can be used. BRs can be either unmodified or modified; modified BRs include those incorporating the aforementioned functional groups. These can be used individually or in combination. Furthermore, the cis content can be determined by infrared absorption spectroscopy.

[0131] As a BR (Brandinger), products from companies such as Ube Industries, Ltd., Enos Materials Co., Ltd., Asahi Kasei Corporation, and Zeon Corporation can be used.

[0132] (D) Other rubber components

[0133] In addition, as other rubber components, it may also contain rubbers (polymers) commonly used in tire manufacturing, such as nitrile rubber (NBR), as needed.

[0134] The raw materials (monomers) of the aforementioned synthetic rubbers such as SBR and BR can be substances derived from petroleum, or substances recycled from rubber products such as tires and non-rubber products such as polystyrene.

[0135] The monomer obtained through recycling (recycled monomer) is not particularly limited, and examples include butadiene derived from recycling and aromatic vinyl compounds derived from recycling. Examples of butadiene include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyl compounds are not particularly limited, and examples include styrene. Preferably, butadiene derived from recycling (recycled butadiene) and / or styrene derived from recycling (recycled styrene) are used as raw materials.

[0136] There are no particular limitations on the manufacturing method of the recycled monomer. For example, it can be synthesized from recycled naphtha obtained by pyrolyzing rubber products such as tires. Furthermore, there are no particular limitations on the manufacturing method of the recycled naphtha. For example, rubber products such as tires can be pyrolyzed under high temperature and pressure, microwave pyrolysis can be used, or extraction can be performed after mechanical crushing.

[0137] Furthermore, the raw materials (monomers) for synthetic rubbers such as SBR and BR can also be substances derived from biomass. There are no particular limitations on what constitutes a biomass-derived monomer (biomass monomer), butadiene derived from biomass and aromatic vinyl compounds derived from biomass are examples. Examples of butadiene include 1,2-butadiene and 1,3-butadiene. Examples of aromatic vinyl compounds include styrene, etc. In addition, there are no particular limitations on the methods for manufacturing biomass monomers; for example, substances derived from biological and / or chemical and / or physical transformations of plants and animals can be listed. As for biological transformations, microbial fermentation is representative; as for chemical and / or physical transformations, catalyst-based transformations, high-temperature transformations, high-pressure transformations, electromagnetic wave transformations, supercritical fluid transformations, and combinations thereof can be listed. Biomass sources for these monomers can include sugar or wood, plant residues after the extraction of useful components, plant-derived ethanol, biomass naphtha, etc.

[0138] The term "biomass polymer" is not particularly limited to polymers synthesized from biomass monomer components, but examples include polybutadiene rubber synthesized from butadiene derived from biomass, and aromatic vinyl compound / butadiene copolymers synthesized from butadiene derived from biomass and / or aromatic vinyl compounds derived from biomass. Examples of such aromatic vinyl compound / butadiene copolymers include, for instance, styrene-butadiene rubber synthesized from butadiene derived from biomass and / or styrene derived from biomass.

[0139] Whether the raw material of a polymer is derived from biomass can be determined by measuring pMC (percent Modern Carbon) according to ASTM D6866-10.

[0140] pMC refers to: the sample14 C concentration relative to standard modern carbon (modern standard reference). 14 The C concentration ratio is a value used as an indicator of the biomass proportion of the compound (rubber). The significance of this value is described below.

[0141] One mole of carbon atoms (6.02 × 10⁻⁶) 23 Of these, approximately one trillionth exists, which is about 6.02 × 10⁻⁶ carbon atoms. 11 indivual 14 C. 14 Carbon (C) is known as a radioactive isotope with a half-life of 5730 years, decreasing regularly. All of these decay over a period of 226,000 years. Therefore, it can be assumed that carbon dioxide and other atmospheric substances, after being absorbed and fixed by plants and other organisms, have undergone more than 226,000 years of decay in fossil fuels such as coal, oil, and natural gas. The carbon dioxide contained in these fossil fuels at the time of initial fixation... 14 All carbon (C) decays. Therefore, in the 21st century, fossil fuels such as coal, oil, and natural gas contain absolutely no carbon. 14 Therefore, the chemicals produced using these fossil fuels as raw materials also contain absolutely no carbon (C). 14 C element.

[0142] on the other hand, 14 Carbon is continuously generated in the atmosphere through nuclear reactions caused by cosmic rays, reaching a balance with the reduction based on radioactive decay in Earth's atmospheric environment. 14 The amount of C is constant. Therefore, in the current environment, the matter originating from biomass resources in the material cycle... 14 The C concentration, as described above, is approximately 1 × 10⁻⁶ relative to all C atoms. -12 The values ​​are approximately 10% in moles. Therefore, by using the differences between these values, it is possible to calculate the proportion of compounds derived from natural resources (compounds derived from biomass resources) in a certain compound (rubber) (biomass ratio).

[0143] Typically, the 14 C was determined as described below. Accelerator mass spectrometry based on a tandem accelerator was used for the determination. 13 C concentration ( 13 C / 12 C) 14 C concentration ( 14 C / 12 C) Determination. During the determination, as... 14 The standard reference for carbon concentration is modern carbon, which uses the carbon cycling data in nature as of 1950. 14C concentration. As a specific standard substance, oxalic acid standard provided by NIST (National Institute of Standards and Technology) was used. The radioactivity of carbon in this oxalic acid (carbon content per gram of carbon) was determined. 14 The radioactivity intensity of carbon (C) is classified according to its carbon isotopes. 13 The C-correction is a fixed value, using the value with attenuation correction applied from 1950 to the date of measurement as the standard. 14 The C concentration value (100%) is used. The ratio of the actual measured value of the sample to this value is the pMC value.

[0144] Therefore, if the rubber is made entirely from biomass (natural sources), it is expected to have a value of around 110 pMC, despite regional variations (though it is rarely 100 under normal circumstances). On the other hand, for chemicals derived from fossil fuels such as petroleum, the measured... 14 At C concentrations, the value is around 0 pMC (e.g., 0.3 pMC). This value corresponds to 0% of the biomass ratio mentioned above.

[0145] In summary, from the perspective of contributing to environmental protection and improving sustainability, it is preferable to use materials such as rubber with high pMC values, that is, materials such as rubber with a high proportion of biomass, in rubber compositions.

[0146] (b) Compound materials other than rubber components

[0147] (A) Filler

[0148] As described above, the rubber composition contains silica as a reinforcing filler, but in addition to silica, it may also contain, for example, carbon black, graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, mica, etc.

[0149] (i-1)Silica

[0150] From the perspective of achieving good resistance to spalling, the BET specific surface area of ​​silica is preferably greater than 140 m². 2 / g, more preferably greater than 160m 2 / g. On the other hand, from the viewpoint of obtaining good rolling resistance at high speeds, a value of less than 300m is preferred. 2 / g, more preferably less than 250m 2 / g, more preferably less than 220m 2 / g. Furthermore, the BET specific surface area mentioned above is the N2SA value determined by the BET method according to ASTM D3037-93.

[0151] At this point, the particle size (average primary particle size) of the silica is preferably 16 nm or less, as described above. Furthermore, the silica content relative to 100 parts by mass of the rubber component is as described above.

[0152] Specific types of silica include, for example, dry-process silica (anhydrous silica) and wet-process silica (hydrated silica). Wet-process silica is preferred due to its higher silanol group content. Alternatively, silica made from materials such as aqueous glass or biomass materials such as rice husks can also be used.

[0153] For example, products from Evonik Industries, Rhodia, Tosoh Silicon Chemical Co., Ltd., Solvay Japan Co., Ltd., Tokuyama Co., Ltd., etc., can be used as silicon dioxide.

[0154] There are no particular limitations on the raw materials used for silica. For example, it can be derived from minerals such as quartz, or from biological sources such as rice husks (e.g., silica made from biomass materials such as rice husks). Silica recycled from silica-containing products can also be used. Among these, hydrated silica prepared by a wet process is preferred due to its higher silanol group content.

[0155] Silica obtained from biomass materials, for example, can be extracted from rice husk ash obtained by burning rice husks using sodium hydroxide solution. The silicate is then reacted with sulfuric acid in the same way as conventional wet silica to form silica precipitate, which is then filtered, washed with water, dried, and pulverized.

[0156] Silica recovered from products containing silica can be, for example, silica recovered from products containing silica such as electronic components like semiconductors, tires, desiccants, and filter materials such as diatomaceous earth. Furthermore, the method of recovery is not particularly limited, and examples include thermal decomposition and electromagnetic wave-based decomposition. Of these, silica recovered from electronic components like semiconductors or tires is preferred.

[0157] If silica crystallizes, it becomes insoluble in water and cannot utilize the silicic acid that is its component. By managing the combustion temperature and combustion time, the crystallization of silica in rice husk ash can be suppressed (see Japanese Patent Application Publication No. 2009-2594, Akita Prefectural University Online Journal B, 2019, vol.6, pp.216-222, etc.).

[0158] Amorphous silica extracted from rice husks can be obtained from commercially available materials such as those from Wilmar.

[0159] Furthermore, these silicas can be used alone or in combination with two or more types. Moreover, from the perspective of contributing to environmental protection and improving sustainability, biomass silica and recycled silica are preferred.

[0160] (i-2) Silane coupling agent

[0161] When using the above-mentioned silica, it is preferable to include a silane coupling agent together with the silica.

[0162] As a silane coupling agent, there are no particular limitations; examples include bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, and bis(4-trimethoxysilylethyl)tetrasulfide. 3-Triethoxysilylpropyl disulfide, 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-di Sulfide systems including methylthiocarbamoyl tetrasulfide, 2-triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide, and 3-triethoxysilylpropyl methacrylate monosulfide; thiol-based systems including 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and Momentive's NXT and NXT-Z; and vinyltriethoxysilane, vinyltrimethoxysilane, and other vinyl compounds. The coupling agents include: amino-based silanes such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidyloxy-based silanes such as γ-glycidyloxypropyltriethoxysilane and γ-glycidyloxypropyltrimethoxysilane; nitro-based silanes such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chlorinated silanes such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Among these, mercapto-based silane coupling agents such as NXT are preferred. These can be used alone or in combination of two or more.

[0163] Products from companies such as Evonik Industries, Momentive, Shin-Etsu Silicones, Tokyo Chemical Industries, Azmax, and DuPont Toray Specialty Materials can be used as silane coupling agents.

[0164] The content of the silane coupling agent relative to 100 parts by mass of silicon dioxide is, for example, greater than 3 parts by mass and less than 25 parts by mass.

[0165] (ii) Carbon black

[0166] From the viewpoint of improving wet grip by increasing rigidity and responsiveness, the rubber composition preferably contains carbon black as a reinforcing filler in addition to silica.

[0167] The carbon black content relative to 100 parts by mass of the rubber component is preferably 2 parts by mass or more, more preferably 4 parts by mass or more. As an upper limit, for example, it is preferably 10 parts by mass or less, more preferably 8 parts by mass or less.

[0168] As for carbon black, there are no particular limitations. Examples include furnace black such as SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF, and ECF; acetylene black; thermal black such as FT and MT; and channel black such as EPC, MPC, and CC. One of these can be used alone, or two or more can be used in combination.

[0169] The preferred CTAB specific surface area (Cetyl Tri-methyl Ammonium Bromide) of carbon black is 130 m². 2 / g or more, preferably 160m 2 / g or more, further preferably 170m 2 / g or more. On the other hand, 250m is preferred. 2 / g or less, more preferably 200m 2 / g or less. Furthermore, the CTAB specific surface area is a value determined according to ASTM D3765-92.

[0170] There are no specific limitations on the specific type of carbon black used; examples include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Corporation, Shin Nippon Chemical Carbon Co., Ltd., and Columbia Carbon Co., Ltd. These can be used individually or in combination of two or more.

[0171] (iii) Other fillers

[0172] In addition to silica and carbon black, the rubber composition may further contain fillers commonly used in the tire industry, such as graphite, calcium carbonate, talc, alumina, clay, aluminum hydroxide, and mica, as needed. The content of these fillers relative to 100 parts by weight of the rubber component is, for example, greater than 0.1 parts by weight and less than 200 parts by weight.

[0173] (B) Plasticizer components

[0174] In rubber compositions, plasticizer components are preferably used as needed to ensure proper dispersion of powdered materials during mixing. Furthermore, plasticizer components here refer to substances that plasticize the rubber composition, such as processing oils, rubber component enhancers, liquid rubber, and resin components.

[0175] These plasticizers can be petroleum-derived substances, biomass-derived substances, or naphtha-derived substances recovered from rubber products or non-rubber products. Furthermore, low-molecular-weight hydrocarbon components obtained through the thermal cracking and extraction of used tires and products containing various components can also be used as plasticizers; among these, biomass-derived and recycled plasticizers are preferred as sustainable plasticizers.

[0176] Furthermore, the aforementioned plasticizer components can be used alone or in combination of two or more. In this case, the content of the plasticizer component relative to 100 parts by mass of the rubber component is preferably 40 parts by mass or more, more preferably 45 parts by mass or more, and even more preferably 50 parts by mass or more. As an upper limit, for example, it is preferably 75 parts by mass or less, more preferably 70 parts by mass or less, and even more preferably 65 parts by mass or less.

[0177] In addition, the content of plasticizer components also includes the amount of oil contained in rubber (oil-extended rubber), etc.

[0178] (i) Oil

[0179] Examples of oils include mineral oils (usually referring to processing oils), vegetable oils, or mixtures thereof. Examples of mineral oils (processing oils) include paraffinic processing oils, aromatic processing oils, and naphthenic processing oils. Examples of vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice bran oil, safflower oil, sesame oil, olive oil, sunflower seed oil, palm kernel oil, camellia oil, jojoba oil, macadamia nut oil, and tung oil. These can be used alone or in combination of two or more. Furthermore, from a life cycle assessment perspective, refined oils such as waste oil from rubber kneading mixers or automotive engine lubricants, and waste cooking oils can also be used.

[0180] As specific processing oils (mineral oils), products from companies such as Idemitsu Kosan Co., Ltd., Sankyo Oil & Chemical Co., Ltd., ENEOS Co., Ltd., Olisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Showa Shell Oil Co., Ltd., and Fuji Kosan Co., Ltd. can be used.

[0181] (ii) Liquid rubber

[0182] Liquid rubber, as listed as a plasticizer, refers to polymers that are liquid at room temperature (25°C) and are rubber components that can be extracted from vulcanized tires using acetone. Examples of liquid rubber include farnesene polymers, liquid diene polymers, and their hydrides.

[0183] Farnesene polymers refer to polymers obtained by polymerizing farnesenes, possessing structural units based on farnesenes. Farnesenes include isomers such as α-farnesene ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodecathetene) and β-farnesene (7,11-dimethyl-3-methylene-1,6,10-dodecathetene).

[0184] Farnesene polymers can be homopolymers of farnesene (farnesene homopolymers) or copolymers of farnesene and vinyl monomers (farnesene-vinyl monomer copolymers).

[0185] 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).

[0186] The weight-average molecular weight (Mw) of polystyrene-based liquid diene polymers, determined by gel permeation chromatography (GPC), is, for example, greater than 1.0 × 10⁻⁶. 3 Less than 2.0×10 5 Furthermore, in this specification, the Mw of the liquid diene polymer is a polystyrene conversion value determined by gel permeation chromatography (GPC).

[0187] The content of liquid rubber (the total content of liquid farnesene polymers, liquid diene polymers, etc.) is, for example, greater than 1 part by mass and less than 100 parts by mass relative to 100 parts by mass of rubber component.

[0188] As a liquid rubber, products from companies such as Kuraray Corporation and Clayville Corporation can be used.

[0189] (iii) Resin composition

[0190] The resin component can also function as an adhesive agent. It can be solid or liquid at room temperature. Specific resin components include, for example, rosin-based resins, styrene-based resins, coumarone-based resins, terpene-based resins, C5 resins, C9 resins, C5C9 resins, and acrylic resins. Among these, C5 and C9 resins are preferred. Specifically, dicyclopentadiene resin (DCPD resin) and AMS resin (α-methylstyrene resin) are examples of such resins. Furthermore, two or more types can be used in combination. Additionally, these resin components can be modified with groups that can react with silica, etc., as needed. The content of the resin component relative to 100 parts by mass of the rubber component is as described above.

[0191] Rosin-based resins are resins whose main component is rosin acid, obtained through the processing of rosin. These rosin-based resins (rosin derivatives) can be classified based on whether they are modified or not, into unmodified rosin and modified rosin derivatives. Examples of unmodified rosin include tall oil rosin, resin rosin, wood rosin, disproportionated rosin, polymerized rosin, hydrogenated rosin, and other chemically modified rosin. Modified rosin derivatives are modified forms of unmodified rosin, and examples include rosin esters, unsaturated carboxylic acid-modified rosin derivatives, unsaturated carboxylic acid-modified rosin esters, rosin amide compounds, and rosin amine salts.

[0192] Styrene-based resins are polymers that use styrene-based monomers as constituent monomers. Examples include polymers polymerized with styrene-based monomers as the main component (50% by mass or more). Specifically, in addition to homopolymers formed by homopolymerizing styrene-based monomers (styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc.), copolymers formed by copolymerizing two or more styrene-based monomers, copolymers of styrene-based monomers with other monomers that can be copolymerized with them can also be listed.

[0193] Examples of other monomers mentioned above include acrylonitriles such as acrylonitrile and methacrylonitrile; unsaturated carboxylic acids such as acrylic acid and methacrylic acid; unsaturated carboxylic acid esters such as methyl acrylate and methyl methacrylate; dienes such as chloroprene, butadiene, and isoprene; alkenes such as 1-butene and 1-pentene; and α,β-unsaturated carboxylic acids or their anhydrides such as maleic anhydride.

[0194] Among coumarone-based resins, coumarone-indene resin is preferred. Coumarin-indene resin is a resin containing coumarone and indene as monomeric components constituting the resin backbone (main chain). Other monomeric components besides coumarone and indene contained in the backbone include styrene, α-methylstyrene, methylindene, and vinyltoluene.

[0195] The content of coumarin indole resin relative to 100 parts by weight of rubber component is, for example, greater than 1.0 parts by weight and less than 50.0 parts by weight.

[0196] The hydroxyl value (OH value) of coumarin indole resin is, for example, greater than 15 mg KOH / g and less than 150 mg KOH / g. Furthermore, the OH value refers to the amount of potassium hydroxide required, expressed in milligrams, to neutralize the acetic acid bonded to the hydroxyl group when 1 g of the resin is acetylated; this value is determined by potentiometric titration (JIS K 0070:1992).

[0197] The softening point of coumarin indene resin is, for example, greater than 30°C and less than 160°C. Furthermore, the softening point is the temperature at which the ball drops when measured using a ring-and-ball softening point tester as specified in JIS K 6220-1:2001.

[0198] Examples of terpene-based resins include polyterpenes, terpene phenols, and aromatic modified terpene resins. Polyterpenes are resins obtained by polymerizing terpene compounds and their hydrides. Terpene compounds are composed of (C5H8) resins. n The composition of hydrocarbons and their oxygen-containing derivatives is represented by the class of monoterpenes (C64- ... 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32 Compounds with terpenes as their basic skeleton include, for example, α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, and γ-terpineol.

[0199] As polyterpenes, in addition to terpene resins such as α-pinene resin, β-pinene resin, limonene resin, dipentene resin, and β-pinene / limonene resin, which use the aforementioned terpene compounds as raw materials, hydrogenated terpene resins that have undergone hydrogenation treatment of these terpene resins can also be listed. As terpene phenols, resins obtained by copolymerizing the aforementioned terpene compounds with phenolic compounds, as well as resins that have undergone hydrogenation treatment of these resins, can be listed. Specifically, resins obtained by condensing the aforementioned terpene compounds, phenolic compounds, and formaldehyde can be listed. Furthermore, phenolic compounds, for example, phenol, bisphenol A, cresol, xylenol, etc., can be listed. As aromatic modified terpene resins, resins obtained by modifying terpene resins with aromatic compounds, as well as resins that have undergone hydrogenation treatment of these resins, can be listed. Furthermore, as aromatic compounds, there are no particular limitations as long as the compound has an aromatic ring. Examples include phenols such as phenol, alkylphenols, alkoxyphenols, and phenols containing unsaturated hydrocarbon groups; naphthols such as naphthol, alkylnaphthol, alkoxynaphthol, and naphthols containing unsaturated hydrocarbon groups; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, and styrene containing unsaturated hydrocarbon groups; coumarone, indene, etc.

[0200] "C5 resin" refers to a resin obtained by polymerizing C5 fractions. 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 particularly preferred as a C5-based petroleum resin.

[0201] "C9 resin" refers to resins obtained by polymerizing C9 fractions, or their hydrogenated or modified products. Examples of C9 fractions include, for example, petroleum fractions with 8 to 10 carbon atoms such as vinyltoluene, alkylstyrene, indene, and methylindene. Specifically, coumarone-indene resin, coumarone resin, indene resin, and aromatic vinyl compound resins are preferred. As aromatic vinyl compound resins, homopolymers of α-methylstyrene (AMS) or styrene, or copolymers of α-methylstyrene and styrene, are preferred for economic reasons, ease of processing, and excellent exothermic properties; copolymers of α-methylstyrene and styrene are more preferred. For example, commercially available substances from companies such as Kraton and Eastman Chemical Company can be used as aromatic vinyl compound resins.

[0202] "C5C9 resin" refers to a resin obtained by copolymerizing the aforementioned C5 fraction and the aforementioned C9 fraction, or it may be a hydrogenated or modified product of them. Examples of C5 and C9 fractions include the aforementioned petroleum fractions. For example, commercially available substances from Tosoh Corporation, LUHUA Corporation, etc., can be used as C5C9 resin.

[0203] There are no particular limitations on the acrylic resin used; for example, solvent-free acrylic resins can be used.

[0204] Solvent-free acrylic resins include (meth)acrylic resins (polymers) synthesized by high-temperature continuous polymerization (high-temperature continuous bulk polymerization) without using polymerization initiators, chain transfer agents, organic solvents, etc., as byproducts (as described in US Patent No. 4,414,370, Japanese Patent Application Publication No. 59-6207, Japanese Patent Application Publication No. 5-58005, Japanese Patent Application Publication No. 1-313522, US Patent No. 5,010,166, and the Toa Synthetic Research Yearbook TREND2000 No. 3, pp. 42-45). Furthermore, in this invention, (meth)acrylic acid refers to methacrylic acid and acrylic acid.

[0205] Examples of monomeric components constituting the above-mentioned acrylic resins include (meth)acrylic acid, (meth)acrylates (alkyl esters, aryl esters, aralkyl esters, etc.), (meth)acrylamide, and (meth)acrylamide derivatives.

[0206] In addition, as monomer components constituting the above-mentioned acrylic resins, besides (meth)acrylic acid and (meth)acrylic acid derivatives, aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, and divinylnaphthalene can also be used.

[0207] The aforementioned acrylic resins can be resins composed solely of (meth)acrylic acid, or resins that also include components other than (meth)acrylic acid as constituent elements. Furthermore, the aforementioned acrylic resins may also possess hydroxyl, carboxyl, or silanol groups, etc.

[0208] As a resin component, products from companies such as Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Co., Ltd., Rutgers Chemicals, Ltd., BASF, Arizona Chemical Company, Nippon Paint Co., Ltd., Nippon Shokubai Co., Ltd., ENEOS Co., Ltd., Arakawa Chemical Industry Co., Ltd., Taoka Chemical Industry Co., Ltd., etc. can be used.

[0209] (C) Stearic acid

[0210] The rubber composition preferably contains stearic acid. The content of stearic acid relative to 100 parts by weight of the rubber component is, for example, greater than 0.5 parts by weight and less than 10.0 parts by weight. As stearic acid, conventionally known substances can be used, such as products from Nippon Oil Co., Ltd., NOF Corporation, Kao Corporation, Fujifilm, Kojun Pharmaceutical Co., Ltd., Chiba Fatty Acid Co., Ltd., etc.

[0211] (D) Anti-aging agents

[0212] The rubber composition preferably contains an antioxidant. The antioxidant content relative to 100 parts by weight of the rubber component is preferably greater than 0.5 parts by weight and less than 10 parts by weight, more preferably 1 part by weight or more.

[0213] Examples of antioxidants include naphthylamine-based antioxidants such as phenyl-α-naphthylamine; diphenylamine-based antioxidants such as octyl diphenylamine and 4,4′-bis(α,α'-dimethylbenzyl)diphenylamine; p-phenylenediamine-based antioxidants such as N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, and N,N'-di-2-naphthyl-p-phenylenediamine; quinoline-based antioxidants such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based antioxidants such as 2,6-di-tert-butyl-4-methylphenol and styreneated phenol; and bis, tri, and polyphenol-based antioxidants such as tetra[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane. These can be used individually or in combination of two or more.

[0214] In addition, as an anti-aging agent, products from companies such as Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinsei Chemical Co., Ltd., and FLEXSYS can be used.

[0215] (E) Wax

[0216] The rubber composition preferably contains wax. The wax content is, for example, 0.5 to 20 parts by weight of the rubber component per 100 parts by weight, preferably 1.0 to 15 parts by weight, and more preferably 1.5 to 10 parts by weight.

[0217] As for waxes, there are no particular limitations. Examples include petroleum-based waxes such as paraffin wax and microcrystalline wax; natural waxes such as plant-based waxes and animal-based waxes; and synthetic waxes such as polymers of ethylene and propylene. These can be used alone or in combination of two or more.

[0218] In addition, as a wax, products from companies such as Ouchi Shinshin Chemical Industry Co., Ltd., Nippon Seiwa Co., Ltd., and Seiko Chemical Co., Ltd. can be used.

[0219] (F) Zinc oxide

[0220] The rubber composition may also contain zinc oxide. The content of zinc oxide is, for example, greater than 0.5 parts by weight and less than 10 parts by weight per 100 parts by weight of the rubber component. As zinc oxide, conventionally known substances can be used, such as products from Mitsui Metal Mining Co., Ltd., Toho Co., Ltd., HAKUSUI TECH Co., Ltd., Seido Chemical Industry Co., Ltd., Sakai Chemical Industry Co., Ltd., etc.

[0221] (G) Crosslinking agents and vulcanization accelerators

[0222] The rubber composition preferably contains a crosslinking agent such as sulfur. The content of the crosslinking agent is, for example, greater than 0.1 parts by weight and less than 10.0 parts by weight per 100 parts by weight of the rubber component.

[0223] As for sulfur, examples commonly used in the rubber industry include powdered sulfur, settled sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, and soluble sulfur. These can be used individually or in combination of two or more.

[0224] In addition, products made from companies such as Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., FLEXSYS, Nippon Kanryu Kogyo Co., Ltd., and Hosoi Chemical Industry Co., Ltd. can be used as sulfur.

[0225] Examples of crosslinking agents other than sulfur include sulfur-containing vulcanizing agents such as TACKIROL V200 manufactured by Taoka Chemical Industry Co., Ltd., KA9188 (1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane) manufactured by Lanxess Co., Ltd., and organic peroxides such as dicumyl peroxide.

[0226] The rubber composition preferably contains a vulcanization accelerator. The content of the vulcanization accelerator relative to 100 parts by weight of the rubber component is, for example, greater than 0.3 parts by weight and less than 10.0 parts by weight.

[0227] Examples of vulcanization accelerators include thiazole-based accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazole disulfide, and N-cyclohexyl-2-benzothiazole sulfenamide; thiuram-based accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetra(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based accelerators such as N-cyclohexyl-2-benzothiazole sulfenamide, N-tert-butyl-2-benzothiazole sulfenamide, N-oxoethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based accelerators such as diphenylguanidine, di-o-toluidine, and o-toluidine biguanide. These can be used alone or in combination of two or more.

[0228] (H) Other

[0229] In addition to the components mentioned above, the rubber composition may be further formulated with additives commonly used in the tire industry, such as fatty acid metal salts, carboxylic acid metal salts, organic peroxides, and anti-reversion (vulcanization reversion) agents, as needed. The content of these additives relative to 100 parts by weight of the rubber component is, for example, greater than 0.1 parts by weight and less than 200 parts by weight.

[0230] (2) Preparation of rubber composition

[0231] The tread rubber composition can be appropriately adjusted by adjusting the various compounding materials mentioned above, and can be manufactured by conventional methods, for example, by a manufacturing method including the following steps: a basic kneading step by mixing the rubber components with fillers such as silica and carbon black, and a final kneading step by mixing the mixture obtained in the basic kneading step with a crosslinking agent.

[0232] Mixing can be carried out using known (closed) mixing machines such as Banbury internal mixers, kneaders, and open roll mills.

[0233] The mixing temperature in the basic kneading process is, for example, greater than 50°C and less than 200°C, and the mixing time is, for example, greater than 30 seconds and less than 30 minutes. In addition to the above-mentioned components, in the basic kneading process, compounding agents used in the rubber industry in the past can be added as needed, such as softeners such as oils, zinc oxide, antioxidants, waxes, vulcanization accelerators, etc., and then mixed.

[0234] In the final refining process, the mixture obtained in the basic kneading process is kneaded with a crosslinking agent. The kneading temperature in the final refining process is, for example, above room temperature and below 80°C, and the kneading time is, for example, above 1 minute and below 15 minutes. In addition to the above-mentioned components, vulcanization accelerators, zinc oxide, etc., may be added as needed in the final refining process.

[0235] 2. Tire manufacturing

[0236] The tires involved in this invention can be manufactured as uncured tires by forming a tread rubber of a predetermined shape using a rubber composition obtained above, and then forming it together with other tire components on a tire forming machine using conventional methods.

[0237] Specifically, an uncured tire is manufactured by winding an inner liner (which is a component to ensure the airtightness of the tire), a carcass (which is a component to bear the load, impact and air pressure of the tire), and a belt layer (which is a component to strongly fasten the carcass and improve the tread rigidity) onto a forming drum. A bead portion is also configured to fix the two ends of the carcass to the two side edges and fix the tire to the rim. After being formed into a ring shape, the tire sidewall is formed by attaching the tread to the center of the outer periphery and attaching the sidewall to the radial outer side.

[0238] Then, the uncured tires are heated and pressurized in a vulcanizing machine to obtain tires. The vulcanization process can be carried out using known vulcanization methods. For example, the vulcanization temperature is 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.

[0239] As previously described, the resulting tire exhibits improved blockage resistance due to the synergistic effect of various factors, including the appropriate control of the formulation, physical properties (loss tangent, complex modulus of elasticity), and main groove depth of the tread rubber composition.

[0240] Furthermore, the tires involved in this invention are not limited to a specific classification and can be used as tires for passenger cars, large passenger cars, large SUVs, trucks / buses, two-wheeled vehicles, racing tires, studless anti-skid tires (winter tires), all-season tires, run-flat tires, aircraft tires, mining tires, non-pneumatic tires, etc., but are preferably set as tires for passenger cars.

[0241]

Example

[0242] The following are examples (embodiments) that are considered preferred in practice, but the scope of the invention is not limited to these embodiments.

[0243] The treads formed from the various compound materials shown below, as well as tires composed of other rubber components, were studied. The results calculated based on the following evaluation method for block resistance are shown in the lower part of Tables 1 and 2.

[0244] 1. Manufacturing of rubber compositions for tire treads

[0245] Rubber compositions for tire treads are prepared using the various compounding materials shown below.

[0246] (1) Compounding materials

[0247] (a) Rubber composition

[0248] (A) NR: TSR-20

[0249] (B) SBR-1: Modified S-SBR manufactured based on Manufacturing Example 1 below (styrene content: 25% by mass, vinyl content: 25% by mol%, Tg: -50°C, Mw: 750,000).

[0250] (C) SBR-2: Modified S-SBR manufactured based on Manufacturing Example 2 below (styrene content: 20% by mass, vinyl content: 20% by mol%, Tg: -60°C, Mw: 650,000).

[0251] (D) SBR-3: HPR840 (S-SBR) manufactured by ENEOS MATERIALS (styrene content: 10% by mass, vinyl content: 42% by mol%, Tg: -63℃)

[0252] (E) SBR-4: HPR850 (S-SBR) manufactured by ENEOS MATERIALS (styrene content: 27.5% by mass, vinyl content: 59% by mol%, Tg: -25℃)

[0253] (F)BR: Ube Industries UBEPOL BR150B (high-cision BR) manufactured by Ube Industries.

[0254] (cis content 97% by mass, trans content 2% by mass, vinyl content 1% by mass)

[0255] (Manufacturing Example 1: Manufacturing of SBR-1)

[0256] The SBR-1 described above was prepared according to the following steps. First, cyclohexane, tetrahydrofuran, styrene, and 1,3-butadiene were added to a nitrogen-purged autoclave reactor. After adjusting the temperature of the reactor contents, n-butyllithium was added to initiate polymerization. Then, polymerization was carried out under adiabatic conditions. At the point where the polymerization conversion reached 99%, 1,3-butadiene was added to further polymerize for 5 minutes. N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane was added as a modifier, and the reaction was continued. After the polymerization reaction was completed, 2,6-di-tert-butyl-p-cresol was added, and the solvent was removed by steam stripping. The product was then dried by hot roller drying to obtain SBR-1.

[0257] (Manufacturing Example 2: Manufacturing of SBR-2)

[0258] Except for changing the target styrene content, vinyl content, and Tg, and setting the modifier as 3-dimethylaminopropyltriethoxysilane, the above-mentioned SBR-2 was obtained in the same manner as in Manufacturing Example 1.

[0259] (b) Compound materials other than rubber components

[0260] (A) Silica: ULTRASIL 9100Gr manufactured by Evonik Industries

[0261] (N2SA: 235m) 2 / g, average particle size: 15nm)

[0262] (B) Silane coupling agent: NXT manufactured by Momentive.

[0263] (3-Octaylthiopropyltriethoxysilane)

[0264] (C) Carbon black: DIABLACK N220 manufactured by Mitsubishi Chemical Corporation

[0265] (N2SA: 115m) 2 / g)

[0266] (D) Resin composition: SYLVATRAXX 4401 manufactured by Arizona Chemical Company

[0267] (α-Methylstyrene resin)

[0268] (E) Oil: Vivatec 500 manufactured by H&R.

[0269] (Aromatic processing oil: TDAE oil)

[0270] (F) Zinc oxide: Zinc oxide No. 2 manufactured by Mitsui Metals & Mining Co., Ltd.

[0271] (G) Antioxidant: Antigen E 6C manufactured by Sumitomo Chemical Co., Ltd.

[0272] (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine)

[0273] (H) Stearic acid: TSUBAKI stearic acid beads manufactured by Nippon Oil Company.

[0274] (I) Wax: OZOACE 0355 manufactured by Nippon Fine Wax Co., Ltd.

[0275] (J) Sulfur: Powdered sulfur (containing 5% oil) manufactured by Tsurumi Chemical Industry Co., Ltd.

[0276] (K) Vulcanization accelerator: NOCCELER CZ manufactured by Ouchi Shinshin Chemical Industry Co., Ltd.

[0277] (N-Cyclohexyl-2-benzothiazole sulfenamide (CBS))

[0278] (2) Preparation of rubber composition for tire tread

[0279] Based on the formulations shown in Tables 1 and 2, the materials other than sulfur and vulcanization accelerator were mixed at 150°C for 5 minutes using a 1.7L Banbury internal mixer manufactured by Kobe Steel Corporation to obtain the mixture.

[0280] Then, sulfur and vulcanization accelerator are added to the mixture, and it is kneaded for 5 minutes at 80°C using an open rolling mill to obtain the rubber compositions for each tire tread.

[0281] 2. Manufacturing of pneumatic tires

[0282] (1) Tread Formation

[0283] Then, using the rubber composition obtained above, the tire tread is formed into a specified shape with the main groove depths shown in Tables 1 and 2.

[0284] Then, it is bonded together with other tire components to form an uncured tire, and then vulcanized under pressure at 170°C for 10 minutes to manufacture the test tires of Examples 1 to 7 and Comparative Examples 1 to 5 shown in Tables 1 and 2 (tire size: 175 / 60R18, aspect ratio 60%, negative profile ratio: 65%).

[0285] 3. Properties of vulcanized rubber

[0286] Then, viscoelasticity test samples (30 mm long × 4.2 mm wide × 2.0 mm thick) were collected from the interior of the tread rubber layer of each test tire, with the tire circumference as the long side. Using GABO's "EPLEXOR" series viscoelasticity testers, loss tangents (0℃ tanδ, -20℃ tanδ, -30℃ tanδ, -40℃ tanδ) were measured at various test temperatures (0℃, -20℃, -30℃, -40℃) under conditions of 10 Hz frequency, 5% initial strain, 1% dynamic strain rate, and elongation deformation mode. Simultaneously, the complex elastic modulus (E0℃) was measured under conditions of 0℃ temperature, 10 Hz frequency, 5% initial strain, 1% dynamic strain rate, and elongation deformation mode. * Furthermore, the thickness direction of the sample was set to the radial direction of the tire. Additionally, when the same formulation was used in multiple embodiments, the average value was the value measured from each test tire.

[0287] Then, calculate B1 and the depth D / B1 of the main channel.

[0288] 4. Performance Evaluation (Evaluation of resistance to chipping)

[0289] Each test tire was assembled onto a standard rim, inflated to the standard internal pressure, and then mounted on all wheels of the test vehicle. The vehicle was driven at 50 km / h for 4 hours on an unpaved surface. Then, the circumferential length of all cracks that appeared on the tire surface was measured, and the maximum value was determined.

[0290] Then, the result from Comparative Example 1 is taken as 100 and exponentialized based on the following formula to evaluate the spalling resistance. The larger the value, the less cracking occurs and the better the spalling resistance.

[0291] Block resistance = [(Result of Comparative Example 1) / (Result of the test tire)] × 100

[0292] Table 1

[0293]

[0294] Table 2

[0295]

[0296] The present invention has been described above based on embodiments, but the present invention is not limited to the embodiments described above. Various modifications can be made to the above embodiments within the same and equivalent scope as the present invention.

[0297] The present invention (1) is a tire, characterized in that,

[0298] It has a tire with a tread pattern that runs along the circumferential main groove.

[0299] The tread portion is formed using a rubber composition.

[0300] The rubber composition comprises, in 100 parts by weight of rubber components, more than 60 parts by weight of styrene-butadiene rubber (SBR) with a styrene content of less than 25% by weight, and more than 10 parts by weight of isoprene-based rubber. Further, relative to 100 parts by weight of rubber components, the rubber composition comprises more than 105 parts by weight of silica and more than 25 parts by weight of resin components.

[0301] The complex elastic modulus of the tread area is 0°CE. * (MPa) and the loss tangents of the tread portion (0℃tanδ, -20℃tanδ, -30℃tanδ, -40℃tanδ) satisfy the following equation (1), and the complex elastic modulus E at 0℃ * (MPa) was measured at a temperature of 0℃, a frequency of 10Hz, an initial strain of 5%, a dynamic strain rate of 1%, and a deformation mode of elongation. The loss tangents (0℃ tanδ, -20℃ tanδ, -30℃ tanδ, -40℃ tanδ) were measured at a frequency of 10Hz, an initial strain of 5%, a dynamic strain rate of 1%, and a deformation mode of elongation, at temperatures of 0℃, -20℃, -30℃, and -40℃.

[0302] The following equation (2) applies to B1 as shown in equation (1) and the depth D (mm) of the main trench.

[0303] B1[={(-40℃tanδ)+(-30℃tanδ)+(-20℃tanδ)}×0℃tanδ / 0℃E * ]>0.005 (1)

[0304] D / B1<1000 (2)

[0305] This invention (2) is the tire described in this invention (1), characterized in that,

[0306] The value B1 is greater than 0.010.

[0307] This invention (3) is the tire described in this invention (2), characterized in that,

[0308] The value B1 is greater than 0.015.

[0309] The present invention (4) is a tire of any combination of any one of the present inventions (1) to (3), characterized in that,

[0310] The styrene content of the styrene-butadiene rubber (SBR) in the rubber composition is less than 20% by mass.

[0311] The present invention (5) is the tire described in the present invention (4), characterized in that,

[0312] The styrene content of the styrene-butadiene rubber (SBR) in the rubber composition is less than 15% by mass.

[0313] The present invention (6) is a tire of any combination of any one of the present inventions (1) to (5), characterized in that,

[0314] The content (parts by mass) of the resin component relative to 100 parts by mass of the rubber component is less than 40 parts by mass.

[0315] The present invention (7) is a tire of any combination of any one of the present inventions (1) to (6), characterized in that,

[0316] The resin component is dicyclopentadiene resin or α-methylstyrene resin.

[0317] The present invention (8) is a tire of any combination of any one of the present inventions (1) to (7), characterized in that,

[0318] The content of styrene-butadiene rubber (SBR) in 100 parts by mass of the rubber component is C S (parts by weight), the ratio of the tire's aspect ratio A (%) to the tire's aspect ratio A (%) (C) S / A) is greater than 1.

[0319] The present invention (9) is a tire of any combination of any one of the present inventions (1) to (8), characterized in that,

[0320] The content C of silica relative to 100 parts by mass of the rubber component SI (parts by weight), the ratio of the tire's negative profile ratio N (%) to (C) SI / N) is greater than 1.

[0321] The present invention (10) is a tire of any combination of any one of the present inventions (1) to (9), characterized in that,

[0322] The average particle size of the silica is less than 16 nm.

[0323] The present invention (11) is a tire of any combination of any one of the present inventions (1) to (10), characterized in that,

[0324] The rubber composition contains a mercapto-based silane coupling agent.

[0325] This invention (12) is a tire of any combination of any one of the claims (1) to (11) of this invention, characterized in that,

[0326] The content of styrene-butadiene rubber (SBR) in 100 parts by weight of the rubber component is greater than 65 parts by weight.

[0327] The present invention (13) is a tire of any combination of any one of the present inventions (1) to (12), characterized in that,

[0328] The content of the isoprene-based rubber in 100 parts by mass of the rubber component is greater than 15 parts by mass.

[0329] The present invention (14) is a tire of any combination of any one of the claims (1) to (13) of the present invention, characterized in that,

[0330] The content of silica in the rubber composition is less than 180 parts by weight relative to 100 parts by weight of the rubber component.

Claims

1. A tire, characterized in that, It has a tread section with a main groove along the circumferential direction of the tire. The tread portion is formed using a rubber composition. The rubber composition contains more than 60 parts by mass of styrene-butadiene rubber (SBR) with a styrene content of less than 25% by mass in 100 parts by mass of the rubber component, and more than 10 parts by mass of isoprene-based rubber. Further, relative to 100 parts by mass of the rubber component, the rubber composition contains more than 105 parts by mass of silica and more than 25 parts by mass of resin component. The complex elastic modulus of the tread area is 0°CE. * The loss tangents of the tread face at 0℃tanδ, -20℃tanδ, -30℃tanδ, and -40℃tanδ satisfy the following equation (1), and The B1 shown in equation (1) and the depth D of the main trench satisfy the following equation (2). B1[={(-40℃tanδ)+(-30℃tanδ)+(-20℃tanδ)|×0℃tanδ / 0℃E * >0.005 (1) D / B1<1000 (2) The complex elastic modulus at 0°C E * The unit is MPa, and the unit of the depth D is mm; The complex elastic modulus at 0°C E * The measurements were taken at a temperature of 0℃, a frequency of 10Hz, an initial strain of 5%, a dynamic strain rate of 1%, and a deformation mode of elongation. The loss tangents 0℃tanδ, -20℃tanδ, -30℃tanδ, and -40℃tanδ were measured at temperatures of 0℃, -20℃, -30℃, and -40℃, respectively, under the conditions of a frequency of 10Hz, an initial strain of 5%, a dynamic strain rate of 1%, and a deformation mode of elongation.

2. The tire according to claim 1, characterized in that, The value B1 is greater than 0.

010.

3. The tire according to claim 2, characterized in that, The value B1 is greater than 0.

015.

4. The tire according to any one of claims 1 to 3, characterized in that, The styrene content of the styrene-butadiene rubber (SBR) in the rubber composition is less than 20% by mass.

5. The tire according to claim 4, characterized in that, The styrene content of the styrene-butadiene rubber (SBR) in the rubber composition is less than 15% by mass.

6. The tire according to any one of claims 1 to 3, characterized in that, The content of resin component relative to 100 parts by weight of the rubber component is less than 40 parts by weight.

7. The tire according to any one of claims 1 to 3, characterized in that, The resin component is dicyclopentadiene resin or α-methylstyrene resin.

8. The tire according to any one of claims 1 to 3, characterized in that, The content C of styrene-butadiene rubber (SBR) in 100 parts by mass of the rubber component S The ratio C to the tire's aspect ratio A S / A is greater than 1, The content C S The unit is parts by mass, and the unit of the flatness ratio A is %.

9. The tire according to any one of claims 1 to 3, characterized in that, The content of silica relative to 100 parts by mass of the rubber component, C SI The ratio C to the negative profile ratio N of the tire SI / N is greater than 1, The content C SI The unit is parts by mass, and the unit of the negative profile ratio N is %.

10. The tire according to any one of claims 1 to 3, characterized in that, The average particle size of the silica is less than 16 nm.

11. The tire according to any one of claims 1 to 3, characterized in that, The rubber composition contains a mercapto-based silane coupling agent.

12. The tire according to any one of claims 1 to 3, characterized in that, The content of styrene-butadiene rubber (SBR) in 100 parts by weight of the rubber component is greater than 65 parts by weight.

13. The tire according to any one of claims 1 to 3, characterized in that, The content of the isoprene-based rubber in 100 parts by mass of the rubber component is greater than 15 parts by mass.

14. The tire according to any one of claims 1 to 3, characterized in that, The content of silica in the rubber composition is less than 180 parts by mass relative to 100 parts by mass of the rubber component.

15. The tire according to any one of claims 1 to 3, characterized in that, The styrene content of the styrene-butadiene rubber (SBR) in the rubber composition is 3% by mass or more.

16. The tire according to any one of claims 1 to 3, characterized in that, The content of styrene-butadiene rubber (SBR) in 100 parts by weight of the rubber component is less than 90 parts by weight.

17. The tire according to any one of claims 1 to 3, characterized in that, The content of the isoprene-based rubber in 100 parts by weight of the rubber component is less than 30 parts by weight.

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