Tire tread rubber for preventing groove bottom cracking and preparation method thereof

Abstract

The present invention discloses a tire tread rubber for preventing groove bottom cracking and a preparation method thereof. The technical solution thereof comprises the following components in parts by weight: 35-75 parts of natural rubber, 10-25 parts of solution-polymerized styrene-butadiene rubber, 15-35 parts of styrene-butadiene rubber SBR1502, and high-cis BR9000. 10-30 parts, 1-3 parts of zinc oxide, 22-55 parts of modified diatomaceous earth, 60-125 parts of carbon black, 1.5-4.5 parts of modified aramid fiber, 1-3.5 parts of stearic acid, 1-4.5 parts of polyethylene glycol, etc.; the present invention provides a tire tread rubber for preventing groove bottom cracking. The new and improved formula is adopted to enable the tread rubber to effectively overcome the defect of groove bottom cracking. Compared with the previous tread rubber, the tread rubber can reduce the groove bottom cracking by about 90%, effectively improve the tear resistance, wear resistance, high temperature dynamic fatigue resistance, heat aging resistance and dynamic ozone aging resistance of the rubber material, and at the same time improve the rolling resistance and wet skid resistance of the rubber material.

Description

Technical field

[0001] The invention belongs to the technical field of tire materials, and in particular relates to a tire tread rubber for preventing groove bottom cracking and a preparation method thereof. [Background Technology]

[0002] Semi-steel radial tires are currently very popular, and while launching new products is crucial for tire manufacturers, their use in the Chinese market is not as standardized as in the European and American markets, resulting in a high return rate. In addition to shoulder and bead delamination, common damage to semi-steel radial tires during use also includes crown groove bottom cracking. Crown groove bottom cracking typically occurs in the early stages of tire use. Once a crown groove bottom crack develops, the entire tire cannot be used, and tire manufacturers are not eligible for refunds for tires with crown groove bottom cracking. This can be a significant loss for users and negatively impacts tire manufacturers.

[0003] There are many reasons for tire tread cracking, including insufficient tread rubber thickness, poor tear resistance, and improperly designed tread wall angles that trap stones in the groove bottom. These cracks typically occur in the middle or later stages of tire life, presenting an acceptable loss for tire manufacturers and users, and rarely causing significant complaints. Overcoming these issues while maintaining a certain level of wear and tear resistance remains a pressing issue for the tire industry. [Summary of the invention]

[0004] The present invention discloses a tire tread rubber for preventing groove bottom cracking. The tire tread rubber adopts a new and improved formula, so that the tire tread rubber can effectively overcome the defect of groove bottom cracking. Compared with previous tread rubbers, the tire tread rubber can reduce groove bottom cracking by about 90%, effectively improve the rubber's tear resistance, wear resistance, high-temperature dynamic fatigue resistance, heat aging resistance and dynamic ozone aging resistance, and at the same time improve the rubber's rolling resistance and anti-skid performance.

[0005] The present invention also provides a method for preparing a tire tread rubber capable of preventing groove bottom cracking.

[0006] The technical solutions of the present invention are as follows:

[0007] A tire tread rubber for preventing groove bottom cracking comprises the following components in parts by weight:

[0008] 35-75 parts of natural rubber,

[0009] 10-25 parts of solution-polymerized styrene-butadiene rubber,

[0010] Styrene butadiene rubber SBR1502 15-35,

[0011] High-cis BR9000 10-30,

[0012] 1-3 parts of zinc oxide,

[0013] 22-55 parts of modified diatomaceous earth,

[0014] 60-125 parts of carbon black,

[0015] 1.5-4.5 parts of modified aramid fiber,

[0016] 1-3.5 parts of stearic acid,

[0017] 1-4.5 parts of polyethylene glycol,

[0018] 1-2.5 parts of dispersant,

[0019] Antiaging agent 2-5.5 parts,

[0020] 1-2.5 parts of tackifying resin,

[0021] 1.5-4.0 parts of antioxidant,

[0022] Anti-fatigue agent 1-3.5,

[0023] Tear-resistant resin 1-4,

[0024] 1-5.5 parts of silane coupling agent,

[0025] 1-3 parts sulfur

[0026] 2-7 parts of vulcanization accelerator.

[0027] Solution-polymerized styrene-butadiene rubber has the advantages of wear resistance, cold resistance, low heat generation, low shrinkage, good color, low ash content, high purity and fast vulcanization speed. It also has the advantages of low rolling resistance, excellent anti-skid performance and wear resistance, and meets the needs of green environmental protection. Its tire rolling resistance is reduced by 30%, anti-skid performance is improved by 3%, wear resistance is improved by 15%, and fuel consumption is also reduced accordingly.

[0028] The modified aramid fiber is Sul fron3001, preferably aramid fiber with a specification of 150D and a length of less than 1.5 mm, which is prepared by modification with sulfuric acid solution and sodium bicarbonate solution. Since the tensile strength and tear strength of styrene-butadiene rubber are lower than those of natural rubber, the amount of reinforcing carbon black and wear-resistant carbon black will be increased, and excessive heat generation of the rubber compound will cause accelerated tread aging. In order to simultaneously utilize the initial anti-cracking performance of styrene-butadiene rubber and enable it to be used in combination with natural rubber, a small amount of modified aramid fiber is added to the rubber system. The modified aramid fiber reacts with sulfur and an accelerator to form an intermediate, forming a bond between the rubber and the aramid fiber, and between the carbon black and the aramid fiber, which can enhance the interaction between the rubber and the carbon black, thereby reducing the interaction between the filler and the filler, and enhancing the interaction between the filler and the polymer. The amount of carbon black can be appropriately reduced to reduce the heat generation of the rubber compound, while maintaining the cross-linked bond network structure of the vulcanized rubber, maintaining or improving the tensile strength and other properties of the rubber compound, and further improving the cut resistance and puncture resistance of the tire tread.

[0029] Preferably, the carbon black is composed of three types of carbon black in the following weight ratio: 15-30 parts of N134 carbon black, 15-45 parts of N220 carbon black, and 25-55 parts of modified white carbon black. The white carbon black is modified with a modifier and dried and sintered at a temperature of 650°C to 750°C and a time of 1 to 3 hours.

[0030] Compared with carbon black, silica has a higher surface area, finer particles, and high surface polarity, which can effectively improve the tensile stress and tear strength of the rubber compound, reduce the chipping phenomenon, improve the flexural fatigue resistance, and reduce heat generation. However, carbon black has good wear resistance, and improving the crack resistance requires appropriate adjustment of the amount of carbon black and vulcanizer; silica is treated with the modifier (3-mercaptopropyl) trimethoxysilane to eliminate or reduce the content of silanol groups, changing the silica surface from hydrophilic to hydrophobic. At the same time, it can effectively solve the agglomeration phenomenon of silica due to the action of surface hydroxyl groups, and improve the dispersibility and processing performance of silica in the rubber compound.

[0031] Preferably, the silane coupling agent is one or more of 2-mercaptoethyltriethoxysilane, 3,3'-bis(diphenylcyclohexyloxysilylpropyl) disulfide, 3,3'-bis(ethyl-di-sec-butoxysilylpropyl) disulfide, 3,3'-bis(propyldiethoxysilylpropyl) disulfide, and 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide. In order to better combine white carbon black with solution-polymerized styrene-butadiene rubber, a dedicated silane coupling agent must be used in the presence of a vulcanization system.

[0032] Preferably, the cis structure content of high-cis BR9000, obtained by polymerization with a metal catalyst, is greater than 97%. The metal catalyst is a nickel (α-diimide) catalyst, a diethylaluminum chloride-cobalt system, or a trialkylaluminum-boron trifluoride-nickel system. High-cis BR9000, a high-cis 1,4-polybutadiene rubber, has a cis structure content of greater than 90% by mass. It exhibits high elasticity, good wear resistance, good cold resistance, low heat buildup, good flexural resistance, and excellent dynamic performance. The preferred synthetic polyisoprene elastomer for this application is one with a cis 1,4 structure content (mol%) greater than 90%, and more preferably greater than 98%.

[0033] Preferably, the antioxidant is zinc dimethyl dithiophosphate, or zinc isobutyl isooctyl dithiophosphate, or zinc dibutyl dithiophosphate; the adhesive resin is a mixture of two or more of phenolic resin, aromatic resin, hydrocarbon resin, terpene resin, indene resin, coumarone resin, and rosin-based resin.

[0034] Preferably, the vulcanization accelerator is composed of three accelerators, including 2-3 parts of N-tert-butyl-2-benzothiazolesulfenamide, 1-1.5 parts of 2-mercaptobenzothiazole, and 3-5 parts of N-cyclohexyl-bis(2-mercaptobenzothiazole)sulfenamide. The accelerators can control the vulcanization rate and vulcanization flatness. The preferred combination of the three accelerators can ensure a long induction period for the rubber compound to flow fully within the mold cavity during vulcanization, thereby enhancing the adhesive reaction.

[0035] Preferably, the antioxidant is one or more of 2,2,4-trimethyl-1,2-dihydroquinoline polymer, N-phenyl-α-aniline, N-phenyl-N'-isopropyl-p-phenylenediamine, and N-N'-diphenyl-p-phenylenediamine. The selected antioxidant has good dynamic protection capabilities and effectively inhibits metal catalysis.

[0036] Preferably, the raw materials also include 40-108 parts of iron oxide, with the ratio of iron oxide to carbon black being 1:1.2-1.5. Iron oxide readily bonds with natural rubber molecular chains, tightly bonding the white carbon black to the natural rubber. When combined with a suitable silane coupling agent, the addition of iron oxide to the system can produce a strong reinforcing effect on the natural rubber.

[0037] The weight ratio of stearic acid to zinc oxide in the mixture is preferably 0.5 to 2:1. Selecting a suitable ratio of stearic acid to zinc oxide can improve the solubility of zinc oxide in rubber, react with the accelerator to form a complex with good solubility in rubber, activate the accelerator and sulfur, continuously form short cross-links during vulcanization, increase the cross-link density, and improve vulcanization efficiency.

[0038] A method for preparing a tire tread rubber for preventing groove bottom cracking comprises the following steps:

[0039] S1 Pre-mixing: natural rubber, solution polymerized styrene-butadiene rubber, styrene-butadiene rubber SBR1502, high-cis BR9000, 2 / 3 of the total carbon black, modified diatomaceous earth, and / or iron oxide are placed in the mixing chamber of an internal mixer at a rotor speed of 25-35 rpm. When the temperature of the rubber compound reaches 86-96°C, the plug is raised for 5 seconds; the plug is pressed, and when the temperature reaches 136-138°C, the plug is raised for 5 seconds; the plug is pressed for the third time, and the rubber compound is mixed until the temperature reaches 163-165°C, and the rubber is discharged to obtain a pre-mixed rubber. The pre-mixed rubber is cooled to room temperature for later use.

[0040] S2 first stage mixing: put the premixed rubber of S1, silane coupling agent, part of tear-resistant resin, modified aramid fiber, tackifying resin, stearic acid, polyethylene glycol, zinc oxide, stearic acid, antioxidant and anti-fatigue agent into the internal mixer for mixing, the rotor speed is 45-60rpm, the plug is lifted and cleaned every 30s, when the temperature reaches 130-140℃, the plug is lifted and pressed again, mixing until the rubber temperature reaches 160-165℃ and the rubber is discharged, the first stage mixed rubber is placed in the room to cool for 4-12h before the second stage mixing;

[0041] S3 second stage mixing: put the first stage mixed rubber of S2 into the internal mixer again, with the rotor speed of 35-45rpm, and lift the plug after 30s, then add 1 / 3 of the total carbon, another part of the anti-tear resin and antioxidant, and rotate at 30-40rpm. When the temperature reaches 120-130℃, lift the plug and then press it. When the rubber temperature reaches 150℃, discharge the rubber, and place the second stage mixed rubber at room temperature to cool for 4h before final mixing;

[0042] S4 final refining: put the second-stage mixed rubber of S3, sulfur and vulcanization accelerator into the internal mixer, and mix automatically for 250 seconds under the conditions of pressure 45N / cm2, temperature 148℃ and speed 35rmp. After lifting and pressing the plug twice, the rubber is discharged and passed through the open mixer. The sheet is passed through the isolation liquid (mainly including stearic acid soap and talcum powder), cooled and stacked to obtain the tread rubber.

[0043] The SiO2 content in the diatomaceous earth is not less than 90%. Diatomaceous earth is an inorganic mineral material with the same main component as white carbon black. Compared with the rubber compound using only white carbon black, the diatomaceous earth has the characteristics of low Mooney viscosity, easy processing, short vulcanization time, excellent physical and mechanical properties, and no pollution, thereby improving production efficiency and reducing production energy consumption. White carbon black itself has strong cohesion, but is difficult to be evenly dispersed in the rubber compound. When mixed in large quantities, it is easy to form gel and increase the Mooney viscosity. The increase in Mooney viscosity will make it difficult to extrude the rubber compound into the tread of the all-terrain tire and deteriorate the processing performance. Diatomaceous earth can promote the uniform dispersion of white carbon black in the rubber, reduce its gelation phenomenon, reduce the Mooney viscosity, significantly improve its processing performance, reduce energy consumption in the rubber compound processing process, and reduce relative costs.

[0044] Tear-resistant resin SL6903 is a phenol-dicyclopentadiene (DCPD) resin modified with an unsaturated olefin compound. It is a mixture of natural rosin and petroleum resin. By adding tear-resistant resin to the rubber system, the tear resistance of the rubber compound can be improved.

[0045] The present invention discloses a tire tread rubber for preventing cracking at the bottom of the tread groove. As a new and improved tire tread rubber formula, the invention addresses the defect of cracking at the bottom of the tread groove of semi-steel radial tires. A new material is designed and developed. The material comprises a mixture of natural rubber, solution-polymerized styrene-butadiene rubber (SBR), styrene-butadiene rubber (SBR1502), and high-cis BR9000. Modified carbon black and a matching silane coupling agent are further used to achieve better dispersion and mixing of the reinforcing material and the rubber. The invention particularly addresses the defect of cracking at the bottom of the tread groove of the tread rubber, overcomes the high load, high heat generation, high deformation at high speed, and high inflation pressure during tire operation, and improves the tire's strength, wear resistance, aging, and other properties.

[0046] The method for preparing a tire tread rubber for preventing groove bottom cracking of the present invention has stable process, is suitable for mass production, and has high economic and social benefits. [Specific implementation method]

[0047] The present invention will be further described below in conjunction with specific embodiments 1-6:

[0048] A tire tread rubber for preventing groove bottom cracking, wherein the preparation method comprises the following steps:

[0049] S1 Pre-mixing: natural rubber, solution polymerized styrene-butadiene rubber, styrene-butadiene rubber SBR1502, high-cis BR9000, 2 / 3 of the total carbon black, modified diatomaceous earth, and / or iron oxide are placed in the mixing chamber of an internal mixer at a rotor speed of 25-35 rpm. When the temperature of the rubber compound reaches 86-96°C, the plug is raised for 5 seconds; the plug is pressed, and when the temperature reaches 136-138°C, the plug is raised for 5 seconds; the plug is pressed for the third time, and the rubber compound is mixed until the temperature reaches 163-165°C, and the rubber is discharged to obtain a pre-mixed rubber. The pre-mixed rubber is cooled to room temperature for later use.

[0050] S2 first stage mixing: put the premixed rubber of S1, silane coupling agent, part of tear-resistant resin, modified aramid fiber, tackifying resin, stearic acid, polyethylene glycol, zinc oxide, stearic acid, antioxidant and anti-fatigue agent into the internal mixer for mixing, the rotor speed is 45-60rpm, the plug is lifted and cleaned every 30s, when the temperature reaches 130-140℃, the plug is lifted and pressed again, mixing until the rubber temperature reaches 160-165℃ and the rubber is discharged, the first stage mixed rubber is placed in the room to cool for 4-12h before the second stage mixing;

[0051] S3 second stage mixing: put the first stage mixed rubber of S2 into the internal mixer again, with the rotor speed of 35-45rpm, and lift the plug after 30s, then add 1 / 3 of the total carbon, another part of the anti-tear resin and antioxidant, and rotate at 30-40rpm. When the temperature reaches 120-130℃, lift the plug and then press it. When the rubber temperature reaches 150℃, discharge the rubber, and place the second stage mixed rubber at room temperature to cool for 4h before final mixing;

[0052] S4 final refining: put the second-stage mixed rubber of S3, sulfur and vulcanization accelerator into the internal mixer, and mix automatically for 250 seconds under the conditions of pressure 45N / cm2, temperature 148℃ and speed 35rmp. After lifting and pressing the plug twice, the rubber is discharged and passed through the open mixer. The sheet is passed through the isolation liquid (mainly including stearic acid soap and talcum powder), cooled and stacked to obtain the tread rubber.

[0053] The group distribution ratio in the method is shown in the following table:

[0054] Table 1: Weight ratio of the components described in Examples 1-6

[0055]

[0056]

[0057] A tire tread rubber for preventing groove bottom cracking is prepared by referring to the method of Example 1:

[0058] Table 2: Preparation of tread rubbers for comparative examples 1-5

[0059]

[0060]

[0061] Test results

[0062] The tire tread rubbers for preventing groove bottom cracking prepared in Examples 1-6 and Comparative Examples 1-5 were subjected to performance tests.

[0063] Table 3: Test results of rubber properties of tire tread rubbers prepared in Examples 1-6

[0064]

[0065]

[0066] Table 4: Comparison: 1-5 Tire tread compound performance test results for preventing groove bottom cracking

[0067]

[0068]

[0069] From the test results in the above table, we can see that:

[0070] When the total proportions of carbon black used in Examples 1 and 3 are similar and the proportions of the anti-fatigue agent KP are different, the physical properties of the tread rubbers obtained therefrom, including tear strength (135.21 and 142.12, respectively), compression heat generation (43.1 and 40.4, respectively), Akron abrasion loss (0.060 and 0.021, respectively), loss factor tanδ0℃ (0.243 and 0.289, respectively) and loss factor tanδ60℃ (0.108 and 0.090, respectively) are all good, and other physical properties do not change much, indicating that when the amount of carbon black used is the same, the more the proportion of the anti-fatigue agent KP used, the more significant the tear resistance, wear resistance, high-temperature dynamic fatigue resistance, heat aging resistance and dynamic ozone aging resistance of the vulcanized rubber, the smaller the compression set and compression heat generation, the lower the rolling resistance, the improved wet skid resistance, and the better the overall physical properties.

[0071] When the total amount of carbon black used in Examples 5 and 6 is different (116 parts and 77 parts respectively), and the amount of anti-fatigue agent KP is the same, the physical properties of the tread rubber obtained in Example 6, including tear strength (138.17 and 169.78 respectively), compression heat generation (44.7 and 41.6 respectively), Akron wear loss (0.047 and 0.021 respectively), loss factor tanδ0℃ (0.241 and 0.278 respectively) and loss factor tanδ60℃ (0.105 and 0.099 respectively) are significantly better than those in Example 5, indicating that when the amount of carbon black used is different and the amount of anti-fatigue agent KP used is the same, the tear resistance, wear resistance, high temperature dynamic fatigue resistance, heat aging resistance and dynamic ozone aging resistance of the vulcanized rubber are significant, the compression permanent deformation and compression heat generation are reduced, the rolling resistance is reduced, the anti-skid performance is improved, and the comprehensive physical properties are better.

[0072] The physical properties of the rubber materials prepared with the tread rubbers obtained in Examples 1, 2, 3, 4, 5 and 6, especially the physical properties of the rubber materials prepared with the tread rubbers obtained in Examples 3, 4 and 6, are as follows: the tear strength (respectively 135.21, 148.36, 142.12, 150.25, 138.17, 169.78), the compression heat generation (respectively 43.1, 45.3, 40.4, 42.5, 44.7, 4 1.6), Akron wear loss (respectively 0.06, 0.072, 0.021, 0.034, 0.047, 0.021), loss factor tanδ0℃ (respectively 0.243, 0.255, 0.289, 0.221, 0.241, 0.278) and loss factor tanδ60℃ (respectively 0.108, 0.110, 0.090, 0.100, 0.105, 0.099). Therefore, the physical properties of the rubber material prepared using the tire tread rubber for preventing groove bottom cracking of the present invention are significantly improved because it has higher tear resistance, wear resistance, high-temperature dynamic fatigue resistance, heat aging resistance and dynamic ozone aging resistance, reduced compression permanent deformation and compression heat generation, reduced rolling resistance, improved anti-skid performance, extended the service life of the tire, and reduced the number of waste tires to be processed; it can reduce rolling resistance, reduce fuel consumption, reduce costs, reduce carbon dioxide emissions, and thus improve the ecological environment.

[0073] The anti-cutting and anti-puncture performance of the tread rubber should be evaluated from the two aspects of crack resistance and crack growth resistance. The crack generation of the tread rubber is largely related to its hardness and tensile strength. Under the same load and air pressure, the greater the hardness and tensile strength of the rubber, the smaller the deformation caused by sharp objects, and the less likely it is to produce cracks. The crack growth resistance of the tread rubber is largely related to its tensile strength and elongation at break. The greater the tensile strength and elongation at break of the rubber, the greater the amount of deformation that can be absorbed, and the better the crack growth resistance. The new material of the present application can enhance the elasticity of the rubber, improve the mechanical properties, and improve the flexing resistance. The flexing times can reach more than 200,000 times. It has excellent wear resistance, ensures good fatigue crack propagation resistance and cut resistance, and effectively improves the problem of cracking at the bottom of the groove of the pattern.

[0074] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A tire tread rubber for preventing groove bottom cracking, characterized in that The composition comprises the following components in parts by weight: 35-75 parts of natural rubber, 10-25 parts of solution-polymerized styrene-butadiene rubber, Styrene butadiene rubber SBR1502 15-35, High-cis BR9000 10-30, 1-3 parts of zinc oxide, 22-55 parts of modified diatomaceous earth, 60-125 parts of carbon black, 1.5-4.5 parts of modified aramid fiber, 1-3.5 parts of stearic acid, 1-4.5 parts of polyethylene glycol, 1-2.5 parts of dispersant, Antiaging agent 2-5.5 parts, 1-2.5 parts of tackifying resin, 1.5-4.0 parts of antioxidant, Anti-fatigue agent 1-3.5, Tear-resistant resin 1-4, 1-5.5 parts of silane coupling agent, 1-3 parts of sulfur, 2-7 parts of vulcanization accelerator; The carbon black is composed of three carbon blacks in the following weight ratios: 15-30 parts of N134 carbon black, 15-45 parts of N220 carbon black, and 25-55 parts of modified white carbon black. The white carbon black is modified with a modifier (3-mercaptopropyl) trimethoxysilane and dried and sintered at a temperature of 650°C to 750°C for 1 to 3 hours. The modified aramid fiber Sul fron3001 is 150D and less than 1.5 mm in length. The aramid fiber is a tear-resistant resin of SL6903, the mass content of the cis structure obtained by polymerizing the high-cis BR9000 with a metal catalyst is more than 97%, and the metal catalyst is a (α-diimine) nickel catalyst, or one of a diethylaluminum chloride-cobalt system and a trialkylaluminum-boron trifluoride-nickel system catalyst; the vulcanization accelerator is composed of three accelerators, including 1-3 parts of N-tert-butyl-2-benzothiazole sulfenamide, 1-1.5 parts of 2-thiolbenzothiazole, and 3-5 parts of N-cyclohexyl-bis(2-mercaptobenzothiazole)sulfenamide; The silane coupling agent is one or more of 2-mercaptoethyltriethoxysilane, 3,3'-bis(diphenylcyclohexyloxysilylpropyl) disulfide, 3,3'-bis(ethyl-di-sec-butoxysilylpropyl) disulfide, 3,3'-bis(propyldiethoxysilylpropyl) disulfide, and 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyl tetrasulfide; The raw materials also include 40-108 parts of iron oxide, and the content of the iron oxide to carbon black is 1:1.2-1.

5.

2. The tire tread rubber for preventing groove bottom cracking according to claim 1, characterized in that: The antioxidant is zinc dimethyl dithiophosphate, zinc isobutyl isooctyl dithiophosphate, or zinc dibutyl dithiophosphate; the tackifying resin is a mixture of two or more of phenolic resin, aromatic resin, hydrocarbon resin, terpene resin, indene resin, and coumarone resin.

3. The tire tread rubber for preventing groove bottom cracking according to claim 1, characterized in that: The antioxidant is one or more of 2,2,4-trimethyl-1,2-dihydroquinoline polymer, N-phenyl-α-aniline, N-phenyl-N'-isopropyl-p-phenylenediamine, and N-N'-diphenyl-p-phenylenediamine.

4. A method for preparing a tire tread rubber for preventing groove bottom cracking according to any one of claims 1 to 3, characterized in that The steps include: S1 Pre-mixing: natural rubber, solution polymerized styrene-butadiene rubber, styrene-butadiene rubber SBR1502, high-cis BR9000, 2 / 3 of the total carbon black, modified diatomaceous earth, and iron oxide are placed in the mixing chamber of an internal mixer at a rotor speed of 25-35 rpm. When the temperature of the rubber compound reaches 86-96°C, the plug is raised for 5 seconds; the plug is pressed, and when the temperature reaches 136-138°C, the plug is raised for 5 seconds; the plug is pressed for the third time, and the rubber compound is mixed until the temperature reaches 163-165°C, and the rubber is discharged to obtain a pre-mixed rubber. The pre-mixed rubber is cooled to room temperature for later use. S2 first stage mixing: put the premixed rubber of S1, silane coupling agent, part of tear-resistant resin, modified aramid fiber, tackifying resin, stearic acid, polyethylene glycol, zinc oxide, stearic acid, antioxidant and anti-fatigue agent into the internal mixer for mixing, the rotor speed is 45-60rpm, the plug is lifted and cleaned every 30s, when the temperature reaches 130-140℃, the plug is lifted and pressed again, mixing until the rubber temperature reaches 160-165℃ and the rubber is discharged, the first stage mixed rubber is placed in the room to cool for 4-12h before the second stage mixing; S3 second stage mixing: put the first stage mixed rubber of S2 into the internal mixer again, with the rotor speed of 35-45rpm, and lift the plug after 30s, then add 1 / 3 of the total carbon, another part of the anti-tear resin and antioxidant, and rotate at 30-40rpm. When the temperature reaches 120-130℃, lift the plug and then press it. When the rubber temperature reaches 150℃, discharge the rubber, and place the second stage mixed rubber at room temperature to cool for 4h before final mixing; S4 final refining: put the second-stage mixed rubber of S3, sulfur and vulcanization accelerator into the internal mixer, and automatically mix for 250 seconds under the conditions of pressure 45N / cm2, temperature 148℃ and speed 35rmp. After lifting and pressing the plug twice, the rubber is discharged and passed through the open mixer to thin the lower sheet, pass through the isolation liquid, which includes stearic acid soap and talcum powder, cool and stack, and then the tread rubber is obtained.

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