An ultra-low rolling resistance tread rubber and a method for preparing the same

Abstract

This invention discloses an ultra-low rolling resistance tire tread compound, which comprises, by weight: 8-12 parts natural rubber, 12-18 parts butadiene rubber, 22-28 parts solution-polymerized styrene-butadiene rubber, 20-26 parts silica, 5-10 parts modified silica, 0.8-1.2 parts activator ZnO, 0.2-0.5 parts activator SA, 2-3 parts antioxidant, 2-4 parts super tackifying resin, 3-5 parts modified resin, 1.5-2 parts silane coupling agent, 2-3 parts processing aid, 0.8-1.2 parts vulcanizing agent, 0.8-1.2 parts accelerator NS, and 0.8-1.2 parts accelerator DPG. The solution-polymerized styrene-butadiene rubber has a styrene content of 20%-25% and a vinyl content of 60%-70%, the butadiene rubber has a vinyl content of 11%-15%, the modified silica is ultrafine silica powder, and the modified resin is hydrogenated copolymerized petroleum resin. Through the synergistic effect of a rubber compound system with specific microstructure and double silica, the hysteresis loss of the filler network is significantly reduced, resulting in a Tanδ@60℃ value of 0.059 for the tread rubber and a rolling resistance of 4.9 N / kN for the tire. It also has good physical properties and can effectively improve the driving range of electric vehicles, showing good market application prospects.

Description

Technical Field

[0001] This invention relates to the field of tire rubber technology, and more specifically, to an ultra-low rolling resistance tread compound suitable for electric vehicles and its preparation method. Background Technology

[0002] With the rapid development of the new energy vehicle industry, the market share of pure electric vehicles (EVs) is constantly increasing. Driving range is one of the key factors restricting the development of electric vehicles, and tire rolling resistance directly affects vehicle energy consumption and driving range. Studies have shown that for every 10% reduction in tire rolling resistance, the driving range of an electric vehicle can be increased by approximately 1.5-2%. Therefore, developing ultra-low rolling resistance tires has become an important technological path to improve the driving range of electric vehicles.

[0003] Tire tread compound is a core component affecting rolling resistance. In existing technologies, reducing rolling resistance mainly involves replacing traditional carbon black reinforcement systems with silica reinforcement systems. For example, Chinese patent application CN117924814A discloses a low rolling resistance automotive tire tread compound that uses natural rubber, butadiene rubber BR9000, and solution-polymerized styrene-butadiene rubber SSBR254N as the rubber matrix, combined with silica 7000Gr and a small amount of general-purpose furnace black N500 as reinforcement. This reduces rolling resistance to a certain extent, and its dynamic mechanical performance test shows that the lowest Tanδ@60℃ (rolling resistance characterization value) can reach 0.1210.

[0004] However, with the increasing demands for driving range in electric vehicles, existing low rolling resistance tread compounds still struggle to meet market needs. On one hand, the strong filler-filler interactions in traditional silica formulations result in relatively high hysteresis losses. On the other hand, there is a trade-off between the compatibility of the rubber matrix and fillers, as well as processing performance; often, reducing rolling resistance comes at the expense of processing performance or other physical and mechanical properties. Therefore, developing an ultra-low rolling resistance tread compound that maintains good overall performance is a crucial technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a tread compound with ultra-low rolling resistance, good processing performance and comprehensive physical and mechanical properties, and its preparation method, in order to address the shortcomings of the existing tread compound, which still has high rolling resistance and is difficult to meet the ultra-long driving range requirements of electric vehicles.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: An ultra-low rolling resistance tread compound is provided, which, by weight, comprises: 8-12 parts of natural rubber, 12-18 parts of butadiene rubber, 22-28 parts of solution-polymerized styrene-butadiene rubber, 20-26 parts of silica, 5-10 parts of modified silica, 0.8-1.2 parts of activator ZnO, 0.2-0.5 parts of activator SA, 2-3 parts of antioxidant, 2-4 parts of super tackifying resin, 3-5 parts of modified resin, 1.5-2 parts of silane coupling agent, 2-3 parts of processing aid, 0.8-1.2 parts of vulcanizing agent, 0.8-1.2 parts of accelerator NS, and 0.8-1.2 parts of accelerator DPG.

[0007] The solution-polymerized styrene-butadiene rubber comprises 20%~25% styrene and 60%~70% vinyl content; the butadiene rubber comprises 11%~15% vinyl content; the modified silica is ultrafine silica powder; and the modified resin is hydrogenated copolymerized petroleum resin.

[0008] Preferably, the ratio of natural rubber to solution-polymerized styrene-butadiene rubber is 1:2 to 1:3.

[0009] Preferably, the ratio of natural rubber to butadiene rubber is 1:1 to 1:2.

[0010] Preferably, the ratio of the solution-polymerized styrene-butadiene rubber to the total amount of silica and modified silica is 1:1 to 1:2.

[0011] Preferably, the ratio of silica to modified silica is 4:1 to 6:1.

[0012] Preferably, the natural rubber is SCR10 natural rubber, the butadiene rubber is BR9390 butadiene rubber, the solution-polymerized styrene-butadiene rubber is SSBR2408 solution-polymerized styrene-butadiene rubber, the silica is 7000Gr silica, the modified silica is R320U modified silica, the super tackifying resin is KPT-F1360 super tackifying resin, the modified resin is PR383 modified resin, the silane coupling agent is Si75 silane coupling agent, the processing aid is UF700S processing aid, and the vulcanizing agent is S-325 vulcanizing agent.

[0013] Furthermore, the modified resin PR383 is a hydrogenated copolymer petroleum resin obtained by using a catalyst to hydrogenate the unsaturated double bonds in the polymer chain of petroleum resin, converting unsaturated hydrocarbons into saturated hydrocarbons. This resin has a rigid benzene ring structure and a cyclopentadiene macromolecular structure, and exhibits excellent compatibility with solution-polymerized styrene-butadiene rubber.

[0014] Furthermore, the modified silica R320U is an ultrafine silica powder with a three-dimensional network structure formed by silicon atoms and oxygen atoms through covalent bonds, which has the characteristics of stable chemical properties and uniform particle size distribution.

[0015] The present invention also provides a method for preparing the above-mentioned ultra-low rolling resistance tread compound, comprising the following steps: Step 1: Put natural rubber, butadiene rubber, solution-polymerized styrene-butadiene rubber, silica, modified silica, activator SA, modified resin, silane coupling agent, and accelerator DPG into an internal mixer and mix for 80-120 seconds, controlling the mixing temperature to 90℃-110℃. Step 2: Raise the top bolt and continue mixing for 40-60 seconds, controlling the mixing temperature to rise to 130℃-150℃; Step 3: Remove glue, unpack the film, and cool for 8-12 hours; Step 4: Add the cooled film, activator ZnO, antioxidant, super tackifying resin, processing aid, and accelerator NS into a mixer and mix for 60-90 seconds, controlling the mixing temperature to 90℃-120℃. Step 5: Remove glue, unpack the film, and cool for 6-10 hours; Step 6: Put the cooled rubber sheet and vulcanizing agent into a mixer and mix for 50-80 seconds, controlling the mixing temperature at 100℃-115℃. Step 7: Remove the rubber, extrude the sheet, and cool to obtain ultra-low rolling resistance tire tread rubber.

[0016] Preferably, in the first step, 1 / 3 to 1 / 2 of the total amount of accelerator DPG is added, and in the sixth step, the remaining accelerator DPG is added.

[0017] The functions and selection mechanisms of each component in this invention are explained below: 1. Rubber matrix system Natural rubber (SCR10): Provides good initial strength and processing properties. When used in combination with synthetic rubber, it can improve the processing properties and dynamic fatigue properties of the compound.

[0018] Butadiene rubber (BR9390): High cis-butadiene rubber with a vinyl content of 11%~15% is selected. Appropriate vinyl content can improve the dispersibility of silica in the rubber matrix, reduce the filler network structure, thereby reducing hysteresis loss and rolling resistance. Compared with conventional cis-butadiene rubber BR9000, BR9390 has better filler dispersion and lower heat generation.

[0019] Solution-polymerized styrene-butadiene rubber (SSBR2408): This type of styrene-butadiene rubber uses a styrene content of 20%–25% and a vinyl content of 60%–70%. The higher vinyl content provides appropriate rigidity to the rubber molecular chains, enabling good wet grip (hysteresis loss in the high-temperature zone) while maintaining low rolling resistance (hysteresis loss in the low-temperature zone). By controlling the styrene and vinyl content, the glass transition temperature (Tg) of the rubber can be optimized to a range of -20℃ to -25℃, balancing winter performance and low rolling resistance. Compared to emulsion-polymerized styrene-butadiene rubber, solution-polymerized styrene-butadiene rubber has advantages such as a narrower molecular weight distribution, lower branching degree, and better compatibility with silica.

[0020] The synergistic ratio of the three rubbers—natural rubber to solution-polymerized styrene-butadiene rubber (SBR) controlled at 1:2 to 1:3, and natural rubber to butadiene rubber (BR) controlled at 1:1 to 1:2—can form an optimized rubber network structure, ensuring both good processing performance and extremely low rolling resistance.

[0021] 2. Reinforcing Filling System Silica (7000Gr): Highly dispersible precipitated silica, providing the main reinforcing effect. Its high specific surface area and surface silanol groups can form filler-rubber interactions with rubber molecular chains, improving the strength of the compound.

[0022] Modified silica (R320U): Ultrafine silica powder, composed of silicon and oxygen atoms forming a three-dimensional network structure through covalent bonds. Its particle size is smaller than conventional silica, allowing it to fill the voids in the network formed by 7000Gr silica particles, increasing the packing density of the filler, reducing direct contact and friction between fillers, and thus significantly reducing hysteresis losses in the filler network. Simultaneously, R320U has high surface activity, which is beneficial for its reaction with silane coupling agents, enhancing the filler-rubber interaction.

[0023] Synergistic effect of bis(fumed silica): Blending 7000Gr with R320U in a ratio of 4:1 to 6:1 creates a bimodal filler particle size distribution. Larger-diameter 7000Gr particles form the main reinforcing network, while smaller-diameter R320U particles fill network voids, reducing filler-filler contact points and minimizing energy loss under dynamic conditions. Simultaneously, controlling the total ratio of solution-polymerized styrene-butadiene rubber (SBR) to bis(fumed silica) at 1:1 to 1:2 ensures the filler forms a suitable network structure within the rubber matrix, providing reinforcement without causing excessive rolling resistance due to an overly strong filler network.

[0024] 3. Additive System Silane coupling agent (Si75): bis-[3-(triethoxysilane)propyl]-tetrasulfide, which can react with the silanol groups on the surface of silica during compounding, and simultaneously undergo cross-linking with rubber molecular chains during vulcanization, enhancing filler-rubber interaction and reducing filler-filler interaction. Compared with Si69, Si75 has a moderate sulfur chain length, higher processing safety, and can be compounded at higher temperatures, which is beneficial for silica dispersion.

[0025] Modified resin (PR383): A hydrogenated copolymer petroleum resin. Through hydrogenation, the unsaturated double bonds in the petroleum resin are saturated, improving its thermal stability and compatibility with rubber. The PR383 molecular structure contains both a rigid benzene ring structure and a cyclopentadiene macromolecular structure, exhibiting excellent compatibility with solution-polymerized styrene-butadiene rubber. Under high-speed driving (high-frequency deformation) conditions, the rigid benzene ring structure provides appropriate energy dissipation, maintaining wet grip; under normal driving conditions, it maintains low hysteresis loss, achieving low rolling resistance.

[0026] Super tackifying resin (KPT-F1360): A non-thermally reactive alkylphenol resin that can significantly improve the surface tack of uncured rubber compounds, enhance interlayer adhesion and molding process performance, and ensure good operability of ultra-low rolling resistance formulations in actual production.

[0027] Processing aid (UF700S): Improves the dispersion of silica in rubber, reduces Mooney viscosity of rubber compound, and improves mixing efficiency and extrusion molding performance.

[0028] Vulcanization system: A vulcanization system using sulfur (S-325) in combination with accelerators NS and DPG. DPG, as an auxiliary accelerator, can activate the surface of silica, promote the silanization reaction, and improve the dispersion and vulcanization properties of silica.

[0029] Compared with the prior art, the beneficial effects of the present invention are: This invention, through the selection of solution-polymerized styrene-butadiene rubber and cis-butadiene rubber with specific microstructures, combined with a dual-fumed silica compound system, significantly reduces the hysteresis loss of the filler network structure and the rubber matrix. Dynamic mechanical property tests show that the Tanδ@60℃ value of the tread rubber of this invention can reach as low as 0.059, which is more than 52% lower than the comparative example (0.124) and more than 51% lower than the prior art (the lowest value of 0.1210 in the example of CN117924814A), achieving the technical effect of ultra-low rolling resistance.

[0030] While achieving ultra-low rolling resistance, the tread compound of this invention maintains good physical and mechanical properties. Its 300% tensile stress is comparable to the comparative example, its tear strength is comparable or slightly improved, its hardness is moderate, and it exhibits good abrasion resistance (DIN abrasion index 91%~105%). By controlling the glass transition temperature (Tg) of the rubber to -18.5℃~-23.5℃, the low-temperature dynamic properties of the compound are significantly improved. The E*@-25℃ value (characterized by snow handling performance) is 107~157, far superior to the comparative example's 1503, indicating that the tread compound of this invention has excellent snow handling performance. The addition of the super tackifying resin KPT-F1360 significantly improves the tackiness of the uncured compound, solving the problem of poor interlayer adhesion that may occur in the production of high-performance formulations, and ensuring the practical applicability of the formulation.

[0031] When the tread compound of this invention is used in 225 / 55 R17 101V tires, the rolling resistance tested according to ISO28580 standard can reach as low as 4.9 N / kN, which is 24.6% lower than the comparative example (6.5 N / kN). When applied to electric vehicles, it can significantly improve the driving range and has good economic and social benefits. Detailed Implementation

[0032] The preferred embodiments of the present invention will now be described in detail so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0033] Example 1 Raw material composition (parts by weight): 20 parts natural rubber (SCR10), 30 parts butadiene rubber (BR9390), 50 parts solution-polymerized styrene-butadiene rubber (SSBR2408), 45 parts silica (7000Gr), 10 parts modified silica (R320U), 3.6 parts coupling agent (SI75), 2.8 parts activator (1.9 parts ZNO, 0.9 parts SA), 6.5 parts antioxidant (2.5 parts 6PPD, 2 parts RD, 2 parts 0355), 5 parts super tackifying resin KPT-F1360, 10 parts modified resin (5 parts PR383), 5 parts processing aid (UF700S), 2 parts vulcanizing agent (S-325), 2 parts accelerator (NS), 1.5 parts accelerator (DPG).

[0034] The preparation method includes the following steps: Step 1: Put natural rubber, butadiene rubber, solution-polymerized styrene-butadiene rubber, silica, modified silica, activator SA, modified resin PR383, silane coupling agent Si75, and accelerator DPG (1 / 2 of the total amount) into a 270L internal mixer and mix for 100 seconds, controlling the mixing temperature at 100℃±5℃. Step 2: Raise the top bolt and continue mixing for 50 seconds, controlling the mixing temperature to rise to 140℃±5℃; Step 3: Remove glue, unpack the film, and allow it to cool naturally for 10 hours; Step 4: Put the cooled film, activator ZnO, antioxidant, super tackifying resin KPT-F1360, processing aid UF700S, and accelerator NS into a mixer and mix for 75 seconds, controlling the mixing temperature at 105℃±5℃. Step 5: Remove glue, unpack the film, and allow it to cool naturally for 8 hours; Step 6: Put the cooled rubber sheet, vulcanizing agent S-325, and remaining accelerator DPG into an internal mixer and mix for 65 seconds, controlling the mixing temperature at 110℃±5℃. Step 7: Remove the rubber, extrude the sheet, and cool to obtain ultra-low rolling resistance tire tread rubber.

[0035] Example 2 Raw material composition (parts by weight): 15 parts natural rubber (SCR10), 30 parts butadiene rubber (BR9390), 55 parts solution-polymerized styrene-butadiene rubber (SSBR2408), 50 parts silica (7000Gr), 5 parts modified silica (R320U), 3.6 parts coupling agent (SI75), 2.8 parts activator (1.9 parts ZNO, 0.9 parts SA), 6.5 parts antioxidant (2.5 parts 6PPD, 2 parts RD, 2 parts 0355), 5 parts super tackifying resin KPT-F1360, 10 parts modified resin (5 parts PR383), 5 parts processing aid (UF700S), 2 parts vulcanizing agent (S-325), 2 parts accelerator (NS), 1.5 parts accelerator (DPG).

[0036] The preparation method is the same as in Example 1.

[0037] Example 3 Raw material composition (parts by weight): 25 parts natural rubber (SCR10), 30 parts butadiene rubber (BR9390), 45 parts solution-polymerized styrene-butadiene rubber (SSBR2408), 40 parts silica (7000Gr), 15 parts modified silica (R320U), 3.6 parts coupling agent (SI75), 2.8 parts activator (1.9 parts ZNO, 0.9 parts SA), 6.5 parts antioxidant (2.5 parts 6PPD, 2 parts RD, 2 parts 0355), 5 parts super tackifying resin KPT-F1360, 10 parts modified resin (5 parts PR383), 5 parts processing aid (UF700S), 2 parts vulcanizing agent (S-325), 2 parts accelerator (NS), 1.5 parts accelerator (DPG).

[0038] The preparation method is the same as in Example 1.

[0039] Preparation of the comparative example (pure silica binder): Raw material composition (parts by weight): 10 parts natural rubber (KNR20), 23.4 parts styrene-butadiene rubber (NS522), 73 parts styrene-butadiene rubber (SSBR-2466), 60 parts high-dispersion silica (7000Gr), 5.7 parts processing oil (TDAE), 4 parts coupling agent SI75, 2.8 parts activator (1.9 parts ZNO, 0.9 parts SA), 7.3 parts antioxidant (2.5 parts 6PPD, 0.7 parts 3100, 2 parts RD, 2.1 parts 0355), 2 parts resin HRJ10420, 4.5 parts processing aid UF700S, 1.8 parts vulcanizing agent S-325, 2.2 parts accelerator NS, 1.5 parts accelerator DPG.

[0040] The preparation process adopts the conventional two-stage mixing method for tread rubber.

[0041] Performance Testing and Evaluation The rubber compounds obtained in Examples 1-3 and the comparative examples were subjected to performance tests under the same conditions. The test results are shown in Table 1.

[0042] Table 1 Main Technical Indicators of Rubber Compound Meanwhile, the rubber compounds from each embodiment and comparative example were used to manufacture 225 / 55 R17 101V tires, and rolling resistance tests were conducted according to ISO28580 standard. The test results are shown in Table 2.

[0043] Table 2. Tire rolling resistance test results (225 / 55 R17 101V, ISO28580) The test data in Tables 1 and 2 clearly show that: 1. Rolling Resistance Performance: The tread compound prepared in the embodiments of this invention has a Tanδ@60℃ value (rolling resistance characterization) of 0.059~0.075, which is more than 40%~52% lower than that of the comparative example (0.124). Among them, Example 2 performs best, with a Tanδ@60℃ as low as 0.059, which is 52.4% lower than that of the comparative example. In the corresponding tire rolling resistance test, the tire rolling resistance of Example 2 is as low as 4.9 N / kN, which is 24.6% lower than that of the comparative example (6.5 N / kN), achieving the expected goal of ultra-low rolling resistance.

[0044] 2. Comprehensive physical and mechanical properties: While significantly reducing rolling resistance, the 300% constant elongation stress and tear strength of this embodiment are comparable to or slightly improved compared to the comparative example, and the hardness is increased, which is beneficial to improving the handling stability of the tire. Although the tensile strength and elongation are reduced, they still meet the requirements for tire tread compound use.

[0045] 3. Winter performance: The glass transition temperature (Tg) of the embodiments of the present invention is reduced to -18.5℃ to -23.5℃, which is much lower than the comparative example of -4.4℃. The E*@-25℃ value (characterization of snow handling) is 107~157, which is significantly lower than that of the comparative example (1503), indicating that the tread compound of the present invention has a lower modulus under low temperature conditions, which can better adapt to snow and ice road conditions and provide excellent winter handling performance.

[0046] 4. Wear resistance: The DIN wear index of the embodiment of the present invention is 91%~105%, which is comparable to or slightly improved from the comparative example (90%), indicating that wear resistance is not sacrificed while achieving ultra-low rolling resistance, thus ensuring the service life of the tire.

[0047] 5. Processing performance verification: In actual production, the rubber compound of the present invention containing the super tackifying resin KPT-F1360 showed significantly better surface tack on the uncured rubber than the comparative formulation without the resin. It also exhibited good molding process performance and no interlayer adhesion problems were observed, thus verifying the practical applicability of the formulation.

[0048] Comparative Analysis of Examples: Comparing Examples 1-3, Example 2 achieved the best balance between rolling resistance (Tanδ@60℃=0.059, tire rolling resistance 4.9N / kN) and winter performance (Tg-18.5℃, E*@-25℃=157), while also exhibiting good abrasion resistance (91%) and tear strength (42kN / m). This indicates that the formulation with a natural rubber to solution-polymerized styrene-butadiene rubber ratio of 1:3.67 and a silica to modified silica ratio of 10:1 has advantages in achieving ultra-low rolling resistance.

[0049] In summary, this invention, through the selection of solution-polymerized styrene-butadiene rubber and cis-butadiene rubber with specific microstructures, combined with a dual-fumed silica compound system and optimized additives, has successfully developed a tread compound that combines ultra-low rolling resistance, good winter performance, excellent processability, and comprehensive physical and mechanical properties. Compared with existing technologies, this invention significantly reduces rolling resistance, effectively improving the driving range of electric vehicles, and possesses significant technological value and broad market application prospects.

[0050] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. An ultra-low rolling resistance tire tread compound, characterized in that, By weight, its raw material composition includes: 8-12 parts natural rubber, 12-18 parts butadiene rubber, 22-28 parts solution-polymerized styrene-butadiene rubber, 20-26 parts silica, 5-10 parts modified silica, 0.8-1.2 parts activator ZnO, 0.2-0.5 parts activator SA, 2-3 parts antioxidant, 2-4 parts super tackifying resin, 3-5 parts modified resin, 1.5-2 parts silane coupling agent, 2-3 parts processing aid, 0.8-1.2 parts vulcanizing agent, 0.8-1.2 parts accelerator NS, and 0.8-1.2 parts accelerator DPG; The solution-polymerized styrene-butadiene rubber comprises 20% to 25% styrene content and 60% to 70% vinyl content; The butadiene rubber comprises 11% to 15% vinyl content; The modified silica is ultrafine silica powder; The modified resin is a hydrogenated copolymerized petroleum resin.

2. The ultra-low rolling resistance tread compound according to claim 1, characterized in that, The ratio of natural rubber to solution-polymerized styrene-butadiene rubber is 1:2 to 1:

3.

3. The ultra-low rolling resistance tread compound according to claim 1, characterized in that, The ratio of natural rubber to butadiene rubber is 1:1 to 1:

2.

4. The ultra-low rolling resistance tread compound according to claim 1, characterized in that, The ratio of solution-polymerized styrene-butadiene rubber to total amounts of silica and modified silica is 1:1 to 1:

2.

5. The ultra-low rolling resistance tread compound according to claim 1, characterized in that, The ratio of silica to modified silica is 4:1 to 6:

1.

6. The ultra-low rolling resistance tread compound according to claim 1, characterized in that, The natural rubber is SCR10 natural rubber, the butadiene rubber is BR9390 butadiene rubber, the solution-polymerized styrene-butadiene rubber is SSBR2408 solution-polymerized styrene-butadiene rubber, the silica is 7000Gr silica, the modified silica is R320U modified silica, the super tackifying resin is KPT-F1360 super tackifying resin, the modified resin is PR383 modified resin, the silane coupling agent is Si75 silane coupling agent, the processing aid is UF700S processing aid, and the vulcanizing agent is S-325 vulcanizing agent.

7. The ultra-low rolling resistance tread compound according to claim 1 or 6, characterized in that, The modified resin PR383 is a hydrogenated copolymer petroleum resin obtained by using a catalyst to hydrogenate unsaturated hydrocarbons into saturated hydrocarbons through a hydrogenation reaction between hydrogen and the unsaturated double bonds in the polymer chain of petroleum resin.

8. The ultra-low rolling resistance tread compound according to claim 1 or 6, characterized in that, The modified silica R320U is an ultrafine silica powder with a three-dimensional network structure formed by silicon atoms and oxygen atoms through covalent bonds.

9. A method for preparing an ultra-low rolling resistance tread compound as described in any one of claims 1-8, characterized in that, Includes the following steps: Step 1: Put natural rubber, butadiene rubber, solution-polymerized styrene-butadiene rubber, silica, modified silica, activator SA, modified resin, silane coupling agent, and accelerator DPG into an internal mixer and mix for 80-120 seconds, controlling the mixing temperature to 90℃-110℃. Step 2: Raise the top bolt and continue mixing for 40-60 seconds, controlling the mixing temperature to rise to 130℃-150℃; Step 3: Remove glue, unpack the film, and cool for 8-12 hours; Step 4: Add the cooled film, activator ZnO, antioxidant, super tackifying resin, processing aid, and accelerator NS into a mixer and mix for 60-90 seconds, controlling the mixing temperature to 90℃-120℃. Step 5: Remove glue, unpack the film, and cool for 6-10 hours; Step 6: Put the cooled rubber sheet and vulcanizing agent into a mixer and mix for 50-80 seconds, controlling the mixing temperature at 100℃-115℃. Step 7: Remove the rubber, extrude the sheet, and cool to obtain ultra-low rolling resistance tire tread rubber.

10. The method for preparing the ultra-low rolling resistance tread compound according to claim 9, characterized in that, In the first step, 1 / 3 to 1 / 2 of the total amount of accelerator DPG is added, and in the sixth step, the remaining accelerator DPG is added.

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