Tire tread rubber with low rolling resistance and preparation method thereof

Abstract

The invention discloses low-rolling-resistance tire tread rubber and a preparation method thereof, and belongs to the technical field of rubber.The low-rolling-resistance tire tread rubber is prepared by adopting high-strength aging-resistant butadiene styrene rubber and natural rubber as basic rubber, modifying potassium hexatitanate whiskers through gamma-methacryloxypropyltrimethoxysilane, endowing the potassium hexatitanate whiskers with double bonds, and then conducting irradiation to obtain the low-rolling-resistance tire tread rubber. The modified potassium hexatitanate whisker can be stably dispersed in a polymerization network of the high-strength aging-resistant styrene-butadiene rubber, so that the filler dispersion and chain segment movement capability in the rubber is optimized, the rolling resistance is remarkably reduced, and the whole material is endowed with good aging resistance and mechanical strength; according to the modified styrene-butadiene rubber latex disclosed by the invention, by utilizing the characteristics of carbon-carbon double bonds and high-reaction-activity epoxy groups in glycidyl methacrylate, the epoxy groups on glycidyl methacrylate are chemically bonded with amino groups in an anti-aging component p-aminodiphenylamine, so that the relative molecular mass of the anti-aging component is increased, and the carbon-carbon double bonds are introduced; a site is provided for forming a co-vulcanization system through reaction with rubber.

Description

Technical Field

[0001] This invention belongs to the field of rubber technology, specifically a low rolling resistance tire tread compound and its preparation method. Background Technology

[0002] Tires are an essential component of modern automobiles, playing a vital role in load-bearing, traction, and braking. Tires are a typical rubber composite material system. Due to the high strength, excellent physical properties, and adhesive properties of natural rubber, current automotive tire carcass rubber materials typically use all-natural rubber or natural rubber with a small amount of styrene-butadiene rubber, with carbon black as the filler.

[0003] Tires deform continuously during driving, and under alternating loads, heat is generated due to hysteresis losses, causing the internal temperature to rise. This reduces the tire's airtightness and the bonding strength with the carcass material. Simultaneously, increased deformation increases rolling resistance and causes fatigue damage to the natural rubber system, potentially leading to safety accidents. Therefore, reducing tire rolling resistance and dynamic heat rise through material selection and formulation adjustments in rubber composite systems is of significant practical importance.

[0004] Chinese patent application CN108912420A discloses a method for preparing high wear-resistant rubber material for tires. In this method, potassium hexatitanate whiskers and boron nitride can be used as carriers for sulfur to promote the dispersion of sulfur in the rubber matrix, prevent sulfur agglomeration, promote its uniform distribution in the matrix, and improve the mechanical properties of the rubber. However, it is known in this method that there is a strong repulsive force between the potassium hexatitanate whiskers and boron nitride fillers and the rubber interface, which causes the fillers to tend to agglomerate and cannot be effectively dispersed in the rubber, resulting in insufficient mechanical strength of the rubber material. Summary of the Invention

[0005] The purpose of this invention is to provide a low rolling resistance tire tread compound and its preparation method. High-strength, aging-resistant styrene-butadiene rubber and natural rubber are used as the base rubber. Potassium hexatitanate whiskers are modified with γ-methacryloyloxypropyltrimethoxysilane to impart double bonds. Then, irradiation is used to stably disperse the modified potassium hexatitanate whiskers within the polymer network of the high-strength, aging-resistant styrene-butadiene rubber. This optimizes the dispersion of fillers and chain segment movement within the rubber, significantly reducing rolling resistance and imparting good aging resistance and mechanical strength to the overall material.

[0006] The objective of this invention can be achieved through the following technical solutions: A low rolling resistance tire tread compound, comprising the following components by weight: 80-90 parts natural rubber, 40-50 parts high-strength aging-resistant styrene-butadiene rubber, 20-22 parts carbon black N330, 5-7 parts silane coupling agent Si-69, 2-4 parts stearic acid, 3-5 parts zinc oxide, 3-5 parts naphthenic oil, 2-3 parts antioxidant RD, 3-4 parts sulfur, 1.6-1.8 parts accelerator TMTD, and 1.2-1.4 parts accelerator NOBS.

[0007] Furthermore, the specific preparation steps for high-strength, aging-resistant styrene-butadiene rubber are as follows: Step 1: Using liquid polybutadiene and styrene as raw materials, and glycidyl methacrylate as the third functional monomer, modified styrene-butadiene rubber latex is obtained through free radical copolymerization.

[0008] Step 2: Using modified styrene-butadiene rubber latex and p-aminodiphenylamine as raw materials, aging-resistant styrene-butadiene rubber latex is prepared through an amino ring-opening epoxy reaction.

[0009] Step 3: Under irradiation, the aging-resistant styrene-butadiene rubber latex vulcanizes and shrinks to form rubber nanoparticles. The double bonds remaining in the structure can break with the double bonds of modified potassium hexatitanate whiskers and hydroxyethyl methacrylate under irradiation, resulting in high-strength aging-resistant styrene-butadiene rubber.

[0010] Furthermore, the specific preparation steps for modified styrene-butadiene rubber latex are as follows: The pre-emulsion was placed in a reaction vessel and stirred for 10-12 minutes at 30-35℃ and 400-500 r / min. Then potassium persulfate was added and the reaction was continued for 1-2 hours. Glycidyl methacrylate was then added and the reaction was continued for 1 hour. The mixture was then allowed to cool naturally to room temperature to obtain modified styrene-butadiene rubber latex.

[0011] Furthermore, the ratio of preemulsion, potassium persulfate, and glycidyl methacrylate is 190-195 mL: 1.4-1.6 g: 3.2-4.4 g.

[0012] Furthermore, the specific preparation steps of the preemulsion are as follows: Liquid polybutadiene, styrene, alkylphenol polyoxyethylene ether, and sodium dodecyl sulfate were added to a reaction vessel and stirred at 50-60℃ and 400-500 r / min for 20-30 min. Then, a 10-12% trisodium phosphate solution was added to adjust the pH to 8-9, and stirring was continued for 30-40 min. The product was then placed in ice water at 0℃ and ultrasonically dispersed for 30-40 min to obtain a pre-emulsion.

[0013] Furthermore, the ratio of liquid polybutadiene, styrene, alkylphenol polyoxyethylene ether, sodium dodecyl sulfate and trisodium phosphate solution is 160-170g: 120-122g: 11.5-11.7g: 1.4-1.6g: 30-40mL.

[0014] Furthermore, the specific preparation steps for aging-resistant styrene-butadiene rubber latex are as follows: p-Aminodiphenylamine and modified styrene-butadiene rubber latex were added to a reaction vessel at a ratio of 50-60g:180-190mL. The mixture was stirred at 50-60℃ and 400r / min for 20-30min. Then, under a nitrogen atmosphere, the mixture was stirred for 2-4h and allowed to cool naturally to room temperature to obtain aging-resistant styrene-butadiene rubber latex.

[0015] Furthermore, the specific preparation steps for modified potassium hexatitanate whiskers are as follows: Ethanol and deionized water were added to a reaction vessel and stirred for 20-30 min at 50-60℃ and 400 r / min. The pH was then adjusted to 4-5 with acetic acid, followed by the addition of γ-methacryloyloxypropyltrimethoxysilane. Stirring was continued for 1-2 h, followed by the addition of potassium hexatitanate whiskers. The mixture was ultrasonically dispersed for 40-60 min, allowed to stand naturally for 30-40 min, filtered, and the product was washed 2-4 times with deionized water and vacuum dried at 120-130℃ for 1-2 h to obtain modified potassium hexatitanate whiskers.

[0016] Furthermore, the ratio of ethanol, deionized water, γ-methacryloyloxypropyltrimethoxysilane and potassium hexatitanate whiskers is 900-1000mL:100-120mL:30-40g:100-120g.

[0017] Furthermore, the specific preparation steps for high-strength, aging-resistant styrene-butadiene rubber are as follows: Aging-resistant styrene-butadiene rubber latex, modified potassium hexatitanate whiskers, and hydroxyethyl methacrylate were stirred and mixed, then irradiated at an irradiation dose of 10-12 kGy for 4-6 hours. After filtration, the product was washed 2-4 times with deionized water and vacuum dried at 40-50℃ for 1-2 hours to obtain high-strength aging-resistant styrene-butadiene rubber.

[0018] Furthermore, the ratio of aging-resistant styrene-butadiene rubber latex, modified potassium hexatitanate whiskers, and hydroxyethyl methacrylate is 70-80g: 3-5g: 4-8g.

[0019] The beneficial effects of this invention are: 1. The low rolling resistance tire tread compound prepared by this invention uses high-strength, aging-resistant styrene-butadiene rubber and natural rubber as the base rubber. Potassium hexatitanate whiskers are modified with γ-methacryloyloxypropyltrimethoxysilane to impart double bonds. Then, irradiation is used to enable the modified potassium hexatitanate whiskers to be stably dispersed in the polymer network of high-strength, aging-resistant styrene-butadiene rubber, which optimizes the dispersion of fillers and chain segment movement within the rubber, significantly reduces rolling resistance, and gives the overall material good aging resistance and mechanical strength.

[0020] 2. The modified styrene-butadiene rubber latex of the present invention utilizes the carbon-carbon double bonds and highly reactive epoxy groups present in glycidyl methacrylate. Through chemical bonding between the epoxy groups and the amino groups in the antioxidant p-aminodiphenylamine, the relative molecular mass of the antioxidant component is increased, while the active functional group carbon-carbon double bonds are introduced. This provides possible sites for the reaction with rubber to form a co-vulcanization system, significantly improving the aging resistance of low rolling resistance tire tread rubber and extending the service life of the tire tread. Furthermore, after modification with p-aminodiphenylamine, the scorch time and positive vulcanization time of the styrene-butadiene rubber latex can be shortened, the minimum and maximum torques during vulcanization can be reduced, the crosslinking density can be decreased, and the elongation at break of the vulcanized rubber can be increased.

[0021] 3. The high-strength, aging-resistant styrene-butadiene rubber of the present invention has an amino group structure endowed by p-aminodiphenylamine, which can play an anti-aging role. Furthermore, hydroxyethyl methacrylate endows it with a hydroxyl group. The presence of both hydroxyl and weakly basic amino group structures is similar to the structure of highly active alkanolamine surfactants. Therefore, it can play a similar activating role to alkanolamine surfactants, releasing the accelerators TMTD and NOBS from the state of being adsorbed by the filler. This improves the affinity between the filler and the rubber, reduces the interaction between the filler and the accelerator, allows the accelerator to fully exert its role, activates the vulcanization system, and enables the vulcanization reaction to proceed as early as possible. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1: A method for preparing a low rolling resistance tire tread compound, comprising the following steps: S1: 160g of liquid polybutadiene, 120g of styrene, 11.5g of alkylphenol polyoxyethylene ether and 1.4g of sodium dodecyl sulfate were added to a reaction vessel and stirred for 20min at 50℃ and 400r / min. Then, 30mL of 10% trisodium phosphate solution was added to adjust the pH to 8, and stirring was continued for 30min. The product was placed in ice water at 0℃ and ultrasonically dispersed for 30min to obtain a pre-emulsion. 190mL of the pre-emulsion was placed in a reaction vessel and stirred for 10min at 30℃ and 400r / min. Then, 1.4g of potassium persulfate was added and stirring was continued for 1h. Then, 3.2g of glycidyl methacrylate was added and stirring was continued for 1h. The mixture was then naturally cooled to room temperature to obtain modified styrene-butadiene rubber latex.

[0024] S2: Add 50g of p-aminodiphenylamine and 180mL of modified styrene-butadiene rubber latex to a reaction vessel, stir for 20min at 50℃ and 400r / min, then continue stirring for 2h under a nitrogen atmosphere, and allow to cool naturally to room temperature to obtain aging-resistant styrene-butadiene rubber latex.

[0025] S3: Add 900 mL of ethanol and 100 mL of deionized water to the reaction vessel, stir for 20 min at 50 °C and 400 r / min, then adjust the pH to 4 with acetic acid, then add 30 g of γ-methacryloxypropyltrimethoxysilane, continue stirring for 1 h, add 100 g of potassium hexatate whiskers with an average diameter of 0.5 μm and an average length of 6 μm, ultrasonically disperse for 40 min, let stand naturally for 30 min, filter, wash the product twice with deionized water, and vacuum dry at 120 °C for 1 h to obtain modified potassium hexatate whiskers.

[0026] S4: Mix 70g of aging-resistant styrene-butadiene rubber latex, 3g of modified potassium hexatitanate whiskers and 4g of hydroxyethyl methacrylate, then irradiate at an irradiation dose of 10kGy for 4h, filter, wash the product twice with deionized water, and vacuum dry at 40℃ for 1h to obtain high-strength aging-resistant styrene-butadiene rubber.

[0027] S5: Place 80g of natural rubber and 40g of high-strength, aging-resistant styrene-butadiene rubber in a two-roll mill for plasticizing at 56℃ for 16 minutes, then pass through a thin pass 3 times to obtain plasticized rubber. Add the plasticized rubber to a mixing mill and mix at 65℃ and 50r / min for 2 minutes. Then add 20g of carbon black N330, 5g of silane coupling agent Si-69, 2g of stearic acid, 3g of zinc oxide, 3g of naphthenic oil, and 2g of antioxidant RD. Mix for 12 minutes and discharge. Allow the material to cool naturally for 10 hours to obtain a mixed rubber. Transfer the mixed rubber to a two-roll mill and process at 60℃. Add 3g of sulfur, 1.6g of accelerator TMTD, and 1.2g of accelerator NOBS. Pass through a thin pass 4 times and allow the material to cool naturally for 18 hours to obtain a compound rubber. Vulcanize the compound rubber at 150℃ for 25 minutes to obtain a low rolling resistance tire tread rubber.

[0028] Example 2: A method for preparing a low rolling resistance tire tread compound, comprising the following steps: S1: 165g of liquid polybutadiene, 121g of styrene, 11.6g of alkylphenol polyoxyethylene ether and 1.5g of sodium dodecyl sulfate were added to a reaction vessel and stirred at 55℃ and 450r / min for 25min. Then, 35mL of 11% trisodium phosphate solution was added to adjust the pH to 8.5, and stirring was continued for 35min. The product was placed in ice water at 0℃ and ultrasonically dispersed for 35min to obtain a pre-emulsion. 192.5mL of the pre-emulsion was placed in a reaction vessel and stirred at 32.5℃ and 450r / min for 11min. Then, 1.5g of potassium persulfate was added, and stirring was continued for 1.5h. Then, 3.8g of glycidyl methacrylate was added, and stirring was continued for 1h. The mixture was naturally cooled to room temperature to obtain modified styrene-butadiene rubber latex.

[0029] S2: Add 55g of p-aminodiphenylamine and 185mL of modified styrene-butadiene rubber latex to a reaction vessel, stir for 25min at 55℃ and 400r / min, then continue stirring for 3h under a nitrogen atmosphere, and allow to cool naturally to room temperature to obtain aging-resistant styrene-butadiene rubber latex.

[0030] S3: Add 950 mL of ethanol and 110 mL of deionized water to the reaction vessel and stir for 25 min at 55 °C and 400 r / min. Then adjust the pH value to 4.5 with acetic acid, add 35 g of γ-methacryloxypropyltrimethoxysilane, and continue stirring for 1.5 h. Add 110 g of potassium hexatite whiskers with an average diameter of 0.5 μm and an average length of 6 μm, disperse by ultrasonication for 50 min, let stand naturally for 35 min, filter, wash the product three times with deionized water, and dry under vacuum at 125 °C for 1.5 h to obtain modified potassium hexatite whiskers.

[0031] S4: Mix 75g of aging-resistant styrene-butadiene rubber latex, 4g of modified potassium hexatitanate whiskers and 6g of hydroxyethyl methacrylate, then irradiate at an irradiation dose of 11kGy for 5h, filter, wash the product three times with deionized water, and vacuum dry at 45℃ for 1.5h to obtain high-strength aging-resistant styrene-butadiene rubber.

[0032] S5: Place 85g of natural rubber and 45g of high-strength, aging-resistant styrene-butadiene rubber in a two-roll mill for plasticizing at 57℃ for 17 minutes, then pass through a thin pass 4 times to obtain plasticized rubber. Add the plasticized rubber to a mixing mill and mix at 67.5℃ and 55r / min for 3 minutes. Then add 21g of carbon black N330, 6g of silane coupling agent Si-69, 3g of stearic acid, 4g of zinc oxide, 4g of naphthenic oil, and 2.5g of antioxidant RD. Mix for 13 minutes and discharge. Allow the material to cool naturally for 11 hours to obtain a mixed rubber. Transfer the mixed rubber to a two-roll mill and process at 65℃. Add 3.5g of sulfur, 1.7g of accelerator TMTD, and 1.3g of accelerator NOBS. Pass through a thin pass 5 times and allow the material to cool naturally for 19 hours to obtain a compounded rubber. Vulcanize the compounded rubber at 155℃ for 27.5 minutes to obtain a low rolling resistance tire tread compound.

[0033] Example 3: A method for preparing a low rolling resistance tire tread compound, comprising the following steps: S1: 170g of liquid polybutadiene, 122g of styrene, 11.7g of alkylphenol polyoxyethylene ether and 1.6g of sodium dodecyl sulfate were added to a reaction vessel and stirred at 60℃ and 500r / min for 30min. Then, 40mL of 12% trisodium phosphate solution was added to adjust the pH to 9, and stirring was continued for 40min. The product was placed in ice water at 0℃ and ultrasonically dispersed for 40min to obtain a pre-emulsion. 195mL of the pre-emulsion was placed in a reaction vessel and stirred at 35℃ and 500r / min for 12min. Then, 1.6g of potassium persulfate was added and stirring was continued for 2h. Then, 4.4g of glycidyl methacrylate was added and stirring was continued for 1h. The mixture was naturally cooled to room temperature to obtain modified styrene-butadiene rubber latex.

[0034] S2: Add 60g of p-aminodiphenylamine and 190mL of modified styrene-butadiene rubber latex to a reaction vessel, stir for 30min at 60℃ and 400r / min, then continue stirring for 4h under a nitrogen atmosphere, and allow to cool naturally to room temperature to obtain aging-resistant styrene-butadiene rubber latex.

[0035] S3: Add 1000 mL of ethanol and 120 mL of deionized water to the reaction vessel, stir for 30 min at 60 °C and 400 r / min, then adjust the pH to 5 with acetic acid, then add 40 g of γ-methacryloxypropyltrimethoxysilane, continue stirring for 2 h, add 120 g of potassium hexatate whiskers with an average diameter of 0.5 μm and an average length of 6 μm, ultrasonically disperse for 60 min, let stand naturally for 40 min, filter, wash the product 4 times with deionized water, and vacuum dry at 130 °C for 2 h to obtain modified potassium hexatate whiskers.

[0036] S4: Mix 80g of aging-resistant styrene-butadiene rubber latex, 5g of modified potassium hexatitanate whiskers and 8g of hydroxyethyl methacrylate, then irradiate at an irradiation dose of 12kGy for 6h, filter, wash the product with deionized water 4 times, and vacuum dry at 50℃ for 2h to obtain high-strength aging-resistant styrene-butadiene rubber.

[0037] S5: Place 90g of natural rubber and 50g of high-strength, aging-resistant styrene-butadiene rubber in a two-roll mill for plasticizing at 58℃ for 18 minutes, then pass through a thin pass 5 times to obtain plasticized rubber. Add the plasticized rubber to a mixing mill and mix at 70℃ and 60r / min for 4 minutes. Then add 22g of carbon black N330, 7g of silane coupling agent Si-69, 4g of stearic acid, 5g of zinc oxide, 5g of naphthenic oil, and 3g of antioxidant RD. Mix for 14 minutes and discharge. After discharge, allow to cool naturally for 12 hours to obtain a mixed rubber. Transfer the mixed rubber to a two-roll mill and process at 70℃. Add 4g of sulfur, 1.8g of accelerator TMTD, and 1.4g of accelerator NOBS. Pass through a thin pass 6 times and allow to sheet and cool naturally for 20 hours to obtain a compound rubber. Vulcanize the compound rubber at 160℃ for 30 minutes to obtain a low rolling resistance tire tread rubber.

[0038] Comparative Example 1: Based on Example 3, the aging-resistant styrene-butadiene rubber latex in step S4 was replaced with the modified styrene-butadiene rubber latex prepared in step S1, while the other steps remained unchanged, to prepare a low rolling resistance tire tread compound.

[0039] Comparative Example 2: Based on Example 3, the modified potassium hexatitanate whiskers in step S4 were replaced with the raw potassium hexatitanate whiskers in step S3, while the other steps remained unchanged, to prepare a low rolling resistance tire tread compound.

[0040] Comparative Example 3: Based on Example 3, glycidyl methacrylate in step S1 was omitted, while the remaining steps remained unchanged, to prepare a low rolling resistance tire tread compound.

[0041] In the examples and comparative examples: Liquid polybutadiene, purchased from Shanghai Wandao Chemical Co., Ltd., model: B-1000.

[0042] Alkylphenol polyoxyethylene ether was purchased from Haian Petrochemical Plant in Jiangsu Province, CAS No.: 26636-32-89016-45-9.

[0043] p-Aminodiphenylamine was purchased from Wuhan Jixin Yibang Biotechnology Co., Ltd., CAS No.: 101-54-2.

[0044] Potassium hexatite whiskers were purchased from Hubei Langbowan Biomedical Co., Ltd., CAS No.: 12030-97-6.

[0045] The silane coupling agent Si-69 was purchased from Wuhan Huaxiang Kejie Biotechnology Co., Ltd., CAS No.: 40372-72-3.

[0046] The natural rubber was purchased from Jining Sanshi Biotechnology Co., Ltd., CAS No.: 1623-526-4.

[0047] The naphthenic oil was purchased from Shanghai Hongzhuang Chemical Technology Co., Ltd., CAS No.: 8012-95-1, volatile matter: 6.78%, density: 4.89 g / ml. 3 .

[0048] Performance tests were conducted on Examples 1-3 and Comparative Examples 1-3, and the results are shown in Table 1: 1. According to standard GB / T528-2009, the tensile stress, breaking strength, and elongation at break of the tread rubber for low rolling resistance tires are tested as follows: 50% tensile stress: The tensile stress recorded when the specimen is stretched to 50% elongation, in MPa; Breaking strength: The tensile stress recorded when the specimen is stretched to fracture, in MPa; Elongation at break: The elongation of the specimen at break. According to standard GB / T529-2008, the tear strength of the tread rubber for low rolling resistance tires is tested as follows: Tear strength: The maximum force required to tear the specimen, whether with or without a notch, at a specified speed using a tensile testing machine. The unit of tear strength is kN / m. Higher tear strength indicates better tear resistance of the rubber.

[0049] 2. Shore hardness test: The Shore hardness of the low rolling resistance tire tread compound is evaluated according to the standard GB / T 531.1-2008. The higher the hardness value, the higher the rigidity of the rubber composition.

[0050] 3. DIN Abrasion Index: The abrasion index of low rolling resistance tire tread rubber is tested according to standard GB / T9867-2008. It is calculated as the ratio of the volumetric abrasion of the reference rubber to that of the test rubber, under the same specified test conditions, resulting in a fixed mass loss due to abrasion by abrasive cloth. It is usually expressed as a percentage. A lower abrasion index indicates poorer abrasion resistance.

[0051] 4. Resilience Test: The resilience of vulcanized rubber is tested according to standard GB / T1681-2009. A pendulum device consisting of a pendulum rod and a hemispherical pendulum is used. The pendulum moves freely along an arc-shaped track in a horizontal position, impacting a clamped but freely convex flat sample. The rebound angle is measured with a ruler. The rebound angle indicates the resilience. A larger rebound angle indicates better resilience.

[0052] 5. Dynamic Mechanical Properties: The dynamic mechanical properties of rubber are tested using a DMA (Dynamic Thermomechanical Analyzer). A standard sample is subjected to a specific shear force over a wide frequency and temperature range for continuous testing to obtain the frequency or temperature spectrum of the material's dynamic mechanical properties. During DMA measurement, a sinusoidal mechanical stress is applied to the sample, allowing measurement of the force amplitude, displacement amplitude, and phase shift. The thermal effect based on changes in modulus or damping behavior is determined, and the loss angle Tanδ characterizes the dynamic properties of the rubber. A smaller Tanδ indicates better elasticity and lower heat generation. Tanδ at 0°C characterizes wet grip, while Tanδ at 60°C characterizes rolling resistance.

[0053] 6. Compression Heat Generation: The compression heat generation of vulcanized rubber is tested according to the standard ASTM 623-07. In a constant temperature test chamber, the vulcanized rubber sample is compressed with a certain load, stroke and frequency. The compression heat generation performance of the vulcanized rubber is characterized by the bottom temperature rise, the middle final temperature and permanent deformation. The higher the bottom temperature rise, the higher the middle final temperature, and the greater the permanent deformation, the greater the deformation of the rubber.

[0054] Table 1 project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Tensile strength (MPa) 28.0 28.9 29.5 22.3 20.7 23.6 Elongation at break (%) 530 541 548 445 412 468 Tear strength (kN / m) 82 85 87 64 59 68 Shore hardness A (degrees) 68 67 67 71 73 70 Wear index (%) 180 186 191 142 127 151 Resilience (%) 52 53 54 45 41 47 Tanδ 0.112 0.109 0.106 0.147 0.162 0.138 Bottom temperature rise (°C) 27 26 25 34 39 32 Final temperature in the middle section (°C) 129.6 127.3 125.1 142.8 148.5 139.2 Permanent deformation (%) 1.62 1.54 1.47 2.38 2.71 2.15 As shown in Table 1, in Comparative Example 1, when the aging-resistant styrene-butadiene rubber latex was replaced with modified styrene-butadiene rubber latex without grafting p-aminodiphenylamine, the system lacked the synergistic structure of hydroxyl and weakly basic amine groups. This prevented the competitive adsorption of the amine-like surfactants. Accelerators TMTD and NOBS were largely adsorbed and bound by carbon black and potassium hexatitanate whiskers, failing to fully activate the vulcanization system. The vulcanization reaction was delayed, and the crosslinking network was uneven, leading to a significant decrease in tensile strength, tear strength, and elongation at break, and a significant reduction in resilience. Insufficient vulcanization resulted in a significant increase in hysteresis loss, a marked increase in Tanδ, and an increase in rolling resistance. During tire operation, the bottom temperature rise and the final temperature in the middle were significantly increased, resulting in severe heat generation. Without the anti-aging effect of the amine structure, the aging resistance of the rubber compound deteriorated, the abrasion index decreased, and the hardness was too high.

[0055] In Comparative Example 2, the original whiskers were severely agglomerated in the rubber matrix, with extremely weak interfacial bonding, which easily led to interfacial debonding and stress concentration, directly causing a significant deterioration in tensile strength and tear strength, and a sharp drop in elongation at break. Whisker agglomeration disrupted the uniformity of chain segment movement within the rubber, significantly increasing hysteresis loss, Tanδ, rolling resistance, and internal temperature rise, which easily triggered thermal aging and fatigue damage of the rubber compound. Uneven filler dispersion significantly reduced the wear resistance of the rubber compound, significantly decreased the abrasion index, worsened resilience, and increased permanent deformation, making it unable to meet the requirements for low rolling resistance and high strength tread rubber.

[0056] In Comparative Example 3, p-aminodiphenylamine cannot be chemically bonded and is only present in the form of physical blending. It is prone to migration, blooming and volatilization loss, resulting in a significant decrease in aging resistance and a significant shortening of tire tread service life. The lack of active double bonds and crosslinking sites reduces the regularity of the rubber crosslinking network, worsens vulcanization efficiency, significantly reduces mechanical properties and abrasion performance, and lacks a synergistic functionalized structure, making it impossible to achieve effective release of accelerators and activation of the vulcanization system. This leads to increased hysteresis loss of the rubber compound, increased Tanδ, increased rolling resistance, and significantly worse internal temperature rise and permanent deformation compared to the examples.

[0057] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A low rolling resistance tire tread compound, comprising the following components by weight: 80-90 parts natural rubber, 40-50 parts high-strength aging-resistant styrene-butadiene rubber, 20-22 parts carbon black N330, 5-7 parts silane coupling agent Si-69, 2-4 parts stearic acid, 3-5 parts zinc oxide, 3-5 parts naphthenic oil, 2-3 parts antioxidant RD, 3-4 parts sulfur, 1.6-1.8 parts accelerator TMTD, and 1.2-1.4 parts accelerator NOBS.

2. The low rolling resistance tire tread compound according to claim 1, characterized in that, The specific preparation steps for the high-strength, aging-resistant styrene-butadiene rubber are as follows: Step 1: Using liquid polybutadiene and styrene as raw materials, and glycidyl methacrylate as the third functional monomer, modified styrene-butadiene rubber latex is obtained through free radical copolymerization. Step 2: Using modified styrene-butadiene rubber latex and p-aminodiphenylamine as raw materials, an aging-resistant styrene-butadiene rubber latex is prepared through an amino ring-opening epoxy reaction. Step 3: Under irradiation, the aging-resistant styrene-butadiene rubber latex vulcanizes and shrinks to form rubber nanoparticles. The double bonds remaining in the structure can break with the double bonds of modified potassium hexatitanate whiskers and hydroxyethyl methacrylate under irradiation, resulting in high-strength aging-resistant styrene-butadiene rubber.

3. The low rolling resistance tire tread compound according to claim 2, characterized in that, The specific preparation steps of the modified styrene-butadiene rubber latex are as follows: The pre-emulsion was placed in a reaction vessel and stirred for 10-12 minutes at 30-35℃ and 400-500 r / min. Then potassium persulfate was added and the reaction was continued for 1-2 hours. Glycidyl methacrylate was then added and the reaction was continued for 1 hour. The mixture was then allowed to cool naturally to room temperature to obtain modified styrene-butadiene rubber latex. The ratio of the preemulsion, potassium persulfate, and glycidyl methacrylate used is 190-195 mL. 1.4-1.6g: 3.2-4.4g.

4. The low rolling resistance tire tread compound according to claim 3, characterized in that, The specific preparation steps of the pre-emulsion are as follows: Liquid polybutadiene, styrene, alkylphenol polyoxyethylene ether, and sodium dodecyl sulfate were added to a reaction vessel and stirred at 50-60℃ and 400-500 r / min for 20-30 min. Then, a 10-12% trisodium phosphate solution was added to adjust the pH to 8-9, and stirring was continued for 30-40 min. The product was then placed in ice water at 0℃ and ultrasonically dispersed for 30-40 min to obtain a pre-emulsion.

5. The low rolling resistance tire tread compound according to claim 2, characterized in that, The ratio of the liquid polybutadiene, styrene, alkylphenol polyoxyethylene ether, sodium dodecyl sulfate and trisodium phosphate solution is 160-170g: 120-122g: 11.5-11.7g: 1.4-1.6g: 30-40mL.

6. The low rolling resistance tire tread compound according to claim 2, characterized in that, The specific preparation steps of the aging-resistant styrene-butadiene rubber latex are as follows: p-Aminodiphenylamine and modified styrene-butadiene rubber latex were added to a reaction vessel at a ratio of 50-60g:180-190mL. The mixture was stirred at 50-60℃ and 400r / min for 20-30min. Then, under a nitrogen atmosphere, the mixture was stirred for 2-4h and allowed to cool naturally to room temperature to obtain aging-resistant styrene-butadiene rubber latex.

7. The low rolling resistance tire tread compound according to claim 2, characterized in that, The specific preparation steps for the modified potassium hexatitanate whiskers are as follows: Ethanol and deionized water were added to a reaction vessel and stirred for 20-30 min at 50-60℃ and 400 r / min. The pH was then adjusted to 4-5 with acetic acid, followed by the addition of γ-methacryloyloxypropyltrimethoxysilane. Stirring was continued for 1-2 h, followed by the addition of potassium hexatitanate whiskers. The mixture was ultrasonically dispersed for 40-60 min, allowed to stand naturally for 30-40 min, filtered, and the product was washed 2-4 times with deionized water and vacuum dried at 120-130℃ for 1-2 h to obtain modified potassium hexatitanate whiskers.

8. The low rolling resistance tire tread compound according to claim 7, characterized in that, The ratio of ethanol, deionized water, γ-methacryloyloxypropyltrimethoxysilane and potassium hexatitanate whiskers is 900-1000mL:100-120mL:30-40g:100-120g.

9. A low rolling resistance tire tread compound according to claim 2, characterized in that, The specific preparation steps for the high-strength, aging-resistant styrene-butadiene rubber are as follows: Aging-resistant styrene-butadiene rubber latex, modified potassium hexatitanate whiskers and hydroxyethyl methacrylate were stirred and mixed, and then irradiated at an irradiation dose of 10-12 kGy for 4-6 h. After filtration, the product was washed with deionized water 2-4 times and vacuum dried at 40-50℃ for 1-2 h to obtain high-strength aging-resistant styrene-butadiene rubber. The ratio of the aging-resistant styrene-butadiene rubber latex, modified potassium hexatitanate whiskers, and hydroxyethyl methacrylate is 70-80g: 3-5g: 4-8g.

10. The method for preparing a low rolling resistance tire tread compound according to claim 1, characterized in that, The specific preparation steps for the low rolling resistance tire tread compound are as follows: Natural rubber and high-strength, aging-resistant styrene-butadiene rubber are plasticized in an open mill at 56-58℃ for 16-18 minutes, then passed through a thin pass 3-5 times to obtain a plasticized rubber compound. The plasticized rubber compound is then added to an internal mixer and mixed at 65-70℃ and 50-60 r / min for 2-4 minutes. Then, carbon black, Si-69, stearic acid, zinc oxide, naphthenic oil, and antioxidants are added and mixed for 12-14 minutes before being discharged. After discharge, the material is allowed to cool naturally for 10-12 hours to obtain an internally mixed rubber compound. The internally mixed rubber compound is then transferred to an open mill, and the processing temperature is controlled at 60-70℃. Sulfur, accelerator TMTD, and accelerator NOBS are added and passed through a thin pass 4-6 times. The material is then sheeted and allowed to cool naturally for 18-20 hours to obtain a compounded rubber compound. The compounded rubber compound is then vulcanized at 150-160℃ for 25-30 minutes to obtain a low rolling resistance tire tread compound.