High abrasion resistant tread for mining tires and method of making same

Abstract

The application discloses a high-wear-resistance tread rubber for mine tires and a preparation method thereof, and relates to the technical field of tires. The application creatively introduces ATT-Si / AL additives, which are used as wear-resistance main bodies together with carbon black, and first applies a basic accelerator, formaldehyde-p-toluidine condensate, and a conventional accelerator in a wear-resistance tread rubber system; wherein the accelerator, formaldehyde-p-toluidine condensate, not only provides flat curing characteristics and excellent aging resistance for the rubber compound, but also solves the problems of "filler-rubber" interface weakening and stress concentration caused by high-hardness fillers by activating silanization reaction and catalyzing covalent bonding between the sulfur crosslinking network and the interface of rigid fillers; the ATT-Si / AL additives and the accelerator, formaldehyde-p-toluidine condensate, are synergistic, forming a "physical-chemical" dual-enhanced network, so that the tread rubber can maintain high strength and high wear resistance under extreme wear.

Description

Technical Field

[0001] This invention relates to the field of tire technology, and more specifically to a high wear-resistant tread compound for mining tires and its preparation method. Background Technology

[0002] As a core load-bearing component in harsh working conditions such as mining and material transportation, mining tires must withstand multiple severe tests such as high-intensity wear, sharp ore cutting, frequent dynamic stress impact, and high-temperature heat generation. Therefore, high wear resistance, excellent anti-cutting and anti-chipping properties, good mechanical strength, and heat aging stability have become the core requirements for tread compound formulation design.

[0003] In existing technologies, the mainstream solutions for improving the wear resistance of mining tire tread compounds mainly focus on "filler reinforcement," which includes two approaches: one is to significantly increase the amount of carbon black filler (usually exceeding 60 parts), utilizing the high specific surface area and reinforcing properties of carbon black to improve the hardness and wear resistance of the compound; the other is to add hard inorganic particles such as silicon carbide and alumina to the compound, resisting ore scratches through physical wear-resistant mechanisms. For example, Chinese invention patent CN118812930A discloses a wear-resistant tire tread compound and its preparation method, which adds a composite filler formulated with fillers such as nano-silicon carbide to the tread compound to improve the wear resistance of the tread. However, both solutions have performance bottlenecks that are difficult to overcome: On the one hand, high carbon black filling content will lead to a significant increase in Mooney viscosity of the rubber compound, deterioration of processing fluidity, and at the same time, a decrease in the elasticity of the rubber compound and intense dynamic heat generation. During long-term use, internal heat accumulation can easily lead to accelerated aging, and even risks such as tread delamination and tire blowout. On the other hand, the interfacial compatibility between hard inorganic particles and the rubber matrix is ​​poor. The combination of the two mainly relies on physical adsorption. Under dynamic stress cycling, interfacial slippage and debonding are prone to occur. This not only fails to fully utilize the wear resistance potential of hard particles, but also becomes the core site for crack initiation, resulting in a significant deterioration in the tear resistance and chipping resistance of the rubber compound, which seriously affects the service life of the tire.

[0004] In terms of vulcanization system design, traditional tread rubber formulations often employ a combination of sulfenamide accelerators (such as accelerators CZ and NS) and thiazole accelerators (such as accelerator DM) to balance vulcanization speed and scorch safety. However, this type of system contributes limitedly to "interface strengthening": in multiphase systems composed of fillers with high hardness and high specific surface area, traditional accelerators struggle to regulate the cross-linking reaction at the filler-rubber interface, failing to form a uniform and stable chemically bonded interface. This results in weak interactions dominating the interfacial region, making stress concentration more likely under harsh operating conditions, further exacerbating wear and damage to the rubber compound.

[0005] In summary, existing technologies have significant shortcomings in the synergistic optimization of "filler reinforcement" and "interfacial crosslinking," making it difficult to simultaneously resolve the contradictions between high wear resistance and high toughness, and low heat generation and aging resistance. Therefore, developing a mining tire tread compound that can achieve synergistic effects of physical reinforcement and chemical crosslinking through formulation innovation, while maintaining excellent wear resistance, also taking into account good mechanical properties, processing safety, and aging stability, has become an urgent technical challenge to be solved in this field. Summary of the Invention

[0006] The technical problem to be solved by this invention is to overcome the shortcomings of the prior art, provide a high wear-resistant tread compound for mining tires and its preparation method, creatively introduce ATT-Si / AL additives, and for the first time apply the alkaline accelerator formaldehyde-toluidine condensate and conventional accelerators in synergistic application to the wear-resistant tread compound system. The two work together to form a "physical-chemical" dual reinforcement network, enabling the tread compound to maintain high strength and high wear resistance under extreme wear.

[0007] The technical solution of this invention is as follows:

[0008] On one hand, the present invention provides a high wear-resistant tread compound for mining tires, comprising the following components by weight: 100 parts of rubber matrix, 40-60 parts of carbon black, 5-10 parts of silica, 5-15 parts of ATT-Si / AL additive, 1-2 parts of silane coupling agent, 3-5 parts of zinc oxide, 1-3 parts of stearic acid, 5-7 parts of antioxidant, 1-1.5 parts of sulfur, and 2-2.4 parts of composite accelerator; wherein the composite accelerator is composed of 1.2 parts of accelerator CZ and 0.8-1.2 parts of accelerator formaldehyde-p-toluidine condensate, wherein accelerator CZ is the main accelerator and accelerator formaldehyde-p-toluidine condensate is the co-accelerator.

[0009] Preferably, the rubber matrix is ​​composed of 50-70 parts of natural rubber and 30-50 parts of styrene-butadiene rubber.

[0010] Preferably, the carbon black is N220 carbon black.

[0011] Preferably, the silane coupling agent is TESPT (50% effective content of bis-[γ-(triethoxysilyl)propyl]tetrasulfide), and its amount is 20% of the weight of silica.

[0012] Preferably, the antioxidant is a combination of antioxidant 4020, antioxidant RD, and protective wax.

[0013] On the other hand, the present invention provides a method for preparing the above-mentioned high wear-resistant tread compound for mining tires, comprising the following steps:

[0014] S1 First stage mixing: Add rubber matrix, 35 parts carbon black, ATT-Si / AL additive, zinc oxide, stearic acid and antioxidant to a mixer and mix at 41-45 rpm. Lift and press the rubber 3 times, heat to 140-150℃ to discharge the rubber and obtain the first stage masterbatch. Let it cool.

[0015] S2 two-stage mixing: Add the first-stage masterbatch, remaining carbon black, silica and silane coupling agent to the internal mixer and mix at a speed of 34-38 rpm. Lift and press the batch 3 times. Heat to 140-145℃ and hold for 60-90 seconds to carry out the silanization reaction. Discharge the rubber to obtain the second-stage masterbatch, let it cool, and then perform the first-stage return mixing.

[0016] S3 Final Mixing: Add the second-stage masterbatch, sulfur, and compound accelerator after the return to the mixer and mix them at a speed of 23-27 rpm. Lift and press the rubber 3 times, control the mixing temperature below 100℃, and discharge the rubber after mixing for 110-120 seconds to obtain the high wear-resistant tread rubber for mining tires.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] 1. This invention introduces ATT-Si / AL additives with specific surface properties as the core wear-resistant material and creatively employs a composite accelerator composed of accelerator CZ and alkaline accelerator formaldehyde-p-toluidine condensate. Its core advantage lies in achieving a multi-layered synergistic effect: the ATT-Si / AL additive provides extremely high physical wear resistance; while the alkaline accelerator formaldehyde-p-toluidine condensate in the composite accelerator system not only optimizes the overall vulcanization characteristics, but its alkaline environment also significantly activates the reaction between the silane coupling agent and the filler surface, catalyzing the formation of a stronger "filler-silane layer-rubber" covalent bond interface. This synergy of "physical reinforcement" and "chemical bonding" fundamentally overcomes the interface weakening and stress concentration problems caused by high-hardness fillers, thus maintaining high wear resistance while also improving the tread rubber's cut resistance and aging resistance, successfully breaking through the performance bottleneck of existing technologies.

[0019] 2. In this invention, the ATT-Si / AL additive possesses extremely high Mohs hardness, effectively resisting cutting and scratching from sharp ores and providing basic wear resistance. Simultaneously, its good thermal conductivity facilitates heat dissipation within the rubber compound. Formaldehyde-p-toluidine condensate, as an alkaline accelerator, provides flat vulcanization characteristics, improving the processing safety of the rubber compound. The crosslinking network it promotes is more stable, endowing the rubber compound with excellent heat aging resistance. Furthermore, the alkaline environment of the formaldehyde-p-toluidine condensate accelerator activates the reaction between the silane coupling agent and the surface of the ATT-Si / AL additive, establishing stronger chemical bonds between them. This combines the physical wear resistance advantages of ATT-Si / AL with the interfacial strengthening and aging resistance advantages of the formaldehyde-p-toluidine condensate accelerator, creating a synergistic reinforcing effect and improving the overall performance of the rubber compound. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention.

[0021] The sources of the formaldehyde-p-toluidine condensate and ATT-Si / AL additive in the following examples are as follows:

[0022] Formaldehyde-p-toluidine condensate: Bayer AG, Germany;

[0023] ATT-Si / AL additive: Nanjing Tengyi New Material Technology Co., Ltd.

[0024] Examples 1-3 and Comparative Examples 1-3

[0025] The tread compound formulations of Examples 1-3 and Comparative Examples 1-3 are shown in Table 1:

[0026] Table 1. Tread compound formulations for Examples 1-3 and Comparative Examples 1-3

[0027]

[0028] The preparation methods of the tread rubber in Examples 1-3 and Comparative Examples 1-3 include the following steps:

[0029] S1 Stage Mixing: All natural rubber SMR20 and styrene-butadiene rubber SBR1502, 35 parts of N220 carbon black, ATT-Si / AL additive, zinc oxide, stearic acid, antioxidant 4020, antioxidant RD and protective wax are added to a mixer and mixed at 42 rpm. The mixture is lifted and pressed 3 times, heated to 145℃ and discharged to obtain stage 1 masterbatch, which is then left to cool.

[0030] S2 two-stage mixing: Add the first-stage masterbatch, the remaining N220 carbon black, white carbon black and silane coupling agent TESPT into the internal mixer and mix at 35 rpm. Lift and press the agglomerate 3 times, raise the temperature to 143℃ and hold for 75s to carry out the silanization reaction. Discharge the glue to obtain the second-stage masterbatch, let it cool, and then carry out the first-stage return mixing.

[0031] S3 Final Mixing: Add the second-stage masterbatch, sulfur, accelerator CZ, and accelerator formaldehyde-toluidine condensate to the internal mixer and mix at 25 rpm. Lift and press the rubber 3 times, and control the mixing temperature below 100℃. Mix for 115 seconds and discharge the rubber to obtain the tread rubber.

[0032] After vulcanization, the tread rubbers prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests. The test methods are as follows: Mooney viscosity was tested according to GB / T 1232.1-2016 "Determination of Unvulcanized Rubber Using a Disk Shear Viscometer - Part 1: Determination of Mooney Viscosity"; positive vulcanization time t 90 The tests were conducted according to GB / T 16584-1996 "Determination of Vulcanization Properties of Rubber Using a Rotorless Vulcanizing Tester"; the Shore A hardness was tested according to GB / T 531.1-2008 "Test Method for Indentation Hardness of Vulcanized Rubber or Thermoplastic Rubber - Part 1: Shore Hardness Tester Method (Shore Hardness)"; the 300% constant elongation stress, tensile strength, and elongation at break were tested according to GB / T 528-2009 "Determination of Tensile Stress-Strain Properties of Vulcanized Rubber or Thermoplastic Rubber"; the Akron abrasion was tested according to GB / T The abrasion resistance of vulcanized rubber was tested according to GB / T 1689-2014 "Determination of abrasion resistance of vulcanized rubber (using Akron abrasion tester)". The cutting loss was tested using a dynamic cutting tester under the following conditions: load 475g, cutter speed 110rpm, test speed 200rpm, and test time 60min. The aging retention rate was calculated as: (tensile strength after aging × elongation at break after aging) / (tensile strength before aging × elongation at break before aging) × 100%. The test results are shown in Table 2.

[0033] Table 2 Performance test results of tread rubber samples after vulcanization in Examples 1-3 and Comparative Examples 1-3

[0034]

[0035] Note: The sulfidation sample preparation conditions are 145℃×40min, and the aging conditions are 100℃×48h.

[0036] As shown in Table 2, the Mooney viscosity of Example 1 and Comparative Example 1 are basically the same, and the differences in 300% constant tensile stress, tensile strength, and elongation at break are not significant. However, compared with Comparative Example 1, the hardness of Example 1 is significantly increased, the rigidity of the rubber compound is enhanced, the Akron abrasion loss is reduced by about 30.5%, and the cut resistance is improved by about 28%. It shows significant improvements in impact deformation and abrasion resistance. At the same time, the heat aging resistance (aging retention rate) is also slightly improved, but the vulcanization rate is significantly reduced.

[0037] Comparing Example 1 and Comparative Examples 1-3, it can be found that compared with Comparative Example 1, the performance of Comparative Examples 2-3, which added ATT-Si / AL additive or accelerator formaldehyde-p-toluidine condensate alone, was improved. However, the improvement effect was not as obvious as that of Example 1. In addition to the performance improvement, there was also a problem of some performance degradation.

[0038] As a modified ceramic powder, the core mechanism of ATT-Si / AL additive lies in its physical reinforcement and functionalization effect as a rigid inorganic phase in rubber elastomers. With its extremely high Mohs hardness, this additive provides an effective physical barrier when the rubber compound is subjected to cutting by sharp external minerals. After the hard ATT-Si / AL additive particles are uniformly dispersed in the rubber matrix, they form a large number of diffusely distributed "hard reinforcing points" at the microscopic level. These "hard reinforcing points" directly bear and resist the abrasive action of the abrasive, thereby significantly delaying the occurrence of macroscopic wear.

[0039] Formaldehyde-toluidine condensate, as a basic amine accelerator, primarily functions at two levels: vulcanization chemistry and interfacial chemistry. At the vulcanization chemistry level, its basicity effectively modulates the reaction kinetics of the sulfur-accelerator system, favoring the formation of crosslinking bonds with superior thermal stability, thus endowing the vulcanized rubber network with better resistance to heat and oxygen aging. At the interfacial chemistry level, this is its more crucial role: its alkaline environment significantly catalyzes and accelerates the hydrolysis process of silane coupling agents, as well as the condensation reaction between the hydrolysis products and the silanol groups on the surfaces of inorganic fillers such as silica and ATT-Si / AL additives. This catalytic effect greatly enhances the grafting efficiency of silane coupling agents on the filler surface and the density of the silane coupling agent layer, constructing a solid and chemically active interfacial foundation for the reactive bonding of rubber molecular chains with the terminal polysulfide bonds of the silane coupling agent through sulfur bridges during subsequent vulcanization.

[0040] The interaction between ATT-Si / AL additives and formaldehyde-p-toluidine condensates, through both physical reinforcement and chemical bonding, constructs an integrated composite material structure. The introduction of the formaldehyde-p-toluidine condensate plays a decisive role primarily in the interface construction stage. Through a highly efficient catalytic silanization reaction, it in-situ constructs a layer of chemically bonded organic molecules with active sulfur atoms at their ends on the originally chemically inert surface of ATT-Si / AL hard particles. This interface layer fundamentally alters the bonding properties between the filler and the matrix, transforming weak physical adsorption or van der Waals forces into strong chemical bonds dominated by covalent bonds. During the vulcanization stage, this active interface layer becomes a "molecular bridge" connecting the inorganic rigid phase and the organic elastic network. The rubber macromolecular chains bond with the active sulfur atoms at the ends of the interface layer through a sulfur crosslinking reaction, thus enabling the entire three-dimensional crosslinked network to effectively fix the ATT-Si / AL particles. The core of the synergistic effect between ATT-Si / AL additives and formaldehyde-p-toluidine condensates lies in constructing an integrated composite material structure linked by chemical bonds. Formaldehyde-p-toluidine condensate forms a strongly chemically bonded interfacial layer through catalysis, firmly connecting the rigid ATT-Si / AL particles to the rubber matrix. This increases the resistance to particle pull-out during wear, significantly improving its wear resistance and cutting performance. Furthermore, the robust interfacial bonding prevents microcracks caused by interfacial debonding, protecting the integrity of the cross-linked network and contributing to extended fatigue life. The two components complement each other in performance, forming a comprehensive performance balance achieved through the combined action of chemical bonds, rigid structure, and chain segment structure—a balance unattainable by any single component.

Claims

1. A high-wear-resistant tread compound for mining tires, characterized in that, By weight, it comprises the following components: 100 parts rubber matrix, 40-60 parts carbon black, 5-10 parts silica, 5-15 parts ATT-Si / AL additive, 1-2 parts silane coupling agent, 3-5 parts zinc oxide, 1-3 parts stearic acid, 5-7 parts antioxidant, 1-1.5 parts sulfur, and 2-2.4 parts composite accelerator; wherein the composite accelerator is composed of 1.2 parts accelerator CZ and 0.8-1.2 parts accelerator formaldehyde-p-toluidine condensate.

2. The high wear-resistant tread compound for mining tires as described in claim 1, characterized in that, The rubber matrix is ​​composed of 50-70 parts of natural rubber and 30-50 parts of styrene-butadiene rubber.

3. The high wear-resistant tread compound for mining tires as described in claim 1, characterized in that, The carbon black is N220 carbon black.

4. The high wear-resistant tread compound for mining tires as described in claim 1, characterized in that, The silane coupling agent is TESPT, and its dosage is 20% of the weight of silica.

5. The high wear-resistant tread compound for mining tires as described in claim 1, characterized in that, The antioxidant is a combination of antioxidant 4020, antioxidant RD, and protective wax.

6. The method for preparing the high wear-resistant tread compound for mining tires as described in any one of claims 1-5, characterized in that, Includes the following steps: S1 First stage mixing: Add rubber matrix, 35 parts carbon black, ATT-Si / AL additive, zinc oxide, stearic acid and antioxidant to a mixer and mix at 41-45 rpm. Lift and press the rubber 3 times, heat to 140-150℃ to discharge the rubber and obtain the first stage masterbatch. Let it cool. S2 two-stage mixing: Add the first-stage masterbatch, remaining carbon black, silica and silane coupling agent to the internal mixer and mix at a speed of 34-38 rpm. Lift and press the batch 3 times. Heat to 140-145℃ and hold for 60-90 seconds to carry out the silanization reaction. Discharge the rubber to obtain the second-stage masterbatch, let it cool, and then perform the first-stage return mixing. S3 Final Mixing: Add the second-stage masterbatch, sulfur, and compound accelerator after the return to the mixer and mix them at a speed of 23-27 rpm. Lift and press the rubber 3 times, control the mixing temperature below 100℃, and discharge the rubber after mixing for 110-120 seconds to obtain the high wear-resistant tread rubber for mining tires.

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