Tire carcass rubber material with high aging resistance

Abstract

The invention discloses a tire carcass rubber material with high aging resistance, and relates to the technical field of tires. Comprising the following components in parts by weight: 100 parts of a rubber matrix, 0.3-0.5 part of a peptizer, 55-65 parts of carbon black, 1-2.5 parts of N, N '-di-o-tolyl ethylenediamine, 6-8 parts of zinc oxide, 2-3 parts of an anti-aging agent, 1-2 parts of tackifying resin, 0.5-1 part of cobalt salt, 5.5-7.5 parts of a m-methylene white adhesive system, 4-6 parts of sulfur, 0.5-1.5 parts of a rubber accelerator AS10-40GE and 1-1.5 parts of a sulfenamide accelerator. The high-temperature delayed vulcanization characteristic of the rubber accelerator AS10-40GE and the anti-oxidation-crosslinking dual-function synergistic effect of the N, N '-di-o-tolyl ethylenediamine are utilized to construct a'dynamic stable vulcanization network + multi-level anti-oxidation system', so that the thermo-oxidative aging resistance of the tire body rubber material is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of tires, and in particular to a tire carcass rubber material with high aging resistance. Background Art

[0002] Traditional tire carcass compounds are designed to achieve optimal compatibility with the carcass steel wire, with the core focus being on improving the compound's modulus and adhesion. To achieve this, the formula typically incorporates large amounts of carbon black and vulcanizing agents. Carbon black, as a reinforcing agent, significantly increases the compound's hardness, modulus, and wear resistance; while the vulcanizing agent is responsible for building a three-dimensional cross-linked network, imparting the necessary elasticity and strength. However, while this traditional formulation meets basic requirements, it also exhibits some significant flaws:

[0003] First, there's the issue of vulcanization network stability caused by excessive sulfur. To achieve higher crosslink density and adhesion, excess sulfur is often added to traditional formulations. However, excess sulfur forms excessive polysulfide bonds, which are prone to breaking and reforming at high temperatures, resulting in a decrease in crosslink density, a phenomenon known as "reversion." This unstable vulcanization network is particularly fragile in high-temperature environments, significantly reducing the product's fatigue resistance and accelerating the aging process. During tire operation, the tire carcass is exposed to the harsh environment of high temperature and high-frequency deformation for extended periods of time. Insufficient vulcanization network stability directly impacts the tire's service life and safety.

[0004] Secondly, the shortcomings of the antioxidant protection system. During use, tires are continuously exposed to factors such as oxygen, heat, and light, which cause oxidation reactions in the rubber molecular chains, thereby inducing aging. The antioxidant 4020 (6PPD) commonly used in traditional formulas mainly inhibits oxidation reactions by capturing alkyl free radicals. However, its ability to scavenge peroxyl free radicals is relatively weak. More importantly, the metal ions present inside the tire (such as iron ions in steel wire) will catalyze oxidation reactions and accelerate the aging process. The traditional antioxidant system lacks effective inhibition of the catalytic oxidation effect of metal ions, resulting in a significant reduction in the protective effect.

[0005] In summary, while conventional tire carcass compound formulations meet tire performance requirements to a certain extent, they suffer from issues such as insufficient vulcanization network stability and shortcomings in their antioxidant protection systems, which severely restrict tire performance and service life. These issues urgently need to be addressed to develop tires with superior performance and extended service life. Summary of the Invention

[0006] The technical problem to be solved by the present invention is: to overcome the shortcomings of the existing technology and provide a tire carcass rubber compound with high aging resistance. Through material collaborative design, the aging resistance of the carcass rubber compound is systematically improved, providing an innovative solution for the long-term operation of high-load tires.

[0007] The technical solution of the present invention is:

[0008] The tire carcass rubber material with high aging resistance includes the following components in parts by weight: 100 parts of a rubber matrix, 0.3-0.5 parts of a peptizer, 55-65 parts of carbon black, 1-2.5 parts of N,N'-di-o-tolylethylenediamine, 6-8 parts of zinc oxide, 2-3 parts of an antioxidant, 1-2 parts of a tackifying resin, 0.5-1 parts of a cobalt salt, 5.5-7.5 parts of a m-methyl white bonding system, 4-6 parts of sulfur, 0.5-1.5 parts of a rubber accelerator AS10-40GE, and 1-1.5 parts of a sulfenamide accelerator.

[0009] Among them, the rubber accelerator AS10-40GE contains alkoxysilyl groups in its molecular structure, with an active temperature range of 135-160°C. It forms a uniform polysulfide cross-linked network by releasing active sulfur in stages, reducing vulcanization reversion.

[0010] N,N'-di-o-tolylethylenediamine is a bifunctional amine compound. Its molecular structure contains two o-tolyl groups and an ethylenediamine skeleton. The o-tolyl group captures free radicals through steric hindrance, and the ethylenediamine skeleton chelates metal ions (such as Zn 2+ 、Cu 2+ ) inhibits catalytic oxidation, while the amine group reacts with the double bond of the rubber chain to form CN cross-linking bonds, stabilizing the cross-linking network.

[0011] Preferably, the rubber matrix is natural rubber.

[0012] Preferably, the peptizer is SJ-103.

[0013] Preferably, the carbon black is N326 carbon black.

[0014] Preferably, the antioxidant is antioxidant 4020.

[0015] Preferably, the tackifying resin is tert-octylphenol-formaldehyde resin, with the brand being 203 resin or SP1068 resin.

[0016] Preferably, the cobalt salt is cobalt decanoate or cobalt boroacylate.

[0017] Preferably, the m-formaldehyde adhesive system consists of resorcinol R-80 and adhesive RA-65.

[0018] Preferably, the sulfur is insoluble sulfur.

[0019] Preferably, the sulfenamide accelerator is accelerator DZ.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This invention addresses the shortcomings of traditional tire carcass rubber compounds under high-load conditions, such as easy reversion of the vulcanization network and weak antioxidant capacity. By combining the synergistic effect of rubber accelerator AS10-40GE and N,N'-di-o-tolylethylenediamine, the tire carcass rubber compound is comprehensively optimized in terms of performance. The high-temperature delayed vulcanization characteristics of rubber accelerator AS10-40GE optimize the uniformity of the vulcanization network, construct a uniform and stable cross-linked network, significantly inhibit vulcanization reversion and enhance dynamic fatigue resistance, significantly improving dynamic stability. N,N'-di-o-tolylethylenediamine constructs a multi-level antioxidant barrier through free radical capture and metal ion chelation, significantly delaying performance degradation caused by thermal oxidative aging. Ultimately, this invention systematically improves the anti-aging properties of the carcass rubber compound through material collaborative design, providing an innovative solution for the long-term operation of high-load tires. DETAILED DESCRIPTION

[0022] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0023] Examples 1-3 and Comparative Examples 1-3

[0024] The tire carcass rubber compound formulations of Examples 1-3 and Comparative Examples 1-3 are shown in Table 1:

[0025] Table 1 Tire carcass rubber compound formulations of Examples 1-3 and Comparative Examples 1-3

[0026]

[0027] The preparation method of the tire carcass rubber material of Examples 1-3 and Comparative Examples 1-3 comprises the following steps:

[0028] S1 one-stage mixing

[0029] 20# standard rubber and peptizer SJ-103 were pre-mixed in an internal mixer for mastication. The obtained masticated natural rubber and 45 parts of N326 carbon black were then mixed in the internal mixer for 35 seconds. Anti-aging agent 4020, zinc oxide, tackifying resin SP1068, and N,N'-di-o-tolylethylenediamine were then added to the internal mixer and mixed at a speed of 34 rpm. The mixture was lifted and pressed every 30 seconds. When the temperature of the rubber material reached 160°C, the rubber was discharged and sheeted. The mixture was then placed at room temperature for 4 hours to obtain a cooled masterbatch.

[0030] S2 two-stage mixing

[0031] The first stage masterbatch of step S1 and the remaining carbon black, cobalt decanoate, and resorcinol R-80 were simultaneously put into an internal mixer and mixed at a speed of 33 rpm. The mixture was lifted and pressed every 30 seconds. When the temperature of the rubber material reached 150°C, the rubber material was discharged and the sheets were removed. The mixture was placed at room temperature for 4 hours to obtain a cooled second stage masterbatch. The second stage masterbatch was then returned to the original state and placed at room temperature for 4 hours to obtain a third stage masterbatch.

[0032] S3 Final Refining

[0033] The three-stage masterbatch from step S2, insoluble sulfur OT-20, accelerator DZ, rubber accelerator AS10-40GE, and adhesive RA-65 were placed in an internal mixer and mixed at a speed of 27 rpm. The mixture was lifted and pressed at intervals of 30 s, 30 s, and 20 s, and the rubber material was discharged and sheeted when the temperature of the rubber material reached 98°C. After cooling, the tire carcass rubber material was obtained.

[0034] The tire carcass rubber materials prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests after high-temperature vulcanization (high-temperature vulcanization conditions: 145°C x 60 min). The test results are shown in Table 2:

[0035] Table 2 Performance test results of tire carcass rubber materials after high temperature vulcanization of Examples 1-3 and Comparative Examples 1-3

[0036] Test items Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Tensile strength / MPa 25.1 25.8 25.6 26.3 26.2 25.9 Elongation at break / % 466 471 451 432 435 446 tensile product 11697 12152 11546 11362 11397 11551 Shore hardness A / degree 72 73 73 75 75 74 10% modulus of elongation / MPa 1.11 1.04 1.16 1.22 1.2 1.13 100% modulus of tensile stress / MPa 4.18 4.01 4.24 4.73 4.52 4.37 Aging retention rate / % 79 74 75 67 72 72 Tear strength after aging / kN / m 75 68 72 63 65 67 Crack growth after aging / mm 21 25 23 29 27 26 60℃tanδ 0.1026 0.1031 0.1029 0.1023 0.1024 0.1029

[0037] Note: Rubber aging conditions: 145℃×48h, anaerobic aging.

[0038] By comparing Example 1 with Comparative Example 1 in Table 2, it can be seen that compared with Comparative Example 1, although the tensile strength of Example 1 to which N,N'-di-o-tolylethylenediamine and rubber accelerator AS10-40GE are added at the same time is slightly lower, the elongation at break is increased, and the tensile product is increased by about 3%, indicating that the destructive strength of the rubber is slightly improved; the Shore hardness and modulus of tensile stress are reduced, the rigidity of the rubber is reduced, and the flexibility is improved, which is conducive to stress dispersion; the aging retention rate is increased from 67% to 79%, an increase of 12%, and the aging resistance of the rubber is significantly improved; the tear strength after aging is increased from 63kN / m to 75kN / m, an increase of about 19%; the crack growth length after aging is reduced from 29mm to 21mm, and the crack propagation resistance is increased by about 28%, and the tear resistance and crack propagation resistance of the rubber are significantly improved; the heat generation performance is basically the same.

[0039] From the comparison between Example 1 and Comparative Examples 2-3, it can be seen that Example 1, in which both N,N'-di-o-tolylethylenediamine and rubber accelerator AS10-40GE are added, has more obvious advantages than Comparative Examples 2-3 in which only one of the materials is added.

[0040] N,N'-di-o-tolylethylenediamine efficiently captures free radicals through the secondary amino group (-NH-) in its molecule, blocking the oxidative chain reaction. The steric hindrance effect generated by the ortho-methyl group inhibits oxygen diffusion (oxygen permeability is reduced by 42%), delaying the process of thermo-oxidative aging. The rubber accelerator AS10-40GE decomposes at 120-160°C to release active sulfur. By dynamically regulating the vulcanization reaction kinetics, it forms a long-chain stable cross-linked network, improving aging resistance. Its flexible sulfur chains can dissipate stress while increasing the cross-link density, achieving a balance between high elasticity and high strength.

[0041] The synergistic effect of the two materials comes from their chemical reaction and physical interpenetrating network construction: in the early stage of vulcanization, N,N'-di-o-tolylethylenediamine preferentially chelates Zn 2+ ions inhibit zinc oxide-catalyzed oxidative side reactions, while its rigid benzene rings form a molecular barrier. During the main vulcanization phase, the alkaline environment generated by the decomposition of rubber accelerator AS10-40GE triggers the protonation of amine compounds, forming dynamic ionic crosslinks and simultaneously precisely releasing sulfur free radicals to build a three-dimensional crosslinked network. These two factors work together to form a rigid and flexible interpenetrating structure: the rigid benzene rings inhibit excessive molecular chain slip, while the flexible polysulfide bonds enhance crack propagation resistance and, through interfacial enhancement, tortuosity the oxygen diffusion path, thereby achieving improved anti-aging and high tear resistance.

Claims

1. A tire carcass rubber compound having high aging resistance, characterized in that: The invention comprises the following components in parts by weight: 100 parts of rubber matrix, 0.3-0.5 parts of peptizer, 55-65 parts of carbon black, 1-2.5 parts of N,N'-di-o-tolylethylenediamine, 6-8 parts of zinc oxide, 2-3 parts of antioxidant, 1-2 parts of tackifying resin, 0.5-1 parts of cobalt salt, 5.5-7.5 parts of m-methyl white adhesive system, 4-6 parts of sulfur, 0.5-1.5 parts of rubber accelerator AS10-40GE, and 1-1.5 parts of sulfenamide accelerator.

2. The tire carcass rubber material with high aging resistance according to claim 1, characterized in that: The rubber matrix is natural rubber.

3. The tire carcass rubber material with high aging resistance according to claim 1, characterized in that: The peptizer is SJ-103.

4. The tire carcass rubber material with high aging resistance according to claim 1, characterized in that: The carbon black is N326 carbon black.

5. The tire carcass rubber material with high aging resistance according to claim 1, characterized in that: The antioxidant is antioxidant 4020.

6. The tire carcass rubber material with high aging resistance according to claim 1, characterized in that: The tackifying resin is tert-octyl phenolic resin.

7. The tire carcass rubber material with high aging resistance according to claim 1, characterized in that: The cobalt salt is cobalt decanoate or cobalt boroacylate.

8. The tire carcass rubber material with high aging resistance according to claim 1, wherein: The m-methyl white adhesive system consists of resorcinol R-80 and adhesive RA-65.

9. The tire carcass rubber material with high aging resistance according to claim 1, characterized in that: The sulfur is insoluble sulfur.

10. The tire carcass rubber material with high aging resistance according to claim 1, characterized in that: The sulfenamide accelerator is accelerator DZ.

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