A kind of all-steel radial tire bead seat wear-resistant glue and its preparation method

Abstract

This invention provides a wear-resistant rubber for the bead of all-steel radial tires, comprising the following raw materials by weight: 30-70 parts natural rubber, 30-70 parts butadiene rubber, 10-30 parts methyl vinyl silicone rubber, 50-85 parts carbon black, 10-35 parts precipitated silica, silane coupling agent Si69, 3.0-5.0 parts zinc oxide, 1.0-3.0 parts stearic acid, 1.5-2.8 parts sulfur, 0.8-2.0 parts sulfenamide accelerator, 1.0-4.5 parts antioxidant system, 1.0-3.0 parts tackifying resin, 0.5-1.5 parts rubber dispersant, and 2.0-5.0 parts environmentally friendly aromatic oil. This invention uses natural rubber, butadiene rubber, and methyl vinyl silicone rubber to construct a ternary raw rubber system, combined with a composite reinforcing system of HAF carbon black and precipitated silica, as well as corresponding anti-aging and vulcanization systems, which greatly improves the aging performance and flexural fatigue resistance of the rubber compound. At the same time, it avoids the environmental pollution problems caused by the large amount of by-products generated by traditional anti-aging systems, thus improving the environmental performance of the rubber compound.

Description

Technical Field

[0001] This invention relates to the field of rubber material preparation technology, and in particular to a wear-resistant rubber for the bead of an all-steel radial tire and its preparation method. Background Technology

[0002] All-steel radial truck tires are widely used in heavy-duty transport equipment such as freight trucks and engineering vehicles. The bead area is the core stress area, which is subjected to heavy load compression, road friction impact, driving heat and repeated flexural deformation for a long time. It is prone to wear, surface cracking, aging failure, delamination and other failures, which directly shorten the tire's service life and affect the vehicle's driving safety.

[0003] Currently, the industry's traditional bead-resistant rubber generally adopts a binary system of natural rubber and butadiene rubber, relying on high additions of antioxidant 4020 (6PPD) to improve the aging resistance and ozone resistance of the rubber compound, and delay bead cracking. However, with the tightening of global environmental regulations on rubber products and strict restrictions on the emission of 6PPD and its oxidative degradation products in tires, the traditional formulations with high dosages of antioxidant 4020 cannot meet overseas export environmental standards; in addition, the degradation products of tires containing antioxidant 4020 pose potential ecological hazards, and the industry urgently needs to develop formulation solutions that can reduce or even completely replace antioxidant 4020.

[0004] Meanwhile, traditional binary rubber systems have poor heat resistance; during long-distance driving, continuous heat accumulation at the bead joint accelerates the breakage of rubber molecular chains, further exacerbating aging and failure. While silicone rubber possesses excellent resistance to high and low temperatures, oxygen, and ozone aging, its poor compatibility with diene rubbers leads to phase separation during mixing, making it difficult to meet mechanical strength and abrasion resistance standards. Therefore, it has not yet been used in tire structural rubber compounds. Thus, developing a bead-resistant abrasion-resistant rubber that balances environmental friendliness, aging resistance, and mechanical abrasion resistance is a pressing technical challenge in this field.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] To address the aforementioned problems in the prior art, this invention provides a wear-resistant rubber for the bead of all-steel radial tires and its preparation method. It employs a ternary raw rubber system constructed from natural rubber, butadiene rubber, and methyl vinyl silicone rubber (vinyl content 0.1%–0.5%), combined with a HAF carbon black and precipitated silica composite reinforcement system, along with appropriate anti-aging and vulcanization systems. This significantly improves the aging performance and bead wear resistance of the rubber compound, while avoiding the environmental pollution problems caused by the large amount of byproducts generated by traditional anti-aging systems, thus enhancing the green and environmentally friendly performance of the rubber compound.

[0007] The specific details of the technical solution provided by this invention are as follows: On one hand, this invention discloses a wear-resistant rubber for the bead of an all-steel radial tire, comprising the following raw materials by weight: Natural rubber 30-70 parts, butadiene rubber 30-70 parts, methyl vinyl silicone rubber 10-30 parts, carbon black 50-85 parts, precipitated silica 10-35 parts, silane coupling agent 0.3-2.8 parts, zinc oxide 3.0-5.0 parts, stearic acid 1.0-3.0 parts, sulfur 1.5-2.8 parts, sulfenamide accelerator 0.8-2.0 parts, anti-aging system 1.0-4.5 parts, tackifying resin 1.0-3.0 parts, rubber dispersant 0.5-1.5 parts, environmentally friendly aromatic oil 2.0-5.0 parts.

[0008] In some embodiments of this application, the anti-aging system includes antioxidant 4020, antioxidant RD, and microcrystalline wax, wherein the amount of antioxidant 4020 added is 0 to 1.0 parts, the amount of antioxidant RD added is 0.5 to 2.0 parts, and the amount of microcrystalline wax is 0.5 to 1.5 parts.

[0009] In some embodiments of this application, the silane coupling agent is silane coupling agent Si69, and the amount of silane coupling agent Si69 added is 3% to 8% of the mass of precipitated silica.

[0010] In some embodiments of this application, the physicochemical properties of carbon black are as follows: iodine absorption value (82±7) g / kg, DBP oil absorption value (1.02±0.07) cm³ / g, and nitrogen adsorption specific surface area (71~85)×10⁻⁶. 3 m² / kg; Physicochemical properties of precipitated silica: nitrogen adsorption specific surface area (120~160)×10³m² / kg, pH value 6.0~7.5, and loss on heating ≤6.0%.

[0011] In some embodiments of this application, the vinyl content in the methyl vinyl silicone rubber is 0.1% to 0.5%.

[0012] In some embodiments of this application, when the amount of methyl vinyl silicone rubber added is greater than 20 parts, the amount of carbon black N330 is increased by 5 to 10 parts, and the amount of sulfur is increased by 0.2 to 0.5 parts simultaneously.

[0013] On the other hand, the present invention also discloses a method for preparing wear-resistant rubber for the bead of an all-steel radial tire, comprising the following steps: S1, First stage of intensive mixing: Methyl vinyl silicone rubber, precipitated silica, silane coupling agent, zinc oxide, stearic acid, and microcrystalline wax are put into an intensive mixer and mixed at the first intensive mixing temperature for the first intensive mixing time to complete the premixed interface modification. S2, Second-stage mixing: Add natural rubber, butadiene rubber, carbon black N330, tackifying resin, environmentally friendly aromatic oil, rubber dispersant and anti-aging system into the mixing mill, control the temperature and mixing time at the second mixing temperature, and then discharge and cool. S3. Final mixing: Cooled rubber compound is fed into the final mixer, sulfur and sulfenamide accelerators are added, and the mixture is mixed at the final mixing temperature for a preset time, then the rubber is extruded and pressed into sheets. S4. Molding and vulcanization: The rubber sheet obtained in step S3 is used to prepare the bead wear-resistant rubber, which is then bonded to the bead position of the all-steel radial tire and the finished tire is obtained under preset vulcanization conditions.

[0014] In some embodiments of this application, the first mixing temperature is 140°C. o C~150 o C, the first intensive mixing time is 4~6 minutes; The second refining temperature is 130. o C~140 o C. The second refining time is 3-5 minutes.

[0015] In some embodiments of this application, the final refining temperature is 90°C. o C~100 o C. The preset mixing time is 1.5~3 minutes.

[0016] In some embodiments of this application, the preset vulcanization conditions include: a vulcanization temperature of 145°C. o C~155 o C. Vulcanization pressure: 2.5MPa~3.0MPa; Vulcanization time: 40min~50min.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects: (1) It adopts a ternary structure of natural rubber, butadiene rubber and methyl vinyl silicone rubber. Relying on the inherent properties of silicone rubber itself, such as resistance to high and low temperatures, ozone, and humid heat aging, it replaces the aging protection function of antioxidant 4020. The dosage of antioxidant 4020 is reduced from the traditional 3.0~4.0 parts to less than 1.0 parts, which can achieve zero addition and avoid the degradation of this component and pollution of the ecological environment. It meets the environmental protection requirements at home and abroad and is in line with the trend of environmental protection development. (2) Strictly limit the physicochemical parameters of carbon black and precipitated silica to ensure that carbon black provides high strength and wear resistance, and use silica with silane coupling agent to improve interfacial bonding force, make up for the mechanical shortcomings of silicone rubber, and ensure the basic properties of impact resistance, tear resistance and wear resistance of the rubber. (3) A segmented internal mixing process is adopted to complete the high-temperature premixing modification of silicone rubber with silica and silane coupling agent in advance, improve the compatibility of silicone rubber with diene rubber, and avoid problems such as rubber compound separation, rough extrusion surface and uneven vulcanization. (4) Compared with traditional bead wear-resistant rubber formulations, the rubber formulation in this application, under the premise of significantly reducing or even completely eliminating the environmentally restricted antioxidant 4020, has only slight fluctuations in the basic mechanical properties and wear resistance of the rubber compound, which fully meets the bead use standards of all-steel radial tires; the thermo-oxidative aging and ozone aging resistance performance are greatly improved, which can effectively delay the aging and cracking phenomenon of the bead part of the tire during long-term use, extend the service life of the tire, and at the same time successfully avoid the environmental control restrictions related to 6PPD, adapting to the dual market demands at home and abroad. Attached Figure Description

[0018] Figure 1 These are diagrams showing the ozone aging test results of the comparative examples and embodiments of this invention. Figure 2 The diagram shows the Demosia flexural fatigue test results of the comparative examples and embodiments of this invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0020] To address the shortcomings of existing all-steel radial tire bead rubbers, which rely on high-content 6PPD antioxidants, have poor environmental compliance, and weak high-temperature aging resistance, this invention provides an all-steel radial tire bead wear-resistant rubber and its preparation method. By introducing silicone rubber to optimize the raw rubber system and replace the antioxidant's aging resistance function, the invention achieves reduced or no antioxidant 4020 is required. At the same time, it optimizes the reinforcing system indicators and mixing process, taking into account the rubber compound's wear resistance, service stability, environmental friendliness, and processing stability.

[0021] The following describes, but is not limited to, the raw materials used in the embodiments and comparative examples of this application: Raw rubber system: natural rubber, butadiene rubber, methyl vinyl silicone rubber; Reinforcing filler system: carbon black, precipitated silica, silane coupling agent; Vulcanization activation system: zinc oxide, stearic acid; Vulcanization system: sulfur, sulfenamide accelerators; Anti-aging system: Anti-aging agent 4020, anti-aging agent RD, microcrystalline wax; Processing aids: tackifying resins, rubber dispersants, environmentally friendly aromatic oils; Physicochemical properties of carbon black: iodine absorption value (82±7) g / kg, DBP oil absorption value (1.02±0.07) cm³ / g, nitrogen adsorption specific surface area (71~85)×10 3 m² / kg; Physicochemical properties of precipitated silica: nitrogen adsorption specific surface area (120~160)×10³m² / kg, pH value 6.0~7.5, and loss on heating ≤6.0%.

[0022] This invention discloses a method for preparing wear-resistant rubber for the bead of all-steel radial tires, comprising the following steps: S1, First stage of internal mixing: Methyl vinyl silicone rubber, precipitated silica, silane coupling agent Si69, zinc oxide, stearic acid, and microcrystalline wax are put into an internal mixer and mixed at the first internal mixing temperature for the first internal mixing time to complete the premixed interface modification. S2, Second-stage mixing: Add natural rubber, butadiene rubber, carbon black N330, tackifying resin, environmentally friendly aromatic oil, rubber dispersant and anti-aging system into the mixing mill, control the temperature and mixing time at the second mixing temperature, and then discharge and cool. S3. Final mixing: Cooled rubber compound is fed into the final mixer, sulfur and sulfenamide accelerators are added, and the mixture is mixed at the final mixing temperature for a preset time, then the rubber is extruded and pressed into sheets. S4. Molding and vulcanization: The rubber sheet obtained in step S3 is used to prepare the bead wear-resistant rubber, which is then bonded to the bead position of the all-steel radial tire and the finished tire is obtained under preset vulcanization conditions.

[0023] As an example of this application, the first mixing temperature is 140°C. o C~150 o C, the first mixing time is 4-6 minutes; the second mixing temperature is 130 degrees Celsius. o C~140 o C. The second refining time is 3-5 minutes.

[0024] In the above technical solution, the first stage of intensive mixing involves interfacial modification of methyl vinyl silicone rubber and silica, using Si69 coupling agent to improve filler dispersion and enhance the abrasion resistance and interfacial bonding of the rubber compound. During the first stage of intensive mixing, 140~150 o C. Processing conditions of 4-6 minutes ensure sufficient modification and prevent premature degradation of silicone rubber.

[0025] The main rubber system is introduced into the second-stage internal mixing process, and mixed with carbon black and additives, under the second-stage internal mixing conditions of 130~140. o C. Perform controlled mixing for 3-5 minutes to ensure uniform dispersion of fillers, prevent premature scorching of the rubber compound, and stabilize the mechanical and processing properties of the rubber compound.

[0026] As an example of this application, the final refining temperature is 90°C. o C~100 o C. The preset mixing time is 1.5min~3min.

[0027] Through a final refining temperature of 90o C~100 o Mix C for 1.5 to 3 minutes, then add sulfur and accelerator to effectively avoid premature activation of the vulcanization system and ensure the storage stability of the rubber compound and the controllability of subsequent vulcanization.

[0028] As an example of this application, the preset vulcanization conditions include: a vulcanization temperature of 145°C. o C~155 o C. Vulcanization pressure: 2.5MPa~3.0MPa; Vulcanization time: 40min~50min.

[0029] In the above technical solution, the bead wear-resistant rubber is fully cross-linked through molding vulcanization, which significantly enhances the bead's friction resistance and flexural strength, delays bead wear and cracking, and extends the service life of all-steel radial tires.

[0030] Referring to the formulation table of the wear-resistant rubber for all-steel radial tire bead in Table 1 below, unless otherwise specified, the wear-resistant rubber for all-steel radial tire bead in the following examples and comparative examples is prepared using the above method.

[0031] The proportions of each group in Comparative Example 1 and Examples 1-3 are shown in Table 1, and the corresponding test performance of the abrasion-resistant rubber for all-steel radial tire beads is shown in Table 2 below.

[0032] Table 1. Formulation of wear-resistant rubber for bead of all-steel radial tires

[0033] Table 2 Performance Test Data of Bead Wear-Resistant Rubber for All-Steel Radial Tires

[0034] Specifically, the following explanation is based on the formulation table of the wear-resistant rubber for the bead of all-steel radial tires in Table 1 (comparative examples and examples 1-3) and the performance test data table of the wear-resistant rubber for the bead of all-steel radial tires in Table 2 (comparative examples and examples 1-3).

[0035] In the formulation table, antioxidant 4020, antioxidant RD and microcrystalline wax in Examples 1-3 constitute an anti-aging system, wherein the amount of antioxidant 4020 added is 0~1.0 parts, the amount of antioxidant RD added is 0.5~2.0 parts, and the amount of microcrystalline wax is 0.5~1.5 parts.

[0036] In some embodiments of this application, the amount of silane coupling agent Si69 added is 3% to 8% of the mass of precipitated silica.

[0037] In some embodiments of this application, the vinyl content in the methyl vinyl silicone rubber is 0.1% to 0.5%.

[0038] Furthermore, when the amount of methyl vinyl silicone rubber added (parts by mass) is greater than 20 parts, the amount of carbon black N330 is increased by 5 to 10 parts, and the amount of sulfur is increased by 0.2 to 0.5 parts simultaneously.

[0039] Combined with Table 2 and Appendix Figure 1-2 As can be seen from the content shown, the three sets of embodiments of the present invention, compared with the conventional bead wear-resistant rubber formulation of the comparative example, under the premise of significantly reducing or even completely removing the environmentally restricted antioxidant 4020, the basic mechanical properties and wear resistance of the rubber compound only fluctuate slightly, which fully meets the bead use standards of all-steel radial tires.

[0040] The results of ozone aging test and Demosia flexural fatigue test show that the thermo-oxidative aging and ozone aging resistance of the rubber compound in the embodiments of the present invention (especially embodiments 2 and 3) are significantly improved. This can effectively delay the aging and cracking of the tire bead area during long-term use, extend the tire service life, and at the same time successfully avoid the environmental control restrictions related to 6PPD (antioxidant 4020), thus meeting the needs of both domestic and international markets.

[0041] Compared with the prior art, the embodiments proposed in this invention have the following beneficial technical effects: 1) Relying on the natural aging resistance of silicone rubber, the amount of antioxidant 4020 used can be greatly reduced, achieving zero addition and completely avoiding the control risks of California's 6PPD-quinone Act, which is in line with the overseas tire export market and the trend of tire environmental protection development. The rubber compound prepared by the formula in this invention has significantly better resistance to high temperature aging, ozone aging, and flexural aging than traditional formulas, effectively solving the problem of high temperature aging and cracking of heavy truck tires during long-distance driving and extending the service life of the tires. 2) By limiting the physicochemical properties of the reinforcing filler and fine-tuning the formula, the high wear resistance, high tear resistance, and high elastic deformation recovery of the ferrule are ensured, making it suitable for the complex road conditions of heavy-duty vehicles. 3) The overall process of two-stage mixing, final mixing, molding and vulcanization is fully compatible with the existing all-steel radial tire production line, without the need for new equipment or process modification, making production switchover convenient and production costs controllable. 4) The formula is highly adjustable. The ratio of silicone rubber, antioxidant, and reinforcing filler can be flexibly adjusted within a preset range according to market environmental protection requirements, vehicle load rating, and climate conditions of the area of ​​use. It has a wide range of applications.

[0042] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. The implementation schemes in the above embodiments can also be further combined or replaced. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A wear-resistant rubber for the bead of an all-steel radial tire, characterized in that, The preparation materials include the following ingredients in parts by weight: Natural rubber 30-70 parts, butadiene rubber 30-70 parts, methyl vinyl silicone rubber 10-30 parts, carbon black 50-85 parts, precipitated silica 10-35 parts, silane coupling agent 0.3-2.8 parts, zinc oxide 3.0-5.0 parts, stearic acid 1.0-3.0 parts, sulfur 1.5-2.8 parts, sulfenamide accelerator 0.8-2.0 parts, anti-aging system 1.0-7.0 parts, tackifying resin 1.0-3.0 parts, rubber dispersant 0.5-1.5 parts, environmentally friendly aromatic oil 2.0-5.0 parts.

2. The wear-resistant rubber for the bead of an all-steel radial tire according to claim 1, characterized in that, The anti-aging system includes antioxidant 4020, antioxidant RD, and microcrystalline wax, wherein the amount of antioxidant 4020 added is 0 to 1.0 parts, the amount of antioxidant RD added is 0.5 to 2.0 parts, and the amount of microcrystalline wax is 0.5 to 1.5 parts.

3. The wear-resistant rubber for the bead of an all-steel radial tire according to claim 2, characterized in that, The silane coupling agent is silane coupling agent Si69, and its addition amount is 3% to 8% of the mass of precipitated silica.

4. The wear-resistant rubber for the bead of an all-steel radial tire according to any one of claims 1-3, characterized in that, The physicochemical properties of the carbon black are as follows: iodine absorption value (82±7) g / kg, DBP oil absorption value (1.02±0.07) cm³ / g, and nitrogen adsorption specific surface area (71~85)×10⁻⁶. 3 m² / kg; The physicochemical properties of the precipitated silica are: nitrogen adsorption specific surface area (120~160)×10³m² / kg, pH value 6.0~7.5, and loss on heating ≤6.0%.

5. The wear-resistant rubber for the bead of an all-steel radial tire according to claim 4, characterized in that, The vinyl content in the methyl vinyl silicone rubber is 0.1% to 0.5%.

6. The wear-resistant rubber for the bead of an all-steel radial tire according to claim 5, characterized in that, When the amount of methyl vinyl silicone rubber added is greater than 20 parts, the amount of carbon black N330 should be increased by 5 to 10 parts, and the amount of sulfur should be increased by 0.2 to 0.5 parts.

7. A method for preparing the wear-resistant rubber for the bead of an all-steel radial tire according to any one of claims 2-6, characterized in that, Includes the following steps: S1, First stage of intensive mixing: Methyl vinyl silicone rubber, precipitated silica, silane coupling agent, zinc oxide, stearic acid, and microcrystalline wax are put into an intensive mixer and mixed at the first intensive mixing temperature for the first intensive mixing time to complete the premixed interface modification. S2, Second-stage mixing: Add natural rubber, butadiene rubber, carbon black N330, tackifying resin, environmentally friendly aromatic oil, rubber dispersant and anti-aging system into the mixing mill, control the temperature and mixing time at the second mixing temperature, and then discharge and cool. S3. Final mixing: Cooled rubber compound is fed into the final mixer, sulfur and sulfenamide accelerators are added, and the mixture is mixed at the final mixing temperature for a preset time, then the rubber is extruded and pressed into sheets. S4. Molding and vulcanization: The rubber sheet obtained in step S3 is used to prepare the bead wear-resistant rubber, which is then bonded to the bead position of the all-steel radial tire and the finished tire is obtained under preset vulcanization conditions.

8. The method for preparing the wear-resistant rubber for the bead of an all-steel radial tire according to claim 7, characterized in that, The first mixing temperature is 140°C. o C~150 o C, the first mixing time is 4~6 minutes; The second mixing temperature is 130. o C~140 o C, the second mixing time is 3~5 minutes.

9. The method for preparing the wear-resistant rubber for the bead of an all-steel radial tire according to claim 8, characterized in that, The final refining temperature is 90°C. o C~100 o C. The preset mixing time is 1.5~3 minutes.

10. The method for preparing the wear-resistant rubber for the bead of an all-steel radial tire according to claim 8, characterized in that, The preset vulcanization conditions include: vulcanization temperature 145°C. o C~155 o C. Vulcanization pressure: 2.5MPa~3.0MPa; Vulcanization time: 40min~50min.

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