Wear-resistant rubber material for seam allowance of all-steel truck radial tire and preparation method of wear-resistant rubber material

Abstract

The invention relates to an all-steel truck radial tire seam allowance wear-resistant rubber material and a preparation method thereof, and belongs to the technical field of all-steel radial tires. The rubber material comprises the following components in parts by mass: 45-50 parts of natural rubber, 50-55 parts of high cis-butadiene rubber, 60-78 parts of high-structure carbon black, 3.0-4.0 parts of zinc oxide, 1-3 parts of stearic acid, 3-4 parts of an anti-aging agent, 1.5-2.5 parts of a homogenizing agent, 1.5-2.5 parts of a plasticizer, 3-5 parts of carbon nanotubes, 4-6 parts of environment-friendly oil, 1-1.5 parts of sulfur, 0.5-1 part of a scorch retarder, 1.5-2.5 parts of an accelerant and 0.5-1 part of a cross-linking agent. The problems of resistance to stress relaxation of the rubber material and overhigh vulcanization thermal reduction degree of various components are integrated, the adaptability of the seam allowance wear-resistant rubber material to complex periodic stress in the using process is improved, the fatigue deformation degree is reduced, and the service life of a tire is further prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of all-steel radial tires, and in particular relates to a wear-resistant rubber for the bead of an all-steel load-carrying radial tire and a preparation method thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] The bead (also known as the tire lip or bead) of a load-bearing all-steel radial tire refers to the area where the inner edge of the tire contacts the wheel hub. It is typically composed of a steel bead and rubber composite structure, used to seal the air and secure the tire. The interior of the bead contains multiple layers of steel cord to enhance deformation resistance and load-bearing performance. During tire use, it has been found that the wear-resistant area of ​​the bead of inner tube tires, especially medium- and short-distance heavy-duty tires, gradually becomes more deformed and difficult to recover due to cyclical loads as the service life increases. This means that fatigue resistance is poor, resulting in a poor fit between the bead wear-resistant rubber compound and the wheel hub, causing excessive tire pressure loss, which can further lead to localized thermal delamination of the tire shoulder and bead.

[0004] Analysis of the reasons for the poor fatigue resistance of the sub-mouth wear-resistant rubber include: (1) Currently, the steamer vulcanization method (vulcanization temperature of 147°C) has been replaced by the more efficient electric vulcanization method. The vulcanization process of electric vulcanization heats up quickly and more often uses high-temperature vulcanization processes (vulcanization temperature of 151°C or even 155°C), making it difficult to control the uniformity of the temperature field. During the vulcanization process, the wear-resistant rubber material at the nozzle is in direct contact with the mold and the nozzle area is thick, resulting in uneven vulcanization of the rubber material in this area and excessive local vulcanization reduction.

[0005] (2) The carbon black filling content of the tire's wear-resistant rubber is large, resulting in greater stress relaxation, which leads to poor fatigue resistance. In addition, when the vehicle is driving for long distances, the temperature of the tire's wear-resistant rubber is higher than that of other parts of the tire, which accelerates the aging of the tire's wear-resistant rubber.

[0006] Therefore, how to improve the fatigue resistance of the wear-resistant rubber material of the sub-mouth is a technical problem that needs to be solved urgently by technical personnel in this field. Summary of the Invention

[0007] In response to the deficiencies in the prior art, the present invention provides a wear-resistant rubber compound for the bead of an all-steel load-bearing radial tire and a preparation method thereof, wherein carbon nanotubes are added as a key component to partially replace carbon black, and a semi-effective vulcanization system is used to form more monosulfide bonds to replace polysulfide bonds, thereby obtaining a wear-resistant rubber compound for the bead having good strength, elasticity, and fatigue resistance, and having resistance to vulcanization reduction.

[0008] In order to achieve the above object, the technical solution of the present invention is: In the first aspect, a wear-resistant rubber compound for the bead of an all-steel load-bearing radial tire comprises the following components in parts by mass: 45-50 parts of natural rubber, 50-55 parts of high-cis-butadiene rubber, 60-78 parts of high-structure carbon black, 3.0-4.0 parts of zinc oxide, 1-3 parts of stearic acid, 3-4 parts of an antioxidant, 1.5-2.5 parts of a leveling agent, 1.5-2.5 parts of a plasticizer, 3-5 parts of carbon nanotubes, 4-6 parts of an environmentally friendly oil, 1-1.5 parts of sulfur, 0.5-1 part of a scorch retarder, 1.5-2.5 parts of a accelerator, and 0.5-1 part of a cross-linking agent.

[0009] In a second aspect, a method for preparing the above-mentioned wear-resistant rubber material for the bead of an all-steel radial truck tire comprises the following steps: S1. Mixing natural rubber and carbon nanotubes, kneading at 125-155° C. to obtain a masterbatch, and cooling for later use; S2. Mix the first-stage masterbatch and 60-70% of the total amount of high-structure carbon black, mix at 140-165° C. to obtain the second-stage masterbatch, and cool for later use.

[0010] S3, the second stage masterbatch, high cis-butadiene rubber, the remaining high structure carbon black, zinc oxide, stearic acid, antioxidant, leveling agent, plasticizer and environmentally friendly oil are mixed, and kneaded at 140-165 ° C to obtain the third stage masterbatch, which is cooled for standby use; S4, mixing the three-stage masterbatch at 148-153° C. to obtain the fourth-stage masterbatch, and cooling it for later use; S5. Mix the four-stage masterbatch, sulfur, sulfenamide vulcanization accelerator, scorch retarder and cross-linking agent, mix at 100-108° C., and discharge the rubber to obtain the wear-resistant rubber compound for the all-steel radial truck tire.

[0011] The beneficial effects of the present invention are: 1. This invention utilizes carbon nanotubes to improve the overall performance of the rubber compound. Multi-walled carbon nanotubes partially replace carbon black, effectively mitigating the Payne effect of the carbon black filling system on the rubber and improving the rubber's wear resistance, tear resistance, and fatigue resistance. A semi-effective vulcanization system replaces a conventional vulcanization system, reducing sulfur usage and replacing traditional polysulfide bonds with single sulfur bonds formed during the vulcanization process, thereby improving the thermal oxidative fatigue resistance of the rubber compound. An accelerator prevents the breakage of natural rubber molecular chains during high-temperature vulcanization, preventing the adverse effects of the vulcanization process. During tire use, the accelerator participates in the thermal oxidative aging molecular chain breakage and recombination, thereby improving the tire's aging resistance. High-surface-area, high-structure carbon black is used to reinforce the rubber compound, effectively increasing its tensile strength and tear resistance, making the rubber compound in contact with the wheel hub more wear-resistant and resistant to cyclic loading. Carbon nanotubes, with their high reinforcing properties, can reduce the amount of carbon black filling and improve the compound's overall physical properties. A low-sulfur, high-accelerator semi-effective vulcanization system improves reversion during vulcanization. The combination of multiple ingredients can resist the problems of stress relaxation of the rubber compound and excessive degree of reduction of vulcanization heat, improve the adaptability of the wear-resistant rubber compound to complex cyclic stress during use, reduce the degree of fatigue deformation, and thus increase the service life of the tire.

[0012] 2. To improve the uniformity of carbon nanotube mixing and dispersion during the preparation process of the present invention, the carbon nanotubes are first premixed with natural rubber to form a carbon nanotube masterbatch. Natural rubber is susceptible to chain scission and plasticization under mechanical shear and high temperatures, so the masterbatch mixing temperature should not exceed 155°C. Carbon black is more easily dispersed in high-cis-butadiene rubber. To ensure uniform dispersion of carbon black in high-cis-butadiene rubber and natural rubber, the natural rubber is first mixed with a portion of the carbon black, followed by the high-cis-butadiene rubber and the remaining carbon black. Due to the high amount of carbon black filler used in the wear-resistant rubber formulation, carbon black tends to agglomerate and disperse unevenly at high temperatures. Therefore, the rubber temperature is controlled below 165°C during carbon black mixing. DETAILED DESCRIPTION

[0013] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0014] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0015] A wear-resistant rubber compound for the bead of an all-steel load-bearing radial tire comprises the following components in parts by mass: 45-50 parts of natural rubber, 50-55 parts of high-cis-butadiene rubber, 60-78 parts of high-structure carbon black, 3.0-4.0 parts of zinc oxide, 1-3 parts of stearic acid, 3-4 parts of an antioxidant, 1.5-2.5 parts of a leveling agent, 1.5-2.5 parts of a plasticizer A, 3-5 parts of carbon nanotubes, 4-6 parts of an environmentally friendly oil, 1-1.5 parts of sulfur, 0.4-1 part of a scorch retarder, 1.5-2.5 parts of an accelerator, and 0.5-1 part of a cross-linking agent.

[0016] Among the above ingredients, high cis (trans) butadiene rubber is a non-crystalline rubber with low strength, needs to be reinforced with carbon black, and has good wear resistance; natural rubber is a crystalline rubber that does not require carbon black reinforcement, has high physical tensile properties, and good fatigue resistance, but its wear resistance is lower than that of high cis butadiene rubber; it is necessary to adjust the proportion of natural rubber used to improve the fatigue performance of wear-resistant rubber, so carbon nanotubes are added to improve the wear resistance, tear resistance and fatigue resistance of the rubber, high-structure carbon black is used to increase the hardness of carbon black, a semi-effective vulcanization system is used to improve the relative resistance to thermal oxidative aging fatigue, and a cross-linking agent is used to promote the breakage and recombination process of the thermal oxidative aging molecular chain, thereby comprehensively improving the fatigue resistance of the sub-mouth wear-resistant rubber under high temperature conditions during service.

[0017] Optionally, the natural rubber is one or more of STR20 grade composite rubber and standard rubber.

[0018] Optionally, the high-structure carbon black includes one or more of N375, N330 and N220; the specific surface area and structure of carbon black are two important technical indicators for the reinforcement performance of rubber. The larger the specific surface area, the better the rubber reinforcement performance, and the higher the tensile strength, tearing performance and wear resistance; the higher the structure of carbon black, the higher the modulus of elasticity and hardness of the rubber; N375 and N330 are highly wear-resistant carbon blacks, which can improve the wear resistance of the finished rubber product. N220 is preferably a medium-super wear-resistant carbon black, which can not only reduce the usage, but also improve the tensile stress, tensile strength and elongation at break of the rubber before and after aging.

[0019] Optionally, the antioxidant is selected from one or more of quinoline antioxidant RD, p-diphenylamine antioxidant 4020 and microcrystalline wax. Quinoline antioxidant RD can improve the wear-resistant rubber's resistance to thermal oxidative aging; p-diphenylamine antioxidant 4020 or 4010NA can improve the wear-resistant rubber's dynamic fatigue; microcrystalline wax can be selected from single-peak wax RW287 or double-peak wax to improve the wear-resistant rubber's resistance to ozone aging; RD, 4020 and microcrystalline wax RW287 are mixed and used in a mass ratio of 1: (1~2): (1~2), which can effectively improve the fatigue resistance and ozone resistance of the wear-resistant rubber.

[0020] Optionally, the homogenizer is 40MSF or RH100 to improve the dispersion of materials with different polarities.

[0021] The plasticizer A is a multi-purpose rubber processing aid with zinc soap salt as the main component, which has internal lubrication, external lubrication and dispersing functions. After addition, it can reduce the viscosity of the rubber material and improve the mixing efficiency. In the processing of natural rubber and synthetic rubber, it can shorten the mixing cycle and reduce the processing temperature.

[0022] Optionally, the carbon nanotubes are selected from one or more of GC-21, TF220 and TF320; they are multi-walled carbon nanotubes with a high aspect ratio, even up to 1000:1, and high tensile strength; carbon nanotubes have a cavity structure, are flattened under huge pressure, and can restore their shape after the pressure is removed, showing good toughness; for medium and short-distance heavy-load tires, especially tubeless heavy-load tires, the tire mouth wear-resistant rubber is subjected to periodic compression deformation during use, and it needs to have toughness to ensure that the tire and the rim maintain a good fit for a long time; in addition, carbon nanotubes have excellent isotropy; adding carbon nanotubes to the tire mouth wear-resistant rubber can enhance tensile strength and fatigue resistance.

[0023] Optionally, the scorch retarder is selected from one or more of sulfenamide CTP, organic acid and nitroso compound.

[0024] Optionally, the main components of the accelerator NS include sulfonamide vulcanization accelerators, which can replace the ordinary vulcanization system with a semi-effective vulcanization system, reduce the amount of sulfur used, replace the polysulfide bonds with single sulfur bonds formed during the vulcanization process, and improve the thermal oxidation aging fatigue resistance of the sub-mouth wear-resistant rubber.

[0025] Optionally, the cross-linking agent is selected from one or more of AP9, AP8 and AP7. Zinc dithiophosphate is the main component of the cross-linking agent AP9, which is a synergistic polymer of thiazole and diphenyl dithiocarbamate vulcanization accelerators. It can effectively prevent the breakage of natural rubber molecular chains during high-temperature vulcanization and can participate in the breakage and recombination of molecular chains during thermal oxidative aging during use.

[0026] In a second aspect, a method for preparing the above-mentioned wear-resistant rubber material for the bead of an all-steel radial truck tire comprises the following steps: S1. Mixing natural rubber and carbon nanotubes, kneading at 125-155° C. to obtain a masterbatch, and cooling for later use; S2. Mix the first-stage masterbatch and 60-70% of the total amount of high-structure carbon black, mix at 140-165° C. to obtain the second-stage masterbatch, and cool for later use.

[0027] S3, the second stage masterbatch, high cis-butadiene rubber, the remaining high structure carbon black, zinc oxide, stearic acid, antioxidant, leveling agent, plasticizer and environmentally friendly oil are mixed, and kneaded at 140-165 ° C to obtain the third stage masterbatch, which is cooled for standby use; S4, mixing the three-stage masterbatch at 148-153° C. to obtain the fourth-stage masterbatch, and cooling it for later use; S5. Mix the four-stage masterbatch, sulfur, sulfenamide vulcanization accelerator, scorch retarder and cross-linking agent, mix at 100-108° C., and discharge the rubber to obtain the wear-resistant rubber compound for the all-steel radial truck tire.

[0028] Optionally, in S1, the speed of the internal mixer is 40~45 rpm; specifically, natural rubber is added to the internal mixer, the rotor speed is adjusted to 45~55 rpm, the top bolt is pressed once, and the mixing time is 30~40S; the top bolt is raised to add carbon nanotubes, the rotor speed is adjusted to 40~45 rpm, the top bolt is pressed twice, and the mixing time is 35~45S, until the rubber temperature is 125~135℃; the top bolt is raised and cleaned, the rotor speed is adjusted to 30~40 rpm, the top bolt is pressed three times, and the rubber temperature is 148~155℃ for discharge.

[0029] Optionally, in S2, the speed of the internal mixer is 30~50 rpm; specifically, a section of masterbatch and high-structure carbon black are added to the internal mixer, the rotor speed is adjusted to 40~50 rpm, the top bolt is pressed once, and the mixing time is 30~40S; the top bolt is raised and cleaned, the rotor speed is adjusted to 35~45 rpm, the top bolt is pressed twice, and the mixing time is 35~45S, until the rubber temperature is 125~135℃; the top bolt is raised, the rotor speed is adjusted to 30~40 rpm, the top bolt is pressed three times, and the rubber temperature is 155~165℃ for discharge.

[0030] Optionally, in S3, the speed of the internal mixer is 25~45 rpm; specifically, the second-stage masterbatch high cis-butadiene rubber, the remaining high-structure carbon black, zinc oxide, stearic acid, antioxidant, homogenizer and plasticizer A are added to the internal mixer, the rotor speed is adjusted to 40~45 rpm, the top bolt is pressed once, and the mixing time is 30~40S; the top bolt is raised and cleaned, and environmentally friendly oil is added, the rotor speed is adjusted to 40~45 rpm, the top bolt is pressed twice, and the mixing time is 15~25S, until the rubber temperature is 140~145℃; the top bolt is raised, the rotor speed is adjusted to 25~35rpm, the top bolt is pressed three times, and the rubber temperature is 155~165℃ for discharge.

[0031] Optionally, in S4, the speed of the internal mixer is 25~45 rpm; specifically, three-stage masterbatch is added to the internal mixer, the rotor speed is adjusted to 35~45 rpm, the top bolt is pressed once, and the mixing time is 25~35 s; the top bolt is raised, the rotor speed is adjusted to 25~35 rpm, the top bolt is pressed twice, and the mixing time is 15~25 s; the top bolt is raised, the rotor speed is adjusted to 25~35 rpm, the top bolt is pressed three times, and the rubber temperature is 148~153°C for discharge.

[0032] Optionally, in S5, the speed of the internal mixer is 15~25 rpm; specifically, four-stage masterbatch, sulfur, accelerator NS, scorch retarder and cross-linking agent are added to the internal mixer, the rotor speed is adjusted to 20~25 rpm, the top bolt is pressed once, and the mixing time is 30~40 s; after the top bolt is raised, the rotor speed is adjusted to 15~20 rpm, the top bolt is pressed twice, and the mixing time is 25~35 s; after the top bolt is raised, the rotor speed is adjusted to 15~20 rpm, the top bolt is pressed three times, and the rubber temperature is 100~108°C for discharge.

[0033] Example 1 A wear-resistant rubber compound for the bead of an all-steel load-bearing radial tire comprises the following components in parts by mass: 50 parts of natural rubber, 50 parts of high-cis-butadiene rubber, 75 parts of high-structure carbon black, 3.5 parts of zinc oxide, 2 parts of stearic acid (SA), 3.6 parts of an antioxidant, 2.0 parts of a leveling agent, 2.0 parts of a plasticizer A, 4 parts of carbon nanotubes, 5 parts of an environmentally friendly oil, 1 part of sulfur, 0.4 parts of a scorch retarder, 2.0 parts of an accelerator, and 1 part of a cross-linking agent.

[0034] Among them, the natural rubber is STR20 grade composite rubber; the high cis-butadiene rubber is selected as BR9000; the high structure carbon black is selected as N330; the carbon nanotubes are selected as GC-21; Zinc oxide is indirect zinc oxide, of which the zinc oxide content is 99%, stearic acid is selected as 1860 stearic acid, and the environmentally friendly oil is selected as TUDALEN5244; the antioxidant is selected as RD, 4020 and microcrystalline wax RW287; the leveling agent is selected as RH100; the anti-scorching agent is selected as CTP, the cross-linking agent is selected as AP9, and the accelerator is selected as NS; among them, RD, 4020 and microcrystalline wax RW287 are mixed and used in a mass ratio of 1:1.6:1, which is used to improve the fatigue resistance and ozone resistance of the wear-resistant rubber.

[0035] The equipment used in the preparation method includes: S1. Use a shearing type internal mixer GK400, set the water temperature in the three zones of the internal mixer to 35±5℃, the upper plug pressure to 0.45±0.05MPa, add natural rubber to the internal mixer, adjust the rotor speed to 45 rpm, press the upper plug once, and mix for 30 seconds; raise the upper plug and add carbon nanotubes, adjust the rotor speed to 40 rpm, press the upper plug twice, and mix for 35 seconds until the rubber temperature reaches 125℃; raise the upper plug and clean it, adjust the rotor speed to 30 rpm, press the upper plug three times, and discharge the rubber at a temperature of 148℃ to obtain a masterbatch.

[0036] S2. Using the same equipment as S1, a masterbatch and 2 / 3 of the total high-structure carbon black (50 parts in this embodiment) were added to the internal mixer, the rotor speed was adjusted to 40 rpm, the top bolt was pressed once, and the mixing time was 30 s; the top bolt was raised and cleaned, the rotor speed was adjusted to 35 rpm, the top bolt was pressed twice, and the mixing time was 35 s, until the rubber temperature reached 125°C; the top bolt was raised, the rotor speed was adjusted to 30 rpm, the top bolt was pressed three times, and the rubber temperature was discharged at 155°C to obtain a second masterbatch.

[0037] S3. Using the same equipment as S1, add the second-stage masterbatch high cis-butadiene rubber, the remaining high-structure carbon black, zinc oxide, stearic acid, antioxidant, homogenizer and plasticizer A into the internal mixer, adjust the rotor speed to 40 rpm, press the top bolt once, and mix for 30 seconds; raise the top bolt, clean the top bolt and add environmentally friendly oil, adjust the rotor speed to 40 rpm, press the top bolt twice, and mix for 15 seconds until the rubber temperature reaches 140°C; raise the top bolt, adjust the rotor speed to 25 rpm, press the top bolt three times, and discharge the rubber at a temperature of 155°C to obtain the three-stage masterbatch.

[0038] S4. Using the same equipment as S1, add three-stage masterbatch into the internal mixer, adjust the rotor speed to 35 rpm, press the top bolt once, and mix for 25 seconds; raise the top bolt, adjust the rotor speed to 25 rpm, press the top bolt twice, and mix for 15 seconds; raise the top bolt, adjust the rotor speed to 25 rpm, press the top bolt three times, and discharge the rubber at a temperature of 148°C to obtain a four-stage masterbatch.

[0039] S5. Use a shear-type internal mixer GK255, set the upper bolt pressure to 0.40±0.05MPa, set the water temperature in the third zone of the internal mixer to 30±5℃, add four-stage masterbatch, sulfur, accelerator NS, scorch retarder and cross-linking agent into the internal mixer, adjust the rotor speed to 20rpm, press the upper bolt once, and mix for 30s; raise the upper bolt, adjust the rotor speed to 15rpm, press the upper bolt twice, and mix for 25s; raise the upper bolt, adjust the rotor speed to 15rpm, press the upper bolt three times, and discharge the rubber at a temperature of 100℃ to obtain the product.

[0040] Example 2 A wear-resistant rubber compound for the bead of an all-steel load-bearing radial tire comprises the following components in parts by mass: 50 parts of natural rubber, 50 parts of high-cis-butadiene rubber, 60 parts of high-structure carbon black, 3.5 parts of zinc oxide, 2 parts of stearic acid (SA), 3.6 parts of an antioxidant, 2.0 parts of a leveling agent, 2.0 parts of a plasticizer A, 4 parts of carbon nanotubes, 5 parts of an environmentally friendly oil, 1 part of sulfur, 0.4 parts of a scorch retarder, 2.0 parts of an accelerator, and 0.65 parts of a cross-linking agent.

[0041] Among them, the high-structure carbon black is selected as N220, and the other raw material requirements are the same as those in Example 1.

[0042] In the preparation method, 40 parts of high-structure carbon black were added to S1, and the other steps were the same as those in Example 1.

[0043] Example 3 A wear-resistant rubber compound for the bead of an all-steel radial truck tire comprises the following components in parts by weight: 50 parts natural rubber, 50 parts high-cis-butadiene rubber, 63 parts high-structure carbon black, 3.5 parts zinc oxide, 2 parts stearic acid (SA), 3.6 parts antioxidant, 2.0 parts leveling agent, 2.0 parts plasticizer A, 4 parts carbon nanotubes, 5 parts environmentally friendly oil, 1 part sulfur, 0.4 parts scorch retarder, 2.0 parts accelerator, and 0.65 parts crosslinking agent. This embodiment differs from Example 2 in that the amount of high-structure carbon black added is increased.

[0044] The raw material requirements and preparation methods are the same as those in Example 2.

[0045] Example 4 A wear-resistant rubber compound for the bead of an all-steel radial truck tire comprises the following components, in parts by weight: 50 parts natural rubber, 50 parts high-cis-butadiene rubber, 65 parts high-structure carbon black, 3.5 parts zinc oxide, 2 parts stearic acid (SA), 3.6 parts antioxidant, 2.0 parts leveling agent, 2.0 parts plasticizer A, 4 parts carbon nanotubes, 5 parts environmentally friendly oil, 1 part sulfur, 0.4 parts scorch retarder, 2.0 parts accelerator, and 0.65 parts crosslinking agent. This embodiment differs from Example 2 in that the amount of high-structure carbon black added is increased.

[0046] The raw material requirements and preparation methods are the same as those in Example 2.

[0047] Comparative Example 1 A wear-resistant rubber compound for the bead of an all-steel radial truck tire comprises the following components, in parts by weight: 45 parts natural rubber, 55 parts high-cis-butadiene rubber, 78 parts high-structure carbon black, 3.5 parts zinc oxide, 2 parts stearic acid (SA), 3.6 parts antioxidant, 2.0 parts leveling agent, 2.0 parts plasticizer A, 5 parts environmentally friendly oil, 1 part sulfur, 0.4 part scorch retarder, and 2.0 parts accelerator. This embodiment differs from Example 1 in that carbon nanotubes and a crosslinking agent are omitted, and the amount of high-structure carbon black added is increased.

[0048] The raw material requirements and preparation methods are the same as those in Example 1.

[0049] Comparative Example 2 A wear-resistant rubber compound for the bead of an all-steel radial truck tire comprises the following components by weight: 45 parts natural rubber, 55 parts high-cis-butadiene rubber, 75 parts high-structure carbon black, 3.5 parts zinc oxide, 2 parts stearic acid (SA), 3.6 parts antioxidant, 2.0 parts leveling agent, 2.0 parts plasticizer A, 4 parts carbon nanotubes, 5 parts environmentally friendly oil, 1 part sulfur, 0.4 parts scorch retarder, and 2.0 parts accelerator. This differs from Example 1 in that no crosslinking agent is added.

[0050] The raw material requirements and preparation methods are the same as those in Example 1.

[0051] Comparative Example 3 A wear-resistant rubber compound for the bead of an all-steel radial truck tire comprises the following components in parts by weight: 45 parts natural rubber, 55 parts high-cis-butadiene rubber, 75 parts high-structure carbon black, 3.5 parts zinc oxide, 2 parts stearic acid (SA), 3.6 parts antioxidant, 2.0 parts leveling agent, 2.0 parts plasticizer A, 5 parts environmentally friendly oil, 1 part sulfur, 0.4 parts scorch retarder, 2.0 parts accelerator, and 1.0 part crosslinking agent. This differs from Example 1 in that no carbon nanotubes are added.

[0052] The raw material requirements and preparation methods are the same as those in Example 1.

[0053] Comparative Example 4 A wear-resistant rubber compound for the bead of an all-steel load-bearing radial tire comprises the following components in parts by mass: 50 parts of natural rubber, 50 parts of high-cis-butadiene rubber, 63 parts of high-structure carbon black, 3.5 parts of zinc oxide, 2 parts of stearic acid (SA), 3.6 parts of an antioxidant, 2.0 parts of a leveling agent, 2.0 parts of a plasticizer A, 5 parts of an environmentally friendly oil, 1 part of sulfur, 0.4 parts of a scorch retarder, and 2.0 parts of an accelerator.

[0054] The high-structure carbon black is N330. The difference from Example 2 is that no carbon nanotubes and cross-linking agent are added.

[0055] The other raw material requirements and preparation methods are the same as those in Example 2.

[0056] Performance testing Test the tensile stress variation properties of vulcanized rubber according to GB T528 standard; Test the international hardness of vulcanized rubber according to GB T6031 standard; Test the right-angle tearing properties of vulcanized rubber according to GB T529 (uncut) Test the density properties of vulcanized rubber according to standard GB T 533; Determine the Mooney viscosity of unvulcanized rubber according to GB T 1232.1; Test the wear resistance of vulcanized rubber according to GB T 9867 (using the rotating roller method); Test the temperature rise and fatigue resistance of vulcanized rubber in the flexure test according to GB T 1687.3 (using the constant strain compression test method); Test the hot air aging and heat resistance performance of vulcanized rubber according to GB T 3512 standard; The Mooney stress relaxation properties of unvulcanized rubber were tested according to GB T 1232.4 standard.

[0057] The performance results obtained are shown in Table 1.

[0058] Table 1

[0059] It can be seen that the use of carbon nanotubes can effectively improve the physical properties of the rubber after aging: after the basic formula is aged, the tensile properties of the vulcanized rubber increase by 9.5%, the tensile stress increases by 69%, and the tear strength increases by 10%; the hardness of the rubber increases by 7.5%; the wear resistance decreases by 5%, mainly due to the large change in the elongation at break after the use of nanotubes, which decreases by about 20%; the stress relaxation α of the rubber is significantly improved by about 40%; the vulcanization heat reduction increases by about 21.5%; Using AP9 can increase Mooney scorch time by about 13%; modulus of tensile stress, tensile strength, and tear strength are also improved; Therefore, both carbon nanotubes and AP9 can increase the tensile stress of vulcanized rubber, improve the stress relaxation of the rubber, and improve the thermal reduction of rubber vulcanization; the Mooney viscosity of the rubber increases significantly, and the compression heat generation of the rubber is relatively high.

[0060] The same method was used to test Examples 2 to 4 and Comparative Example 4, and the performance results obtained are shown in Table 2.

[0061] Table 2

[0062] It can be seen that the use of high specific surface area and high structure N220 carbon black instead of N330 / N326 / N375 and the reduction of carbon black usage can significantly improve the tensile strength, elongation at break and tear strength of the rubber compound; before aging, the tensile stress of the rubber compound increased by 8.3-22.3%; the tensile strength increased by 4-6%, the tear strength increased by 11.8-17.1%, and the elongation increased by 27%; after aging, the tensile stress at break, tensile strength and elongation of the rubber compound were all improved; in particular, the aging retention rate was 85-92%, and the tear strength retention rate was above 90%; the stress relaxation α of the rubber compound was increased by 10%; and the thermal vulcanization reduction of the rubber compound was reduced by 46%.

[0063] The changes in the rubber's wear resistance and hardness are relatively small. The use of carbon nanotubes and AP9 materials in the rubber has a relatively high compression heat generation, which is mainly due to the higher modulus and elongation of the rubber.

[0064] From the above data, it can be seen that by adjusting the rubber ratio, adjusting the amount of sulfur used, using carbon nanotubes, and AP9, the tensile stress, tensile strength, elongation at break, and tear strength of the rubber before and after aging are improved, especially the stress relaxation of the rubber and the improvement of vulcanization heat reduction are more obvious, which improves the adaptability of the sub-mouth wear-resistant rubber to complex cyclic stress and deformation during use and improves its service life.

[0065] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A wear-resistant rubber compound for the bead of an all-steel radial truck tire, characterized by comprising: The following components are included in parts by mass: 45-50 parts of natural rubber, 50-55 parts of high cis-butadiene rubber, 60-78 parts of high-structure carbon black, 3.0-4.0 parts of zinc oxide, 1-3 parts of stearic acid, 3-4 parts of antioxidant, 1.5-2.5 parts of homogenizer, 1.5-2.5 parts of plasticizer, 3-5 parts of carbon nanotubes, 4-6 parts of environmentally friendly oil, 1-1.5 parts of sulfur, 0.5-1 part of scorch retarder, 1.5-2.5 parts of accelerator and 0.5-1 part of crosslinking agent.

2. The wear-resistant rubber compound for the bead of the all-steel radial truck tire according to claim 1, characterized in that: The natural rubber is one or more of STR20 grade composite rubber and standard rubber.

3. The wear-resistant rubber compound for the bead of the all-steel radial truck tire according to claim 1, characterized in that: The high structure carbon black includes one or more of N375, N330 and N220, preferably N220.

4. The wear-resistant rubber compound for the bead of the all-steel radial truck tire according to claim 1, characterized in that: The antioxidant is selected from one or more of RD, 4020 and microcrystalline wax.

5. The wear-resistant rubber compound for the bead of the all-steel radial truck tire according to claim 1, characterized in that: The homogenizer is RH100 or 40MSF.

6. The wear-resistant rubber compound for the bead of the all-steel radial truck tire according to claim 1, characterized in that: The carbon nanotubes are selected from one or more of GC-21, TF220 and TF320.

7. The wear-resistant rubber compound for the bead of the all-steel radial truck tire according to claim 1, characterized in that: The scorch retarder is selected from one or more of sulfenamide CTP, organic acid and nitroso compound.

8. The wear-resistant rubber compound for the bead of the all-steel radial truck tire according to claim 1, characterized in that: The cross-linking agent is selected from one or more of AP9, AP8 and AP7.

9. A method for preparing the wear-resistant rubber compound for the bead of an all-steel radial truck tire according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Mixing natural rubber and carbon nanotubes, kneading at 125-155° C. to obtain a masterbatch, and cooling for later use; S2, mixing the first stage masterbatch and 60-70% of the total amount of high structure carbon black, mixing at 140-165° C. to obtain the second stage masterbatch, and cooling for standby use; S3, the second stage masterbatch, high cis-butadiene rubber, the remaining high structure carbon black, zinc oxide, stearic acid, antioxidant, leveling agent, plasticizer and environmentally friendly oil are mixed, and kneaded at 140-165 ° C to obtain the third stage masterbatch, which is cooled for standby use; S4, mixing the three-stage masterbatch at 148-153° C. to obtain the fourth-stage masterbatch, and cooling it for later use; S5. Mix the four-stage masterbatch, sulfur, sulfenamide vulcanization accelerator, scorch retarder and cross-linking agent, mix at 100-108° C., and discharge the rubber to obtain the wear-resistant rubber compound for the all-steel radial truck tire.

10. The method for preparing the tire tread rubber composition according to claim 9, wherein: In S1, the internal mixer speed is 40-45 rpm; Alternatively, in S2, the internal mixer speed is 30-50 rpm; Alternatively, in S3, the internal mixer speed is 25-45 rpm; Alternatively, in S4, the internal mixer speed is 25-45 rpm; Alternatively, in S5, the internal mixer speed is 15-25 rpm.

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