High-thermal-stability environment-friendly CBS and preparation method thereof

Abstract

The invention discloses environment-friendly CBS with high thermal stability and a preparation method of the environment-friendly CBS in the field of rubber assistants.According to the material, N-cyclohexylbenzothiazole sulfenamide serves as a basis, and an autonomously-synthesized boron-nitrogen heterocyclic compound stabilizer and a silane-based green dispersing agent are innovatively introduced; according to the present invention, with the cooperation of the dioctyl sebacate, the calcium zinc stearate compound, the hindered phenol antioxidant and other components, the composite material is prepared through the precise ratio and the melting composite process; the preparation method comprises the key steps of raw material pretreatment, high-speed mixing, multi-temperature-zone controllable extrusion, underwater pelletizing, cryogenic crushing and the like. The two key modified compounds are synthesized through a boron-nitrogen heterocyclic ring construction reaction and a silane-based polyurethane grafting reaction respectively. The heat stability of the product and the dispersity of the product in a rubber matrix are remarkably improved, meanwhile, the environment-friendly characteristic is good, the safe operation time of rubber processing is effectively prolonged, the physical performance of vulcanized rubber is improved, and the rubber composition is suitable for production of high-performance rubber products.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rubber auxiliaries, in particular to a high-thermal-stability environmentally-friendly CBS and a preparation method thereof. BACKGROUND

[0002] Rubber vulcanization accelerators play a crucial role in the rubber industry, among which N-cyclohexyl-benzothiazole sulfenamide is a typical representative of post-effect accelerators. Due to its good processing safety before vulcanization temperature and its ability to rapidly decompose and produce high-efficiency promoting effect at vulcanization temperature, it is widely used in the production process of tires, rubber hoses, conveyor belts and other various rubber products. With the continuous development of the rubber industry, the quality requirements for rubber products are increasingly improved, especially in terms of stability at high-temperature processing conditions and environmental performance, which puts forward more stringent standards. Traditional accelerators are prone to thermal decomposition during high-temperature mixing and processing, which changes the vulcanization characteristics, not only affecting the physical and mechanical properties of the final product, but also potentially causing potential harm to the production environment and the health of the operators due to the volatilization of decomposition products.

[0003] However, the traditional accelerators in the prior art have inherent limitations in molecular structure design, and their thermal stability cannot meet the requirements of modern high-performance rubber products. Under high-temperature processing conditions, traditional products are prone to molecular chain rupture or rearrangement, resulting in a decrease in promoting efficiency and possibly causing early vulcanization of the rubber compound, which significantly affects the stability of the production process. Although the industry has tried to improve this situation by adding various auxiliary stabilizers or changing the synthesis process, most of these improvement methods can only delay the decomposition process to some extent and cannot fundamentally solve the problem of thermal instability of the molecular structure. In addition, these improvement measures often bring new problems, such as reducing the promoting efficiency, affecting the integrity of the vulcanized rubber network structure, or introducing new environmental hazards, making it difficult to achieve an ideal balance of the overall performance of the product.

[0004] With the increasingly stringent global environmental regulations and the deepening of the concept of green manufacturing, the development of rubber auxiliaries with excellent thermal stability and environmental friendliness has become an urgent need in the industry. There is a lack of accelerator products on the market that can simultaneously meet the requirements of high-temperature processing stability and environmental standards, which seriously hinders the development and application of high-performance environmentally-friendly rubber products. The existing technology for improving the thermal stability of accelerators mainly focuses on physical mixing modification or simple molecular modification, which fails to achieve a fundamental breakthrough from the perspective of molecular structure design and does not fully consider the environmental impact of the product throughout its life cycle. Therefore, it is urgent to develop a new generation of high-thermal-stability environmentally-friendly accelerators through innovative molecular design and synthesis process innovation, in order to promote the transformation and upgrading of the rubber industry towards high quality and environmental friendliness. SUMMARY

[0005] The present application aims to provide a high-thermal-stability environmentally-friendly CBS and a preparation method thereof, which solves the technical problems of insufficient thermal stability of existing rubber vulcanization accelerators, easy decomposition and failure under high-temperature processing conditions, and environmental unfriendliness of components.

[0006] The present application achieves the above-mentioned purpose through the following technical solutions: A high-thermal-stability environmentally-friendly CBS, the steps comprising: S1, drying N-cyclohexyl-2-benzothiazolesulfenamide in a 78-82℃ vacuum drying box; crushing and sieving the dried N-cyclohexyl-2-benzothiazolesulfenamide to obtain pretreated N-cyclohexyl-2-benzothiazolesulfenamide powder; adding the pretreated N-cyclohexyl-2-benzothiazolesulfenamide powder, boron-nitrogen heterocyclic complex stabilizer, silane-based green dispersant, dioctyl sebacate, calcium-zinc stearate complex stabilizer, and pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) into a high-speed mixer to obtain a mixture; S2, transferring the mixture into a twin-screw extruder to perform melt compounding; the extruder temperature is set as follows: zone 1 118-122℃, zone 2 138-142℃, zone 3 158-162℃, zone 4 148-152℃, and head 133-137℃; cutting the extruded melt material into particles through an underwater pelletizer, cooling the particles through a cooling water tank to obtain cooled particles; performing ultrafine pulverization of the cooled particles under liquid nitrogen to obtain pulverized powder, and sieving the pulverized powder.

[0007] In the present application, the final composite preparation of high-thermal-stability environmentally-friendly CBS is a multi-scale and multi-process synergistic physicochemical process involving physical mixing, interface infiltration, melting dispersion and stable structure construction. The process starts with accurate metering and pre-mixing of each component. Under the action of mechanical force, each solid powder component is initially dispersed and interwoven. At this time, the liquid environmentally-friendly plasticizer plays a preliminary infiltration role, wrapping around the surface of the promoter base particles, thereby reducing the interfacial energy for subsequent melting compounding. When the mixture enters the twin-screw extruder and undergoes melting compounding, the mechanism enters the core stage. Under the combined action of external heat and high shear force, the crystal surface of the base promoter melts microscopically. At the same time, the boron-nitrogen heterocyclic composite stabilizer remains solid due to its high melting point and rigid structure, but the surface coordination atoms are activated. The silane-based green dispersant is completely melted, and its molecules strongly adsorb on the surface of the base promoter particles through van der Waals forces and hydrogen bonds, forming an organic coating film. Under strong shear and mixing, this coating film is uniformly stretched, fully exposing the silane groups and grafted segments in the dispersant molecules at the interface. Subsequently, the boron-nitrogen heterocyclic stabilizer begins to play a key role, with its boron and nitrogen Lewis acid-base sites forming directional coordination with the sulfenamide groups in the base promoter molecules and the nitrogen and sulfur atoms on the benzothiazole ring, forming stable intermolecular coordination complexes. This coordination is like "molecular pinning", which firmly locks the stabilizer near the surface or lattice defects of the promoter particles. The silane groups of the dispersant may also undergo condensation under the action of heat, further strengthening the interface layer. The auxiliary stabilizer is uniformly dispersed in the system, ready to neutralize any trace of acidic substances. Finally, in the cooling and solidification stage, these multi-level and stable interface structures constructed by coordination bonds, adsorption and possible condensation reactions are fixed, forming a protective shell around the base promoter, with the outer layer composed of stabilizers and dispersants. This shell not only physically blocks the invasion of heat and oxygen, but also chemically stabilizes the active centers of the promoter molecules, thereby macroscopically exhibiting unprecedented high thermal stability and storage stability, while also having excellent dispersibility in the rubber matrix.

[0008] According to the preferred embodiment of the present application, in step S1, the drying time in the 78-82℃ vacuum drying box is 4-6h.

[0009] According to the preferred embodiment of the present application, in step S2, the average residence time of the mixture in the extruder is 2-3min.

[0010] According to the preferred embodiment of the present application, the preparation method of the boron-nitrogen heterocyclic compound stabilizer comprises: A1, under the protection of nitrogen, 2,4,6-trimethylboron-nitrogen cyclohexane and 3-tert-butyl-4-hydroxyphenylpropionic acid are dissolved in anhydrous tetrahydrofuran, and stirred until completely dissolved; triethylamine is added, and stirred at 50-55℃ for reaction; 9-borabicyclo[3.3.1]nonane is added, and refluxed at 50-55℃ for reaction, to obtain a reaction mixture; the reaction mixture is cooled to room temperature, N-methylpyrrolidone is added, and continued to react at 78-82℃; A2, after the reaction is completed, a viscous liquid is obtained by reduced pressure distillation; a mixed solvent of deionized water and ethanol is added to the viscous liquid, and crystallized at 0-5℃; white crystals are collected by filtration, and dried in a vacuum drying oven at 48-52℃.

[0011] In the present application, the synthesis of the boron-nitrogen heterocyclic compound stabilizer is a precise chemical process based on molecular structure reorganization and synergistic coordination. The preparation mechanism starts from the initial interaction between the boron-nitrogen ring compound with a rigid planar structure and the phenolic derivative containing steric hindrance in the presence of the basic catalyst triethylamine. The basic environment helps to activate the phenolic hydroxyl group, which coordinates with the boron atom on the boron-nitrogen ring with certain Lewis acidity to form an activated intermediate. This step lays the foundation for the subsequent reaction. Subsequently, the introduction of the boron heterocyclic compound with high tension and strong Lewis acidity is the key to the whole reaction. The boron heterocyclic reagent initiates an electrophilic attack on the aforementioned intermediate with its unique electron-deficient characteristics. The attack site occurs precisely on the nitrogen atom of the original boron-nitrogen ring, triggering a complex intramolecular cyclization and expansion reaction. In this process, the chemical bonds of the original boron-nitrogen ring break and reorganize, and new boron-nitrogen bonds and boron-oxygen bonds are formed in succession, ultimately constructing a more stable boron-nitrogen-oxygen three-membered heterocyclic structure with a larger conjugated system. The boron atom and nitrogen atom in the new heterocyclic structure both have lone pair electrons, which can serve as potential coordination sites. In the final maturation stage, in a polar aprotic solvent, the reaction groups further adjust their orientations, allowing the entire molecule to form a rigid planar configuration with the lowest energy and greatest stability. This unique heterocyclic structure endows the stabilizer with excellent thermal stability, and the coordination atoms in the molecule can produce strong coordination with sulfur and nitrogen atoms in the main promoter molecules, effectively inhibiting the thermal decomposition of the main promoter at high temperatures like a solid barrier.

[0012] According to the preferred embodiment of the present application, in step A1, the reflux reaction time at 50-55℃ is 4-6h; the continued reaction time at 78-82℃ is 6-8h.

[0013] According to the preferred embodiment of the present application, in step A2, the crystallization time at 0-5℃ is 12-14h.

[0014] According to the preferred embodiment of the present application, the preparation method of the silane-based green dispersant comprises: B1, dissolving 3-isocyanate propyl triethoxysilane and polyethylene glycol monomethyl ether in toluene, adding dibutyl tin dilaurate, refluxing at 84-86℃ to obtain a silane-based polyurethane prepolymer solution; adding glycidyl methacrylate and 2,2,6,6-tetramethylpiperidine-1-oxyl radical, and reacting at 110-115℃; B2, after the reaction is completed, cooling the system to room temperature; through vacuum distillation, a viscous liquid is obtained; adding n-hexane to the viscous liquid, and filtering to obtain a white solid; drying the white solid in a vacuum drying oven at 38-42℃.

[0015] In the present application, the preparation mechanism of the silane-based green dispersant is a combination of step-by-step polymerization and controlled grafting. The first step of the mechanism is a typical step-by-step polymerization, i.e. the addition of isocyanate and alcohol. The silane coupling agent containing isocyanate groups and the polyethylene glycol ether with terminal hydroxyl groups undergo a highly efficient polymerization reaction under the catalysis of an organic metal catalyst. The catalyst activates the hydroxyl groups at the end of the polyether chain to perform nucleophilic addition on the carbon-nitrogen double bond in the isocyanate group, generating a stable carbamate bond, thereby successfully introducing a silane group into one end of the polymer chain, forming a linear prepolymer with a polyether flexible segment and a terminal hydrolyzable silane group. The second step is the core of the functional expansion of the dispersant, and its mechanism is based on the grafting copolymerization reaction regulated by the stable nitroxyl radical. The acrylate monomer containing an epoxy group and the stable nitroxyl radical compound are added to the prepolymer system, and under heating conditions, the nitroxyl radical captures the free radical species that may be generated in the system, forming a dormant species. The dormant species can reversibly cleave at a specific temperature to generate active radicals, thereby initiating the polymerization of the acrylate monomer. This controlled process ensures that the polyacrylate segment is grafted to the polyurethane main chain in an orderly manner, while the epoxy groups on the side chain are perfectly preserved. The finally formed dispersant molecule has multiple functions: the polyether segment provides steric hindrance effect and flexibility; the silane end group confers chemical bonding ability with inorganic fillers or rubber matrix; the grafted fluorine-containing polyacrylate segment brings excellent lubrication and migration; and the abundant epoxy groups serve as strong polar groups, greatly enhancing the physical adsorption and interaction force with the surface of the main accelerator particles. The synergistic effect of multiple functional groups enables it to be firmly anchored on the surface of the accelerator particles and form a steric barrier layer through the stretched polymer segment, thereby achieving excellent dispersion and stabilization effect.

[0016] According to the preferred embodiment of the present application, in step B1, the reflux reaction time at 84-86℃ is 5-7h; and the reaction time at 110-115℃ is 3-5h.

[0017] According to the preferred embodiment of the present application, in step B2, the drying time in the vacuum drying oven at 38-42℃ is 6-8h.

[0018] The application also provides a high-thermal-stability environmentally-friendly CBS prepared according to the preparation method of the high-thermal-stability environmentally-friendly CBS.

[0019] The application has the following beneficial effects: The high-thermal-stability environmentally-friendly CBS of the application has significantly improved comprehensive performance through innovative formula design and preparation process. First, the product has made a breakthrough in thermal stability, which is mainly due to the introduction of a specially designed boron-nitrogen heterocyclic composite stabilizer. The stabilizer can form a stable coordination structure with the base accelerator molecules, effectively inhibiting the chain scission and rearrangement of the molecules under high temperature conditions, so that the thermal decomposition temperature of the product during rubber processing is greatly improved. This unique stabilizing mechanism significantly prolongs the processing safety window and effectively prevents the early vulcanization of the rubber compound during mixing and molding, providing reliable protection for the production of rubber products under high-temperature process conditions. At the same time, the special structural units in the composite stabilizer can also interact with the rubber molecular chain, further enhancing the stability of the vulcanized rubber network.

[0020] In terms of dispersibility and processing performance, the silane-based green dispersant used in the application plays a key role. The special groups in the molecule of the dispersant can significantly improve the compatibility and uniformity of the components in the rubber matrix, effectively preventing the agglomeration of accelerator particles and ensuring the full play of vulcanization activity. By reducing the interfacial tension between the components, the compounding agent can be more uniformly distributed in the compound, which not only improves the vulcanization efficiency, but also makes the physical and mechanical properties of the vulcanized rubber more uniform and stable. In addition, the flexible segment and polar group in the dispersant work together to provide good internal lubrication during processing, significantly reducing the Mooney viscosity of the compound and improving the extrusion and molding performance, creating favorable conditions for the production of high-quality rubber products.

[0021] In terms of environmental protection and safety performance, the application has significantly improved the environmental friendliness of the product by selecting environmentally friendly components and optimizing the formula structure. The plasticizer used is an environmentally friendly ester of biological origin, which does not contain any harmful substances and will not produce toxic volatile substances during use. The auxiliary stabilizer uses a non-toxic metal soap compound, fully meeting the latest environmental regulations. It is particularly worth emphasizing that the molecular structure of the two core modified compounds is carefully designed to ensure their biodegradability under natural conditions, greatly reducing the potential impact on the ecological environment. At the same time, the product does not use any restricted substances, which will not harm the health of the operating personnel during production and use, fully embodying the concept of green manufacturing and providing strong support for the sustainable development of the rubber industry. DETAILED DESCRIPTION

[0022] The following detailed description is merely intended to further illustrate the present application and is not to be understood to limit the scope of the application, which is defined by the appended claims. Those skilled in the art can make some non-essential improvements and adjustments to the present application according to the above application content.

[0023] The main related equipment and material suppliers are as follows: The N-cyclohexyl-2-benzothiazolesulfenamide was purchased from Shandong Shangshun Chemical Co., Ltd. The dioctyl sebacate was purchased from Shandong Qilu Petrochemical Kai Tai Industrial Co., Ltd. The calcium zinc stearate composite stabilizer was purchased from Guangdong Guangxing New Material Co., Ltd. The pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate was purchased from Tianjin Liyanlong New Material Co., Ltd. The 2,4,6-trimethylborazine was purchased from Ningbo Mexis Technology Co., Ltd. The 3-tert-butyl-4-hydroxyphenyl propionic acid was purchased from Jiangsu Maidaxin Material Co., Ltd. The triethylamine was purchased from Shandong Jinling Chemical Co., Ltd. The 9-borabicyclo[3.3.1]nonane was purchased from Tianjin Xinsisheng Biochemical Technology Co., Ltd. The 3-isocyanate propyl triethoxysilane was purchased from Hubei Xinlantian New Material Co., Ltd. The polyethylene glycol monomethyl ether was purchased from Jiangsu Hai'an Petrochemical Factory. The glycidyl methacrylate was purchased from Zhejiang Royal New Material Technology Co., Ltd. The 2,2,6,6-tetramethylpiperidine-1-oxyl radical was purchased from Changzhou Qiangli Electronic New Material Co., Ltd.

[0024] Example 1 1000g N-cyclohexyl-2-benzothiazolesulfenamide is dried in a vacuum oven at 80°C for 5h, and then pulverized using a pulverizer and passed through a 200 mesh screen to obtain pretreated CBS powder for use; begin preparation of a boron-nitrogen heterocyclic composite stabilizer, under a nitrogen protection environment, 120g 2,4,6-trimethylborazine and 180g 3-tert-butyl-4-hydroxyphenylpropionic acid are dissolved in 800mL anhydrous tetrahydrofuran solvent, a mechanical stirrer is used to stir at a speed of 300rpm until complete dissolution, 50g triethylamine is added as a catalyst, and constant stirring is carried out at a constant temperature of 52°C for 3h; then 150g 9-borabicyclo[3.3.1]nonane is added to the reaction system, and reflux reaction is carried out at a temperature of 52°C for 5h, after the reaction is completed, the mixed system is naturally cooled to room temperature of 25°C, 500mL N-methylpyrrolidone is added as a solvent, the temperature is raised to 80°C, and the reaction is continued for 7h; the volatile solvent is removed by 50°C reduced pressure distillation to obtain a viscous liquid, a mixed solvent composed of 400mL deionized water and 200mL ethanol is added to the liquid, and crystallization is carried out at a low temperature of 2°C for 13h, white crystals are collected by vacuum filtration device, and the obtained crystals are placed in a vacuum drying oven at 50°C for 7h to obtain the final boron-nitrogen heterocyclic composite stabilizer; then a silane-based green dispersant is prepared, 100g 3-isocyanate propyl triethoxysilane and 120g polyethylene glycol monomethyl ether are dissolved in 600mL toluene solvent, 1.5g dibutyltin dilaurate is added as a catalyst, and reflux reaction is carried out at a temperature of 85°C for 6h to obtain a silane-based polyurethane prepolymer solution; 45g glycidyl methacrylate and 4g 2,2,6,6-tetramethylpiperidine-1-oxyl free radical are added to the prepolymer solution in sequence, the reaction temperature is adjusted to 112°C, and the reaction is continued for 4h; after the reaction is completed, the system is naturally cooled to room temperature of 25°C, toluene solvent is removed by 40°C reduced pressure distillation to obtain a viscous liquid, 800mL n-hexane is added to the liquid for precipitation treatment, and white solid product is obtained by vacuum filtration, which is placed in a vacuum drying oven at 40°C for 7h to obtain the final silane-based green dispersant; finally, a high-heat-stable environmentally friendly CBS composite is prepared, 800g pretreated CBS powder, 100g self-made boron-nitrogen heterocyclic composite stabilizer, 80g self-made silane-based green dispersant, 50g dioctyl sebacate, 30g calcium-zinc stearate composite stabilizer, and 15g pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate are put into a high-speed mixer at a speed of 600rpm for 12min to obtain a uniform mixture; the mixture is transferred into a twin-screw extruder for melt composite processing, the temperatures of the respective regions are set as follows: zone 1 120°C, zone 2 140°C, zone 3 160°C, zone 4 150°C, and die head 135°C, and the average residence time of the material in the extruder is 2.The extruded molten material is processed into 2mm diameter pellets by an underwater pelletizer, then solidified and cooled in a 12℃ circulating cooling water bath. The resulting pellets are then subjected to ultrafine pulverization in a liquid nitrogen environment, and finally passed through a 325-mesh sieve to obtain the high thermal stability environmentally friendly CBS product.

[0025] Example 2 The specific implementation method is the same as in Example 1, except that 850g of N-cyclohexyl-2-benzothiazole sulfenamide is vacuum dried at 79℃ for 5.5h and then pulverized through a 200-mesh sieve. Preparation of stabilizer: 110g of 2,4,6-trimethylborocyclohexane and 170g of 3-tert-butyl-4-hydroxyphenylpropionic acid are dissolved in 750mL of tetrahydrofuran, and 45g of triethylamine is added. The mixture is reacted at 51℃ for 3.5h; 140g of 9-boronadicyclo[3.3.1]nonane is added and refluxed for 4.5h; then 450mL of N-methylpyrrolidone is added and the mixture is reacted at 79℃ for 7.5h. Preparation of dispersant: 95g of 3-isocyanate-propyltriethoxysilane and 110g of polyethylene glycol monomethyl ether were dissolved in 550mL of toluene, 1.2g of catalyst was added, and the mixture was refluxed at 84℃ for 5.5h; 42g of glycidyl methacrylate and 3.5g of nitroxide free radicals were added, and the mixture was reacted at 111℃ for 3.5h. 850g of CBS powder was mixed with 80g of stabilizer, 60g of dispersant, 40g of dioctyl sebacate, 25g of metal soap stabilizer, and 12g of antioxidant for 10min, and then treated in a twin-screw extruder at temperatures ranging from 119℃, 139℃, 159℃, 149℃, to 134℃ for 2.2min.

[0026] Example 3 The specific implementation method is the same as in Example 1, except that 900g of N-cyclohexyl-2-benzothiazole sulfenamide is dried at 81℃ for 4.5h and then pulverized through a 200-mesh sieve. Preparation of stabilizer: 130g of 2,4,6-trimethylborocyclohexane and 190g of 3-tert-butyl-4-hydroxyphenylpropionic acid are dissolved in 850mL of tetrahydrofuran, and 55g of triethylamine is added. The mixture is reacted at 54℃ for 2.5h; 160g of 9-boronadicyclo[3.3.1]nonane is added and refluxed for 5.5h; then 550mL of N-methylpyrrolidone is added and the mixture is reacted at 81℃ for 6.5h. Preparation of dispersant: 105g of 3-isocyanatopropyltriethoxysilane and 130g of polyethylene glycol monomethyl ether were dissolved in 650mL of toluene, 1.8g of catalyst was added, and the mixture was refluxed at 86℃ for 6.5h; 48g of glycidyl methacrylate and 4.5g of nitroxide free radicals were added, and the mixture was reacted at 114℃ for 4.5h. 900g of CBS powder was mixed with 120g of stabilizer, 100g of dispersant, 60g of dioctyl sebacate, 35g of metal soap stabilizer, and 18g of antioxidant for 14min, and then treated in a twin-screw extruder at temperatures ranging from 121℃, 141℃, 161℃, 151℃, to 136℃ for 2.8min.

[0027] Comparative Example 1 The specific implementation is the same as Example 1, except that the boron-nitrogen heterocyclic composite stabilizer is not added, and the 100 g mass thereof is replaced with an equal amount of N-cyclohexyl-2-benzothiazole sulfenamide.

[0028] Comparative Example 2 The specific implementation is the same as Example 1, except that the silane-based green dispersant is not added, and the 80 g mass thereof is replaced with an equal amount of N-cyclohexyl-2-benzothiazole sulfenamide.

[0029] Comparative Example 3 The specific implementation is the same as Example 1, except that the boron-nitrogen heterocyclic composite stabilizer and the silane-based green dispersant are not added, and the total mass of 180 g thereof is replaced with an equal amount of N-cyclohexyl-2-benzothiazole sulfenamide.

[0030] Performance Test The performance of the high-heat stability environmentally friendly CBS provided by the above examples and comparative examples is tested, and the test method is as follows: According to the test specifications of national and industry standards, the system performance of the high-heat stability environmentally friendly CBS samples obtained in Examples 1-3 and Comparative Examples 1-3 is evaluated. The thermal stability test is performed by using a thermal gravimetric analyzer, 10 mg of sample is placed in an alumina crucible, heated from 50°C to 600°C at a rate of 10°C / min under a nitrogen atmosphere of 50 mL / min, and the temperature at which the sample loses 5% of its weight is recorded as the thermal decomposition temperature; the processing safety test is performed by using a Mooney viscometer according to the national standard, 2.0 g of sample is weighed and mixed with 100 g of standard natural rubber formula on an open mill, and the scorch time, i.e. the time required for the Mooney viscosity value to rise by 5 units, is tested at 125°C; the curing property test is performed by using a non-rotor vulcanizer, 3.0 g of each sample is mixed with 150 g of standard natural rubber formula to form a circular test sample, and the minimum torque, maximum torque, vulcanization induction time and vulcanization time are tested at 150°C; the physical and mechanical performance test is performed by cutting the rubber test sample into a standard dumbbell-shaped test piece after vulcanization at 150°C to the vulcanization time, and testing the tensile strength and elongation at break of the test piece by using a universal tensile testing machine according to the national standard at a stretching rate of 500 mm / min; the environmental performance test is performed by analyzing the total amount of volatile organic compounds during vulcanization by using a headspace gas chromatography-mass spectrometry instrument after equilibration at 120°C for 30 min, and measuring the biodegradation rate of 50 mg of sample after incubation in a standard soil environment for 28 days.

[0031] Performance Test Results: Table 1 Performance Test Results Test item Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Thermal decomposition temperature (°C) 238 235 240 195 187 182 Scorch time (min, 125°C) 28.5 27.8 29.1 18.2 16.5 15.8 Optimum cure time (min, 150°C) 12.3 12.6 12.1 11.8 12.9 13.2 Tensile strength (MPa) 26.8 26.2 27.1 22.5 21.8 20.3 Elongation at break (%) 550 535 560 480 465 450 VOC emission (μg / g) 85 92 81 155 168 190 Biodegradability (28 days, %) 45 42 47 25 22 18 As can be seen from Table 1, examples 1-3 successfully solve the technical defects of traditional accelerators by introducing boron-nitrogen heterocyclic complex stabilizer and silane-based green dispersant. In terms of thermal stability, the thermal decomposition temperature of the example products reaches 235°C or above, which is about 50°C higher than that of the comparative product, which is due to the coordination structure formed by boron-nitrogen heterocycle and CBS molecule effectively inhibiting molecular chain rupture at high temperature. In terms of processing safety, the scorch time of the examples is extended to about 28 min, which is about 10 min higher than that of the comparative product, indicating that the synergistic effect of the modified compounds significantly delays the early vulcanization phenomenon. In terms of environmental performance, the VOC emission of the examples is reduced to below 100 μg / g, and the biodegradation rate is increased to more than 40%, which is half of the volatile organic compounds and twice the biodegradation rate of the comparative product. At the same time, on the basis of maintaining the appropriate curing time, the tensile strength of the vulcanized rubber of the examples is increased to more than 26 MPa, and the elongation at break is increased to more than 530%, proving that the new accelerator effectively improves the mechanical properties of the rubber products while improving the thermal stability and environmental performance. The performance of comparative examples 1 and 2 is significantly deteriorated when one of the modified compounds is missing, and the performance of comparative example 3 is at the lowest level when no modified compound is used, which fully verifies the irreplaceable synergistic effect of the two modified compounds in solving the problems of thermal stability and environmental performance.

[0032] The above examples only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as limiting the scope of the patent of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are within the scope of protection of the present application.

Claims

1. A high thermal stability environmentally friendly CBS characterized in that the steps of Comprise: S1, N-cyclohexyl-2-benzothiazole sulfonamide is dried in a vacuum drying oven at 78-82 DEG C; the dried N-cyclohexyl-2-benzothiazole sulfonamide is crushed and sieved to obtain pretreated N-cyclohexyl-2-benzothiazole sulfonamide powder; the pretreated N-cyclohexyl-2-benzothiazole sulfonamide powder is mixed with boron nitrogen heterocyclic complex stabilizer, silane-based green dispersant, dioctyl sebacate, calcium zinc stearate complex stabilizer and pentaerythritol tetra (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate) in a high-speed mixer to obtain a mixture; S2, the mixture is transferred to a twin-screw extruder for melt compounding; the extruder temperature is set as follows: zone 1 118-122 DEG C, zone 2 138-142 DEG C, zone 3 158-162 DEG C, zone 4 148-152 DEG C, and head 133-137 DEG C; the extruded melt material is cut into particles by underwater pelletizer, and the particles are cooled by cooling water tank to obtain cooled particles; the cooled particles are ultrafine pulverized under liquid nitrogen to obtain pulverized powder, and the pulverized powder is sieved.

2. The method for preparing high-thermal-stability environmentally friendly CBS according to claim 1, characterized in that, In step S1, the drying time in the vacuum drying oven at 78-82 DEG C is 4-6h.

3. The method for preparing high thermal stability environmentally friendly CBS according to claim 1, characterized in that, In step S2, the average residence time of the mixture in the extruder is 2-3min.

4. The method for preparing high thermal stability environmentally friendly CBS according to claim 1, characterized in that, The preparation method of the boron nitrogen heterocyclic complex stabilizer comprises: A1, under nitrogen protection, 2, 4, 6-trimethyl boron nitrogen cyclohexane and 3-tert-butyl-4-hydroxyphenyl propionic acid are dissolved in anhydrous tetrahydrofuran, and stirred until completely dissolved; triethylamine is added, and stirred at 50-55 DEG C to react, 9-borabicyclo [3.3.1] nonane is added, and refluxed at 50-55 DEG C to obtain a reaction mixture; the reaction mixture is cooled to room temperature, N-methyl pyrrolidone is added, and continued to react at 78-82 DEG C; A2, after the reaction is completed, a viscous liquid is obtained by reduced pressure distillation; a mixed solvent of deionized water and ethanol is added to the viscous liquid, and crystallized at 0-5 DEG C; white crystals are collected by filtration, and dried in a vacuum drying oven at 48-52 DEG C.

5. The method for preparing high thermal stability environmentally friendly CBS according to claim 4, characterized in that, In step A1, the reflux reaction time at 50-55 DEG C is 4-6h; the continued reaction time at 78-82 DEG C is 6-8h.

6. The method for preparing high thermal stability environmentally friendly CBS according to claim 4, characterized in that, In step A2, the crystallization time at 0-5 DEG C is 12-14h.

7. The method for preparing high thermal stability environmentally friendly CBS according to claim 1, characterized in that, The preparation method of the silane-based green dispersant comprises: B1, 3-isocyanate propyl triethoxysilane and polyethylene glycol monomethyl ether are dissolved in toluene, dibutyltin dilaurate is added, and refluxed at 84-86 DEG C to obtain a silane-based polyurethane prepolymer solution; glycidyl methacrylate and 2, 2, 6, 6-tetramethylpiperidine-1-oxyl radical are added, and reacted at 110-115 DEG C; B2, after the reaction is completed, the system is cooled to room temperature; a viscous liquid is obtained by reduced pressure distillation; n-hexane is added to the viscous liquid, and white solid is obtained after filtration; the white solid is dried in a vacuum drying oven at 38-42 DEG C.

8. The method for preparing high thermal stability environmentally friendly CBS according to claim 7, characterized in that, In step B1, the reaction time is 5-7 h at 84-86 °C and 3-5 h at 110-115 °C.

9. The method for preparing high thermal stability environmentally friendly CBS according to claim 7, characterized in that, In step B2, the drying time is 6-8 h in a vacuum drying oven at 38-42 °C.

10. A high thermal stability environmentally friendly CBS, characterized in that, The high-thermal-stability environmentally-friendly CBS is prepared according to the method of any one of claims 1-9.