Anti-aging rubber material and preparation method thereof

Abstract

The invention relates to an anti-aging rubber material and a preparation method thereof, and belongs to the technical field of rubber materials. The anti-aging rubber material comprises the following components: nitrile rubber, carbon black, modified calcium carbonate, a plasticizer, a lubricant, an accelerant, a composite antioxidant, other auxiliaries and a vulcanizing agent. The rubber material prepared by the invention can still keep high-level key mechanical property indexes such as tensile strength and elongation at break in severe aging environments such as high temperature and strong ultraviolet radiation, has good performance stability, and can better adapt to application scenes such as automobile parts, outdoor building materials, industrial sealing elements and the like with high durability requirements.

Description

Technical Field

[0001] This invention belongs to the technical field of rubber materials, and relates to an aging-resistant rubber material and its preparation method. Background Technology

[0002] Rubber materials, with their excellent elasticity, wear resistance, and good processing properties, are widely used in many key fields such as industrial sealing, transportation, and outdoor products. However, in long-term practical use, conventional rubber materials are susceptible to the combined effects of various environmental factors such as heat, oxygen, and ultraviolet radiation, leading to a gradual decrease in their mechanical properties, surface aging, and even cracking, thus significantly shortening the service life of the products. This makes it difficult for traditional rubber to meet the application requirements under extreme conditions such as high temperature and strong ultraviolet radiation.

[0003] Currently, conventional methods for improving the anti-aging properties of rubber materials largely rely on adding synthetic antioxidants. However, these antioxidants generally suffer from drawbacks such as high migration and short-lived effects, and some synthetic antioxidants are also environmentally unfriendly. Tannic acid, as a natural polyphenol, contains a large number of phenolic hydroxyl groups in its molecular structure, exhibiting excellent free radical quenching capabilities and showing significant potential in resisting thermo-oxidative and UV aging, making it one of the preferred natural antioxidants. However, when tannic acid is directly added to the rubber matrix, its strong hydrophilicity and poor compatibility with the rubber matrix easily lead to aggregation, preventing it from fully exerting its anti-aging effect. Summary of the Invention

[0004] The purpose of this invention is to provide an aging-resistant rubber material and its preparation method. The rubber material prepared by this invention maintains high levels of key mechanical properties such as tensile strength and elongation at break even under harsh aging environments such as high temperature and strong ultraviolet radiation, demonstrating good performance stability. Compared with conventional rubber materials, this material has a significantly longer service life and is better suited for applications requiring high durability, such as automotive parts, outdoor building materials, and industrial seals.

[0005] The objective of this invention can be achieved through the following technical solutions: An aging-resistant rubber material comprises the following components in parts by weight: The ingredients are: 90-110 parts nitrile rubber, 50-60 parts carbon black, 16.0-20.0 parts modified calcium carbonate, 9.0-12.0 parts plasticizer, 2-4 parts lubricant, 1.0-2.0 parts accelerator, 3-4 parts composite antioxidant, 4-6 parts other additives, and 1.0-2.0 parts vulcanizing agent.

[0006] As a preferred embodiment of the present invention, the nitrile rubber is of type NANCAR. ®1052, with an acrylonitrile content of 33%, and the plasticizer is dioctyl phthalate.

[0007] As a preferred embodiment of the present invention, the lubricant is a compound of oleic acid amide and polyethylene wax in a mass ratio of 3:1-2.

[0008] As a preferred embodiment of the present invention, the accelerator is accelerator NS.

[0009] As a preferred embodiment of the present invention, the composite antioxidant is a mixture of antioxidant RD and stabilizing antioxidant in a mass ratio of 1:3. Antioxidant RD, as a commonly used amine antioxidant, has a significant inhibitory effect on the thermo-oxidative aging of rubber. During rubber processing and use, it can effectively capture free radicals and delay the aging and degradation of molecular chains.

[0010] As a preferred embodiment of the present invention, the other additives are a compound of magnesium oxide and zinc stearate in a mass ratio of 3:1.

[0011] In a preferred embodiment of the present invention, the vulcanizing agent is sulfur.

[0012] As a preferred embodiment of the present invention, the modified calcium carbonate is calcium carbonate modified with silane coupling agent KH-550, with a grafting rate of 1.5%.

[0013] As a preferred embodiment of the present invention, the preparation of the stabilized antioxidant includes the following steps: S1. Place the epoxy monomer, cashew phenol and organic solvent in a reactor, start stirring, slowly add tannic acid and continue stirring, introduce inert gas, preheat and then add catalyst and stir to mix, heat and stir, and then evaporate to obtain the preform. S2. Heat and mix the preform and solvent, add zinc-aluminum mixture while stirring, adjust the pH value with alkaline solution, stir at constant temperature, cool, filter, wash, and place in a vacuum drying oven to obtain a stable oxidant.

[0014] As a preferred technical solution of the present invention, the stirring speed in step S1 is 300-400 rpm, the temperature is 45-50℃, the stirring time is 20-30 min, and the stirring time is 30-40 min.

[0015] As a preferred embodiment of the present invention, the inert gas in step S1 is nitrogen gas, the catalyst is added for 10-15 minutes, the stirring temperature is 45-50°C, the stirring speed is 400-500 rpm, and the stirring time is 30-40 minutes.

[0016] As a preferred technical solution of the present invention, the heating and stirring in step S1 is to stir at 60-65℃ and 500-600℃ for 1.5-2.0h, and then stir at 70-75℃ for 2-3h.

[0017] As a preferred embodiment of the present invention, in step S1, the mass ratio of epoxy monomer, cashew phenol, tannic acid, catalyst and organic solvent is 50-55: 5-6: 45-48: 180-200: 1.2-1.5, wherein the organic solvent is anhydrous DMF, the catalyst is triethylamine, and the epoxy monomer is triglycidyl-p-aminophenol.

[0018] As a preferred technical solution of the present invention, tannic acid, as a polyphenolic compound, contains a large number of phenolic hydroxyl groups in its molecule, which can achieve antioxidant effect by capturing free radicals generated during rubber aging and blocking the oxidation chain reaction.

[0019] As a preferred embodiment of the present invention, the mass ratio of the preform, zinc-aluminum mixture and solvent in step S2 is 9.5-10:22-23:6-8, the solvent is anhydrous ethanol, and the zinc-aluminum mixture is composed of zinc nitrate, aluminum nitrate and deionized water in a mass ratio of 12.5-13.0:11.5-11.8:200-220.

[0020] As a preferred technical solution of the present invention, the heating and mixing temperature in step S2 is 45-50℃, the rotation speed is 400-500rpm, and the stirring time is 15-20min. The stirring state is a temperature of 50-58℃ and a stirring speed of 500-600rpm.

[0021] As a preferred embodiment of the present invention, the zinc-aluminum mixture in step S2 is added at a rate of 2 mL / min, the pH value of the alkaline solution is adjusted to 9.0-10.0 using a 10 wt% sodium hydroxide aqueous solution, and the constant temperature stirring is 60-65°C for 2-3 hours.

[0022] As a preferred embodiment of the present invention, the cooling in step S2 is cooling to room temperature, the washing is washing with deionized water until the washing liquid is neutral, and the vacuum drying temperature is 80-90℃ and the vacuum drying time is 4-5h.

[0023] As a preferred embodiment of the present invention, a method for preparing an aging-resistant rubber material includes the following steps: Nitrile rubber is put into a mixer and heated to 80°C at 60 rpm for 12 minutes. Then carbon black, modified calcium carbonate, lubricant, plasticizer, accelerator, composite antioxidant and other additives are added in sequence. The mixture is heated to 120°C and mixed for another 10 minutes. Finally, vulcanizing agent is added and the mixture is kept at 120°C for another 15 minutes before being discharged to obtain the aging-resistant rubber material.

[0024] The beneficial effects of this invention are: The rubber material prepared by this invention exhibits excellent resistance to thermo-oxidative aging and ultraviolet aging. Under harsh aging conditions such as continuous high temperatures and strong ultraviolet radiation, its key mechanical properties, such as tensile strength and elongation at break, remain at a high level, demonstrating good performance stability. Compared to conventional rubber materials, this material has a significantly extended service life, making it more effectively suited for applications requiring high material durability, such as automotive parts, outdoor building materials, and industrial seals. Detailed Implementation

[0025] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0026] Example 1 An aging-resistant rubber material comprises the following components in parts by weight: The composition includes 90 parts of nitrile rubber, 50 parts of carbon black, 16.0 parts of modified calcium carbonate, 9.0 parts of plasticizer, 2 parts of lubricant, 1.0 part of accelerator, 3 parts of composite antioxidant, 4 parts of other additives, and 1.0 part of vulcanizing agent. The plasticizer is dioctyl phthalate; The lubricant is a compound of oleic acid amide and polyethylene wax in a mass ratio of 3:1; The accelerator is accelerator NS; The composite antioxidant is a mixture of antioxidant RD and stabilized antioxidant in a mass ratio of 1:3; The other additives are a compound of magnesium oxide and zinc stearate in a mass ratio of 3:1; The vulcanizing agent is sulfur.

[0027] The preparation of the stabilized antioxidant includes the following steps: S1. Place the epoxy monomer, cashew phenol and organic solvent in a reactor, stir at 300 rpm and 45°C for 20 min, slowly add tannic acid and continue stirring for 30 min, introduce nitrogen gas, preheat to 45°C, add catalyst, stir at 45°C and 400 rpm for 30 min, stir at 60°C and 500°C for 1.5 h, raise the temperature to 70°C and stir for 2 h, and rotary evaporate to obtain the preform; The mass ratio of epoxy monomer, cashew phenol, tannic acid, catalyst and organic solvent is 50:5:45:180:1.2, wherein the organic solvent is anhydrous DMF, the catalyst is triethylamine, and the epoxy monomer is triglycidyl-p-aminophenol. S2. The preform and solvent were stirred at 45℃ and 400 rpm for 15 min. The zinc-aluminum mixture was then added at a rate of 2 mL / min while stirring at 50℃ and 500 rpm. The pH was then adjusted to 9.0 with a 10 wt% sodium hydroxide aqueous solution. The mixture was stirred at 60℃ for 2 h. After cooling to room temperature, the solid was filtered and washed with deionized water until the washing solution was neutral. The solid was then placed in a vacuum drying oven and dried under vacuum at 80℃ for 4 h to obtain a stable oxidant.

[0028] The mass ratio of the preform, zinc-aluminum mixture, and solvent is 9.5:22:6, the solvent is anhydrous ethanol, and the zinc-aluminum mixture is composed of zinc nitrate, aluminum nitrate, and deionized water in a mass ratio of 12.5:11.5:200.

[0029] The preparation of an aging-resistant rubber material includes the following steps: Nitrile rubber is put into a mixer and heated to 80°C at 60 rpm for 12 minutes. Then carbon black, modified calcium carbonate, lubricant, plasticizer, accelerator, composite antioxidant and other additives are added in sequence. The mixture is heated to 120°C and mixed for another 10 minutes. Finally, vulcanizing agent is added and the mixture is kept at 120°C for another 15 minutes before being discharged to obtain the aging-resistant rubber material.

[0030] Example 2 An aging-resistant rubber material comprises the following components in parts by weight: The ingredients are: 100 parts nitrile rubber, 55 parts carbon black, 18 parts modified calcium carbonate, 10.5 parts plasticizer, 3 parts lubricant, 1.5 parts accelerator, 3.5 parts composite antioxidant, 5 parts other additives, and 1.5 parts vulcanizing agent. The plasticizer is dioctyl phthalate; The lubricant is a compound of oleic acid amide and polyethylene wax in a mass ratio of 3:1.5; The accelerator is accelerator NS; The composite antioxidant is a mixture of antioxidant RD and stabilized antioxidant in a mass ratio of 1:3; The other additives are a compound of magnesium oxide and zinc stearate in a mass ratio of 3:1; The vulcanizing agent is sulfur.

[0031] The preparation of the stabilized antioxidant includes the following steps: S1. Place epoxy monomer, cashew phenol and organic solvent in a reactor, stir at 350 rpm and 48°C for 25 min, slowly add tannic acid and continue stirring for 35 min, introduce nitrogen gas, preheat to 48°C, add catalyst and stir at 48°C and 450 rpm for 35 min, stir at 62°C and 550°C for 1.8 h, raise the temperature to 72°C and stir for 2.5 h, rotary evaporate to obtain the preform; The mass ratio of epoxy monomer, cashew phenol, tannic acid, catalyst and organic solvent is 52:5.5:46:190:1.4, wherein the organic solvent is anhydrous DMF, the catalyst is triethylamine, and the epoxy monomer is triglycidyl-p-aminophenol. S2. The preform and solvent were stirred at 48℃ and 450 rpm for 18 min. The zinc-aluminum mixture was then added at a rate of 2 mL / min while stirring at 54℃ and 550 rpm. The pH was then adjusted to 9.5 with a 10 wt% sodium hydroxide aqueous solution. The mixture was stirred at 62℃ for 2.5 h. After cooling to room temperature, the solid was filtered and washed with deionized water until the washing solution was neutral. The solid was then placed in a vacuum drying oven and dried under vacuum at 85℃ for 4.5 h to obtain a stable oxidant.

[0032] The mass ratio of the preform, zinc-aluminum mixture, and solvent is 9.8:22.5:7, the solvent is anhydrous ethanol, and the zinc-aluminum mixture is composed of zinc nitrate, aluminum nitrate, and deionized water in a mass ratio of 12.8:11.6:210.

[0033] The preparation of an aging-resistant rubber material includes the following steps: Nitrile rubber is put into a mixer and heated to 80°C at 60 rpm for 12 minutes. Then carbon black, modified calcium carbonate, lubricant, plasticizer, accelerator, composite antioxidant and other additives are added in sequence. The mixture is heated to 120°C and mixed for another 10 minutes. Finally, vulcanizing agent is added and the mixture is kept at 120°C for another 15 minutes before being discharged to obtain the aging-resistant rubber material.

[0034] Example 3 An aging-resistant rubber material comprises the following components in parts by weight: The composition includes 110 parts of nitrile rubber, 60 parts of carbon black, 20.0 parts of modified calcium carbonate, 12.0 parts of plasticizer, 4 parts of lubricant, 2.0 parts of accelerator, 4 parts of composite antioxidant, 6 parts of other additives, and 2.0 parts of vulcanizing agent. The plasticizer is dioctyl phthalate; The lubricant is a compound of oleic acid amide and polyethylene wax in a mass ratio of 3:2; The accelerator is accelerator NS; The composite antioxidant is a mixture of antioxidant RD and stabilized antioxidant in a mass ratio of 1:3; The other additives are a compound of magnesium oxide and zinc stearate in a mass ratio of 3:1; The vulcanizing agent is sulfur.

[0035] The preparation of the stabilized antioxidant includes the following steps: S1. Place epoxy monomer, cashew phenol and organic solvent in a reactor, stir at 400 rpm and 50°C for 30 min, slowly add tannic acid and continue stirring for 40 min, introduce nitrogen gas, preheat to 50°C, add catalyst and stir at 50°C and 500 rpm for 40 min, stir at 65°C and 600°C for 2.0 h, raise the temperature to 75°C and stir for 3 h, and rotary evaporate to obtain the preform; The mass ratio of epoxy monomer, cashew phenol, tannic acid, catalyst and organic solvent is 55:6:48:200:1.5, wherein the organic solvent is anhydrous DMF, the catalyst is triethylamine, and the epoxy monomer is triglycidyl-p-aminophenol. S2. The preform and solvent were stirred at 50°C and 500 rpm for 20 min. Then, the zinc-aluminum mixture was added at 58°C and 600 rpm with stirring. The pH was adjusted to 10.0 with 10 wt% sodium hydroxide aqueous solution. The mixture was stirred at 65°C for 3 h. After cooling to room temperature, the solid was filtered and washed with deionized water until the washing solution was neutral. The solid was then placed in a vacuum drying oven and dried under vacuum at 90°C for 5 h to obtain a stable oxidant.

[0036] The mass ratio of the preform, zinc-aluminum mixture, and solvent is 10:23:8, the solvent is anhydrous ethanol, and the zinc-aluminum mixture is composed of zinc nitrate, aluminum nitrate, and deionized water in a mass ratio of 13.0:11.8:220.

[0037] The preparation of an aging-resistant rubber material includes the following steps: Nitrile rubber is put into a mixer and heated to 80°C at 60 rpm for 12 minutes. Then carbon black, modified calcium carbonate, lubricant, plasticizer, accelerator, composite antioxidant and other additives are added in sequence. The mixture is heated to 120°C and mixed for another 10 minutes. Finally, vulcanizing agent is added and the mixture is kept at 120°C for another 15 minutes before being discharged to obtain the aging-resistant rubber material.

[0038] Comparative Example 1 Compared with Example 3, the difference is that tannic acid was used instead of the preform in Comparative Example 1, but everything else is the same.

[0039] Comparative Example 2 Compared with Example 3, the difference is that cashew phenol was used instead of tannic acid in Comparative Example 2, but everything else is the same.

[0040] Comparative Example 3 Compared with Example 3, the difference is that Tannic acid was used instead of cashew phenol in Comparative Example 3, but everything else is the same.

[0041] Comparative Example 4 Compared with Example 3, Comparative Example 4 differs in step S2; S2. The solvent was stirred at 50°C and 500 rpm for 20 min. Then, the zinc-aluminum mixture was added at 58°C and 600 rpm with stirring. The pH was adjusted to 10.0 with 10 wt% sodium hydroxide aqueous solution. The mixture was stirred at 65°C for 3 h. After cooling to room temperature, the solid was filtered and washed with deionized water until the washing solution was neutral. The solid was then placed in a vacuum drying oven and dried under vacuum at 90°C for 5 h. After mixing with the preform, the stable oxidant was obtained.

[0042] Everything else is the same.

[0043] Comparative Example 5 Compared with Example 3, the difference is that Comparative Example 5 uses calcium carbonate instead of modified calcium carbonate, otherwise they are the same.

[0044] The rubber materials obtained in Examples 1-3 and Comparative Examples 1-5 were subjected to mechanical tests according to GB / T 528-2009 before and after baking at 100℃ for 72 hours according to GB / T 3512-2014, and the mechanical strength before and after baking was recorded.

[0045] UV aging test: Tensile strength and elongation at break were tested according to GB / T 528-2009 standard using UVB313 ultraviolet lamps with an irradiance of 0.58W / cm2, a power of 40W, a temperature of 60℃, a relative humidity of 60%, and an aging time of 500h. Tensile strength was measured again afterward.

[0046] The test results are shown in Table 1.

[0047] Table 1 Sample performance test results

[0048] As can be seen from the test results in Table 1, compared with Comparative Examples 1-5, the rubber materials prepared by the present invention have excellent aging resistance.

[0049] This invention grafts tannic acid onto the molecular chain by chemically bonding the epoxy group in the triglycidyl-p-aminophenol molecule with the phenolic hydroxyl group of tannic acid. Simultaneously, cashew nut shell extract is introduced as a synergistic modifier. Its active phenolic hydroxyl group undergoes a ring-opening reaction with the epoxy group, forming a ternary grafted structure of epoxy monomer / tannic acid / cashew nut shell extract. Furthermore, the carbon-carbon double bond of cashew nut shell extract can exert multiple synergistic effects. The carbon-carbon double bond can crosslink with the rubber molecular chain during rubber vulcanization, in conjunction with C... 15 The physical entanglement of long-chain hydrocarbon groups reduces the surface energy of the grafted product, improves the dispersion compatibility of tannic acid in the rubber matrix, avoids agglomeration failure, strengthens the bonding strength between antioxidants and the rubber matrix, and prolongs the action period.

[0050] Zinc and aluminum ions hydrolyze under alkaline conditions to form zinc-aluminum layered bimetallic hydroxides, which are in situ coated on the surface of the preform to form a core-shell structure. The long chain of cashew phenol is interwoven between the layers to increase the interlayer spacing. The carbon-carbon double bond of cashew phenol can participate in the chemical reaction of the system, significantly enhancing the interfacial bonding force between the preform and the shell in the system. This not only improves thermal stability and strengthens free radical quenching and adsorption of aging products, but also achieves the slow release of active ingredients, further optimizing the dispersion compatibility and binding strength of the stabilizing oxidant in the system.

[0051] After surface modification, the surface energy of modified calcium carbonate is reduced, allowing it to disperse uniformly in the rubber matrix. It delays thermo-oxidative aging through physical barrier effects and synergistically complements composite antioxidants to provide reinforcement. The long-chain cashew phenol enhances the interfacial adhesion between the rubber matrix and the modified calcium carbonate, while the carbon-carbon double bonds promote interfacial chemical reactions. Combined with the flexible characteristics of the long chains, it reduces internal stress within the matrix, minimizing the breakage and cross-linking of rubber molecular chains during aging, thus synergistically maintaining the stability of material properties.

[0052] 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-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any indirect 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. An aging-resistant rubber material, characterized in that, The following components are included by weight: The ingredients are: 90-110 parts nitrile rubber, 50-60 parts carbon black, 16.0-20.0 parts modified calcium carbonate, 9.0-12.0 parts plasticizer, 2-4 parts lubricant, 1.0-2.0 parts accelerator, 3-4 parts composite antioxidant, 4-6 parts other additives, and 1.0-2.0 parts vulcanizing agent; The preparation of the stabilized antioxidant includes the following steps: S1. Place the epoxy monomer, cashew phenol and organic solvent in a reactor, start stirring, slowly add tannic acid and continue stirring, introduce inert gas, preheat and then add catalyst and stir to mix, heat and stir, and then evaporate to obtain the preform. S2. Heat and mix the preform and solvent, add zinc-aluminum mixture while stirring, adjust the pH value with alkaline solution, stir at constant temperature, cool, filter, wash, and place in a vacuum drying oven to obtain a stable oxidant.

2. The aging-resistant rubber material according to claim 1, characterized in that: The lubricant is a compound of oleamide and polyethylene wax, and the composite antioxidant is a compound of antioxidant RD and stabilized antioxidant in a mass ratio of 1:

3.

3. The aging-resistant rubber material according to claim 1, characterized in that: The other additives are a compound of magnesium oxide and zinc stearate in a mass ratio of 3:1, and the vulcanizing agent is sulfur.

4. The aging-resistant rubber material according to claim 1, characterized in that: The catalyst is added in step S1 for 10-15 minutes, and the heating and stirring are carried out at 60-65℃ and 500-600℃ for 1.5-2.0 hours, and then heated to 70-75℃ and stirred for 2-3 hours.

5. The aging-resistant rubber material according to claim 1, characterized in that: In step S1, the mass ratio of epoxy monomer, cashew phenol, tannic acid, catalyst and organic solvent is 50-55: 5-6: 45-48: 180-200: 1.2-1.5, and the epoxy monomer is triglycidyl-p-aminophenol.

6. The aging-resistant rubber material according to claim 1, characterized in that: In step S2, the mass ratio of the preform, zinc-aluminum mixture, and solvent is 9.5-10:22-23:6-8. The zinc-aluminum mixture is composed of zinc nitrate, aluminum nitrate, and deionized water in a mass ratio of 12.5-13.0:11.5-11.8:200-220.

7. The aging-resistant rubber material according to claim 1, characterized in that: The zinc-aluminum mixture in step S2 is added at a rate of 2 mL / min.

8. The aging-resistant rubber material according to claim 1, characterized in that: The temperature of the constant temperature stirring in step S2 is 60-65℃, the stirring time is 2-3h, and the cooling is cooling to room temperature.

9. A method for preparing an aging-resistant rubber material as described in any one of claims 1 to 8, characterized in that, The preparation method includes the following steps: nitrile rubber is put into a mixer for mixing, and then carbon black, modified calcium carbonate, lubricant, plasticizer, accelerator, composite antioxidant and other additives are added in sequence. After heating, the mixture is continued to be mixed, and then vulcanizing agent is added and the mixture is continued to be mixed before discharge, thus obtaining the aging-resistant rubber material.

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