Preparation method of low-zinc high-efficiency composite active agent for blended rubber

Abstract

The invention relates to the technical field of low-zinc composite active agents, in particular to a low-zinc efficient composite active agent for blended rubber and a preparation method thereof.The preparation method comprises the following steps that zinc acetate, zinc nitrate, zinc sulfate and urea are mixed to prepare nano-zinc oxide, and the nano-zinc oxide is modified with polypropylene glycol to obtain modified nano-zinc oxide; mixing and stirring a dispersing agent, stearic acid, modified nano zinc oxide, multi-walled carbon nanotubes and magnesium oxide under the protection of inert gas to prepare a blend, and curing and molding the blend through a condensation granulation process to obtain the low-zinc high-efficiency composite activator for blended rubber. The prepared low-zinc efficient composite active agent for the blended rubber shortens the vulcanization time of the blended rubber, is excellent in dispersity and enhances the mechanical properties, including tensile strength and elongation at break, of the blended rubber, and in addition, the preparation method is simple and convenient to operate and low in cost and has a good industrial application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of low-zinc composite activators, in particular to a low-zinc high-efficiency composite activator for blended rubber and a preparation method thereof. Background Art

[0002] As an important industrial raw material, rubber is widely used in aviation, petroleum, automobile, chemical and other fields. With the rapid development of the domestic rubber industry, the market demand for rubber continues to rise, which in turn puts higher requirements on rubber additives - as an indispensable basic element in the molding process of polymer products, although the amount of additives added to the formula is small, it plays a decisive role in improving the processing performance and application performance of the products. The rubber additive industry is an important supporting industry for the rubber industry. Rubber products in different application fields have significant differences in performance requirements, and the required additives are also different. Taking tire rubber products as an example, its vulcanization system is mainly composed of sulfur, accelerators and activators. Among them, the activator is a key additive that directly affects the vulcanization rate, crosslinking density and final mechanical properties of the rubber compound.

[0003] To further enhance the overall performance of rubber, rubber blending technology has emerged. By blending different types of rubber or rubber with polymers like plastics to create composite rubber, the performance limitations of individual rubbers can be significantly improved, complementing each other's performance and developing materials with superior overall performance. During this process, various additives, such as vulcanizers, activators, accelerators, crosslinkers, plasticizers, and antioxidants, are added to stabilize and optimize the properties of the composite rubber. The enhancement function of these additives is crucial for improving the quality of the blended rubber.

[0004] Vulcanization activators, a special type of activation-accelerating additive, can improve crosslinking efficiency by increasing accelerator activity, reducing accelerator dosage, and shortening vulcanization time. In traditional processes, zinc oxide is a commonly used vulcanization activator, providing not only activation but also reinforcement and compatibility. However, the zinc released during the production, use, and recycling of rubber products can pose a threat to the environment and human health, leading to the development of low- or no-zinc activators. Research has shown that nano-zinc oxide, due to its small particle size, large specific surface area, and strong adsorption capacity, can reduce zinc oxide dosage while maintaining high activity, which is of great significance for conserving zinc resources and protecting the environment. However, for blended rubber, the distribution of vulcanization accelerators in the blend is affected by their solubility in each phase (two- or three-phase). This solubility difference directly leads to uneven dispersion of nano-zinc oxide in the different rubber phases, which in turn affects the vulcanization performance of the blend. Experiments have shown that further reducing the nano-zinc oxide dosage can also lead to a decline in the mechanical properties of the blended rubber, especially in systems with reclaimed rubber with poor compatibility. Therefore, the development of a low-zinc, high-efficiency composite activator that shortens the vulcanization time, has excellent dispersibility, significant reinforcement effect, and is suitable for blended rubber has significant social benefits and economic value. Summary of the Invention

[0005] The object of the present invention is to provide a low-zinc, high-efficiency composite activator for blended rubber and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] Step 1: Mix zinc acetate, zinc nitrate, zinc sulfate and urea, add distilled water, stir until completely dissolved and then heat to react; after the reaction is completed, cool and filter, wash the obtained solid with ammonia water and anhydrous ethanol in sequence, filter and dry; grind the dried product and calcine to obtain nano zinc oxide;

[0008] Step 2: Mixing nano zinc oxide and distilled water, and ultrasonically stirring to obtain a nano zinc oxide suspension; mixing and dissolving polypropylene glycol and distilled water, and then adding the mixture to the nano zinc oxide suspension and stirring; collecting particles by centrifugation, washing with distilled water, and drying to obtain modified nano zinc oxide;

[0009] Step 3: Under the protection of inert gas, the dispersant, stearic acid, modified nano zinc oxide, multi-walled carbon nanotubes and magnesium oxide are mixed and stirred to form a blend;

[0010] Step 4: The blend is solidified and formed through a condensation granulation process to obtain a low-zinc and high-efficiency composite active agent for blended rubber.

[0011] Furthermore, the zinc acetate, zinc nitrate, zinc sulfate and urea are mixed in a mass ratio of 1:2:5:30.

[0012] Furthermore, the nano zinc oxide and distilled water in step 2 are mixed at a mass ratio of 1:4, and the polypropylene glycol and distilled water are mixed at a mass ratio of 1:80.

[0013] Furthermore, the inert gas is one of nitrogen, helium and carbon dioxide.

[0014] Furthermore, the inert gas is nitrogen.

[0015] Furthermore, the dispersant is sodium dodecyl sulfate.

[0016] Furthermore, the dispersant, stearic acid, modified nano zinc oxide, multi-walled carbon nanotubes and magnesium oxide are mixed in a mass ratio of 6:5:1:1:3.

[0017] In the above technical solution, sodium dodecyl sulfate as a dispersant can reduce the agglomeration of nano-zinc oxide; stearic acid as a surface modifier can enhance the interfacial compatibility between the low-zinc and high-efficiency composite active agent for the blended rubber and the blended rubber; the addition of magnesium oxide maintains the pH of the blend in the weakly alkaline range, and acts as a desiccant to absorb residual moisture during the condensation granulation process, thereby improving the storage stability of the finished product.

[0018] Furthermore, the multi-walled carbon nanotubes are modified, and the specific modification steps are as follows:

[0019] Multi-walled carbon nanotubes were weighed and prepared into a 1% by mass aqueous solution, which was then dispersed by ultrasonic treatment. Sericin was immersed in the aqueous solution and magnetically stirred at a constant temperature to obtain a mixed system. The mixed system was further ultrasonically treated to obtain modified multi-walled carbon nanotubes.

[0020] Furthermore, the multi-walled carbon nanotubes have a diameter of 8 to 10 nm and a length of 50 to 100 μm; the mass ratio of sericin to the multi-walled carbon nanotube aqueous solution is 10:3; and the magnetic stirring conditions are 45 to 50° C. and stirring for 30 to 35 minutes.

[0021] Furthermore, the heating reaction conditions in step 1 are a heating temperature of 90-100°C, a reaction time of 2-3 hours, and a calcination condition of 450-500°C for 2-2.5 hours; the ultrasonic stirring conditions in step 2 are a frequency of 50-60 Hz, a time of 30-35 minutes, and a stirring condition after adding a mixture of polypropylene glycol and distilled water at 20-25°C for 20-24 hours; and the stirring conditions in step 3 are stirring at a speed of 900-1300 rpm for 15-30 minutes.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention describes a low-zinc, high-efficiency composite active agent for blended rubber and a preparation method thereof. A dispersant, stearic acid, modified nano-zinc oxide, multi-walled carbon nanotubes, and magnesium oxide are mixed and stirred under inert gas protection to prepare a blend. The blend is solidified and formed through a condensation granulation process to obtain a low-zinc, high-efficiency composite active agent for blended rubber, which shortens the vulcanization time of the blended rubber, has excellent dispersibility, and enhances the mechanical properties of the blended rubber, including tensile strength and elongation at break.

[0024] 2. This invention describes a low-zinc, high-efficiency composite active agent for rubber blends and its preparation method. Nano-zinc oxide is surface-modified with polypropylene glycol. By creating hydrogen bonding interactions, the nano-zinc oxide achieves efficient dispersion and activity retention within the blended rubber matrix. The modified nano-zinc oxide exhibits three significant advantages: First, in terms of dispersion performance, the modified nano-zinc oxide achieves uniform distribution within the blended rubber matrix and significantly enhances interfacial compatibility with the rubber matrix, forming a stable bonding structure. This excellent dispersibility lays the foundation for subsequent performance improvements. Second, in terms of vulcanization performance, the modified nano-zinc oxide exhibits a dual effect: on the one hand, it maintains high activity during the vulcanization process through hydrogen bonding, and on the other hand, it significantly accelerates the vulcanization reaction. This characteristic allows the modified nano-zinc oxide to achieve the same vulcanization performance as traditional zinc oxide with only a small addition, effectively solving the problem of reduced mechanical properties associated with low zinc content. Finally, from an environmental perspective, by reducing zinc usage (reducing resource consumption) and inhibiting zinc release (reducing environmental pollution), it effectively mitigates potential hazards to aquatic ecosystems and human health, providing an innovative solution for the sustainable development of the rubber industry.

[0025] 3. This invention describes a low-zinc, high-efficiency composite active agent for rubber blends and its preparation method. Multi-walled carbon nanotubes modified with sericin increase their hydrophilic functional groups, promoting the dispersion of nano-zinc oxide in the rubber blend matrix. The -NH2 in the sericin forms weak hydrogen bonds with the ether bonds of polypropylene glycol, improving the interfacial bonding between the nano-zinc oxide and the rubber blend. Furthermore, the polypropylene glycol-modified nano-zinc oxide provides an efficient zinc source for vulcanization activation, while the sericin-modified multi-walled carbon nanotubes stabilize the vulcanization intermediates through polar groups. The synergistic effect of these two agents shortens the vulcanization time. DETAILED DESCRIPTION

[0026] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0027] In the following specific embodiments,

[0028] Zinc acetate: Product No. S48372, from Shanghai Yuanye Biotechnology Co., Ltd.

[0029] Zinc sulfate: Product No. S22124, from Shanghai Yuanye Biotechnology Co., Ltd.

[0030] Urea: Product No. WKQ-0002053, sourced from Chengdu Chaojiuba Biotechnology Co., Ltd.

[0031] Ammonia: Product No. R20788, from Shanghai Yuanye Biotechnology Co., Ltd.

[0032] Anhydrous ethanol: Product No. C0691510075, from Nanjing Chemical Reagent Co., Ltd.

[0033] Polypropylene glycol: Product No. A00281, sourced from Wuhan Jiyesheng Chemical Co., Ltd.

[0034] Nitrogen: from Shenzhen Yuejia Gas Co., Ltd.;

[0035] Sodium dodecyl sulfate: Product No. S15013, from Shanghai Yuanye Biotechnology Co., Ltd.

[0036] Stearic acid: Product No. S30473, from Shanghai Yuanye Biotechnology Co., Ltd.

[0037] Multi-walled carbon nanotubes: Product No. A068566, sourced from Zhengzhou Huiju Chemical Co., Ltd.

[0038] Magnesium oxide: Product No. XM-2, sourced from Qinghai Western Magnesium Co., Ltd.

[0039] Sericin: Product No. A650886, sourced from Zhengzhou Huiju Chemical Co., Ltd.

[0040] Natural rubber: Product No. JS1634, sourced from Hubei Jusheng Technology Co., Ltd.

[0041] Butadiene rubber: Product No. QF3802, sourced from Hubei Qifei Pharmaceutical Chemical Co., Ltd.

[0042] Styrene-butadiene rubber: Product No. XK0332, sourced from Hubei Xinkang Pharmaceutical Chemical Co., Ltd.

[0043] Silica: 1500 mesh, product number T25658, from Shanghai Yuanye Biotechnology Co., Ltd.

[0044] Accelerator: Accelerator DM, product number S41468, from Shanghai Yuanye Biotechnology Co., Ltd.

[0045] Antioxidant: Antioxidant RD, product number LI3606, comes from Hubei Xinhongli Chemical Co., Ltd.

[0046] Example 1: A low-zinc, high-efficiency composite active agent for blended rubber and a preparation method thereof, comprising the following steps:

[0047] Step 1: 1g zinc acetate, 2g zinc nitrate, 5g zinc sulfate and 30g urea were mixed, 100mL distilled water was added, and the mixture was stirred until completely dissolved, and then heated to 90°C and kept warm for 2h. After the reaction was completed, the mixture was cooled to 20°C and filtered. The obtained solid was washed with ammonia water and anhydrous ethanol in sequence to remove residual impurities. After washing, the mixture was filtered and dried in a vacuum drying oven for 24h. The dried product was ground to make it fine and uniform, and calcined at 450°C for 2h to obtain nano zinc oxide.

[0048] Step 2: 25 g of nano-zinc oxide and 100 mL of distilled water were mixed and stirred at an ultrasonic frequency of 50 Hz for 30 minutes to obtain a nano-zinc oxide suspension; 1.25 g of polypropylene glycol was mixed and dissolved in 100 mL of distilled water and then added to the nano-zinc oxide suspension, and stirred at 20° C. for 20 hours; the particles were collected by centrifugation, washed with distilled water, and dried at 100° C. for 6 hours to obtain modified nano-zinc oxide;

[0049] Step 3: Under nitrogen protection, sodium dodecyl sulfate, stearic acid, modified nano zinc oxide, multi-walled carbon nanotubes and magnesium oxide were mixed in a mass ratio of 6:5:1:1:3 and stirred at 900 rpm for 15 minutes to form a stable blend;

[0050] Step 4: curing and molding the blend through a condensation granulation process to obtain a low-zinc and high-efficiency composite activator for blended rubber;

[0051] The multi-walled carbon nanotubes are modified, and the specific modification steps are as follows:

[0052] Multi-walled carbon nanotubes were weighed and prepared into a 1% aqueous solution, which was then dispersed by ultrasonic treatment for 5 minutes. Sericin and the aqueous solution were mixed in a mass ratio of 10:3 and magnetically stirred at a constant temperature of 45°C for 30 minutes to obtain a mixed system. The mixed system was then ultrasonically treated again for 5 minutes to obtain modified multi-walled carbon nanotubes.

[0053] Example 2: A low-zinc, high-efficiency composite active agent for blended rubber and a preparation method thereof, comprising the following steps:

[0054] Step 1: 1g zinc acetate, 2g zinc nitrate, 5g zinc sulfate and 30g urea were mixed, 100mL distilled water was added, and the mixture was stirred until completely dissolved, and then heated to 95°C and kept warm for 2.5h. After the reaction was completed, the mixture was cooled to 25°C and filtered. The obtained solid was washed with ammonia water and anhydrous ethanol in sequence to remove residual impurities. After washing, the solid was filtered and dried in a vacuum drying oven for 28h. The dried product was ground to make it fine and uniform, and calcined at 470°C for 2.3h to obtain nano zinc oxide.

[0055] Step 2: 25 g of nano-zinc oxide and 100 mL of distilled water were mixed and stirred at an ultrasonic frequency of 55 Hz for 33 minutes to obtain a nano-zinc oxide suspension; 1.25 g of polypropylene glycol and 100 mL of distilled water were mixed and dissolved, and then added to the nano-zinc oxide suspension and stirred at 23° C. for 22 hours; the particles were collected by centrifugation, washed with distilled water, and dried at 110° C. for 6.5 hours to obtain modified nano-zinc oxide;

[0056] Step 3: Under nitrogen protection, sodium dodecyl sulfate, stearic acid, modified nano zinc oxide, multi-walled carbon nanotubes and magnesium oxide were mixed in a mass ratio of 6:5:1:1:3 and stirred at a speed of 1100 rpm for 17 minutes to form a stable blend;

[0057] Step 4: curing and molding the blend through a condensation granulation process to obtain a low-zinc and high-efficiency composite activator for blended rubber;

[0058] The multi-walled carbon nanotubes are modified, and the specific modification steps are as follows:

[0059] Multi-walled carbon nanotubes were weighed and prepared into a 1% aqueous solution, which was then dispersed by ultrasonic treatment for 5 minutes. Sericin and the aqueous solution were mixed in a mass ratio of 10:3 and magnetically stirred at a constant temperature of 47°C for 33 minutes to obtain a mixed system. The mixed system was then ultrasonically treated again for 5 minutes to obtain modified multi-walled carbon nanotubes.

[0060] Example 3: A low-zinc, high-efficiency composite active agent for blended rubber and a preparation method thereof, comprising the following steps:

[0061] Step 1: 1g zinc acetate, 2g zinc nitrate, 5g zinc sulfate and 30g urea were mixed, 100mL distilled water was added, and the mixture was stirred until completely dissolved, and then heated to 100°C and kept warm for 3h. After the reaction was completed, the mixture was cooled to 30°C and filtered. The obtained solid was washed with ammonia water and anhydrous ethanol in sequence to remove residual impurities. After washing, it was filtered and dried in a vacuum drying oven for 30h. The dried product was ground to make it fine and uniform, and calcined at 500°C for 2.5h to obtain nano zinc oxide.

[0062] Step 2: 25 g of nano-zinc oxide and 100 mL of distilled water were mixed and stirred at an ultrasonic frequency of 60 Hz for 35 minutes to obtain a nano-zinc oxide suspension; 1.25 g of polypropylene glycol was mixed and dissolved in 100 mL of distilled water and then added to the nano-zinc oxide suspension, and stirred at 25° C. for 24 hours; the particles were collected by centrifugation, washed with distilled water, and dried at 120° C. for 7 hours to obtain modified nano-zinc oxide;

[0063] Step 3: Under nitrogen protection, sodium dodecyl sulfate, stearic acid, modified nano zinc oxide, multi-walled carbon nanotubes and magnesium oxide were mixed in a mass ratio of 6:5:1:1:3 and stirred at a speed of 1300 rpm for 30 minutes to form a stable blend;

[0064] Step 4: curing and molding the blend through a condensation granulation process to obtain a low-zinc and high-efficiency composite activator for blended rubber;

[0065] The multi-walled carbon nanotubes are modified, and the specific modification steps are as follows:

[0066] Multi-walled carbon nanotubes were weighed and prepared into a 1% aqueous solution, which was then dispersed by ultrasonic treatment for 5 minutes. Sericin and the aqueous solution were mixed in a mass ratio of 10:3 and magnetically stirred at a constant temperature of 50°C for 35 minutes to obtain a mixed system. The mixed system was then ultrasonically treated again for 5 minutes to obtain modified multi-walled carbon nanotubes.

[0067] Comparative Example 1: A low-zinc, high-efficiency composite active agent for blended rubber and a preparation method thereof, comprising the following steps:

[0068] The nano zinc oxide in Example 3 was replaced with unmodified nano zinc oxide;

[0069] Step 1: 1g zinc acetate, 2g zinc nitrate, 5g zinc sulfate and 30g urea were mixed, 100mL distilled water was added, and the mixture was stirred until completely dissolved, and then heated to 100°C and kept warm for 3h. After the reaction was completed, the mixture was cooled to 30°C and filtered. The obtained solid was washed with ammonia water and anhydrous ethanol in sequence to remove residual impurities. After washing, it was filtered and dried in a vacuum drying oven for 30h. The dried product was ground to make it fine and uniform, and calcined at 500°C for 2.5h to obtain nano zinc oxide.

[0070] Step 2: Under nitrogen protection, sodium dodecyl sulfate, stearic acid, nano zinc oxide, multi-walled carbon nanotubes and magnesium oxide were mixed in a mass ratio of 6:5:1:1:3 and stirred at a speed of 1300 rpm for 30 minutes to form a stable blend;

[0071] Step 3: curing and molding the blend through a condensation granulation process to obtain a low-zinc and high-efficiency composite activator for blended rubber;

[0072] The multi-walled carbon nanotubes are modified, and the specific modification steps are as follows:

[0073] Multi-walled carbon nanotubes were weighed and prepared into a 1% aqueous solution, which was then dispersed by ultrasonic treatment for 5 minutes. Sericin and the aqueous solution were mixed in a mass ratio of 10:3 and magnetically stirred at a constant temperature of 50°C for 35 minutes to obtain a mixed system. The mixed system was then ultrasonically treated again for 5 minutes to obtain modified multi-walled carbon nanotubes.

[0074] Comparative Example 2: A low-zinc, high-efficiency composite active agent for blended rubber and a preparation method thereof, comprising the following steps:

[0075] The multi-walled carbon nanotubes in Example 3 were replaced with unmodified multi-walled carbon nanotubes;

[0076] Step 1: 1g zinc acetate, 2g zinc nitrate, 5g zinc sulfate and 30g urea were mixed, 100mL distilled water was added, and the mixture was stirred until completely dissolved, and then heated to 100°C and kept warm for 3h. After the reaction was completed, the mixture was cooled to 30°C and filtered. The obtained solid was washed with ammonia water and anhydrous ethanol in sequence to remove residual impurities. After washing, it was filtered and dried in a vacuum drying oven for 30h. The dried product was ground to make it fine and uniform, and calcined at 500°C for 2.5h to obtain nano zinc oxide.

[0077] Step 2: 25 g of nano-zinc oxide and 100 mL of distilled water were mixed and stirred at an ultrasonic frequency of 60 Hz for 35 minutes to obtain a nano-zinc oxide suspension; 1.25 g of polypropylene glycol was mixed and dissolved in 100 mL of distilled water and then added to the nano-zinc oxide suspension, and stirred at 25° C. for 24 hours; the particles were collected by centrifugation, washed with distilled water, and dried at 120° C. for 7 hours to obtain modified nano-zinc oxide;

[0078] Step 3: Under nitrogen protection, sodium dodecyl sulfate, stearic acid, modified nano zinc oxide, multi-walled carbon nanotubes and magnesium oxide were mixed in a mass ratio of 6:5:1:1:3 and stirred at a speed of 1300 rpm for 30 minutes to form a stable blend;

[0079] Step 4: The blend is solidified and formed through a condensation granulation process to obtain a low-zinc and high-efficiency composite activator for blended rubber.

[0080] Comparative Example 3: A low-zinc, high-efficiency composite active agent for blended rubber and a preparation method thereof, comprising the following steps:

[0081] The multi-walled carbon nanotube component in Example 3 was removed;

[0082] Step 1: 1g zinc acetate, 2g zinc nitrate, 5g zinc sulfate and 30g urea were mixed, 100mL distilled water was added, and the mixture was stirred until completely dissolved, and then heated to 100°C and kept warm for 3h. After the reaction was completed, the mixture was cooled to 30°C and filtered. The obtained solid was washed with ammonia water and anhydrous ethanol in sequence to remove residual impurities. After washing, it was filtered and dried in a vacuum drying oven for 30h. The dried product was ground to make it fine and uniform, and calcined at 500°C for 2.5h to obtain nano zinc oxide.

[0083] Step 2: 25 g of nano-zinc oxide and 100 mL of distilled water were mixed and stirred at an ultrasonic frequency of 60 Hz for 35 minutes to obtain a nano-zinc oxide suspension; 1.25 g of polypropylene glycol was mixed and dissolved in 100 mL of distilled water and then added to the nano-zinc oxide suspension, and stirred at 25° C. for 24 hours; the particles were collected by centrifugation, washed with distilled water, and dried at 120° C. for 7 hours to obtain modified nano-zinc oxide;

[0084] Step 3: Under nitrogen protection, sodium lauryl sulfate, stearic acid, modified nano zinc oxide and magnesium oxide were mixed in a mass ratio of 6:5:1:3 and stirred at a speed of 1300 rpm for 30 minutes to form a stable blend;

[0085] Step 4: The blend is solidified and formed through a condensation granulation process to obtain a low-zinc and high-efficiency composite active agent for blended rubber.

[0086] Experiment: The low-zinc and high-efficiency composite active agent for blended rubber obtained in Examples 1-3 and Comparative Examples 1-3 was applied to blended rubber products. The blended rubber formula consisted of 60 parts of natural rubber, 20 parts of butadiene rubber, 20 parts of styrene-butadiene rubber, 30 parts of white carbon black, 5 parts of low-zinc and high-efficiency composite active agent for blended rubber, 1.5 parts of accelerator DM, 2 parts of sulfur, and 2 parts of antioxidant RD. The properties of the blended rubber were tested and the test results were recorded:

[0087] Tensile strength and elongation at break test: Based on GB / T 528-2009 as the reference standard, the tensile properties of the specimens were tested using an electronic tensile testing machine at a tensile rate of 500 mm / min. The specimens were dumbbell-shaped, 25 mm long, and 2 mm thick.

[0088] Tear strength test: Based on GB / T 529-2008 as the reference standard, the tear performance test was conducted on the specimens using a tensile testing machine at a tensile rate of 100 mm / min. The specimens were trouser-shaped, with the cut located at the center of the specimen width, a depth of 40 mm, a thickness of 2 mm, a width of 15 mm, and a length of 100 mm.

[0089] The results are shown in Table 1.

[0090] Table 1

[0091] Test items Tensile strength / MPa Elongation at break / % Tear strength / (KN / m) Example 1 25.0 485.0 85.0 Example 2 25.7 490.2 86.7 Example 3 26.3 494.7 87.5 Comparative Example 1 23.0 435.3 77.0 Comparative Example 2 24.0 455.1 80.5 Comparative Example 3 22.0 425.4 75.9

[0092] According to the data in Table 1, the following conclusions can be clearly drawn:

[0093] Compared with the comparative example, the low-zinc and high-efficiency composite active agent for the blended rubber obtained in Examples 1-3 is used in the blended rubber, so that the blended rubber has higher tensile strength, elongation at break and tear strength. This fully demonstrates that the low-zinc and high-efficiency composite active agent for the blended rubber prepared by the present invention has good dispersibility, enhances the mechanical properties of the blended rubber, and is suitable for the blended rubber system.

[0094] Compared with Example 3, the nano zinc oxide used in Comparative Example 1 was unmodified. The tensile strength, elongation at break and tear strength of the blended rubber to which the low-zinc and high-efficiency composite activator for blended rubber obtained in Comparative Example 1 was added were significantly reduced, indicating that the unmodified nano zinc oxide was easy to agglomerate and had poor dispersibility, thereby affecting the mechanical properties of the blended rubber.

[0095] Compared with Example 3, the multi-walled carbon nanotubes used in Comparative Example 2 were not modified, and no multi-walled carbon nanotubes were added to Comparative Example 3. The tensile strength, elongation at break, and tear strength of the two blended rubber samples to which the low-zinc, high-efficiency composite activator for blended rubber obtained in Comparative Examples 2 and 3 were added were all reduced, indicating that the addition of modified carbon nanotubes can improve the dispersibility of the low-zinc, high-efficiency composite activator for blended rubber in the blended rubber and enhance the bonding interface strength, thereby improving the mechanical properties of the blended rubber.

[0096] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include," "comprise," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0097] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing a low-zinc, high-efficiency composite active agent for blended rubber, characterized in that: The following steps are involved: Step 1: Mix zinc acetate, zinc nitrate, zinc sulfate and urea, add distilled water, stir until dissolved and then heat to react; After the reaction is completed, the mixture is cooled and filtered, and the resulting solid is washed with ammonia water and anhydrous ethanol in sequence, filtered and dried; the dried product is ground and calcined to obtain nano zinc oxide; Step 2: Mixing nano zinc oxide and distilled water, and ultrasonically stirring to obtain a nano zinc oxide suspension; mixing and dissolving polypropylene glycol and distilled water, and then adding the mixture to the nano zinc oxide suspension and stirring; collecting particles by centrifugation, washing with distilled water, and drying to obtain modified nano zinc oxide; Step 3: Under the protection of inert gas, the dispersant, stearic acid, modified nano zinc oxide, multi-walled carbon nanotubes and magnesium oxide are mixed and stirred to form a blend; Step 4: The blend is solidified and formed through a condensation granulation process to obtain a low-zinc and high-efficiency composite activator for blended rubber.

2. The method for preparing a low-zinc, high-efficiency composite active agent for blended rubber according to claim 1, characterized in that: The zinc acetate, zinc nitrate, zinc sulfate and urea are mixed in a mass ratio of 1:2:5:

30.

3. The method for preparing a low-zinc, high-efficiency composite active agent for blended rubber according to claim 1, characterized in that: In step 2, the nano zinc oxide and distilled water are mixed at a mass ratio of 1:4, and the polypropylene glycol and distilled water are mixed at a mass ratio of 1:

80.

4. The method for preparing a low-zinc, high-efficiency composite active agent for blended rubber according to claim 1, characterized in that: The inert gas is one of nitrogen, helium and carbon dioxide.

5. The method for preparing a low-zinc, high-efficiency composite active agent for blended rubber according to claim 1, characterized in that: The dispersant is sodium dodecylbenzenesulfonate.

6. The method for preparing a low-zinc, high-efficiency composite active agent for blended rubber according to claim 1, characterized in that: The dispersant, stearic acid, modified nano zinc oxide, multi-walled carbon nanotubes and magnesium oxide are mixed in a mass ratio of 6:5:1:1:

3.

7. The method for preparing a low-zinc, high-efficiency composite activator for blended rubber according to claim 1, characterized in that: The multi-walled carbon nanotubes are modified, and the specific modification steps are as follows: Multi-walled carbon nanotubes were weighed and prepared into a 1% by mass aqueous solution, which was then dispersed by ultrasonic treatment. Sericin was immersed in the aqueous solution and magnetically stirred at a constant temperature to obtain a mixed system. The mixed system was further ultrasonically treated to obtain modified multi-walled carbon nanotubes.

8. The method for preparing a low-zinc, high-efficiency composite activator for blended rubber according to claim 7, characterized in that: The multi-walled carbon nanotubes have a diameter of 8 to 10 nm and a length of 50 to 100 μm. The mass ratio of sericin to the multi-walled carbon nanotube aqueous solution is 10:

3. The magnetic stirring conditions are 45 to 50° C. and stirring for 30 to 35 minutes.

9. The method for preparing a low-zinc high-efficiency composite activator for blended rubber according to claim 1, characterized in that: The heating reaction conditions in step 1 are a heating temperature of 90-100° C., a reaction of 2-3 hours, and a calcination condition of 450-500° C. for 2-2.5 hours; the ultrasonic stirring conditions in step 2 are a frequency of 50-60 Hz, a time of 30-35 minutes, and a stirring condition of stirring at 20-25° C. for 20-24 hours after adding the mixture of polypropylene glycol and distilled water; and the stirring conditions in step 3 are stirring at a speed of 900-1300 rpm for 15-30 minutes.

10. A low-zinc, high-efficiency composite activator for blended rubber obtained according to the preparation method according to any one of claims 1 to 9.