A sepiolite-loaded zinc oxide material and its highly active natural rubber composite material

Abstract

The present invention discloses a sepiolite-loaded zinc oxide material and a high-activity natural rubber composite material thereof, relating to the technical field of natural rubber composite materials. The method covers the entire process from preparing a sepiolite suspension, adding a divalent zinc salt and an alkali, filtering and drying, to treating in a high-temperature atmosphere furnace. In addition, the scheme also includes a method for preparing a high-activity natural rubber / zinc oxide masterbatch using this material, emphasizing the precise control of operating parameters and the mixing process of natural latex and loaded zinc oxide. The present invention uses the structure of sepiolite to uniformly load zinc oxide onto its fiber surface, constructs a stable three-dimensional network in an aqueous phase system, and significantly improves the dispersibility and stability of zinc oxide. Traditional grinding and surfactants are abandoned, the production process is simplified, energy consumption is reduced, and economic efficiency and environmental protection are improved. The zinc oxide in the obtained masterbatch is dispersed at the nanoscale, effectively promoting vulcanization and cross-linking, and improving the performance of rubber products.

Description

Technical Field

[0001] The present invention relates to the technical field of natural rubber composite materials, in particular to a sepiolite-loaded zinc oxide material and a high-activity natural rubber composite material thereof. Background Art

[0002] Vulcanization of rubber composites is a necessary stage to achieve their applicable physical and mechanical properties. Improving vulcanization efficiency and shortening vulcanization time can also save resources and energy. The rubber vulcanization system includes activators, accelerators and vulcanizing agents. Among them, zinc oxide is considered to be the best activator for the vulcanization and cross-linking of rubber materials. During the vulcanization process, zinc oxide and stearic acid first form a Zn 2+ The intermediate complex then reacts with the accelerator to form a particularly active zinc chelate, which then interacts with sulfur to form a zinc polysulfide complex, which further combines with the rubber precursor chain to form a cross-linked structure. 2+ Therefore, the amount, size, specific surface area of ​​zinc oxide particles and their dispersion in the rubber matrix have a great influence on the vulcanization characteristics of rubber composites.

[0003] Zinc oxide is an indispensable additive in rubber formulation systems and, besides reinforcing fillers, the most in-demand rubber compounding additive in the rubber industry. However, studies have shown that zinc oxide can be reproductively toxic to aquatic organisms. It is released into the environment during the production, decomposition, and recycling of rubber products, as well as through leaching in landfills and tire wear, which undoubtedly leads to a series of ecological and environmental problems. Therefore, researchers have explored various methods to reduce the use of zinc oxide. These methods mainly include replacing the traditional indirect zinc oxide process with nano-zinc oxide of different structural morphologies, active zinc oxide with high specific surface area and low particle size, and core-shell nano-zinc oxide. While theoretically effective, these methods still suffer from poor zinc oxide dispersion under the current traditional dry mixing process, and cannot prevent the loss of zinc oxide particles during processing.

[0004] It is well known that rubber wet mixing is an energy-saving and environmentally friendly process for improving the dispersion of filler additives in the rubber matrix. However, for additives with higher density, such as zinc oxide, it is often necessary to add a large amount of surfactant and a long grinding process to prepare an aqueous zinc oxide slurry suitable for rubber wet mixing. This method can effectively crosslink latex products, but it is not suitable for rubber products with dynamic applications such as tires and drive belts. Therefore, it would be very meaningful to explore the wet mixing of zinc oxide and rubber latex without the use of organic surfactants.

[0005] Sepiolite is a natural magnesium-rich hydrated silicate clay mineral with a unique one-dimensional fibrous crystal morphology. Its lattice is generally believed to be composed of Si-O tetrahedral sheets and Mg-O octahedral sheets, with a 2:1 ribbon structure parallel to the C axis. Discontinuous octahedral sheets are connected to inverted tetrahedral sheets through alternating bonds formed by oxygen atoms. This alternating connection gives sepiolite a large number of channels and tunnels and a rich surface silanol (Si-OH) group structure, which gives it excellent adsorption, enhancement, and aqueous suspension stability. It can also stabilize inorganic fillers such as carbon nanotubes and graphene without the addition of surfactants.

[0006] Under the traditional dry mixing process, when nano zinc oxide, activated zinc oxide and core-shell structure zinc oxide replace conventional indirect zinc oxide, the problem of poor zinc oxide dispersibility still exists, and the damage caused by the loss of zinc oxide particles during the processing cannot be avoided. Under the existing technology, the mixing of zinc oxide and natural rubber latex requires a large amount of surfactants and a long grinding process to prepare a zinc oxide aqueous suspension. The process has high energy consumption and poor suspension stability. At the same time, this method is not suitable for rubber products with dynamic applications such as tires and transmission belts.

[0007] This invention uses sepiolite as a carrier to load zinc oxide onto the surface of the stone. Leveraging the unique structural properties of sepiolite, a stable aqueous sepiolite suspension containing zinc oxide is prepared. This suspension can then be directly wet-mixed with natural rubber latex to produce a highly active natural rubber / zinc oxide masterbatch. This preparation eliminates the need for surfactants and lengthy grinding processes, and the resulting masterbatch exhibits uniform nanoscale dispersion of zinc oxide, paving the way for a wider range of applications.

[0008] This invention utilizes the unique structural properties of sepiolite to uniformly load zinc oxide onto the surface of sepiolite fibers, producing a sepiolite-loaded zinc oxide material. In an aqueous system, after the fibers are unbundled, they physically overlap with each other, aided by weak chemical reactions, to form a stable three-dimensional network. The sepiolite's pore structure also binds some free water, forming a stable suspension. This material is then wet-mixed with natural rubber latex to produce a highly dispersed and active natural rubber / zinc oxide masterbatch. Summary of the Invention

[0009] In order to achieve the above-mentioned purpose of the invention, in view of the above-mentioned technical problems,

[0010] The present invention provides a sepiolite-loaded zinc oxide material, which is prepared by the following steps:

[0011] A1: adding sepiolite powder to water and preparing a sepiolite suspension with a certain solid content under high-speed stirring or ultrasonic dispersion;

[0012] A2 adds a divalent zinc salt to the sepiolite suspension obtained in A1 under heating and stirring, the amount added being 10% to 100% of the mass of the sepiolite. After complete dissolution, a fixed amount of base is added in batches, the amount added being twice the molar amount of the divalent zinc salt used. After the reaction is complete, a sepiolite-loaded zinc hydroxide suspension is obtained;

[0013] A3 filters and washes the sepiolite-loaded zinc hydroxide suspension in A2, then dries and crushes it to obtain sepiolite-loaded zinc hydroxide powder;

[0014] A4: placing the sepiolite-loaded zinc hydroxide powder obtained in A3 into a high-temperature air atmosphere furnace for reaction to obtain a sepiolite-loaded zinc oxide material.

[0015] Preferably, the speed of high-speed stirring in step A1 is 1000 rpm-20000 rpm; the energy required for ultrasonic dispersion per gram of sepiolite suspension is 0.1-5 J / g; and the sepiolite solid content of the sepiolite suspension is 1%-5%.

[0016] Preferably, the heating temperature in step A2 is 25° C.-100° C.; the added divalent zinc salt is one of zinc chloride, zinc acetate and zinc sulfate; and the quantitative base is one of sodium hydroxide, potassium hydroxide and ammonia water.

[0017] Preferably, the particle size of the sepiolite-loaded zinc hydroxide powder in step A3 is 1 μm-100 μm.

[0018] Preferably, the heating temperature of the high-temperature atmosphere furnace in step A4 is 100°C-550°C.

[0019] The present invention also provides a high-activity natural rubber / zinc oxide masterbatch, which is prepared by the following steps:

[0020] B1: adding sepiolite-loaded zinc oxide material into water, and obtaining a sepiolite-loaded zinc oxide aqueous suspension having a certain solid content under high-speed stirring or ultrasonic dispersion;

[0021] B2: adding natural rubber latex to the aqueous suspension obtained in B1, stirring at 10-500 rpm for 10-60 min to obtain a mixed slurry of natural rubber latex and zinc oxide-loaded sepiolite suspension, wherein the total amount of zinc oxide-loaded sepiolite added is 10 to 100 parts based on 100 parts of dry rubber in the natural rubber latex;

[0022] B3: slowly adding the diluted flocculant to the mixed slurry obtained in B2, with the added amount being 0-1.0% of the dry weight of the natural rubber latex; after stirring and flocculating, squeezing, dehydrating and washing, and then crushing and drying to obtain a high-activity natural rubber / zinc oxide masterbatch.

[0023] Preferably, the sepiolite-loaded zinc oxide material is a sepiolite-loaded zinc oxide material prepared by the above-mentioned preparation method.

[0024] Preferably, the high-speed stirring speed in step B1 is 1000 rpm-20000 rpm; the energy required for ultrasonic dispersion of each gram of zinc oxide-loaded sepiolite suspension is 0.1-5 J / g; and the solid content of the zinc oxide-loaded sepiolite aqueous suspension is between 1% and 10%.

[0025] Preferably, in step B2, the natural latex is a mixture of one or more of field natural latex, concentrated natural latex, and epoxidized natural latex with a solid content of 20% to 50%.

[0026] Preferably, in step B3, the added flocculant is one or more of formic acid, calcium chloride, methanol, and protease.

[0027] The beneficial effects brought about by the technical solution provided by the present invention are:

[0028] The present invention utilizes the unique structural properties of sepiolite to uniformly load zinc oxide onto the surface of sepiolite fibers. In an aqueous system, after the fibers are unbundled, they are physically bonded to each other through weak chemical interactions, forming a stable three-dimensional network structure, effectively improving the dispersibility of the zinc oxide. The sepiolite's pore structure partially binds free water, creating a highly stable suspension system that prevents zinc oxide loss during processing and addresses the poor dispersibility of zinc oxide in traditional dry mixing processes.

[0029] The preparation process of this invention eliminates the traditional use of surfactants and lengthy grinding processes, simplifying the production process and significantly reducing energy consumption. By leveraging the physical and chemical structural properties of sepiolite, zinc oxide is directly and stably loaded and dispersed, effectively reducing the need for complex chemical treatments and mechanical energy, thereby improving the economic efficiency and environmental friendliness of the entire preparation process.

[0030] The resulting natural rubber / zinc oxide masterbatch features uniformly dispersed zinc oxide at the nanometer scale. This high dispersion significantly improves the performance of rubber products in dynamic applications, such as tires and drive belts. Nano-dispersed zinc oxide more effectively promotes vulcanization and crosslinking, reducing zinc oxide usage while enhancing the durability and elasticity of rubber products. This effect directly addresses the technical needs of improving product performance and reducing material costs.

[0031] Compared to aqueous zinc oxide suspensions that require surfactant treatment, the sepiolite-loaded zinc oxide material of the present invention is not only applicable to the preparation of traditional rubber products, but can also be widely used in various high-performance composite materials requiring high dispersibility and stability. The versatility and expanded scope of application of this material are important supplements and improvements to existing technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The X-ray diffraction patterns of the sepiolite-loaded zinc oxide material, the original sepiolite, and zinc oxide in the present invention;

[0033] Figure 2 is a scanning electron microscope (SEM) image of the sepiolite-loaded zinc oxide material of the present invention;

[0034] Figure 3 This is a transmission electron microscope (TEM) image of the sepiolite-loaded zinc oxide material of the present invention;

[0035] Figure 4 This is a scanning electron microscope (SEM) image of the brittle cross section of a vulcanized rubber of a high-activity natural rubber composite material prepared by a wet process using sepiolite-loaded zinc oxide material, characterizing the dispersion state of zinc oxide in the rubber matrix;

[0036] Figure 5 This is a transmission electron microscope (TEM) image of the brittle fracture surface of a vulcanized rubber of a high-activity natural rubber composite material prepared by a wet process using sepiolite-loaded zinc oxide material, characterizing the dispersion state of zinc oxide in the rubber matrix;

[0037] Figure 6 This is a scanning electron microscope (SEM) image of the brittle fracture surface of a natural rubber composite material vulcanized by mixing zinc oxide with the existing dry method;

[0038] Figure 7 This is a transmission electron microscope (TEM) image of the brittle fracture surface of a vulcanized natural rubber composite material obtained by dry mixing zinc oxide. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the embodiments. Of course, the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0040] Example 1

[0041] A method for preparing nano-level super-anti-slip tiles, the implementation steps are as follows:

[0042] Example 1:

[0043] Add 10g of sepiolite to 490g of water and stir at 10,000rpm for 20 minutes to obtain a sepiolite suspension with a 2% solids content. Then, add 0.840g of ZnCl2 and stir at 60°C. Simultaneously, dissolve 0.494g of NaOH in 100ml of deionized water. Once the ZnCl2 is completely dissolved, add the prepared NaOH solution to the ZnCl2-containing sepiolite suspension in five portions, 10 minutes apart. Continue heating and stirring for 2 hours after each addition. Then, filter and rinse the mixture three times to remove any salts generated. After rinsing, dry the mixture in a 60°C oven for 24 hours and grind it into a powder. Finally, the powder was placed in a vacuum furnace and heated at 300°C for 2 hours to obtain a sepiolite loaded with 0.5g of zinc oxide; the sepiolite loaded with zinc oxide was added to water and dispersed under 3J / g ultrasound for 15 minutes to prepare a suspension with a solid content of 4%, and then 333.4g of concentrated natural rubber latex diluted to 30% solid content was added and stirred at 500rpm for 30 minutes. Subsequently, it was flocculated with a 2% concentration of calcium chloride solution, soaked and washed several times, and then vacuum dried at 60°C for 4 hours. 8h, a high-activity natural rubber / zinc oxide masterbatch containing 0.5g zinc oxide, 10g sepiolite and 100g natural rubber was obtained; the masterbatch was mixed with 2phr stearic acid, 1.35phr accelerator NS and 1.5phr sulfur in an open mill to obtain a rubber mix. After standing for 12h, the vulcanization curve was measured at 150℃, and the results are shown in Table 1; the rubber mix was vulcanized under the vulcanization conditions of 150℃, 10MPa, t90+3min, and the physical and mechanical properties and crosslinking density were tested, and the results are shown in Table 2.

[0044] Example 2:

[0045] Add 10g of sepiolite to 490g of water and stir at 10,000rpm for 20 minutes to obtain a sepiolite suspension with a 2% solids content. Then, add 1.679g of ZnCl2 and stir at 60°C. Simultaneously, dissolve 0.988g of NaOH in 100ml of deionized water. Once the ZnCl2 is completely dissolved, add the prepared NaOH solution to the ZnCl2-containing sepiolite suspension in five portions, 10 minutes apart. Continue heating and stirring for 2 hours after each addition. Then, filter and rinse the mixture three times to remove any salts generated. After rinsing, dry the mixture in a 60°C oven for 24 hours and grind it into a powder. Finally, the powder was placed in a vacuum furnace and heated at 300°C for 2 hours to obtain a sepiolite loaded with 1.0 g of zinc oxide; the zinc oxide-loaded sepiolite was added to water and dispersed under 3 J / g ultrasound for 15 minutes to prepare a suspension with a solid content of 4%, followed by the addition of 333.4 g of concentrated natural rubber latex diluted to a solid content of 30%, and stirred at 500 rpm for 30 minutes. The mixture was then flocculated and washed several times with a 2% concentration of calcium chloride solution, and then vacuum dried at 60°C for 48 hours to obtain a high-activity natural rubber / zinc oxide masterbatch containing 1.0 g of zinc oxide, 10 g of sepiolite, and 100 g of natural rubber; the mixing processing and testing steps and results of the obtained masterbatch were the same as those in Example 1.

[0046] Example 3:

[0047] Add 10g of sepiolite to 490g of water and stir at 10,000rpm for 20 minutes to obtain a sepiolite suspension with a 2% solids content. Then, add 2.591g of ZnCl2 and stir at 60°C. Simultaneously, dissolve 1.481g of NaOH in 100ml of deionized water. Once the ZnCl2 is completely dissolved, add the prepared NaOH solution to the ZnCl2-containing sepiolite suspension in five portions, 10 minutes apart. After the additions are complete, continue heating and stirring for 2 hours. The mixture is then filtered and washed three times to remove any salts generated. After washing, dry the mixture in a 60°C oven for 24 hours and grind it into a powder. Finally, the powder was placed in a vacuum furnace and heated at 300°C for 2 hours to obtain a sepiolite loaded with 1.5 g of zinc oxide; the zinc oxide-loaded sepiolite was added to water and dispersed under 3 J / g ultrasound for 15 minutes to prepare a suspension with a solid content of 4%, followed by the addition of 333.4 g of concentrated natural rubber latex diluted to a solid content of 30%, and stirred at 500 rpm for 30 minutes. The mixture was then flocculated and washed several times with a 2% calcium chloride solution, and then vacuum dried at 60°C for 48 hours to obtain a high-activity natural rubber / zinc oxide masterbatch containing 1.5 g of zinc oxide, 10 g of sepiolite, and 100 g of natural rubber; the mixing processing and testing steps and results of the obtained masterbatch were the same as those in Example 1.

[0048] Example 4:

[0049] Add 10g of sepiolite to 490g of water and stir at 10,000rpm for 20 minutes to obtain a sepiolite suspension with a 2% solids content. Then, add 3.358g of ZnCl2 and stir at 60°C. Simultaneously, dissolve 1.975g of NaOH in 100ml of deionized water. Once the ZnCl2 is completely dissolved, add the prepared NaOH solution to the ZnCl2-containing sepiolite suspension in five portions, 10 minutes apart. Continue heating and stirring for 2 hours after each addition. Then, filter and rinse the mixture three times to remove any salts generated. After rinsing, dry the mixture in a 60°C oven for 24 hours and grind it into a powder. Finally, the powder was placed in a vacuum furnace and heated at 300°C for 2 hours to obtain a sepiolite loaded with 2.0 g of zinc oxide; the zinc oxide-loaded sepiolite was added to water and dispersed under 3 J / g ultrasound for 15 minutes to prepare a suspension with a solid content of 4%, followed by the addition of 333.4 g of concentrated natural rubber latex diluted to a solid content of 30%, and stirred at 500 rpm for 30 minutes. The mixture was then flocculated and washed several times with a 2% calcium chloride solution, and then vacuum dried at 60°C for 48 hours to obtain a high-activity natural rubber / zinc oxide masterbatch containing 2.0 g of zinc oxide, 10 g of sepiolite, and 100 g of natural rubber; the mixing processing and testing steps and results of the obtained masterbatch were the same as those in Example 1.

[0050] Example 5:

[0051] Take 10g of sepiolite and add it to 490g of water, stir it at 10000rpm for 20min to obtain a sepiolite suspension with a solid content of 2%, then add 5.037g of ZnCl2 and stir at 60℃; at the same time, take 2.963g of NaOH and add it to 100ml of deionized water to dissolve; after ZnCl2 is completely dissolved, add the prepared NaOH solution to the sepiolite suspension containing ZnCl2 in 5 times, with an interval of 10min each time. After the addition is completed, continue heating and stirring for 2h. Then filter and wash it 3 times to remove the salt generated in the system. After washing, place it in an oven at 60℃ and dry it for 24h, and grind it into powder. Finally, place the powder in a vacuum atmosphere furnace and heat it at 300℃ for 2h to obtain sepiolite loaded with 3.0g zinc oxide, and its X-ray diffraction pattern (XRD) is as shown below. Figure 1 As shown, scanning electron microscopy SEM Figure 2 As shown, transmission electron microscopy TEM Figure 3As shown; the zinc oxide-loaded sepiolite was added to water, dispersed under ultrasonic action of 3 J / g for 15 minutes to prepare a suspension with a solid content of 4%, then 333.4 g of concentrated natural rubber latex diluted to 30% solid content was added and stirred at 500 rpm for 30 minutes, followed by flocculation with a 2% concentration of calcium chloride solution, soaking and washing several times, and vacuum drying at 60°C for 48 hours to obtain a high-activity natural rubber / zinc oxide masterbatch containing 3.0 g zinc oxide, 10 g sepiolite and 100 g natural rubber; the mixing processing and testing steps and results of the obtained masterbatch were the same as those in Example 1. In addition, the SEM and TEM images of the brittle fracture surface of the obtained masterbatch vulcanized rubber are as shown below. Figure 4 and Figure 5 shown.

[0052] Example 6:

[0053] Add 10g of sepiolite to 490g of water and stir at 10,000rpm for 20 minutes to obtain a sepiolite suspension with a 2% solids content. Then, add 8.395g of ZnCl2 and stir at 60°C. Simultaneously, dissolve 4.938g of NaOH in 100ml of deionized water. Once the ZnCl2 is completely dissolved, add the prepared NaOH solution to the ZnCl2-containing sepiolite suspension in five portions, 10 minutes apart. Continue heating and stirring for 2 hours after each addition. Then, filter and rinse the mixture three times to remove any salts generated. After rinsing, dry the mixture in a 60°C oven for 24 hours and grind it into a powder. Finally, the powder was placed in a vacuum furnace and heated at 300°C for 2 hours to obtain a sepiolite loaded with 5.0 g of zinc oxide; the zinc oxide-loaded sepiolite was added to water and dispersed under 3 J / g ultrasound for 15 minutes to prepare a suspension with a solid content of 4%, followed by the addition of 333.4 g of concentrated natural rubber latex diluted to a solid content of 30%, and stirred at 500 rpm for 30 minutes. The mixture was then flocculated and washed several times with a 2% calcium chloride solution, and then vacuum dried at 60°C for 48 hours to obtain a high-activity natural rubber / zinc oxide masterbatch containing 5.0 g of zinc oxide, 10 g of sepiolite, and 100 g of natural rubber; the mixing processing and testing steps and results of the obtained masterbatch were the same as those in Example 1.

[0054] Comparative Example 1:

[0055] Add 1.679g of ZnCl2 to 500ml of water and stir at 60°C until completely dissolved. Simultaneously, dissolve 0.988g of NaOH in 100ml of deionized water. Add the prepared NaOH solution to the ZnCl2 solution in five additions, 10 minutes apart. After the additions are complete, continue heating and stirring for 2 hours. Then, filter and rinse the solution three times to remove any salts generated. After rinsing, dry the solution in a 60°C oven for 24 hours and grind it into a powder. Finally, the powder was placed in a vacuum furnace and heated at 300°C for 2h to obtain 0.5g of zinc oxide particles (equivalent to 1phr of zinc oxide) for standby use; 10g of sepiolite was added to 240g of water and dispersed under 3J / g ultrasonic action for 15min to prepare a sepiolite suspension with a solid content of 4%, and then 333.4g of concentrated natural rubber latex diluted to 30% solid content was added and stirred at 500rpm for 30min, and then flocculated with 2% calcium chloride solution, soaked and washed several times. , vacuum dried at 60°C for 48h to obtain a masterbatch containing 10g of sepiolite and 100g of natural rubber; the above masterbatch and 1phr of the prepared zinc oxide were mixed with 2phr of stearic acid, 1.35phr of accelerator NS and 1.5phr of sulfur in an open mill to obtain a rubber mix. After standing for 12h, the vulcanization curve was measured at 150°C. The results are shown in Table 1; the rubber mix was vulcanized under the vulcanization conditions of 150°C, 10MPa, t90+3min, and the physical and mechanical properties and crosslinking density were tested. The results are shown in Table 2.

[0056] Comparative Example 2:

[0057] Take 3.358g of ZnCl2 and add it to 500ml of water, and stir at 60℃ until it is completely dissolved; at the same time, take 1.975g of NaOH and add it to 100ml of deionized water to dissolve; add the prepared NaOH solution to the ZnCl2 solution in 5 times, with an interval of 10 minutes each time. After the addition is completed, continue heating and stirring for 2h. Then filter and clean it 3 times to remove the salt generated in the system. After cleaning, place it in a 60℃ oven to dry for 24h and grind it into powder. Finally, place the powder in a vacuum atmosphere furnace and heat it at 300℃ for 2h to obtain 2.0g of zinc oxide particles (equivalent to 2phr zinc oxide) for standby use; the preparation method of natural rubber / sepiolite masterbatch and its mixing processing and testing steps with the prepared zinc oxide and other additives are the same as those in Comparative Example 1.

[0058] Comparative Example 3:

[0059] Take 5.037g of ZnCl2 and add it to 500ml of water, and stir at 60℃ until it is completely dissolved; at the same time, take 2.963g of NaOH and add it to 100ml of deionized water to dissolve; add the prepared NaOH solution to the ZnCl2 solution in 5 times, with an interval of 10 minutes each time. After the addition is completed, continue heating and stirring for 2h. Then filter and clean it 3 times to remove the salt generated in the system. After cleaning, place it in an oven at 60℃ and dry it for 24h, and grind it into powder. Finally, place the powder in a vacuum atmosphere furnace and heat it at 300℃ for 2h to obtain 2.0g of zinc oxide particles (equivalent to 2phr zinc oxide) for standby use; the preparation method of natural rubber / sepiolite masterbatch and its mixing processing and testing steps with the prepared zinc oxide and other additives are the same as those in comparative example 1. The SEM and TEM images of the brittle cross section of the obtained composite material vulcanized rubber are shown as follows: Figure 6 and Figure 7 shown.

[0060] Comparative Example 4:

[0061] Take 8.395g of ZnCl2 and add it to 500ml of water, and stir it at 60℃ until it is completely dissolved; at the same time, take 4.938g of NaOH and add it to 100ml of deionized water to dissolve; add the prepared NaOH solution to the ZnCl2 solution in 5 times, with an interval of 10 minutes each time. After the addition is completed, continue heating and stirring for 2h. Then filter and clean it 3 times to remove the salt generated in the system. After cleaning, place it in a 60℃ oven to dry for 24h and grind it into powder. Finally, place the powder in a vacuum atmosphere furnace and heat it at 300℃ for 2h to obtain 2.0g of zinc oxide particles (equivalent to 2phr zinc oxide) for standby use; the preparation method of natural rubber / sepiolite masterbatch and its mixing processing and testing steps with the prepared zinc oxide and other additives are the same as those in Comparative Example 1.

[0062] Table 1 Vulcanization characteristics of the rubber compounds obtained in the examples and comparative examples

[0063]

[0064] Table 2 Physical and mechanical properties and crosslinking density of the composite materials obtained in Examples and Comparative Examples

[0065]

[0066] It can be seen from the above performance data that the wet mixing application of sepiolite-loaded zinc oxide material enables zinc oxide to be dispersed at the nanometer level in the rubber matrix; at the same time, when the zinc oxide dosage is the same, the vulcanization efficiency, crosslinking density, tensile stress, tensile strength, tear strength and other properties of the natural rubber composite material obtained by the wet mixing of sepiolite-loaded zinc oxide are higher than those of the natural rubber composite material obtained by the traditional dry mixing; in addition, the application effect when the loaded zinc oxide dosage is 2phr can reach the application effect of traditional zinc oxide 3-5phr, indicating that it can effectively reduce the usage of zinc oxide.

[0067] Depend on Figure 1 According to the JCPDS #36-1451 zinc oxide standard card, characteristic diffraction peaks of ZnO are observed at 2θ = 31.7°, 34.4°, 36.2°, 47.5°, 56.6°, 62.8°, and 67.9°. The main characteristic peaks of sepiolite are observed at 2θ = 7.3°, as shown in the Sep spectrum in the figure. For the sepiolite-supported zinc oxide material, a strong characteristic peak at 2θ = 7.3° is still present, indicating that the loading of zinc oxide has not changed the original interplanar spacing of the sepiolite or disrupted its original crystal structure. Furthermore, the characteristic peaks at 2θ = 31.7°, 34.4°, 36.2°, 47.5°, 56.6°, 62.8°, and 67.9° are still present, with no additional diffraction peaks appearing. This indicates that the zinc oxide supported on the sepiolite has good crystallinity, demonstrating successful zinc oxide loading.

[0068] Figure 2 It can be clearly observed that some nano-scale particles are evenly distributed among the sepiolite fiber bundles, making the sepiolite fiber bundle structure look looser. From the magnified SEM image, it can be seen that these particles are deposited on the fiber surface individually or in clusters.

[0069] from Figure 3 It can be seen from the TEM image that a large number of dense irregular nanoparticles are produced on the surface of the cylindrical sepiolite fiber with a pore structure, and are tightly attached to the surface of the rod-shaped fiber. The size of these particles is about 20 to 30 nm, and when they are clustered, the size ranges from tens to hundreds of nanometers.

[0070] Depend on Figure 4 It can be seen that in the natural rubber composite material obtained by direct wet mixing, all filler particles are relatively evenly dispersed in the rubber matrix, and there are no obvious aggregated particles, indicating that sepiolite and loaded zinc oxide particles are well dispersed in the rubber matrix.

[0071] Depend on Figure 5 It can be seen that the sepiolite fibers in the composite material are dispersed relatively evenly, and the fiber length is all below 1 μm. At the same time, the zinc oxide particles are also evenly dispersed in the size of tens of nanometers, without any large zinc oxide particles agglomerating.

[0072] Depend on Figure 6 It can be seen that there are obvious aggregated particles in the cross section of the vulcanized rubber. Analysis shows that since the sepiolite particles are mixed into the rubber matrix through a wet process and are dispersed relatively evenly, these aggregated particles should mainly be zinc oxide particles.

[0073] pass Figure 7 The TEM image shows that there are large aggregated zinc oxide particles in the cross section of the composite material. This indicates that the zinc oxide particles in the composite material obtained by dry mixing zinc oxide are relatively poorly dispersed.

[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A sepiolite-loaded zinc oxide material, characterized in that: The material is prepared by the following steps: A1: adding sepiolite powder to water and preparing a sepiolite suspension having a sepiolite solid content of 1% to 5% under high-speed stirring or ultrasonic dispersion. The high-speed stirring speed is 1000 rpm to 20000 rpm. The ultrasonic dispersion requires an energy of 0.1 to 5 J / g per gram of the sepiolite suspension. A2 adds a divalent zinc salt to the sepiolite suspension obtained in A1 under heating and stirring, the amount of the added divalent zinc salt being 10%-100% of the mass of the sepiolite. After complete dissolution, a predetermined amount of base is added in batches, the amount of the added base being twice the molar amount of the divalent zinc salt used. After the reaction is complete, a sepiolite-loaded zinc hydroxide suspension is obtained, wherein the added divalent zinc salt is one of zinc chloride, zinc acetate, and zinc sulfate; and the predetermined amount of base is one of sodium hydroxide, potassium hydroxide, and ammonia. A3: filtering and cleaning the sepiolite-loaded zinc hydroxide suspension in A2, drying and crushing the suspension to obtain sepiolite-loaded zinc hydroxide powder, wherein the particle size of the sepiolite-loaded zinc hydroxide powder is 1µm-100µm; A4 places the sepiolite-loaded zinc hydroxide powder obtained in A3 into a high-temperature air atmosphere furnace for reaction to obtain a sepiolite-loaded zinc oxide material. The heating temperature of the high-temperature atmosphere furnace is 100°C-550°C.

2. The sepiolite-loaded zinc oxide material according to claim 1, wherein The heating temperature in step A2 is 25°C-100°C.

3. A highly active natural rubber / zinc oxide masterbatch, characterized in that: The masterbatch is prepared by the following steps: B1: adding a sepiolite-loaded zinc oxide material to water and subjecting the material to high-speed stirring or ultrasonic dispersion to obtain a zinc oxide-loaded sepiolite aqueous suspension having a certain solid content; the high-speed stirring speed is 1000 rpm to 20,000 rpm; the energy required for ultrasonic dispersion per gram of the zinc oxide-loaded sepiolite suspension is 0.1 to 5 J / g; and the solid content of the zinc oxide-loaded sepiolite aqueous suspension is between 1% and 10%; B2: adding natural rubber latex to the aqueous suspension obtained in B1, stirring at 10-500 rpm for 10-60 min to obtain a mixed slurry of natural rubber latex and zinc oxide-loaded sepiolite suspension, wherein the total amount of zinc oxide-loaded sepiolite added is 10 to 100 parts based on 100 parts of dry rubber in the natural rubber latex; B3: slowly adding the diluted flocculant to the mixed slurry obtained in B2 in an amount of 0-1.0% of the dry weight of the natural rubber latex; stirring and flocculating, squeezing, dehydrating and rinsing, and then crushing and drying to obtain a high-activity natural rubber / zinc oxide masterbatch; The sepiolite-loaded zinc oxide material is a material prepared according to any one of claims 1-2.

4. The highly active natural rubber / zinc oxide masterbatch according to claim 3, characterized in that: In step B2, the natural rubber latex is a mixture of one or more of field natural rubber latex, concentrated natural rubber latex, and epoxidized natural rubber latex with a solid content of 20% to 50%.

5. The highly active natural rubber / zinc oxide masterbatch according to claim 3, characterized in that: In step B3, the added flocculant is one or more of formic acid, calcium chloride, methanol, and protease.

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