Lead-free anti-electromagnetic-ionizing radiation composite rubber material as well as preparation method and application thereof

Abstract

The invention provides a lead-free anti-electromagnetic-ionizing-radiation composite rubber material and a preparation method and application thereof, and belongs to the field of rubber composites.The preparation method includes the steps that a bismuth source, a samarium source and a cerium source are dissolved in a dilute nitric acid solution to obtain a precursor solution, the precursor solution is sequentially subjected to atomization pyrolysis, calcination and ultrasonic treatment to obtain anti-ionizing-radiation composite particles, and the anti-ionizing-radiation composite rubber material is obtained. The method comprises the following steps: coating the surfaces of anti-ionizing radiation composite particles with silver layers through a chemical reduction method to obtain an anti-electromagnetic-ionizing radiation filler with a core-shell structure, blending the filler with a surface treating agent, mixing with a rubber matrix, an active agent, a reinforcing agent, an anti-aging agent and a vulcanizing agent to obtain a lead-free anti-electromagnetic-ionizing radiation rubber compound, and vulcanizing and forming to obtain the lead-free anti-electromagnetic-ionizing radiation rubber compound. The lead-free anti-electromagnetic-ionizing radiation composite rubber material is obtained. The lead-free anti-radiation rubber material which is environmentally friendly, efficient and dual-functional is developed, the processing performance and the mechanical performance are considered while the protection requirement is met, and the lead-free anti-radiation rubber material has remarkable technical advantages and wide market application prospects.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rubber composites, in particular to a lead-free electromagnetic-ionizing radiation resistant composite rubber material and a preparation method and application thereof. BACKGROUND

[0002] With the progress of modern nuclear weapon technology and the development of nuclear industry, radiation hazards caused by nuclear leakage and other problems have become a serious social issue. Traditional nuclear radiation protection materials are mainly lead. Since lead has high biological toxicity, long-term contact or improper disposal can easily cause lead poisoning, posing a serious threat to personnel and the environment. Secondly, lead has a very high density, resulting in extremely heavy protective equipment (such as lead clothing) that can weigh up to 15-20 kilograms, severely limiting the activity flexibility and work duration of the wearer. Thirdly, lead has insufficient shielding effect on specific rays such as low-energy X-rays, forming a blind area of protection. Therefore, it is urgent to develop new lightweight, non-toxic and efficient radiation protection materials to replace traditional lead materials.

[0003] Currently, lightweight, non-biologically toxic, and ionizing / electromagnetic shielding synergistic nuclear radiation protection materials have become an international frontier research direction. Some researchers use heavy metal elements such as antimony, bismuth, tungsten, gadolinium, and tantalum as the main component to develop lead-free nuclear radiation protection materials. Although these materials do not contain lead, their core components are still heavy metals with potential ecological risks, and they have not fundamentally solved the problem of biological safety and environmental friendliness of the materials. Another researcher has developed an anti-radiation fluorosilicone rubber composite material made of fluorosilicone rubber, reinforcing filler, anti-radiation agent, additive, and vulcanizing agent through high-temperature vulcanization. The reinforcing filler is composed of carbon black, white carbon black, lead oxide, and barium sulfate. Although the retention rate of the tensile strength and resilience performance of the rubber is ≥90%, and the anti-radiation aging performance is excellent, the material still contains lead elements, which does not comply with the green development concept.

[0004] Therefore, it is necessary to design a lead-free electromagnetic-ionizing radiation resistant composite rubber material and a preparation method and application thereof to solve the above problems. SUMMARY

[0005] In view of the technical problems in the background art, the present application provides a lead-free electromagnetic-ionizing radiation resistant composite rubber material and a preparation method and application thereof, aiming to solve the technical problems of existing radiation protection products, such as high density, high toxicity, and poor wearing comfort.

[0006] In a first aspect, the present application provides a preparation method of a lead-free electromagnetic-ionizing radiation resistant composite rubber material, comprising the following steps: S1. Dissolving a bismuth source, a samarium source, and a cerium source in a dilute nitric acid solution to obtain a precursor solution; S2. The precursor solution is sequentially subjected to atomization pyrolysis, calcination, and ultrasonic treatment to obtain ionizing radiation resistant composite particles; S3. A silver layer is coated onto the surface of the anti-ionizing radiation composite particles by chemical reduction to obtain a core-shell structured anti-electromagnetic-ionizing radiation filler. S4. The electromagnetic-ionizing radiation shielding filler is blended with the surface treatment agent and then mixed with the rubber matrix, activator, reinforcing agent, antioxidant, and vulcanizing agent to obtain lead-free electromagnetic-ionizing radiation shielding compound. S5. The lead-free electromagnetic-ionizing radiation shielding compound is vulcanized and molded to obtain a lead-free electromagnetic-ionizing radiation shielding composite rubber material.

[0007] As a further improvement of this application, in step S1, the bismuth source is bismuth nitrate, the samarium source is samarium nitrate, and the cerium source is cerium nitrate; the molar ratio of the bismuth source, samarium source, and cerium source is (4~6):(2~4):(1~3); the pH value of the dilute nitric acid solution is 1~4, and the amount used is 1~3 times the total mass of the bismuth source, samarium source, and cerium source.

[0008] As a further improvement of this application, in step S2, the temperature of the atomization pyrolysis is 400~600℃ and the pyrolysis time is 5~10s; the temperature of the calcination is 500~800℃ and the calcination time is 1~3h; the frequency of the ultrasonic treatment is 40~100kHz and the time is 30~60min.

[0009] As a further improvement of this application, in step S3, the chemical reduction method uses glucose as a reducing agent and AgNO3 solution as a silver source, with a molar ratio of AgNO3 to glucose of 1:(1.5~2), and the silver content in the obtained electromagnetic-ionizing radiation shielding filler is 8~12%.

[0010] As a further improvement of this application, in step S4, the surface treatment agent is maleic anhydride-grafted polyolefin elastomer, and the amount used is 1 to 3% of the mass of the electromagnetic-ionizing radiation shielding filler.

[0011] As a further improvement of this application, based on 100 parts by weight of rubber matrix, the activator is composed of zinc oxide and stearic acid, with the amount of zinc oxide being 2-6 parts by weight and the amount of stearic acid being 1-3 parts by weight; the reinforcing agent is conductive carbon black, with the amount being 5-15 parts by weight; the antioxidant is 4010NA, with the amount being 1-2 parts by weight; and the vulcanizing agent is sulfur, with the amount being 2-4 parts by weight.

[0012] As a further improvement of this application, in the lead-free electromagnetic-ionizing radiation shielding compound, the filling amount of the electromagnetic-ionizing radiation shielding filler is 60~80%.

[0013] As a further improvement of this application, in step S5, the vulcanization molding includes a primary vulcanization at 120~150°C and a secondary vulcanization at 50~70°C.

[0014] Secondly, this application provides a lead-free electromagnetic-ionizing radiation shielding composite rubber material, which is prepared by the method described in the first aspect for preparing the lead-free electromagnetic-ionizing radiation shielding composite rubber material.

[0015] Thirdly, this application provides the application of a lead-free electromagnetic-ionizing radiation shielding composite rubber material in radiation protection equipment, wherein the lead-free electromagnetic-ionizing radiation shielding composite rubber material is used to prepare medical protective products or industrial protective components.

[0016] The beneficial effects of this application are as follows: This application provides a lead-free electromagnetic-ionizing radiation shielding composite rubber material, its preparation method, and its application. A precursor solution is obtained by dissolving a bismuth source, a samarium source, and a cerium source in a dilute nitric acid solution. The precursor solution is then subjected to atomization pyrolysis, calcination, and ultrasonic treatment sequentially to obtain ionizing radiation shielding composite particles. A silver layer is coated onto the surface of the ionizing radiation shielding composite particles using a chemical reduction method to obtain a core-shell structured electromagnetic-ionizing radiation shielding filler. The electromagnetic-ionizing radiation shielding filler is blended with a surface treatment agent, and then compounded with a rubber matrix, activator, reinforcing agent, antioxidant, and vulcanizing agent to obtain a lead-free electromagnetic-ionizing radiation shielding compound. The lead-free electromagnetic-ionizing radiation shielding compound is then vulcanized to obtain the lead-free electromagnetic-ionizing radiation shielding composite rubber material. This application, through innovative material formulation, optimized preparation process, and designed core-shell structured filler, successfully develops an environmentally friendly, efficient, and dual-functional lead-free radiation shielding rubber material. It meets protection requirements while also considering processing and mechanical properties, exhibiting significant technical advantages and broad market application prospects.

[0017] This application utilizes environmentally friendly elements such as bismuth, samarium, and cerium to replace traditional lead-based materials, and combines advanced processes such as atomization pyrolysis, calcination, ultrasonic treatment, and chemical reduction coating of silver layers to prepare a core-shell structured composite filler. This allows the rubber material to simultaneously possess excellent dual functions of protecting against ionizing radiation and electromagnetic radiation. This material is not only green and environmentally friendly, meeting the requirements of sustainable development, but also maintains good mechanical properties, processing performance, and long-term stability. It can be widely used in high-radiation protection fields such as medical, nuclear industry, military, electronic communications, and aerospace.

[0018] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0020] Figure 1 This is a scanning electron microscope image of the anti-ionizing radiation composite particles obtained in Embodiment 1 of this application; Figure 2 This is a scanning electron microscope image of the electromagnetic-ionizing radiation shielding filler obtained in Example 1 of this application; Figure 3 This is a scanning electron microscope image of the surface of the lead-free electromagnetic-ionizing radiation shielding composite rubber material obtained in Example 1 of this application; Figure 4 This is a cross-sectional scanning electron microscope image of the lead-free electromagnetic-ionizing radiation shielding composite rubber material obtained in Example 1 of this application; Figure 5 This is a physical image of the lead-free electromagnetic-ionizing radiation shielding composite rubber material obtained in Example 1 of this application; Figure 6 This is a physical image of a medical electromagnetic-ionizing radiation protective suit made from the lead-free electromagnetic-ionizing radiation protective composite rubber material obtained in Example 1 of this application. Detailed Implementation

[0021] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0023] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0024] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0025] With the continuous advancement of modern nuclear weapons technology and the sustained development of the nuclear industry, radiation hazards caused by nuclear leaks and other issues have become a serious social problem. Currently, lead is the most common radiation protection material on the market. However, due to lead's high biological toxicity, long-term contact or improper handling can easily lead to lead poisoning, posing a serious threat to personnel and the environment. Secondly, lead has an extremely high density, resulting in protective equipment that is exceptionally bulky, uncomfortable, and lacks breathability, flexibility, and rigidity, severely limiting the wearer's mobility and working hours. Furthermore, lead's shielding effect against specific rays such as low-energy X-rays is insufficient, creating blind spots in protection.

[0026] To address the technical problems of existing radiation protection products, such as high density, high toxicity, and poor wearing comfort, this application provides a lead-free electromagnetic-ionizing radiation shielding composite rubber material, its preparation method, and its application. By designing a core-shell structured filler, the material simultaneously possesses the dual functions of shielding against electromagnetic and ionizing radiation. Furthermore, through optimized preparation processes and material formulations, the resulting composite rubber material not only exhibits excellent mechanical properties but also possesses anti-radiation aging characteristics, thereby significantly improving both the protective effect and the wearing comfort and safety of the material.

[0027] In a first aspect, embodiments of this application provide a method for preparing a lead-free electromagnetic-ionizing radiation shielding composite rubber material, comprising the following steps: S1. Dissolve the bismuth source, samarium source, and cerium source in dilute nitric acid solution to obtain a precursor solution; S2. The precursor solution is subjected to atomization pyrolysis, calcination and ultrasonic treatment in sequence to obtain anti-ionizing radiation composite particles; S3. A silver layer is coated onto the surface of the anti-ionizing radiation composite particles by chemical reduction to obtain a core-shell structured anti-electromagnetic-ionizing radiation filler. S4. After blending the anti-electromagnetic-ionizing radiation filler with the surface treatment agent, it is then mixed with the rubber matrix, activator, reinforcing agent, antioxidant, and vulcanizing agent to obtain lead-free anti-electromagnetic-ionizing radiation compound. S5. The lead-free electromagnetic-ionizing radiation shielding compound is vulcanized to obtain a lead-free electromagnetic-ionizing radiation shielding composite rubber material.

[0028] In the technical solution of this application embodiment, firstly, anti-ionizing radiation composite particles are obtained by combining spray pyrolysis and sintering methods; then, by utilizing the reducing property of glucose on silver ammonia complex ions under alkaline conditions, i.e., chemical reduction method, a silver deposition film is formed on the surface of the anti-ionizing radiation composite particles, thus preparing an anti-electromagnetic-ionizing radiation filler with a specific structure, specific composition, and specific size; finally, the self-made anti-electromagnetic-ionizing radiation filler is combined with natural rubber to finally prepare a composite rubber material with excellent and stable electromagnetic-ionizing shielding performance, as well as good mechanical properties and anti-radiation aging characteristics.

[0029] Specifically, since current materials composed of single elements or simple combinations are insufficient to meet the protection requirements in complex radiation environments, this application selects bismuth, samarium, and cerium as the components of the ionizing radiation shielding composite particles. Based on the unique electronic structure and physicochemical properties of rare earth elements, they exhibit broad application potential in the field of radiation protection. Among them, bismuth (Bi) is particularly valuable due to its high ionizing radiation content (9.8 g / cm³). 3 Bismuth's high density and high atomic number result in a larger photoelectric effect and Compton scattering cross section for high-energy rays, leading to a more significant attenuation effect. Compared to traditional lead shielding materials, bismuth's low toxicity is a significant advantage. Furthermore, its melting point of 271.3°C and boiling point of 1560°C exhibit good thermal stability, maintaining structural stability at high temperatures and making it suitable for various radiation environments. Samarium (Sm) has an extremely high thermal neutron absorption cross section, and its high atomic number also gives it some attenuation capability for gamma rays. It can produce a synergistic effect with bismuth, achieving dual shielding against both neutrons and gamma rays. Cerium (Ce) possesses... 3+ / Ce 4+ CeO2's variable valence state can capture free radicals generated by radiation, reduce radiation damage to materials, and thus improve the long-term radiation stability of materials. At the same time, CeO2 itself also has a certain shielding effect on low-energy gamma rays, which can help bismuth and samarium improve the overall radiation shielding effect.

[0030] Furthermore, in some embodiments, in step S1, the bismuth source is bismuth nitrate, the samarium source is samarium nitrate, and the cerium source is cerium nitrate; the molar ratio of the bismuth source, samarium source, and cerium source is (4~6):(2~4):(1~3); the pH value of the dilute nitric acid solution is 1~4, and the amount used is 1~3 times the total mass of the bismuth source, samarium source, and cerium source.

[0031] In the technical solution of this application embodiment, bismuth, samarium, and cerium have the advantages of complementary radiation shielding characteristics, good composite structure stability, and wide process adaptability. By controlling the molar ratio of bismuth, samarium, and cerium sources at (4~6):(2~4):(1~3), efficient synergistic shielding of neutrons and gamma rays can be achieved, forming a composite material with bismuth as the main component and samarium and cerium as auxiliary components, thereby effectively attenuating gamma rays from low to high energy. Since rare earth ions are easily hydrolyzed to form hydroxide precipitates, by selecting dilute nitric acid with a low pH value as the solvent for rare earth nitrates, the hydrolysis reaction can be suppressed, the lattice energy of rare earth salts can be reduced, and their rapid dissolution can be promoted, ensuring that the solution is clear and free of precipitates. At the same time, after atomization, the rare earth nitrate solution is directly converted into rare earth oxides in the pyrolysis furnace. Dilute nitric acid as a solvent can minimize impurity contamination and ensure the high purity of the rare earth salt solution. Specifically, the dissolution of bismuth, samarium, and cerium sources can be accelerated by stirring at a speed of 300-500 rpm for 1-2 hours.

[0032] Furthermore, in some embodiments, in step S2, the temperature of atomization pyrolysis is 400~600℃, and the pyrolysis time is 5~10s; the temperature of calcination is 500~800℃, and the calcination time is 1~3h; the frequency of ultrasonic treatment is 40~100kHz, and the time is 30~60min.

[0033] In the technical solution of this application embodiment, a spray pyrolysis method combined with a sintering process is used to prepare ionizing radiation-resistant particles. Through the synergistic effect of solution atomization-rapid pyrolysis-high-temperature sintering, significant advantages are demonstrated in terms of the uniformity of ionizing radiation-resistant particle composition, controllable morphology, structural stability, and production efficiency, making it suitable for the preparation requirements of Bi-Sm-Ce multi-component composite system ionizing radiation-resistant particles. Specifically, a spray pyrolysis device is used for atomization pyrolysis treatment. The spray pyrolysis device includes a spraying device and a pyrolysis furnace. After the rare earth nitrate precursor solution is atomized under high pressure to form micron-sized droplets, it is rapidly dried and decomposed in the pyrolysis furnace. The rare earth nitrate is simultaneously converted into rare earth oxides. This process ensures that the elemental ratio of each droplet is completely consistent with the mother liquor, avoiding local element enrichment caused by uneven mixing, and fundamentally guaranteeing the compositional uniformity of the multi-component ionizing radiation-resistant composite particles. Simultaneously, the atomized droplets form spherical shapes due to surface tension, directly becoming spherical powders after pyrolysis. Furthermore, by adjusting the atomization parameters and pyrolysis temperature, the particle size can be controlled to meet the needs of different shielding scenarios. The sintering process plays a crucial role in optimizing the crystal structure and radiation shielding performance of spray pyrolysis particles. Particles directly obtained from spray pyrolysis are mostly amorphous or low-crystallinity oxides. High-temperature sintering improves crystal integrity, and the high-crystallinity structure enhances photoelectric absorption of gamma rays. Simultaneously, during sintering, atomic diffusion on the particle surface further smooths the morphology, significantly improving the dispersibility of the filler in the rubber matrix and promoting particle densification. Furthermore, precise adjustment of the secondary particle size can be achieved by controlling the sintering temperature. Specifically, the atomizing gas flow rate is 500–1000 mL / min, the gas is nitrogen, and the injection rate is 1–5 mL / min; the carrier gas in the pyrolysis furnace is nitrogen, with a flow rate of 1–3 L / min, and the preferred residence time of the droplets in the pyrolysis furnace is 5–10 s. The resulting anti-ionizing radiation composite particles are multi-element rare earth oxides.

[0034] Furthermore, in some embodiments, in step S3, the chemical reduction method uses glucose as a reducing agent and AgNO3 solution as a silver source, with a molar ratio of AgNO3 to glucose of 1:(1.5~2), and the silver content in the obtained electromagnetic-ionizing radiation shielding filler is 8~12%.

[0035] In the technical solution of this application embodiment, the chemical reduction method has the advantages of uniform coating, low cost, and low-temperature compatibility. Glucose, as a reducing agent, ensures the quality of the silver layer and the feasibility of the process through its mild reduction, environmental safety, and easy controllability. The combination of the two can efficiently prepare multifunctional core-shell particles that have both anti-ionizing radiation (core) and electromagnetic radiation protection (silver shell). Glucose has moderate reducing properties, which allows silver ions to be slowly reduced on the particle surface, avoiding the generation of free silver particles due to rapid reduction, thereby forming a continuous and dense silver layer and ensuring the continuity of electromagnetic shielding. At the same time, the byproduct of the glucose reduction reaction is gluconate, which is a harmless organic substance and meets environmental protection requirements. Silver is selected as the electromagnetic shielding layer because of its excellent conductivity (conductivity as high as 6.3 × 10⁻⁶). 7 Its shielding relies mainly on reflection loss and absorption loss, which has obvious advantages, especially in high-frequency shielding. Secondly, silver has high chemical stability. It is chemically stable in a dry environment at room temperature and is not easily oxidized or corroded, thus maintaining its conductivity and shielding performance for a long time. At the same time, the silver ammonia complex ion ([Ag(NH3)2]) + In the liquid phase, it can diffuse uniformly and completely coat the anti-ionizing radiation composite particles, ensuring a stable interface between the silver layer and the particles, thus ensuring the continuity and consistency of the material's shielding performance. An appropriate amount of silver allows the silver layers on the particle surface to interconnect, forming a three-dimensional conductive network without significantly reducing the radiation-resistant components of the core particles. Furthermore, silver has an additional shielding effect against low-energy X-rays, which can, to some extent, compensate for the relatively weak shielding ability of rare earth oxides against low-energy rays, achieving synergistic protection against electromagnetic and full-spectrum ionizing radiation. Specifically, the chemical reduction method involves adding the obtained anti-ionizing radiation composite particles to deionized water, slowly adding AgNO3 solution while stirring, followed by glucose solution, adjusting the pH to 7-9 with ammonia, and continuously stirring and heating to 50-70℃. After the reaction is complete, the particles are washed, centrifuged, and dried to obtain the anti-electromagnetic-ionizing radiation filler. The concentration of the mixed solution of anti-ionizing radiation composite particles and deionized water is 4-6%, the concentration of AgNO3 solution is 8-12%, and the mass ratio of the two is (9-15):1; the stirring speed is 300-500 rpm, and the time is 1-2 h; the concentration of glucose solution is 8-12%; the washing process involves washing with deionized water 3-4 times; the centrifugation speed is 7000-8000 rpm, and the time is 10-15 min; the drying process temperature is 50-60℃, and the time is 18-24 h.

[0036] Further, in some embodiments, in step S4, the surface treatment agent is maleic anhydride-grafted polyolefin elastomer (POE-g-MAH), and the amount used is 1-3% of the mass of the electromagnetic radiation shielding filler. Based on 100 parts by weight of rubber matrix, the activator is composed of zinc oxide and stearic acid, with the amount of zinc oxide being 2-6 parts by weight and the amount of stearic acid being 1-3 parts by weight; the reinforcing agent is conductive carbon black, and the amount used is 5-15 parts by weight; the antioxidant is 4010NA, and the amount used is 1-2 parts by weight; the vulcanizing agent is sulfur, and the amount used is 2-4 parts by weight. In the lead-free electromagnetic radiation shielding compound, the filling amount of the electromagnetic radiation shielding filler is 60-80%.

[0037] In the technical solution of this application embodiment, the surface of the electromagnetic-ionizing radiation shielding filler is first pre-treated by coating to ensure that the surface treatment agent fully coats the powder and avoids secondary agglomeration during mixing. Additives such as zinc oxide, stearic acid, sulfur, conductive carbon black, and 4010NA type antioxidant (N-isopropyl-N'-phenyl-p-phenylenediamine) work synergistically to optimize the comprehensive performance of the composite material from multiple dimensions, including vulcanization efficiency, interfacial bonding, mechanical properties, processability, and anti-aging properties. This ensures that the electromagnetic-ionizing radiation shielding filler fully functions while forming a composite material with rubber that exhibits balanced performance. It retains the electromagnetic-ionizing radiation shielding function of the material while possessing the elasticity, processability, and durability of rubber, making it suitable for various application scenarios. Conductive carbon black is selected as a reinforcing agent, whose particles can embed between rubber molecular chains. Through physical adsorption (van der Waals forces) and chemical action (a small number of chemical bonds), the intermolecular bonding force is enhanced, thereby improving the tensile strength of the composite material to meet the structural strength requirements of radiation-resistant products. Adding carbon black increases the surface hardness and abrasion resistance of rubber. Furthermore, the network structure of carbon black can disperse stress concentration, helping to extend the service life of the product. Simultaneously, the active groups on the carbon black surface can form weak interactions with the surface of the anti-ionizing radiation composite particles, thereby reducing powder agglomeration. In addition, the high conductivity of carbon black can cooperate with the silver-coated anti-ionizing radiation composite particles to further improve the electromagnetic shielding performance of the composite material. Specifically, the anti-electromagnetic-ionizing radiation filler and surface treatment agent are mixed in a high-speed mixer at a temperature of 60-80℃, a speed of 1500-2000 r / min, and a mixing time of 5-15 min.

[0038] Furthermore, in some embodiments, in step S5, vulcanization molding includes a primary vulcanization at 120~150°C and a secondary vulcanization at 50~70°C.

[0039] In the technical solution of this application embodiment, the lead-free electromagnetic-ionizing radiation shielding composite rubber material undergoes two vulcanization treatments. Through the synergistic effect of uniform crosslinking, interface strengthening, stress relief, and performance stabilization, the performance shortcomings caused by the high filling amount of electromagnetic-ionizing radiation shielding filler are specifically addressed. This allows the material to maintain its highly efficient electromagnetic-ionizing radiation shielding function while also possessing excellent mechanical properties, dimensional stability, and aging resistance. A high proportion of electromagnetic-ionizing radiation shielding filler can hinder the movement of rubber molecular chains, resulting in insufficient internal crosslinking during the main vulcanization stage, easily leading to stress concentration and weakening the interfacial bonding force. The secondary vulcanization, through low-temperature, long-term heating, avoids local overheating caused by the poor thermal conductivity of the powder and promotes the slow diffusion of unreacted sulfur and accelerators, gradually relaxing the rubber molecular chains and further promoting crosslinking of rubber molecules around the powder. This enhances the chemical bonding between the powder surface and the rubber, reduces interfacial voids, and prevents fracture due to insufficient local crosslinking. Furthermore, the agglomerates of the filler powder are further dispersed during the long-term, gentle heating process, contributing to a more uniform radiation resistance performance. Specifically, the lead-free electromagnetic-ionizing radiation shielding compound is cut into appropriate sizes and placed in a preheated mold. The mold preheating temperature is 100~150℃. The temperature of the first vulcanization process is 120~150℃, and the time is determined by testing with a vulcanizing instrument. The second vulcanization process is as follows: after demolding, the lead-free electromagnetic-ionizing radiation shielding composite rubber is cooled to room temperature and then placed in a forced-air drying oven at 50~70℃ for 2~4 hours.

[0040] Secondly, embodiments of this application provide a lead-free electromagnetic-ionizing radiation shielding composite rubber material, which is prepared by the method for preparing the lead-free electromagnetic-ionizing radiation shielding composite rubber material described in the first aspect.

[0041] In the technical solution of this application embodiment, the lead-free electromagnetic-ionizing radiation-resistant composite rubber material prepared by combining self-made electromagnetic-ionizing radiation-resistant filler with natural rubber achieves the integration of dual functions of anti-ionizing radiation and anti-electromagnetic interference. At the same time, it does not contain lead and has environmentally friendly and non-toxic characteristics. While meeting the requirements of green environmental protection, it also has excellent mechanical properties and good resistance to radiation aging.

[0042] Thirdly, embodiments of this application provide the application of a lead-free electromagnetic-ionizing radiation shielding composite rubber material in radiation protection equipment, which is used to prepare medical protective products or industrial protective components.

[0043] In the technical solutions of this application embodiment, the lead-free electromagnetic-ionizing radiation shielding composite rubber material can be used to prepare medical imaging and radiotherapy protective shielding materials, including but not limited to protective curtains, protective aprons, gloves and other protective devices. As a functional shielding protective material, it is suitable for fields such as nuclear medicine diagnosis and treatment, radiotherapy and interventional radiology.

[0044] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0045] Example 1 This embodiment provides a method for preparing a lead-free electromagnetic-ionizing radiation shielding composite rubber material, including the following steps: S1. 242.5g of bismuth nitrate (Bi(NO3)3·5H2O), 133.31g of samarium nitrate (Sm(NO3)3·6H2O), and 86.82g of cerium nitrate (Ce(NO3)3·6H2O) were added sequentially to 925.26g of dilute nitric acid solution (pH 1). The mixture was stirred at 300rpm for 2h at room temperature until completely dissolved to obtain the precursor solution. S2. The precursor solution was injected into a spray pyrolysis apparatus. The atomizing gas flow rate was set to 800 mL / min, the injection rate to 3 mL / min, the pyrolysis furnace temperature to 500℃, the carrier gas to nitrogen at a flow rate of 2 L / min, and the residence time of the droplets in the pyrolysis furnace to 10 s. The solution was atomized into fine droplets by the atomizer. After thermal decomposition and collection, the resulting powder particles were sintered in a tube furnace at 750℃ for 2 h, followed by ultrasonic treatment at 80 kHz for 45 min to obtain anti-ionizing radiation composite particles. Figure 1 As shown, the obtained anti-ionizing radiation composite particles are spherical particles with relatively uniform dispersion and smooth surface; S3. Add 5g of anti-ionizing radiation composite particles to 95g of deionized water, and slowly add 9.1g of 10% AgNO3 solution while stirring. Then add 14.5g of 10% glucose solution and continue stirring at 300rpm for 2 hours. During this time, raise the temperature of the mixed solution to 60℃ and adjust the pH of the mixed solution to 8 with ammonia. After the reaction is complete, wash the obtained powder 3-4 times with deionized water, centrifuge at 8000rpm for 15min, and dry at 50℃ for 24 hours to obtain a core-shell structured anti-electromagnetic-ionizing radiation filler. Figure 2 As shown, the surface of the obtained electromagnetic-ionizing radiation shielding filler is dispersed with a relatively dense silver coating layer. S4. Add 450g of electromagnetic-ionizing radiation shielding filler and 9g of POE-g-MAH to a mixer, adjust the temperature to 70℃, the speed to 1800r / min, stir and mix for 10min, and then remove and set aside. Use a two-roll mill to plasticize 100g of natural rubber, and then add 400g of the electromagnetic-ionizing radiation shielding filler mixed with POE-g-MAH, 5g of zinc oxide, 2g of stearic acid, 15g of conductive carbon black, 1.5g of antioxidant 4010NA and 2g of sulfur in sequence to obtain lead-free electromagnetic-ionizing radiation shielding compound. S5. Preheat the hot press mold to 100℃, place the lead-free electromagnetic-ionizing radiation shielding compound into it, and after hot pressing and vulcanization at 145℃, demold and cool to room temperature. Then, place it in a forced-air drying oven and treat it at 60℃ for 4 hours to obtain a lead-free electromagnetic-ionizing radiation shielding composite rubber material; Figure 5 As shown, the resulting lead-free electromagnetic-ionizing radiation shielding composite rubber material is generally smooth and even; Figure 3 As shown, the surface of the obtained rubber material has a fine texture, but no large surface defects; as Figure 4 As shown, the electromagnetic-ionizing radiation shielding filler is relatively uniformly dispersed within the rubber, with few interfacial voids. For example... Figure 6 As shown, rubber materials can be processed into medical nuclear radiation protective clothing, which is highly practical.

[0046] Examples 2-3 and Comparative Examples 1-6 Examples 2-3 and Comparative Examples 1-6 respectively provide a method for preparing a lead-free electromagnetic-ionizing radiation shielding composite rubber material. Compared with Example 1, the only difference is that the proportions of bismuth nitrate, samarium nitrate, and cerium nitrate are different in step S1. The other aspects are roughly the same as in Example 1 and will not be repeated here.

[0047] The prepared lead-free electromagnetic-ionizing radiation shielding composite rubber material was processed into samples with dimensions of 15cm × 15cm and a thickness of 2mm. Ionizing radiation shielding tests were conducted according to the method disclosed in YY / T 0292.1-2020 "Medical Diagnostic X-ray Radiation Shielding Apparatus Part 1: Determination of Material Attenuation Performance," where the X-ray tube voltage was 120KV, and lead equivalent refers to the lead layer thickness corresponding to the shielding effect of the shielding material at a specific radiation energy, equivalent to that of a lead plate of a certain thickness. Electromagnetic shielding effectiveness tests were conducted according to the method disclosed in GB / T 30142-2013 "Measurement Method for Shielding Effectiveness of Planar Electromagnetic Shielding Materials," where the samples were tested in the X-ray band (8~12GHz).

[0048] The tensile strength and elongation at break of the obtained rubber materials were tested according to the methods disclosed in GB / T 528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber", and the resilience of the obtained rubber materials was tested according to the methods disclosed in GB / T 1681-2009 "Determination of resilience of vulcanized rubber".

[0049] The performance of the lead-free electromagnetic-ionizing radiation shielding composite rubber materials prepared in Examples 1-3 and Comparative Examples 1-6 was tested, and the results are shown in Table 1.

[0050] Table 1. Properties of lead-free electromagnetic-ionizing radiation shielding composite rubber materials in Examples 1-3 and Comparative Examples 1-6 As shown in Table 1, since the total amount of filler remains constant, the tensile strength, elongation at break, resilience, and electromagnetic shielding effectiveness of the prepared rubber material fluctuate within a certain range, with little overall change and relatively stable performance. However, the lead equivalent of the obtained rubber material varies significantly. When the bismuth content in the filler decreases, the lead equivalent is lower. This is because bismuth has the highest Z (atomic coefficient) and is the main attenuating component, with a larger photoelectric effect and Compton scattering cross section for high-energy photons, resulting in significantly stronger absorption capacity. Although samarium and cerium have slightly lower atomic coefficients and lower absorption capacity than bismuth, they can help cover the energy range where bismuth has not completely attenuated. Only when the three components work synergistically in an appropriate ratio can the coverage range of radiation energy be broadened and the overall radiation resistance efficiency improved. Too high or too low a concentration of any one component will affect the radiation resistance efficiency.

[0051] Examples 4-5 and Comparative Examples 7-8 Examples 4-5 and Comparative Examples 7-8 respectively provide a method for preparing a lead-free electromagnetic-ionizing radiation shielding composite rubber material. Compared with Example 1, the only difference is that the content of Ag in the electromagnetic-ionizing radiation shielding filler is different in step S3. The other methods are roughly the same as those in Example 1 and will not be described again here.

[0052] The lead-free electromagnetic-ionizing radiation shielding composite rubber materials prepared in Examples 4-5 and Comparative Examples 7-8 were subjected to performance tests, and the results are shown in Table 2.

[0053] Table 2. Properties of lead-free electromagnetic-ionizing radiation shielding composite rubber materials in Examples 4-5 and Comparative Examples 7-8 As shown in Table 2, since the total amount of filler remains constant, the prepared rubber material exhibits slight fluctuations within a certain range in terms of tensile strength, elongation at break, resilience, and electromagnetic shielding effectiveness, demonstrating relatively stable overall performance. However, the silver content has a significant impact on lead equivalent and electromagnetic shielding effectiveness: when the silver content is low, the silver layer on the powder surface is discontinuous, existing mostly as isolated particles or localized small-scale coatings, failing to form a complete conductive network. In this case, electromagnetic shielding relies mainly on a small amount of reflection and absorption, resulting in a low shielding effectiveness. Conversely, when the silver content is too high, an excessively thick silver layer can cause particle agglomeration, leading to silver layer stacking on the powder particle surface. This not only disrupts the uniformity of the conductive network but also increases interfacial stress, resulting in localized electromagnetic wave leakage. Furthermore, excessive silver occupies part of the volume of the anti-ionizing radiation particles, reducing the content of high-Z elements per unit volume, thus slightly decreasing the lead equivalent and further affecting the uniformity of radiation attenuation.

[0054] Examples 6-7 and Comparative Examples 9-10 Examples 6-7 and Comparative Examples 9-10 respectively provide a method for preparing a lead-free electromagnetic-ionizing radiation shielding composite rubber material. Compared with Example 1, the only difference is that the weight of conductive carbon black is different in step S4. The other steps are roughly the same as in Example 1 and will not be described again here.

[0055] The lead-free electromagnetic-ionizing radiation shielding composite rubber materials prepared in Examples 6-7 and Comparative Examples 9-10 were subjected to performance tests, and the results are shown in Table 3.

[0056] Table 3. Properties of lead-free electromagnetic-ionizing radiation shielding composite rubber materials in Examples 6-7 and Comparative Examples 9-10 Table 3 shows that the content of conductive carbon black has a significant impact on the tensile strength of the composite rubber material. When the carbon black content is low, the particles are uniformly dispersed and can embed themselves in the gaps between rubber molecular chains. Through van der Waals forces, the bonding force between molecules is enhanced, resulting in a slight increase in tensile strength with increasing content. Furthermore, the three-dimensional conductive network formed by the overlapping carbon black particles can synergistically enhance electromagnetic shielding effectiveness with silver. However, when the carbon black content is high, severe agglomeration occurs, leading to stress concentration. Microcracks easily form at the edges of the agglomerates, causing a decrease in tensile strength. Simultaneously, rigid agglomerates hinder the elastic recovery of molecular chains, reducing resilience. Excessive carbon black also restricts molecular chain movement, increasing the brittleness of the rubber matrix and significantly reducing elongation at break. Additionally, excessive carbon black agglomeration can cause localized short circuits or breaks in the conductive network, resulting in a slight decline in shielding effectiveness.

[0057] Examples 8-9 and Comparative Examples 11-13 Examples 8-9 and Comparative Examples 11-13 respectively provide a method for preparing a lead-free electromagnetic-ionizing radiation shielding composite rubber material. Compared with Example 1, the only difference is that the filling amount of electromagnetic-ionizing radiation shielding filler is different in step S4. The other methods are roughly the same as those in Example 1 and will not be described again here.

[0058] The lead-free electromagnetic-ionizing radiation shielding composite rubber materials prepared in Examples 8-9 and Comparative Examples 11-13 were subjected to performance tests, and the results are shown in Table 4. This indicates that rubber material cannot be prepared.

[0059] Table 4. Properties of lead-free electromagnetic-ionizing radiation shielding composite rubber materials in Examples 8-9 and Comparative Examples 11-13 As shown in Table 4, with the increase of the filler content for electromagnetic-ionizing radiation protection, the number of components with anti-ionization and electromagnetic shielding functions in the composite rubber also increases accordingly, resulting in a gradual improvement in lead equivalent and electromagnetic shielding effectiveness. When the filler content is appropriate, it can enhance the interfacial bonding force between the filler and the rubber substrate, and the tensile strength will gradually increase with the increase of the filler content. However, if too much filler is added, it is easy to cause powder agglomeration, which in turn restricts the movement of rubber molecular chains, leading to increased matrix brittleness. Tensile strength, elongation at break, and resilience will all decrease significantly, and in severe cases, it may even prevent the rubber from being molded.

[0060] Example 10 The lead-free electromagnetic-ionizing radiation shielding composite rubber material prepared in Example 1 was subjected to X-ray irradiation with a cumulative dose of 6 × 10⁻⁶. 7 After rad irradiation aging, its performance is shown in Table 5.

[0061] Table 5. Performance of Lead-Free Electromagnetic-Ionizing Radiation Shielding Composite Rubber Material in Example 10 As shown in Table 5, after irradiation aging test, the prepared lead-free electromagnetic-ionizing radiation shielding composite rubber material retains tensile strength, elongation at break, and resilience of ≥80%, lead equivalent retention rate of ≥95%, and electromagnetic shielding effectiveness retention rate of ≥85%, which shows that the rubber material has excellent anti-radiation aging performance.

[0062] In summary, the lead-free electromagnetic-ionizing radiation shielding composite rubber material prepared in this application exhibits a lead equivalent of up to 0.545 mmPb at 120 kV, an electromagnetic shielding effectiveness of 42 dB at 8–12 GHz, a tensile strength of 9.53 MPa, an elongation at break of 198%, and a resilience of 65%, while also possessing excellent resistance to radiation aging. This application successfully integrates the dual functions of ionizing radiation protection and electromagnetic shielding. Because the material is lead-free, it is environmentally friendly and non-toxic, meeting both green environmental protection requirements and possessing excellent mechanical properties and good resistance to radiation aging. Therefore, it can be widely used in complex scenarios such as nuclear power plants and medical applications.

[0063] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for preparing a lead-free electromagnetic-ionizing radiation shielding composite rubber material, characterized in that, Includes the following steps: S1. Dissolve the bismuth source, samarium source, and cerium source in dilute nitric acid solution to obtain a precursor solution; S2. The precursor solution is subjected to atomization pyrolysis, calcination and ultrasonic treatment in sequence to obtain anti-ionizing radiation composite particles; S3. A silver layer is coated onto the surface of the anti-ionizing radiation composite particles by chemical reduction to obtain a core-shell structured anti-electromagnetic-ionizing radiation filler. S4. The electromagnetic-ionizing radiation shielding filler is blended with the surface treatment agent and then mixed with the rubber matrix, activator, reinforcing agent, antioxidant, and vulcanizing agent to obtain lead-free electromagnetic-ionizing radiation shielding compound. S5. The lead-free electromagnetic-ionizing radiation shielding compound is vulcanized and molded to obtain a lead-free electromagnetic-ionizing radiation shielding composite rubber material.

2. The method for preparing the lead-free electromagnetic-ionizing radiation shielding composite rubber material according to claim 1, characterized in that, In step S1, the bismuth source is bismuth nitrate, the samarium source is samarium nitrate, and the cerium source is cerium nitrate; the molar ratio of the bismuth source, samarium source, and cerium source is (4~6):(2~4):(1~3); the pH value of the dilute nitric acid solution is 1~4, and the amount used is 1~3 times the total mass of the bismuth source, samarium source, and cerium source.

3. The method for preparing the lead-free electromagnetic-ionizing radiation shielding composite rubber material according to claim 1, characterized in that, In step S2, the temperature of the atomization pyrolysis is 400~600℃ and the pyrolysis time is 5~10s; the temperature of the calcination is 500~800℃ and the calcination time is 1~3h; the frequency of the ultrasonic treatment is 40~100kHz and the time is 30~60min.

4. The method for preparing the lead-free electromagnetic-ionizing radiation shielding composite rubber material according to claim 1, characterized in that, In step S3, the chemical reduction method uses glucose as a reducing agent and AgNO3 solution as a silver source. The molar ratio of AgNO3 to glucose is 1:(1.5~2), and the silver content in the obtained electromagnetic-ionizing radiation shielding filler is 8~12%.

5. The method for preparing the lead-free electromagnetic-ionizing radiation shielding composite rubber material according to claim 1, characterized in that, In step S4, the surface treatment agent is maleic anhydride-grafted polyolefin elastomer, and the amount used is 1 to 3% of the mass of the electromagnetic-ionizing radiation shielding filler.

6. The method for preparing the lead-free electromagnetic-ionizing radiation shielding composite rubber material according to claim 5, characterized in that, Based on 100 parts by weight of a rubber matrix, the activator is composed of zinc oxide and stearic acid, with zinc oxide used in an amount of 2-6 parts by weight and stearic acid used in an amount of 1-3 parts by weight; the reinforcing agent is conductive carbon black used in an amount of 5-15 parts by weight; the antioxidant is 4010NA used in an amount of 1-2 parts by weight; and the vulcanizing agent is sulfur used in an amount of 2-4 parts by weight.

7. The method for preparing the lead-free electromagnetic-ionizing radiation shielding composite rubber material according to claim 5, characterized in that, In the lead-free electromagnetic-ionizing radiation shielding compound, the filling amount of the electromagnetic-ionizing radiation shielding filler is 60~80%.

8. The method for preparing the lead-free electromagnetic-ionizing radiation shielding composite rubber material according to claim 1, characterized in that, In step S5, the vulcanization molding includes a primary vulcanization at 120~150°C and a secondary vulcanization at 50~70°C.

9. A lead-free composite rubber material for shielding against electromagnetic and ionizing radiation, characterized in that, The lead-free electromagnetic-ionizing radiation shielding composite rubber material is prepared by any one of claims 1-8.

10. The application of the lead-free electromagnetic-ionizing radiation shielding composite rubber material as described in claim 9 in radiation protection equipment, characterized in that, The lead-free electromagnetic-ionizing radiation shielding composite rubber material is used to manufacture medical protective equipment or industrial protective components.

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