A tungsten-containing lead-free radiation-proof rubber glove and its preparation method

Abstract

The present invention relates to the technical field of polymer materials, and specifically to a tungsten-containing lead-free radiation-proof rubber glove and a preparation method thereof. The present invention overcomes the disadvantages of poor radiation-proof ability and poor anti-permeability performance. After the modified ethylene propylene diene monomer rubber is plastified, an activator and an antioxidant are added for the first stage of internal mixing, then carbon black, a composite reinforcing agent, a radiation shielding powder, and a dispersant are added for the second stage of internal mixing, and finally paraffin oil is added for the third stage of internal mixing to obtain a crude mixed rubber; the crude mixed rubber, the radiation shielding powder, the dispersant, a vulcanizing agent, and a vulcanization aid are mixed and open-milled to obtain a rubber sheet; after the rubber sheet is parked, filtered, injection molded, second-stage vulcanized, cleaned, and dried, a tungsten-containing lead-free radiation-proof rubber glove is obtained. The tungsten-containing lead-free radiation-proof rubber glove prepared by the present invention has strong radiation-proof performance and strong anti-permeability performance, and is suitable for the protection of complex radiation environments.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly to a tungsten-containing lead-free radiation protection rubber glove and a preparation method thereof. Background Art

[0002] Radiation protection rubber gloves are widely used in medical radiology departments, nuclear industry production, industrial non-destructive testing, radioactive substance handling and other fields, providing an important radiation protection barrier for practitioners. At present, radiation protection gloves on the market often contain a variety of metals to enhance the protection effect, and common ones include lead, tungsten, bismuth, barium, antimony, etc. Among them, lead was widely used due to its good radiation protection performance, but lead is a heavy metal and is prone to precipitation during production, use and waste treatment, and enters the human body through skin contact, respiratory inhalation and other channels, causing damage to the nervous system, blood system and digestive system, and endangering human health.

[0003] Compared with lead-containing radiation protection gloves, tungsten-containing protection gloves have obvious advantages. Tungsten has a high density, a large atomic number, excellent radiation protection performance, and stable chemical properties, is not easy to precipitate, and has little harm to human health, and has gradually become an ideal substitute material for lead. However, existing tungsten-containing lead-free radiation protection rubber gloves still have deficiencies. In complex application environments such as medical and nuclear industries, the radiation protection performance of such gloves still has a gap compared with lead-containing gloves, and it is difficult to meet the long-term protection requirements in high radiation dose environments; at the same time, in corrosive environments such as acids and alkalis, its anti-permeability performance is poor, and acid-base media are easy to penetrate the rubber matrix, corroding the internal protection material, resulting in a decline in radiation protection performance and shortening the service life of the gloves.

[0004] Therefore, developing a tungsten-containing lead-free radiation protection rubber glove with excellent radiation protection performance and strong anti-permeability performance is of great significance for ensuring the safety of practitioners and promoting the development of related industries.

[0005] For this reason, a tungsten-containing lead-free radiation protection rubber glove and a preparation method thereof are proposed. Summary of the Invention

[0006] The purpose of the present invention is to provide a tungsten-containing lead-free radiation protection rubber glove and a preparation method thereof. After the modified ethylene propylene diene monomer rubber is plastically refined, an activator and an antioxidant are added for the first stage of internal mixing, then carbon black, a composite reinforcing agent, a radiation shielding powder and a dispersant are added for the second stage of internal mixing, and finally paraffin oil is added for the third stage of internal mixing to obtain a crude mixed rubber; the crude mixed rubber, the radiation shielding powder, the dispersant, a vulcanizing agent and a vulcanization aid are mixed and open-milled to obtain a rubber sheet; after the rubber sheet is parked, filtered, injection molded, second-stage vulcanized, cleaned and dried, a tungsten-containing lead-free radiation protection rubber glove is obtained. The tungsten-containing lead-free radiation protection rubber glove prepared by the present invention has strong radiation protection performance and strong anti-permeability performance, and is suitable for the protection of complex radiation environments.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] On the one hand, the present invention provides a preparation method of a tungsten-containing lead-free radiation shielding rubber glove, and the specific preparation steps are as follows:

[0009] Prepare a radiation shielding powder from nano tungsten powder and γ-methacryloxypropyltrimethoxysilane as raw materials;

[0010] React ethylene propylene diene monomer rubber with glycidyl methacrylate to prepare a modified ethylene propylene diene monomer rubber;

[0011] Prepare a composite reinforcing agent from precipitated silica and aramid pulp as raw materials;

[0012] After the modified ethylene propylene diene monomer rubber is plasticized, add an activator and an antioxidant for the first stage of internal mixing, then add carbon black, the composite reinforcing agent, the radiation shielding powder, and a dispersant for the second stage of internal mixing, and finally add paraffin oil for the third stage of internal mixing to obtain a crude mixed rubber;

[0013] Mix the crude mixed rubber, the radiation shielding powder, the dispersant, a vulcanizing agent, and a vulcanization aid by open mixing to obtain a rubber sheet; filter, injection mold, two-stage vulcanize, wash, and dry the rubber sheet to obtain a tungsten-containing lead-free radiation shielding rubber glove.

[0014] Preferably, the preparation method of the modified ethylene propylene diene monomer rubber is as follows: by weight, feed 95-105 parts of ethylene propylene diene monomer rubber into a twin-screw extruder; simultaneously inject a mixture of 5-7 parts of glycidyl methacrylate and 2,5-dimethyl-2,5-di-tert-butylperoxyhexane; the screw speed is 250-300 rpm; the molten modified ethylene propylene diene monomer rubber is extruded, cooled, pelletized, and dried to obtain the modified ethylene propylene diene monomer rubber.

[0015] Preferably, the preparation method of the radiation shielding powder is as follows: disperse nano tungsten powder in dilute nitric acid solution, stir, centrifuge, wash, and dry to obtain acidified pretreated nano tungsten powder; disperse the acidified pretreated nano tungsten powder in a mixed solution composed of anhydrous ethanol and deionized water; after ultrasonic dispersion, adjust the pH value to 4.5-5.5 with dilute hydrochloric acid solution to obtain a suspension; add γ-methacryloxypropyltrimethoxysilane to the suspension, stir and react for 2-2.5 hours; after the reaction, centrifuge, wash, and dry to obtain the radiation shielding powder.

[0016] Preferably, by weight, the addition amount of γ-methacryloxypropyltrimethoxysilane is 4-6% of the acidified pretreated nano tungsten powder.

[0017] Preferably, the preparation method of the composite reinforcing agent is as follows: modified precipitated silica is prepared by reacting precipitated silica with γ-methacryloxypropyltrimethoxysilane; modified aramid pulp is prepared by acidifying aramid pulp with dilute nitric acid; the modified precipitated silica and the modified aramid pulp are mixed in a weight ratio of 9-11:1 to obtain the composite reinforcing agent.

[0018] Preferably, the preparation method of the crude mixed rubber is as follows:

[0019] The temperature of plasticizing is 70-80 °C, and the time of plasticizing is 8-10 min;

[0020] The temperature of the first stage of internal mixing is 80-90 °C, and the time of the first stage of internal mixing is 6-8 min;

[0021] The temperature of the second stage of internal mixing is 80-90 °C, and the time of the second stage of internal mixing is 10-15 min;

[0022] The temperature of the third stage of internal mixing is 90-100 °C, and the time of the third stage of internal mixing is 5-9 min.

[0023] Preferably, the preparation method of the rubber sheet is as follows: by weight, the crude mixed rubber is transferred to an open mill with a roll temperature of 30 °C - 40 °C; radiation shielding powder and dispersant are added in portions on the open mill, and then 8-12 parts of vulcanizing agent and 3-4 parts of vulcanization aid are added; continue to cut, turn, and calender the rubber repeatedly to obtain the rubber sheet.

[0024] Preferably, the two-stage vulcanization process is as follows: the rubber sheet is filtered to obtain a rubber strip, the rubber strip is preheated and formed and then subjected to primary vulcanization, the set temperature is 155-165 °C, the pressure is 30 MPa, and it is maintained for 8-10 min; after the primary vulcanized glove is cooled, it is subjected to secondary vulcanization, the secondary vulcanization temperature is 130-140 °C, and the secondary vulcanization time is 30-40 min.

[0025] On the other hand, the present invention provides a tungsten-containing lead-free radiation-proof rubber glove. The raw materials for preparing the tungsten-containing lead-free radiation-proof rubber glove include: modified ethylene propylene diene monomer rubber, activator, antioxidant, carbon black, composite reinforcing agent, radiation shielding powder, dispersant, paraffin oil, vulcanizing agent, vulcanization aid;

[0026] The activator is a mixture of zinc oxide and stearic acid; the antioxidant is antioxidant 1010; the carbon black is carbon black N660; the vulcanizing agent is dicumyl peroxide; the vulcanization aid is triallyl isocyanurate.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1. In the present invention, the modified nano tungsten powder reduces the surface energy and introduces reactive functional groups. In combination with the wetting and lubricating effects of dispersants such as zinc stearate and glycerol monostearate, through fine mixing by internal mixing and open mixing, its uniform dispersion is promoted to the greatest extent. This highly dispersed system synergizes with the modified ethylene propylene diene monomer (EPDM) rubber matrix to build a strong covalent interface during vulcanization, realizing the firm anchoring of nano tungsten powder. The excellent dispersion uniformity ensures uniform and reliable radiation protection performance, and the strong interfacial bonding enhances the mechanical anti-permeation performance.

[0029] 2. In the present invention, the modified rubber improves the compatibility and reactivity with the modified filler, and forms a firm interface with the active groups on the filler surface and silane through multiple covalent bonds during the vulcanization stage, constructing a strong integrated crosslinked network. The primary and secondary vulcanization further cures and perfects this network. The strong filler-rubber interfacial bonding can efficiently transfer stress, significantly improving the mechanical properties and enhancing puncture resistance; at the same time, it forms a dense chemical permeation barrier, greatly enhancing the anti-permeation performance.

[0030] 3. In the present invention, silane-modified silica introduces reactive functional groups, and acidified aramid pulp introduces polar reactive groups. Through the interaction and chemical bonding between the treated precipitated silica and aramid pulp, the aramid fibers act as bridges to construct a more robust multi-scale composite filler network. The composite reinforcing agent is chemically bonded to the modified rubber matrix and firmly anchored in the rubber network. This synergistic network significantly improves the puncture and tear resistance of the material.

[0031] 4. In the present invention, the processing aids reduce the viscosity, improve wetting and lubrication, and synergistically promote the uniform dispersion of the filler through multi-stage mixing; the filtration process removes impurities and large agglomerates, improving the purity and uniformity of the mixed rubber and ensuring the quality before vulcanization. These processing optimizations ensure the highly uniform dispersion of the filler, achieving uniform radiation protection; the high purity and uniformity of the rubber compound combined with the strong interface reduce defects, enhancing the anti-permeation performance; the highly uniform dispersion of the filler and the defect-free matrix enable effective stress transfer, improving the mechanical properties and enhancing puncture resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a product diagram of the tungsten-containing lead-free radiation protection rubber glove of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0033] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0034] Please refer to Figure 1, the present invention provides a tungsten-containing lead-free radiation-shielding rubber glove and its preparation method, and the technical solution is as follows:

[0035] Example 1

[0036] Preparation of modified ethylene propylene diene monomer (EPDM) rubber

[0037] Feed 95 parts of EPDM rubber continuously into the main feeding port of a twin-screw extruder; simultaneously inject a mixture of 5 parts of glycidyl methacrylate and 0.5 part of 2,5-dimethyl-2,5-di-tert-butylperoxyhexane into the third temperature zone of the barrel through a liquid injection pump; set the temperatures of each temperature zone of the twin-screw extruder barrel to 80°C, 150°C, 180°C, 200°C, 210°C, 210°C, 200°C, 200°C in sequence, the screw speed is 250 rpm; and perform vacuum exhaust in the seventh temperature zone; the molten modified EPDM rubber is extruded from a 200°C die head; the extrudate is cooled by a water bath and then sent to a pelletizer for cutting; obtain glycidyl methacryloxy grafted modified EPDM rubber.

[0038] Preparation of radiation shielding powder

[0039] Disperse 400 parts of nano tungsten powder with a particle size of 30 - 50 nm in 2000 parts of a 5% mass fraction dilute nitric acid solution; continuously stir at room temperature for 30 min, then perform centrifugal separation and washing until the pH value of the washing liquid is neutral, dry the centrifugal precipitate in a vacuum oven at 80°C for 12 hours to obtain acidified pretreated nano tungsten powder; disperse 400 parts of acidified pretreated nano tungsten powder in a mixed solution composed of 2000 parts of absolute ethanol and 20 parts of deionized water, and perform ultrasonic dispersion for 20 min; slowly add 1% mass fraction dilute hydrochloric acid to adjust the pH value of the system to 4.5; add 4% by weight of γ-methacryloxypropyltrimethoxysilane of the acidified pretreated nano tungsten powder to the suspension; heat the system to 60°C and continuously stir and react for 2 hours; after the reaction, perform centrifugal separation and washing until the pH value of the washing liquid is neutral, and dry in a vacuum oven at 80°C for 12 hours; obtain radiation shielding powder.

[0040] Preparation of composite reinforcing agent

[0041] Disperse 40 parts of precipitated silica in a mixed solution composed of 400 parts of absolute ethanol and 0.5 part of deionized water, and form a uniform suspension through ultrasonic dispersion for 30 minutes. Under continuous stirring, add an absolute ethanol solution of 3 parts of γ-methacryloxypropyltrimethoxysilane to the suspension. Stir and react at 60°C for 2 hours. After the reaction, perform centrifugal separation and washing, repeat 2 times, and then dry the centrifuged solid in a vacuum oven at 80°C for 12 hours to obtain modified precipitated silica.

[0042] 100 parts of aramid pulp are ultrasonically dispersed in 2000 parts of a 10% by mass dilute nitric acid solution to form a suspension system. Stir and react at 60 °C for 2 hours. After the reaction, centrifuge and separate, wash, and repeat 2 times. Then dry the centrifuged solid in a vacuum oven at 80 °C for 12 hours to obtain modified aramid pulp.

[0043] The modified precipitated silica and the modified aramid pulp are mixed in a weight ratio of 9:1 to obtain 30 parts of a composite reinforcing agent.

[0044] Plasticate 100 parts of modified ethylene propylene diene monomer (EPDM) rubber in a mixer at a temperature of 70 °C for 8 minutes.

[0045] The plasticated rubber compound is mixed for the first time in a mixer at a temperature of 80 °C, adding 5 parts of zinc oxide, 1 part of stearic acid, 1 part of antioxidant 1010, and 3 parts of calcium oxide, for 6 minutes.

[0046] The rubber compound after the first mixing in the mixer is transferred to the second mixing in the mixer at a temperature of 80 °C, adding 30 parts of carbon black N660, 30 parts of the composite reinforcing agent, 150 parts of surface-modified nano tungsten powder, and 2.5 parts of monoglyceryl stearate, for 10 minutes. The rubber compound after the second mixing in the mixer is transferred to the third mixing in the mixer at a temperature of 90 °C, adding 40 parts of paraffin oil, for 5 minutes, to obtain a roughly mixed rubber compound.

[0047] Transfer the roughly mixed rubber compound to an open mill with a roll temperature of 30 °C. Add the remaining 250 parts of surface-modified nano tungsten powder for radiation shielding and 2.5 parts of monoglyceryl stearate as a dispersant in 5 portions on the open mill, with an interval of 2 minutes each time. Disperse by repeatedly cutting, turning, and calendering the rubber. After adding the radiation shielding powder and monoglyceryl stearate, add 10 parts of dicumyl peroxide with a 40% content and 2 parts of triallyl isocyanurate. Continue to repeatedly cut, turn, and calender for dispersion. The entire mixing and feeding process on the open mill lasts for 35 minutes. Finally, calender it into a film with a thickness of 8 mm - 10 mm.

[0048] Thermally treat the film on the open mill at 60 °C. When the wrapped roll rubber is flat and smooth, start to wind it up. The diameter of the rubber roll ≤ 190 mm, and the length ≤ 800 mm. Push the rubber roll into a plunger-type precision preforming machine equipped with a 150# filter screen to extrude a rubber strip with a cross-sectional size of 50 × 20 mm, and let it cool naturally to room temperature.

[0049] Preheat the rubber strip to 70°C and then inject it into the mold cavity for injection molding; conduct the first vulcanization, set the temperature at 155°C, the pressure at 30 MPa, and hold for 10 min; cool the gloves after the first vulcanization; conduct the second vulcanization on the gloves qualified in the first vulcanization, set the temperature at 130°C, introduce compressed air with a pressure of 0.4 MPa, and hold the vulcanization time for 30 min. Finally, wash the gloves after the second vulcanization with clean water, and then dry them at 70°C for 40 min to obtain the tungsten-containing lead-free radiation-shielding rubber gloves.

[0050] The difference between Example 2 and Example 1 lies in that in the preparation of the radiation shielding powder, the mass fraction of the dilute nitric acid solution is 5.5%; the stirring reaction is carried out for 2.3 hours; the addition amount of γ-methacryloxypropyltrimethoxysilane is 5% of the mass of the acidified pretreated nano-tungsten powder.

[0051] The difference between Example 3 and Example 1 lies in that in the preparation of the radiation shielding powder, the mass fraction of the dilute nitric acid solution is 8%; the stirring reaction is carried out for 2.5 hours; the addition amount of γ-methacryloxypropyltrimethoxysilane is 6% of the mass of the acidified pretreated nano-tungsten powder.

[0052] The difference between Example 4 and Example 2 lies in that in the preparation of the modified ethylene propylene diene monomer rubber, the amount of ethylene propylene diene monomer rubber used is 100 parts, and the addition amount of glycidyl methacrylate is 6 parts of the ethylene propylene diene monomer rubber; the screw speed is 275 rpm; in the preparation of the film, 9.5 parts of vulcanizing agent are added; 3.5 parts of vulcanization aids are added; in the two-stage vulcanization, the temperature of the first vulcanization is maintained at 160°C for 9 min; the temperature of the second vulcanization is 135°C and the second vulcanization time is 25 min.

[0053] The difference between Example 5 and Example 2 lies in that in the preparation of the modified ethylene propylene diene monomer rubber, the amount of ethylene propylene diene monomer rubber used is 105 parts, and the addition amount of glycidyl methacrylate is 7 parts of the ethylene propylene diene monomer rubber; the screw speed is 300 rpm; in the preparation of the film, 12 parts of vulcanizing agent are added; 4 parts of vulcanization aids are added; in the two-stage vulcanization, the temperature of the first vulcanization is maintained at 165°C for 8 min; the temperature of the second vulcanization is 140°C and the second vulcanization time is 20 min.

[0054] The difference between Example 6 and Example 4 lies in that in the preparation of the composite reinforcing agent, the weight ratio of the modified precipitated silica to the modified aramid pulp is 10:1.

[0055] The difference between Example 7 and Example 4 lies in that in the preparation of the composite reinforcing agent, the weight ratio of the modified precipitated silica to the modified aramid pulp is 11:1.

[0056] Example 8 is different from Example 6 in that in the preparation of the crude mixed rubber, the plasticizing temperature is 75°C for 9 minutes; the temperature of the first mixing is 85°C for 7 minutes; the temperature of the second mixing is 85°C for 12.5 minutes; the temperature of the third mixing is 95°C for 7 minutes; in the preparation of the film, the temperature of the roller is 35°C.

[0057] Example 9 is different from Example 6 in that in the preparation of the crude mixed rubber, the plasticizing temperature is 80°C for 10 minutes; the temperature of the first mixing is 90°C for 8 minutes; the temperature of the second mixing is 90°C for 15 minutes; the temperature of the third mixing is 100°C for 9 minutes; in the preparation of the film, the temperature of the roller is 40°C.

[0058] The difference between Comparative Example 1 and Example 1 is only that: the radiation shielding powder uses nano tungsten powder without any treatment.

[0059] The difference between Comparative Example 2 and Example 1 is only that: in the preparation process of the radiation shielding powder, the nano tungsten powder is not pretreated by acidification with dilute nitric acid.

[0060] The difference between Comparative Example 3 and Example 1 is only that: in the preparation process of the radiation shielding powder, the pH is not adjusted when preparing the suspension of the acidified pretreated nano tungsten powder.

[0061] The difference between Comparative Example 4 and Example 1 is only that: the ethylene propylene diene monomer rubber is not modified.

[0062] The difference between Comparative Example 5 and Example 1 is only that: in the preparation process of the modified ethylene propylene diene monomer rubber, the screw speed is 150 rpm.

[0063] The difference between Comparative Example 6 and Example 1 is only that: in the open mill step, the above-mentioned vulcanization aid is not added.

[0064] The difference between Comparative Example 7 and Example 1 is only that: one-stage vulcanization is carried out and the second-stage vulcanization step is removed.

[0065] The difference between Comparative Example 8 and Example 1 is only that: the composite reinforcing agent is not added.

[0066] The difference between Comparative Example 9 and Example 1 is only that: the modified precipitated silica in the composite reinforcing agent is removed.

[0067] The difference between Comparative Example 10 and Example 1 is only that: the modified aramid pulp in the composite reinforcing agent is removed.

[0068] The difference between Comparative Example 11 and Example 1 is only that: the radiation shielding powder is not added in stages, but all the radiation shielding powder and dispersant originally used in the second stage of internal mixing and open mill are added in the second stage of internal mixing.

[0069] The only difference between Comparative Example 12 and Example 1 is that the radiation shielding powder and the dispersant are added at once during the initial milling stage.

[0070] The only difference between Comparative Example 13 and Example 1 is that no dispersant is added in the second internal mixing and open mixing stages.

[0071] The difference between Comparative Example 14 and Example 1 is that the filtering step is removed.

[0072] Comparative Example 15 is different from Example 1 only in that the EPDM rubber is not subjected to modification treatment, and in the mastication step, the EPDM rubber and glycidyl methacrylate are added into the masticator together.

[0073] The only difference between Comparative Example 16 and Example 1 is that the composite reinforcing agent is a composite reinforcing agent obtained by mixing unmodified precipitated silica and unmodified aramid pulp in a weight ratio of 9:1.

[0074] Test Example 1

[0075] Test objects: rubber gloves prepared in Examples 1-3 and Comparative Examples 1-3.

[0076] Test method: Tested in accordance with GBZ / T147-2002 standard. The final test results are shown in Table 1.

[0077] Table 1 Radiation protection performance test results

[0078]

[0079] The surface activity of nano-tungsten powder is improved through acid pretreatment and silane modification. The dispersant and staged internal mixing and opening mixing process are used to promote the uniform dispersion of nano-tungsten powder and form a strong interface with the modified rubber during vulcanization, ensuring the uniform distribution and anchoring of high-density fillers, thereby achieving uniform radiation protection and improving mechanical anti-penetration properties.

[0080] In Comparative Example 1, nano tungsten powder without any treatment was used. Its high surface energy and cohesive force made it difficult to disperse uniformly, and its compatibility with the modified ethylene propylene diene monomer (EPDM) matrix was poor. Even with the assistance of a composite dispersant and staged mixing, complete deagglomeration and uniform dispersion could not be achieved, and some nano tungsten powder formed aggregates. These undispersed nano tungsten powder aggregates led to uneven distribution of shielding elements inside the material, directly affecting the uniformity of the radiation shielding performance lead equivalent. In Comparative Example 2, during the preparation of the radiation shielding powder, the nano tungsten powder was not pretreated with dilute nitric acid for acidification, lacking the active groups introduced by acidification on the surface, which affected the efficiency of silanization modification. The surface properties of this insufficiently modified nano tungsten powder were not improved enough, reducing its compatibility with the modified EPDM matrix. Even with staged addition and a composite dispersant, it was still difficult to disperse uniformly to the maximum extent, resulting in a decrease in the uniformity of the radiation shielding performance lead equivalent. In Comparative Example 3, when preparing the suspension of acidified pretreated nano tungsten powder during the preparation of the radiation shielding powder, the pH was not adjusted, and the pH of the suspension was not adjusted to the optimal value during the silanization modification process, affecting the hydrolysis of silane and the reaction efficiency with the surface of the acidified pretreated nano tungsten powder. The surface of this nano tungsten powder modified under non-optimal conditions did not obtain the best performance, reducing its dispersibility and resulting in a decrease in the uniformity of the radiation shielding performance lead equivalent.

[0081] These comparisons jointly reveal the importance of the surface pretreatment of nano tungsten powder for material properties. Comparative Example 1 demonstrated the worst dispersion and uniformity caused by no treatment at all. Comparative Example 2 and Comparative Example 3, by removing or interfering with the key steps of the surface treatment of nano tungsten powder, showed that these steps are indispensable for ensuring the effective grafting of silane coupling agents, fully improving the surface properties of nano tungsten powder, and thus achieving subsequent uniform dispersion. These comparisons jointly prove that the acidification pretreatment of nano tungsten powder and the pH control during the silanization modification process, as well as their coordination with subsequent processing technologies, are the basis for ensuring the uniform dispersion of nano tungsten powder and thus guaranteeing the uniformity of the radiation shielding performance.

[0082] Test Example 2

[0083] Test objects: Example 1, Examples 3 - 4, and Comparative Examples 4 - 7, Comparative Example 15.

[0084] Test method: The test was carried out with reference to GB28881 - 2023 "Hand Protection - Chemical and Microbial Protection Gloves". The final test results are shown in Table 2.

[0085] Table 2 Test Results of Anti - Penetration Performance

[0086]

[0087] Modified EPDM rubber enhances its compatibility and reactivity with fillers; it cooperates with the peroxide system and the vulcanizing agent to build a strong cross-linking network and interface that firmly anchors the filler in the primary and secondary vulcanization processes; this linkage between the matrix and the vulcanization system ensures efficient stress transmission and chemical penetration hindrance, enhancing the mechanical puncture resistance and anti-penetration properties of the gloves.

[0088] Comparative Example 4: The unmodified EPDM rubber lacks functional groups such as epoxy groups and methacrylate double bonds, and its compatibility and chemical reactivity with fillers are insufficient; during peroxide vulcanization, it is difficult for the unmodified rubber to form a strong covalent connection interface with the surface active groups of the filler and the silane coupling agent, and the filler is not firmly anchored; the interface bonding is weak, and chemical reagents are easy to penetrate along the microscopic gaps, and it is impossible to form a dense chemical permeation barrier, which reduces its resistance to chemical permeation. Comparative Example 5: The screw speed of the modified EPDM rubber preparation is 150rpm, the grafting rate is lower than the optimal, and the number of functional groups introduced into the insufficiently modified rubber is insufficient; the compatibility and reactivity of the insufficiently modified rubber with the filler are reduced, and the number of chemical connections formed at the filler-rubber interface is insufficient and the strength is insufficient; the interface bonding is not strong, and chemical reagents are also easy to penetrate along the weak interface, and the resistance to chemical permeation is reduced. Comparative Example 6 lacks the vulcanization aid triallyl isocyanurate, the cross-linking efficiency of the peroxide vulcanization system is insufficient, and the cross-linking network is imperfect; the lack of the vulcanizing aid affects the covalent connection between the double-bond component and the rubber network, weakening the chemical anchoring strength of the filler; the imperfect network weakens the interface bonding, and the chemical reagents are more likely to penetrate, making its chemical permeability resistance worse. Comparative Example 7 removes the secondary vulcanization, and the cross-linking groups that are not fully reacted in the primary vulcanization fail to react further, and the cross-linking network is not fully and completely cured; this incompletely mature and stable network interface is structurally changeable under the action of chemical media, reducing the anti-permeability performance. In Comparative Example 15, because the plasticizing temperature is low and the initiator is lacking, glycidyl methacrylate is difficult to effectively graft onto the main chain of EPDM rubber, resulting in the number of functional groups such as epoxy groups introduced into the rubber being far from sufficient; this matrix has poor compatibility with the filler, and during the vulcanization stage, the rubber and filler are weakly bonded, and the chemical reagents are easy to penetrate along the microscopic gaps, and cannot form a dense chemical permeation barrier, which reduces its chemical permeability resistance.

[0089] These comparisons jointly demonstrate the criticality of the modified EPDM rubber matrix and the specific peroxide vulcanization system and its primary and secondary vulcanization process to improve the chemical penetration resistance. Comparative Examples 4 and 15 show that the chemical structure of the rubber matrix itself is important. Comparative Example 5 suggests that even if modified, the process parameters also affect the effect. Comparative Examples 6 and 7 show that these links are indispensable for forming a perfect cross-linked network, curing interface bonding, and improving the long-term anti-penetration stability of the material from the perspective of vulcanization system components and process steps. These comparisons prove that the synergy of the entire system from matrix modification to final vulcanization molding is the basis for building a dense chemical penetration barrier.

[0090] Test Example 3

[0091] Test objects: Example 1, Example 4, Examples 6 - 7, Comparative Examples 8 - 10, and Comparative Example 16.

[0092] Test method: The test was carried out with reference to Standard GB 24541 - 2022. The final test results are shown in Table 3.

[0093] Table 3 Test Results of Mechanical Hazard Protection Performance

[0094]

[0095] The silane - modified silica and acid - treated aramid pulp cooperate to construct a stronger multi - scale filler network through surface interaction and chemical bonding; this composite reinforcing agent chemically bonds with the modified rubber matrix and is firmly anchored in the rubber network; this synergy between fillers and the linkage between fillers and the matrix significantly improves the mechanical properties of the material and the anti - permeation performance achieved through the barrier network and the reinforcing interface.

[0096] Level 1 in the standard is the minimum standard, and the comparative examples cannot meet the Level 1 standard. Comparative example 8 lacks a composite reinforcing agent composed of surface-modified precipitated silica silicified aramid pulp. The material cannot construct a high-modulus silica skeleton and high-strength aramid fiber connections to form a more robust multi-scale composite filler network; it lacks a strong filler network skeleton and a chemical bonding interface with its modified rubber matrix, resulting in a reduced stress transfer efficiency, insufficient overall strength and toughness of the material, difficulty in resisting puncture by sharp objects and preventing crack propagation, and reduced puncture and tear resistance. Comparative example 9 lacks silane-modified precipitated silica. The filler network formed by acid-treated aramid pulp lacks the support of stiffness and modulus and cannot construct a more robust multi-scale network bridged by a silica skeleton and aramid fibers; although aramid fibers provide strength and toughness, the overall filler network structure is incomplete, the chemical bonding points with the modified rubber matrix are reduced, the interfacial bonding strength is impaired, and the stress transfer efficiency is reduced; the overall reinforcement effect is weakened, the strength and stiffness of resisting puncture are insufficient, the ability to resist crack propagation is weakened, and the puncture and tear resistance is poor. Comparative example 10 lacks acid-treated aramid pulp. The network of silane-modified precipitated silica particles lacks the bridging connection of high-strength fibers, and the toughness and continuity of the filler network skeleton are insufficient; it lacks the stress dispersion and crack arrest effect of high-strength fibers, and the filler network is prone to fracture at stress concentration points; the chemical bonding points with the modified rubber matrix are reduced, the interfacial bonding strength is impaired, and the stress cannot be transferred to the high-strength fiber unit, resulting in a reduction in the overall toughness and crack propagation resistance of the material and a reduction in puncture and tear resistance. In comparative example 16, the cohesion between unmodified precipitated silica particles is strong, and its compatibility with the modified ethylene propylene diene monomer rubber is poor; the surface of unmodified aramid pulp is relatively inert, and its affinity with the rubber matrix and precipitated silica is insufficient; these two fillers lack an effective synergistic effect, making it difficult to construct a robust multi-scale composite filler network, resulting in a reduced stress transfer efficiency, difficulty in effectively resisting penetration by sharp objects and preventing crack propagation, and a reduction in its puncture resistance and tear resistance.

[0097] These comparisons together demonstrate the crucial role of the composite reinforcing agent composed of surface-modified precipitated silica and acid-treated aramid pulp and the synergistic effect of its internal components in improving the mechanical properties of the material. Comparative example 8 shows that the overall composite reinforcing agent is necessary to significantly improve strength and toughness. Comparative examples 9 and 10, by removing a single component of the composite reinforcing agent, respectively show that precipitated silica provides a stiffness skeleton and aramid pulp provides fiber bridging toughness and crack resistance. Comparative example 16 illustrates the importance of the modification of the internal components of the composite reinforcing agent and their synergistic effect. These comparative examples prove that there is a synergistic reinforcement effect between precipitated silica and aramid pulp, jointly improving the puncture and tear resistance of rubber gloves.

[0098] Test example 4

[0099] Test objects: Example 1, Example 6, Examples 8 - 9, and Comparative examples 11 - 14.

[0100] Test method: The test method refers to Test Examples 1-3. The final test results are shown in Tables 4-6.

[0101] Table 4 Test Results of Radiation Protection Performance of Example 1, Example 6, Examples 8-9 and Comparative Examples 11-14

[0102]

[0103] Table 5 Test Results of Anti-Permeation Performance of Example 1, Example 6, Examples 8-9 and Comparative Examples 11-14

[0104]

[0105] Table 6 Test Results of Mechanical Hazard Protection Performance of Example 1, Example 6, Examples 8-9 and Comparative Examples 11-14

[0106]

[0107] Processing aids such as glycerol monostearate, zinc stearate and paraffin oil synergistically modify the rubber matrix, greatly improving the processability of the rubber compound in the multi-stage mixing and open milling process and promoting the uniform dispersion of fillers; the filtration process further ensures the purity and uniformity of the mixed rubber; the linkage between processing optimization and filtration ensures a highly uniform dispersion of fillers and a defect-free matrix, improving the radiation protection uniformity, anti-permeation property and mechanical properties.

[0108] Comparative Example 11: When the super-high filling radiation shielding powder dispersant was added all at once during internal mixing, the viscosity of the rubber compound increased instantaneously, making it difficult for processing aids to effectively wet and coat. It was difficult to promote the deagglomeration and uniform dispersion of fillers under the high shear of internal mixing; the impurities of undispersed agglomerates increased, and the purity and uniformity of the mixed rubber became worse; the uneven dispersion of fillers directly affected the radiation protection uniformity, the interfacial defects of filler agglomerates increased, the anti-permeability decreased, the stress transfer efficiency of the unevenly dispersed filler network was low, and the mechanical properties decreased. Comparative Example 12: After internal mixing, the viscosity of the basic masterbatch was high, and the shear force during the open mixing stage was relatively low; when a large amount of radiation shielding powder dispersant was added all at once at this stage, it was difficult for processing aids to quickly and effectively wet and coat, and it was difficult to break up the filler agglomerates in the high-viscosity system and uniformly disperse them under the low shear of the open mill; the uneven dispersion of fillers directly affected the radiation protection uniformity, the interfacial defects of filler agglomerates increased, the anti-permeability decreased, the stress transfer efficiency of the unevenly dispersed filler network was low, and the mechanical properties decreased. Comparative Example 13: Due to the lack of the synergistic effect of key composite dispersants and lubricants such as zinc stearate and monoglyceride stearate, the wetting and coating ability of the modified ethylene propylene diene monomer rubber for super-high filling fillers decreased, and it was difficult to overcome the frictional cohesion trend between filler particles; even if multi-stage mixing and filtration were carried out, it was impossible to maximize the promotion of filler deagglomeration and uniform dispersion; the uneven dispersion of fillers directly affected the radiation protection uniformity, the interfacial defects of filler agglomerates increased, the anti-permeability decreased, the stress transfer efficiency of the unevenly dispersed filler network was low, and the mechanical properties decreased. Comparative Example 14: When the filtration process was removed, trace impurities and a few stubborn large agglomerates would be mixed in during mixing, and the purity and uniformity of the mixed rubber decreased; these impurities and agglomerates formed defects in the vulcanized product, destroying the continuity and uniformity of the filler network and weakening the interfacial bonding between the filler and the rubber; these defect points were stress concentration sources and fast channels for chemical reagent penetration; the uniformity of filler distribution was damaged, directly affecting the radiation protection uniformity, the internal defects of the material increased, the anti-permeability decreased, and the expansion of stress concentration defects led to a decrease in mechanical properties.

[0109] These comparisons jointly reveal the synergistic effect of processing aids, multi-stage mixing process, and filtration process in solving the processing problems of super-high filling and improving the quality of mixed rubber. Comparative Example 13 shows that the key to realizing the preliminary wetting of fillers and reducing viscosity is the composite processing aids. Comparative Examples 11 and 12 show that by changing the way of adding fillers, even with dispersants, adding super-high filling amount of fillers in stages and using the characteristics of internal mixing and open mixing for fine mixing is crucial for maximizing uniform dispersion. Comparative Example 14 shows that even with fine mixing and dispersant assistance, the filtration process, as the last step of physically removing impurities and large agglomerates, is indispensable for ensuring the final purity and uniformity of the mixed rubber. These comparisons jointly prove that the synergy of processing aids, fine mixing process, and filtration process is the basis for obtaining high-quality and high-filling mixed rubber, and further ensures the stable and excellent performance of the final product.

[0110] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A preparation method of a tungsten-containing lead-free radiation-proof rubber glove, characterized in that: The specific preparation steps are as follows: After the modified ethylene propylene diene monomer (EPDM) rubber is plastisized, an activator and an antioxidant are added for the first stage of internal mixing, then carbon black, a composite reinforcing agent, a radiation shielding powder, and a dispersant are added for the second stage of internal mixing, and finally paraffin oil is added for the third stage of internal mixing to obtain a crude mixed rubber; The crude mixed rubber, the radiation shielding powder, the dispersant, a vulcanizing agent, and a vulcanization aid are mixed and kneaded on an open mill to obtain a rubber sheet; the rubber sheet is filtered, injection molded, two-stage vulcanized, cleaned, and dried to obtain the tungsten-containing lead-free radiation shielding rubber gloves; The preparation method of the modified EPDM rubber is as follows: by weight, 95-105 parts of EPDM rubber are fed into a twin-screw extruder; simultaneously, a mixture of 5-7 parts of glycidyl methacrylate and 2,5-dimethyl-2,5-di-tert-butylperoxyhexane is injected; the screw speed is 250-300 rpm; the molten modified EPDM rubber is extruded, cooled, pelletized, and dried to obtain the modified EPDM rubber; The preparation method of the radiation shielding powder is as follows: nano tungsten powder is dispersed in a dilute nitric acid solution, stirred, centrifuged, washed, and dried to obtain acid-treated nano tungsten powder; The acid-treated nano tungsten powder is dispersed in a mixed solution composed of anhydrous ethanol and deionized water; after ultrasonic dispersion, the pH value is adjusted to 4.5-5.5 with a dilute hydrochloric acid solution to obtain a suspension; γ-methacryloxypropyltrimethoxysilane is added to the suspension and stirred for reaction for 2-2.5 hours; after the reaction, it is centrifuged, washed, and dried to obtain the radiation shielding powder; The preparation method of the composite reinforcing agent is as follows: precipitated silica reacts with γ-methacryloxypropyltrimethoxysilane to prepare modified precipitated silica; aramid pulp is acidified with dilute nitric acid to prepare modified aramid pulp; the modified precipitated silica and the modified aramid pulp are mixed in a weight ratio of 9-11:1 to obtain the composite reinforcing agent; The preparation method of the rubber sheet is as follows: the crude mixed rubber is transferred to an open mill with a roll temperature of 30°C - 40°C; the radiation shielding powder and the dispersant are added in portions on the open mill, and then 8-12 parts of the vulcanizing agent and 3-4 parts of the vulcanization aid are added; Continue to repeatedly cut, turn, and calender the rubber to obtain the rubber sheet; The two-stage vulcanization process is as follows: the rubber sheet is filtered to obtain a rubber strip, the rubber strip is preheated and molded and then subjected to primary vulcanization, the set temperature is 155-165°C, and it is maintained for 8-10 min; after the primary vulcanized gloves are cooled, they are subjected to secondary vulcanization, the secondary vulcanization temperature is 130-140°C, and the secondary vulcanization time is 20-30 min.

2. The preparation method of a tungsten-containing lead-free radiation-proof rubber glove according to claim 1, characterized in that: By weight, the addition amount of γ-methacryloxypropyltrimethoxysilane is 4-6% of the acid-treated nano tungsten powder.

3. The preparation method of a tungsten-containing lead-free radiation-proof rubber glove according to claim 1, characterized in that: The preparation method of the crude mixed rubber is as follows: The temperature of the plastisization is 70-80°C, and the time of the plastisization is 8-10 min; The temperature of the first stage of internal mixing is 80-90°C, and the time of the first stage of internal mixing is 6-8 min; The temperature of the second stage of internal mixing is 80-90°C, and the time of the second stage of internal mixing is 10-15 min; The temperature of the third stage of internal mixing is 90 - 100 °C, and the time of the third stage of internal mixing is 5 - 9 min.

4. A tungsten-containing lead-free radiation-proof rubber glove prepared by the preparation method according to claim 1, characterized in that: The raw materials for preparing the tungsten-containing lead-free radiation-proof rubber gloves include: modified ethylene propylene diene monomer rubber, activator, anti-aging agent, carbon black, composite reinforcing agent, radiation shielding powder, dispersant, paraffin oil, vulcanizing agent, vulcanization aid; The activator is a mixture of zinc oxide and stearic acid; the anti-aging agent is antioxidant 1010; the carbon black is carbon black N660; the dispersant is monoglyceryl stearate; the vulcanizing agent is dicumyl peroxide; the vulcanization aid is triallyl isocyanurate.

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