Tungsten-containing lead-free anti-radiation rubber glove and preparation method thereof

Abstract

The invention relates to the technical field of high polymer materials, in particular to tungsten-containing lead-free anti-radiation rubber gloves and a preparation method thereof. The anti-radiation fabric overcomes the defects of poor anti-radiation capability and poor anti-permeation performance. The preparation method comprises the following steps: plastifying modified ethylene propylene diene monomer rubber, adding an active agent and an anti-aging agent, carrying out first-time internal mixing, adding carbon black, a composite reinforcing agent, radiation shielding powder and a dispersant, carrying out second-time internal mixing, and finally adding paraffin oil, and carrying out third-time internal mixing to obtain a crude rubber compound; mixing the crude rubber compound, radiation shielding powder, a dispersing agent, a vulcanizing agent and a vulcanizing aid, and performing open milling to obtain a rubber sheet; and the tungsten-containing lead-free anti-radiation rubber gloves are obtained after the rubber sheets are subjected to standing, filtering, injection molding, two-stage vulcanization, cleaning and drying. The tungsten-containing lead-free anti-radiation rubber glove prepared by the invention has strong anti-radiation performance and strong anti-permeation performance, and is suitable for protection in a complex radiation environment.

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 ways, 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 gradually becomes 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 and corrode the internal protection materials, 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 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; the tungsten-containing lead-free radiation protection rubber glove is obtained after the rubber sheet is parked, filtered, injection molded, second-stage vulcanized, cleaned and dried. 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: 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: Prepare radiation shielding powder from nano tungsten powder and γ-methacryloxypropyltrimethoxysilane as raw materials; React ethylene propylene diene monomer rubber with glycidyl methacrylate to prepare modified ethylene propylene diene monomer rubber; Prepare a composite reinforcing agent from precipitated silica and aramid pulp as raw materials; After the modified ethylene propylene diene monomer rubber is plastically refined, 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; 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, second-stage vulcanize, wash, and dry the rubber sheet to obtain a tungsten-containing lead-free radiation shielding rubber glove.

[0008] Preferably, the preparation method of the modified ethylene propylene diene monomer rubber is: by weight, feed 95-105 parts of ethylene propylene diene monomer rubber into a twin-screw extruder; synchronously 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.

[0009] Preferably, the preparation method of the radiation shielding powder is: 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.

[0010] Preferably, by weight, the addition amount of γ-methacryloxypropyltrimethoxysilane is 4-6% of the acidified pretreated nano tungsten powder.

[0011] Preferably, the preparation method of the composite reinforcing agent is: react precipitated silica with γ-methacryloxypropyltrimethoxysilane to prepare modified precipitated silica; prepare modified aramid pulp 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.

[0012] Preferably, the method for preparing the crude mixed rubber is as follows: The temperature of plasticizing is 70 - 80 °C, and the time of plasticizing 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.

[0013] Preferably, the method for preparing the rubber sheet is as follows: By weight, transfer the crude mixed rubber to an open mill with a roller temperature of 30 °C - 40 °C; add the radiation shielding powder and the dispersant in portions on the open mill, then add 8 - 12 parts of the vulcanizing agent and 3 - 4 parts of the vulcanization aid; continue to repeatedly cut, turn, and calender the rubber to obtain the rubber sheet.

[0014] Preferably, the two - stage vulcanization process is as follows: After filtering the rubber sheet to obtain a rubber strip, preheat and form the rubber strip and then conduct the first - stage vulcanization, set the temperature at 155 - 165 °C, the pressure at 30 MPa, and maintain for 8 - 10 min; after cooling the gloves after the first - stage vulcanization, conduct the second - stage vulcanization, the temperature of the second - stage vulcanization is 130 - 140 °C, and the time of the second - stage vulcanization is 30 - 40 min.

[0015] On the other hand, the present invention provides a tungsten - containing lead - free radiation - shielding rubber glove. The raw materials for preparing the tungsten - containing lead - free radiation - shielding 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; 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.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. In the present invention, the modified nano - tungsten powder reduces the surface energy and introduces reactive functional groups. With the wetting and lubricating effects of dispersants such as zinc stearate and monoglyceryl stearate, through fine mixing of 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 rubber matrix to construct a strong covalent interface during vulcanization, realizing the firm anchoring of nano - tungsten powder. The excellent dispersion uniformity ensures uniform and reliable radiation - shielding performance, and the strong interfacial bonding improves the mechanical anti - penetration performance.

[0017] 2. In the present invention, the modified rubber improves the compatibility and reactivity with the modified filler, forms a firm interface with the active groups and silane on the filler surface through multiple covalent bonds during the vulcanization stage, and constructs a strong integrated cross-linked network. The primary and secondary vulcanization further cures and perfects this network. The strong filler-rubber interfacial bonding can efficiently transfer stress, significantly improve the mechanical properties and enhance puncture resistance; at the same time, it constitutes a dense chemical penetration barrier, greatly improving the anti-permeability performance.

[0018] 3. In the present invention, the silane-modified silica introduces reactive functional groups, and the acidified aramid pulp introduces polar reactive groups. Through 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 chemically bonds with the modified rubber matrix and is firmly anchored in the rubber network. This synergistic network significantly improves the puncture and tear resistance of the material.

[0019] 4. In the present invention, the processing aids reduce viscosity, improve wetting and lubrication, and synergistically promote the uniform dispersion of the filler during multi-stage mixing; the filtration process removes impurities and large agglomerates, improves the purity and uniformity of the mixed rubber, and ensures 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, improving anti-permeability; 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

[0020] 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

[0021] 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 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.

[0022] Please refer to Figure 1 , the present invention provides a tungsten-containing lead-free radiation protection rubber glove and its preparation method, and the technical solutions are as follows: Example 1 Preparation of Modified Ethylene Propylene Diene Monomer Rubber 95 parts of ethylene propylene diene monomer rubber are continuously fed into the main feeding port of a twin-screw extruder; simultaneously, 5 parts of glycidyl methacrylate and 0.5 part of a mixture of 2,5-dimethyl-2,5-di-tert-butylperoxyhexane are injected into the third temperature zone of the barrel through a liquid injection pump; the temperatures of each temperature zone of the twin-screw extruder barrel are set 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 vacuum exhaust is carried out in the seventh temperature zone; the molten modified ethylene propylene diene monomer 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; glycidyl methacryloxy grafted modified ethylene propylene diene monomer rubber is obtained.

[0023] Preparation of radiation shielding powder 400 parts of nano tungsten powder with a particle size of 30 - 50 nm are dispersed in 2000 parts of a 5% mass fraction dilute nitric acid solution; after continuously stirring at room temperature for 30 min, centrifugal separation and washing are carried out until the pH value of the washing liquid is neutral, and the centrifugal precipitate is dried in a vacuum oven at 80°C for 12 hours to obtain acidified pretreated nano tungsten powder; 400 parts of acidified pretreated nano tungsten powder are dispersed in a mixed solution composed of 2000 parts of absolute ethanol and 20 parts of deionized water, and ultrasonic dispersion is carried out for 20 min; 1% mass fraction dilute hydrochloric acid is slowly added to adjust the pH value of the system to 4.5; 4% by weight of γ-methacryloxypropyltrimethoxysilane based on the weight of the acidified pretreated nano tungsten powder is added to the suspension; the system is heated to 60°C and continuously stirred and reacted for 2 hours; after the reaction, centrifugal separation and washing are carried out until the pH value of the washing liquid is neutral, and it is dried in a vacuum oven at 80°C for 12 hours; radiation shielding powder is obtained.

[0024] Preparation of composite reinforcing agent 40 parts of precipitated silica are dispersed in a mixed solution composed of 400 parts of absolute ethanol and 0.5 part of deionized water, and ultrasonic dispersion is carried out for 30 minutes to form a uniform suspension. Under continuous stirring, an absolute ethanol solution of 3 parts of γ-methacryloxypropyltrimethoxysilane is added to the suspension. Stirring reaction is carried out at 60°C for 2 hours, after the reaction, centrifugal separation and washing are carried out, and after repeating 2 times, the centrifuged solid is dried in a vacuum oven at 80°C for 12 hours to obtain modified precipitated silica.

[0025] 100 parts of aramid pulp are ultrasonically dispersed in 2000 parts of a 10% mass fraction dilute nitric acid solution to form a suspension system. Stirring reaction is carried out at 60°C for 2 hours, after the reaction, centrifugal separation and washing are carried out, and after repeating 2 times, the centrifuged solid is dried in a vacuum oven at 80°C for 12 hours to obtain modified aramid pulp.

[0026] The modified precipitated silica and the modified aramid pulp are mixed in a weight ratio of 9:1 to obtain 30 parts of composite reinforcing agent.

[0027] Plasticate 100 parts of modified ethylene propylene diene monomer rubber in a Banbury mixer at a temperature of 70 °C for 8 minutes; For the first stage of mixing of the plasticated rubber compound in a Banbury mixer, at a temperature of 80 °C, add 5 parts of zinc oxide, 1 part of stearic acid, 1 part of antioxidant 1010, and 3 parts of calcium oxide, for 6 minutes; Transfer the rubber compound after the first stage of Banbury mixing to the second stage of Banbury mixing at a temperature of 80 °C, add 30 parts of carbon black N660, 30 parts of composite reinforcing agent, 150 parts of surface-modified nano tungsten powder, and 2.5 parts of monoglyceryl stearate, for 10 minutes; transfer the rubber compound after the second stage of Banbury mixing to the third stage of Banbury mixing at a temperature of 90 °C, add 40 parts of paraffin oil, for 5 minutes, to obtain a roughly mixed rubber compound.

[0028] 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 dispersant monoglyceryl stearate in 5 portions on the open mill, with a 2-minute interval between each addition; perform dispersion by repeatedly cutting, turning, and calendering the rubber; after adding the radiation shielding powder and the dispersant 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 process of mixing and adding materials on the open mill lasts for 35 minutes; finally, calender into a film with a thickness of 8 mm - 10 mm.

[0029] Thermally condition 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 is ≤ 190 mm and the length is ≤ 800 mm. Push the rubber roll into a plunger-type precision preforming machine equipped with a 150# filter screen to extrude a rubber strip. The cross-sectional size of the rubber strip is 50 × 20 mm, and let it cool naturally to room temperature.

[0030] Preheat the rubber strip to 70 °C and then inject it into the mold cavity for injection molding; perform the first vulcanization, set the temperature at 155 °C, the pressure at 30 MPa, and hold for 10 minutes; cool the gloves after the first vulcanization; perform the second vulcanization on the gloves that have passed 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 minutes. Finally, wash the gloves after the second vulcanization with clean water, and then dry them at 70 °C for 40 minutes to obtain the tungsten-containing lead-free radiation shielding rubber gloves.

[0031] The difference between Example 2 and Example 1 is that in the preparation of the radiation shielding powder, the mass fraction of the dilute nitric acid solution is 5.5%; stir and react for 2.3 hours; the addition amount of γ-methacryloxypropyltrimethoxysilane is 5% of the mass of the acidified pretreated nano tungsten powder.

[0032] Example 3 is different from Example 1 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.

[0033] Example 4 is different from Example 2 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 rotation speed is 275 rpm; in the preparation of the rubber sheet, 9.5 parts of vulcanizing agent are added; 3.5 parts of vulcanization aids are added; in the two-stage vulcanization, the primary vulcanization temperature is maintained at 160 °C for 9 min; the secondary vulcanization temperature is 135 °C and the secondary vulcanization time is 25 min.

[0034] Example 5 is different from Example 2 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 rotation speed is 300 rpm; in the preparation of the rubber sheet, 12 parts of vulcanizing agent are added; 4 parts of vulcanization aids are added; in the two-stage vulcanization, the primary vulcanization temperature is maintained at 165 °C for 8 min; the secondary vulcanization temperature is 140 °C and the secondary vulcanization time is 20 min.

[0035] Example 6 is different from Example 4 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.

[0036] Example 7 is different from Example 4 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.

[0037] 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 min; the first mixing temperature is 85 °C for 7 min; the second mixing temperature is 85 °C for 12.5 min; the third mixing temperature is 95 °C for 7 min; in the preparation of the rubber sheet, the roller temperature is 35 °C.

[0038] 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 min; the first mixing temperature is 90 °C for 8 min; the second mixing temperature is 90 °C for 15 min; the third mixing temperature is 100 °C for 9 min; in the preparation of the rubber sheet, the roller temperature is 40 °C.

[0039] Comparative Example 1 is different from Example 1 only in that: the radiation shielding powder uses nano tungsten powder without any treatment.

[0040] The difference between Comparative Example 2 and Example 1 is only that: during the preparation of the radiation shielding powder, the nano tungsten powder is not pretreated by acidification with dilute nitric acid.

[0041] The difference between Comparative Example 3 and Example 1 is only that: during the preparation of the radiation shielding powder, the pH is not adjusted when preparing the suspension of the acidified pretreated nano tungsten powder.

[0042] The difference between Comparative Example 4 and Example 1 is only that: the ethylene propylene diene monomer rubber is not subjected to modification treatment.

[0043] The difference between Comparative Example 5 and Example 1 is only that: during the preparation of the modified ethylene propylene diene monomer rubber, the screw speed is 150 rpm.

[0044] 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.

[0045] The difference between Comparative Example 7 and Example 1 is only that: one vulcanization is carried out to remove the second vulcanization step.

[0046] The difference between Comparative Example 8 and Example 1 is only that: the composite reinforcing agent is not added.

[0047] The difference between Comparative Example 9 and Example 1 is only that: the modified precipitated silica in the composite reinforcing agent is removed.

[0048] The difference between Comparative Example 10 and Example 1 is only that: the modified aramid pulp in the composite reinforcing agent is removed.

[0049] 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.

[0050] The difference between Comparative Example 12 and Example 1 is only that: in the open mill stage, the radiation shielding powder and the dispersant are added at one time.

[0051] The difference between Comparative Example 13 and Example 1 is only that: the dispersant is not added in both the second stage of internal mixing and the open mill stage.

[0052] The difference between Comparative Example 14 and Example 1 is only that: the filtration process is removed.

[0053] The difference between Comparative Example 15 and Example 1 is only that: the ethylene propylene diene monomer rubber is not subjected to modification treatment, and in the plasticating step, the ethylene propylene diene monomer rubber and glycidyl methacrylate are added to the plasticator together.

[0054] 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.

[0055] Test Example 1 Test objects: rubber gloves prepared in Examples 1-3 and Comparative Examples 1-3.

[0056] Test method: Tested in accordance with GBZ / T147-2002 standard. The final test results are shown in Table 1.

[0057] Table 1 Radiation protection performance test results 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.

[0058] Comparative Example 1 uses nano tungsten powder that has not been treated in any way. Its high surface energy and cohesive force make it difficult to disperse evenly, and its compatibility with the modified EPDM rubber matrix is ​​poor; even with the assistance of composite dispersants and staged mixing, it is impossible to achieve complete deagglomeration and uniform dispersion, and some nano tungsten powders form aggregates; these undispersed nano tungsten powder aggregates lead to uneven distribution of shielding elements inside the material, which directly affects the uniformity of lead equivalent in radiation protection performance. In the preparation of radiation shielding powder in Comparative Example 2, nano tungsten powder is not acidified with dilute nitric acid, and the surface lacks active groups introduced by acidification, which affects the efficiency of silanization modification; the surface properties of this inadequately modified nano tungsten powder are not improved enough, which reduces its compatibility with the modified EPDM rubber matrix. Even with staged addition and composite dispersants, it is still difficult to disperse evenly to the maximum extent, resulting in a decrease in the uniformity of lead equivalent in radiation protection performance. In the preparation of radiation shielding powder in Comparative Example 3, the pH is not adjusted when preparing the suspension of acid pretreated nano-tungsten powder, and the pH of the suspension is not adjusted to the optimal level during the silanization modification process, which affects the hydrolysis of silane and the reaction efficiency with the surface of the acid pretreated nano-tungsten powder; the surface of the nano-tungsten powder that is not modified under the optimal conditions fails to obtain the best performance, reduces its dispersion ability, and causes a decrease in the uniformity of the lead equivalent of the radiation protection performance.

[0059] These comparisons together reveal the importance of surface pretreatment of nano tungsten powder on material properties. Comparative Example 1 shows the worst dispersion and uniformity brought about 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, show that these steps are indispensable for ensuring the effective grafting of silane coupling agent, fully improving the surface properties of nano tungsten powder, and thus achieving subsequent uniform dispersion. These comparisons together prove that the acidification pretreatment and pH control in the silanization modification process of nano tungsten powder, as well as their synergy with subsequent processing technologies, are the basis for ensuring the uniform dispersion of nano tungsten powder and thus guaranteeing the uniformity of radiation protection performance.

[0060] Test Example 2 Test objects: Example 1, Examples 3 - 4, and Comparative Examples 4 - 7, Comparative Example 15.

[0061] Test method: Refer to GB28881 - 2023 "Hand Protection - Chemical and Microbial Protection Gloves" for testing. The final test results are shown in Table 2.

[0062] Table 2 Test Results of Anti - Penetration Performance The modified ethylene - propylene - diene monomer (EPDM) enhances the compatibility and reactivity with fillers; in cooperation with the peroxide system and the co - vulcanizing agent, a strong cross - linked network and interface that firmly anchor the fillers are constructed in the primary and secondary vulcanization processes; this linkage between the matrix and the vulcanization system ensures efficient stress transfer and chemical penetration hindrance, enhancing the mechanical puncture - resistance and anti - penetration performance of the gloves.

[0063] In Comparative Example 4, the unmodified ethylene propylene diene monomer (EPDM) rubber lacks functional groups such as epoxy groups and methacrylate double bonds, resulting in insufficient compatibility and chemical reaction ability with fillers. 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 interfacial bonding is weak, and chemical reagents are easily permeated along the microscopic gaps, unable to form a dense chemical permeation barrier, thus reducing its chemical resistance to permeation. In Comparative Example 5, the screw speed of the modified EPDM rubber preparation is 150 rpm, and the grafting rate is lower than the optimum, with insufficient introduction of functional groups in the insufficiently modified rubber. The compatibility and reactivity of the insufficiently modified rubber with the filler are reduced, resulting in insufficient quantity and strength of the chemical connections at the filler-rubber interface. The interfacial bonding is not firm, and chemical reagents are also easily permeated along the weak interface, reducing the chemical resistance to permeation. In Comparative Example 6, the vulcanization aid triallyl isocyanurate is lacking, the crosslinking efficiency of the peroxide vulcanization system is insufficient, and the crosslinking network is imperfect. The absence of the co-vulcanizing agent affects the covalent connection between the double bond-containing components and the rubber network, weakening the chemical anchoring strength of the filler. The imperfect network weakens the interfacial bonding, and chemical reagents are more likely to permeate, making its chemical resistance to permeation worse. In Comparative Example 7, the secondary vulcanization is removed, and the unreacted crosslinking groups in the primary vulcanization fail to react further, and the crosslinking network is not fully perfected and cured. This immature and unstable network interface is prone to structural changes under the action of chemical media, reducing the anti-permeation performance. In Comparative Example 15, due to the low plasticization temperature and the lack of initiator, glycidyl methacrylate is difficult to effectively graft onto the main chain of EPDM rubber, resulting in far insufficient quantity of functional groups such as epoxy groups introduced into the rubber. The compatibility between this matrix and the filler is poor. During the vulcanization stage, the bonding between the rubber and the filler is weak, and chemical reagents are easily permeated along the microscopic gaps, unable to form a dense chemical permeation barrier, thus reducing its chemical resistance to permeation.

[0064] These comparisons together demonstrate the key role of the modified EPDM rubber matrix in synergizing with this specific peroxide vulcanization system and its primary and secondary vulcanization processes for enhancing the chemical resistance to permeation. Comparative Example 4 and Comparative Example 15 show the importance of the chemical structure of the rubber matrix itself. Comparative Example 5 indicates that even with modification, process parameters also affect the effect. Comparative Example 6 and Comparative Example 7 show from the perspectives of the components of the vulcanization system and the process steps that these links are indispensable for forming a perfect crosslinking network, curing the interfacial bonding, and enhancing the long-term anti-permeation stability of the material. These comparisons prove that the synergy of the entire system from matrix modification to final vulcanization molding is the basis for constructing a dense chemical permeation barrier.

[0065] Test Example 3 Test objects: Example 1, Example 4, Example 6 - 7, and Comparative Example 8 - 10, Comparative Example 16.

[0066] Test method: The test is carried out with reference to Standard GB 24541-2022. The final test results are shown in Table 3.

[0067] Table 3 Test Results Table of Mechanical Hazard Protection Performance 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-permeability performance achieved through the barrier network and the reinforcing interface.

[0068] Level 1 in the standard is the minimum standard and the comparative examples cannot reach the Level 1 standard. Comparative example 8 lacks a composite reinforcing agent composed of surface-modified precipitated silica acid-treated aramid pulp, and the material cannot construct a stronger multi-scale composite filler network composed of a high-modulus silica skeleton and high-strength aramid fiber connections; lacking a strong filler network skeleton and its chemical bonding interface with the modified rubber matrix, the stress transfer efficiency is reduced, the overall strength and toughness of the material are insufficient, it is difficult to resist the puncture of sharp objects and prevent crack propagation, and the puncture resistance and tear resistance are reduced. Comparative example 9 lacks silane-modified precipitated silica, and the filler network formed by acid-treated aramid pulp lacks the support of stiffness modulus and cannot construct a stronger multi-scale network composed of a silica skeleton and aramid fiber bridging; although the aramid fiber provides strength and toughness, the overall network structure of the filler is incomplete, the chemical bonding points with the modified rubber matrix are reduced, the interfacial bonding strength is damaged, and the stress transfer efficiency is reduced; the overall reinforcement effect is weakened, the puncture resistance strength and stiffness are insufficient, the ability to resist crack propagation is weakened, and the puncture resistance and tear resistance become worse. Comparative example 10 lacks acid-treated aramid pulp, and the silane-modified precipitated silica particle network lacks the bridging connection of high-strength fibers, and the toughness and continuity of the filler network skeleton are insufficient; lacking the stress dispersion and crack arrest effect of high-strength fibers, the filler network is prone to fracture at the stress concentration point; the chemical bonding points with the modified rubber matrix are reduced, the interfacial bonding strength is damaged, 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 the puncture resistance and tear resistance. In comparative example 16, the cohesion between unmodified precipitated silica particles is strong, and the compatibility with the modified ethylene propylene diene monomer rubber is poor; the surface of the unmodified aramid pulp is relatively inert, and the affinity with the rubber matrix and precipitated silica is insufficient; these two fillers lack effective synergy and it is difficult to construct a strong multi-scale composite filler network, resulting in a reduction in stress transfer efficiency and it is difficult to effectively resist the penetration of sharp objects and prevent crack propagation, thus reducing its puncture resistance and tear resistance.

[0069] These comparisons together prove that the composite reinforcing agent composed of surface modified precipitated silica and acid-treated aramid pulp and the synergistic effect of its internal components are critical to improving the mechanical properties of the material. Comparative Example 8 shows that the composite reinforcing agent is necessary to significantly improve the strength and toughness as a whole. Comparative Examples 9 and 10, by removing a single component in the composite reinforcing agent, respectively show that precipitated silica provides a rigid 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 its synergistic effect. These comparative examples prove that precipitated silica and aramid pulp have a synergistic reinforcement effect, which together improves the puncture resistance and tear resistance of rubber gloves.

[0070] Test Example 4 Test objects: Example 1, Example 6, Examples 8-9 and Comparative Examples 11-14.

[0071] Test method: Refer to test examples 1-3 for the test method. The final test results are shown in Tables 4-6.

[0072] Table 4 Radiation protection performance test results of Example 1, Example 6, Examples 8-9 and Comparative Examples 11-14 Table 5 Anti-penetration performance test results of Example 1, Example 6, Examples 8-9 and Comparative Examples 11-14 Table 6 Mechanical hazard protection performance test results of Example 1, Example 6, Examples 8-9 and Comparative Examples 11-14 Processing aids monoglyceride stearate, zinc stearate and paraffin oil synergistically modify the rubber matrix, greatly improving the processability of the rubber compound in the multi-stage internal mixing and open mixing 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 highly uniform dispersion of fillers and a defect-free matrix, improving radiation protection uniformity, anti-permeability and mechanical properties.

[0073] Comparative Example 11: When all of the ultra-high filling radiation shielding powder dispersant was added to the internal mixer at once, the viscosity of the rubber compound increased instantaneously, making it difficult for processing aids to effectively wet and coat, and it was difficult for the high shear in the internal mixer to promote the deagglomeration and uniform dispersion of the filler; the impurities of undispersed agglomerates increased, and the purity and uniformity of the mixed rubber became worse; the uneven dispersion of the filler directly affected the radiation shielding uniformity, the interfacial defects of the 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 mill stage was relatively low; when a large amount of radiation shielding powder dispersant was added at once at this stage, it was difficult for processing aids to quickly and effectively wet and coat, and it was difficult for the low shear of the open mill to break up the filler agglomerates in the high-viscosity system and disperse them evenly; the uneven dispersion of the filler directly affected the radiation shielding uniformity, the interfacial defects of the 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 ultra-high filling fillers decreased, and it was difficult to overcome the frictional cohesion tendency between filler particles; even if multi-stage mixing and filtration were carried out, it was impossible to maximize the deagglomeration and uniform dispersion of the filler; the uneven dispersion of the filler directly affected the radiation shielding uniformity, the interfacial defects of the 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 the filler distribution was damaged, directly affecting the radiation shielding uniformity, the internal defects of the material increased, the anti-permeability decreased, and the stress concentration defects expanded, resulting in a decrease in mechanical properties.

[0074] These comparisons jointly reveal the synergistic effect of processing aids, multi-stage mixing process, and filtration process in solving the ultra-high filling processing problems and improving the quality of the mixed rubber. Comparative Example 13 shows that the key to realizing the preliminary wetting of the filler and reducing the viscosity is the composite processing aids. Comparative Examples 11 and 12 show that by changing the way of adding the filler, even with a dispersant, adding the ultra-high filling amount of filler in stages and using the characteristics of internal mixing and open milling 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.

[0075] 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 method for preparing tungsten-containing lead-free radiation-proof rubber gloves, characterized in that: The specific preparation steps are as follows: The radiation shielding powder was prepared using nano-tungsten powder and γ-methacryloxypropyltrimethoxysilane as raw materials; The modified EPDM rubber is prepared by reacting EPDM rubber with glycidyl methacrylate; The composite reinforcing agent is prepared by using precipitated silica and aramid pulp as raw materials; After the modified EPDM rubber is plasticized, an activator and an antioxidant are added to perform a first round of banburying, then carbon black, the composite reinforcing agent, the radiation shielding powder and a dispersant are added to perform a second round of banburying, and finally paraffin oil is added to perform a third round of banburying to obtain a crude mixed rubber; The crude mixed rubber, the radiation shielding powder, the dispersant, the vulcanizing agent and the vulcanizing aid are mixed and kneaded to obtain a film; the film is filtered, injection molded, two-stage vulcanized, washed and dried to obtain the tungsten-containing lead-free radiation-proof rubber gloves.

2. The method for preparing the tungsten-containing lead-free radiation-proof rubber gloves according to claim 1, characterized in that: The preparation method of the modified EPDM rubber is as follows: 95-105 parts by weight of the EPDM rubber are fed into a twin-screw extruder; 5-7 parts of a mixture of glycidyl methacrylate and 2,5-dimethyl-2,5-di-tert-butyl peroxyhexane are simultaneously 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.

3. The method for preparing the tungsten-containing lead-free radiation-proof rubber gloves according to claim 1, characterized in that: The preparation method of the radiation shielding powder comprises the following steps: dispersing the nano tungsten powder in a dilute nitric acid solution, stirring, centrifuging, washing and drying to obtain an acid pretreated nano tungsten powder; dispersing the acid pretreated nano tungsten powder in a mixed solution consisting of anhydrous ethanol and deionized water; adjusting the pH value to 4.5-5.5 using a dilute hydrochloric acid solution after ultrasonic dispersion to obtain a suspension; adding the gamma-methacryloxypropyltrimethoxysilane to the suspension, stirring for reaction for 2-2.5 hours; and centrifuging, washing and drying after the reaction to obtain the radiation shielding powder.

4. The method for preparing the tungsten-containing lead-free radiation-proof rubber gloves according to claim 3, characterized in that: In parts by weight, the added amount of the γ-methacryloxypropyltrimethoxysilane is 4-6% of the acid-pretreated nano-tungsten powder.

5. The method for preparing the tungsten-containing lead-free radiation-proof rubber gloves according to claim 1, characterized in that: The preparation method of the composite reinforcing agent is as follows: the precipitated silica is reacted with the γ-methacryloxypropyltrimethoxysilane to prepare modified precipitated silica; the 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.

6. The method for preparing the tungsten-containing lead-free radiation-proof rubber gloves according to claim 1, characterized in that: The preparation method of the crude rubber mix is ​​as follows: The temperature of the plasticizing is 70-80°C, and the time of the plasticizing is 8-10 minutes; The temperature of the first mixing step is 80-90°C, and the time of the first mixing step is 6-8min; The temperature of the second kneading is 80-90°C, and the time of the second kneading is 10-15min; The temperature of the third kneading is 90-100° C., and the time of the third kneading is 5-9 minutes.

7. The method for preparing the tungsten-containing lead-free radiation-proof rubber gloves according to claim 1, characterized in that: The preparation method of the film is as follows: according to parts by weight, the coarse mixed rubber is moved to an open mill with a roller 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 vulcanizing aid are added; and the rubber is cut, turned and calendered repeatedly to obtain the film.

8. The method for preparing the tungsten-containing lead-free radiation-proof rubber gloves according to claim 1, characterized in that: The two-stage vulcanization process is as follows: the rubber strip is obtained after filtering the rubber sheet, and the rubber strip is preheated and formed, and then subjected to primary vulcanization, with the temperature set at 155-165° C. and maintained for 8-10 minutes; the gloves after primary vulcanization are cooled and subjected to secondary vulcanization, with the secondary vulcanization temperature being 130-140° C. and the secondary vulcanization time being 20-30 minutes.

9. A tungsten-containing lead-free radiation-proof rubber glove prepared by the preparation method of claim 1, characterized in that: The raw materials for preparing the tungsten-containing lead-free radiation-proof rubber gloves include: modified EPDM rubber, activator, antioxidant, carbon black, composite reinforcing agent, radiation shielding powder, dispersant, paraffin oil, vulcanizing agent, and vulcanizing accelerator; The active agent is a mixture of zinc oxide and stearic acid; the antioxidant is antioxidant 1010; the carbon black is carbon black N660; the dispersant is stearic acid monoglyceride; the vulcanizing agent is diisopropylbenzene peroxide; and the vulcanization aid is triallyl isocyanurate.

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