阅读说明：本技术 一种柔性中子辐射防护材料及防护用品制备方法 (Flexible neutron radiation protection material and preparation method of protection article ) 是由 王英 曹磊 兰长林 戚大军 郭少嘉 林志凯 洪博 戚玮 许凤奎 潘小东 于 2019-11-26 设计创作，主要内容包括：本发明公开了一种柔性中子辐射防护材料,所述材料包括4层结构,第1层结构的材料为10-40重量份的稀土矿粉、1-20重量份的钨镍合金和50-90重量份的天然橡胶,第2层结构的材料为5-20重量份的稀土矿粉、50-80重量份的天然橡胶,5-20重量份的铝,5-30重量份的钨镍合金；第3层结构的材料为50-100重量份的天然橡胶,5-25重量份的铝,5-40重量份的钨镍合金；第4层结构的材料为1-10重量份的钆、50-85重量份的天然橡胶,20-40重量份的铝,2-10重量份的B<Sub>4</Sub>C。本发明的材料具有一定的耐辐照性能,特别是工作在核反应堆等强中子辐射源附近,存在复杂核辐射背景的场所中,可满足人员、设备和装置的辐射防护要求。(The invention discloses a flexible neutron radiation protection material, which comprises a 4-layer structure, wherein the material of the 1 st layer structure comprises 10-40 parts by weight of rare earth mineral powder, 1-20 parts by weight of tungsten-nickel alloy and 50-90 parts by weight of natural rubber, and the material of the 2 nd layer structure comprises 5-20 parts by weight of rare earth mineral powder, 50-80 parts by weight of natural rubber, 5-20 parts by weight of aluminum and 5-30 parts by weight of tungsten-nickel alloy; the material of the layer 3 structure is 50-100 parts by weight of natural rubber and 5-25 parts by weight ofAluminum, 5-40 parts by weight of tungsten-nickel alloy; the material of the 4 th layer structure comprises 1-10 parts by weight of gadolinium, 50-85 parts by weight of natural rubber, 20-40 parts by weight of aluminum and 2-10 parts by weight of B 4 C. The material has certain radiation resistance, and can meet the radiation protection requirements of personnel, equipment and devices particularly when working near strong neutron radiation sources such as nuclear reactors and the like and in places with complex nuclear radiation backgrounds.)

1. A flexible neutron radiation protection material characterized by: the material comprises a 4-layer structure, wherein the material of the 1 st layer structure comprises 10-40 parts by weight of rare earth ore powder, 1-20 parts by weight of tungsten-nickel alloy and 50-90 parts by weight of natural rubber, and the material of the 2 nd layer structure comprises 5-20 parts by weight of rare earth ore powder, 50-80 parts by weight of natural rubber, 5-20 parts by weight of aluminum and 5-30 parts by weight of tungsten-nickel alloy; the material of the layer 3 structure comprises 50-100 parts by weight of natural rubber, 5-25 parts by weight of aluminum and 5-40 parts by weight of tungsten-nickel alloy; the material of the 4 th layer structure comprises 1-10 parts by weight of gadolinium, 50-85 parts by weight of natural rubber, 20-40 parts by weight of aluminum and 2-10 parts by weight of B₄C。

2. The neutron radiation protection material of claim 1, wherein: the thickness of the 1 st layer structure is 0.1-1 cm; the thickness of the 2 nd layer structure and the 3 rd layer structure is 0.1-1 cm; the thickness of the 4 th layer structure is 0.1-2 cm; the preferred thickness of the layer 1 structure is 0.3 cm; the thickness of the 2 nd layer structure and the 3 rd layer structure is 0.3 cm; the thickness of the 4 th layer structure is 0.5 cm; or the thickness of the 1 st layer structure is 0.5 cm; the thickness of the 2 nd layer structure and the 3 rd layer structure is 0.4 cm; the thickness of the 4 th layer structure is 0.9 cm; or the thickness of the 1 st layer structure is 0.8 cm; the thickness of the 2 nd layer structure and the 3 rd layer structure is 0.6 m; the thickness of the layer 4 structure was 1.5 cm.

3. The neutron radiation protection material of claim 1 or 2, wherein: the material comprises a 4-layer structure, wherein the material of the 1 st layer structure comprises 20-35 parts by weight of rare earth mineral powder, 1-10 parts by weight of tungsten-nickel alloy and 55-80 parts by weight of natural rubber; the material of the layer 2 structure comprises 5-18 parts by weight of rare earth mineral powder, 52-76 parts by weight of natural rubber, 6-18 parts by weight of aluminum and 8-28 parts by weight of tungsten-nickel alloy; the material of the layer 3 structure comprises 60-95 parts by weight of natural rubber, 6-20 parts by weight of aluminum and 6-25 parts by weight of tungsten-nickel alloy; the material of the layer 4 structure comprises 2-8 parts by weight of gadolinium, 52-78 parts by weight of natural rubber, 22-38 parts by weight of aluminum and 3-9 parts by weight of B₄C。

4. The neutron radiation protection material of claim 2, wherein: the material of the layer 1 structure comprises 30 parts by weight of rare earth mineral powder, 65 parts by weight of natural rubber and 5 parts by weight of tungsten-nickel alloy; the material of the layer 2 structure comprises 10 parts by weight of mineral powder, 60 parts by weight of natural rubber, 10 parts by weight of aluminum and 20 parts by weight of tungsten-nickel alloy; the material of the layer 3 structure comprises 80 parts by weight of natural rubber, 10 parts by weight of aluminum and 20 parts by weight of tungsten-nickel alloy; the material of the 4 th layer structure comprises 5 parts by weight of gadolinium, 60 parts by weight of natural rubber, 30 parts by weight of aluminum and 5 parts by weight of B₄C。

5. The neutron radiation protection material of claim 2, wherein: the material of the layer 1 structure comprises 35 parts by weight of rare earth mineral powder, 6 parts by weight of tungsten-nickel alloy and 75 parts by weight of natural rubber; the material of the layer 2 structure comprises 15 parts by weight of rare earth mineral powder, 70 parts by weight of natural rubber, 9 parts by weight of aluminum and 18 parts by weight of tungsten-nickel alloy; the material of the layer 3 structure comprises 70 parts by weight of natural rubber, 15 parts by weight of aluminum and 15 parts by weight of tungsten-nickel alloy; the material of the layer 4 structure comprises 6 parts by weight of gadolinium, 70 parts by weight of natural rubber, 25 parts by weight of aluminum and 8 parts by weight of B₄C。

6. The neutron radiation protection material of claim 2, wherein: the material of the layer 1 structure comprises 22 parts by weight of rare earth mineral powder, 2 parts by weight of tungsten-nickel alloy and 65 parts by weight of natural rubber; the material of the layer 2 structure comprises 10 parts by weight of rare earth mineral powder, 60 parts by weight of natural rubber, 16 parts by weight of aluminum and 10 parts by weight of tungsten-nickel alloy; the material of the layer 3 structure comprises 90 parts by weight of natural rubber, 5 parts by weight of aluminum and 20 parts by weight of tungsten-nickel alloy; the material of the layer 4 structure is 7 parts by weight of gadolinium, 60 parts by weight of natural rubber, 25 parts by weight of aluminum and 7 parts by weight of B₄C。

7. The neutron radiation protection material of any of claims 1 to 6, wherein: the anti-aging agent also comprises a compounding agent, wherein the compounding agent comprises 10-20 parts by weight of grease, 5-10 parts by weight of stearic acid, 1-10 parts by weight of an anti-aging agent, 1-10 parts by weight of a promoter and 1-5 parts by weight of a processing aid; the gadolinium is gadolinium oxide.

8. The neutron radiation protection material of claim 7, wherein: the oil is hydrocarbon or aromatic hydrocarbon oil with the molecular weight of 300-600, preferably one or more of engine oil, paraffin oil and paraffin oil; the stearic acid is one or more of titanate, aluminate and a polymer coupling agent; the anti-aging agent is phenol 1010, 1076; thiodipropionate DLTP, DSTP or phosphite 168; the accelerator is sulfur added with one or more of thiazoles, sulfenamides, thiurams and guanidine; the processing aid comprises low molecular esters and high molecular esters, and is preferably glycol adipate.

9. The method of preparing a neutron radiation protection material of claim 7, wherein the steps include:

(1) cutting and cleaning natural rubber;

(2) placing rare earth oxide in a reaction crucible, adding deionized water, heating to over 80 ℃, then adding nitric acid and stirring until the solution becomes clear, testing the pH value by using filter paper, adding NaOH solution, adjusting the pH value to be neutral, and dehydrating until rare earth nitrate is crystallized and separated out for later use;

(3) preparing an acrylic acid rare earth metal polymer by using a polymerization reaction;

(4) starting a pressurized kneading machine, and adding grease, acrylic acid natural rare earth mineral powder polymer, stearic acid, an anti-aging agent, sulfur, an accelerator and a processing aid; aluminum powder, tungsten-nickel alloy powder, B₄C, mixing the powder C;

(5) adding natural rubber, continuously mixing, and discharging;

(6) putting the mixed rubber material into a rubber mixing machine to be beaten into triangular bags, and continuously blending and rolling the material;

(7) putting the hot rubber material into an open mill, and rolling;

(8) a material roll is put into a feed port of the extruder and enters a calender through a feeding device;

(9) starting the calender, uniformly distributing the rubber material between an upper roller and a middle roller of the calender, cooling the rubber material by a cooling roller, and then coiling the rubber material by a coiling device;

(10) a pull tab.

10. The method of preparing a neutron radiation protection material of claim 8, wherein:

in the step (2), the mass ratio of the NaOH solution is 3-8%;

in the step (4), the mixing time is 2-10 min, and the temperature is 60-120 ℃;

in the step (6), the roller spacing and the roller temperature of the rubber mixing mill are adjusted to be 2-6 mm, the roller temperature is not more than 50-60 ℃, the cutter turns over the sheet, and the material is uniformly mixed and rolled;

putting the heated rubber material into an open mill in the step (7), and rolling the rubber material into a roll with the thickness of 5-6 cm;

the step (9) starts the calender, sets the water temperature, adjusts the roller spacing, and controls the calendering thickness to be 0.3 cm-0.5 cm; the water temperature is 30-60 ℃; the width of the rubber material is 650-1300 m, the rubber material is uniformly distributed between an upper roller and a middle roller of a calender, and the rubber material enters a cooling roller for cooling and then enters a coiling device for coiling;

in the step (10), the no-load pressure of the steel belt of the vulcanizing machine is 12MPa, the no-load pressure of the steel belt of the vulcanizing machine during vulcanization is 12-14MPa, vulcanization is started after the temperature is raised to the vulcanization required temperature of 80-140 ℃ at the initial time of vulcanization, the vulcanization speed is 2/3 of the normal vulcanization speed, the rubber condition is observed after the rubber is discharged from a vulcanization roller, the revolution of the vulcanizing machine is gradually adjusted, and the normal vulcanization speed is reached within 0.5-1 hour; discharging the sheet at a normal vulcanization speed; the normal vulcanization speed is preferably 1 m/2-6 min

And (3) adjusting the aggregate proportion, repeating the steps (1) to (10), respectively processing 4 layers of structural materials, adjusting a three-roller calender, determining the width and thickness of the rubber sheet, and laminating and pressing to obtain the final 4 layers of structural protective materials.

Technical Field

The invention relates to a radiation protection material, in particular to a flexible neutron radiation protection material and a preparation method of a protection article.

Background

The rapid development of the nuclear energy and nuclear technology application industry promotes the continuous progress of the manufacturing technology of the radiation protection material. From the perspective of broad radiation protection, radiation protection materials refer to materials that can absorb or dissipate radiation energy and protect human bodies or instruments and equipment, and are generally classified into ionizing or electromagnetic radiation protection materials according to the type of radiation protection, and also classified into rigid (such as concrete protection walls, lead steel protection materials, glass bodies, and the like) or flexible (such as lead-containing protection rubbers, resins, and the like) protection materials according to the material properties. In the traditional radiation protection material, a large amount of lead, cadmium, chromium, phenols, epoxy resin organic matters and the like are used as main components, and the traditional radiation protection material has the advantages of high occupation ratio of toxic and harmful substances, high biological toxicity, strong environmental side effect and low cost performance. On the other hand, unlike rigid radiation protection materials, flexible radiation protection materials are suitable for some special application sites, especially for equipment and various pipelines requiring a large amount of manual installation and maintenance near nuclear reactors or medical and industrial nuclear facilities, and workers may be exposed to excessive neutrons and induced radiation thereof when contacting radioactive substances or radiation source items in a short distance. The radiation protection tool and article made of flexible materials can reduce the radiation dose and the radiation hazard level thereof under the condition of not influencing the operation of personnel as much as possible; on the other hand, with the rapid development of the technical fields of modular small reactors (SMR), research fast neutron reactors, small nuclear power reactors, commercial nuclear reactors and nuclear technology applications, aerospace radiation protection, military weapons, etc., the instruments and equipment need to be wholly or partially reinforced with nuclear radiation shielding protection (nuclear radiation aging resistance and reinforcement) to protect their normal functions. The rigid radiation protection material is limited by the geometric dimensions of internal and external spaces with different requirements on shape and performance, and cannot meet special radiation protection requirements. Therefore, the research and development of flexible radiation protection materials and technologies are increasingly paid attention by radiation protection related organizations at home and abroad.

From the development perspective of radiation protection technology, the research and development of a new generation of radiation protection material with human body and environment-friendly characteristics, high comprehensive protection performance and good mechanical performance is also urgently needed. The development and development of the flexible radiation protection material have important significance for national defense and civil use, have huge potential market and are expected to have considerable economic benefit.

From the material property perspective, the traditional flexible radiation protection material usually takes lead-boron rubber products which are natural raw rubber particles as fillers, lead powder, boron carbide powder and other materials and fibers as aggregates, and additives are added to form the neutron protection material. The main processing technology comprises the following steps: the preparation method comprises the steps of firstly, plasticating and other processes to enable elastic rubber to become plasticated rubber with plasticity, mixing aggregate and compounding agents to prepare a semi-finished product, and then promoting reactions such as coordination reaction, ionic bonding and the like through technical processes such as heating, cooling and the like to prepare products such as flexible radiation protection lead rubber and the like. The rubber processing is a process for solving the contradiction between plasticity and elasticity of the material, and the production process comprises the basic procedures of banburying, mixing, calendering, extruding, forming, vulcanizing and the like. When the radiation shielding material is selected, in addition to the shielding performance of rays, the thermodynamic performance, the mechanical performance and some special physical properties of the material are also factors to be considered, and boron carbide, borate and the like have larger neutron absorption cross sections and are widely used for the synthesis and preparation of the neutron shielding material. The fiber reinforced epoxy resin-based composite material containing a large amount of hydrogen nuclei and other low-atomic-number elements and the high-density polyethylene containing boron carbide can effectively decelerate neutrons and improve the probability of neutron capture by boron nuclides, so that the material has a good neutron shielding effect, but the increase of the content of boron and other impurities can influence the physical properties of the material, such as compression resistance, flexural strength and the like, and aggravate the contradiction between the structural stability and the ray protection effect.

High-density polyethylene containing lead, cadmium and boron and the like are mainstream products of traditional neutron radiation protection and are still widely used, but the high-density polyethylene can not meet the increasingly rigorous requirement of radiation protection. From the perspective of mechanical properties, the physical blending method is adopted, aggregates such as lead, cadmium, chromium, boron and the like are added into polymer matrixes such as benzene, phenol epoxy organic matters, polyethylene and the like, and the method is a common method for manufacturing radiation protection materials at present. These micron and even millimeter sized fillers act like impurities, which greatly degrade the mechanical properties of the material. B in the micron and above size₄The content of C/BN increases, resulting in the content of B₄The tensile and flexural strength of the C/BN high density polyethylene HDPE decreases. In addition, from the viewpoint of the nuclear reaction mechanism, it is that boron isotopes contribute to the absorption of neutrons¹⁰B, which has a higher thermal neutron reaction cross section (0.0253eV, about 3840B), but because of the higher thermal neutron reaction cross section¹⁰The natural abundance of B is about 20%, (¹¹B accounts for about 80%), and the reaction cross section of fast neutrons and neutron energy is very small, so that the utilization efficiency of materials is not high. On the other hand, neutrons and¹⁰the reaction product of B is lithium nucleus and helium gas⁴He). The deposited radiation energy will cause material change and gas swelling effect of the protective material under the effect of neutron bombardment for a long timeObviously, the service life of the protective material is shorter. Meanwhile, the high-density polyethylene material has very high hydrogen nucleus component, and when the high-density polyethylene material is used as a moderator or shielding material, thermal neutron bombardment is easy to cause¹The radiation of the H nuclear species is used for trapping reaction,¹H(n,γ)²h releases high-energy gamma rays (E is approximately equal to 2.2MeV), and is not suitable for radiation protection of high-flux medium-energy and low-energy neutrons. The lead nuclide has an atomic number of 82 and a mass density of 11.3g/cm³The absorption limit of the lead K shell is 88keV, the absorption limit of the L layer is 40keV, and a photon weak absorption area (40 keV-88 keV) exists, so that the secondary inelastic scattering and the captured photons are not protected. In addition, lead, cadmium, chromium and other heavy metals have high biotoxicity, lead and compounds thereof can be deposited in human bones and brain organs for a long time to replace calcium in calcium phosphate to cause biological damage, and cadmium and chromium compounds can cause cancers; the lead alloy also has the characteristics of relatively low melting point and low Mohs hardness, has poor machining performance, and belongs to the radiation protection materials to be eliminated.

Disclosure of Invention

The invention aims to disclose a flexible neutron radiation protection material and a preparation method of a protection article.

The purpose of the invention is realized by the following technical scheme:

a flexible neutron radiation protection material comprises a 4-layer structure, wherein the material of the 1 st layer structure comprises 10-40 parts by weight of rare earth mineral powder, 1-20 parts by weight of tungsten-nickel alloy and 50-90 parts by weight of natural rubber, and the material of the 2 nd layer structure comprises 5-20 parts by weight of rare earth mineral powder, 50-80 parts by weight of natural rubber, 5-20 parts by weight of aluminum and 5-30 parts by weight of tungsten-nickel alloy; the material of the layer 3 structure comprises 50-100 parts by weight of natural rubber, 5-25 parts by weight of aluminum and 5-40 parts by weight of tungsten-nickel alloy; the material of the 4 th layer structure comprises 1-10 parts by weight of gadolinium oxide, 50-85 parts by weight of natural rubber, 20-40 parts by weight of aluminum and 2-10 parts by weight of B₄C。

The thickness of the layer 1 structure of the neutron radiation protection material is 0.1-1 cm; the thickness of the 2 nd layer structure and the 3 rd layer structure is 0.1-1 cm; the thickness of the 4 th layer structure is 0.1-2 cm; the preferred thickness of the layer 1 structure is 0.3 cm; the thickness of the 2 nd layer structure and the 3 rd layer structure is 0.3 cm; the thickness of the 4 th layer structure is 0.5 cm; or the thickness of the 1 st layer structure is 0.5 cm; the thickness of the 2 nd layer structure and the 3 rd layer structure is 0.4 cm; the thickness of the 4 th layer structure is 0.9 cm; or the thickness of the 1 st layer structure is 0.8 cm; the thickness of the 2 nd layer structure and the 3 rd layer structure is 0.6 m; the thickness of the layer 4 structure was 1.5 cm.

Further, the neutron radiation protection material comprises a 4-layer structure, wherein the material of the 1 st layer structure comprises 20-35 parts by weight of rare earth mineral powder, 1-10 parts by weight of tungsten-nickel alloy and 55-80 parts by weight of natural rubber; the material of the layer 2 structure comprises 5-18 parts by weight of rare earth mineral powder, 52-76 parts by weight of natural rubber, 6-18 parts by weight of aluminum and 8-28 parts by weight of tungsten-nickel alloy; the material of the layer 3 structure comprises 60-95 parts by weight of natural rubber, 6-20 parts by weight of aluminum and 6-25 parts by weight of tungsten-nickel alloy; the material of the layer 4 structure comprises 2-8 parts by weight of gadolinium, 52-78 parts by weight of natural rubber, 22-38 parts by weight of aluminum and 3-9 parts by weight of B₄C。

The neutron radiation protection material can also be prepared by using the material of the layer 1 structure comprising 30 parts by weight of rare earth mineral powder, 65 parts by weight of natural rubber and 5 parts by weight of tungsten-nickel alloy; the material of the layer 2 structure comprises 10 parts by weight of mineral powder, 60 parts by weight of natural rubber, 10 parts by weight of aluminum and 20 parts by weight of tungsten-nickel alloy; the material of the layer 3 structure comprises 80 parts by weight of natural rubber, 10 parts by weight of aluminum and 20 parts by weight of tungsten-nickel alloy; the material of the 4 th layer structure comprises 5 parts by weight of gadolinium, 60 parts by weight of natural rubber, 30 parts by weight of aluminum and 5 parts by weight of B₄C。

Preferably, the neutron radiation protection material has a layer 1 structure comprising 35 parts by weight of rare earth mineral powder, 6 parts by weight of tungsten-nickel alloy and 75 parts by weight of natural rubber; the material of the layer 2 structure comprises 15 parts by weight of rare earth mineral powder, 70 parts by weight of natural rubber, 9 parts by weight of aluminum and 18 parts by weight of tungsten-nickel alloy; the material of the layer 3 structure comprises 70 parts by weight of natural rubber, 15 parts by weight of aluminum and 15 parts by weight of tungsten-nickel alloy; the material of the layer 4 structure comprises 6 parts by weight of gadolinium, 70 parts by weight of natural rubber, 25 parts by weight of aluminum and 8 parts by weight of B₄C。

The neutron radiation protection material can also be prepared by the following steps that the material of the layer 1 structure comprises 22 parts by weight of rare earth mineral powder, 2 parts by weight of tungsten-nickel alloy and 65 parts by weight of natural rubber; the material of the layer 2 structure comprises 10 parts by weight of rare earth mineral powder, 60 parts by weight of natural rubber, 16 parts by weight of aluminum and 10 parts by weight of tungsten-nickel alloy; the material of the layer 3 structure comprises 90 parts by weight of natural rubber, 5 parts by weight of aluminum and 20 parts by weight of tungsten-nickel alloy; the material of the layer 4 structure is 7 parts by weight of gadolinium, 60 parts by weight of natural rubber, 25 parts by weight of aluminum and 7 parts by weight of B₄C。

The anti-aging agent also comprises a compounding agent, wherein the compounding agent comprises 10-20 parts by weight of grease, 5-10 parts by weight of stearic acid, 1-10 parts by weight of an anti-aging agent, 1-10 parts by weight of a promoter and 1-5 parts by weight of a processing aid; the gadolinium is gadolinium oxide.

Further, the oil is hydrocarbon or aromatic hydrocarbon oil with the molecular weight of 300-600, preferably one or more of engine oil, paraffin oil and paraffin oil; the stearic acid is one or more of titanate, aluminate and a polymer coupling agent; the anti-aging agent is phenol 1010, 1076; thiodipropionate DLTP, DSTP or phosphite 168; the accelerator is sulfur added with one or more of thiazoles (DM, M), sulfenamides (CZ, NOBS), thiurams (TETD, TMTM, TMTD) and guanidine (D); the processing aid comprises low molecular esters (DOP, DBP, DOS) and high molecular esters, and is preferably glycol adipate.

The preparation method of the neutron radiation protection material comprises the following steps:

(1) cutting and cleaning natural rubber;

(2) preparing stable dispersed superfine particle size nano-particles of natural rare earth metals such as rare earth gadolinium oxide, europium oxide and the like in the process of processing aggregate and compounding agents, which is a key link for improving the mechanical property and the protective property of the material, placing rare earth oxides in a reaction crucible, adding deionized water, heating to over 80 ℃, then adding nitric acid, stirring until the solution becomes clear, testing the pH value by using filter paper, adding NaOH solution, wherein the preferred mass ratio is 3-8%, and dehydrating after the pH value is adjusted to be neutral until the rare earth nitrate is crystallized and separated out for later use;

(3) the reaction for preparing the acrylic acid rare earth metal polymer (ES-GON-PAA) by utilizing the polymerization reaction is as follows: taking gadolinium oxide as an example:

rare earth oxides can be dispersed in the acrylic polymer in the nano form according to the methods provided in the references Excedingly Small Garolinium Oxide NanoparticleswitchRemarkable Relaxivities for Magnetic Resonance Imaging of Tumors. Zheyu Shen, Wenpei Fan, Zhen Yang, etc. Small, Volume15, Issue41, October8,2019: 1903422.

(4) Starting a pressurized kneading machine, and adding grease, acrylic acid natural rare earth mineral powder polymer, stearic acid, an anti-aging agent, sulfur, an accelerator and a processing aid; aluminum powder, tungsten-nickel alloy powder and B4C powder are mixed;

(5) adding natural rubber, continuously mixing, and discharging;

(6) putting the mixed rubber material into a rubber mixing machine to be beaten into triangular bags, and continuously blending and rolling the material;

(7) putting the hot rubber material into an open mill, and rolling;

(8) a material roll is put into a feed port of the extruder and enters a calender through a feeding device;

(9) starting the calender, uniformly distributing the rubber material between an upper roller and a middle roller of the calender, cooling the rubber material by a cooling roller, and then coiling the rubber material by a coiling device;

(10) a pull tab;

further, in the step (4), the mixing time is 2-10 min, and the temperature is 60-120 ℃;

further, in the step (6), the roller spacing and the roller temperature of the rubber mixing mill are adjusted to be 2-6 mm, the roller temperature is not more than 50-60 ℃, the cutter turns over the sheets, and the materials are uniformly mixed and rolled;

further, the heated rubber material is put into an open mill in the step (7), and the thickness of the roll is 5-6 cm;

preferably, the calender is started in the step (9), the water temperature is set, the roller spacing is adjusted, and the calendering thickness is 0.3 cm-0.5 cm; the water temperature is 30-60 ℃; the width of the rubber material is 650-1300 m, the rubber material is uniformly distributed between an upper roller and a middle roller of a calender, and the rubber material enters a cooling roller for cooling and then enters a coiling device for coiling;

in the step (10), the no-load pressure of a steel belt of the vulcanizing machine is 12MPa, the (12-14) MPa is automatically determined according to the thickness of a rubber sheet during vulcanization, the vulcanization is started after the temperature is raised to the vulcanization required temperature of 80-140 ℃, the vulcanization speed is 2/3 of the normal vulcanization speed, the rubber condition is observed after the rubber sheet is discharged from a vulcanization roller, the revolution of the vulcanizing machine is gradually adjusted, and the normal vulcanization speed is reached within 0.5-1 hour; discharging the sheet at a normal vulcanization speed;

and (3) adjusting the aggregate proportion, repeating the steps (1) to (10), respectively processing 4 layers of structural materials, adjusting a three-roller calender, determining the width and thickness of the rubber sheet, and laminating and pressing to obtain the final 4 layers of structural protective materials.

From the nuclear physics, the effect of the neutron and the outer layer electron of the substance atom is negligible, and potential scattering, direct interaction and composite nucleus are 3 modes of the neutron and the atomic nucleus. (1) Neutrons of any energy can transfer energy to target nuclei by a potential scattering reaction to form recoil nuclei, so that kinetic energy of the target nuclei is increased, and at the same time, the neutrons change the direction and energy of motion. The conservation of system kinetic energy and momentum, which is formed by neutrons and target nuclei before and after potential scattering, is the process of energy degradation of neutrons through elastic scattering. (2) The direct interaction of nuclei is a nuclear reaction in which an incident neutron directly acts on a target nucleus to excite the nucleus from the nucleus and the neutron remains in the target nucleus, and is called a direct elastic scattering reaction when the excited nucleus is a proton and is denoted as (n, p) reaction, and is called a direct inelastic scattering reaction when the excited nucleus returns from an excited state to a ground state and emits gamma rays when the excited neutron and is denoted as (n, n' gamma). (3) The most extensive and main mode of action of neutrons and atomic nuclei is to form a composite nucleus, incident neutrons are absorbed by target nuclei to form a new nucleus (composite nucleus), the total kinetic energy of the neutrons and the mass core system of the target nuclei is converted into the internal energy of the composite nucleus, meanwhile, the binding energy of the neutrons and the target nuclei is also transferred to the composite nucleus, the composite nucleus is in an excited state or an excited state energy level above a ground state after the action, and the composite nucleus decays or cracks for a period of time to release secondary particles or photons.

The optimized action mechanism of neutron protection is that neutrons are scattered (neutrons are slowed down, decelerated and energy-reduced) firstly, then the slow neutrons are absorbed (neutrons disappear), and secondary rays generated by reaction are shielded, so that the purpose of radiation protection is achieved. Neutron scattering is a neutron kinetic energy reduction of the main nuclear reactions, including elastic and inelastic scattering (threshold energy reactions). In general, light nuclear neutron excitation energy is higher, and heavy nuclear excitation energy is lower. The greater the mass ratio between incident neutrons and target nuclei and the higher the energy, the far higher the probability of inelastic scattering than elastic scattering, but even if such as²³⁸The heavy nuclei of U also need to generate inelastic scattering (threshold energy reaction) when the incident neutron energy E is more than 45keV, which indicates that fast neutron moderation needs to be reduced to a certain energy range through inelastic scattering first, and then can be further reduced through elastic scattering, the smaller the mass of the atomic nuclei in elastic scattering, the larger the incident neutron energy loss or the recoil kinetic energy obtained by the atomic nuclei, the smallest the nuclear mass of hydrogen atoms, the neutron energy loss and the largest the recoil kinetic energy obtained by the hydrogen atoms, i.e., indicating that the material with high hydrogen content has the best effect on neutron moderation with lower energy, the neutron absorption reactions mainly include radiation capture (n, gamma), charged particle reactions (n, α) and (n, p), nuclear fission (n, f), and the like, and the neutron absorption cross section of the common nuclide can be generally divided into 3 energy regions:

(1) the low energy region E is less than 1eV, the absorption cross section (reaction probability) is increased along with the reduction of the neutron energy, and the reaction probability and the neutron velocity are 1/v. v is the neutron velocity, in m/s;

(2) the middle energy area is 1eV < E < 10³eV, one or more resonance absorption peaks exist in the nuclide absorption cross section, the neutron absorption cross section is suddenly increased at the resonance peak, and a resonance absorption band exists;

(3) the fast neutron area E is more than 100keV, the absorption cross section is usually very small, and the variation with energy is small.

Neutron spectrum, thermal neutrons (energy 1 × 10) in nuclear reactor sites and medical linear accelerator sites, unlike neutron radiation fields formed by radioisotopes^-7～1×10^-8MeV) and the neutron energy (0.1-1 MeV) are more outstanding, and the fast neutron (MeV-level energy) share is lower, namely the structural design of the neutron protection material applied to the places mainly adopts elastic scattering energy reduction and assists inelastic scattering energy reduction. The neutron spectrum of a typical nuclear reactor site is shown in figure 1, and the neutron spectrum of a medical linear accelerator is shown in figure 2.

In conclusion, the technical scheme of the invention optimizes the adoption of non-uniform multilayer protective materials to carry out moderation absorption on intermediate energy neutrons and thermal neutrons, and reduces the radiation dose caused by radiation capture gamma. The invention has the following beneficial effects:

(1) the flexible protective material should have good flexibility and resilience, high tear strength and be heat and moisture resistant. The natural rubber has better forming and processing characteristics, and can meet the mechanical and mechanical property requirements of materials when being used as a synthetic base material. Natural rubber [ C ]₅H₈]The n-agglomerated macromolecules have higher hydrogen-nuclear ratio, can further realize neutron deceleration by utilizing elastic scattering, and is an advantageous condition for using the n-agglomerated macromolecules as neutron protection materials. In the flexible neutron protection material, natural rubber is a main material

(2) Rare earth elements have excellent properties for neutron absorption, with the disadvantage of higher capture gamma energy, such as: the neutron average absorption cross section of gadolinium is 3.63X 10⁴(barn, Taran) neutron energy of 1.0X 10^-4Absorption cross section of 1.0X 10 at-0.1 eV³～8.0×10⁵b is, is¹⁰60 times of B. Samarium has a neutron average absorption cross section of 1.06X 10⁴b (unit: barn, target), neutron energy of 0.5X 10^-3Absorption cross section of 2.4X 10 at-0.3 eV³～2.0×10⁵b. Considering that the first layer of material has both the inelastic scattering energy reduction requirement of intermediate neutrons and a small amount of high-energy fast neutrons, the heavy metal in the natural rare earth has high specific gravity and has the function of moderating neutrons through inelastic scattering

(3) The second layer and the third layer of shielding bodies mainly have the functions of absorbing neutrons which are further reduced in energy through inelastic scattering and neutrons which are reduced in energy through elastic scattering, and absorbing gamma rays with various energies generated by inelastic scattering and radiation capture. The radiation absorption process can be divided mainly into 2 stages. The neutron is captured (neutron disappears) to form a composite nucleus which is the main reaction, the energy of the gamma ray generated by the neutron capture reaction is reduced through energy loss, and the reduced energy is approximately in direct proportion to the 4 th power of the atomic average number of the substance. In the energy absorption process, cascade secondary particles are generated to interact with outer layer electrons of atomic nuclei, the secondary particles are prevented in material lattices, and in the process that the outer layer electrons are continuously demagnetized after being excited from a ground state, reaction energy is dissipated in the material in the form of heat and the like, which is called particle absorption. In the shielding and protecting material, the main factor determining the gamma ray absorption capacity is the absorption limit of a K-L shell layer of the material, and the particle absorption is dominant by ionizing radiation near the absorption limit. The second and third layers of material are made of aluminum alloy and rare earth mixed material.

(4) The fourth layer of material is added with boron carbide and a small amount of natural rare earth, and mainly has the main functions of improving the thermal neutron capture capacity through (n, α) reaction by utilizing the high thermal neutron capture cross section of the B nuclide, and the proper amount of added iron and tungsten-nickel alloy mainly has the function of absorbing gamma rays generated by capture so as to achieve the purpose of radiation protection.

The acrylic acid rare earth metal salt has compatibility with natural rubber and can generate plasticizing effect. In the reactants, the size of the rare earth metal is in the nanometer range, the minimum particle size is 2 nanometers, and on the basis of considering the mechanical properties of the material, good quality dispersion is realized, and the utilization rate of the protective materials such as rare earth is improved.

The invention is created according to the actual requirement of personnel protection of the measured neutron radiation field distribution (high-share medium-energy and low-energy neutron radiation field) of nuclear reactors, accelerators and the like. Aiming at the defects of the traditional lead-boron-polyethylene or rubber material, the aggregate and the filler components are optimally designed. By utilizing reactions such as organic coordination and the like, rare earth metals are effectively dispersed in the protective material, and the problems of low neutron moderation ratio, poor absorption and poor protective effect of the flexible radiation protective material are solved.

The material has certain radiation resistance, and can meet the radiation protection requirements of personnel, equipment and devices particularly when working near strong neutron radiation sources such as nuclear reactors and the like and in places with complex nuclear radiation backgrounds.

The nano-particle dispersion of the heavy nuclide ensures that the flexible radiation protection material meets the requirements of physical and mechanical properties, thermal stability, wear resistance and corrosivity. The metal acrylate introduced into the rubber improves the crosslinking efficiency of peroxide, including crosslinking speed and crosslinking density, improves the structure of crosslinking bonds, introduces more ionic crosslinking bonds, powerfully improves the processability of the rubber, has lower processing viscosity of rubber compound, can be used as a reactive plasticizer, and better meets the requirements of physical and mechanical properties, thermal stability, wear resistance, corrosion resistance and the like.

The material of the invention does not adopt high-environment and human-body biohazard materials, and meets the requirements of environment and bio-friendly characteristics.

Description of the drawings:

FIG. 1: a neutron spectrum of a megawatt unit pressurized water nuclear reactor;

FIG. 2: treating planar neutron energy spectrum with a medical accelerator;

FIG. 3: the neutron shielding protection calculation model schematic diagram is provided, and the outermost layer is a layer 4;

FIG. 4: the transmittance of the 1 st layer of protective material is higher when the tungsten and the nickel are doped;

FIG. 5: the 2 nd, 3 rd and 4 th layer transmittance when doping tungsten and nickel;

FIG. 6: relative strength of neutrons with different energy after passing through the shield (tungsten-nickel alloy powder doping);

FIG. 7: the transmittance of the 1 st layer of protective material during aluminum doping;

FIG. 8: the transmittance of the 2 nd, 3 rd and 4 th layers of protective materials during aluminum doping;

FIG. 9: relative strength of neutrons with different energy after passing through the shielding body (aluminum alloy powder doping);

FIG. 10: relative intensity of photon gamma (doped aluminum alloy powder)

FIG. 11: relative intensity of photon γ ((doped tungsten-nickel alloy powder;

FIG. 12: neutron spectrum of interest behind each layer of shielding material.

Detailed Description

The following experimental examples and examples are intended to further illustrate but not limit the invention.

Experimental example 1:

1) a neutron source item: according to the practical radiation field neutron energy spectrum, an isotropic point neutron source is arranged at the right center of the shielding body in a simulation mode, the neutron energy is thermal neutrons of 0.0253eV and intermediate energy neutrons of 100keV (the neutron yield accounts for 70%: 30%).

2) Model and material composition were calculated. A hollow spherical shield with the inner diameter of 0.5cm and the outer diameter of 2.5cm is established, the shield is divided into 4 layers, the thickness of each layer is 0.5cm, the components in each layer are the same, but the proportions of the components in each layer are different, see Table 1, and the established shield and shield model is shown in figure 3. The rare earth mineral powder contains natural radioactive nuclide, including²³⁸U0.74％；²³²Th1.23％；²²⁶Ra0.51％；⁴⁰K1.13%, which is purchased from Sichuan river copper rare earth Limited liability company, wherein the natural rubber is a natural high molecular compound taking cis-1, 4-polyisoprene 2 alkene as a main component, the content of rubber hydrocarbon (cis-1, 4-polyisoprene 2 alkene) is more than 90%, and the natural rubber produced in Malaysia and Thai contains a small amount of protein, fatty acid, sugar, ash and the like;

TABLE 1 Mass constitution of Shielding Material Components of Point neutron Source (thermal and neutronic) models

3) Result analysis

2 kinds of energy neutrons generated by the point neutron source, 100keV neutrons and the 1 st layer shielding material interact, mainly scattering energy reduction reaction occurs, so that the number of low-energy neutrons is increased, and the total number of neutrons penetrating the 1 st layer is increased. The transmittance (the count without shield at the point of interest is defined as 1, the ratio of the count with shield to the count without shield) is greater than 1, see fig. 5. The neutron transmittance of the 2 nd, 3 rd and 4 th layers of shields is less than 1, which illustrates the shielding and protecting effects of the flexible radiation protection material, and is shown in figure 4.

Calculating neutron penetration through 4 layers using Monte Carlo methodNeutron flux 5cm behind the composite shield plate made up of shields, see fig. 6. It can be seen that the relative intensity of thermal neutrons (0.0253eV) at 5cm has decayed to 10^-13Of the order of magnitude, the relative intensity of the intermediate energy neutrons (100keV) has been attenuated to 10^-4And the magnitude reflects good shielding and protection effects.

4) And (6) evaluating the results. The product in the market for neutron radiation protection of the field mainly aims at thermal neutron protection, and for the protective material of neutrons with energy above the medium energy, the best product reaches the transmittance of about 0.44. The relative intensity of neutron counting of the product at 5cm is 0.0006, which is far superior to the mainstream products in the market.

Experimental example 2:

1) a neutron source item: according to the practical radiation field neutron energy spectrum, an isotropic point neutron source is arranged at the right center of the shielding body in a simulation mode, the neutron energy is thermal neutrons of 0.0253eV and intermediate energy neutrons of 100keV (the neutron yield accounts for 70%: 30%).

2) Model and material composition were calculated. A hollow spherical shield with an inner diameter of 0.5cm and an outer diameter of 2.5cm was built up, the shield was divided into 4 layers, each layer was 0.5cm thick, each layer contained the same ingredients, but the proportions of each mass component were different, as shown in the above example, see table 2.

TABLE 2 Mass constitution of Shielding Material Components of Point neutron Source (thermal and neutronic) models

3) Result analysis

2 kinds of energy neutrons generated by the point neutron source, 100keV neutrons and the 1 st layer shielding material interact, mainly scattering energy reduction reaction occurs, so that the number of low-energy neutrons is increased, and the total number of neutrons penetrating the 1 st layer is increased. The transmittance (the count without shield at the point of interest is defined as 1, the ratio of the count with shield to the count without shield) is greater than 1, see fig. 7. The neutron transmittance of the 2 nd, 3 rd and 4 th layers of shields is less than 1, which illustrates the shielding and protecting effects of the flexible radiation protection material, and is shown in figure 8.

The neutron flux 5cm after the neutrons passed through the composite shield plate consisting of 4 shields was calculated, see fig. 9. It can be seen that the relative intensity of thermal neutrons (0.0253eV) at 5cm is attenuated to 10-13 orders, the relative intensity of intermediate energy neutrons (100keV) is attenuated to 10-4 orders, and a good shielding protection effect is achieved.

4) And (6) evaluating the results. It can be seen from fig. 8 that the relative intensity distribution of neutrons which penetrate out of the aluminum alloy and are 5cm away from the source is the same as that of neutrons attenuated by doping aluminum alloy powder and tungsten-nickel alloy powder. However, the maximum value of the tungsten-nickel alloy material is higher than that of the aluminum alloy material, which shows that the shielding performance of the aluminum alloy doped material to neutrons is better than that of the tungsten-nickel alloy doped material.

Experimental example 3:

and evaluating a neutron-photon mixed radiation field. The shielding effect of 2 neutron flexible protective materials on photons is compared, and is shown in fig. 10 and fig. 11. It can be seen that the shielding body doped with the tungsten-nickel alloy has better shielding performance on photons than the aluminum alloy doped material.

Experimental example 4:

1) a neutron source item: in order to investigate the shielding and protecting performance of the material on fast neutrons. And introducing a fast neutron component into the neutron energy spectrum. According to the practical radiation field neutron energy spectrum, an isotropic point neutron source is arranged in the center of the shielding body in a simulation mode, the neutron energy is 0.0253eV thermal neutrons, 100keV intermediate energy neutrons and 1MeV fast neutrons (the neutron yield accounts for 60%: 30%: 10%).

2) The components and the proportion of the 4 layers of shielding body materials are changed, and the specific components are shown in Table 3.

TABLE 3 Shielding Material composition

The neutron spectrum at each interface after the neutron has passed through the shielding material is calculated and is shown in fig. 12.

TABLE 4 Back-neutron transmittance of the materials of the layers

^*The number of counts at the point of interest without shield is defined as 1, the ratio of the number of counts with shield to the number of counts without shield

For thermal neutrons, the flux drops to zero after passing through the 4 th layer of shielding material. For medium-energy neutrons, the 4 th layer back transmittance is 0.107, with the 4 shielding materials having the lowest attenuation ratios and the 2 nd layer having the highest attenuation ratios, indicating that the 1 st layer plays a key role in fast neutron moderation through inelastic scattering. The material also contains rare earth mineral powder (higher uranium and thorium nuclide), the neutron energy is reduced through inelastic scattering, and the material is a better fast neutron moderator. The material contains natural rubber with a high proportion, and the natural rubber contains a large amount of hydrogen, so that intermediate energy neutrons can be slowed down into thermal neutrons. Gadolinium and B are added into the 4 th layer material₄C, the thermal neutrons moderated by the 3-layer shield are absorbed as much as possible. The results in table 4 show that the fast neutron transmittance is reduced to 5% of the unshielded count, and the fast neutron protective material is a very effective fast neutron protective material, and the protection of the fast neutrons is superior to most market flexible neutron protective shielding materials.

Experimental example 5: mechanical property detection result of material

Compared with the products in the market, the material has better mechanical and mechanical properties which are slightly superior to the similar products.