A neutron shielding material for plugging and a method for preparing the same

Abstract

The application provides a neutron shielding material for plugging, which is prepared from raw materials comprising the following components: polyolefin elastomer: 5-95 parts by weight; boron carbide powder: 5-50 parts by weight; counterweight powder: 0.1-85 parts by weight; and surfactant: 0.1-2 parts by weight. Compared with the prior art, the neutron shielding material for plugging provided by the application realizes good interaction of the whole by using specific components with specific contents, and the neutron shielding material for plugging obtained by the application can have good plasticity when slightly heated below 100 DEG C (the most common operation is hot water soaking for 30 seconds), similar to plasticine, and the integrity of the material can be maintained during the plasticizing process, so that the material is convenient to operate, and the shape of the material can be fixed after cooling to exhibit an elastic material, and the function that cannot be realized by the existing plugging material can be realized.

Description

Technical Field

[0001] This invention relates to the field of materials for sealing, and more specifically, to a neutron shielding material for sealing and its preparation method. Background Technology

[0002] Currently, neutron-shielded buildings typically use sheet metal for neutron shielding of the roof, floor, and surrounding walls. However, gaps can easily form at the joints of the sheet metal shielding components, creating neutron hotspots and posing a safety hazard. Since these gaps vary in size and are irregular in shape, effectively filling them requires materials with a certain degree of flexibility and shapeability.

[0003] Currently, such applications typically use epoxy resin-based materials mixed with boron carbide powder and weighting powders such as iron and lead. While these materials can act as fillers and adhesives after curing, they are difficult to remove when structural adjustments are needed, causing significant inconvenience. Polypropylene-based materials and cross-linked ethylene-polyvinyl acetate copolymers are easy to remove, but they cannot be flexibly adjusted to fit different gap shapes, failing to achieve a tight seal.

[0004] In summary, the existing sealing materials have technical problems such as being unable to be shaped and being difficult to disassemble and remove. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a neutron shielding material for sealing and its preparation method. The neutron shielding material for sealing provided by the present invention can have good plasticity when slightly heated below 100°C (the most common operation is immersion in hot water for 30 seconds), similar to clay. At the same time, the material can maintain its integrity during the molding process, making it easy to handle. After cooling, the shape can be fixed and it can exhibit the properties of an elastic material, which can achieve functions that existing sealing materials cannot.

[0006] This invention provides a neutron shielding material for sealing, prepared from raw materials comprising the following components:

[0007] Polyolefin elastomer: 5-95 parts by weight;

[0008] Boron carbide powder: 5-50 parts by weight;

[0009] Counterweight powder: 0.1–85 parts by weight;

[0010] Surfactant: 0.1 to 2 parts by weight.

[0011] Preferably, the polyolefin elastomer is selected from vinyl polyolefin elastomers and / or propylene polyolefin elastomers.

[0012] Preferably, the polyolefin elastomer is composed of polyolefin elastomer A and polyolefin elastomer B;

[0013] The melt index of the polyolefin elastomer A is 0.5 to 2 g / 10 min; the melt index of the polyolefin elastomer B is greater than 3 g / 10 min.

[0014] Preferably, the boron carbide powder has a particle size of 100 mesh to 500 mesh.

[0015] Preferably, the counterweight powder is selected from one or more of iron powder, steel powder, tungsten powder, and lead powder.

[0016] Preferably, the surfactant is selected from anionic surfactants and / or nonionic surfactants.

[0017] The present invention also provides a method for preparing the neutron shielding material for blocking described in the above technical solution, comprising the following steps:

[0018] Boron carbide powder and surfactant are dispersed evenly in the presence of solvent. After the solvent is dried, the resulting mixed powder is then kneaded with counterweight powder and polyolefin elastomer. After molding, a neutron shielding material for sealing is obtained.

[0019] Preferably, the dispersion method is ball milling or high-speed stirring; the dispersion speed is 200 rpm to 400 rpm, and the time is 1 h to 3 h;

[0020] The drying solvent is dried at a temperature of 80℃ to 120℃ for 8 hours to 10 hours.

[0021] Preferably, the mixing method in step b) is intensive mixing or open mixing; the mixing temperature is 80℃~120℃ and the time is 5min~20min.

[0022] Preferably, the molding method in step b) is direct molding or compression molding; the molding temperature is 100℃~120℃, the pressure is 2MPa~10MPa, and the time is 300s~600s.

[0023] This invention provides a neutron shielding material for sealing, prepared from raw materials comprising the following components: polyolefin elastomer: 5-95 parts by weight; boron carbide powder: 5-50 parts by weight; weighting powder: 0.1-85 parts by weight; surfactant: 0.1-2 parts by weight. Compared with the prior art, the neutron shielding material for sealing provided by this invention, using specific components in specific amounts, achieves better overall interaction. The resulting neutron shielding material for sealing exhibits good plasticity, similar to modeling clay, when slightly heated below 100°C (the most common operation is immersion in hot water for 30 seconds). Simultaneously, it maintains the integrity of the material during the shaping process, facilitating handling. Furthermore, after cooling, its shape is fixed, exhibiting elasticity, thus achieving functions that existing sealing materials cannot.

[0024] In addition, the preparation method provided by this invention is simple, mild and easy to control, and has broad application prospects. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] This invention provides a neutron shielding material for sealing, prepared from raw materials comprising the following components:

[0027] Polyolefin elastomer: 5-95 parts by weight;

[0028] Boron carbide powder: 5-50 parts by weight;

[0029] Counterweight powder: 0.1–85 parts by weight;

[0030] Surfactant: 0.1 to 2 parts by weight.

[0031] This invention provides a sealing material with neutron shielding capability and free shapeability; it is prepared from raw materials including polyolefin elastomer, boron carbide powder, weight powder and surfactant, preferably prepared from polyolefin elastomer, boron carbide powder, weight powder and surfactant.

[0032] In this invention, the polyolefin elastomer is preferably selected from vinyl polyolefin elastomers (comonomers of 4-8 carbon α-olefins, POE, such as Dow's Engage, Exxon's EXACT, Sabic's FORTIFY, etc.) and / or propylene-based polyolefin elastomers (comonomers of ethylene, such as Dow's Versify, Exxon's Vistamaxx, Sabic's Cohere, etc.). This invention does not impose any special restrictions on the source of the polyolefin elastomer; commercially available products well-known to those skilled in the art can be used.

[0033] In this invention, the polyolefin elastomer is preferably composed of two or more of the above-mentioned components, and more preferably composed of polyolefin elastomer A and polyolefin elastomer B.

[0034] In this invention, the melt index of the polyolefin elastomer A is preferably 0.5–2 g / 10 min; the melt index of the polyolefin elastomer B is preferably greater than 3 g / 10 min. This invention uses a combination of polyolefin elastomers with different melt indices as the base material, ensuring that the material is malleable while also maintaining its integrity through a partially non-melting skeleton.

[0035] In this invention, the neutron shielding material for sealing comprises 5 to 95 parts by weight of polyolefin elastomer, preferably 15 to 65 parts by weight.

[0036] In this invention, the particle size of the boron carbide powder is preferably 100 mesh to 500 mesh, more preferably 200 mesh to 300 mesh. This invention does not impose any special restrictions on the source of the boron carbide powder; commercially available products well-known to those skilled in the art can be used.

[0037] In this invention, the neutron shielding material for sealing comprises 5 to 50 parts by weight of boron carbide powder, preferably 5 to 10 parts by weight.

[0038] In this invention, the counterweight powder is preferably selected from one or more of iron powder, steel powder, tungsten powder, and lead powder, and more preferably from iron powder or lead powder. This invention does not impose any special restrictions on the source of the counterweight powder; commercially available products well-known to those skilled in the art can be used.

[0039] In this invention, the neutron shielding material for sealing comprises 0.1 to 85 parts by weight of counterweight powder, preferably 30 to 80 parts by weight.

[0040] In this invention, the surfactant is preferably selected from anionic surfactants and / or nonionic surfactants, more preferably nonionic surfactants, specifically including silane coupling agents, polyvinyl alcohol (PVA), and stearic acid surfactants (such as sodium stearate); the anionic surfactant is specifically such as octylphosphonate and dodecylphosphonate. This invention does not impose any special restrictions on the source of the surfactant; commercially available products well known to those skilled in the art can be used.

[0041] In this invention, the neutron shielding material for sealing includes 0.1 to 2 parts by weight of surfactant, preferably 0.1 to 0.5 parts by weight.

[0042] The neutron shielding material for sealing provided by this invention uses specific components in specific amounts to achieve good overall interaction. The resulting neutron shielding material for sealing can have good plasticity when slightly heated below 100°C (the most common operation is immersion in hot water for 30 seconds), similar to clay. At the same time, it can maintain the integrity of the material during the shaping process, making it easy to handle. After cooling, the shape can be fixed and it can exhibit the properties of an elastic material, which can achieve functions that existing sealing materials cannot.

[0043] The present invention also provides a method for preparing the neutron shielding material for blocking described in the above technical solution, comprising the following steps:

[0044] Boron carbide powder and surfactant are dispersed evenly in the presence of solvent. After the solvent is dried, the resulting mixed powder is then kneaded with counterweight powder and polyolefin elastomer. After molding, a neutron shielding material for sealing is obtained.

[0045] In this invention, the boron carbide powder, surfactant, weighting powder, and polyolefin elastomer are the same as those in the above technical solutions, and will not be repeated here.

[0046] In this invention, the solvent is preferably alcohol or water; the amount of solvent used is preferably 20 ml to 80 ml per 100 g boron carbide powder, more preferably 50 ml per 100 g boron carbide powder.

[0047] In this invention, the dispersion process is preferably specifically as follows:

[0048] After mixing boron carbide powder with a surfactant, it is diluted with a solvent and then dispersed. The dispersion method is preferably ball milling or high-speed stirring. The dispersion speed is preferably 200 rpm to 400 rpm, and the dispersion time is preferably 1 h to 3 h. The ball milling speed is preferably 300 r / min, and the stirring time is 1 h. The high-speed stirring speed is preferably 300 r / min, and the stirring time is 2 h. This allows the boron carbide powder and the surfactant to be fully stirred, broken, and dispersed.

[0049] In this invention, the temperature of the drying solvent is preferably 80℃~120℃, more preferably 80℃, and the time is preferably 8h~10h, more preferably 8h.

[0050] In this invention, the mixing method is preferably intensive mixing or open mixing; the mixing temperature is preferably 80℃~120℃, more preferably 120℃, and the mixing time is preferably 5min~20min, more preferably 10min.

[0051] In this invention, the forming method is preferably direct forming or compression molding; the forming temperature is preferably 100℃~120℃, the pressure is preferably 2MPa~10MPa, and the time is preferably 300s~600s; wherein, direct forming means directly producing sheets after open mixing, with a preferred temperature of 120℃, a preferred pressure of 5MPa, and a preferred time of 300s; compression molding means taking out the sheet after internal mixing and sending it to a forming mold for hot pressing to form a sheet, with a preferred temperature of 120℃, a preferred pressure of 5MPa, and a preferred time of 450s.

[0052] The preparation method provided by this invention is simple, mild, and easy to control, and has broad application prospects.

[0053] This invention provides a neutron shielding material for sealing, prepared from raw materials comprising the following components: polyolefin elastomer: 5-95 parts by weight; boron carbide powder: 5-50 parts by weight; weighting powder: 0.1-85 parts by weight; surfactant: 0.1-2 parts by weight. Compared with the prior art, the neutron shielding material for sealing provided by this invention, using specific components in specific amounts, achieves better overall interaction. The resulting neutron shielding material for sealing exhibits good plasticity, similar to modeling clay, when slightly heated below 100°C (the most common operation is immersion in hot water for 30 seconds). Simultaneously, it maintains the integrity of the material during the shaping process, facilitating handling. Furthermore, after cooling, its shape is fixed, exhibiting elasticity, thus achieving functions that existing sealing materials cannot.

[0054] In addition, the preparation method provided by this invention is simple, mild and easy to control, and has broad application prospects.

[0055] To further illustrate the present invention, the following embodiments are provided for detailed description. All raw materials used in the following embodiments of the present invention are commercially available; wherein, the boron carbide powder has a particle size of 200 mesh to 300 mesh.

[0056] Example 1

[0057] (1) Formula (by weight):

[0058] Polyolefin elastomer A (Vistamaxx 6102): 16 parts;

[0059] Polyolefin elastomer B (Versify 4301): 49 parts;

[0060] Boron carbide powder: 5 parts;

[0061] Weighting powder (iron powder): 30 parts;

[0062] Surfactant (polydimethylsiloxane): 0.1 parts.

[0063] (2) Preparation method:

[0064] Prepare all the ingredients according to the above formula;

[0065] First, boron carbide powder is mixed with a surfactant, and then alcohol is added as a medium at a ratio of 50 ml / 100 g. The mixture is ball-milled at 300 rpm for 1 hour to ensure that the boron carbide powder and surfactant are fully stirred, crushed, and dispersed. Then, the resulting mixed powder is dried at 80°C for 8 hours, weighed, and then mixed with counterweight powder and substrate (polyolefin elastomer A and polyolefin elastomer B) at 120°C for 10 minutes. The roller spacing is adjusted to 1 cm, and the mixture is directly formed (temperature 120°C, pressure 5 MPa, time 300 seconds) to obtain a 1 cm thick sheet, which is the neutron shielding material for sealing.

[0066] Example 2

[0067] (1) Formula (by weight):

[0068] Polyolefin elastomer A (Engage8540): 2 parts;

[0069] Polyolefin elastomer B (FORTIFY1055D): 13 parts;

[0070] Boron carbide powder: 5 parts;

[0071] Weighting powder (lead powder): 80 parts;

[0072] Surfactant (sodium stearate): 0.1 parts.

[0073] (2) Preparation method:

[0074] Prepare all the ingredients according to the above formula;

[0075] First, boron carbide powder is mixed with a surfactant, and then alcohol is added as a medium at a ratio of 50 ml / 100 g. The mixture is ball-milled at 300 rpm for 1 hour to ensure that the boron carbide powder and surfactant are fully stirred, crushed, and dispersed. Then, the resulting mixed powder is dried at 80°C for 8 hours, weighed, and then mixed with counterweight powder and substrate (polyolefin elastomer A and polyolefin elastomer B) at 120°C for 10 minutes. The mixture is then placed into a 1 cm thick mold and molded at 120°C and 5 MPa for 450 seconds to obtain a 1 cm thick sheet, which is the neutron shielding material for sealing.

[0076] Comparative Example 1

[0077] (1) Formula (by weight):

[0078] Polyolefin elastomer A (Vistamaxx 6102): 65 parts;

[0079] Boron carbide powder: 5 parts;

[0080] Weighting powder (iron powder): 30 parts;

[0081] Surfactant (polydimethylsiloxane): 0.1 parts.

[0082] (2) Preparation method:

[0083] Prepare all the ingredients according to the above formula;

[0084] First, boron carbide powder is mixed with a surfactant, and then alcohol is added as a medium at a ratio of 50 ml / 100 g. The mixture is ball-milled at 300 rpm for 1 hour to ensure that the boron carbide powder and surfactant are fully stirred, crushed, and dispersed. Then, the resulting mixed powder is dried at 80°C for 8 hours, weighed, and then mixed with counterweight powder and substrate (polyolefin elastomer A) at 120°C for 10 minutes. The roller spacing is adjusted to 1 cm, and the mixture is directly molded into a 1 cm thick sheet, which is the neutron shielding material for sealing.

[0085] Comparative Example 2

[0086] Polyolefin elastomer B (Versify 4301): 65 parts;

[0087] Boron carbide powder: 5 parts;

[0088] Weighting powder (iron powder): 30 parts;

[0089] Surfactant (polydimethylsiloxane): 0.1 parts.

[0090] (2) Preparation method:

[0091] Prepare all the ingredients according to the above formula;

[0092] First, boron carbide powder is mixed with a surfactant, and then alcohol is added as a medium at a ratio of 50 ml / 100 g. The mixture is then ball-milled at 300 rpm for 1 hour to ensure that the boron carbide powder and surfactant are fully stirred, crushed, and dispersed. The resulting mixed powder is then dried at 80°C for 8 hours, weighed, and then mixed with counterweight powder and substrate (polyolefin elastomer B) at 120°C for 10 minutes. The roller spacing is adjusted to 1 cm, and the mixture is directly molded into a 1 cm thick sheet, which is the neutron shielding material for sealing.

[0093] Various performance tests were conducted on the neutron shielding materials for sealing provided in the above embodiments and comparative examples. Among them, after soaking in boiling water for 30 seconds, it was tested whether the shape could be changed by manual operation; the results are shown in Table 1.

[0094] Table 1. Performance results of the neutron shielding materials for containment provided in the examples and comparative examples.

[0095]

[0096] Note: All transmittance is below 10^-7, which means there is no radiation measurement by default.

[0097] In summary, this invention uses a specific polyolefin elastomer substrate, fills it with boron carbide powder and counterweight powder, and combines it with a surfactant to achieve good overall interaction, resulting in a malleable neutron shielding material for sealing that can be freely shaped by micro-heating. This material can be freely kneaded into shape during use, and due to its inherent elasticity, it ensures a full fit with the gap; at the same time, it can be easily removed by simply reshaping it with micro-heating.

[0098] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A neutron shielding material for sealing, characterized in that, It is prepared from raw materials including the following components: Polyolefin elastomer: 5~95 parts by weight; Boron carbide powder: 5~50 parts by weight; Weighting powder: 0.1~85 parts by weight; Surfactant: 0.1~2 parts by weight; The polyolefin elastomer is selected from vinyl polyolefin elastomers and / or propylene-based polyolefin elastomers; The polyolefin elastomer is composed of polyolefin elastomer A and polyolefin elastomer B; The melt index of the polyolefin elastomer A is 0.5~2 g / 10 min; the melt index of the polyolefin elastomer B is greater than 3 g / 10 min.

2. The neutron shielding material for sealing according to claim 1, characterized in that, The boron carbide powder has a particle size of 100 mesh to 500 mesh.

3. The neutron shielding material for sealing according to claim 1, characterized in that, The counterweight powder is selected from one or more of iron powder, steel powder, tungsten powder, and lead powder.

4. The neutron shielding material for sealing according to claim 1, characterized in that, The surfactant is selected from anionic surfactants and / or nonionic surfactants.

5. A method for preparing a neutron shielding material for blocking according to any one of claims 1 to 4, characterized in that, Includes the following steps: Boron carbide powder and surfactant are dispersed evenly in the presence of solvent. After the solvent is dried, the resulting mixed powder is then kneaded with counterweight powder and polyolefin elastomer. After molding, a neutron shielding material for sealing is obtained.

6. The preparation method according to claim 5, characterized in that, The dispersion method is ball milling or high-speed stirring; the dispersion speed is 200 rpm to 400 rpm, and the time is 1 h to 3 h. The drying solvent is dried at a temperature of 80℃ to 120℃ for 8 hours to 10 hours.

7. The preparation method according to claim 5, characterized in that, The mixing method is either intensive mixing or open mixing; the mixing temperature is 80℃~120℃, and the time is 5min~20min.

8. The preparation method according to claim 5, characterized in that, The molding method is direct molding or compression molding; the molding temperature is 100℃~120℃, the pressure is 2MPa~10MPa, and the time is 300s~600s.

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