A radiation shielding composite material and a method of manufacturing the same

Abstract

The present application provides a kind of ray shielding composite material, including first high polymer base shielding layer, metal layer being combined in the first high polymer base shielding layer and second high polymer base shielding layer being combined in the surface of the metal layer;The first high polymer base shielding layer and the second high polymer base shielding layer include matrix resin, and the density of the matrix resin is less than 1.0g / cm 3 , 125 ℃ melt index is 12-22 g / 10 min. The present application also provides a preparation method of ray shielding composite material. The ray shielding composite material provided by the present application has a three-layer structure, and can achieve high protection efficiency and light weight with less shielding material dosage or smaller overall thickness. The resin matrix has low density, and can be processed at 100-120 ℃, effectively avoiding the sintering and agglomeration of lead powder and other materials under high temperature.

Description

Technical Field

[0001] This invention relates to the field of radiation protection, and more particularly to a radiation shielding composite material and its preparation method. Background Technology

[0002] X-rays and gamma rays play a crucial role in medical testing, diagnosis, treatment, and industrial flaw detection. Currently, the best radiation shielding material worldwide remains lead-based (MAVIG, Germany), but materials using lead as the shielding source are typically bulky. Furthermore, elements such as lead and bismuth exhibit weak absorption in the 40–80 keV range, resulting in poor shielding effectiveness in the low-energy radiation region. This issue can be addressed by incorporating rare-earth elements with relatively low absorption edges in the K-layer.

[0003] In fact, the dispersion and distribution of protective particles in the matrix directly affect the protective performance of the material. Introducing multi-layered overlapping and dense metal layers can increase the interactions between particles and radiation, such as Compton scattering, thus achieving high protective efficiency with a relatively small weight. However, the bonding force between the metal coating and the resin is generally weak, and exposed materials are prone to damage and failure due to dragging and friction. Furthermore, fillers such as lead powder can sinter into lumps during high-temperature mixing, resulting in large-area aggregation that cannot be dispersed. Therefore, providing a radiation shielding material with good protective effect and without agglomeration is of great significance. Summary of the Invention

[0004] The technical problem solved by this invention is to provide a radiation shielding composite material. The radiation shielding composite material provided by this application has the advantages of being lightweight and having good protective effect, and solves the problem of high-temperature sintering and agglomeration of fillers such as lead powder.

[0005] In view of this, this application provides a radiation shielding composite material, including a first polymer-based shielding layer, a metal layer composited on the first polymer-based shielding layer, and a second polymer-based shielding layer composited on the surface of the metal layer;

[0006] The first and second polymer-based shielding layers comprise a matrix resin, wherein the density of the matrix resin is less than 1.0 g / cm³. 3 The melt index at 125℃ is 12-22 g / 10 min.

[0007] Preferably, the first polymer-based shielding layer and the second polymer-based shielding layer further include a shielding material and a dispersant; the contents of the matrix resin, the shielding material and the dispersant in the first polymer-based shielding layer and the second polymer-based shielding layer are independently 5-30 parts by weight, 100 parts by weight and 1-5 parts by weight, respectively.

[0008] Preferably, the matrix resin is selected from one or more of low-density polyethylene, ethylene-octene copolymer, ethylene-propylene copolymer, and ethylene-vinyl acetate copolymer.

[0009] Preferably, the shielding material comprises 60 to 98 parts by weight of one or more of lead, tungsten, and tantalum, and 2 to 40 parts by weight of one or more of cerium oxide, gadolinium oxide, samarium oxide, and erbium oxide.

[0010] Preferably, the metal in the metal layer is selected from one or more of gold, tungsten, and tantalum.

[0011] Preferably, the thickness of the first polymer-based shielding layer is 0.1–10 mm, the thickness of the metal layer is 0.1–2 μm, and the thickness of the second polymer-based shielding layer is 0.1–10 mm.

[0012] This application also provides a method for preparing the aforementioned radiation shielding composite material, comprising the following steps:

[0013] The first polymer-based shielding layer is placed in the magnetron sputtering cavity for metal sputtering to obtain a metal coating.

[0014] A second polymer-based shielding layer is coated onto the surface of the metal coating, and then hot-pressed to obtain a radiation shielding composite material.

[0015] Preferably, the preparation method of the first polymer-based shielding layer and the second polymer-based shielding layer is as follows:

[0016] The matrix resin, shielding powder, and dispersant are added to a twin-screw extruder and mixed and extruded at 100–150°C.

[0017] Preferably, the gas pressure inside the magnetron sputtering cavity is 2 to 5 × 10⁻⁶. -3 Pa, the metal sputtering time is 2 to 10 hours.

[0018] Preferably, the hot pressing temperature is 50–150°C, the pressure is 0.2–0.5 MPa, and the time is 5–10 s.

[0019] This application provides a radiation shielding composite material, comprising a first polymer-based shielding layer, a metal layer, and a second polymer-based shielding layer sequentially laminated together, wherein the density of the first polymer-based shielding layer and the second polymer-based shielding layer is less than 1.0 g / cm³. 3The melt index at 125℃ is 12-22 g / 10min. The radiation shielding composite material provided in this application limits the density and melt index of the matrix resin in the polymer-based shielding layer, allowing it to be mixed and processed at 100-120℃. This not only solves the problem of high-temperature sintering and agglomeration of shielding materials such as lead powder, but also reduces the specific gravity of the radiation shielding composite material, reduces the use of additives and vulcanization processes, and achieves energy saving and environmental protection to a certain extent. Furthermore, the radiation shielding composite material provided in this application uses a three-layer structure with the metal layer in the middle and the polymer-based shielding layers on both sides as protective shells, which can effectively prevent damage to the metal layer caused by external friction and dragging, and solve the problem of poor adhesion between the metal coating and the resin layer. Attached Figure Description

[0020] Figure 1 A schematic diagram of the structure of the X-ray shielding composite material provided by the present invention;

[0021] Figure 2 This is a macroscopic schematic diagram of the polymer-based shielding layer compound prepared in Example 1 and Comparative Example 2 of the present invention. Detailed Implementation

[0022] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0023] In view of the problem of agglomeration of fillers during the mixing process in the prior art, this application provides a radiation shielding composite material, which solves the problem of high-temperature sintering and agglomeration of fillers such as lead powder by using a matrix resin with a specific density and melt index, and can also reduce the specific gravity of the material; specifically, the present invention discloses a radiation shielding composite material, including a first polymer base shielding layer, a metal layer composited on the first polymer base shielding layer, and a second polymer base shielding layer composited on the surface of the metal layer;

[0024] The first and second polymer-based shielding layers comprise a matrix resin, wherein the density of the matrix resin is less than 1.0 g / cm³. 3 The melt index at 125℃ is 12-22 g / 10 min.

[0025] The radiation shielding composite material includes a first polymer-based shielding layer, a metal layer, and a second polymer-based shielding layer; wherein the materials of the first polymer-based shielding layer and the second polymer-based shielding layer can be the same or different, and this application does not have any particular restrictions on this.

[0026] Taking the first polymer shielding layer as an example, the first polymer-based shielding layer includes a matrix resin, a shielding material, and a dispersant. The matrix resin is selected from one or more of low-density polyethylene, ethylene-octene copolymer, ethylene-propylene copolymer, and ethylene-vinyl acetate copolymer, and the density of the matrix resin is less than 1.0 g / cm³. 3 The melt flow index at 125℃ is 12–22 g / 10 min; specifically, the density of the matrix resin is 0.80–0.95 g / cm³. 3 The melt flow index at 125℃ is 18-22 g / 10min. The selection of the matrix resin with the above characteristics lowers the processing temperature, effectively solving the problem of agglomeration and clumping of lead powder, bismuth powder, etc., during high-temperature processing. The matrix resin can be a commercially available product or prepared according to conventional methods in the art. The shielding material includes 60-98 parts by weight of one or more of lead, tungsten, and tantalum, and 2-40 parts by weight of one or more of cerium oxide, gadolinium oxide, samarium oxide, and erbium oxide; that is, in this application, the shielding material simultaneously includes metallic materials and metal oxide materials; specifically, the shielding material includes 60-90 parts by weight of one or more of lead, tungsten, and tantalum, and 10-40 parts by weight of one or more of cerium oxide, gadolinium oxide, samarium oxide, and erbium oxide. For the shielding material described in this application, the more metallic materials with higher atomic numbers, the better the shielding effect. Metal oxides are used to compensate for the weak absorption region of the material in the 40-88 kV range, resulting in higher radiation protection efficiency under low-energy conditions. The dispersant is a dispersant well known to those skilled in the art, and can be selected from anionic dispersants or cationic dispersants; this application does not impose any particular limitation on this. The first polymer-based shielding layer comprises 5-30 parts by weight of a matrix resin, 100 parts by weight of a shielding material, and 1-5 parts by weight of a dispersant; specifically, the matrix resin comprises 10-20 parts by weight, the shielding material comprises 100 parts by weight, and the dispersant comprises 2-4 parts by weight.

[0027] The specific description of the material in the second polymer-based shielding layer of this application is the same as that of the material in the first polymer-based shielding layer, and will not be repeated here.

[0028] According to the present invention, the metal layer between the first polymer-based shielding layer and the second polymer-based shielding layer can improve the radiation protection effect. The thickness of the first polymer-based shielding layer is 0.1-10 mm, the thickness of the metal layer is 0.1-2 μm, and the thickness of the second polymer-based shielding layer is 0.1-10 mm. Although the thickness of the metal layer is low, its introduction improves the radiation protection effect while reducing the proportion of radiation shielding composite material.

[0029] This application also provides a method for preparing the above-mentioned radiation shielding composite material, including the following steps:

[0030] The first polymer-based shielding layer is placed in the magnetron sputtering cavity for metal sputtering to obtain a metal coating.

[0031] A second polymer-based shielding layer is coated onto the surface of the metal coating, and then hot-pressed to obtain a radiation shielding composite material.

[0032] The preparation method provided in this application first prepares a first polymer-based shielding layer and a second polymer-based shielding layer. Even if the materials used for the first and second polymer-based shielding layers are different, the preparation process remains the same. The specific preparation methods for the first and second polymer-based shielding layers are as follows:

[0033] The matrix resin, shielding powder, and dispersant are added to a twin-screw extruder and mixed and extruded at 100–150°C; more specifically, they are mixed at 100–120°C.

[0034] After the above-mentioned polymer-based shielding layer is prepared, the first polymer-based shielding layer is placed in a magnetron sputtering cavity for metal sputtering to obtain a metal coating. During this process, the gas pressure in the magnetron sputtering cavity is 2 to 5 × 10⁻⁶. -3 The metal sputtering time is 2–10 h; specifically, the gas pressure is 2–3 × 10 Pa. -3 Pa, the metal sputtering time is 3 to 8 hours.

[0035] Finally, this application covers the surface of the metal coating with a second polymer-based shielding layer, followed by hot-pressing to obtain a radiation shielding composite material. During this process, the hot-pressing temperature is 50–150°C, the pressure is 0.2–0.5 MPa, and the time is 5–10 s; specifically, the hot-pressing temperature is 60–100°C, the pressure is 0.3–0.5 MPa, and the time is 6–10 s.

[0036] The radiation shielding composite material provided by this invention has a three-layer structure, which can achieve high protection efficiency and lightweight with less shielding material or smaller overall thickness; the selected resin matrix has low density and can be processed at 100-120℃, which can effectively avoid the problem of sintering and agglomeration of lead powder and other materials under high temperature.

[0037] To further understand the present invention, the radiation shielding composite material provided by the present invention will be described in detail below with reference to the embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0038] The protective efficiency of the composite material was determined according to GBZT147-2002.

[0039] Example 1

[0040] In this embodiment, a radiation shielding composite material includes a low-density polyethylene-based shielding layer / tungsten-plated layer / low-density polyethylene-based shielding layer arranged sequentially, as shown in the specific structure. Figure 1 As shown, Figure 1 1 is a low-density polyethylene-based shielding layer, 2 is a tungsten layer, and 3 is a low-density polyethylene-based shielding layer.

[0041] The low-density polyethylene shielding layer contains 5 parts with a density of 0.92 g / cm³. 3 Low-density polyethylene with a melt index of 16 g / 10 min at 125°C; 80 parts lead powder; 20 parts gadolinium oxide and 5 parts sodium dodecylbenzenesulfonate, an anionic dispersant.

[0042] The thickness of both low-density polyethylene-based shielding layers is 0.1 mm; the thickness of the tungsten-plated layer is 0.2 μm.

[0043] The specific preparation steps are as follows:

[0044] A) Mix the polymer-based shielding raw materials macroscopically and evenly according to the above ratio in advance, then add them to a twin-screw extruder and extrude them at 100°C to obtain a low-density polyethylene-based shielding sheet with a thickness of 0.1 mm.

[0045] b. Place the low-density polyethylene shielding sheet in a magnetron sputtering furnace, using a tungsten target, and sputter at 2×10⁻⁶ rpm. -3 Under Pa, sputtering for 2 hours yielded a tungsten-coated polymer shielding sheet;

[0046] c. Using a heat sealing machine at 60℃ and 0.3MPa pressure, a low-density polyethylene shielding sheet is combined with a tungsten-plated shielding sheet to obtain a radiation shielding composite material.

[0047] A low-density polyethylene-based shielding material without a metal coating was prepared as Comparative Example 1, with a total thickness of 0.2 mm, and other aspects were the same as in Example 1.

[0048] With a density of 1.03 g / cm³ 3 The polyethylene with a melt index of 10 g / 10 min at 150°C was used as a control matrix and was compounded at 160°C. Other steps were the same as in Example 1 to obtain a polyethylene shielding compound, which served as Comparative Example 2.

[0049] Macroscopic diagram of the compound as follows Figure 2 As shown, the left side is the appearance of the compound of Comparative Example 2, and the right side is the appearance of the compound of Example 1. In Comparative Example 2, there is obvious lead powder agglomeration and sintering; while the compound of Example 1 has a uniform appearance and no obvious shiny crystal points. This indicates that resin with a high melt index at the same temperature is more suitable as the matrix of the shielding material.

[0050] Examples 2-4

[0051] The difference from Example 1 is that in Examples 2 to 4, the polymer-based shielding layer of a radiation shielding composite material is ethylene-octene copolymer, ethylene-propylene copolymer, and ethylene-vinyl acetate copolymer, respectively.

[0052] The densities of the ethylene-octene copolymer, ethylene-propylene copolymer, and ethylene-vinyl acetate copolymer used were 0.89 g / cm³. 3 0.85g / cm 3 0.94g / cm 3 The melt flow rates at 125℃ were 18 g / 10 min, 22 g / 10 min, and 20 g / 10 min, respectively.

[0053] The mixing temperatures were 120℃, 110℃, and 105℃, respectively.

[0054] Examples 5-7

[0055] The difference from Example 1 is that in Examples 5 to 7, the structure of a radiation shielding composite material is low-density polyethylene / tungsten-plated layer / ethylene-octene copolymer, ethylene-octene copolymer / tungsten-plated layer / ethylene-propylene copolymer, and ethylene-octene copolymer / tungsten-plated layer / ethylene-vinyl acetate copolymer, respectively.

[0056] The protective efficiency of the test examples and comparative examples against different rays is shown in Table 1.

[0057] Table 1 shows the shielding efficiency values ​​of the shielding materials prepared in Examples 1-7 against different types of radiation.

[0058]

[0059]

[0060] As can be seen from Table 1, the introduction of a tungsten coating layer with a thickness of only 0.2 μm significantly improves the shielding effectiveness, and the shielding performance of the material is not significantly related to the selected polymer matrix.

[0061] Examples 8-10

[0062] The difference from Example 1 is that in Examples 8 to 10, the thickness of the tungsten coating was 0.5 μm, 1.0 μm, 1.5 μm and 2.0 μm, respectively; and the deposition time was 3 h, 5 h, 8 h and 10 h, respectively.

[0063] Examples 11-13

[0064] The difference from Example 8 is that in Examples 11 to 13, the thickness of the low-density polyethylene layer is 0.3 mm, 0.5 mm, and 1.0 mm, respectively.

[0065] The protection efficiency of the above embodiments against different types of radiation was tested, and the results are shown in Table 2.

[0066] Table 2 shows the shielding efficiency values ​​of the shielding materials prepared in Examples 8-13 against different types of radiation.

[0067]

[0068]

[0069] As shown in Table 2, when the thickness of the polymer shielding layer is the same, the shielding efficiency increases with the increase of the thickness of the tungsten plating layer; when the thickness of the tungsten plating layer is the same, the shielding efficiency increases with the increase of the thickness of the polymer shielding layer.

[0070] Examples 14-15

[0071] The difference from Example 11 is that in Examples 14 and 15, the metal plating layers are gold plating and tantalum plating, respectively.

[0072] The protection efficiency of the above embodiments against different rays was tested, and the test results are shown in Table 3.

[0073] Table 3 shows the shielding efficiency values ​​of the shielding materials prepared in Examples 14-15 against different types of radiation.

[0074]

[0075] As can be seen from Table 3, the gold plating layer has the best effect, while the effects of tantalum plating and tungsten plating are not much different.

[0076] Examples 16-19

[0077] The difference from Example 11 is that the powder in the polymer-based shielding layer of the shielding material in Examples 16 to 19 includes 70 parts lead powder and 30 parts gadolinium oxide; 60 parts lead powder and 40 parts gadolinium oxide; 90 parts lead powder and 10 parts gadolinium oxide; and 100 parts lead powder, respectively.

[0078] Examples 20-24

[0079] The difference from Example 11 is that in Examples 20 to 24, the rare earth oxide powders in the polymer-based shielding layer are respectively cerium oxide, erbium oxide, samarium oxide, a mixture of samarium oxide and gadolinium oxide, a mixture of erbium oxide and cerium oxide, 10 parts of cerium oxide, 10 parts of erbium oxide, 10 parts of samarium oxide, a mixture of 5 parts of samarium oxide and 5 parts of gadolinium oxide, a mixture of 5 parts of erbium oxide and 5 parts of cerium oxide, and 90 parts of lead powder.

[0080] Examples 25-30

[0081] The difference from Example 18 is that the shielding metal powder in the polymer-based shielding layer in Examples 25 to 30 is tungsten powder, tantalum powder, bismuth powder, a mixture of bismuth powder and lead powder (1:1), a mixture of tungsten powder and lead powder (1:1), and a mixture of bismuth powder and tantalum powder (1:1), respectively.

[0082] The protection efficiency of the above embodiments against different rays was tested, and the test results are shown in Table 4.

[0083] Table 4 shows the shielding efficiency values ​​of the shielding materials prepared in Examples 16-30 against different types of radiation.

[0084]

[0085]

[0086] As can be seen from Table 4, different combinations of shielding powders result in different shielding efficiencies for radiation. The higher the content of elements with larger atomic numbers, the better the shielding effect in the high-energy region; the higher the content of rare earth oxides, the better the protection performance in the low-energy region.

[0087] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0088] 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 radiation shielding composite material, comprising a first polymer-based shielding layer, a metal layer composited with the first polymer-based shielding layer, and a second polymer-based shielding layer composited on the surface of the metal layer; The first polymer-based shielding layer and the second polymer-based shielding layer contain 5 parts of material with a density of 0.92 g / cm³. 3 Low-density polyethylene with a melt index of 16 g / 10 min at 125°C; The first polymer-based shielding layer and the second polymer-based shielding layer further include a shielding material and a dispersant; the shielding material includes a mixture of 90 parts by weight of lead powder and 10 parts by weight of gadolinium oxide, or a mixture of 90 parts by weight of lead powder and 10 parts by weight of cerium oxide, or a mixture of 90 parts by weight of lead powder and 10 parts by weight of erbium oxide, or a mixture of 90 parts by weight of lead powder, 5 parts by weight of samarium oxide and 5 parts by weight of gadolinium oxide, or a mixture of 90 parts by weight of lead powder, 5 parts by weight of erbium oxide and 5 parts by weight of cerium oxide, or a mixture of 90 parts by weight of tantalum powder and 10 parts by weight of gadolinium oxide, or a mixture of 45 parts by weight of bismuth powder, 45 parts by weight of lead powder and 10 parts by weight of gadolinium oxide powder, or a mixture of 45 parts by weight of bismuth powder, 45 parts by weight of tantalum powder and 10 parts by weight of gadolinium oxide powder; The metal in the metal layer is selected from tungsten; The method for preparing the radiation shielding composite material includes the following steps: The first polymer-based shielding layer is placed in the magnetron sputtering cavity for metal sputtering to obtain a metal coating. A second polymer-based shielding layer is coated onto the surface of the metal coating, and then hot-pressed to obtain a radiation shielding composite material. The specific methods for preparing the first polymer-based shielding layer and the second polymer-based shielding layer are as follows: The matrix resin, shielding powder, and dispersant are added to a twin-screw extruder and mixed and extruded at 100~120℃.

2. The radiation shielding composite material according to claim 1, characterized in that, The thickness of the first polymer-based shielding layer is 0.1~10mm, the thickness of the metal layer is 0.1~2μm, and the thickness of the second polymer-based shielding layer is 0.1~10mm.

3. The method for preparing the radiation shielding composite material according to claim 1, comprising the following steps: The first polymer-based shielding layer is placed in the magnetron sputtering cavity for metal sputtering to obtain a metal coating. A second polymer-based shielding layer is coated onto the surface of the metal coating, and then hot-pressed to obtain a radiation shielding composite material. The specific methods for preparing the first polymer-based shielding layer and the second polymer-based shielding layer are as follows: The matrix resin, shielding powder, and dispersant are added to a twin-screw extruder and mixed and extruded at 100~120℃.

4. The preparation method according to claim 3, characterized in that, The gas pressure inside the magnetron sputtering cavity is 2~5×10⁻⁶. - 3 Pa, the metal sputtering time is 2~10h.

5. The preparation method according to claim 3, characterized in that, The hot pressing temperature is 50~150℃, the pressure is 0.2~0.5MPa, and the time is 5~10s.

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