KR102186031B1 - Composition for shielding radiation and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a composition for shielding radiation and a manufacturing method thereof. The composition for shielding radiation is made of a polymer resin composed of bismuth (Bi) powder and at least one of polypropylene (PP) or polylactic acid (PLA). According to the present invention, the composition for shielding radiation does not generate cracks even during long-term high-temperature treatment, and has excellent shielding effect against radiation.

Description

Composition for shielding radiation and manufacturing method thereof TECHNICAL FIELD

The present invention relates to a composition for radiation shielding and a method for manufacturing the same, and more particularly, to a composition for radiation shielding having excellent radiation shielding effect and a method of manufacturing the same, without causing cracks even during long-term high-temperature treatment.

Radiation is harmful to the human body enough to cause physical damage that can tear body cells, and it is a deadly energy flow that can accumulate in the body the more it is hit, and thus deform or destroy the cells of the body. High-dose radiation is also a big problem, but it focuses on shielding low-dose radiation that affects our daily environment. Although the distinction between low and high doses is not clear, there is a content that 100 mSv is currently a provisional reference point in terms of no clear evidence on whether risk factors such as cancer occur when exposed to radiation doses of less than 100 mSv.

Radiation shielding materials are mostly made of existing lead (Pb) materials, and lead is increasingly regulated as an environmentally hazardous material. Lead is a heavy metal material and is a dangerous substance that can cause lead poisoning by generating lead gas during processing. However, bismuth is a chemical element with less harmful properties than lead, and it can be expected to prevent exposure to organs in the human body by shielding low-dose radiation. Bismuth (Bi) has an atomic number of 83, an atomic weight of 208.980, a melting point of 271.3 ℃, a density of 9.747 g/cm3 at room temperature, and a bismuth compound that does not contain lead is a metal component mainly used in cosmetics and medical treatment. to be. It has excellent physical flexibility and can be processed into various shapes. In addition, it is recently evaluated as a lead substitute material that is harmful to the human body, and has attracted attention as a radiation shielding material due to its excellent shielding rate.

However, in order to use only such bismuth metal as shielding, the cost is high to manufacture and process in various forms, and it is difficult to develop a complex shape into a metal and a thin material.

On the other hand, plastic materials are easy to process in the form of a thin film and are easy to thermally decompose, mold, and mix with thermoplastic resins. In addition, thermoplastic resins melt when heated, but return to their original state when cooled, so they can be easily recycled. Nevertheless, waste plastics used in construction or agricultural sites are facing various environmental problems, and when treated as air pollution, they generate pollutants such as nitrogen oxides, dioxins, and heavy metals when incinerated, and methane gas when landfilled. In terms of water quality, environmental regulations are required as BOD, COD, and other heavy metals are generated during wastewater reclamation.

Therefore, if plastic with excellent processability and metal with excellent radiation shielding effect are made into a composite and used as a shielding material for body organs, it can be economically advantageous as well as solve environmental pollution. In particular, shielding functional plastics and aggregated shielding blends Materials such as daily life, construction sites, the Ministry of Defense, and agriculture are expected to have a lot of demand throughout the industry by expanding the fields, and waste plastics will be used to recycle resources and lead eco-friendly businesses.

1. Patent Registration No. 10-1591965 (Lead-free multi-layered composite radiation shielding material containing low melting point bismuth-tin alloy and manufacturing method thereof) 2. Patent Registration No. 10-1949541 (Energy Shielding Plastic Film)

The present invention is to solve the above problems, and the existing product is a product made by dispersing bismuth in a urethane or rubber material, but the object of the present invention is to cause cracks even during long-term high-temperature treatment through a specific plastic material using bismuth powder. It is an object of the present invention to provide a radiation shielding composition and a method for manufacturing the same, which has excellent shielding effect against radiation without doing so.

The radiation shielding composition of the present invention for achieving the above object is characterized in that it is made of a polymer resin made of at least one of bismuth (Bi) powder and polypropylene (PP) or polylactic acid (PLA).

Another method of manufacturing a radiation shielding composition according to the present invention is a first step of preparing a bismuth (Bi) powder, a first step of preparing a polymer resin by melting at least one of polypropylene (PP) or polylactic acid (PLA). It characterized by including a second step and a third step of preparing a radiation shielding composition by mixing bismuth (Bi) powder and the polymer resin.

The technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems that are not mentioned can be clearly understood by those of ordinary skill in the technical field to which the present invention belongs from the following description. There will be.

According to the present invention, there is provided a radiation shielding composition and a method of manufacturing the same, which does not generate cracks even during long-term high-temperature treatment, and has excellent shielding effect against radiation.

1 is a view showing a distribution diagram to confirm the mixing degree of bismuth-mixed plastic polymers.
2 is a diagram showing samples applied for a radiation shielding performance test.
3 is a view showing a comparison of the radiation shielding effect between a bismuth mixed polymer versus an unmixed polymer.
4 is a view showing a comparison of the shielding rate with other companies compared to the bismuth mixed polymer.

Hereinafter, the present invention will be described in detail, and detailed descriptions of known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

The radiation shielding composition of the present invention is composed of a polymer resin composed of bismuth (Bi) powder and any one or more of polypropylene (PP) or polylactic acid (PLA), and is excellent against radiation without cracking even during long-term high-temperature treatment. It is characterized by showing a shielding effect.

Hereinafter, a detailed look at the manufacturing process of the radiation shielding composition of the present invention is as follows.

(Process of manufacturing radiation shielding film composition)

1. Step 1: Preparation of bismuth powder

Bismuth is an element belonging to the nitrogen group element of Group 15 of the periodic table with an element symbol Bi, atomic weight of 208.9804, melting point of 271.44 ℃, and specific gravity of 9.80 (20 ℃). It is calculated as ore and is a metallic substance used for pigments and cosmetics. Among the metals, materials with shielding effects include lead (Pb), barium sulfate (BaSO ₄ ), tungsten (W), and bismuth (Bi).

Lead is a heavy metal substance that can cause lead poisoning by generating lead gas during processing. It is very harmful to the human body, and its use is regulated. Symptoms of lead poisoning include speech disorder, headache, abdominal pain, anemia, and motor paralysis. In the case of tungsten, it is difficult to apply due to its low dispersing power and high specific gravity when producing a product, and it is difficult to apply due to its high unit cost, whereas the bismuth has excellent dose reduction effect, excellent workability, and physical flexibility. It has been reported as a material that can be expected to have a shielding effect against unnecessary radiation exposure to deep and lesion-free organs in patients during general X-ray and CT examinations.

Accordingly, the newly developed bismuth, which has the same shielding effect as lead, and which can be lightened, was applied as a lead substitute. As a result of examining the usefulness in actual clinical application, it was shown in Table 1 below.

The test conditions were conducted by applying the KS standard to 100 kVp and 5 mAs. As a result of the test, the weight of the BF (Film type) sample and BF2 (the film type of adhesive material for high frequency heating purposes) among the bismuth-based samples It was evaluated as the lightest and the shielding rate was also excellent, and it was noted that the application of BF and BF2 was more useful when considering both the reduction of external exposure and weight reduction in clinical application.

Bismuth shielding rate test result
Layer/Absorption Dose(μGy)/Shielding rate(%) Bismuth
Base B2 BF BF2 1 page 746.90 59 1 page 153.94 92 1 page 123.84 93 Chapter 2 484.94 73 Chapter 2 128.10 93 Chapter 2 100.22 94 Chapter 3 337.52 82 Chapter 3 113.20 94 Chapter 3 74.97 96 Chapter 4 267.84 85 Chapter 4 102.70 94 Chapter 4 61.80 97 Chapter 5 210.56 89 Chapter 5 89.40 95 Chapter 6 171.94 91 Chapter 6 69.90 96 Chapter 7 143.98 92 Chapter 7 66.20 96 Chapter 8 119.84 93 Chapter 8 84.04 97 Chapter 9 97.87 95 Chapter 10 82.92 95 Chapter 11 64.89 96 Chapter 12 55.33 97

In other words, the bismuth is a material that is lighter than lead, tungsten, barium sulfate, etc., has excellent biocompatibility, and can be effectively used even in low-dose radiation, and may be provided as a powder having a particle size of 3 to 5 μm.

In addition, as the type of bismuth, any one or more of bismuth oxide (Bi ₂ O ₃ ), sodium bismuth (BiNaO ₃ ), and bismuth nitrate (BiN ₃ O ₉ ) can be selected and used, and more preferably bismuth oxide As an example, it is best to apply bismuth oxide (Assay 99.9%) of Duksan Chemical Co., Ltd. as follows.

2. Second process: manufacturing waste plastic polymer resin

In this process, a polymer resin is manufactured by melting any one or more of polypropylene (PP) or polylactic acid (PLA), which has the highest shielding performance while having no cracking and suitable hardness among various waste plastics.

In other words, crystalline materials are mainly used for plastic resins that combine conventional metals and plastics. Among them, polyester (PBT), nylon (Nylon, PA), and polyphenylene sulfide (PS) are the most used. There are conventional methods of using heavy metals as lightweight materials or mixing polymers with high flexibility. Bismuth also has a problem because it is not easy to process into various shapes and thin materials only by its metallic properties, and the cost of bismuth powder itself is high, so it takes a lot of cost to process it alone.

On the other hand, plastic polymers are easy to process into a thin film form, are inexpensive, are very soft, and have good deformability, so they can be easily transformed into complex shapes.

Accordingly, in the present invention, in order to prepare a material that complements the advantages and disadvantages of the metal component and the polymer component by mixing these two properties, in this step, the plastic is melted to produce a polymer resin.

At this time, any one or more of polypropylene (PP) or polylactic acid (PLA) is used as the type of plastic applied.

In other words, polypropylene (PP) or polylactic acid (PLA) has a certain strength without cracking through the curing process after melting and at the same time has a higher shielding ability than other plastic polymer resins. It is very suitable to achieve the effect.

Such polypropylene (PP) or polylactic acid (PLA) is in a hard form, and when simply mixed with the bismuth powder, it is difficult to exhibit an increased shielding effect.

Thus, the polypropylene (PP) or polylactic acid (PLA) is prepared in the form of pellets, and then melted at 160 to 170°C to prepare a polymer resin.

3. Third process: Preparation of radiation shielding composition

In this process, the bismuth (Bi) powder and the polymer resin are mixed to prepare a radiation shielding composition.

To explain, the inventors of the present invention confirmed the bonding property of the polymer property by combining the bismuth (Bi) powder, which is a metallic property, and PE, PP, PET, and PLA, which are mixed polymers, as described in the following experimental examples, and the mixed polymer sample The radiation shielding values for the polymer samples not mixed with and were also measured.

As a result, it was confirmed that the polymer mixed with all of PE, PP, PET, and PLA had poor bonding properties, and a sample sample was prepared in which each bismuth powder was mixed. In other words, bismuth powder was applied to the existing plastic polymer by testing the radiation shielding rate for each polymer by applying a bismuth-free polymer and a bismuth-mixed polymer sample to the size of 50 mm × 50 mm × 25 mm. It was confirmed that a higher shielding effect appeared when the sample was measured by adding. The shape, shape, and size of samples were checked according to PE, PP, PET, and PLA mixed with bismuth powder with shielding effect, and the shielding effectiveness of each sample was confirmed in the order of PP> PET> PLA> PE, but PET cracks. The result was that PE had a relatively low shielding rate. Compared to the bismuth-free polymer, the shielding efficiency of the bismuth mixed polymer sample was about 2.3 times for 60 kVp, 2.4 times for 80 kVp, and 2.5 times for 100 kVp. The higher the tube voltage value, the better the shielding effect is. Confirmed the content.

As a result of conducting an experiment based on 0.25 mmpb based on the Ministry of Food and Drug Safety, the average shielding rate was measured on a 60 kVp standard for a sample mixed with polymer and bismuth. A shielding rate of 87.92% was shown, and the shielding effect was predicted to be more effective as the thickness of the sample was increased. As a result, it was confirmed that even a small amount of bismuth mixture is effective in low-dose shielding for construction materials.

Accordingly, in the present invention, a composition for radiation shielding is prepared by mixing the bismuth (Bi) powder and the polymer resin having the most excellent shielding effect, and more preferably, the bismuth (Bi) powder and the polymer resin are 1:6~ It is characterized in that it has the best shielding effect by mixing in a weight ratio of 8, which is uneconomical because the content of bismuth is relatively high when the content of the polymer resin is less than 6 weight ratio. This is because the content of bismuth is relatively small, which slightly degrades the desired shielding effect. This mixing ratio can be changed according to the manufacturing method.

The radiation shielding composition prepared in this way may be prepared in the form of a sheet or using the mixed radiation shielding composition for a building aggregate. Specifically, the radiation shielding composition may be manufactured in a sheet form through extrusion molding, calendering, mold molding, etc., in which case, the sheet may be manufactured as a sheet having a thickness (t) of 0.1mm to 10mm.

Hereinafter, the present invention will be described in more detail with reference to experimental examples, but these experimental examples are for illustrative purposes only and are not intended to limit the protection scope of the present invention.

<Experimental Example 1> Experiment to derive materials usable as a radiation shielding film

After processing the waste plastic materials PE, PP, PET, PLA into aggregate form, each of them is treated with bismuth powder of 3 to 5 μm, and the irradiation conditions are controlled by tube current of 20 mA under the conditions of tube voltages of 60 kVp, 80 kVp, and 100 kVp. It was run for 0.25 Sec in mAs. The experiment was conducted by measuring the radiation shielding level of the waste plastic sample mixed with bismuth and the waste plastic sample not mixed. Bismuth is a metallic substance and has a heavy nature, so it is difficult to mix it physically with waste plastics, and its surface characteristics are also completely different, so bismuth powder is mixed on the surface of waste plastics by controlling the amount of bismuth powder in each waste plastic sample PE, PP, PET, PLA The experiment was conducted in a way of treating.

Specifically, it is as follows.

① Test piece production

Changes were observed after melting the bismuth powder melting point of 271 °C and the melting point of waste plastics of 170 °C. Bismuth and waste plastic tissues were subjected to thermal changes, and the amount and size of waste plastics were adjusted to perform the experiment. Changes were also observed when the two products were mixed and melted. In the case of bismuth powder, bismuth oxide of Duksan Chemical Co., Ltd. was used. In the case of PE, PP, PET raw materials, it was supplied from Ace Polymer, and in the case of PLA raw materials, it was supplied from Dowon Biotech.

The experiment was conducted in consideration of the melting points of PE (Polyethylene), PP (Polypropylene), PET (Polyethylene terephthalate), PLA (Poly lactic acid), and bismuth, and the numerical values for the shielding effect that appeared when the material was melted were measured. .

It was confirmed that the shielding effect was maintained even when the two materials were mixed, and the experiment was conducted in consideration of environmental aspects. PE, PP pelletized in bismuth powder with an average particle size of 3 to 5 μm and a purity of 99% of bismuth powder. PET and PLA raw materials were mixed.

② Preparation of mixed sample of bismuth and waste plastic

The amounts of plastic materials PE, PP, PET, PLA and bismuth powder were classified and designated as samples. The test sample of the plastic film was carried out in a format in which a sample of PET + Bi was mixed with PE and PP. The main raw material was designated as bismuth oxide powder, and the amount of each mixed powder was 30 g to prepare a mixed sample. The final mixed plastic film and bismuth powder were subjected to a mixing experiment using heat treatment. The shielding rate when mixed with plastic film materials according to the size and amount of the bismuth powder was measured. Experimental temperature was conducted at 165.5℃.

First, 200 g of pelletized PET and 30 g of bismuth oxide powder were heated at a constant temperature to conduct the experiment. For mixing of the two properties, 200 g of PET was first melted, and then bismuth powder was added and mixed. It was confirmed that the existing color of the existing bismuth powder was pale yellow. When only the existing PET was melted, it had a colorless light, and when the bismuth powder was mixed and melted, it was confirmed that the color changed to dark. When the two materials were mixed and solidified, it became a material with very hard properties, and it was observed that cracks occurred after a certain period of time.

Then, 200 g of pelletized PLA and 30 g of bismuth oxide powder were heated at a constant temperature to conduct the experiment. For mixing of the two properties, 200 g of PLA was first melted and then bismuth powder was added and mixed. It was confirmed that the existing color of the existing bismuth powder was pale yellow, and when only the existing PLA was melted, it had a light green light, and when the bismuth powder was mixed and melted, it turned dark green. When the two materials were mixed and solidified, it was observed that the material was very hard and did not crack.

③ Preparation of bismuth mixed sample with waste plastic material construction aggregate

Based on the contents of the measured sample, bismuth powder was mixed with the waste plastic construction aggregate. After the first processing, the amount and density of the bismuth powder and the waste plastic were measured to confirm the contents of the surface powder. Thus, the secondary processing was performed and the powdered powder adhered to the surface was mixed and treated to prepare a mixed sample of plastic and bismuth powder (Table 2).

Bismuth content compared to waste plastic PE (200g) + Mixing Agent (PET 200g + Bi 30g)
PP(200g) + Mixture (PET 200g+Bi 30g) PE (200g) + Aggregate (30g) + Mixture (PET 200g + Bi 30g)
PP (200g) + Aggregate (30g) + Mixture (PET 200g + Bi 30g) PLA(200g) + Blending agent (PET 200g+Bi 30g)

The performance measurement was performed by dividing the mixed polymer PE, PP, PET, PLA 200 g and bismuth content by 30 g ratio.

First, for the experiment, an experiment was conducted with a pelletized polymer. When each of the waste plastics was individually melted, it was confirmed that it turned into a liquid state and then solidified. Polymers of PE, PP, and PET were mixed and melted, but the melting point was different so that they were not mixed and were aggregated and not mixed. Accordingly, it was confirmed that a separate mixing machine was required for mixing the polymer.

In other words, in the case of PE, it was confirmed that it gradually became liquid when it reached about 140°C. PP started to melt slowly when heated to about 160°C, and PET started to melt when heated to about 260°C. As a result of checking the melting point, it was confirmed that the melting point was the lowest in the order of PE, followed by PP and PET. Thus, PE, PP, and PET were individually melted to confirm the following sample samples. First, PE was melted and PET + Bi was mixed to prepare a sample. In this way, PP was melted and PET + Bi was mixed to prepare a second sample. The PET+Bi mixture was mixed with the polymer sample twice. I did.

It was judged that the PET + Bi mixture was not suitable as a mixture due to the problem of cracking after curing. For this, 200 g of each polymer was mixed with 30 g of Bi to prepare a mixture. When PET is melted, it is easy to liquefy, but when it is solidified, cracking and cracking were observed, and the strength was confirmed to be low. When PE is melted, it is difficult to liquefy and has a sticky property. When it is solidified, cracks do not occur, and the strength is confirmed at an average level.

The strength of PP when melted is between 1 and 7 and was confirmed as an average level among polymers. When PLA is melted, it is difficult to liquefy and has a strong adhesive property. When it is solidified, it does not crack and has high strength.

As a result of testing with the prepared blending agents PLA + Bi, PP + Bi, and PE + Bi, it was confirmed that PE + Bi, PP + Bi, and PLA + Bi were the optimal blending agents with hard strength without cracking. Another reason is that it has higher strength than other comparative polymer samples, and the deformation temperature also shows PET 260℃, PP 160℃, PE 130℃, PLA 170℃. It was confirmed that PP + Bi or PLA + Bi material is suitable as a material showing the efficient melting property.

<Experimental Example 2> Confirmation of the shape of the Bi-plastic composite

As shown in FIG. 1, the shape of the surface composite measured by SEM (Scaning Electron Microscope) of the mixed polymer shows that the mixing was well performed. When checking the red square within the section of size 500 µm × 500 µm, the distribution of the number of bismuth powder particles was confirmed in the data expanded by 500 times, and the distribution of the number of bismuth powder particles was confirmed. It was confirmed that the bismuth powder was evenly mixed with a distribution of ~ 15, and the mixing degree of the bismuth powder with the polymer was confirmed in the order of PLA> PP> PE> PET as a result of the study.

<Experimental Example 3> Validation of the efficacy of the radiation shielding film

The waste plastic aggregate samples were mixed with bismuth powder to conduct the experiment.

As an experiment type, X-ray shielding rate measurement (using an X-ray equipment), and measurement of the size and thickness of a sample (using a surface thickness measuring device) were performed, and microparticles were observed.

Shielding performance test conditions are shown in Table 3 below.

Shielding rate test inspection 1. Sample size and number 8 ea(50×50×25mm) 2. Shielding performance division 60kVp 80kVp 100kVp Reference dose (uR) Reduced dose (uR) Shielding rate (%)

In this shielding performance experiment, the samples were compared with polymers not containing bismuth and polymers containing bismuth, respectively, and 11 samples of Table 4 and FIG. 2 were used.

sample No. Remark PP polymer 1-1 Without bismuth PP + Bi 1-2 Bismuth coating PLA polymer 2-1 Without bismuth PLA + Bi 2-2 Bismuth coating PE polymer 3-1 Without bismuth PE + Bi 3-2 Bismuth coating PET polymer 4-1 Without bismuth PET + Bi 4-2 Bismuth coating PET + Bi 5-1 Bismuth mixed polymer PE + Bi 6-1 Bismuth mixed polymer PLA + Bi 7-1 Bismuth mixed polymer PP + Bi 8-1 Bismuth mixed polymer

The following experiments were conducted under the conditions of a tube voltage of 60 kVp / 80 kVp / 100 kVp, a tube current of 200 mA, and a time of 0.25 sec and 50 mAs, with the same radiation values for the sample sample without polymer and bismuth and the sample including polymer and bismuth. And measured. At this time, the applied shielding rate formula is as follows.

* Shielding rate formula: ((NON dose average value-dose average value after passing the sample)/NON dose average value) × 100

As a result, it was shown in Tables 5,6,7,8 below.

Tube voltage
kVp sample Baseline dose
mGy Reduced dose
(No polymer)
mGy
% Reduced dose
(Coating polymer)
mGy
% One 2 One 2 60
kV PP 4,462 2,640 2,642 40.81 364 364 91.84 Avr 2,641 Avr 364 PLA 2,742 2,747 38.48 538 539 87.92 Avr 2,745 Avr 539 PE 3,020 3,020 32.31 671 671 84.96 Avr 3,020 Avr 671 PET 2,736 2,739 38.63 418 418 90.63 Avr 2,738 Avr 418

Tube voltage
kVp sample Baseline dose
mGy Reduced dose
(No polymer)
mGy
% Reduced dose
(Coating polymer)
mGy
% One 2 One 2 80
kV PP 7,007 4,490 4,492 35.90 912 912 86.98 Avr 4,491 Avr 912 PLA 4,590 4,588 35.50 1,207 1,207 82.77 Avr 4,589 Avr 1,207 PE 4,944 4,951 29.38 1,446 1,447 73.34 Avr 4,948 Avr 1,447 PET 4,590 4,592 34.47 998 998 85.75 Avr 4,591 Avr 998

Tube voltage
kVp sample Baseline dose
mGy Reduced dose
(No polymer)
mGy
% Reduced dose
(Coating polymer)
mGy
% One 2 One 2 100
kV PP 9,675 6,544 6,544 31.32 1,720 1,719 82.22 Avr 6,544 Avr 1,720 PLA 6,602 6,607 31.73 2,115 2,116 78.12 Avr 6,605 Avr 2,116 PE 7,015 7,017 27.83 2,483 2,485 74.32 Avr 7,016 Avr 2,484 PET 6,621 6,622 31.55 1,822 1,824 81.15 Avr 6,622 Avr 1,823

Tube voltage
kVp sample Baseline dose
mGy Reduced dose
(Mixed polymer)
mGy % One 60kV 5 4,462 289 93.48 6 728 83.68 7 55 98.76 8 118 97.35 80kV 5 7,007 817 88.34 6 1,608 77.05 7 266 96.20 8 312 95.54 100kV 5 9,675 1,639 83.05 6 2,813 70.90 7 683 92.94 8 812 91.60

As shown in Tables 5, 6, 7, and 8, it was confirmed that the shielding rate decreased as the tube voltage increased, and when the experiment was conducted with a value of 60 kVp, the shielding rate was measured as the highest.

It was detected that the shielding ability was different depending on the material of the plastic sample, but it was confirmed that the shielding efficiency was different about 1 to 3% of each sample. The shielding efficacy of each sample was found to be higher in the polymer containing bismuth than the non-polymer, and among the polymers containing bismuth, PP+Bi> PET+Bi> PLA+Bi> PE+Bi were found in order. In particular, it was confirmed that the shielding effect was more excellent in the mixed polymer than the coating.

<Experimental Example 3> Comparison of shielding performance of samples with 0.25 mmpb of lead equivalent based on the Ministry of Food and Drug Safety

Using a polymer sample having a size of 50 mm × 50 mm × 25 mm (width × length × height), the radiation shielding rate was examined and the average value was calculated.

The size and thickness of the sample was measured using Crownman's Electronic Digital Calipers, and numerical measurements of 0 ~ 150 mm thickness are possible.

The specifications of the bismuth polymer are shown in Table 9 below.

Thickness(T/mm) Polymer sample without Bi Bi mixed polymer sample PP 17.20 7.80 PLA 17.20 7.80 PE 17.20 7.80 PET 17.20 7.80

The radiation shielding rate test results were shown in Tables 10 and 11 and FIG. 3 below.

Classification 60 kVp 80 kVp 100 kVp PP 40.81 35.90 31.32 PLA 38.48 35.50 31.73 PE 32.31 29.38 27.83 PET 38.63 34.47 31.55 Shielding rate (%) 37.55% 33.81% 30.60%

Classification 60 kVp 80 kVp 100 kVp PP 91.84 86.98 82.22 PLA 87.92 82.77 78.12 PE 84.96 73.34 74.32 PET 90.63 85.75 81.15 Shielding rate (%) 88.84% 82.21% 78.96%

As a result of conducting an experiment based on the 0.25 mmpb standard based on the Ministry of Food and Drug Safety, the average shielding rate was measured on a 60 kVp standard for a sample mixed with polymer and bismuth. Showed. Compared to the bismuth-free polymer, the shielding efficiency of the bismuth mixed polymer sample was about 2.3 times for 60 kVp, 2.4 times for 80 kVp, and 2.5 times for 100 kVp. The higher the tube voltage value, the better the shielding effect. I confirmed the contents.

In addition, by comparing the contents of the radiation shielding performance test of other companies that produce the radiation shielding sheet <Inspection Agency: Radiation Safety Inspector affiliated with Korea Medical Equipment Inspection Institute> As a result of comparing the rates, it was shown in Table 12 and FIG. 4H.

* Other company's shielding sheet samples: Urethane resin solvent (Solvent), bismuth (Bi), thickness: 7.50mm (1.50mm × 5 layers)

kVp thickness 60 kVp 80 kVp 100 kVp Third party shielding sheet 7.50mm 96.21% 90.05% 83.10% Bismuth blend
PP polymer 7.80mm 91.84% 86.98% 82.22% Bismuth blend
PLA polymer 7.80mm 87.92% 82.77% 78.12%

As shown in Table 12, it was confirmed that there was no significant difference in the shielding rate when comparing the shielding rates for the bismuth mixed polymer tested with the data of the Ministry of Food and Drug Safety certification standards.

As described above, it was found that the present invention can provide a radiation shielding composition having an excellent shielding effect against radiation without generating cracks even during long-term high-temperature treatment.

The present invention has been looked at around preferred experimental examples, and those of ordinary skill in the art to which the present invention pertains can implement experimental examples of different types from the detailed description of the present invention within the essential technical scope of the present invention. I will be able to. Here, the essential technical scope of the present invention is shown in the claims, and all differences within the scope equivalent thereto should be construed as being included in the present invention.

Claims (3)

delete A first step of preparing bismuth (Bi) powder having a particle size of 3 to 5 μm;
A second process of preparing a polymer resin by manufacturing at least one of polypropylene (PP) or polylactic acid (PLA) in a pellet form, and then melting it at 160 to 170°C, and
Including; bismuth (Bi) powder and a third step of mixing the polymer resin in a weight ratio of 1: 6 to 8 to prepare a radiation shielding composition;
Method for producing a radiation shielding composition.
Produced by the manufacturing method of claim 2,
Composition for shielding radiation.

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