JPH08122492A - Radiation shielding material and manufacture thereof - Google Patents

Abstract

PURPOSE: To provide a radiation shielding material which is hygienic, having high efficiency of radiation shielding, capable of being easily formed and processed at a low cost, easy to use and capable of being used at a movable part, and to provide a manufacturing method thereof. CONSTITUTION: A radiation shielding material is constituted of a compound of particles of a material having a high radiation absorptivity, a resin and a plasticizer that imparts plasticity to the resin, whereby the particles are enclosed with the resin having the plasticity, then the material has, as a whole, the plasticity. The radiation shielding material is manufactured such that the particles of the material having the high radiation absorptivity, resin, plasticizer and a solvent are mixed to make a slurry, it is formed in a prescribed shape and the solvent is removed by drying.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material intended for radiation shielding and a method for producing the same, and not only as a radiation therapy shielding material but also as a radiation shielding material for nuclear power and industrial / medical CT.
The present invention relates to a radiation shielding material used in the field of radiation shielding such as scanning.

[0002]

When using radiation in the medical field,
In radiation therapy and measurement, irradiate only the target area with the required amount of radiation, and do not irradiate the areas that do not need to be irradiated to prevent the destruction of normal cells and unnecessary exposure. is necessary. However, since it is difficult to irradiate only the part to be irradiated with radiation,
A shielding material for shielding radiation is used in areas other than the necessary parts.

Conventionally, lead or a lead alloy has been generally used as the radiation shielding material, and an acrylic plate or the like has been used in the case of relatively weak radiation. Further, a tungsten plate is used in part.

When lead or a lead alloy is used as the shielding material, a mold is prepared to have a predetermined shape, and the lead or the lead alloy is melted in the mold for casting, or a lead having a diameter of several mm is used. Alternatively, there is a method in which a lead alloy sphere is prepared, poured into a mold made in a predetermined shape and used. Furthermore, when an acrylic plate or the like is used as the shielding material, it is cut into a predetermined shape and used. When a tungsten plate is used as the shielding material, it is usually used by rolling and / or cutting it into a predetermined shape.

However, there are various problems in using the shielding material in the above method. First, when lead or a lead alloy is used as the shielding material, the cost is very high because of the melting of lead and the creation of a mold to obtain a predetermined shape. There was a problem of adverse effects on the human body. Further, even after the predetermined shape is obtained, there is a sanitary problem that the surface of the shielding material is corroded and the corrosive components are released during the handling.

Next, when an acrylic plate or the like is used as the shielding material, it is necessary to increase the thickness of the shielding material because its radiation shielding ability is low. For this reason, there is a problem that cutting is difficult, special equipment is required, and the cost becomes high.
Furthermore, when using a tungsten plate as the shielding material,
Since the material has a high specific gravity and is hard and brittle, it may be damaged due to its own weight or impact depending on its handling, and it may become unusable.In addition, it is very difficult to cut and process and it is expensive. It was

Finally, in all of the above-mentioned materials, when the shielding material such as a movable part is used in a stressed area,
Destruction due to stress or fatigue occurred, making it virtually impossible to use.

[0008]

As described above, lead or lead alloys, tungsten plates, acrylic plates, etc. have been used in the conventional radiation shielding materials, but these materials are used to obtain a predetermined shape. There are problems such as high cost of molding and processing, problems of hygiene, and unusability of movable parts. Further, when a tungsten plate is used, there is a problem that its handling is very difficult.

In view of such conventional circumstances, the present invention has a hygienic alternative to the above materials and has a high radiation shielding ability,
It is an object of the present invention to provide a radiation shielding material that can be molded and processed inexpensively and easily, is easy to handle, and can be used even in movable parts, and a manufacturing method thereof.

[0010]

In order to achieve the above object, the radiation shielding material provided by the present invention comprises a powder of a material having a high radiation absorptivity, a resin agent, and a plastic agent for imparting plasticity to the resin agent. It is characterized in that it is composed of a mixture with a plasticizer, the powder particles are surrounded by the resin agent having plasticity, and the entire material has plasticity.

The method for producing a radiation shielding material provided by the present invention is a powder of a material having a high radiation absorption rate, a resin agent, a plasticizer for imparting plasticity to the resin agent, and the resin agent and / or The method is characterized in that a solvent for dissolving the plasticizer is mixed and made into a slurry state, then shaped into a predetermined shape, and the solvent is dried and removed.

[0012]

In the radiation shielding material of the present invention, a material having a high radiation absorptivity is made into a powder, and the powder is mixed with a resin agent and a plasticizer for imparting plasticity to the resin agent. Since each particle is surrounded by the resin material having plasticity, the entire material has plasticity.

Therefore, the radiation shielding material of the present invention is easy to handle, is extremely easy to process, can significantly reduce the processing cost, and contains a material powder having a high radiation absorption rate in order to obtain a high radiation shielding ability. Even if the amount is increased to make the entire material have a high specific gravity, there is no damage due to its own weight or impact.

Further, since the material as a whole has plasticity, it can be used not only for shielding movable parts, which cannot be used with conventional materials, but also for shielding curved surfaces by using a sheet shape or the like. It is possible to easily adhere to each other by utilizing the plasticity.

Further, in this radiation shielding material, since the powder of the material having a high radiation absorption rate is surrounded by the resin agent, it is hygienic that the powder is detached during handling, and the powder material is corroded. The problem of does not occur either.

When tungsten, a tungsten compound, or a tungsten-based alloy is used as a material having a high radiation absorption rate, a high radiation shielding ability can be obtained, and in addition to the case where lead or a lead alloy is used, the environment In addition, it is possible to provide a hygienically safe product with almost no adverse effects on the human body.

A material having a high radiation absorption rate is used as a powder, and the content rate of this powder is preferably 90 to 99% by weight based on the whole. By setting the powder content to 90% by weight, it is possible to obtain a radiation shielding ability that is equal to or better than that of conventional radiation shielding materials made of lead or lead alloy, and 10 times that of conventional acrylic plates. This is because it is possible to obtain a degree of radiation shielding ability. On the other hand, if it exceeds 99% by weight, it becomes difficult for the powder particles to be surrounded by the resin agent,
The plasticity of the entire material cannot be maintained.

The particle size of the powder of a material having a high radiation absorption rate is preferably 50 μm or less. By having such a particle diameter, the powder particles are easily surrounded by the resin agent, the plasticity of the entire material is easily maintained, problems such as crack generation in handling are eliminated, and reliability is further improved. is there.

On the other hand, in the production of the radiation shielding material of the present invention, a powder of a material having a high radiation absorption rate, a resin agent, a plasticizer for imparting plasticity to the resin agent, and the resin agent and / or the plasticizer are used. This can be carried out by a method in which a solvent for dissolution is mixed, made into a slurry, then shaped into a predetermined shape, and the solvent is dried and removed.

This method has a simple process, and by selecting an appropriate resin agent, plasticizer, and solvent, the radiation shielding material can be produced at room temperature without the need for heating, etc. Therefore, the production cost can be reduced.

Further, in forming, since it is made into a slurry, it is possible to use casting or slip casting method when forming into a predetermined shape, and therefore, it is possible to form into any shape, and post-processing is reduced, The cost can be further reduced.

Further, in the case of lead, lead alloys, acrylic plates or tungsten plates which have been generally used in the past, it is not possible to use them repeatedly, or re-melting is required, but the cost is high. According to the method of the invention, by remixing the solvent or by partially removing the resin agent or the plasticizer component, it is possible to easily re-slurry, so that repeated molding is possible, and the raw material In addition, the remolding cost can be significantly reduced.

Furthermore, by using tungsten, a tungsten compound, or a tungsten-based alloy as a material having a high radiation absorption rate, it is difficult for decomposition or chemical reaction to occur in these powders in the manufacturing process, and repeated use is possible. Compared with the shielding material of lead or lead alloy,
There is an advantage that there is little deterioration of the working environment and adverse effects on the environment and the human body.

[0024]

Example: 95% by weight of W powder having an average particle diameter of 3 μm, 3% by weight of polyvinyl butyral as a resin agent, and 2% by weight of di-n-butyl phthalate as a plasticizer were weighed, and based on the total weight thereof. 30 wt% trichlorethylene was added as a solvent and mixed for 1 hour. The obtained slurry is 0.3 mm thick by slip casting method.
After being formed into a sheet shape, the solvent was dried at room temperature to obtain a molded body.

Observation of the obtained molded body revealed that each particle of the W powder was surrounded by the resin agent, and the entire material had plasticity. The density of this molded body was 10 g / cm ³ , and the radiation shielding ability was almost the same as that of a lead plate having the same thickness.

Further, in this molded product, desorption of W powder particles was not observed in handling. Further, when an attempt was made to cut this molded body, it was found that it could be easily cut with ordinary scissors, a cutter knife, etc., and could be processed extremely easily and inexpensively.

Next, when this molded body was cut into a length of 100 mm and a width of 50 mm and naturally dropped from a height of 2 m onto an iron plate having a thickness of 5 cm, no cracks or damages occurred. When the same drop test was performed on the W plate having the same size, breakage was recognized.

Further, the molded body having the same shape and the lead alloy are
When the lead alloy was kept for 100 hours in an environment of a temperature of 60 ° C. and a humidity of 90%, corrosion was observed in the lead alloy, but no corrosion was observed in the molded body.

The slurry obtained by mixing in the same mixing ratio as described above is poured into a mold having a length of 100 mm, a width of 50 mm and a thickness of 5 mm, dried at room temperature in the same manner as described above, and taken out from the mold. It has been found that the characteristics and physical properties of the body are the same as those of the molded body obtained by the slip casting method, and this molded body can be easily molded into a required shape.

In addition, these molded bodies are added with a total weight of 3
When 0% by weight of trichloroethylene was added and mixed for 1 hour, it became slurry again and it was found that repeated molding could be easily performed.

As a material having a high radiation absorptivity, it is possible to use Mo or a compound or alloy thereof in addition to W, and the types and mixing ratios of the resin agent, plasticizer and solvent are W and the like. Can be appropriately selected depending on the type of powder, the required radiation shielding ability, the required plasticity, and the like. It is also possible to add a dispersant or the like at the time of mixing for the purpose of improving the dispersibility of the powder.

[0032]

EFFECTS OF THE INVENTION According to the present invention, it is hygienic, has a high radiation shielding ability, can be manufactured at low cost, is cheap and simple to mold and process, is easy to handle, and can be mounted on a movable part. It is possible to provide a radiation shielding material that can also be used. Further, this radiation shielding material can be easily formed into a required shape, and can be repeatedly molded and used.

Claims (8)

[Claims] 1. A mixture of powder of a material having a high radiation absorption rate, a resin agent and a plasticizer for imparting plasticity to the resin agent, wherein the powder particles are surrounded by the resin agent having plasticity. The radiation shielding material is characterized in that the entire material has plasticity. 2. The radiation shielding material according to claim 1, wherein the material having a high radiation absorption rate is any one of tungsten, a tungsten compound, and a tungsten-based alloy. 3. The powder of a material having a high radiation absorption rate is 90-
99% by weight is contained, The radiation shielding material of Claim 1 or 2 characterized by the above-mentioned. 4. The radiation shielding material according to claim 1, wherein the powder of the material having a high radiation absorption rate has a particle size of 50 μm or less. 5. A slurry prepared by mixing powder of a material having a high radiation absorption rate, a resin agent, a plasticizer for imparting plasticity to the resin agent, and a solvent for dissolving the resin agent and / or the plasticizer. A method for producing a radiation shielding material, which comprises shaping the material into a predetermined shape, and then drying and removing the solvent. 6. The method for producing a radiation shield according to claim 5, wherein the material having a high radiation absorption rate is any one of tungsten, a tungsten compound, and a tungsten-based alloy. 7. The method for producing a radiation shielding material according to claim 5, wherein the powder of the material having a high radiation absorption rate is 90 to 99% by weight of the whole. 8. The powder particle size of a material having a high radiation absorption rate is set to 5
The method for producing the radiation shielding material according to any one of claims 5 to 7, wherein the radiation shielding material has a thickness of 0 µm or less.