JP2016035397A - Radiation shield resin composition, radiation shield resin material, and radiation shield resin molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation shield resin composition which allows molding of a panel, block or sheet having an excellent radiation shielding property and which is excellent in workability at room temperature so that the inner surface of a container is coated with the composition to make a radioactive waste container.SOLUTION: Provided is a radiation shield resin composition 20 which includes, in a resin obtained by mixing an epoxy resin 1 with a hardening agent 2, as a radiation shielding substance, tungsten powders 3a and 3b having a particle size in the range of at least 1.5 to 16 μm, desirably 4 to 8 μm in an amount in the range in which the fluidity of the mixture is not lost at room temperature, and blended so that the specific gravity is 4 g/cmor higher. The tungsten powders 3a and 3b are preferably blended in forms of a fine grain having a particle size in the range of 4 to 8 μm and a coarse grain having a particle size in the range of 10 to 40 μm, and the blend ratio by weight thereof is desirably 3:1. In addition, when a silane coupling agent, an alkanolamine, an antifoamer, and a flexibility imparting agent are used in combination, the radiation shielding property, fluidity and physical properties become further desirable.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a radiation shielding resin composition, a radiation shielding resin material, and a radiation shielding resin molding, and more specifically, has excellent gamma (γ) ray shielding properties and has a workability at room temperature. Good radiation shielding resin composition, two-component radiation shielding resin material used for obtaining this radiation shielding resin composition, and radiation shielding resin molded using this radiation shielding resin composition It relates to a molded product.

  The Great East Japan Earthquake that occurred in March 2011 and the accompanying tsunami caused TEPCO's Fukushima Daiichi Nuclear Power Station to lose all its power source, resulting in a mass release accident of radioactive waste. Since then, we have been studying accident handling work in areas with high radiation doses (mainly gamma rays) centered on nuclear buildings and turbine buildings, but the radiation dose is extremely high, along with measures to prevent exposure to workers. Safe disposal of radioactive waste is essential.

In addition, the handling of radioactive waste in Japan is stipulated in the Nuclear Power Basic Law. For example, the low-level radioactive waste generated by the operation and dismantling of nuclear power plants and nuclear fuel processing plants and the above accident handling work is not It is said that it will be disposed of according to the radioactivity level.
Specifically, among low-level radioactive waste, those with relatively low radioactivity concentration are stored in a radioactive waste container such as a drum can, and a concrete pit (concrete) provided several meters (m) underground. The “shallow underground pit disposal” buried in the enclosure or the “shallow underground trench disposal” buried in the trench of the moat. On the other hand, among the low-level radioactive waste, those having a relatively high radioactivity level such as in-furnace structures (control rods) are said to be subjected to “marginal disposal”, for example, buried in the ground of about 50 to 100 m. (However, at present, of the low-level radioactive waste, those with relatively high levels of radioactivity are stored in nuclear power plants).

  Here, radiation, particularly γ-rays, which are considered difficult to shield compared to other radiations such as alpha (α) rays and beta (β) rays, will be described. Γ-rays are electromagnetic waves having a wavelength shorter than about 10 pm. Yes, the wavelength region partially overlaps the X (X) ray. In detail, the one that originates from the transition of the energy level in the nucleus is called γ-ray, and the one that originates from the transition of orbital electrons is called the X-ray. This γ-ray has a high transmission capability but a relatively weak ionization effect compared to α-rays and β-rays that are particle beams. However, this ionization action damages DNA, and gamma rays are considered to have a carcinogenic action. Moreover, since γ rays have a long range and no electric charge, they cannot be changed in direction using electromagnetic force, and are difficult to protect compared to other radiation.

Such γ-ray shielding is generally performed by a shielding material using a material having a large specific gravity, such as metallic lead, iron, or concrete. That is, since it is known that the gamma ray shielding ability is mainly determined by the density of the shielding material, a shielding material filled with a substance having a high specific gravity at a high concentration is used. For example, metallic lead has a specific gravity of 11.3 g / cm ³ and can attenuate the transmission amount of γ rays to 1/100 (1/100 valence layer) or less with a thickness of 10 cm.

  However, since metallic lead is toxic and accumulative, there is a problem in long-term use in the natural environment. That is, when molding a shielding material with metallic lead, it is necessary to heat and melt the lead itself before pouring it into the mold, but a toxic gas is generated during molding (350 ° C. or higher). Therefore, metallic lead is difficult to handle and requires advanced environmental management such as prevention of inhalation into the human body and regular health management of workers.

  Iron also has a relatively large specific gravity, but requires a very high molding temperature and has a problem of rust generation in coastal areas. Therefore, the application location is limited, for example, it is necessary to periodically paint to prevent rust according to the environment.

  In addition, concrete that has fluidity at room temperature and can be solidified at room temperature is also widely used as a γ-ray shielding material, but concrete has a long molding time and cracks due to aging. Sometimes. Therefore, regular maintenance is required, and the application location is limited for use as a stable γ-ray shielding material.

  Therefore, as a γ-ray shielding material used for the purpose of preventing human exposure in general environments including outdoors, it replaces harmful metallic lead and has excellent γ-ray shielding closer to the shielding ability of lead. What has the property is desired.

Then, the radiation shielding material using the resin composition which combined the thermosetting resin and high-density inorganic substances, such as lead monoxide and tungsten with comparatively low toxicity, is proposed (for example, refer patent document 1). .
This radiation shielding material has a specific gravity of slightly over 3 g / cm ³ , has good gamma ray shielding properties, and is better than general plastics and rubbers when an epoxy resin is used as a thermosetting resin. Heat resistance and electrical insulation. And since the resin composition before shaping | molding is liquid at normal temperature, shaping | molding by pouring is possible and it can be made into a free shape from being excellent in workability | operativity.

  However, the radiation scene of TEPCO's Fukushima Daiichi Nuclear Power Station, which has a specific gravity of more than 3 because extremely high radiation (γ-rays) is generated at the accident site, especially in the reactor building and turbine building and surrounding areas. Then, it is difficult to prevent exposure unless the molded product has a considerably large thickness. Moreover, it is not possible to use radiation shielding materials with a considerably large thickness at the accident site of the Fukushima nuclear power plant where the debris etc. are scattered and the radiation shielding material installation area and the work area for installing the radiation shielding material are limited. In addition to being difficult to secure in terms of space, it is not realistic in terms of construction work.

  Furthermore, in the technique described in Patent Document 1, for the purpose of providing a radiation shielding material having higher radiation shielding properties, if a resin is filled with a higher density of inorganic substance, a resin composition is obtained. It becomes a high viscosity and loses fluidity, and the desired radiation shielding resin molded product cannot be molded.

As described above, no radiation shielding material having excellent radiation shielding properties exceeding a specific gravity of 4 g / cm ³ has been provided so far, but for the purpose of preventing the human body from being exposed to strong γ rays, such as accident sites at the Fukushima nuclear power plant. There is a demand in the market for the development of a radiation shielding material with a radiation shielding resin composition that has higher and better γ-ray shielding properties and good workability at room temperature.
In addition, some reactors that are out of operation are expected to be dismantled toward the decommissioning in the future, so there is an increasing demand for radiation shielding materials with excellent radiation shielding function with smaller thickness. It is in.

JP-A-6-180389

  The present invention has been made in view of the above circumstances, and has a radiation shielding resin composition having excellent radiation shielding properties exceeding a specific gravity of 4 and good workability at room temperature, and the radiation shielding resin. A two-pack type radiation shielding resin material used to obtain a composition, and a radiation shielding resin molding such as a panel, block, sheet, or radioactive waste container molded using the radiation shielding resin composition. The purpose is to provide.

The resin composition for radiation shielding according to the present invention is an epoxy resin composition containing at least a liquid epoxy resin, a curing agent thereof, and a radiation shielding material, wherein the epoxy resin and the curing agent are mixed in the resin. The tungsten powder in the particle size range of at least 1.5 μm to 16 μm, preferably 4 μm to 8 μm, as the radiation shielding material is an amount that does not lose the fluidity of the mixture at room temperature, and the specific gravity is 4 g. It is characterized by being blended so as to be not less than / cm ³ .

  That is, according to the present invention, as described above, simply selecting a high-density inorganic material having a higher specific gravity as a radiation shielding material and filling the resin more in the resin based on the common general technical knowledge. In addition, there is a problem with workability that the viscosity of the resin composition increases and the fluidity is lost as the filling amount of the high-density inorganic substance increases, and as a result, the conventional product whose specific gravity exceeds 3 or more. The present inventors have intensively studied based on the problem that a radiation shielding resin composition having excellent radiation shielding properties as compared with the above cannot be obtained.

  As a result, the present invention uses a high-density inorganic substance having a large specific gravity and a predetermined particle size to suppress an increase in the viscosity of the resin composition accompanying an increase in the filling amount of the high-density inorganic substance. It has been found that a resin composition having a high specific gravity having excellent radiation shielding properties as compared with conventional products can be provided by using a density inorganic substance in an amount that does not lose the fluidity of the mixture at room temperature. Specifically, the present inventors have found that tungsten powder is selected as the high-density inorganic substance, and the particle size thereof is preferably in the particle size range of 1.5 μm to 16 μm.

  In the radiation shielding resin composition of the present invention, the tungsten powder preferably includes coarse particles in a particle size range of 10 μm to 40 μm together with fine particles in a particle size range of 4 μm to 8 μm. When tungsten powders having different particle diameters are used in this way, it is desirable that the tungsten powder is a mixture of fine particles and coarse particles in a weight ratio of approximately 3: 1.

  In the radiation shielding resin composition of the present invention, the epoxy resin is preferably a bisphenol liquid resin. When such a bisphenol liquid resin is used, the epoxy resin is 2,2-bis ( 4-hydroxyphenyl) propane type epoxy resin is desirable.

  In the radiation shielding resin composition of the present invention, the epoxy resin preferably contains a diluent.

  In the radiation shielding resin composition of the present invention, the curing agent may be one or more selected from the group consisting of aliphatic amines, alicyclic amines, heterocyclic amines, polyamidoamines, and modified products thereof. can do.

  Moreover, in the resin composition for radiation shielding of this invention, it is good to further contain a silane coupling agent. That is, the silane coupling agent can be used by replacing a part of the resin component composed of an epoxy resin and a curing agent.

  Moreover, in the resin composition for radiation shielding of this invention, it is good to further contain an alkanolamine. That is, the alkanolamine can be used by replacing a part of the resin component composed of an epoxy resin and a curing agent, similar to the silane coupling agent, and the resin component after adding the silane coupling agent. A part can be replaced and used.

  Moreover, in the resin composition for radiation shielding of this invention, it is good to further contain an antifoamer.

  Moreover, in the resin composition for radiation shielding of this invention, it is good to further contain a flexibility imparting agent.

  In addition, the radiation shielding resin material of the present invention includes a liquid A mainly composed of an epoxy resin and a liquid B mainly composed of a curing agent for obtaining any of the above-described radiation shielding resin compositions. A radiation shielding material that is contained in a resin composition obtained by mixing the liquid A and the liquid B, the liquid A side and the liquid B side in advance. It is characterized in that it is divided and mixed.

  Furthermore, the radiation shielding resin molded product of the present invention is obtained by curing and molding any of the radiation shielding resin compositions described above into a predetermined shape, or by applying any of the radiation shielding resin compositions described above to the inner surface of the container. It is characterized by being coated and cured.

The resin composition for radiation shielding according to the present invention is not simply obtained by blending an inorganic material having a large specific gravity, which is already known as a radiation shielding material, into the resin, but a particle size range of at least 1.5 μm to 16 μm, desirably 4 μm. Tungsten powder in a particle size range of ˜8 μm is used as a radiation shielding material. Therefore, the tungsten powder in the resin can be blended so that the specific gravity is 4 g / cm ³ or more in an amount that does not lose the fluidity of the mixture at room temperature.

  Therefore, it is possible to provide a radiation shielding resin composition having excellent radiation shielding properties and good workability at room temperature. In addition, since metallic lead is not used, it can be made highly safe and desirable for the body and the environment. Furthermore, the radiation shielding material can be thinned (or thinned), and a limited space can be effectively utilized.

It is the schematic explaining the manufacturing method of the resin composition for radiation shielding which concerns on this invention. It is the schematic explaining the other manufacturing method of the resin composition for radiation shielding which concerns on this invention. It is a figure explaining the method to measure the shielding ability of the radiation shielding resin molding (shielding material) which hardened the resin composition for radiation shielding concerning this invention, (A) It shields between a radiation source and a measuring device. (B) A partial schematic diagram showing a measurement state when there is a shielding material having a total thickness of 6 mm between the radiation source and the measuring device, (C) It is a partial schematic diagram showing a measurement state when there is a shielding material having an overall thickness of 54 mm between the radiation source and the measurement apparatus. It is a figure which shows the relationship between the value layer (1 / valent layer) with respect to various gamma rays, and the thickness of the resin molding for radiation shielding (shielding material).

Hereinafter, an example of an embodiment in the present invention will be described.
The radiation shielding resin composition of the present invention (hereinafter sometimes simply referred to as “resin composition”) contains at least a liquid epoxy resin, a curing agent thereof, and a radiation shielding substance, and comprises an epoxy resin. The basic composition is that at least tungsten powder is blended as a radiation shielding substance in a resin in which a mixture of a resin and a curing agent is uniformly mixed, and the tungsten powder has a size within a specific particle size range. .

  Any epoxy resin may be used as long as it has a liquid state at room temperature and has two or more epoxy groups in one molecule. Examples of such an epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, alicyclic epoxy resin, heterocyclic epoxy resin, and glycidyl ester type epoxy. Resin, glycidylamine epoxy resin, bromine-containing epoxy resin, cyclohexyl ring-containing epoxy resin, aliphatic epoxy resin such as propylene glycol diglycidyl ether, urethane-modified epoxy resin, and the like. May be used.

In the present invention, the epoxy resin is desirably bisphenol type among these. Specifically, 2,2-bis (4-hydroxyphenyl) propane type epoxy resin (bisphenol A type epoxy resin) is desirable.
Here, the 2,2-bis (4-hydroxyphenyl) propane-based epoxy resin refers to an epoxy resin derived from bisphenol A using bisphenol A as a raw material.

This epoxy resin is standard as an epoxy resin for γ-ray shielding materials, and has high versatility and supply stability as well as high physical properties and stability of a cured product.
Among the bisphenol-type epoxy resins, 2,2-bis (4-hydroxyphenyl) propane-based epoxy resins have a gentle curing reaction even if they are blended in large quantities, so that the pot life is increased and the work becomes easier. Easy to do. In other words, the pot life of the epoxy resin becomes shorter in proportion to the temperature, and becomes extremely short when the quantity of epoxy resin and curing agent added at once increases, and when it exceeds a certain amount, the reaction proceeds explosively and is controlled. Can not do. Therefore, it is important to select an epoxy resin that does not cause an explosion reaction even under a condition where a large amount is blended in order to obtain an epoxy resin composition of several kg to several hundred kg. In addition, it is important to select a curing agent that causes a mild reaction in consideration of the epoxy resin also in the curing agent described later.

  The epoxy resin may contain a diluent for adjusting the viscosity. That is, in the case of a bisphenol A type epoxy resin, the viscosity is as high as 12,000 to 15,000 mPa · s at 25 ° C., for example, when blended with a high viscosity curing agent such as polyamide, the viscosity becomes very high and workability is increased. There is a problem. Therefore, it is desirable to adjust the viscosity to be suitable for work by using various diluents.

Diluents can be divided into non-reactive and reactive. The reactive diluent has an epoxy group in the molecule, and thus reacts with the curing agent to become a part of the cured product. On the other hand, solvents and plasticizers are generally used as non-reactive diluents.
Examples of reactive diluents include glycidyl ether compounds such as butyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether, and glycidyl ethers of aliphatic alcohols. In addition, examples of the non-reactive diluent include organic solvents such as benzyl alcohol, toluene, and methyl ethyl ketone (MEK).

  The diluent is not particularly limited as long as it can reduce the viscosity of the epoxy resin, whether it is a reactive diluent or a non-reactive diluent. However, in the case of a reactive diluent, the curing reaction may not be controlled when a large amount of epoxy resin is used, while in the case of a non-reactive diluent, the reactivity may be too low. Therefore, it is desirable to use a combination of reactive and non-reactive diluents as the diluent in the present invention. By using such a bifunctional diluent, the viscosity of the epoxy resin can be reduced, and even when a large amount of the epoxy resin is used, the curing reaction can be suppressed without reducing the reactivity.

  Further, for example, when a 2,2-bis (4-hydroxyphenyl) propane-based epoxy resin is used as the epoxy resin, the diluent has a slightly high viscosity when the added amount of the diluent is 10% by mass or less. On the other hand, if it is 20% by mass or more, physical properties (strength) are lowered. Therefore, it is desirable to contain 10-20 mass% with respect to 80-90 mass% of epoxy resins.

  In facilities such as the Fukushima nuclear power plant, γ rays and neutron rays are mixed as radiation to be shielded. In order to effectively obtain neutron shielding ability as well as γ ray shielding ability, structural elements such as halogen ions are used. An epoxy resin with relatively few impurities and a relatively high hydrogen content is advantageous. That is, since hydrogen atoms can be decelerated by colliding with neutrons, an epoxy resin with a high hydrogen content makes it possible to shield neutrons. Therefore, the radiation shielding material using the resin composition of the present invention can efficiently shield radiation in which γ rays and neutrons are mixed.

  The curing agent cures with the epoxy resin at room temperature (15 to 40 ° C.), usually gives a pot life of 10 minutes to several hours, and requires a curing time of several tens minutes to 10 days. And it is not particularly limited. Such a curing agent can be, for example, one or more selected from the group of aliphatic amines, alicyclic amines, heterocyclic amines, polyamide amines, and modified products thereof.

Since these curing agents can be cured at room temperature and can be kept in a liquid state at room temperature, work at a construction site is possible, and workability can be improved.
Therefore, for example, after constructing a double wall of concrete around a place where storage of waste having a relatively high radiation level is planned, the resin composition can be poured into the gap between the concrete walls on site. Thereby, even if a structural crack enters concrete for reasons such as uneven settlement of the ground, radiation shielding properties can be ensured.

  Examples of the aliphatic amine include ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, diethylaminopropylamine, hexamethylenediamine, polyoxyethylenediamine, and polyoxypropylenediamine.

  Examples of alicyclic amines include metacene diamine, isophorone diamine, metaxylene diamine, N-aminoethylpiperazine, 3,9-bis (3-aminopropyl) -2,4,8,10-tetraoxaspiro (5, 5) Undecane, bis (4-amino-3-methylhexyl) methane, bis (4-aminohexyl) methane, norbornenediamine, paraaminodicyclohexylamine, 1,2-diaminocyclohexane and the like.

  Examples of the heterocyclic amine include 1,4-diazabicyclo [2.2.2] octane, 1,8-diazabicyclo [5.4.0] undecene-7, bis (2-morpholinoethyl) ether, and the like. it can.

  Examples of the polyamidoamine include those produced by a condensation reaction between a synthetic dimer acid and a polyamine such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and xylylenediamine.

  The blending amount of the room temperature curing type epoxy resin curing agent is appropriately selected depending on the type of curing agent to be used, but is usually 10 to 200 parts by weight, preferably 20 to 100 parts by weight with respect to 100 parts by weight of the epoxy resin. Mix parts by weight.

  In the present invention, a curing accelerator can be used for adjusting the curing rate. The curing accelerator is not particularly limited as long as it is usually used as a curing accelerator for epoxy resins, and imidazoles, tertiary amines, phenols and the like can be used.

Tungsten (W) as a radiation shielding material has a large specific gravity of 19.25 g / cm ³ and is known as one of γ-ray shielding metals. In the present invention, tungsten powder has a specific particle size range of 1 The amount of the mixture is blended in such a range that the fluidity of the mixture is not lost at room temperature so as to have a size of 0.5 μm to 16 μm and a specific gravity of 4 g / cm ³ or more.

In the present invention, the tungsten powder is preferably in the particle size range of 4 μm to 8 μm because the density of the cured resin can be increased while suppressing the viscosity of the resin composition from increasing. . That is, if the tungsten powder is too fine, the oil absorption is high and the viscosity of the resin composition is increased, and it is difficult to increase the density of the cured resin.
Therefore, by using such a tungsten powder having a particle size range of 4 μm to 8 μm, a cured product having a specific gravity of 4 to 7 g / cm ^{3 or} more can be obtained without excessively increasing the viscosity.

In the present invention, the tungsten powder preferably contains coarse particles having a particle size in the range of 10 μm to 40 μm, together with fine particles having a size in the particle size range of 4 μm to 8 μm. In other words, only the fine particles of tungsten powder lose fluidity just by increasing the viscosity, but by using the coarse particles together with the fine particles of tungsten powder, the tungsten powder flows in a finely packed state. It is possible to improve the properties, and to mix many tungsten powders while keeping the viscosity of the mixture low.
Therefore, by using the coarse-grained tungsten powder having a size in the range of 10 μm to 40 μm in this way, the flowability is higher than in the case of using only the fine-grained tungsten powder in the range of 4 μm to 8 μm. Thus, an increase in the viscosity of the resin composition can be suppressed and more tungsten powder can be blended.

Further, the tungsten powder is more desirable when the coarse particles are used together with the fine particles as described above, and the weight ratio of the fine particles to the coarse particles is approximately 3: 1.
That is, it has been found that the viscosity of the mixture can be made the lowest by setting such a blending ratio.

  In the present invention, for example, as shown in FIG. 1, after a liquid epoxy resin 1 as a main agent and its curing agent 2 are uniformly mixed to obtain a mixture 10, a tungsten powder having a predetermined size as a radiation shielding substance is obtained. 3 can be blended and further kneaded to produce the radiation shielding resin composition 20.

  Further, in the present invention, for example, as shown in FIG. 2, tungsten powder 3 (3a, 3b) having a predetermined size is distributed and mixed into the liquid epoxy resin 1 as the main agent and the curing agent 2 and mixed and kneaded. Then, after obtaining a tungsten powder-containing liquid epoxy resin (liquid A) 11 and a tungsten powder-containing curing agent resin (liquid B) 12, the radiation shielding resin composition 20 can also be produced by uniformly mixing them. Can do.

That is, in this manufacturing method, a radiation shielding resin material (A liquid) 11 containing tungsten powder containing epoxy resin as a main component and a tungsten powder containing radiation shielding resin material (liquid B) containing a curing agent as a main component. ) 12 is prepared in advance as a two-pack type radiation shielding resin material, and these are mixed at a desired location at a desired time to obtain a radiation shielding resin molded product.
In the case of this production method, tungsten powder can be preliminarily kneaded in the resin without involving a curing reaction between the epoxy resin and its curing agent, which is convenient when producing a radiation shielding resin molded product in the field. It is.

Since the resin composition for radiation shielding as described above can have fluidity at normal temperature, it can be poured at a construction site and workability is improved. In addition, since metallic lead is not used, it can be made highly safe and desirable for health and the environment.
Further, the cured product obtained by curing the resin composition has a specific gravity of 4 g / cm ³ or more, and therefore has a higher radiation shielding ability than a conventional radiation shielding material having a specific gravity of 3 or more. it can. Therefore, when the same radiation shielding capability is provided, the radiation shielding material can be thinned (or thinned), and a limited space can be effectively utilized.

  The radiation shielding resin composition of the present invention essentially comprises the above-described liquid epoxy resin, curing agent, and radiation shielding material, and further contains silane coupling agents, alkanolamines, antifoaming agents, and the like. Thus, the workability due to the decrease in viscosity, the radiation shielding ability, and the physical properties can be made more desirable.

  The silane coupling agent can improve the wettability of the surface of the inorganic material, improve the familiarity with the organic material (epoxy resin and curing agent), and improve the adhesion. That is, the silane coupling agent can improve the dispersibility at the time of mixing in the composite of the resin and the radiation shielding material. As such a silane coupling agent, it can be set as 1 type, or 2 or more types selected from the epoxy silane coupling agent, the aminosilane coupling agent, etc., for example.

In this way, the silane coupling agent reduces the viscosity of the mixture during the production of the resin composition and enables further blending of radiation shielding materials without affecting workability, so bending strength, tensile strength, compression Physical properties such as strength can be improved.
Therefore, by replacing a part of the resin with a silane coupling agent, a radiation shielding resin composition excellent in workability and excellent in radiation shielding ability can be obtained.

  Moreover, it is desirable that the silane coupling agent is replaced and contained within a range of 20% by mass or less of the resin content. That is, when the replacement rate of the silane coupling agent approaches 25% by mass of the resin content, the cured product tends to be hard and brittle, and the surface is clouded. Therefore, by setting the above range, the physical properties (balance between hardness and brittleness) and the appearance (the surface is not cloudy) are improved.

Alkanolamines, like silane coupling agents, improve the wettability of the surface of the inorganic material, so that the viscosity can be reduced to improve workability and improve physical properties. Therefore, by using together with the silane coupling agent, that is, by replacing a part of the remaining resin after adding the silane coupling agent with an alkanolamine which is a secondary or tertiary amine, workability is good. A resin composition for radiation shielding excellent in radiation shielding ability can be obtained.
As such alkanolamines, for example, one or more selected from diethanolamine, triethanolamine, diisopropanolamine and the like can be used.

  Moreover, it is desirable that alkanolamine is contained by replacing 6 to 7% by mass of the remaining resin after blending the silane coupling agent. By replacing the alkanolamine within this range, it can have good fluidity at room temperature.

  It is desirable that the antifoaming agent is further included because it can prevent bubbles in the resin composition and prevent the radiation shielding ability and physical properties of the cured product from being deteriorated. That is, when bubbles exist in the final cured product (resin molded product for radiation shielding), a decrease in specific gravity (density) directly linked to the γ-ray shielding ability occurs. Therefore, immediately after mixing the epoxy resin and the curing agent, the resin mixture needs to be defoamed under vacuum, but at this time, a large difference occurs in the defoaming time depending on the presence or absence of the defoaming agent. Therefore, it is desirable to further include an antifoaming agent.

  However, the antifoaming agent is added for the purpose of defoaming the foam involved when mixing the materials constituting the resin composition such as an epoxy resin and a curing agent. Care must be taken because it may adversely affect the properties (for example, bending strength) of the material and may cause stickiness to remain on the surface of the cured product, resulting in undesirable results.

  Each radiation shielding resin composition configured as described above can be a radiation shielding material that is cured and molded into a predetermined shape such as a panel or a block. Moreover, the resin composition for radiation shielding can also be used as a radioactive waste container by coating and curing the inner surface of a metal container or the like as a lining material.

The radiation shielding resin composition of the present invention may contain a flexibility imparting agent. That is, since the resin composition contains a flexibility imparting agent, the cured resin product becomes flexible, so that the radiation shielding resin composition having various modes can be molded.
Examples of such flexibility-imparting agents include non-reactive materials such as coumarone resin and monoamines such as oleylamine.

  Each of the radiation shielding resin moldings formed by applying the flexibility-imparting agent as described above is soft and easily elastically deformable and can be bent, so that a sheet body having a desired thickness can be obtained. it can. Therefore, by forming this sheet body into protective equipment such as outerwear, work clothes such as pants, shoes, gloves, etc., engaged in work at sites with strong γ rays such as the accident site of the Fukushima nuclear power plant, Therefore, a radiation shielding material having a movable range can be provided.

Next, in order to describe the resin composition for radiation shielding according to the present invention in more detail, examples will be shown and described specifically. The embodiments described here are examples of the present invention, and the present invention is not limited to these embodiments.
[Selection of particle size of tungsten powder]
First, in order to confirm that it is desirable for workability at room temperature to use tungsten powder having a particle size of 1.5 μm to 16 μm as a radiation shielding substance (inorganic material), it is blended in the resin. The fluidity when changing the particle size of the tungsten powder was evaluated.

<Examples 1-5>
Specifically, in a resin in which a liquid epoxy resin and its curing agent are uniformly mixed, a tungsten powder having a size (average particle size) of 0.6 μm or more and less than 1.5 μm (Example 1), 1 5 μm or more and less than 4 μm (Example 2), 4 μm or more and less than 8 μm (Example 3), 8 μm or more and less than 16 μm (Example 4), 10 μm or more and less than 40 μm (Example 5) ), Respectively, to prepare a resin composition, and the fluidity of the resin composition was evaluated.

  This fluidity is evaluated by placing the resin composition in a paper cup, making the paper cup slant at about 25 ° C., and letting the resin composition flow out, and after 30 seconds, the remaining amount of the resin composition in the paper cup is within 10%. The case of “A” was designated as “A”. Furthermore, after 30 seconds (after 1 minute in total), the case where the remaining amount of the resin composition in the paper cup was within 10% was designated as “B”, while the case where the remaining amount was 10% or more was designated as “C”. The results are shown in [Table 1] below.

The liquid epoxy resin used in Examples 1 to 5 is a low viscosity bisphenol A type epoxy resin (bisphenol A &#8212; epichlorohydrin polymer) “YD-118T” manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., and the curing agent is The polyamide amine “G625A” manufactured by Nippon Steel & Sumikin Chemical Co., Ltd. was used.
Further, the tungsten powders are all manufactured by Nippon Shin Metals Co., Ltd. In Example 1, “tungsten W-1KD (0.6 to 0.99 μm)” and “tungsten W-2KD (1.0 to 1.49 μm)”. In Example 2, in which “Tungsten W-3KD (1.50 to 1.99 μm)” and “Tungsten W-4KD (2.0 to 3.99 μm)” were mixed in half. In Example 3, “tungsten W-5KD (4.00 to 7.99 μm)” is used. In Example 4, “tungsten W-6 (8.0 to 16.0 μm)” is used. In Example 5, “tungsten is used. W-L (10.0-40.0 μm) ”was used.

  From the results of [Table 1], if a tungsten powder having a particle size range of 1.5 μm to 16 μm, which is not too small and is not too large and has an appropriate size, is used as the radiation shielding material. It can be seen that the workability at normal temperature is good and the workability at normal temperature is good. In particular, the use of a material having a particle size in the range of 4 to 8 μm is desirable.

[Confirmation of compounding amount of tungsten powder]
Next, using tungsten powder having a particle size range of 4 μm to 8 μm, which is a desirable size, as a radiation shielding material, it was confirmed how much the specific gravity can be increased without impairing workability at room temperature.

<Examples 6 to 9>
Specifically, a resin composition is manufactured by changing the blending amount of tungsten powder in a particle size range of 4 μm to 8 μm in a resin in which a liquid epoxy resin and its curing agent are uniformly mixed. The specific gravity of the cured product was measured. In addition, the fluidity of the resin composition was also evaluated. Furthermore, an appropriate amount of an antifoaming agent was added, and the defoaming property was also evaluated.

  Evaluation of the defoaming property is that when about 50 ml of resin mixture is put in a 200 ml resin cup with a scale, and this is left in the vacuum chamber, the inside of the chamber is depressurized by a vacuum pump to expand. The height of foaming (swelling condition) of the resin mixture was visually determined with reference to the scale attached to the resin cup. At this time, when the volume expansion is 1.2 times or less, “◎” mark, when the volume expansion is 1.2 to 1.5 times, “◯” mark, 1.5-2. When the bubble breaks within 0 times, “○ to △” mark, when the bubble breaks within 2.0 to 3.0 times, “△” mark, when the bubbles do not break unless it is 3.0 times or more An “x” mark was given. The results are also shown in the following [Table 2].

In addition, the epoxy resin and hardening | curing agent which were used in Examples 6-9 are the same as what was used in Examples 1-5. The tungsten powder is the same as that used in Example 3.
Further, as the antifoaming agent, a solution type silicone antifoaming agent “KS-603” manufactured by Shin-Etsu Chemical Co., Ltd. was used.

＊実施例９の消泡剤量は2.15とのご指示ですが、小数点以下の位を合わせました。

* The amount of antifoaming agent in Example 9 is 2.15, but the decimal places are combined.

From the results of [Table 2], by using tungsten powder having a particle size range of 4 μm to 8 μm as a radiation shielding material, workability at room temperature is good, and conventional radiation shielding materials (3 g / cm It was confirmed that the resin composition obtained was a radiation shielding resin molded product (cured product) having a much higher specific gravity than ³ ). Moreover, even when the blending amount of the tungsten powder is increased to 280 parts, it is confirmed that the fluidity is not impaired and the workability at normal temperature is good and a resin molded product (cured product) having a specific gravity of slightly over 7 g / cm ³ is obtained. .
However, when the blending amount of the tungsten powder is increased to 400 parts, the specific gravity of the resin molded product can be reduced to less than 9 g / cm ³ , but the resin composition has a very high viscosity and loses fluidity at room temperature. It has become.

[Confirmation of combination effect of tungsten powders with different particle sizes]
Next, it was confirmed that a resin composition with improved workability was obtained by using two types of tungsten powders having different particle sizes.

<Examples 10 to 13>
Specifically, in a resin in which a liquid epoxy resin and its curing agent are uniformly mixed, a fine particle of tungsten powder having a particle size range of 4 μm to 8 μm and a particle size range of 10 μm to 40 μm. A mixture of coarse particles of a certain tungsten powder, wherein the fine particles and the coarse particles have a mixing ratio of 1: 1 (Example 10), and the mixing ratio of 2: 1 (Example 11), a resin composition was manufactured as a mixture ratio of 3: 1 (Example 12) and a mixture ratio of 4: 1 (Example 13), and the flow Sexuality was evaluated. In addition, the specific gravity of the resin molded product (cured product) was also measured. Furthermore, an appropriate amount of an antifoaming agent was added, and the defoaming property was also evaluated. The results are also shown in the following [Table 3].

  Further, in order to clarify the effect of using two types of tungsten powders having different particle sizes, a desirable result is obtained when using tungsten powders having a particle size range of 4 μm to 8 μm as a comparison target. The results of Example 8 obtained are also shown in [Table 3].

In addition, the epoxy resin and hardening | curing agent which were used in Examples 10-13 are the same as what was used in Examples 1-5. The tungsten powder is the same as that used in Example 3 for the fine particles and that used in Example 5 for the coarse particles.
In addition, an appropriate amount of an antifoaming agent is added to each resin composition, and the antifoaming agent is the same as that used in Examples 6-9.

From the results of [Table 3], when tungsten powders having different sizes are blended in a resin in which a liquid epoxy resin and its curing agent are uniformly mixed, tungsten powders having a particle size range of 4 μm to 8 μm are used. The flowability of the mixture is improved and the workability at room temperature is better than in Example 8 where the desired result was obtained, and the radiation shielding resin molding having a much higher specific gravity than the conventional radiation shielding material is molded. It was confirmed that the resin composition can be used.
Further, the tungsten powder is a mixture of fine particles having a particle size in the range of 4 μm to 8 μm and coarse particles having a particle size in the range of 10 μm to 40 μm at a weight ratio of approximately 3: 1. As a result, it was confirmed that the viscosity of the mixture (epoxy resin composition) can be made lower than when only the fine particles of tungsten powder are used, and that the workability is improved. In addition, a resin composition in which the specific gravity of the resin molding is further increased can be obtained.

[Confirmation of combination effect of silane coupling agent]
Next, it was confirmed that a resin composition with improved workability was obtained by using a silane coupling agent.

<Example 14>
Specifically, the liquid epoxy resin and a part of its curing agent are replaced with a silane coupling agent, and a resin composition is prepared by blending the same amounts of tungsten powders of different sizes in a resin that is uniformly mixed. The fluidity was evaluated. At this time, the tungsten powder has a tungsten powder (referred to as “tungsten powder A”) having a particle size range of 4 μm to 8 μm and a tungsten powder (“tungsten powder” having a particle size range of 8 μm to 16 μm. B ”). In addition, the specific gravity of the resin molded product (cured product) was also measured. Furthermore, an appropriate amount of an antifoaming agent was added, and the defoaming property was also evaluated. The results are also shown in the following [Table 4].

  In addition, in order to confirm the combination effect of the silane coupling agent, when a tungsten powder having a size in a particle size range of 4 μm to 8 μm is used as a comparison object without replacing part of the resin with the silane coupling agent The results of Example 8 in which desirable results were obtained are also shown in [Table 4].

The epoxy resin and the curing agent used in Examples 14 and 15 are the same as those used in Examples 1-5.
The tungsten powder used in Example 14 is the same as that used in Example 3, and the tungsten powder used in Example 15 is the same as that used in Example 4.
Furthermore, the silane coupling agent “KBM-403” manufactured by Shin-Etsu Silicone Co., Ltd. was used as the silane coupling agent.

  From the results of [Table 4], by adding a silane coupling agent to a resin in which a liquid epoxy resin and its curing agent are uniformly mixed, tungsten powder having a particle size range of 4 μm to 8 μm was used. It was confirmed that the fluidity of the mixture was improved and the workability was better than in Example 8 where sometimes desirable results were obtained. Moreover, not only the tungsten powder having a particle size range of 4 μm to 8 μm but also the tungsten powder having a particle size range of 8 μm to 16 μm is used, the viscosity of the mixture is lowered. It was confirmed that the workability was good. Therefore, in the present invention, it can be seen that tungsten powder having a size in a particle size range of 4 μm to 16 μm can be used.

[Confirmation of compounding amount of silane coupling agent]
Next, when a silane coupling agent was blended using tungsten powder having a particle size range of 4 μm to 8 μm, which is a desirable size, as a radiation shielding material, it was confirmed how much blending amount was desirable.

<Examples 16 to 19>
Specifically, a resin composition in which a liquid epoxy resin and a part of its curing agent are replaced with a silane coupling agent and a tungsten powder having a particle size range of 4 μm to 8 μm is blended in a resin mixed uniformly. In order to confirm the effect of the amount of the silane coupling agent added, the flowability of the resin composition produced by changing the replacement ratio of the resin to the silane coupling agent and the resin molded product (cured product) ) Was evaluated for strength. In this example, the resin component was replaced with a silane coupling agent with a replacement rate of 10% by mass or less (Example 16: the replacement rate was 7.1% by mass), and 10% by mass of the same ( Example 17: Replacement rate is 11.1% by mass), 20% by mass (Example 18), and 20% by mass or more (Example 19: Replacement rate is 25.0% by mass) Evaluation was performed.

In addition, the strength of the resin molded product (cured product) was evaluated by using the Shore A hardness meter (WR-204A) manufactured by Nishitokyo Seimitsu Co., Ltd. for the hardness of the cured product after 2 weeks at room temperature (about 25 ° C.). The “hardness”, the remaining state of the needle trace after the measurement, and the presence or absence of cracks from the needle trace were confirmed. Specifically, “A” indicates that the needle trace does not remain on the surface when the hardness is 98 or more, “B” indicates that the hardness is 98 or less but no needle trace remains, and the needle trace remains if the hardness is 98 or greater. The case was “C”, the hardness was 98 or less and the needle trace remained “D”, and the hardness was 98 or less and the needle trace was “E”. The results are also shown in [Table 5] below.
In addition, the specific gravity of the resin molded product (cured product) was measured. Furthermore, an appropriate amount of an antifoaming agent was added, and the defoaming property was also evaluated. The results are also shown in the following [Table 5].

  At this time, as one of the data of the replacement of the resin portion with the silane coupling agent being 10% by mass or less, the fluidity of the mixture is improved and the workability is improved by combining the silane coupling agent. The results of Example 14 (replacement rate: 3.4% by mass) whose effect was confirmed are also shown in [Table 5].

  In addition, the epoxy resin and the curing agent used in Examples 16 to 19 are the same as those used in Examples 1 to 5, and the silane coupling agent is the same as that used in Example 14. Moreover, the tungsten powder is the same as that used in Example 3, and the antifoaming agent added to the resin composition is the same as that used in Examples 6-9.

  From the results of [Table 5], when a part of the resin is replaced with a silane coupling agent, the resin composition has excellent fluidity, but 25% by mass of the resin is silane coupling. If it is replaced with an agent, the fluidity is improved and the specific gravity is slightly increased, but the curability is extremely slow and the cured product becomes soft and brittle. Therefore, when a part of the resin is replaced with a silane coupling agent in a range of 20% by mass or less, the workability at normal temperature is good and the specific gravity of the resin molded product (cured product) is further increased. It can be seen that this is desirable.

[Confirmation of compounding amount of tungsten powder after combining silane coupling agent]
Next, when tungsten powder with a particle size range of 4 μm to 8 μm, which is a desirable size, is used as a radiation shielding material and a predetermined amount of silane coupling agent is blended, how much specific gravity can be achieved without impairing workability at room temperature. Confirmed that it can be enlarged.

<Examples 20 to 24>
Specifically, as a part of the liquid epoxy resin and its curing agent, tungsten powder having a particle size range of 4 μm to 8 μm in a resin mixed uniformly by replacing 10% by mass with a silane coupling agent. The resin composition was produced by changing the blending amount of Examples (Examples 20 to 23), and the fluidity was evaluated and the specific gravity of the cured product was measured. In addition, an appropriate amount of an antifoaming agent was added, and the defoaming property was also evaluated. The results are also shown in the following [Table 6].

  In addition, a resin composition in which the replacement ratio of the silane coupling agent was 20% by mass, and more tungsten powder having a particle size range of 4 μm to 8 μm in the resin was blended was produced (Example 24). The same evaluation and measurement as in Examples 20 to 23 were performed, and the results are also shown in the following [Table 6].

  In addition, in order to clarify that the specific gravity can be further increased when a predetermined amount of the silane coupling agent is blended, as a comparison object, a replacement ratio which is a desirable blending amount of the silane coupling agent is 10 mass% (11. 1), the results of Example 17 are also shown in [Table 6].

  In addition, the epoxy resin and the curing agent used in Examples 20 to 24 are the same as those used in Examples 1 to 5, and the silane coupling agent is the same as that used in Example 14. Moreover, the tungsten powder is the same as that used in Example 3, and the antifoaming agent added to the resin composition is the same as that used in Examples 6-9.

From the results of [Table 6], when a silane coupling agent is added to a resin in which a liquid epoxy resin and its curing agent are uniformly mixed, the replacement rate of the silane coupling agent is 10% by mass (11.1% by mass). It was confirmed that the workability at normal temperature was good, and up to 440 parts of tungsten powder could be blended to obtain a resin molded product (cured product) having a specific gravity of slightly over 9 g / cm ³ .
However, when the blending amount of the tungsten powder is increased to 620 parts, even if the replacement rate of the silane coupling agent is increased, a resin composition having a very high viscosity is obtained, and the fluidity is lost at room temperature.

[Confirmation of effect of coupling agent when tungsten powders with different particle sizes are combined]
Next, even when two types of tungsten powders having different particle diameters were used, it was confirmed that a resin composition having further improved workability can be obtained by using a silane coupling agent.

<Examples 25 and 26>
Specifically, when two types of tungsten powder having different particle diameters are used, a liquid epoxy resin and a resin composition in which a part of the curing agent is replaced with a silane coupling agent (Example 25), and a liquid epoxy resin When a part of the curing agent is replaced with a silane coupling agent, a resin composition (Example 26) using two kinds of tungsten powders having different particle diameters as tungsten powder is produced, and the fluidity of each is evaluated. Went. In this embodiment, two types of tungsten powders having different particle sizes use fine particles having a particle size range of 4 μm to 8 μm and coarse particles having a particle size range of 10 μm to 40 μm. These fine particles and coarse particles were mixed at a weight ratio of 3: 1.
In addition, the specific gravity of the resin molded product (cured product) was measured. Furthermore, an appropriate amount of an antifoaming agent was added, and the defoaming property was also evaluated. The results are shown in [Table 7] below.

  Moreover, in order to clarify the improvement effect of replacing a part of the resin with the silane coupling agent, as a comparison object with respect to Example 25, a part of the resin was not replaced with the silane coupling agent. As a comparison object with respect to the result of Example 12 in which desirable results were obtained when two types of tungsten powders having different diameters were used, and Example 26, tungsten powder was one type (4 μm to 8 μm in a desired size). The results of Example 24 in which the desired results were obtained by blending the silane coupling agent were also shown in [Table 7].

The epoxy resin and the curing agent used in Examples 25 and 26 are the same as those used in Examples 1-5. The tungsten powder is the same as that used in Example 3 for the fine particles, that used in Example 4 for the small particles, and that used in Example 5 for the coarse particles.
In addition, an appropriate amount of an antifoaming agent is added to each resin composition, and the antifoaming agent is the same as that used in Examples 6-9.

From the results of [Table 7], when two types of tungsten powders having different particle sizes are used, by replacing a part of the liquid epoxy resin and its curing agent with a silane coupling agent, workability at room temperature is good, Although a part of the resin is not replaced by a silane coupling agent, a radiation shielding resin molded product having a higher specific gravity than Example 12 that obtained desirable results when two types of tungsten powders having different particle diameters were used. It confirmed that it could be set as the resin composition which can obtain (cured material).
In addition, when replacing the liquid epoxy resin and part of its curing agent with a silane coupling agent, the amount of tungsten powder is increased to 620 parts by using two types of tungsten powder having different particle sizes. However, tungsten powder is one type (desired particle size range of 4 μm to 8 μm), but the fluidity is higher than that of Example 24 in which a desirable result was obtained by adding a silane coupling agent. It was confirmed that the resin composition can be obtained without losing (good workability at normal temperature) and capable of obtaining a radiation shielding resin molded product (cured product) having a larger specific gravity.

[Confirmation of combination effect of alkanolamine]
Next, it was confirmed that a resin composition with further improved workability was obtained by using two types of tungsten powders having different particle sizes as radiation shielding materials and using alkanolamine together with a silane coupling agent.

<Example 27>
Specifically, as a part of the liquid epoxy resin and its curing agent, 20% by mass is replaced with a silane coupling agent and an alkanolamine, and the particle size is 4 μm to 8 μm in a uniformly mixed resin. A fine composition of tungsten powder and a coarse powder of tungsten powder having a particle size range of 10 μm to 40 μm were blended to produce a resin composition, and its fluidity was evaluated. In addition, the specific gravity of the resin molded product (cured product) was also measured. Furthermore, an appropriate amount of an antifoaming agent was added, and the defoaming property was also evaluated. The results are also shown in the following [Table 8].

  Moreover, in order to clarify the improvement effect of combining alkanolamines, the results of Example 25 described above in which a part of the resin was replaced with a silane coupling agent were also shown in Table 8 as a comparison target. It was.

  The epoxy resin and the curing agent used in Example 27 are the same as those used in Examples 1 to 5, and the silane coupling agent is the same as that used in Example 14. Further, the tungsten powder is the same as that used in Example 3 for the fine particles and the one used in Example 5 for the coarse particles, and the antifoaming agent added to the resin composition is as in Example 6. Same as used in ~ 9. As the alkanolamine, “diisopropanolamine” manufactured by Mitsui Chemical Fine Co., Ltd. was used.

From the results of [Table 8], by adding a silane coupling agent and an alkanolamine into a resin in which a liquid epoxy resin and its curing agent are uniformly mixed, the workability and defoaming property at room temperature are good, Radiation shielding resin molding (cured) having a large specific gravity approaching the specific gravity of metal lead (11.3 g / cm ³ ), which can be added in a larger amount than in Example 25 using only the silane coupling agent. It was confirmed that the resin composition can be obtained.

[Confirmation of effect of flexibility imparting agent]
Next, it was confirmed that a flexibility imparting agent could be further added.
<Examples 28 and 29>
Specifically, the same amount of tungsten powders of different sizes are blended in a resin in which a liquid epoxy resin, a curing agent thereof, and a coumarone resin as a flexibility imparting agent are uniformly mixed. Manufactured and evaluated for their fluidity. In the present example, a tungsten powder (referred to as “tungsten powder A”) having a particle size range of 4 μm to 8 μm (Example 28) and a particle size range of 8 μm to 16 μm are used. Evaluation was made on a product using a certain tungsten powder (referred to as “tungsten powder B”) (Example 29).

In addition, the specific gravity of the resin molded product (cured product) is also measured, and in order to confirm that the flexibility has been obtained, a cured product is created and the elongation rate is obtained to evaluate the flexibility. did. This elongation was measured according to JIS-K6911 using a test piece that had been cured at 25 ° C. for 7 days after a plate-like cured product having a length of 100 mm × width of 10 mm × thickness of 5 mm was prepared. The measurement conditions are gripping interval (L): 50 mm, pulling speed: 5 mm / min. From the elongation (ΔL) of the gripping interval until the test piece breaks (at the time of cutting), the elongation rate is calculated by the following calculation formula (1). Asked.
The results are shown in [Table 9] below.

  In addition, in order to clarify the effect of the flexibility imparting agent, as an object for comparison, the above-mentioned embodiment was confirmed that the fluidity of the mixture is improved and the workability is improved by combining the silane coupling agent. The results of 14 are also shown in [Table 9].

  The epoxy resin and the curing agent used in Examples 28 and 29 were the same as those used in Examples 1 to 5, and the coumarone resin was “Esclon L-5” manufactured by Nikko Chemical. However, the curing agent and coumarone resin can be blended in advance and used. The tungsten powder used in Example 28 is the same as that used in Example 3, and the tungsten powder used in Example 29 is the same as that used in Example 4. Further, an appropriate amount of antifoaming agent is added to each resin composition, and the antifoaming agent is the same as that used in Examples 6-9.

From the results of [Table 9], by adding a flexibility imparting agent to the resin, a silane coupling agent can be used even when tungsten powder having a single particle size (size: 4 μm to 8 μm) is used. When combined, the fluidity of the mixture was improved, and the effect of improving workability was confirmed. Thus, the cured product had a larger elongation rate than that of Example 14, and the cured product was given flexibility. I was able to confirm. Moreover, not only the tungsten powder having a particle size range of 4 μm to 8 μm but also the tungsten powder having a particle size range of 8 μm to 16 μm is used, the workability at room temperature is good. Further, it was possible to obtain a radiation shielding resin molded product (cured product) having a specific gravity greater than that of the conventional radiation shielding material (over 3 g / cm ³ ).
Therefore, in this invention, it turns out that the resin molded product for radiation shielding (hardened | cured material) which has flexibility is obtained using the tungsten powder which exists in a particle size range with a magnitude | size of 4 micrometers-16 micrometers.

[Confirmation of effect of flexibility imparting agent when tungsten powders with different particle sizes are combined]
Next, even when two types of tungsten powders having different particle diameters were used, it was confirmed that a resin molded product (cured product) having flexibility was obtained by blending a flexibility imparting agent.

<Examples 30 and 31>
Specifically, fine particles of tungsten powder in a particle size range of 4 μm to 8 μm in a resin in which a liquid epoxy resin, its curing agent, and coumarone resin as a flexibility imparting agent are uniformly mixed. And a coarse powdered body of tungsten powder having a particle size range of 10 μm to 40 μm in a ratio of 3: 1. The mixing ratio of epoxy resin and curing agent resin is 2: 1 (Example 30) and those having the same mixing ratio of 1: 1 (Example 31), resin compositions were produced and their fluidity was evaluated.

  In addition, the specific gravity of the resin molded product (cured product) is also measured, and in order to confirm that flexibility has been obtained, the resin molded product (cured product) is obtained by the same method as in Examples 30 and 31 above. The elongation of the cured product was determined to evaluate the flexibility. The results are shown in [Table 10] below.

Note that the epoxy resin, the curing agent, and the coumarone resin used in Examples 30 and 31 are all the same as those used in Examples 28 and 29. The tungsten powder is the same as that used in Example 3 for the fine particles and that used in Example 5 for the coarse particles.
In addition, an appropriate amount of an antifoaming agent is added to each resin composition, and the antifoaming agent is the same as that used in Examples 6-9.

From the results of [Table 10], when two kinds of tungsten powders having different particle diameters are blended, even if a flexibility imparting agent is blended in the resin, the workability at normal temperature is good, and the radiation shielding so far It was confirmed that a radiation shielding resin molded product (cured product) having a specific gravity greater than that of the material (over 3 g / cm ³ ) was obtained. Moreover, the radiation shielding resin molded product (cured product) provided with flexibility having a very large elongation rate by setting the blending ratio of the epoxy resin, the curing agent resin, and the coumarone resin to 1: 1: 1. I was able to get it.

[Confirmation of radiation (γ-ray) shielding ability]
Next, it was confirmed that the radiation shielding resin molded product (cured product) obtained by curing the radiation shielding resin composition of the present invention has sufficient radiation shielding ability to function as a radiation shielding material.
In this example, Example 12 (the desired result was obtained when two types of tungsten powder having different particle diameters were used), Example 14 (the desired result was obtained by combining the silane coupling agent) And radiation shielding resin composition described in Example 30 (in which two kinds of tungsten powders having different particle diameters are used and a flexibility imparting agent is blended in the resin) ) The shielding ability was evaluated.

  The shielding ability test was performed by preparing nine cured products having a length of 200 mm × width of 200 mm × thickness of 6 mm using the radiation shielding resin composition of Example 12 described above, and then curing at 25 ° C. for 2 weeks. Are used as test materials, and by combining these test materials as appropriate, shielding tests against radiation (γ-rays) with four types of thicknesses of 6 mm, 18 mm, 24 mm, and 54 mm as a whole are performed. It was. That is, when the thickness of the whole shielding material was 6 mm, one test material having a thickness of 6 mm was used. When the thickness was 18 mm, three test materials having a thickness of 6 mm were used. When the thickness was 24 mm, four test materials having a thickness of 6 mm were used. Furthermore, when the thickness was 54 mm, all nine test materials having a thickness of 6 mm were used.

  In addition, the shielding ability test uses a gamma ray measuring instrument S-3073 (1 inch φNaI scintillation detector) manufactured by Applied Koken Kogyo Co., Ltd., owned by the Tokyo Metropolitan Industrial Technology Research Center, an external organization. And using the radiation source owned by the center. This NaI scintillation detector detects the wavelength of luminescence generated when radiation (γ rays) enters the detector with a sodium iodide crystal detector. The radiation source is I) Cesium 137 radiation source (hereinafter referred to as “Cs137”), the radiation source intensity (nominal value) is 10 MBq (reference date: December 16, 2010), and II) Cobalt 60 The radiation source (hereinafter referred to as “Co60”) and the radiation source intensity (nominal value) are 10 MBq (reference date: December 16, 2010).

  As shown in FIG. 3, when the height T from the floor G is 1.2 m, the measurement method specifies the flight direction of the radiation (γ rays) emitted from the radiation source RS, and the flight is performed from other directions. When the distance D between the tip of the collimator C for shielding γ rays and the measuring instrument M is 250 mm (constant), and there is no sample (shielding material) S between them (see FIG. 3A), the sample ( The dose was measured for the case where the shielding material S was present. Further, in the case where the sample (shielding material) S is present between the radiation source RS and the measuring apparatus M, the thickness of the entire shielding material S is 6 mm (see FIG. 3B) and 18 mm, as described above. , 24 mm, and 54 mm (see FIG. 3C). Moreover, the measurement was performed 10 times at intervals of 30 seconds, and the shielding rate was obtained from the average value of the measured doses based on the following calculation formula (2). The results are shown in [Table 11] below. In addition, BG in the calculation formula (2) is a background (radiation from other than the measurement target) value.

  Moreover, based on the result of [Table 11] (obtained shielding rate), the valence layer for various γ rays was calculated based on the following calculation formula (3). The results are shown in [Table 12] and [FIG. 4] below.

From this [FIG. 4], the thickness of the shielding material for attenuating the dose based on the 1 / valent layer shown on the vertical axis can be seen from the horizontal axis. The thickness of the shielding material to be reduced by a factor of 1 can be seen from the horizontal axis, and the thickness of the shielding material to reduce the dose by a factor of 5 can be seen from the horizontal axis from the same 1/5 valence layer.
Therefore, from the result of [FIG. 4], in the case of γ rays by Cs137, the ½ valence layer (thickness that shields 50% of the dose) is about 11 mm, and the ½ valence layer (thickness that shields 80% of the dose) is It was confirmed that it was about 26 mm.
However, when the source is γ-rays with Co60, the ½ valence layer requires about 20 mm and the ½ valence layer requires about 48 mm, and it can be confirmed that the penetration force to the shielding material of the same source is high. It was.

  DESCRIPTION OF SYMBOLS 1 Epoxy resin (main ingredient), 2 Hardener, 3 (3a, 3b) Tungsten powder, 10 mixture, 11 Liquid epoxy resin containing tungsten powder (A liquid), 12 Radiation shielding resin material containing tungsten powder (liquid B), 20 Radiation shielding resin composition.

Claims (12)

An epoxy resin composition comprising at least a liquid epoxy resin, a curing agent thereof, and a radiation shielding material,
In the resin in which the epoxy resin and the curing agent are mixed, tungsten powder having a particle size range of at least 1.5 μm to 16 μm, preferably 4 μm to 8 μm, as the radiation shielding material, is a mixture at room temperature. A radiation shielding resin composition characterized in that the amount is in a range not losing fluidity and the specific gravity is 4 g / cm ³ or more.   The tungsten powder includes fine particles in a particle size range of 4 μm to 8 μm and coarse particles in a particle size range of 10 μm to 40 μm, and the fine particles and the coarse particles have a weight of approximately 3: 1. The radiation shielding resin composition according to claim 1, wherein the radiation shielding resin composition is blended in a ratio.   The radiation shielding resin composition according to claim 1, wherein the epoxy resin is a 2,2-bis (4-hydroxyphenyl) propane-based resin.   The said epoxy resin contains a diluent, The resin composition for radiation shielding of Claim 3 characterized by the above-mentioned.   5. The curing agent according to claim 1, wherein the curing agent is at least one selected from the group consisting of aliphatic amines, alicyclic amines, heterocyclic amines, polyamide amines, and modified products thereof. The radiation shielding resin composition according to claim 1.   The radiation shielding resin composition according to claim 1, further comprising a silane coupling agent.   The radiation shielding resin composition according to claim 6, further comprising alkanolamine.   The radiation shielding resin composition according to claim 1, further comprising an antifoaming agent.   The radiation shielding resin composition according to claim 1, further comprising a flexibility imparting agent. A liquid A mainly composed of an epoxy resin and a B liquid mainly composed of a curing agent for obtaining the radiation shielding resin composition according to any one of claims 1 to 9. A resin material,
A radiation shielding substance to be contained in a resin composition obtained by mixing the liquid A and the liquid B is preliminarily distributed and blended into the liquid A side and the liquid B side. Liquid-type radiation shielding resin material.   A radiation shielding material obtained by curing and molding the radiation shielding resin composition according to any one of claims 1 to 9 into a predetermined shape.   A radioactive waste container, wherein the radiation shielding resin composition according to any one of claims 1 to 9 is coated on an inner surface of a container and cured.

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