JP2013000006A - Method for radiation decontamination, and radiation absorbing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel method for radiation decontamination, particularly, a simple method for radiation decontamination which prevents agricultural crops from being contaminated with radioactive substance during cultivation, and a radiation absorbing material used for the method.SOLUTION: In the method, a resin molded article containing a fluorescent pigment having light conversion capability and absorbing an electromagnetic wave with a low wavelength including radiation and releasing an electromagnetic wave with a long wavelength, is used to absorb radiation, whereby radioactive contamination is removed. The resin molded article is formed of, for example, a sheet-like or net-like body, and agricultural crops during cultivation are covered with the sheet-like or net-like body, whereby the agricultural crops can be prevented from radiation contamination.

Description

  The present invention relates to a method for controlling radioactive contamination, and more particularly to a method for protecting crops from radioactive contamination during cultivation, and a radiation-absorbing material.

As a result of the Great East Japan Earthquake on March 11, 2011, the Fukushima Daiichi Nuclear Power Station was damaged. As a result, radioactive materials were scattered, and as a result, radioactive materials were detected from agricultural products such as vegetables, and the effects on the human body were affected. There is a situation that cannot be shipped due to concerns.
The detected radioactive materials are isotopes that have a very large influence on the human body, such as cesium 134, cesium 137, and iodine 131. These materials have a wavelength of about 10 pm or less, such as γ-rays, in the radiation. It generates extremely short electromagnetic waves.

  In view of such circumstances, in particular, when cultivating crops, it is a method that absorbs radiation generated from radioactive substances, particularly γ rays, and controls crops under cultivation from contamination of radioactive substances, and is a particularly simple method. However, there is nothing in the prior art.

  For example, in Patent Document 1, at least one surface of a fluororesin film containing a fine powder of cerium oxide and a silicon compound capable of maintaining ultraviolet absorption ability for a long period of time is modified by graft polymerization with a hydrophilic monomer or the like. Agricultural fluororesin films have been proposed. However, the agricultural fluororesin film is intended to absorb ultraviolet rays having a wavelength of 280 to 320 nm, and is not intended for radiation having an extremely short wavelength.

JP 2000-287559 A

  The present invention solves such problems, and a novel method for controlling radioactive contamination, and particularly, a simple method for controlling radioactive contamination so that agricultural products are not contaminated by radioactive substances during cultivation, and is used for the same. The purpose is to provide radiation-absorbing materials.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have developed a fluorescent radioactive agricultural material that has been invented and proposed by the present inventors and is extremely effective for promoting photosynthesis (Japanese Patent Laid-Open No. 2007-135583 and Japanese Patent Laid-Open No. 2007-13558). 2010-115193 gazette) has a property of absorbing or attenuating an electromagnetic wave having a very short wavelength such as radiation (hereinafter collectively referred to as absorptivity), and the present invention has been completed. .

That is, the present invention provides (1) Radioactive contamination control using a resin molded article that contains a fluorescent dye having light conversion performance and absorbs electromagnetic waves in a low wavelength region including radiation and emits electromagnetic waves in a long wavelength region. Is the method.
In the present invention, (2) the resin molded body is a sheet-like body or a net-like body, and the agricultural product being grown is covered with the sheet-like body and / or the net-like body to control the agricultural product from radioactive contamination. The radioactive contamination control method according to (1) above.

In the present invention, (3) the resin molded body is a sheet-like body or a net-like body, and at least a part of the roof portion and the wall portion is configured by the sheet-like body and / or the net-like body. It is a radioactive contamination control method as described in said (1) which cultivates an agricultural product in the inside and controls agricultural products from radioactive contamination.
In the present invention, (4) the resin molded body is a rigid plate-like body, and the crop is cultivated in a house in which at least a part of the roof portion and the wall portion is composed of the rigid plate-like body. It is a radioactive contamination control method as described in said (1) which controls from radioactive contamination.

Further, the present invention provides (5) the electromagnetic wave radiated from the resin molded body is 450 to 700 nm fluorescent light effective for promoting photosynthesis, according to any one of the above (1) to (4), This is a method for controlling radioactive contamination.
The present invention is also (6) the radioactive contamination control method according to any one of (1) to (5), wherein the fluorescent dye is a perylene dye.

In addition, the present invention is characterized by comprising (7) a resin molded article that contains a fluorescent dye having light conversion performance and that absorbs electromagnetic waves in a low wavelength region including radiation and emits electromagnetic waves in a long wavelength region. It is a radiation absorbing material.
The present invention also provides (8) the radiation-absorbing material as described in (7) above, wherein the fluorescent dye is a perylene dye.

Further, the present invention is (9) wherein the fluorescent dye absorbs an electromagnetic wave in a low wavelength region containing radiation and emits fluorescence in a wavelength region of 450 to 700 nm. It is a radiation absorbing material as described in 8).
In addition, the present invention is (10) the radiation-absorbing material according to any one of (7) to (9), wherein the resin molded body is a sheet-like body or a net-like body.

In addition, the present invention provides (11) the radiation-absorbing material according to any one of (7) to (9), wherein the resin molded body is a rigid plate-like body.
Moreover, this invention is (12) the crop cultivation material which consists of a radiation absorptive material in any one of said (7) thru | or (11).
Moreover, this invention is (13) crop cultivation material which consists of a house in which at least one part of a roof part and / or a wall part is comprised from the radiation absorptive material in any one of said (7) thru | or (11). It is.

According to the present invention, the resin molded body containing a fluorescent dye having a light converting ability, absorbing electromagnetic waves in a low wavelength region containing radiation and emitting electromagnetic waves in a long wavelength region has radiation absorbing ability. When the resin molded body is a sheet-like body or a net-like body, if these are used as agricultural product-growing materials so as to cover the crops, these materials absorb radiation and radioactively contaminate the crops being grown. Can be controlled from.
In addition, the fluorescence emitted by the resin molded body in the present invention has an effect of promoting the photosynthesis of agricultural products such as various vegetables, fruits and flowers. It is particularly preferable for promoting photosynthesis that the electromagnetic wave radiated from the resin molding is fluorescence having a wavelength range of 450 to 700 nm.

Hereinafter, embodiments of the present invention will be described in detail.
The resin molded body containing a fluorescent dye having photoelectric conversion ability used in the present invention absorbs electromagnetic waves in a low wavelength region including ultraviolet rays and emits electromagnetic waves in a long wavelength region, and γ rays having a wavelength of about 10 pm or less. It has a function of absorbing electromagnetic waves in an extremely low wavelength region. Hereinafter, the absorbed electromagnetic waves are collectively referred to as radiation.

Specifically, the resin molded body used in the present invention is used, for example, as a radiation absorbing sheet, a radiation absorbing net, or a radiation absorbing rigid plate.
The rigid plate-like body means a plastic plate containing a somewhat thick fluorescent dye.For example, a flat plate or corrugated plate produced by extrusion molding or liquid injection molding of a resin such as polycarbonate resin or acrylic resin is used. Can be mentioned.
The use of these resin moldings is not limited to the cultivation of agricultural crops because it has radiation absorption ability, but for various purposes that require radiation control, such as storage of radiation-containing substances, radioactive waste It can be used for storage.

When using a radiation-absorbing sheet and / or radiation-absorbing net for cultivation of agricultural products, it is used in a state of covering the agricultural products, but the covering mode is not particularly limited, and JP-A-2007-135583 and JP-A All the usage modes described in 2010-115193 as fluorescent radioactive agricultural materials for promoting photosynthesis can be applied.
In order to control the crops from radioactive contamination, for example, in the case of outdoor cultivation, the radiation absorbing net and / or the radiation absorbing net may be directly covered on the crops being cultivated. You may cover from the dome-shaped support body installed so that it may straddle.
In the case of a farmhouse for crop cultivation, at least a part of the outer wall member installed on the roof or wall of the house, the radiation absorbing sheet, the radiation absorbing net, and / or the radiation absorbing rigid plate It is composed of a solid body and controls crops grown inside from radioactive contamination.
Furthermore, when crops are in the shape of a ball like fruits, control the product from radioactive contamination by covering the growing fruits with a bag of the radiation-absorbing sheet or the radiation-absorbing net. Can do.

  As the fluorescent dye to be contained in the resin molding, nonionic fluorescent dyes, for example, polycyclic dyes such as violanthrone dyes, vilantron dyes, flavantron dyes, perylene dyes and pyrene dyes, xanthene dyes From among thioxanthene dyes, naphthalimide dyes, naphtholactam dyes, anthraquinone dyes, benzoanthrone dyes, coumarin dyes, and the like, those that can give the resin molded article radiation absorption ability may be selected. Further, in order to have a function of promoting photosynthesis, perylene dyes and naphthalimide dyes are preferable, and perylene dyes are particularly preferable.

  Examples of the perylene dye include Yellow 083, Orange 240, and Red 305 of trade names Lumogen F series manufactured by BASF Akchengezelshaft.

  Examples of naphthalimide dyes include Violet 570 and Blue 650 of the trade name Lumogen F series manufactured by BASF Akchengezelshaft.

  In order to exhibit the radiation absorption function and the photosynthetic promotion effect, particularly for agricultural crop cultivation, the resin molded body needs to be stable for a long period of time against wind and rain, changes in temperature, etc. It is desirable that the resin constituting the body and the fluorescent dye have good dispersibility and compatibility, and that the fluorescent dye does not leave the molded body.

As the resin constituting the resin molded body, a thermoplastic resin (a specific example will be described later), or a thermosetting resin such as an epoxy resin or a hybrid epoxy resin thereof can be used. Among these, it is preferable to use a thermoplastic resin from the viewpoint of compatibility with a fluorescent dye.
Examples of the thermoplastic resin include polyester, nylon, polycarbonate, polyacrylate, polymethacrylate, polyolefin, polyvinyl chloride, etc. From the above viewpoint, among the above thermoplastic resins, polyester, nylon, polyolefin resin Are preferably used, and polyester is particularly preferably used.
For the outer wall material of a general greenhouse, polyolefin resin, polyvinyl chloride, fluorine resin, etc. are used as the thermoplastic resin, but in the case of a resin molded body containing a fluorescent dye as in the present invention, As described above, it is necessary to select appropriately after considering the dispersibility and compatibility between the thermoplastic resin and the fluorescent dye.

  About polyester, it is desirable to use what synthesize | combined selecting the acid component and glycol component which comprise polyester suitably for the said objective.

  Examples of the polyester include acid components such as terephthalic acid, isophthalic acid, succinic acid, adipic acid, and 2,6-naphthalenedicarboxylic acid, ethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4- Examples thereof include a polymer obtained by condensation polymerization with a glycol component such as cyclohexanedimethanol and cyclohexanediol, and a copolymer obtained by replacing a part of the acid component and / or glycol component with a copolymerization component. Specifically, polyethylene terephthalate and polybutylene terephthalate are exemplified as preferable materials.

  Examples of nylon include nylon 6, nylon 6,6, nylon 6,10, nylon 11, nylon 12, nylon 6/11, nylon 6/12, and the like.

Furthermore, as the polyolefin, polyethylene resins such as high density polyethylene, medium density polyethylene, branched low density polyethylene, linear low density polyethylene, ethylene / α-olefin copolymer produced using a metallocene catalyst, Examples include polypropylene resins such as propylene homopolymer, ethylene-propylene block copolymer, and ethylene-propylene random copolymer.
The thermoplastic resin may be a biodegradable resin.

  The resin molded body may contain a fading preventing agent and / or a light resistance additive without departing from the spirit of the present invention. Further, commonly used additives such as an antioxidant, a dispersant, a lubricant, an antistatic agent, a pigment, an inorganic filler, a crosslinking agent, a foaming agent, and a nucleating agent can be blended.

It is preferable that the density | concentration of the said fluorescent pigment | dye contained in the said resin molding is 0.001-0.03 mass% with respect to the thermoplastic resin which comprises a resin molding, 0.015-0.02 mass % Is more preferable.
When the content of the fluorescent dye is insufficient, the radiation absorption function is deteriorated, and for photosynthesis, the amount of radiation (fluorescence) decreases as the amount of absorption of light such as sunlight decreases. Absent. Further, when the content of the fluorescent dye is excessive, the dispersibility and compatibility with the resin are deteriorated, and the fluorescent dye may be separated from the molded body, which is not preferable.

The radiation absorbing sheet and the radiation absorbing net are effective as crop growing materials for promoting photosynthesis. In JP 2007-135583 A and JP 2010-115193 A, a fluorescent radioactive sheet and a fluorescent radioactive net are used. It is as expressed as.
That is, when these fluorescent radioactive materials are used, natural light or artificial light and fluorescence are radiated to the crop in a well-balanced manner, and in particular, the fluorescence is radiated to the crop not only from one direction but from a plurality of directions as much as possible. It is expected as a new farming method because it has the advantages of activating photosynthesis, increasing the growth and weight of various crops such as vegetables, fruits and flowers, and increasing the sweetness of fruits.
The radiation-absorbing resin molded body has a function of converting harmful ultraviolet light into useful visible light, absorbs light in the wavelength range of 250 to 650 nm, and fluoresces in the wavelength range of 450 to 700 nm. In addition to the growth of various crops, it has an insecticidal effect. Further, in the case of a house using the radiation absorbing sheet and / or the radiation absorbing net having fluorescent emission as an outer wall material, the heat retaining property in the house is high, and the temperature in the house is compared with the outside in summer. Thus, the effect of lowering the temperature is brought about.

When using the radiation-absorbing sheet, the radiation-absorbing net and / or the radiation-absorbing rigid plate as a crop-growing material, there is no restriction on the installation location for the purpose of controlling the crop from radioactive contamination. For example, the inside of a lighted incubator (plant cultivation container) other than farmland, a greenhouse (including a house), a plant factory, etc. are mentioned.
Here, the greenhouse generally has the purpose of cultivating plants, and is a building whose outer frame is covered with glass, plastic, vinyl sheet, etc., but in the present invention, these glasses, A radiation-absorbing sheet, a radiation-absorbing net, and / or a radiation-absorbing rigid plate can be used in place of plastic and vinyl sheets as appropriate.

The crop cultivation method using the radiation absorbing material will be described.
A first embodiment of the present invention will be described.
The first embodiment is a method in which a light-reflective sheet as a light-reflective material is laid on a farmland where a crop is cultivated, and a radiation-absorbing sheet or a radiation-absorbing net is installed so as to cover the crop. .
The “agricultural land” in the present invention includes a farmland where crop seedlings are planted, a farmland where crop seeds are planted, a farmland where fruit trees are planted, etc. If it is cultivated, it shall correspond to farmland.

The radiation-absorbing sheet or the radiation-absorbing net converts a part of light constituting natural light or artificial light in the form of fluorescent light emission into light that can be used by plants for photosynthesis. Therefore, the light that has passed through the sheet or net has a favorable spectral balance for plant photosynthesis. The radiation-absorbing sheet and the radiation-absorbing net reflect light having a spectral balance that is favorable for plant photosynthesis in this way, and supplies light again to the crops.
Therefore, when combining a light-reflective sheet and a fluorescent radiation-absorbing sheet or radiation-absorbing net, use only the light-reflecting sheet on farmland without using the radiation-absorbing sheet or radiation-absorbing net. Compared with the case where the crop is covered with a radiation-absorbing sheet or a radiation-absorbing net without laying the light-reflective sheet on the farmland, the efficiency of photosynthesis can be significantly increased.

  Moreover, since the said light reflective sheet | seat is installed in the surface of farmland, it will be located under agricultural products. For this reason, the light reflective sheet can reflect the unused light that has not been irradiated to the crop as described above, and can irradiate the crop with the reflected light. For this reason, since the utilization rate of the light poured onto the crop can be improved, the photosynthesis of the crop is activated, resulting in an increase in the yield of the crop. Moreover, in the crop which bears fruit, the weight of a fruit can be increased and sugar content and nutrients can be increased.

Next, another example of the first embodiment of the present invention will be described.
In this example, a radiation-absorbing sheet or a radiation-absorbing net is laid on the farmland where the crop is cultivated, and a fluorescent radiation-absorbing sheet or a radiation-absorbing net is used as a material used to cover the crop. . This embodiment directly irradiates the crop with the fluorescence emitted by the fluorescent radiation-absorbing sheet or radiation-absorbing net upon receiving light and the light transmitted through the radiation-absorbing sheet or radiation-absorbing net covering the crop. In addition, the transmitted light irradiates the radiation absorbing sheet or the radiation absorbing net to irradiate the crop with the emitted fluorescence.

A specific example in which a radiation-absorbing net is used as a material covering crops and a radiation-absorbing sheet is used as a material laid on farmland will be described.
When the radiation absorbing net is irradiated with light, fluorescence is emitted from the net, and the crop is irradiated with the light that has passed through the gap of the net. Furthermore, when the fluorescence emitted from the net that does not irradiate crops and the sunlight that has passed through the gaps in the net reach the radiation-absorbing sheet, the radiation-absorbing sheet converts the wavelength of sunlight and emits new fluorescence. The fluorescence irradiates the crop.
Therefore, the crop receives the fluorescence from the two directions and the sunlight that has passed through the gap of the radiation absorbing net, and photosynthesis is activated. Furthermore, it is considered as a possibility that the fluorescence emitted from the radiation absorbing net and not irradiating the crop is reflected and irradiated to the crop after reaching the radiation absorbing sheet laid on the farmland.

  The radiation-absorbing sheet that can be used in the present invention will be described in detail later. However, since a thermoplastic resin containing a predetermined amount of a fluorescent dye is formed into a sheet shape, it is synthesized when irradiated with natural light or artificial light. It is possible to emit fluorescence having a wavelength range suitable for the above. For this reason, when a radiation-absorbing sheet is installed on the surface of the farmland, when the transmitted light that has passed through the gaps of the net located above the crop and has not been wavelength-converted reaches the surface of the farmland as unused light, Such unused light is absorbed by the radiation-absorbing sheet present on the surface of the farmland, and the absorbed unused light is again emitted upward as fluorescence and irradiated onto the crop. Therefore, the utilization rate of light poured onto the crop can be improved, so that the photosynthesis of the crop is activated and the yield of the crop is increased.

Next, still another example of the first embodiment of the present invention will be described.
In this example, a fluorescent radiation absorbing sheet is laid on a light reflecting sheet. In this case, as described above, it is possible to enjoy both the effective use of light by the light reflective sheet and the effective use of light by the radiation absorbing sheet. Further, a radiation absorbing net may be used instead of the radiation absorbing sheet.

As a method of installing a fluorescent radiation absorbing sheet or a radiation absorbing net so as to cover the crop, a method of directly hanging the sheet or net on the crop so as to cover the top of the crop, a dome installed so as to cover the crop Although the method etc. which make a type | mold support body support a sheet | seat or a net etc. are illustrated, it does not specifically limit. In order to support the sheet or net on the dome-shaped support, a plurality of arch-shaped supports that straddle the fence on which the crop is planted are set apart, and the support or cover is covered with the sheet or net. Embodiments are illustrated. In such an aspect, the entire bag is covered with a tunnel-like sheet or net. In this case, it is preferable that the longitudinal direction of the tunnel coincides with the north-south direction so that light is uniformly applied to the crops in the tunnel formed by the sheet or the net. For this purpose, it is preferable that the dome-shaped support is installed so that the longitudinal direction thereof coincides with the north-south direction.
Moreover, a radiation absorbing sheet or a radiation absorbing net may be used only by one sheet, and may be used by overlapping several sheets.

Next, a second embodiment of the crop cultivation method of the present invention will be described.
The second embodiment uses cylindrical or bag-shaped materials (collectively referred to as bag-shaped materials) made of a fluorescent radiation-absorbing sheet or a radiation-absorbing net, and the bag-shaped materials are being grown. Alternatively, it is a cultivation method in which the fruit or fruit receives fluorescence from the surroundings over the fruit, and furthermore, using an umbrella-shaped material made of a radiation-absorbing sheet, the fruit or fruit covered with the bag-shaped material It is a cultivation method performed by attaching the umbrella-shaped material above.
Fruits such as tomatoes, watermelons, cucumbers, and fruits such as apples, peaches, apricots, persimmons, pears, will improve fruiting when irradiated with red light. It is generally said that the contained nutrients and the like can be increased, and the cultivation method of the present invention is also effective for such purposes. In particular, by using such bag-like materials in the cultivation of red vegetables and fruits such as tomatoes, watermelons, and pink grapefruits, the antioxidant component lycopene contained in these vegetables and fruits is increased. Therefore, the added value of these vegetables and fruits can be increased.

Furthermore, the 3rd embodiment of the crop cultivation method of this invention is demonstrated.
A third embodiment is house cultivation using a fluorescent radioactive radiation absorbing net and / or a radiation absorbing sheet.
As a specific example, there is a method of using a house in which a radiation absorbing sheet and / or a radiation absorbing net is used as an outer wall material and installed on a roof portion or a wall surface.
Examples of the housing of the house in the present embodiment include a galvanized pipe and the like, but are not particularly limited. Moreover, it does not specifically limit about the structure of a house, a magnitude | size, a shape, etc., The thing currently used for the conventional greenhouse can be used.
As the outer wall material constituting the roof or wall surface of the house of the present invention, which of the radiation-absorbing sheet and the radiation-absorbing net is used can be appropriately selected according to the environment, the type of crops, and the like. it can.
For example, as a material for the roof portion, a sheet having no gap is suitable for avoiding rain and snow, but a net having a low porosity can also be selected. As an example of this, there is a case where a net is used in consideration of the air permeability in the house.
The farmland provided in such a house is irradiated with fluorescence emitted from fluorescent radiation-absorbing materials from multiple directions on the roof and walls, and also with sunlight in a well-balanced manner, so photosynthesis is active. The desired agricultural products can be cultivated.
In order to obtain the same effect as in the first embodiment, a light reflective sheet or a fluorescent radioactive material can be laid on the farmland surface in the house.

The other specific example regarding the cultivation using a house which is a 3rd embodiment is demonstrated.
This specific example is a cultivation method in which a conventional plastic greenhouse is used and a fluorescent radiation-absorbing material is installed so as to cover the crops or farmland cultivated therein.
This cultivation method is similar to the first embodiment, but since the sunlight entering the house is transmitted through the vinyl on the outer wall, the amount of light is lower than in other cases, and accordingly, the sunlight The amount of fluorescence radiated from the fluorescent radiation-absorbing material by light irradiation and reaching the crops and the amount of sunlight passing through the radiation-absorbing material and reaching the crops are also generally weakened.
Therefore, when selecting a radiation-absorbing sheet and a radiation-absorbing net, consider this point, and make the best use of the fluorescence emitted from the radiation-absorbing material to the maximum extent possible for crops. It is necessary to install a radiation-absorbing material so that the fluorescent light is irradiated from.
For example, the radiation-absorbing material is angled so that a large-area radiation-absorbing material is folded and installed on a farm product, or multiple radiation-absorbing materials are installed on a farm product. It is preferable to install.

  Next, the fluorescent radiation radiation absorbing sheet and radiation absorbing net used in the present invention will be described. The radiation-absorbing sheet and radiation-absorbing net used in the present invention have a function of absorbing harmful ultraviolet rays and light in the blue light region and converting them into useful visible rays when irradiated with light such as sunlight. What is needed, that is, what emits light in a band particularly used for the photosynthetic reaction of plants as fluorescence, for this purpose, absorbs light in the wavelength range of 250 to 650 nm and has a wavelength range of 450 to 700 nm. Those that emit fluorescence are preferred.

Moreover, the present inventors measured the temperature in a house using (1) the conventional vinyl house, and (2) the house which comprises all the roof parts and wall surfaces with the radiation absorbing sheet used for this invention. However, when the outside air temperature is about 30 ° C. and the solar radiation intensity is about 800 W / m ² , the temperature is about 35 ° C. in the case of (1), while it is about 27 ° C. in the case of (2). Met.
This is probably because the radiation absorbing sheet used in the present invention attenuates light in the short wavelength region, so that the energy taken into the house is greatly reduced, and the energy of about 30 to 40% is reduced. Inferred.

Furthermore, when irradiated with light, the fluorescent radioactive radiation-absorbing material used in the present invention emits not only 450-700 nm fluorescence effective for photosynthesis from the surface, but actually far-infrared rays having a longer wavelength. From this, it is considered that the radiation absorbing material used in the present invention has a high reflectance of the inner surface with respect to far infrared rays, and conversely, the emissivity for radiating far infrared rays to the outside is small. Therefore, especially in the case of a house composed of a radiation-absorbing sheet, it is presumed that this property has a higher heat retention than a conventional vinyl house.
Furthermore, the radiation-absorbing sheet and radiation-absorbing net used in the present invention also have an insect repellent (insect control) effect.

The fluorescent radioactive radiation-absorbing material used in the present invention has a fine uneven state on the surface, not optically smooth, in order to efficiently emit the fluorescence generated inside the material constituting them to the outside. A rough surface is preferably formed. Since the surface is such a rough surface, the fluorescence generated inside the material is irregularly reflected on the rough surface, and the amount of fluorescent light emitted to the outside of the material increases due to the irregular reflection. The effect can be further enhanced.
As will be described later, the radiation-absorbing material used in the present invention is a thin or thin material, so that fine irregularities are present on the surface from the beginning, but in order to extract fluorescence more efficiently to the outside. Moreover, you may provide an unevenness | corrugation in the surface of the raw material which comprises these intentionally.

  The fluorescent radiation-absorbing material used in the present invention absorbs natural light and artificial light, and radiates wavelength-converted fluorescence from the upper surface (front surface) and the lower surface (back surface) to bring about an effect of promoting photosynthesis. is there. Here, when a woven or knitted fabric such as a fluorescent radiation-absorbing net is used, the woven or knitted fabric is knitted with a gap (referred to as a gap) between the weft and the warp. Not all are converted to fluorescence. For this reason, light necessary for photosynthesis is allowed to pass from the gap, and the gap contributes to the growth of crops, such as ensuring air permeability and releasing excessive moisture.

The porosity of the fluorescent radiation absorbing net in the present invention will be described.
The porosity means the ratio of the area of the void portion to the total area of the net.
It is preferable to reduce the porosity, that is, to increase the amount of net material by narrowing the mesh of the net, since this reduces the amount of radiation passing through and increases the amount of emitted fluorescence. Adjustment is preferable because the amount of transmitted natural light or artificial light is reduced.

  A plurality of fluorescent radiation-absorbing materials used in the present invention can be used as needed. In the case of the net, the porosity of the net can be adjusted, so that the balance between the light transmitted through the net and the wavelength-converted fluorescence can be adjusted according to the crop.

  The radiation-absorbing net used in the present invention is produced from a composition comprising at least a thermoplastic resin and a fluorescent dye as a raw material. For example, a film obtained by molding such a composition is cut and Examples thereof include woven and knitted fabrics made from a flat yarn, monofilament, composite monofilament and the like obtained by processing. Although it does not specifically limit as such a woven / knitted fabric, A net | network (net | network) can be illustrated.

  Among the above-mentioned materials for producing the radiation-absorbing net used in the present invention, the flat yarn has a thickness of preferably about 5 to 150 μm, and more preferably about 10 to 100 μm. Moreover, about a monofilament, it is preferable that a fiber diameter is 140-1000 micrometers, and it is more preferable that it is about 220-700 micrometers. In addition, it is preferable that the thickness of the film used as a raw material of a flat yarn is about 0.2-0.7 mm, and it is more preferable that it is about 0.1-0.5 mm.

On the other hand, the film constituting the radiation-absorbing sheet and the radiation-absorbing net used in the present invention can be obtained by molding, for example, using a composition composed of at least a thermoplastic resin and a fluorescent dye as a raw material. The same applies to the absorbent rigid plate-like body.
Although it does not specifically limit as a shaping | molding method, Extrusion molding, injection molding, compression molding, etc. can be used, Especially extrusion molding is used preferably. The thickness of the sheet is exemplified by about 0.2 to 0.7 mm, but is not limited thereto, and may be appropriately determined in consideration of factors such as required strength and cost.

  The fluorescent dye used in the radiation-absorbing net, radiation-absorbing sheet, and radiation-absorbing rigid plate used in the present invention absorbs radiation when such materials are irradiated with light such as sunlight. However, the emitted light (fluorescence) generated needs to exhibit a photosynthetic promoting effect, and is not particularly limited as long as these conditions are satisfied.

  Therefore, when any of yellow, orange, and red light is desired as the emitted light, the light absorption wavelength region is preferably 400 to 600 nm, more preferably 470 to 600 nm, and sunlight or the like. A fluorescent dye having a wavelength region of the emitted light generated when irradiated with light in a range of 450 to 700 nm is preferably used for obtaining a photosynthesis promoting effect. In addition, by using such a fluorescent dye, the various effects described above can be obtained.

  In addition, when a red color is desired as the emitted light, the light absorption wavelength region is preferably 250 to 650 nm, and the wavelength region of the emitted light generated when irradiated with light such as sunlight is 450 to 650. Fluorescent dyes such as those present at 700 nm are preferably used.

  In addition, it is preferable to make the radiation absorbing sheet or radiation absorbing net used in the present invention contain one kind of fluorescent dye. When a plurality of fluorescent dyes are contained, it is not preferable because the absorbed light tends to be divided to reduce the amount of fluorescence. Therefore, when it is necessary to contain a plurality of fluorescent dyes, a plurality of radiation-absorbing sheets or radiation-absorbing nets may be used, and different kinds of fluorescent dyes may be contained in each.

  The present inventors have repeatedly used the above-mentioned fluorescent radiation-absorbing sheet or radiation-absorbing net, so that the fluorescent dye gradually elutes from these, and the radiation (fluorescence) intensity decreases, and the expected result is achieved within a short period of time. The phenomenon that the effect of disappears was confirmed. The reason why such a phenomenon occurs is presumed that the compatibility between the thermoplastic resin and the fluorescent dye or the dispersibility of the fluorescent dye is insufficient, so that the combination of the thermoplastic resin and the fluorescent dye has good compatibility. It is preferable to select one.

  Next, among the radiation-absorbing materials used in the present invention, a fluorescent radiation-absorbing woven or knitted fabric, particularly a radiation-absorbing net will be described in detail.

  The raw yarn used to manufacture the radiation-absorbing net is a flat yarn obtained by slitting a film produced by various molding machines and then drawing, a split yarn obtained by splitting a flat yarn, a circular or irregular nozzle A monofilament such as a monofilament obtained by stretching a filament extruded from or a multifilament obtained by focusing a low-definition filament, a composite yarn such as a multi-layer, a core-sheath, or a parallel-type can be used without limitation.

  In addition, in order to produce a fluorescent radioactive net, a twisted yarn having a diameter of about 0.3 to 0.5 mm is made from a long film obtained by slitting the film, and 3 to 5 pieces of the twisted yarn are bundled. It can also be used as a material.

  A film used for producing a flat yarn is a mixture obtained by mixing a thermoplastic resin with a predetermined ratio of a fluorescent dye in advance using a mixer such as a Henschel mixer, and feeding the mixture to an extruder, or kneading, or It can be prepared by using a known method such as an extrusion molding method, an injection molding method, a compression molding method, etc. after supplying a predetermined proportion of thermoplastic resin and fluorescent dye directly to an extruder and kneading them. . In addition, a masterbatch in which a high-concentration fluorescent dye is previously contained in the same or similar resin as the base thermoplastic resin is prepared, and the film is adjusted so that the fluorescent dye has a predetermined content at the time of film formation. You may employ | adopt what is called a masterbatch method which shape | molds.

  For example, when using a film obtained by an extrusion molding method, a flat yarn is a mixture of the above thermoplastic resin such as polyolefin, polyester or nylon and a fluorescent dye, and is charged into an extruder. Then, it is extruded in an amorphous state by the T-die method or the inflation method and then cooled and solidified. The resulting film is slit to a width of about 2 to 50 mm, preferably about 5 to 30 mm, and then stretched and then heat-treated. Is done. The stretching treatment at this time is performed at a temperature below the melting point of the high melting point thermoplastic resin or above the softening point of the low melting point thermoplastic resin. The heating method includes a hot roll type, a hot plate type, a hot air type, etc. Any method may be adopted.

  The slit thermoplastic film is heated and drawn by a roll having a circumferential speed difference between the front and rear rolls, thereby forming a drawn yarn. The draw ratio is preferably 3 to 15 times, more preferably 4 to 12 times, and most preferably 5 to 10 times. If the draw ratio is 3 times or more, sufficient strength of the flat yarn can be obtained. Moreover, if the draw ratio is 15 times or less, it is possible to prevent the flat yarn from being cracked due to the orientation in the drawing direction being too strong. Further, the single yarn fineness of the drawn yarn is usually 200 to 10000 dtex (hereinafter abbreviated as dt), preferably 500 to 5000 dt.

  In producing the woven or knitted fabric, at least two kinds of materials for warp and weft are used. Such materials are selected from, for example, long films, flat yarns, monofilaments, and the like and secondary processed products thereof, but the two types of materials may be the same or different. It may be. Therefore, the woven or knitted fabric used in the present invention includes those woven using different materials for the warp and the weft.

Moreover, the two types of materials used for the warp and the weft may contain fluorescent dyes having the same emission wavelength range, or may contain fluorescent dyes having different emission wavelength ranges. Examples of fluorescent dyes having different emission wavelength ranges include the same type of fluorescent dyes having the same dye skeleton but different substituents, and different types of fluorescent dyes having different dye skeletons.
However, at least one of the different fluorescent dyes needs to be radiation absorbing.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited to the following Example.

<Production of radiation absorbing net A>
(1) Production of a film as a material for a radiation-absorbing net As a thermoplastic resin, ethylene glycol / 1,4-cyclohexanedimethanol = 60/40 (mass ratio) as a glycol component and terephthalic acid as an acid component are condensed. A polyester resin (manufactured by SK Chemicals, trade name: PET-G, brand: S2008) obtained by polymerization was prepared. This polyester resin is blended with 0.02% by mass of a perylene dye (manufactured by BASF Akchengezelshaft Co., Ltd., trade name: Lumogen F Red305) as a fluorescent dye, and kneaded with a Henschel mixer. Was made. Next, using a 65 mmφ extruder, the resin composition obtained by the T-die method (melting temperature 260 ° C.) was formed into a film shape and cooled and solidified at 30 ° C. to prepare a film having a thickness of 60 μm. The perylene fluorescent dye used absorbs light in the wavelength region of about 520 to about 590 nm (maximum absorption wavelength is 578 nm) and emits fluorescence in the wavelength region of about 600 to about 680 nm (maximum fluorescence wavelength). 613 nm).

(2) Production of radiation-absorbing net A A twisted yarn having a diameter of about 0.4 mm was produced from the long film obtained by slitting the film of (1) above, and a bundle of three twisted yarns. The material was used for net production. Next, using this material as warp and weft, a radiation-absorbing net A having a mesh size of 1.5 cm × 1.5 cm (porosity of about 83%) was produced by a Russell knitting machine.

<Production of radiation absorbing net B>
From the film produced in the same manner as (1) above, a radiation-absorbing net B (porosity of about 40%) having a mesh size of 0.5 cm × 0.5 cm was produced in the same manner as (2) above.

<Production of radiation absorbing net C>
From the film produced in the same manner as in the above (1) except that a perylene-based dye (manufactured by BSF Akchengezelshaft, trade name: Lumogen F Red300) is used as the fluorescent dye, a mesh is formed in the same manner as in the above (2). A 0.5 cm × 0.5 cm radiation-absorbing net C (porosity of about 40%) was produced.

<Production of radiation absorbing sheet>
Byron SI-173 manufactured by Toyobo Co., Ltd. is used as the polyester resin, and perylene dyes used for the production of the radiation absorbing net A and the radiation absorbing net B are used as the fluorescent dyes (trade name: manufactured by BSF Aktiengesellschaft) After adding 0.02 mass% of Lumogen F Red305), it was formed into a film by an inflation molding method to produce a radiation absorbing sheet. The light transmittance of this radiation absorbing sheet was about 85%.

<Example 1>
(House cultivation test of spinach using radiation absorbing sheet)
A dome-shaped pipe house installed in farmland in the Izumino area of Chino City, Nagano Prefecture, about 5.4m in the east-west direction, about 30m in the north-south direction, and about 3.0m in height is covered with a radiation-absorbing sheet. A vinyl sheet (MKV Plastics Co., Ltd., trade name: Agristar) was covered. After that, make a bag about 30m in the north-south direction, about 130cm in the east-west direction and about 15cm in height, and then cover a normal vinyl sheet (made by MKV Plastics Co., Ltd., trade name: Agristar) on it for the purpose of keeping warm. Next, spinach was sown on December 1, 2010, and a cultivation test was started in March with the planned harvest. In addition, the seed of spinach was “Spider” manufactured by Tokita Seedling Co., Ltd.

<Example 2>
(Cultivation test of spinach using radiation absorbing net A)
Near the entrance of the house installed in Example 1, a cocoon having a length of about 130 cm in the north-south direction, about 30 m in the east-west direction and a height of about 15 cm was formed, and spinach was sown on December 1, 2010. Immediately thereafter, a plurality of tunnel struts were fixed in the north-south direction with a height of about 40 cm from the surface of the ridge and a length between fixed portions of about 150 cm, with both ends straddling the ridge. Next, the radiation absorbing net A having a width of about 1.6 m was covered from the top of the support column, and the spinach cultivation test was started with a plan to harvest in March. In addition, the seed of spinach was “Spider” manufactured by Tokita Seedling Co., Ltd.

<Radioactivity measurement of spinach>
The spinach cultivated in Example 1 and Example 2 was randomly extracted on March 25, 2011, and 200 g each of the edible portion was used as an analysis sample. The Japan Analysis Center (Inage-ku, Chiba City, Chiba Prefecture) (Sanno-machi) was requested to measure radioactivity.
The contents of the “Analysis Result Report” showing the measurement results are described below.

注）１．分析結果は、計数値がその計数誤差の３倍を超えるものについては有効数字２桁で表し、それ以下のものについては※※で示した。
２．誤差は計数誤差のみを示した。
３．測定結果については、減衰補正を行っていない結果である。
６所見：
原子力安全委員会により示された「飲食物摂取制限に関する指標」未満であった。 <Analysis result report>
1. Contract title: Radioactivity measurement of environmental samples Analysis item: Quantification of cesium 134, cesium 137 and iodine 131 by γ-ray spectrometry Analysis method: An analysis sample was packed in a U-8 container to obtain a measurement sample.
4). Measurement Method (1) Measurement Using a germanium semiconductor detector, the measurement sample was measured for 1800 seconds, and the radiation concentration was calculated. In principle, the data were in accordance with Atomic Data and Nuclear Data Tables (1983).
(2) Measuring equipment Germanium semiconductor detector (manufactured by ORTEC, GEM-50195S, etc.)
5. The analysis results are shown in Table 1.

Note) The analysis results are indicated by two significant figures if the count value exceeds three times the count error, and indicated by ** if it is less than that.
2. The error showed only counting error.
3. The measurement result is a result of no attenuation correction.
6 findings:
The value was less than the “indicator on food and beverage intake restriction” provided by the Nuclear Safety Commission.

From Table 1, the becquerel value representing the radiation dose of the detected iodine 131 is 13 ± 3.7 becquerel when the radiation absorbing sheet of Example 1 is used, and the radiation absorbing net of Example 2 is used. In the case, it is 17 ± 4.6 becquerels, and it can be seen that the latter is higher by about 4 becquerels.
This is because the radiation-absorbing net A has a 1.5 cm × 1.5 cm mesh (porosity of about 83%) and the radiation passes through the mesh, so that it is more than the case of a radiation-absorbing sheet without a mesh. It is estimated that the becquerel value of spinach increases. In other words, this difference in the becquerel value indicates that the radiation-absorbing sheet absorbs a larger amount of radiation than the radiation-absorbing net, and that the resin molded body is radiation-absorbing, as long as there is no mesh through which radiation passes. It has been demonstrated.

  In addition, Table 2 shows the results of radiological inspections conducted by Nagano Prefecture on spinach collected in various areas of Nagano Prefecture on April 6, which was published in the Nagano Daily (newspaper) dated April 9, 2011.

“Indices on food and beverage intake restriction” provided by the Nuclear Safety Commission are as follows: (1) For radioactive iodine (131), 2000 Bq / Kg for vegetables (excluding root vegetables and moss), (2) Radiocesium Is about 500 Bq / Kg for vegetables.
Therefore, the measurement results of the present invention shown in Table 1 and the measurement results of Nagano Prefecture shown in Table 2 are both becquerel values below the above index and do not affect the human body.

However, comparing the measurement results of both, (1) About radioactive iodine (131), the value of Nagano Prefecture is 2 to 7 times higher than that of the present invention, and (2) About radioactive cesium In the case of the present invention, it is hardly detected, whereas in the case of Nagano Prefecture, it is detected at any of the three locations, and especially the 370 vector of Nagano city is a high value close to the index.
In the case of the present invention, this clearly shows the effect of using the radiation absorbing material, but in the case of Nagano Prefecture, it is probably the result of the conventional cultivation method that does not use such material.

Claims (13)

  A radioactive contamination control method using a resin molded article that contains a fluorescent dye having light conversion performance and absorbs electromagnetic waves in a low wavelength region including radiation and emits electromagnetic waves in a long wavelength region.   The radioactivity according to claim 1, wherein the resin molded body is a sheet-like body or a net-like body, and the agricultural product being grown is covered with the sheet-like body and / or the net-like body to control the agricultural product from radioactive contamination. Pollution control method.   The resin molded body is a sheet-like body or a net-like body, and at least a part of the roof part and the wall part is cultivated in a house composed of the sheet-like body and / or the net-like body, The radioactive contamination control method of Claim 1 which controls from radioactive contamination.   2. The resin molded body is a rigid plate-like body, and a crop is cultivated in a house in which at least a part of the roof portion and the wall portion is composed of the rigid plate-like body, and the crop is controlled from radioactive contamination. The radioactive contamination control method described in 1.   The method for controlling radioactive contamination according to any one of claims 1 to 4, wherein the electromagnetic wave radiated from the resin molding is 450 to 700 nm fluorescence effective for promoting photosynthesis.   6. The radioactive contamination control method according to any one of claims 1 to 5, wherein the fluorescent dye is a perylene dye.   A radiation-absorbing material comprising a resin molded article that contains a fluorescent dye having light conversion performance and absorbs electromagnetic waves in a low wavelength region including radiation and emits electromagnetic waves in a long wavelength region.   The radiation absorbing material according to claim 7, wherein the fluorescent dye is a perylene dye.   The radiation-absorbing material according to claim 7 or 8, wherein the fluorescent dye absorbs electromagnetic waves in a low wavelength region including radiation and emits fluorescence in a wavelength region of 450 to 700 nm.   The radiation-absorbing material according to claim 7, wherein the resin molded body is a sheet-like body or a net-like body.   The radiation-absorbing material according to claim 7, wherein the resin molded body is a rigid plate-like body.   A crop-growing material comprising the radiation-absorbing material according to any one of claims 7 to 11.   A crop-growing material comprising a house in which at least a part of a roof portion and / or a wall portion is composed of the radiation-absorbing material according to any one of claims 7 to 11.