JP5685283B2 - Radionuclide capture net and aqueous coating agent composition - Google Patents

Description

  The present invention relates to a radionuclide trapping net and an aqueous coating agent composition, and more particularly, a radioactivity useful for protecting agricultural products from contamination by radionuclides such as radiocesium and decontamination of various pollutants by radionuclides. The present invention relates to an aqueous coating agent composition capable of forming a radionuclide trapping layer on the surface of a nuclide trapping net and film or fabric.

  Cesium separation and recovery technology is the separation, recovery, and contamination of radioactive cesium from waste liquids containing nitric acid and sodium nitrate as the main components generated from facilities related to nuclear power, such as spent fuel reprocessing facilities. This is an extremely important technology that can be applied to the removal of radioactive cesium from drinks such as milk and the recovery of cesium contained in waste geothermal water.

Currently, the recovery and removal of radioactive cesium is being investigated in various ways in many departments in the nuclear field.
Radioactive cesium is produced by fission reactions such as uranium 235, and cesium 137 (half-life: 30.04 years), cesium 134 (half-life: 2.06 years), etc. are known, but in particular, cesium 137 is halved. There is a need for an effective removal method that is long in term and easy to elute because it is an alkali metal and contained in various waste liquids of nuclear facilities.

  As a method for removing radioactive cesium, for example, (1) an evaporative separation method, (2) an ion exchange adsorption method using an ion exchange resin or zeolite as an ion exchanger, (3) a coprecipitation method using a ferrocyanide compound, (4) Zeolite adsorption method supporting metal ferrocyanide is known, but evaporation separation method requires evaporation of the whole liquid. At that time, leakage of cesium due to entrainment of droplets, coexistence in ion exchange method The salt interference and coprecipitation methods have various problems such as poor operability because the metal ferrocyanide compound is gelatinous.

  As a cesium separating material, conventionally, a hexacyanoferrate (II) copper supported in porous resin pores (see, for example, Patent Document 1), or an ammonium phosphomolybdate in pores of a porous inorganic support. (Patent Document 2) is known, but such a cesium separation material is effective in a system in which a column is filled and an aqueous solution containing cesium is passed through to adsorb and remove the cesium. However, it is difficult to use the cesium separating material supported on a fabric such as a nonwoven fabric or a woven fabric.

On the other hand, in recent years, it has been found that Prussian blue (bituminous blue) has a cesium capturing ability, and it has been confirmed that cotton cloth and nonwoven fabric dyed with Prussian blue can effectively capture cesium. And since this Prussian blue is utilized for various uses, the research of the nanoparticulation is advanced, and the patent document 3 describes the production method of Prussian blue type metal complex nanoparticles, and the Prussian blue type obtained thereby. Metal complex nanoparticles and dispersions thereof are disclosed.
However, when producing a cotton fabric or nonwoven fabric dyed with such a dispersion of Prussian blue-type metal complex nanoparticles, a new dyeing process is required. The problem that it is not possible arises.

Japanese Patent Laid-Open No. 9-173832 JP 2000-84418 A WO2008 / 081923 pamphlet

  The present invention has been made under such circumstances, and is useful for protecting agricultural products from contamination by radionuclides such as radiocesium and radiostrontium, and for decontamination of various pollutants by radionuclides. It is an object of the present invention to provide an aqueous coating agent composition capable of forming a radionuclide trapping layer on the surface of a film or fabric while providing the trapping net with a simple operation without requiring a dyeing process. .

  The inventors of the present invention have previously divided a split-layer structure in which a split fiber web (A) and (B) made of polyvinyl alcohol are vertically and horizontally orthogonally stacked via a polyvinyl alcohol adhesive layer. A fiber nonwoven fabric was developed (Japanese Patent Laid-Open No. 2010-138524).

As a result of intensive studies to achieve the above object, the present inventors have focused on the above-mentioned split fiber nonwoven fabric and obtained the following knowledge.
The adhesive constituting the polyvinyl alcohol-based adhesive layer in the split fiber nonwoven fabric contains polyvinyl alcohol as an adhesive resin component at a certain value or more, and contains ammonium phosphomolybdate as a radionuclide trapping material. The desired radionuclide capture net can be obtained, and the above-mentioned polyvinyl alcohol-based adhesive contains ammonium phosphomolybdate as a radionuclide capture material, thereby forming a radionuclide capture layer on the surface of the film or fabric. It has been found that an aqueous coating agent composition that can be obtained is obtained.
The present invention has been completed based on such findings.

That is, the present invention
[1] A split fiber nonwoven fabric having a two-layer structure in which split fiber webs (A) and (B) made of polyvinyl alcohol are laminated vertically and horizontally through a polyvinyl alcohol adhesive layer. , the adhesive constituting the adhesive layer is adhered with containing at least 50 wt% polyvinyl alcohol as the resin component, Ri polyvinyl alcohol-based adhesive der containing phosphomolybdic acid ammonium as radionuclide capturing material, the polyvinyl alcohol the content of phosphorus ammonium molybdate in the adhesive, wherein the 0.1~25g / m ² der Rukoto respect to the nonwoven fabric, radionuclide capture net,
[2] The split fiber web (C) made of ethylene-vinyl alcohol copolymer and the split fiber web made of polyvinyl alcohol or the split fiber web (D) made of ethylene-vinyl alcohol copolymer form the adhesive layer. A split fiber nonwoven fabric having a two-layer laminated structure, which is vertically and horizontally laminated, wherein the adhesive constituting the adhesive layer contains 50% by mass or more of polyvinyl alcohol as an adhesive resin component, and is radioactive nuclide capturing material polyvinyl alcohol-based adhesive der containing phosphomolybdic acid ammonium Ri as the content of phosphoric ammonium molybdate in the polyvinyl alcohol-based adhesive, in 0.1~25g / m ² with respect to the non-woven fabric and wherein the Rukoto Oh, radioactive nuclides capture net,
[ 3 ] The radionuclide trapping net according to the above [1] or [2 ], wherein the radionuclide is at least one of radiocesium, radiostrontium, radiocobalt, and radiomanganese.
[ 4 ] The radionuclide trapping net according to any one of [1] to [ 3 ] above, wherein the polyvinyl alcohol-based adhesive is an aqueous adhesive,
[ 5 ] The radionuclide according to any one of [1] to [ 4 ] above, wherein the polyvinyl alcohol-based adhesive contains a polyvinyl acetate-based or polyurethane-based adhesive resin component in a proportion of 50% by mass or less. Capture net ,
A, it is intended to provide.

According to the present invention, a radionuclide capture net useful for protection of agricultural products from contamination by radionuclides such as radioactive cesium and radiostrontium and decontamination of various pollutants by radionuclides is provided by a simple operation. An aqueous coating agent composition capable of forming a radionuclide capturing layer on the surface of a film or fabric can be provided.
Further, according to the present invention, it is possible to efficiently capture the radionuclide regardless of its concentration.
Furthermore, according to the radionuclide trapping net of the present invention, when processing waste, it is lightweight, and the volume can be reduced by reducing the volume.

In Table 4, [E] = log [C] is the horizontal axis and [F] = log [D] is the vertical axis, and log [C] and log [D] are in a proportional relationship. It is a graph which shows that there exists.

  The radionuclide trapping net of the present invention comprises a polyvinyl alcohol-based split fiber nonwoven fabric. In the present invention, there are two modes of split fiber nonwoven fabrics I and II as the split fiber nonwoven fabric.

[Split fiber nonwoven fabric I]
In the split fiber nonwoven fabric I constituting the radionuclide trapping net of the present invention, the split fiber webs (A) and (B) made of polyvinyl alcohol are laminated vertically and horizontally through a polyvinyl alcohol adhesive layer. A split alcohol nonwoven fabric having a two-layer structure, wherein the adhesive constituting the adhesive layer contains 50% by mass or more of polyvinyl alcohol as an adhesive resin component and also contains a radionuclide capturing material. It is characterized by being.

(Split fiber web (A) and (B))
In the split fiber nonwoven fabric I, the split fiber web used as the (A) and (B) layers is a web made of polyvinyl alcohol (hereinafter sometimes abbreviated as “PVA”).
The PVA is obtained by substantially completely saponifying polyvinyl acetate, and usually contains a small amount of glycerin as a plasticizer in order to improve film forming properties.
The PVA split fiber webs (A) and (B) can be produced, for example, as follows.
First, a PVA film containing glycerin as a plasticizer is formed by a conventionally known method, and then uniaxially stretched so as to be about 4 times or more in the longitudinal direction, and then the stretched film is split (split). It is made into a net shape and the dimensions are fixed by high temperature heat treatment.
Although there is no restriction | limiting in particular in the said uniaxial stretching process method, It is good to perform uniaxial stretching by the speed difference between rolls in the suitable temperature more than the glass transition temperature of PVA containing glycerin as a plasticizer and less than melting temperature. Thereby, the molecular orientation is aligned in the stretching direction, and the next split processing is facilitated. For split processing, various known splitters can be used as appropriate.
In addition, when forming a PVA film, an ultraviolet absorber, a hindered amine light stabilizer, an antioxidant, and the like can be added as appropriate in order to make the weather resistance better together with the plasticizer glycerin.

(Preparation of split fiber nonwoven fabric I)
The split fiber nonwoven fabric I can be produced by vertically laminating the PVA split fibers (A) and (B) obtained as described above vertically and laterally through an adhesive layer. . In addition, the said length refers to a elongate direction and a width refers to the width direction.
In the present invention, the thicknesses of the split fiber webs (A) and (B) are preferably independently in the range of 10 to 70 μm.
The raw fabric of the split fiber nonwoven fabric I having a two-layer laminated structure according to the present invention thus produced usually has a length of about 80 to 120 m and a width of about 1 to 3 m. Furthermore, when it is spread on an actual site, a wide width may be required, and at that time, a width of 30 m is possible by width-ordering.

<Adhesive layer>
The split fiber nonwoven fabric I has a two-layer laminated structure in which the above-described split fiber web (A) and the split fiber web (B) are vertically laminated horizontally and vertically via an adhesive layer. As an adhesive constituting the adhesive layer, it is necessary to use a PVA adhesive containing 50% by mass or more of PVA as an adhesive resin component and containing a radionuclide capturing material.
Thus, by using a PVA adhesive containing 50% by mass or more of PVA as the adhesive resin component, the obtained split fiber nonwoven fabric has improved hygroscopicity. As this PVA adhesive, a water-based adhesive is usually used.
In addition, when a stronger adhesive strength is required, a PVA adhesive comprising a polyvinyl acetate (modified PVA) or polyurethane as an adhesive resin component in a proportion of 50% by mass or less, preferably 30% by mass or less. An agent can be used. When a polyvinyl acetate (modified PVA) adhesive or a polyurethane adhesive is blended with a PVA adhesive to prepare a polyvinyl acetate (modified PVA) or a PVA adhesive containing polyurethane, the polyvinyl acetate As the system (modified PVA system) adhesive and the polyurethane adhesive, an aqueous adhesive is usually preferable.
The coating amount of the adhesive for the adhesive layer is usually about 0.5 to 10 g / m ² , preferably 1.0 to 8 g / m ² .

≪Radionuclide capture material≫
In the present invention, the PVA adhesive contains ammonium phosphomolybdate as a radionuclide capturing material.
It is preferable that ammonium phosphomolybdate is contained in an amount of 0.1 to 25 g / m ² with respect to the nonwoven fabric when the radionuclide trapping net is used. Although there is no restriction | limiting in particular in content of ammonium molybdate, Generally it is suitable to contain in the PVA-type adhesive agent in the quantity of 0.2-50 mass%.
Ammonium phosphomolybdate is a compound having a chemical structure of (NH ₄ ) ₃ PMo ₁₂ O ₄₀ and is particularly excellent in cesium trapping performance.
In the present invention, it is an important feature that ammonium phosphomolybdate is used as a radionuclide capturing material. In addition to ammonium phosphomolybdate, other radionuclide capturing materials such as Prussian blue (bituminous) particles, hexacyanoiron (II ) Using at least one radionuclide scavenger selected from acid copper-supported porous carrier particles, mica particles, zeolite particles, borosilicate zeolite particles, kaolin particles, bentonite particles, microalgae, and ion exchange resins It does not exclude use.
The particle size of these radionuclide trapping materials is preferably as small as possible from the viewpoint of dispersibility in the PVA adhesive and surface area.
Examples of the radionuclide include radioactive cesium such as cesium 137 and cesium 134, manganese 54, cobalt 60, radioactive strontium, iodine 131, and the like.

In the radionuclide trapping net of the present invention, the following effects can be obtained by adding ammonium phosphomolybdate to the PVA adhesive.
Cesium is an alkali metal and is soluble in water, and PVA is also hydrophilic and hygroscopic. On the other hand, since ammonium phosphomolybdate is difficult to dissolve in water, ammonium phosphomolybdate is dispersed in the PVA adhesive using water as a medium. As a result, ammonium phosphomolybdate in the PVA adhesive is , Cesium can be efficiently captured in a short time.
Furthermore, the split fiber nonwoven fabric is a film-like net base material, has a large area in contact with the radionuclide, and is advantageous for capturing the radionuclide. In addition, since the PVA adhesive covers the surface of the net base material, water easily penetrates into the ammonium phosphomolybdate present therein if there is rain, etc., and cesium contacts the ammonium phosphomolybdate. Is advantageous.

Next, the split fiber nonwoven fabric II will be described.
[Split fiber nonwoven fabric II]
The split fiber nonwoven fabric II constituting the radionuclide trapping net of the present invention is composed of a split fiber web (C) made of an ethylene-vinyl alcohol copolymer and a split fiber web made of polyvinyl alcohol or an ethylene-vinyl alcohol copolymer. The split fiber web (D) is a split fiber nonwoven fabric having a two-layer laminated structure in which the longitudinal and horizontal cross layers are laminated with an adhesive layer interposed therebetween, and the adhesive constituting the adhesive layer is an adhesive resin component It is characterized by being a PVA adhesive containing 50% by mass or more of polyvinyl alcohol and containing a radionuclide trapping material.

(Split fiber web (C))
In the split fiber nonwoven fabric II, the split fiber web used as the (C) layer is made from an ethylene-vinyl alcohol copolymer.
The ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as “EVOH”) is obtained by substantially completely saponifying an ethylene-vinyl acetate copolymer, and comprises ethylene units. The content is preferably in the range of 10 to 50 mol%. If the ethylene unit content is less than 10 mol%, the hygroscopicity is good, but the handling properties are poor. On the other hand, if it exceeds 50 mol%, the handling properties are good, but the hygroscopicity is lowered. From the viewpoint of the balance between handling properties and hygroscopicity, the ethylene unit content is more preferably 16 to 44 mol%, further preferably 21 to 44 mol%, particularly preferably 21 to 34 mol%.
The EVOH split fiber web can be produced, for example, as follows.

First, EVOH is formed by a conventionally known method, then uniaxially stretched so as to be about 4 times or more in the longitudinal direction, and then this stretched film is made into a net by splitting (split) processing and is subjected to high-temperature heat treatment. To fix the dimensions.
Although there is no restriction | limiting in particular in the said uniaxial stretching process method, It is good to perform uniaxial stretching by the speed difference between rolls in the suitable temperature more than the glass transition temperature of EVOH to be used and less than melting temperature. Thereby, the molecular orientation is aligned in the stretching direction, and the next split processing is facilitated. In addition, a known splitter such as a razor splitter, a needle splitter, a corrugated rough surface splitter, or a file-type splitter can be appropriately used for the split processing.
In addition, in order to make a weather resistance more excellent at the time of EVOH film forming, a ultraviolet absorber, a hindered amine light stabilizer, antioxidant, etc. can be suitably added if desired.

(Split fiber web (D))
In the split fiber nonwoven fabric II, the split fiber web used as the layer (D) is a web made of PVA or a web made of EVOH.
(D) The split fiber web made of PVA that can be used as the layer is the same as the split fiber web made of PVA (A) and (B), and explained in the split fiber web of PVA (A) and (B). It is as follows.
Further, the EVOH split fiber web that can be used as the layer (D) is as described in the EVOH split fiber web (C).

(Production of split fiber nonwoven fabric II)
The split fiber nonwoven fabric II is obtained by dividing the EVOH split fiber web (C) obtained as described above and the PVA split fiber web or EVOH split fiber web (D) vertically through an adhesive layer, It can be manufactured by cross-stacking horizontally.
In the present invention, the split fiber web in the longitudinal direction may be the split fiber web (C) or the split fiber web (D). When the longitudinal split fiber web is the web (C), the web (D) is used as the split fiber web orthogonal to the web (C), and conversely, the longitudinal split fiber web is the web (D). In this case, the web (C) is used as the split fiber web orthogonal to it.
In this invention, it is preferable that the thickness of a split fiber web (C) and a split fiber web (D) is the range of 10-70 micrometers independently, respectively.
In addition, about an adhesive bond layer and a radionuclide capture | acquisition material, it is as having demonstrated in the split fiber nonwoven fabric I mentioned above.

The radionuclide capture net of the present invention thus obtained is useful for protecting agricultural products from contamination by radionuclides such as radiocesium and radiostrontium, decontamination of various pollutants by radionuclides, For example, it is used for the protection of crops from radionuclides, for solids and curtains, and for decontamination of paddy fields, arable land and fields, and decontamination of roads, gutters, schoolyards, grounds, lawns, roofs of houses, walls, Furthermore, it can be used for decontamination of contaminated water as a filter.
The radionuclide trapping net of the present invention is lightweight when processing waste, and the volume can be reduced by reducing the volume.

Next, the aqueous coating agent composition of the present invention will be described.
[Aqueous coating agent composition]
The aqueous coating agent composition of the present invention comprises a PVA-based adhesive and ammonium phosphomolybdate as a radionuclide capturing material, and the aqueous coating agent composition has a radionuclide on the surface of a film or fabric. Used for forming a trapping layer.
In addition, in the aqueous coating material composition of the present invention, in the same manner as the radionuclide capture net, together with ammonium phosphomolybdate, other radionuclide capture materials such as Prussian blue (bitumen) particles, copper hexacyanoferrate (II) Use in combination with at least one radionuclide trapping material selected from supported porous carrier particles, mica particles, zeolite particles, borosilicate zeolite particles, kaolin particles, bentonite particles, microalgae, and ion exchange resins. It is not excluded.

Examples of the radionuclide include radioactive cesium such as cesium 137 and cesium 134, manganese 54, cobalt 60, radioactive strontium, iodine 131, and the like.
In the aqueous coating agent composition, radioactive cesium can be suitably captured.
In the aqueous coating agent composition, the PVA adhesive preferably contains a polyvinyl acetate or polyurethane as an adhesive resin component in a proportion of 50% by mass or less. Such a PVA adhesive is as described in the description of the split fiber nonwoven fabric I.
Moreover, in the said aqueous coating agent composition, it is preferable to contain ammonium phosphomolybdate in the ratio of 0.2-50 mass%.
When a radionuclide capture layer is formed on the surface of a member to be coated such as a film or fabric using the aqueous coating agent composition, it is possible to capture a radionuclide by using a hydrophilic film or fabric as the member to be coated. It is preferable from the viewpoint of layer formation.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
In addition, the quantitative analysis of the capture | acquisition cesium in the split fiber nonwoven fabric containing ammonium phosphomolybdate was performed in accordance with the following method.

<Quantitative analysis of trapped cesium in split fiber nonwoven fabric containing ammonium phosphomolybdate>
As a nonwoven fabric for testing, a 10 cm × 10 cm nonwoven fabric was used, and after immersion for a predetermined time in 50 cm ³ of each cesium chloride aqueous solution having a concentration of 0.1 mg / L, 1.0 mg / L, 10.0 mg / L, and 1000 mg / L, The sample was taken out and dried at room temperature to obtain a sample for analysis.
The sample was completely dissolved in a 1: 1 ratio of aqua regia and water, filtered through A5 filter paper, and the filtrate was analyzed with a flame photometer [Varian, model name “Spectr”. AA55B type]] was used, and the amount of captured cesium was measured at a measurement wavelength: 852.1 nm.

Example 1
(1) Film material As a film material, a PVA film having a polymerization degree of 1700 and a saponification degree of 99.0 mol% or more [made by Kuraray Co., Ltd., trade names “VF-TR5000” and “VF-TR6000”] is used. , For each split fiber nonwoven fabric for vertical web, thickness 50μm x width 138cm (VF-TR5000)
Split fiber nonwoven fabric For horizontal web Thickness 60μm x Width 150cm (VF-TR6000)
Prepared.
(2) Stretching process Using the film material in (1) above, stretching ratio: 5.8 times, stretching temperature: 180 ° C., heat treatment temperature: 220 ° C., winding speed: 60 m / min. A uniaxially stretched web was prepared.
(3) Laminating step While feeding the stretched web obtained in (2) above from the longitudinal and lateral directions with a laminating machine, it is adhered with a PVA adhesive containing ammonium phosphomolybdate, and the processing speed is 20 m / min. Adhesive drying temperature: A split fiber nonwoven fabric having an amount of ammonium phosphomolybdate having a pure content of 3.0 g / m ² was produced under the condition of 140 ° C.
The PVA adhesive containing ammonium phosphomolybdate has a PVA concentration of PVA 8 so that the PVA concentration is 8.0% by mass, the ammonium phosphomolybdate concentration (pure content) is 6.0% by mass, and the water is 86.0% by mass. It was prepared by blending and stirring an aqueous dispersion of ammonium phosphomolybdate in a 5% by mass aqueous solution.
(4) Preparation of cesium aqueous solution for cesium capture amount measurement For measurement of cesium capture amount, a special grade reagent “cesium chloride” manufactured by Wako Pure Chemical Industries, Ltd. is diluted in pure water to prepare a 0.1 mg / L aqueous solution of cesium chloride. And this aqueous solution was used for the split fiber nonwoven fabric immersion.
(5) Test method After preparing 0.01 m ² (10 cm × 10 cm) of a split fiber nonwoven fabric containing 3.0 g / m ² of ammonium phosphomolybdate and immersing in 0.1 mg / L of 50 cm ³ aqueous cesium chloride solution for 1 hour Each of the split fiber nonwoven fabrics was collected, and the amount of cesium trapped in the split fiber nonwoven fabric was measured. Furthermore, the residual cesium concentration of the 50 cm ³ cesium chloride aqueous solution was measured, and the removal rate of cesium was examined.

Example 2
(1) The film material and (2) the stretching step are the same as in Example 1.
(3) In the lamination step, a split fiber nonwoven fabric having an amount of ammonium phosphomolybdate having a pure content of 3.0 g / m ² was produced in the same manner as in Example 1.
As in Example 1, the PVA adhesive containing ammonium phosphomolybdate had a PVA concentration of 8.0 mass%, an ammonium phosphomolybdate concentration (pure content) of 6.0 mass%, and other water of 86.0 mass. %, The aqueous dispersion of phosphomolybdate was mixed with an aqueous 8.5 mass% PVA solution and stirred.
(4) Preparation of cesium aqueous solution for cesium capture amount measurement For measurement of cesium capture amount, a special grade reagent “cesium chloride” manufactured by Wako Pure Chemical Industries, Ltd. is diluted in pure water to prepare a 1.0 mg / L aqueous solution of cesium chloride. And this aqueous solution was used for the split fiber nonwoven fabric immersion.
(5) Test method After preparing 0.01 m ² (10 cm × 10 cm) of a split fiber nonwoven fabric containing 3.0 g / m ² of ammonium phosphomolybdate and immersing in 1.0 mg / L of 50 cm ³ cesium chloride aqueous solution for 1 hour Each of the split fiber nonwoven fabrics was collected, and the amount of cesium trapped in the split fiber nonwoven fabric was measured. Furthermore, the residual cesium concentration of the 50 cm ³ cesium chloride aqueous solution was measured, and the removal rate of cesium was examined.

Example 3
(1) The film raw material and (2) the stretching step are the same as in Example 1. (3) The laminating step is the same as in Example 1 except that the web obtained in (2) above has a pure content of 6. A split fiber nonwoven fabric having an amount of ammonium phosphomolybdate of 0 g / m ² was produced in the same manner as in Example 1. Each condition in the lamination process is shown in Table 1.
The PVA adhesive containing ammonium phosphomolybdate has a PVA concentration of 8.0 mass%, an ammonium phosphomolybdate concentration (pure content) of 12.0 mass%, and other water of 80.0 mass%. An aqueous phosphomolybdate dispersion was mixed in a 5% by mass aqueous solution and stirred.
(4) Preparation of cesium aqueous solution for cesium capture amount measurement For measurement of cesium capture amount, a special grade reagent “cesium chloride” manufactured by Wako Pure Chemical Industries, Ltd. is diluted in pure water to prepare a 0.1 mg / L aqueous solution of cesium chloride. And this aqueous solution was used for the split fiber nonwoven fabric immersion.
(5) Test method After preparing 0.01 g ² (10 cm × 10 cm) of a split fiber nonwoven fabric containing 6.0 g / m ² of ammonium phosphomolybdate and immersing in 0.1 mg / L of 50 cm ³ cesium chloride aqueous solution for 1 hour Each of the split fiber nonwoven fabrics was collected, and the amount of cesium trapped in the split fiber nonwoven fabric was measured. Furthermore, the residual cesium concentration of the 50 cm ³ cesium chloride aqueous solution was measured, and the removal rate of cesium was examined.

Example 4
(1) The film material and (2) the stretching step are the same as in Example 1.
(3) In the lamination step, a split fiber nonwoven fabric having an amount of ammonium phosphomolybdate having a pure content of 6.0 g / m ² was produced in the same manner as in Example 3.
(4) Preparation of cesium aqueous solution for cesium capture amount measurement For measurement of cesium capture amount, a special grade reagent “cesium chloride” manufactured by Wako Pure Chemical Industries, Ltd. is diluted in pure water to prepare a 1.0 mg / L aqueous solution of cesium chloride. And this aqueous solution was used for the split fiber nonwoven fabric immersion.
(5) Test method After preparing 0.01 g ² (10 cm × 10 cm) of a split fiber nonwoven fabric containing 6.0 g / m ² of ammonium phosphomolybdate and immersing in 1.0 mg / L of 50 cm ³ cesium chloride aqueous solution for 1 hour Each of the split fiber nonwoven fabrics was collected, and the amount of cesium trapped in the split fiber nonwoven fabric was measured. Furthermore, the residual cesium concentration of the 50 cm ³ cesium chloride aqueous solution was measured, and the removal rate of cesium was examined.

Example 5
(1) A film raw material, (2) a stretching step, and (3) a lamination step were carried out in the same manner as in Example 1 to produce a split fiber nonwoven fabric.
(4) As the cesium aqueous solution for measuring the amount of cesium trapped, a cesium chloride aqueous solution having a dissolution concentration of 10.0 mg / L was prepared and used.
(5) The test method was prepared by preparing 0.01 m ² (10 cm × 10 cm) of a split fiber nonwoven fabric containing 3.0 g / m ² of ammonium phosphomolybdate and immersing in 10.0 mg / L of 50 cm ³ aqueous cesium chloride solution for 1 hour. After that, each of the split fiber nonwoven fabrics was collected, and the amount of cesium captured by the split fiber nonwoven fabric was measured. Furthermore, the residual cesium concentration of the 50 cm ³ cesium chloride aqueous solution was measured, and the removal rate of cesium was examined.

Example 6
(1) The film material and (2) the stretching step are the same as in Example 1.
(3) In the lamination step, a split fiber nonwoven fabric having an amount of ammonium phosphomolybdate having a pure content of 3.0 g / m ² was produced in the same manner as in Example 1.
(4) Preparation of cesium aqueous solution for measurement of cesium capture amount For measurement of cesium capture amount, a special grade reagent “cesium chloride” manufactured by Wako Pure Chemical Industries, Ltd. is diluted in pure water to prepare a 1000 mg / L aqueous solution of cesium chloride. This aqueous solution was used for soaking a split fiber nonwoven fabric.
(5) Test method After preparing 0.01 m ² (10 cm × 10 cm) of a split fiber nonwoven fabric containing 3.0 g / m ² of ammonium phosphomolybdate and immersing it in a 50 mg ³ cesium chloride aqueous solution of 1000 mg / L for 1 hour, Each of the split fiber nonwoven fabrics was collected, and the amount of cesium captured by the split fiber nonwoven fabric was measured. Furthermore, the residual cesium concentration of the 50 cm ³ cesium chloride aqueous solution was measured, and the removal rate of cesium was examined.

Example 7
(1) The film material and (2) the stretching step are the same as in Example 1.
(3) In the lamination step, a split fiber nonwoven fabric having an amount of ammonium phosphomolybdate having a pure content of 6.0 g / m ² was produced in the same manner as in Example 3.
(4) Preparation of cesium aqueous solution for cesium capture amount measurement For measurement of cesium capture amount, a special grade reagent “Cesium Chloride” manufactured by Wako Pure Chemical Industries, Ltd. is diluted in pure water to prepare 10.0 mg / L aqueous solution of cesium chloride. And this aqueous solution was used for the split fiber nonwoven fabric immersion.
(5) Test method After preparing 0.01 m ² (10 cm × 10 cm) of a split fiber nonwoven fabric containing 6.0 g / m ² of ammonium phosphomolybdate and immersing in 10.0 mg / L of 50 cm ³ aqueous cesium chloride solution for 1 hour Each of the split fiber nonwoven fabrics was collected, and the amount of cesium trapped in the split fiber nonwoven fabric was measured. Furthermore, the residual cesium concentration of the 50 cm ³ cesium chloride aqueous solution was measured, and the removal rate of cesium was examined.

Example 8
A split fiber nonwoven fabric having an amount of ammonium phosphomolybdate having a pure content of 6.0 g / m ² was produced in the same manner as in Example 7 for (1) film raw material, (2) stretching step, and (3) laminating step. .
(4) Preparation of cesium aqueous solution for measurement of cesium capture amount For measurement of cesium capture amount, a special grade reagent “cesium chloride” manufactured by Wako Pure Chemical Industries, Ltd. is diluted in pure water to prepare a 1000 mg / L aqueous solution of cesium chloride. This aqueous solution was used for soaking a split fiber nonwoven fabric.
(5) Test method After preparing 0.01 m ² (10 cm × 10 cm) of a split fiber nonwoven fabric containing 6.0 g / m ² of ammonium phosphomolybdate and immersing it in a 50 mg ³ cesium chloride aqueous solution of 1000 mg / L for 1 hour, Each of the split fiber nonwoven fabrics was collected, and the amount of cesium captured by the split fiber nonwoven fabric was measured. Furthermore, the residual cesium concentration of the 50 cm ³ cesium chloride aqueous solution was measured, and the removal rate of cesium was examined.

Table 1 shows conditions in the stacking steps of Examples 1 to 8 and the reference example as an example in which ammonium phosphomolybdate was not used.
Table 2 shows the physical properties of the split fiber nonwoven fabrics obtained in Examples 1 to 8 and Reference Example.

[Note] Various characteristics in each example were determined according to the following methods.
(1) Thickness of non-woven fabric For a sample of 20 cm × 20 cm, four corners were measured with a micrometer, and the average value was defined as the thickness.
(2) Fabric weight of nonwoven fabric A mass of 1 m ² was measured for a 20 cm × 20 cm sample, and the fabric weight (g / m ² ) was calculated.

<Performance of non-woven fabric>
(3) Tensile strength and tensile elongation About a sample with a width of 2.5 cm and a length of 20 cm, using an autograph [manufactured by Shimadzu Corporation, model name “AGSJ-1KN”] Tensile elongation was measured.
(4) Adhesive strength About the sample of width 2cm and length 20cm, the intensity | strength (adhesion strength) of 45 degree | times was measured using the autograph (above).
(5) Shrinkage resistance According to the following test method, the shrinkage rate was measured in the vertical direction and the horizontal direction, and the shrinkage resistance was evaluated.
Sd-5 shrinkage was determined both in the vertical and horizontal directions. The Sd-5 shrinkage ratio is desirably 3.0% or less.

≪Test method≫
Four test pieces having a width of 4 cm and a length of 50.0 cm were prepared.
(A) The temperature of the dryer (constant temperature machine) is set to 60 ° C. and the temperature is increased.
(B) Put water (room temperature) into a container of an appropriate size, put a test piece whose length has been measured, and soak for 1.0 hour.
(C) Measure the length of the wet specimen. At this time, since it is softened by moisture, it should be properly stretched without being stretched strongly.
(D) Length measurement. Record (W-1).
(E) Put the test pieces after length measurement into a dryer (constant temperature machine) set at 60 ° C. so that they do not overlap each other and dry for 5 hours.
(F) The length of the test piece after drying is measured (D-1).
(G) Repeat (b) to (f) above.
When measuring once a day (one each for W and D), put the test piece after drying and measurement into a plastic bag or the like and store it until before the next dipping.
Assuming that the length of the blank is L ₀ , and each value after the 5th watering and drying is Lw-5 · Ld-5, each shrinkage rate Sw-5 · Sd-5 for the 5th time is
Sw-5 (%) = [(L ₀ -Lw-5) / L ₀ ] × 100
Sd-5 (%) = [(L ₀ -Ld-5) / L ₀ ] × 100
It becomes.

(6) Water absorption rate A sample of 10 cm × 10 cm is allowed to stand for 5 hours under the conditions of 25 ° C. and 65% RH, and then the mass is measured (Ag). Then, after drying for 3 hours with a dryer at 105 ° C., it is allowed to cool for 5 minutes with a desiccator containing a desiccant and the mass is measured (Bg).
From the mass of the sample before and after drying, the water absorption is calculated by the following formula.
Water absorption rate (%) = [(A−B) / B] × 100

  From the results of physical properties shown in Table 2, the mechanical properties of the split fiber nonwoven fabrics obtained in Examples and Reference Examples were not significantly different.

  The test results in Examples 1 to 8 and Reference Example are shown in Table 3 together with other conditions.

  The test data in Table 3 was verified in Tables 4 and 5.

Consideration (1) From the above data, the following can be said from an overview.
Cs trapped by ammonium phosphomolybdate in the split fiber nonwoven fabric is trapped as the amount of ammonium phosphomolybdate increases and the Cs concentration in CsCl water increases.
(2) FIG. 1 is a graph with [E] = log [C] in Table 4 on the horizontal axis and [F] = log [D] on the vertical axis. From FIG. It can be seen that Cs trapping amount and [ammonium phosphomolybdate content of non-woven fabric × Cs concentration in CsCl water] have a proportional relationship when logarithm of each is taken.
(3) Therefore, according to the radioactive contamination concentration and the object, the split fiber nonwoven fabric according to the ammonium phosphomolybdate concentration and the usage (software) suitable for it are required.
(4) As is clear from Table 5, it can be seen that cesium can be removed at a high removal rate even when a low-concentration cesium chloride aqueous solution is used.

  The radionuclide capture net of the present invention is suitably used for protection of agricultural products from contamination by radionuclides such as radiocesium, radiostrontium, radiocobalt, and radiomanganese, and decontamination of various contaminants by radionuclides. It is expected to be used as a filter material especially in the treatment of radionuclide contaminated water. In addition, the aqueous coating agent composition of the present invention can form a radionuclide capturing layer on the surface of a film or fabric, and can provide various radionuclide capturing members.

Claims (5)

A split fiber nonwoven fabric having a two-layer laminated structure in which split fiber webs (A) and (B) made of polyvinyl alcohol are vertically and horizontally orthogonally stacked via a polyvinyl alcohol adhesive layer, adhesive constituting the adhesive layer, adhesion with containing at least 50 wt% polyvinyl alcohol as the resin component, Ri polyvinyl alcohol-based adhesive der containing at least ammonium phosphomolybdate as radionuclide capturing material, the polyvinyl alcohol-based adhesive phosphorus content of ammonium molybdate, characterized in 0.1~25g / m ² der Rukoto respect to the nonwoven fabric, radionuclide capture net being. A split fiber web (C) made of an ethylene-vinyl alcohol copolymer and a split fiber web made of polyvinyl alcohol or a split fiber web (D) made of an ethylene-vinyl alcohol copolymer are vertically arranged through an adhesive layer. A split fiber non-woven fabric having a two-layer laminated structure that is orthogonally laminated horizontally, and the adhesive constituting the adhesive layer contains 50% by mass or more of polyvinyl alcohol as an adhesive resin component, and a radionuclide trapping material At least phosphorus Ri polyvinyl alcohol-based adhesive der containing ammonium molybdate as the content of phosphoric ammonium molybdate in the polyvinyl alcohol-based adhesive, Ru 0.1~25g / m ² der respect to the non-woven fabric A radionuclide capture net characterized by that. The radionuclide is a radioactive cesium, radioactive strontium, radioactive cobalt, radionuclide capture net according to claim 1 or 2 is at least one radioactive manganese. The radionuclide trapping net according to any one of claims 1 to 3 , wherein the polyvinyl alcohol-based adhesive is an aqueous adhesive. The radionuclide trapping net according to any one of claims 1 to 4 , wherein the polyvinyl alcohol-based adhesive contains a polyvinyl acetate-based or polyurethane-based adhesive resin component at a ratio of 50% by mass or less.

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