JP2014224762A - Fiber structure for adsorbing cesium ion and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fiber structure having a cesium ion absorbent fixed firmly thereto, and having excellent cesium ion adsorption ability generating little falling, and to provide a manufacturing method thereof.SOLUTION: In a fiber structure for adsorbing cesium ion, which is a fiber structure including fibers in which two or more kinds of fibers having a melting point difference of 30°C or more and/or polymers having a melting point difference of 30°C or more are adjacent or form a core-sheath structure, a cesium ion absorbent is fixed with a low melting-point component of the fiber and a binder.

Description

  The present invention relates to a fiber structure for adsorbing cesium ions with less cesium ion adsorbent falling off and a method for producing the same.

  Zeolite and Prussian blue are known to have an excellent ability to adsorb cesium ions, which are radioactive elements. After the accident at TEPCO's Fukushima Daiichi Nuclear Power Station that occurred following the Tohoku-Pacific Ocean Earthquake, it has attracted a great deal of attention as a cesium ion adsorbent because of its performance. Currently, the radioactivity decontamination business is advancing. There is a growing need as an adsorbing material in which these are supported on a fiber material.

  Various adsorbents can be supported on the fiber material by rolling the adsorbent as it is and then rolling and supporting it. Adhesion method supporting various adsorbents in combination with a primary binder (binder). Spray drying. The method etc. are known (for example, refer patent documents 1-3). In addition, in order to prevent the adsorbed adsorbent from falling off, a method of covering the surface of the fiber material by treating the adsorbent with an adhesive binder such as polyurethane, polyester, or polyacrylate as a secondary binder after adsorbing the adsorbent. It is known (see, for example, Patent Document 1).

  However, in the rolling method, the adhesion method, the spray drying method, etc., the target adsorbing performance can be obtained because the adsorbent concentration on the surface of the obtained fiber material cannot be increased or the adsorbent is covered with the binder. There was a problem such as not being able to. Furthermore, there is a possibility that environmental pollution may be expanded due to the adsorbent being carried off. In particular, the fiber structure for adsorbing cesium ions has a problem that a serious situation may occur because the adsorbent that adsorbs radioactive cesium at a high concentration from the fiber structure may cause further environmental pollution. Despite the further decline in cesium ion adsorption capacity to prevent such falling off, the amount of adhesion of binder used for the purpose of primary binder and secondary binder is unavoidable. At present, it is necessary to adhere to the above.

Special table 2000-506827 gazette JP 2001-164326 A JP 2000-237604 A

  An object of the present invention is to eliminate the drawbacks of the prior art as described above, and the present invention is a fiber structure having a cesium ion adsorbent firmly fixed and having excellent cesium ion adsorbing ability with very little dropout. And a manufacturing method thereof.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have used a specific fiber material and a binder when fixing the cesium ion adsorbent to the fiber structure, preferably a specific cesium ion adsorbent, The present inventors have found that a fiber structure having excellent cesium ion adsorption capacity and very little detachment of the adsorbent is obtained by heat-sealing treatment at a specific temperature.
That is, the gist of the present invention is the following (1) to (8).
(1) A fiber structure comprising two or more kinds of fibers having a melting point difference of 30 ° C. or more and / or a fiber having a polymer having an adjacent melting point difference or a melting point difference of 30 ° C. or more, and having a core-sheath structure. A fiber structure for adsorbing cesium, wherein an adsorbent is fixed with a low melting point component of the fiber and a binder.
(2) The fiber structure for adsorbing cesium ions according to (1), wherein the cesium ion adsorbent is a Prussian blue type complex.
(3) The binder is composed of at least one resin selected from the group consisting of polyester resins, acrylic resins, vinyl acetate resins, polyurethane resins, and silicon resins (1) ) The fiber structure for adsorbing cesium ions.
(4) The fibrous structure for cesium ion adsorption according to any one of (1) to (3), wherein the amount of the binder fixed is 10 to 100 parts by mass with respect to 100 parts by mass of the cesium ion adsorbent. .
(5) Two or more types of fibers having a melting point difference of 30 ° C. or higher and / or fibers having a melting point difference of 30 ° C. or higher adjacent to each other or having a core-sheath structure are polyester fibers, polyamide fibers, The fiber structure for adsorbing cesium ions according to any one of (1) to (4), wherein the fiber structure is composed of one or more fibers selected from the group consisting of polyolefin fibers and polylactic acid fibers .
(6) The low melting point component of the fiber in which the two or more kinds of fibers having a melting point difference of 30 ° C. or higher and / or the polymer having a melting point difference of 30 ° C. or higher has an adjacent or core-sheath structure is 5% by mass or more. The fiber structure for cesium ion adsorption according to any one of (1) to (5), which is contained.
(7) The melting point of the low melting point component of the fiber in which two or more kinds of fibers having a melting point difference of 30 ° C. or more and / or a polymer having a melting point difference of 30 ° C. or more are adjacent or in a core-sheath structure is 110 to 110 ° C. It is 190 degreeC, The fiber structure for cesium ion adsorption | suction in any one of (1)-(6) characterized by the above-mentioned.
(8) A cesium ion adsorbent for a fiber structure containing two or more kinds of fibers having a melting point difference of 30 ° C. or more and / or fibers having a polymer having a melting point difference of 30 ° C. or more adjacent or in a core-sheath structure. And a dispersion containing the binder, and further heat-treating at 130 to 200 ° C. The method for producing a fiber structure for adsorbing cesium ions according to any one of (1) to (7).

  The fiber structure for adsorbing cesium ions of the present invention includes two or more kinds of fibers having a melting point difference of 30 ° C. or more and / or fibers having a polymer sheath having a melting point difference of 30 ° C. or more and an adjacent or core-sheath structure. By giving the cesium ion adsorbent and binder to the fiber structure and then performing a specific heat fusion treatment, the cesium ion adsorbent is firmly fixed by the synergistic effect of the heat fusible fiber and the binder, It is possible to provide a fiber structure in which the adsorbent excellent in cesium adsorption performance with a small amount of binder is very small.

  Hereinafter, the present invention will be described in detail.

  The fiber structure of the present invention needs to contain two or more kinds of fibers having a melting point difference of 30 ° C. or more and / or fibers in which a polymer having a melting point difference of 30 ° C. or more has an adjacent or core-sheath structure. is there.

  The combination of two or more kinds of fibers having a melting point difference of 30 ° C. or more and / or a fiber having a melting point difference of 30 ° C. or more and a fiber having an adjacent or core-sheath structure is not particularly limited, but for example, polyethylene terephthalate, poly Polyester fibers with different melting points such as butylene terephthalate and polylactic acid fibers, Polyamide fibers with different melting points such as polyamide 6 and polyamide 66, Polyester fibers and polyethylene fibers, Polyester fibers and polypropylene fibers, Polyamide fibers and polyethylene fibers, Polyamide fibers and polypropylene fibers , Polyester fibers copolymerized with polyester fiber and lower melting point, thermoplastic fibers and natural fibers such as cellulosic fibers and animal fibers, thermoplastic fibers and activated carbon fibers, or a plurality of polymers constituting the fibers The side Isaido, fibers and a composite structure, such as core-sheath structure, such as those conjugated one or more like the natural fibers. In the present invention, as will be described later, a fiber having a low melting point or a fiber containing a polymer having a low melting point may be referred to as a heat-fusible fiber.

  The difference in melting point of 30 ° C. or more refers to the difference between the melting points of two or more resins in the case of two or more types of fibers, and the melting point of the different resins in the case of fibers having a composite structure composed of resins having different melting points. The difference refers to a difference between the highest melting point and the lowest melting point in the case of a combination of fibers made of a single resin and / or a fiber having a composite structure made of resins having different melting points.

  A cesium ion adsorbent described below and a fiber structure containing fibers having two or more kinds of fibers having a melting point difference of 30 ° C. or more and / or a polymer having a melting point difference of 30 ° C. or more having an adjacent or core-sheath structure After the binder is applied, the fiber or polymer on the low melting point side (hereinafter sometimes referred to as a low melting point component) is heated to a predetermined heat fusing temperature, so that the synergistic effect of the fusing property due to softening and the binder. Accordingly, it is possible to provide a fiber structure with a very small amount of binder and a very small amount of adsorbent with excellent cesium ion adsorption performance.

  If the melting point difference is less than 30 ° C., the temperature difference is small, so that the low melting point fiber or the low melting point polymer retains the fiber structure at the time of fusing due to processing temperature fluctuations. This is not preferable because it also dissolves and decreases the contact area with the treated water containing cesium ions, resulting in a decrease in adsorption capacity.

  For polyester fiber, polyamide fiber, polyolefin fiber, etc., from the viewpoint of fixing of cesium ion adsorbent, the surface is subjected to laser treatment, ultraviolet irradiation, plasma treatment, electron beam treatment, etc., hydroxyl group, sulfate group, etc. Those having the functional group are preferably introduced.

  The form of the fiber in which two or more kinds of fibers having a melting point difference of 30 ° C. or higher and / or a polymer having a melting point difference of 30 ° C. or higher in the present invention has an adjacent or core-sheath structure is not particularly limited. Examples thereof include short fibers, false twisted yarns, spun yarns, and slit yarns.

  Furthermore, the melting point of the low melting point component of the fiber in which two or more kinds of fibers having a melting point difference of 30 ° C. or more and / or a polymer having a melting point difference of 30 ° C. or more are adjacent or in a core-sheath structure is 110 to 190 ° C. Is preferred. As will be described later, since it is necessary to perform heat fusion treatment when fixing the cesium ion adsorbent to the fiber structure of the present invention, the melting point of the low melting point component is set to 110 to 190 ° C. It is preferable that the fiber structure can keep the form better in the dressing treatment and has higher thermal stability during storage.

  Mixing ratio of two or more kinds of fibers having a melting point difference of 30 ° C. or more and / or a fiber having a melting point difference of 30 ° C. or more and a fiber having a low melting point and a fiber having a low melting point adjacent to or in a core-sheath structure Is preferably 5% by mass or more of the fiber structure, more preferably 10% by mass or more, still more preferably 10 to 90% by mass, and still more preferably 20 to 80% by mass. By adjusting the mixing ratio to 5% by mass or more, the adhesive strength of the cesium ion adsorbent due to the low melting point component becomes appropriate, and the voids of the fiber structure can be favorably retained during the cesium ion adsorbent application treatment. Further, it is preferable that the gap of the fiber structure is closed when the low melting point component is dissolved, and the contact area with the treated water containing cesium ions is reduced.

  The fiber structure of the present invention is not particularly limited as long as it is a structure made of fibers, and examples thereof include forms such as molded articles made of cotton, yarns, woven and knitted fabrics, nonwoven fabrics, and papers. Among these, non-woven fabrics are particularly preferable from the viewpoint that the cesium ion adsorbent is favorably retained by the high voids of the fiber structure.

  The nonwoven fabric is composed of two or more kinds of fibers having a melting point difference of 30 ° C. or more and / or fibers in which a polymer having a melting point difference of 30 ° C. or more has an adjacent or core-sheath structure, that is, a low melting point component and a high melting point component. It can manufacture from a fiber web by a well-known method. For example, the fiber web creation method may be wet or dry, and any of the known fiber web creation methods such as a card method, an airlaid method, a hydroentanglement method, and a needle punch method can be applied. In order to efficiently adsorb cesium ions dissolved in water, a short fiber nonwoven fabric having a high porosity is preferable.

  Although the single fiber fineness of the fiber which comprises the fiber structure used by this invention is not specifically limited, From a sticking viewpoint of a cesium ion adsorption agent, 3 dtex or less is preferable and 2 dtex or less is more preferable. By setting the fineness of the single fiber fineness to 3 dtex or less, the surface area including the voids of the fiber structure is further improved, so that it is estimated that the loading ratio of the cesium ion adsorbent is further improved.

  The cesium ion adsorbent of the present invention is not particularly limited as long as it adsorbs cesium ions, and examples thereof include a cesium ion adsorbing complex and zeolite. Examples of the cesium ion-adsorptive complex include Prussian blue complex and phthalocyanine complex.

Prussian blue-type complexes have the general formula _{A x M [Fe (CN)} 6] y · zH 2 O ( In the formula, A is a cation, M represents a metal atom) is a complex represented by. Examples of the cation for A include ammonium ions. The metal atom of M is a group consisting of vanadium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, copper, silver, zinc, lanthanum, europium, gadolinium, lutetium, barium, strontium, and calcium. One kind or two or more kinds of metal atoms selected from the above are exemplified. Among the combinations described above, Fe ₄ [Fe (CN) ₆ ] ₃ and FeNH ₄ [Fe (CN) ₆ ] are particularly preferable from the viewpoints of cesium ion adsorption ability and selectivity of cesium ions in the coexistence state of foreign substances. .

  The average primary particle size of the Prussian blue type complex is not particularly limited, but is preferably 0.001 to 100 μm, more preferably 0.001 to 10 μm, and further preferably 0.001 to 1 μm, from the viewpoints of cesium ion adsorption ability and processing suitability. Preferably, 0.001 to 0.05 μm is more preferable.

  Examples of the phthalocyanine type complex include copper phthalocyanine, chlorinated copper phthalocyanine, brominated chlorinated copper phthalocyanine, and aluminum phthalocyanine. More specifically, examples of the copper phthalocyanine include Pigment Blue15, Pigment Blue15: 3, Pigment Blue76, Ingrain Blue1, and Direct Blue86. Examples of the chlorinated copper phthalocyanine include Pigment Green 7. As a brominated chlorinated copper phthalocyanine, Pigment Green 58 is exemplified.

  Zeolite is a general term for aluminosilicates having relatively large voids in the crystal structure and is not particularly limited, and examples thereof include crystalline aluminosilicates, metallosilicates, aluminophosphates, silicaaluminophosphates, and the like.

  The average primary particle diameter of zeolite is not particularly limited, but is preferably 0.1 to 100 μm, more preferably 1.0 to 50 μm, and still more preferably 1.0 to 30 μm, from the viewpoint of cesium ion adsorption ability and processing suitability.

  The fixed amount of the cesium ion adsorbent of the present invention is preferably 0.1 to 10% by mass, preferably 0.1 to 5% by mass with respect to the fiber material constituting the fiber structure, from the viewpoint of reducing the falling off of the cesium ion adsorbent. % Is more preferable.

  The binder of the present invention is not particularly limited as long as the cesium ion adsorbent is fixed to the fiber structure, but from the viewpoint of adhesion to both the fiber material and the cesium ion adsorbent, a polyester resin, an acrylic resin, One or more kinds of resins selected from the group consisting of vinyl acetate resins, polyurethane resins, and silicon resins are preferable. Among them, they are dispersed in water to form fine particles having a particle size of about 0.05 to 1.0 μm by an emulsion polymerization method. Emulsion resin is preferred.

  The binder fixing amount of the present invention is preferably 10 to 100 parts by mass with respect to 100 parts by mass of the cesium ion adsorbent, from the viewpoint of improvement of the cesium ion adsorption amount and reduction of the cesium ion adsorbent. A mass part is more preferable, and a 25-60 mass part is still more preferable.

  In the fiber structure of the present invention, by fixing the cesium ion adsorbent to a fiber structure containing a heat-fusible fiber or the like, it becomes possible to reduce the amount of the binder fixed as compared with the conventional adhesive method or the like. Therefore, excellent cesium ion adsorption ability can be exhibited while preventing the cesium ion adsorbent from falling off.

  The cesium ion adsorption amount of the present invention is preferably 0.5 mg / g or more, more preferably 0.7 mg / g, more preferably 1.0 mg / g from the viewpoint of volume reduction of radioactive waste. g is more preferable, and 1.2 mg / g is particularly preferable.

  The fixing amount of the cesium ion adsorbent of the present invention is preferably 0.1 to 10% by mass with respect to the fiber material constituting the fiber structure from the viewpoint of fading and liquid contamination reduction, and adsorption after cesium ion adsorption 0.1-4 mass% is more preferable from a viewpoint of suppression of the radiation dose of a material.

  The amount of the cesium ion adsorbent falling from the fiber structure in the present invention is preferably 25 ppm or less, more preferably 15 ppm or less, still more preferably 5 ppm or less, and particularly preferably 3 ppm or less. By setting the drop-off rate to 25 ppm or less, the adsorbent that adsorbs cesium ions from the fiber structure of the present invention is extremely reduced, so that the adsorbed radioactive cesium ions flow out and diffuse into the environment. Can prevent the risk of excessive contamination.

  Below, the nonwoven fabric is mentioned as an example and the manufacturing method of the fiber structure for cesium ion adsorption | suction of this invention is demonstrated.

  The fiber structure (nonwoven fabric) production method of the present invention is a fiber in which two or more kinds of fibers having a melting point difference of 30 ° C. or higher and / or a polymer having a melting point difference of 30 ° C. or higher has an adjacent or core-sheath structure. Are mixed to form a nonwoven fabric by a known fiber web creation method such as the card method, airlaid method, hydroentanglement method, needle punch method, or the like.

  Next, after a dispersion liquid in which the cesium ion adsorbent and the binder are dispersed is applied to the nonwoven fabric, a heat-sealing treatment at 130 to 200 ° C. is performed.

  The dispersion in which the cesium ion adsorbent and the binder are dispersed is preferably a dispersion in which a predetermined amount of cesium ion adsorbent and binder is dispersed in water. Furthermore, from the viewpoint of suitably maintaining the structure of the cesium ion adsorbent, particularly the Prussian blue type complex, the pH of the aqueous dispersion is preferably 7 or less. In addition, in order to prevent aggregation of the cesium ion adsorbent and the binder, the dispersion preferably uses a surfactant as a dispersant.

  Dispersion application / heat fusion treatment method is a pad-heat treatment method in which a fiber structure is immersed in the dispersion liquid and then squeezed with a mangle and then subjected to heat fusion treatment in a spread form with a tenter or the like. Spray-heat fusion treatment method in which heat treatment is performed in the same manner as above after spraying, print-heat treatment method, coating-heat treatment method in which dispersion is thickened and printed or coated and then heat fusion treatment is carried out in the same manner as above These known methods can be appropriately selected.

  The heat fusion treatment temperature is required to be 130 to 200 ° C., and it is more preferable to select 20 ° C. or higher with respect to the melting point of the low melting point component of the fiber material constituting the fiber structure. A temperature of 130 to 200 ° C. is preferable because the cesium ion adsorbent is sufficiently fixed and uneven film formation due to bumping due to a rapid temperature rise of the dispersion can be suppressed.

  In the present invention, from the viewpoint of preventing the cesium ion adsorbent from falling off, it is preferable to perform a soaping treatment or a water washing treatment with a surfactant after applying the cesium ion adsorbent and the binder.

  Next, the present invention will be specifically described with reference to examples. In addition, this invention is not limited to the Example shown below.

  The evaluation method of the fiber structure for cesium ion adsorption of this invention in an Example and a comparative example is as follows.

1. Cesium ion adsorbent loading rate After the ashing treatment at 600 ° C. for 30 minutes, the fiber structure to which the cesium ion adsorbent is fixed is completely dissolved in aqua regia, and the amount of iron in the aqueous solution is analyzed by ICP emission spectroscopy. To determine the loading rate (%) per unit mass of the fiber structure. In the examples and comparative examples, the conversion from the iron amount to the cesium ion adsorbent amount was performed based on the following molecular formula 1.
Fe ₄ [Fe (CN) ₆ ] ₃ ... (molecular formula 1)
Cesium ion adsorbent loading rate (%) = (Cesium ion adsorbent (g) / fiber structure amount (g)) × 100

2. Binder adhesion rate (%)
10 cm × 10 cm cesium ion adsorbent after drying at 105 ° C. for 2 hours, fiber structure after binder application treatment (after processing), mass difference between fiber structure before processing (before processing) and the above cesium It calculated by the following formula using the amount of ion adsorbent supported.
Binder fixation rate (%) = ((mass after processing (g) −mass before processing (g) −cesium ion adsorbent carrying amount (g)) / mass after processing (g)) × 100

3. Fixing ratio of binder / cesium ion adsorbent The fixing ratio calculated in 1 and 2 above was used to calculate from the following formula.
Fixing ratio = Binder fixing rate (%) / Cesium ion adsorbent loading rate (%)

4). Cesium ion adsorption amount Into a 120 ml vial, 100 ml of cesium chloride aqueous solution with a cesium ion concentration of 10 ppm and 0.2 g of fiber structure (solid-liquid ratio (solid: liquid) = 1: 500) were shaken (Taitech Co., Ltd.). Using a company-made Bioshaker BR-300L), the shaking treatment was performed at 25 ° C. and 120 rpm for 24 hours. Cesium ion concentration in the treatment solution before and after shaking treatment was quantified by ICP-MS (measured in accordance with JIS K 01025.5 (2008) and JIS K 0133 (2000)), and 1 g of fiber structure The amount of adsorbed cesium ions per mg (mg) was calculated. In addition, the adsorption amount of cesium ion made 0.5 mg / g or more the pass.

5. Dropout amount of cesium ion adsorbent 100 ml of cesium chloride aqueous solution with 10 ppm cesium ion concentration and 5 g of fiber structure were put into a 120 ml vial (solid-liquid ratio (solid: liquid) = 1: 20) and shaker (Tytec) JIS K0102 38.1.2 and 38.3 (2008) were used to determine the amount of cyanide compound in the treatment solution after being shaken at 25 ° C. and 120 rpm for 24 hours using Bio Shaker BR-300L, Inc. The amount of cesium ion adsorbent (ppm) dropped in the treatment liquid was calculated based on the molecular formula 1 described above. The drop-off rate was 25 ppm or less.

Example 1
Core-sheath composite fiber (trade name “Melty 4080”, manufactured by Unitika Ltd.) with a core component of polyethylene terephthalate (melting point: 255 ° C.) and a sheath component of copolymer polyethylene terephthalate (melting point: 110 ° C.), fineness 2.2 dtex, fiber length 51 mm) 20% by mass, polyethylene terephthalate single fiber as non-fusible fiber (trade name “Unitika ester” manufactured by Unitika Ltd., melting point 255 ° C., fineness 2.2 dtex, fiber length 51 mm) 80 mass % Was mixed uniformly to obtain a parallel card web. The web was laminated by a known method using a cross wrapper, and after being drafted with a drafter, needle punching was performed to obtain a nonwoven fabric having a basis weight of 200 g / m ² .

Next, the nonwoven fabric is subjected to padding treatment with a dispersion liquid having the following prescription 1, and wet-pickup is applied at 150 ° C. for 6 minutes with a pin tenter so that the wet pick-up is 150% by mass. The fiber structure for cesium ion adsorption | suction of this invention was obtained.
(Prescription 1)
Prussian blue (Fe ₄ [Fe (CN) ₆ ] ₃ manufactured by Kanto Chemical Co., Ltd., hydrophobic / low purity solid content 11%, average primary particle size 0.01 μm) 100 g / L
Acrylic binder (High Resin TS1686, solid content 25% by mass, manufactured by Takamatsu Yushi Co., Ltd.) 40 g / L
Nonionic surfactant (Matsumoto Yushi Seiyaku Co., Ltd. Actinol R100) 2g / L

Example 2
A fiber structure for cesium ion adsorption according to the present invention was obtained in the same manner as in Example 1 except that the formulation 1 of Example 1 was changed to the following formulation 2.
(Prescription 2)
Prussian blue (Fe ₄ [Fe (CN) ₆ ] ₃ manufactured by Kanto Chemical Co., Ltd., hydrophobic / low purity solid content 11%, average primary particle size 0.01 μm) 100 g / L
Acrylic binder (High Resin TS1686, solid content 25% by mass, manufactured by Takamatsu Yushi Co., Ltd.) 14 g / L
Nonionic surfactant (Matsumoto Yushi Seiyaku Co., Ltd. Actinol R100) 2g / L

Example 3
A fiber structure for adsorbing cesium ions of the present invention was obtained in the same manner as in Example 1 except that the ratio of the heat-fusible fiber and the non-fusible fiber in Example 1 was changed to 90:10.

Example 4
The heat-fusible fiber of Example 1 is a polyethylene terephthalate / copolymerized polyethylene terephthalate core-sheath composite fiber (trade name “Cassven 7080” manufactured by Unitika Ltd., core melting point 255 ° C., sheath melting point 160 ° C., fineness 2.2 dtex, fiber length. 51 mm), and further, the heat fusion treatment conditions were changed to a temperature of 180 ° C. for 4 minutes to obtain a fiber structure for cesium ion adsorption according to the present invention in the same manner as in Example 1.

Example 5
The heat-fusible fiber of Example 1 is a polyethylene terephthalate / polyethylene core-sheath composite fiber (trade name “Melty 6080” manufactured by Unitika Ltd., core melting point 255 ° C., sheath melting point 130 ° C., fineness 2.2 dtex, fiber length 51 mm). The fiber structure for adsorbing cesium ions of the present invention was obtained in the same manner as in Example 1 except that the heat fusion treatment conditions were changed to 150 ° C. for 5 minutes.

Example 6
In Example 1, a cesium ion-adsorbing fiber structure of the present invention was obtained in the same manner as in Example 1 except that non-fusible fibers were not used.

Example 7
A fiber structure for cesium ion adsorption according to the present invention was obtained in the same manner as in Example 1 except that the formulation 1 of Example 1 was changed to the following formulation 3.
(Prescription 3)
Prussian blue (Fe ₄ [Fe (CN) ₆ ] ₃ manufactured by Kanto Chemical Co., Ltd., hydrophobic / low purity solid content 11%, average primary particle size 0.01 μm) 100 g / L
Acrylic binder (High Resin TS1686, solid content 25% by mass, manufactured by Takamatsu Yushi Co., Ltd.) 60 g / L
Nonionic surfactant (Matsumoto Yushi Seiyaku Co., Ltd. Actinol R100) 2g / L

Example 8
A fiber structure for adsorbing cesium ions of the present invention was obtained in the same manner as in Example 1 except that the formulation 1 of Example 1 was changed to the following formulation 4.
(Prescription 4)
Prussian blue (Fe ₄ [Fe (CN) ₆ ] ₃ manufactured by Kanto Chemical Co., Ltd., hydrophobic / low purity solid content 11%, average primary particle size 0.01 μm) 100 g / L
Acrylic binder (High Resin TS1686, solid content 25% by mass, manufactured by Takamatsu Yushi Co., Ltd.) 8 g / L
Nonionic surfactant (Matsumoto Yushi Seiyaku Co., Ltd. Actinol R100) 2g / L

Example 9
In Example 1, the fiber structure for cesium ion adsorption of the present invention was obtained in the same manner as in Example 1 except that the heat fusion treatment conditions were changed to a temperature of 110 ° C. for 8 minutes.

Example 10
In Example 4, the fiber structure for adsorbing cesium ions of the present invention was obtained in the same manner as in Example 1 except that the heat fusion treatment conditions were changed to a temperature of 210 ° C. for 3 minutes.

Example 11
A fiber structure for cesium ion adsorption according to the present invention was obtained in the same manner as in Example 1 except that the formulation 1 of Example 1 was changed to the following formulation 5.
(Prescription 5)
Prussian blue (Fe ₄ [Fe (CN) ₆ ] ₃ manufactured by Kanto Chemical Co., Ltd., hydrophobic / low purity solid content 11%, average primary particle size 0.01 μm) 100 g / L
Melamine Binder (Miki Riken Co., Ltd. Becamine PM60 solid content 60% by mass)
18g / L
Catalyst (catalyst 376, pure mass 40% by mass, manufactured by Miki Riken Co., Ltd.) 2g / L
Nonionic surfactant (Matsumoto Yushi Seiyaku Co., Ltd. Actinol R100) 2g / L

Comparative Example 1
A fiber structure for adsorbing cesium ions was obtained in the same manner as in Example 1 except that no heat-fusible fiber was used.

Comparative Example 2
Except not using a binder, it carried out similarly to Example 2, and obtained the fiber structure for cesium ion adsorption | suction.

  Table 1 shows the evaluation results of the fiber structures for adsorbing cesium ions obtained in the above Examples and Comparative Examples.

As is apparent from Table 1, the fiber structure for cesium ion adsorption of Examples 1 to 11 of the present invention has a specific heat after imparting a cesium ion adsorbent and a binder to the nonwoven fabric containing the heat-fusible fiber. Due to the fusion process, the cesium ion adsorbent is firmly fixed by the synergistic effect of the heat-fusible fiber and the binder, the binder fixation amount is suppressed, and the cesium ion adsorption ability is excellent, and the adsorbent is removed. There were very few fiber structures. In particular, Examples 1 to 6, in which the binder type and amount, heat fusion treatment conditions, and the like were optimized, had a high cesium ion adsorption amount and a very small amount of adsorbent dropout compared to the adsorbent loading amount. there were. In Example 7, since the amount of the binder with respect to the adsorbent was relatively large, the cesium ion adsorption ability was a constant level. In Example 8, since the amount of the binder with respect to the adsorbent was relatively small, the adsorption capacity of the cesium ion was sufficient, but the amount of the adsorbent falling off was constant. In Example 9, since the heat fusion treatment temperature was the same as the melting point of the heat-fusible fiber, the amount of adsorbent falling off was constant, and in Example 10, the heat-fusing treatment temperature was that of the heat-fusible fiber. Since the melting point was greatly exceeded, the ability to adsorb cesium ions reached a certain level due to non-uniform film formation. In Example 11, since melamine was used as a binder, the ability to adsorb cesium ions became a certain level from the viewpoint of the balance of adhesion to both the fiber material and the cesium ion adsorbent.
On the other hand, since Comparative Example 1 did not use the heat-fusible fiber, Comparative Example 2 did not give a binder, and thus did not satisfy the prevention of the cesium ion adsorbent from falling off.

Claims (8)

A fiber structure comprising two or more kinds of fibers having a melting point difference of 30 ° C. or more and / or a fiber having a polymer having a melting point difference of 30 ° C. or more adjacent or having a core-sheath structure, A fiber structure for adsorbing cesium ions, which is fixed with a low melting point component of the fiber and a binder.   The fiber structure for adsorbing cesium ions according to claim 1, wherein the cesium ion adsorbent is a Prussian blue complex.   The said binder is comprised with 1 or more types of resin selected from the group which consists of a polyester-type resin, an acrylic resin, a vinyl acetate type resin, a polyurethane-type resin, and a silicon-type resin, It is characterized by the above-mentioned. Fiber structure for cesium ion adsorption.   The fiber structure for cesium ion adsorption according to any one of claims 1 to 3, wherein the amount of the binder fixed is 10 to 100 parts by mass with respect to 100 parts by mass of the cesium ion adsorbent.   The two or more types of fibers having a melting point difference of 30 ° C. or higher and / or the fibers having a core-sheath structure adjacent to the polymer having a melting point difference of 30 ° C. or higher are polyester fiber, polyamide fiber, polyolefin fiber The fiber structure for adsorbing cesium ions according to any one of claims 1 to 4, wherein the fiber structure is composed of one or more fibers selected from the group consisting of polylactic acid fibers.   5% by mass or more of the low melting point component of the fiber in which the two or more kinds of fibers having a melting point difference of 30 ° C. or higher and / or the polymer having a melting point difference of 30 ° C. or higher is adjacent or has a core-sheath structure is included. The fiber structure for cesium ion adsorption according to any one of claims 1 to 5, wherein   The melting point of the low melting point component of the fiber in which the two or more kinds of fibers having a melting point difference of 30 ° C. or more and / or the polymer having a melting point difference of 30 ° C. or more are adjacent or in a core-sheath structure is 110 to 190 ° C. The fiber structure for adsorbing cesium ions according to any one of claims 1 to 6, wherein the fiber structure is used for adsorbing cesium ions. A cesium ion adsorbent and a binder are added to a fiber structure containing two or more kinds of fibers having a melting point difference of 30 ° C. or more and / or fibers having a polymer having a melting point difference of 30 ° C. or more adjacent to each other or a core-sheath structure. The method for producing a fiber structure for adsorbing cesium ions according to any one of claims 1 to 7, wherein a dispersion liquid containing the dispersion liquid is applied and further heat-sealing treatment at 130 to 200 ° C is performed.