WO2013027525A1 - SILVER NANOPARTICLE COMPOSITE, SILVER NANOPARTICLE COMPOSITE SUSPENSION USING THIS, COMPOSITION FOR γ-RAY-SENSITIVE SENSOR FORMATION AND γ-RAY SENSITIVE SENSOR, AND METHOD FOR MANUFACTURING SILVER NANOPARTICLE COMPOSITE - Google Patents

SILVER NANOPARTICLE COMPOSITE, SILVER NANOPARTICLE COMPOSITE SUSPENSION USING THIS, COMPOSITION FOR γ-RAY-SENSITIVE SENSOR FORMATION AND γ-RAY SENSITIVE SENSOR, AND METHOD FOR MANUFACTURING SILVER NANOPARTICLE COMPOSITE Download PDF

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WO2013027525A1
WO2013027525A1 PCT/JP2012/068677 JP2012068677W WO2013027525A1 WO 2013027525 A1 WO2013027525 A1 WO 2013027525A1 JP 2012068677 W JP2012068677 W JP 2012068677W WO 2013027525 A1 WO2013027525 A1 WO 2013027525A1
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nanoparticle composite
silver nanoparticles
silver nanoparticle
metal oxide
triangular
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PCT/JP2012/068677
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French (fr)
Japanese (ja)
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榮希 足立
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国立大学法人東北大学
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/05—Metallic powder characterised by the size or surface area of the particles
    • B22F1/054—Nanosized particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/05—Metallic powder characterised by the size or surface area of the particles
    • B22F1/054—Nanosized particles
    • B22F1/0551—Flake form nanoparticles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/05—Metallic powder characterised by the size or surface area of the particles
    • B22F1/054—Nanosized particles
    • B22F1/056—Submicron particles having a size above 100 nm up to 300 nm
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/18—Non-metallic particles coated with metal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2301/00—Metallic composition of the powder or its coating
    • B22F2301/25—Noble metals, i.e. Ag Au, Ir, Os, Pd, Pt, Rh, Ru
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y15/00—Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures

Definitions

  • the present invention relates to a silver nanoparticle composite, a silver nanoparticle composite suspension using the same, a composition for forming a ⁇ -ray sensitive sensor, a ⁇ -ray sensitive sensor, and a method for producing the silver nanoparticle composite.
  • Metal nanoparticles have various properties not found in bulk. For example, since gold and silver nanoparticles develop various colors by plasmon absorption, application as pigments and color materials for biosensors is being studied.
  • Non-patent Document 1 describes a thick material composed of a protective agent such as a comb-shaped block polymer, a reducing agent, and metal nanoparticles. In the paste, there is described a method of controlling the color change by adjusting the metal core / shell particles to control the particle diameter of the metal nanoparticles.
  • TECHNO-COSMOS Nippon Paint Co., Ltd., 2002 Feb., Vol.
  • Non-Patent Document 2 describes a pigment paste composed of metal nanoparticles, an aliphatic tertiary amine and a comb block. A method for stabilizing the color of pigments by controlling the aggregation of metal nanoparticles with a copolymer is described.
  • silver nanoparticles are known to be colored depending on the shape of the particles, and when the shape is spherical and has a diameter of about 10 nm, it is colored yellow, In the case of a flat plate typified by a triangle, the plasmon absorption changes depending on the length of the side, so the color changes from blue to red. Therefore, it has been studied to adjust the hue and saturation depending on the particle shape by controlling the particle shape.
  • JP 2008-106315 A manufactures nanoparticles containing triangular tabular silver nanoparticles by irradiating a reducing aqueous solution containing a dispersant and silver nitrate with ultrasonic waves. A method is described.
  • Patent Document 2 discloses absorption in the wavelength range of 390 to 1100 nm by precipitating silver nitrate on particles such as alumina in an aqueous solution containing a dispersant and a reducing agent. A method for producing spectrally controlled silver nanoparticles is described.
  • Patent Document 3 2007/058173 (Patent Document 3) is fixed on an ITO substrate by bringing a metal solution containing a polymer into contact with a nuclide adsorbed on the surface of the ITO substrate to grow the nuclide. A method for manufacturing a flat metal plate is described. Also, in Japanese translations of PCT publication No. 2011-502212 (Patent Document 4), a metal crystal nucleus is deposited on the surface of a metal single crystal substrate in a reaction furnace, and is grown on the surface, thereby being fixed on the metal single crystal substrate. A method for producing a flat metal plate is described.
  • JP 2008-106315 A JP 2009-221140 A International Publication No. 2007/058173 Special table 2011-502212 gazette
  • Triangular tabular silver nanoparticles have a red to blue color depending on their shape, but this shape is very unstable and tends to change to a spherical shape or the corners of the triangle may be lost, resulting in a small diameter. For this reason, as the diameter decreases with time, the color of the particles changes from blue to red to yellow.
  • the present invention has been made in view of the above-described problems of the prior art, and the content ratio of the triangular tabular silver nanoparticles is high, and the shape change of the triangular tabular silver nanoparticles is sufficiently suppressed even in the presence of halogen. It is an object of the present invention to provide a silver nanoparticle composite, a silver nanoparticle composite suspension, and a method for producing a silver nanoparticle composite.
  • the present inventor has obtained specific triangular tabular silver nanoparticles having a specific zeta potential at a pH of 5 to 7 and having at least one plane.
  • the content ratio of the triangular tabular silver nanoparticles is high, and the shape change of the triangular tabular silver nanoparticles is suppressed even in the presence of halogen. It has been found that a silver nanoparticle composite can be obtained in which is stably maintained.
  • the present inventor has found that the silver nanoparticle composite has sensitivity to ⁇ rays despite being stable (insensitive) to ultraviolet rays, and is irradiated with ⁇ rays. It is possible to obtain a composition for forming a ⁇ -ray sensitive sensor and a ⁇ -ray sensitive sensor by utilizing the sensitivity of such a silver nanoparticle composite to ⁇ rays by finding that the color of silver nanoparticles changes. As a result, the present invention has been completed.
  • the silver nanoparticle composite of the present invention is A plurality of triangular tabular silver nanoparticles having a main plane shape of a triangle or a substantially triangular shape, an initial average longest diameter of the main plane of 20 to 120 nm, and an initial average thickness of 5 nm or more and less than 20 nm are tabular. It is a silver nanoparticle composite formed by adsorbing on the plane of metal oxide particles, The tabular metal oxide particles are made of a metal oxide having a positive zeta potential at a pH of 5 to 7, and have an average of 16.7 to 500 times the initial average longest diameter of the triangular tabular silver nanoparticles as the plane.
  • the main plane has a longest diameter of 20 to 120 nm and a thickness of It is a triangular tabular silver nanoparticle that maintains a shape that satisfies the condition of 5 nm or more and less than 20 nm.
  • the aspect ratio (average diameter / thickness of the plane) of the plate-like metal oxide particles is preferably 10 to 100.
  • the plate-like metal oxide particles are preferably composed of at least one selected from the group consisting of ⁇ -alumina, ⁇ -alumina, titania and zinc oxide. .
  • the occupation area ratio of the triangular tabular silver nanoparticles adsorbed on the plane is 1 to 100% on the plane of the tabular metal oxide particles.
  • the mass ratio of the triangular tabular silver nanoparticles to the tabular metal oxide particles is from 1: 100 to 30: 100 is preferable.
  • the silver nanoparticle composite of the present invention is preferably used as a ⁇ -ray sensitive material that discolors and fades when irradiated with ⁇ -rays.
  • the silver nanoparticle composite suspension of the present invention is characterized in that the silver nanoparticle composite of the present invention is suspended in an aqueous solution.
  • the silver nanoparticle composite suspension of the present invention preferably has a pH equal to or higher than the isoelectric point of the plate-like metal oxide particles.
  • the ⁇ -ray sensitive sensor forming composition of the present invention is a ⁇ -ray sensitive sensor forming composition containing water and a ⁇ -ray sensitive material, and has a pH of 6 or more and less than 9.7,
  • the silver nanoparticle composite of the present invention is used as a sensitive material, and the ⁇ -ray sensitive sensor of the present invention is formed by the composition for forming a ⁇ -ray sensitive sensor.
  • the method for producing the silver nanoparticle composite of the present invention A plurality of triangular tabular silver nanoparticles having a main plane shape of a triangle or a substantially triangular shape, an initial average longest diameter of the main plane of 20 to 120 nm, and an initial average thickness of 5 nm or more and less than 20 nm; A plate-like metal oxide comprising a metal oxide having a positive zeta potential at pH 5 to 7 and having a plane having an average diameter of 16.7 to 500 times the initial average longest diameter of the triangular tabular silver nanoparticles as a plane.
  • the triangular tabular silver nanoparticles are adsorbed on the plane of the tabular metal oxide particles to obtain the silver nanoparticle composite of the present invention.
  • the mixing ratio of the triangular tabular silver nanoparticles and the tabular metal oxide particles mass of triangular tabular silver nanoparticles: tabular metal oxide
  • the mass of the particles is preferably from 1: 100 to 30: 100.
  • the present inventor presumes as follows. That is, in the present invention, the triangular or tabular silver nanoparticles of the triangular tabular silver nanoparticles or the specific tabular metal oxide particles according to the present invention are allowed to coexist in water having a pH of 5 to 7. The substantially triangular plane and the plane of the flat metal oxide particles are adsorbed by the adsorption energy. At this time, a surface dipole layer is formed by water molecules at the interface between the triangular tabular silver nanoparticles and the tabular metal oxide particles to generate an energy barrier, and silver on the surface of the triangular tabular silver nanoparticles is formed.
  • the shape change of the triangular tabular silver nanoparticles can be suppressed even in the presence of halogen.
  • the present inventors infer that the color that is derived from the shape at the time of adsorption of the nanoparticles can be stably maintained over time.
  • the silver nanoparticle composite of the present invention can suppress the shape change of the triangular tabular silver nanoparticles as described above, and is stable against ultraviolet rays despite being stable to ultraviolet rays. Since it has sensitivity, it is possible to obtain a composition for forming a ⁇ -ray sensitive sensor and a ⁇ -ray sensitive sensor by utilizing the sensitivity of the silver nanoparticle composite to ⁇ rays. The present inventors speculate. In addition, the sensitivity to the ⁇ -ray is because the triangular tabular silver nanoparticles are oxidized and changed in shape by radical species generated by the decomposition of water contained in the dispersion medium when irradiated with ⁇ -rays. The present inventor infers that it will be exhibited in the above.
  • the silver nanoparticle composite by using the silver nanoparticle composite, it is possible to provide a composition for forming a ⁇ -ray sensitive sensor and a ⁇ -ray sensitive sensor that are sufficiently stable to ultraviolet rays.
  • FIG. 3 is a graph showing the absorbance of silver nanoparticles 1 to 3 obtained in the preparation of silver nanoparticles.
  • 2 is a scanning electron micrograph at a magnification of 100,000 times immediately after adsorption of the silver nanoparticle composite obtained in Example 1.
  • FIG. 2 is a scanning electron micrograph at a magnification of 18,000 times immediately after adsorption of the silver nanoparticle composite obtained in Example 1.
  • FIG. 4 is a scanning electron micrograph at a magnification of 100,000 times immediately after adsorption of the silver nanoparticle composite obtained in Comparative Example 2.
  • FIG. 4 is a scanning electron micrograph at a magnification of 15,000 times immediately after adsorption of the silver nanoparticle composite obtained in Comparative Example 2.
  • FIG. 4 is a scanning electron micrograph at a magnification of 100,000 times immediately after adsorption of the silver nanoparticle composite obtained in Comparative Example 3.
  • FIG. 4 is a scanning electron micrograph at a magnification of 23,000 times immediately after adsorption of the silver nanoparticle composite obtained in Comparative Example 3.
  • FIG. 2 is a transmission electron micrograph from the plane tangential direction of the metal oxide particles of the silver nanoparticle composite obtained in Example 1.
  • FIG. 2 is an enlarged photograph of a transmission electron micrograph from the plane tangential direction of the metal oxide particles of the silver nanoparticle composite obtained in Example 1.
  • FIG. 6 is a graph showing the relationship between the value of x in the CIE color system and the elapsed time from the start of measurement in Example 1 and Comparative Examples 2 to 3.
  • FIG. 2 is a scanning electron micrograph at a magnification of 100,000 times after one week from the adsorption of the silver nanoparticle composite obtained in Example 1.
  • FIG. 2 is a scanning electron micrograph at a magnification of 27,000 after one week from the adsorption of the silver nanoparticle composite obtained in Example 1.
  • FIG. 4 is a scanning electron micrograph at a magnification of 100,000 times after one week from the adsorption of the silver nanoparticle composite obtained in Comparative Example 4.
  • FIG. 4 is a scanning electron micrograph at a magnification of 37,000 after one week from the adsorption of the silver nanoparticle composite obtained in Comparative Example 4.
  • 6 is a graph showing the relationship between the value of x in the CIE color system and the elapsed time from the start of measurement in Examples 2 to 5.
  • 6 is a graph showing the relationship between fading time and storage time in Examples 2 to 5.
  • 3 is a photograph showing a halftone image in which the state immediately after adsorption of the silver nanoparticle composite obtained in Examples 1 and 7 to 10 is displayed on a display.
  • 3 is a photograph showing a halftone image in which a state after 456 hours has elapsed from the adsorption of the silver nanoparticle composite obtained in Examples 1 and 7 to 10 is displayed on a display.
  • 6 is a photograph showing a halftone image in which the composition obtained in Examples 11 to 13 is displayed on a display in a state before ⁇ -ray irradiation.
  • 2 is a photograph showing a halftone image in which a state obtained after irradiating 300 Gy of ⁇ rays to the compositions obtained in Examples 11 to 13 is displayed on a display.
  • 2 is a graph showing CIE chromaticity diagrams before and after irradiating 300 Gy of ⁇ rays to the compositions obtained in Examples 11 to 13.
  • 6 is a photograph showing a halftone image in which the composition obtained in Examples 14 to 16 and Comparative Example 7 is displayed on a display in a state before ⁇ -ray irradiation.
  • 6 is a photograph showing a halftone image in which the composition obtained in Examples 14 to 16 and Comparative Example 7 is irradiated with 3000 Gy of ⁇ -rays and displayed on the display. 6 is a graph showing CIE chromaticity diagrams before and after irradiating 3000 Gy of ⁇ rays to the compositions obtained in Examples 14 to 16 and Comparative Example 7. FIG.
  • the silver nanoparticle composite of the present invention is formed by adsorbing a plurality of triangular tabular silver nanoparticles on the flat surface of the tabular metal oxide particles.
  • the shape of the main plane is triangular or substantially triangular.
  • the main plane of the triangular tabular silver nanoparticles refers to a flat surface having the largest area and an opposing flat surface among the outer surfaces of one particle.
  • the substantially triangular shape in the present invention refers to a shape in which three corners of a triangle are missing, and the missing rate of each corner is 16.7% or less.
  • the substantially triangular area means the area of the projection on the outer surface parallel to the plane of the approximate triangle
  • the ideal triangle area means that the straight portion of the approximate triangle is extended.
  • Indicates the area of the triangle to be formed, and the approximate triangular area with only the target angle missing is the area of the shape in which only the target corner for which the defect rate is determined in the ideal triangle is the part of the approximate triangle.
  • the triangular tabular silver nanoparticles according to the present invention are those having the longest diameter of the main plane in the range of 20 to 120 nm.
  • the longest diameter of the main plane refers to the longest diameter in the main plane.
  • the main plane has a triangular shape, it indicates the length of the longest side.
  • the plasmon absorption wavelength is out of the visible range, so that the silver nanoparticles are not colored.
  • the longest diameter of the main plane tends to decrease with time, but the plurality of triangular tabular silver nanoparticles according to the present invention have an initial average longest diameter of the main plane of 20 to 120 nm. It is necessary.
  • the initial average longest diameter of the main plane refers to the average value of the initial longest diameter in the plurality of triangular tabular silver nanoparticles, and the initial longest diameter refers to the triangular tabular silver nanoparticles in the present invention.
  • the longest diameter of the main plane immediately after adsorbing on the flat surface of the flat metal oxide particles (preferably 0 to 120 minutes after the adsorption). When the initial average longest diameter is less than the lower limit and exceeds the upper limit, the plasmon absorption wavelength is out of the visible range, so the silver nanoparticles do not color.
  • the triangular tabular silver nanoparticles according to the present invention are those having a thickness in the range of 5 nm or more and less than 20 nm.
  • the thickness refers to an average distance between the main planes.
  • the thickness is less than the lower limit, the shape of the triangular tabular silver nanoparticles cannot be maintained because the plate shape becomes unstable.
  • the thickness exceeds the upper limit, the shape of the particles is a flat plate. Therefore, the color derived from the shape of the triangular tabular silver nanoparticles according to the present invention is not exhibited.
  • the plurality of triangular tabular silver nanoparticles according to the present invention must have an initial average thickness of 5 nm or more and less than 20 nm.
  • the initial average thickness refers to an average value of initial thicknesses of the plurality of triangular tabular silver nanoparticles, and the initial thickness refers to the tabular metal oxidation of the triangular tabular silver nanoparticles according to the present invention. This refers to the thickness of the triangular tabular silver nanoparticles immediately after adsorbing on the plane of the product particles (preferably 0 to 120 minutes after the adsorption).
  • the initial average thickness is less than the lower limit, the shape of the triangular tabular silver nanoparticles cannot be maintained because the tabular shape becomes unstable. Since it is no longer a flat plate, it does not exhibit a color derived from the shape of the triangular tabular silver nanoparticles according to the present invention.
  • the longest diameter of the main plane of the triangular tabular silver nanoparticles according to the present invention, the initial average longest diameter, the thickness, and the initial average thickness of the main plane are all determined by a scanning electron microscope (SEM) or It can obtain
  • SEM scanning electron microscope
  • TEM transmission electron microscope
  • the plurality of triangular tabular silver nanoparticles according to the present invention preferably have an initial average aspect ratio (initial average longest diameter / initial average thickness) of 4 to 24.
  • the initial average aspect ratio is less than the lower limit, the shape of the grains is not a flat plate, and therefore tends not to exhibit a color derived from the shape of the triangular tabular silver nanoparticles according to the present invention, while the upper limit is In the case of exceeding, since the plate shape becomes unstable, the shape of the triangular tabular silver nanoparticles cannot be maintained, and the color derived from the shape of the triangular tabular silver nanoparticles according to the present invention tends not to be exhibited. .
  • the initial average area of the main plane is preferably 173 to 6236 nm 2 .
  • the initial average area of the main plane refers to an average value of the initial area of the main plane in the plurality of triangular tabular silver nanoparticles, and the initial area of the main plane refers to the triangular tabular silver nanoparticles.
  • the projected area of the outer surface parallel to the main plane immediately after adsorbing on the plane of the flat metal oxide particles according to the present invention preferably 0 to 120 minutes after the adsorption). (SEM) or a transmission electron microscope (TEM).
  • the tabular metal oxide particles according to the present invention have a plane having an average diameter of 16.7 to 500 times the initial average longest diameter of the plurality of triangular tabular silver nanoparticles.
  • the plane means a surface having a height difference between the lowest point of the concave portion on the surface and the top of the convex portion (height difference of the unevenness) of 1.3 nm or less. It can be measured by a transmission electron microscope (TEM).
  • TEM transmission electron microscope
  • the average diameter of the flat surface of the flat metal oxide particles means a diameter of a circle having an area equal to the average projected area of the flat surface of the flat metal oxide particles. It can be determined by measuring with an electron microscope (SEM) or a transmission electron microscope (TEM).
  • SEM electron microscope
  • TEM transmission electron microscope
  • the flat metal oxide particles according to the present invention need only have at least one of the planes, and even when the shape of the whole particle is a rectangular parallelepiped that can be regarded as a substantially flat plate,
  • the aspect ratio (average diameter of the plane) / Average thickness) is preferably 10 to 100.
  • the aspect ratio is less than the lower limit, the proportion of triangular tabular silver nanoparticles that contribute to effective absorption tends to be low.
  • the adsorbed all triangular tabular 5/6 of the silver nanoparticles will not contribute to effective absorption.
  • the flat metal oxide particles tend to be damaged.
  • the thickness of the flat metal oxide particles according to the present invention can be determined by measuring with a transmission electron microscope (TEM).
  • the flat metal oxide particles according to the present invention are made of a metal oxide having a positive zeta potential at pH 5-7.
  • the zeta potential is preferably +10 mV or more at 300 K and pH 5 to 7 and more preferably +25.8 mV or more from the viewpoint that adsorption tends to be disturbed by thermal energy.
  • Examples of such metal oxides having a zeta potential include ⁇ -alumina, ⁇ -alumina, titania, and zinc oxide. One of these may be used alone, or two or more may be used in combination. Good.
  • the plate-like metal oxide particles according to the present invention are composed of ⁇ -alumina from the viewpoint that the isoelectric point is pH 9 and tends to have a sufficiently high positive zeta potential at pH 7. More preferably.
  • the silver nanoparticle composite of the present invention is formed by adsorbing the plurality of triangular tabular silver nanoparticles on the plane of the tabular metal oxide particles, and the tabular metal oxide particles, A plurality of silver nanoparticles adsorbed on the plane.
  • the silver nanoparticles are particles made of silver and having a particle diameter of about 1 to 150 nm, and may be spherical particles or tabular particles.
  • the triangular tabular silver nanoparticles according to the present invention are included in the silver nanoparticles.
  • the triangular tabular silver nanoparticle is a triangular plate such as a sphere. There is a tendency to change to silver nanoparticles of a non-shaped shape.
  • the silver nanoparticle composite of the present invention 75% or more of silver nanoparticles out of the total number of the plurality of silver nanoparticles are in the shape of the main plane on the plane of the flat metal oxide particles.
  • the proportion of triangular tabular silver nanoparticles maintaining the shape in the total number of the silver nanoparticles may be any 30 adsorbed on the plane by a scanning electron microscope (SEM).
  • SEM scanning electron microscope
  • the proportion of triangular tabular silver nanoparticles maintaining the shape to the number of all silver nanoparticles measured can be calculated.
  • the proportion of triangular tabular silver nanoparticles maintaining the shape is the total number of the plurality of silver nanoparticles, It is preferably 77% or more.
  • the silver nanoparticle composite of the present invention contains a large amount of triangular tabular silver nanoparticles whose shape is maintained in this way, it is stably exhibited by plasmon absorption derived from the triangular tabular shape. Can be color.
  • the plasmon absorption peak wavelength is preferably in the range of 550 to 650 nm.
  • the occupation area ratio of the triangular tabular silver nanoparticles adsorbed on the plane is 1 to 100% on the plane of the tabular metal oxide particles. It is preferably 10 to 100%, more preferably 10 to 20%.
  • the occupied area ratio is less than the lower limit, the color exhibited by the triangular tabular silver nanoparticles tends to be thin, whereas when the upper limit is exceeded, the absorbance is raised in the visible range. The color exhibited by the triangular tabular silver nanoparticles tends to be dark or economically disadvantageous.
  • the occupied area ratio in the present invention refers to a flat metal oxide particle plane observed with a scanning electron microscope (SEM), and within an observation field (magnification 100,000 times, 0.4 ⁇ 0.4 ⁇ m region). This is a value obtained by measuring the occupation area ratio of the triangular tabular silver nanoparticles in FIG.
  • the mass ratio of the triangular tabular silver nanoparticles to the tabular metal oxide particles Is preferably 1: 100 to 30: 100, more preferably 1.5: 100 to 30: 100, and even more preferably 5: 100 to 10: 100.
  • the ratio of the triangular tabular silver nanoparticles to the tabular metal oxide particles is less than the lower limit, the shape of the triangular tabular silver nanoparticles tends to change in the silver nanoparticle composite, On the other hand, even if the triangular tabular silver nanoparticles are contained beyond the upper limit, the effect of suppressing the shape change of the triangular tabular silver nanoparticles is not further improved and tends to be economically disadvantageous.
  • the silver nanoparticle composite suspension of the present invention is characterized in that the silver nanoparticle composite of the present invention is suspended in an aqueous solution.
  • the shape change of the triangular tabular silver nanoparticles is sufficiently suppressed, the color change is suppressed even when stored for a long period of time. Even in the presence, the shape of triangular tabular silver nanoparticles is stably maintained.
  • the solvent for the aqueous solution examples include water subjected to purification such as ion exchange, distillation, and filtration.
  • the concentration of the silver nanoparticle composite is preferably 3 to 28 mg / ml, more preferably 7 to 14 mg / ml.
  • the concentration is less than the lower limit, the shape of the triangular tabular silver nanoparticles tends to change and the color tends to change, and on the other hand, the silver nanoparticle composite may be contained exceeding the upper limit.
  • the effect of suppressing the shape change of the triangular tabular silver nanoparticles does not improve any more, and tends to be economically disadvantageous.
  • the pH of the aqueous solution is preferably 5 or more, from the viewpoint that the silver nanoparticle composite is stabilized and the change in the shape of the triangular tabular silver nanoparticles is further suppressed by the negative potential, the plate shape
  • the isoelectric point of the metal oxide particles is preferably higher than the isoelectric point.
  • the pH is preferably 9 or higher, and more preferably 10 or higher. preferable.
  • the plate-like metal oxide particles are ⁇ -alumina
  • the pH is preferably 8 or more, and when it is titania, the pH is preferably 7 or more, and when it is zinc oxide.
  • the pH is preferably 10 or more.
  • a pH adjuster a pigment, a polymer compound, a surfactant, and other metal nanoparticles may be used as long as the effects of the present invention are not impaired. Further, it may further contain semiconductor nanoparticles, other metal oxide particles, protein particles and the like.
  • the silver nanoparticle composite of the present invention sufficiently suppresses the shape change of the triangular tabular silver nanoparticles even in the presence of halogen, and is stable to ultraviolet rays.
  • the present inventor has said that the silver nanoparticle composite has sensitivity to ⁇ rays, and when the ⁇ rays are irradiated to the silver nanoparticle composite, the color of the triangular tabular silver nanoparticles exhibits a long wavelength. It was found that the color changed or faded to the side. Therefore, the silver nanoparticle composite of the present invention can be used as a ⁇ -ray sensitive material that discolors and fades when irradiated with ⁇ -rays.
  • the absorbed dose of the ⁇ rays is preferably 30 Gy or more, and more preferably 300 Gy or more.
  • Examples of such a gamma ray source include cobalt 60 and cesium 137.
  • the composition for forming a gamma ray sensitive sensor and the gamma ray sensitive sensor of the present invention utilize the sensitivity to the gamma rays of the silver nanoparticle composite of the present invention, and the composition for forming a gamma ray sensitive sensor.
  • the pH needs to be 6 or more and less than 9.7.
  • the pH is less than the lower limit, the shape of the triangular tabular silver nanoparticles tends to change.
  • the pH exceeds the upper limit no discoloration occurs even when ⁇ rays are irradiated. More specifically, such a pH is preferably 6 to 9.6, and more preferably 6 to 8 from the viewpoint that discoloration tends to occur with a smaller ⁇ dose. preferable.
  • the water include water subjected to purification such as ion exchange, distillation, and filtration.
  • the concentration of the silver nanoparticle composite is preferably 100 mg / ml or less, more preferably 1 to 10 mg / ml before discoloration. preferable. If the concentration before the color change of the nanoparticle composite is less than the lower limit, it tends to be difficult to visually check the color of the silver nanoparticle composite itself. It tends to be difficult to recognize visually.
  • composition for forming a ⁇ -ray sensitive sensor of the present invention includes a pH adjuster, a pigment, a polymer compound, a surfactant, and other metal nanoparticles as necessary, as long as the effects of the present invention are not impaired. Further, it may further contain semiconductor nanoparticles, other metal oxide particles, protein particles and the like.
  • the ⁇ -ray sensitive sensor of the present invention is formed of the ⁇ -ray sensitive sensor forming composition of the present invention.
  • a method for forming such a ⁇ -ray sensitive sensor and a form of the ⁇ -ray sensitive sensor it is preferable to use a method and a form in which the water remains, for example, the composition for forming the ⁇ -ray sensitive sensor is a polyethylene film or the like.
  • the method for producing a silver nanoparticle composite of the present invention the plurality of triangular tabular silver nanoparticles and the tabular metal oxide particles are allowed to coexist in water having a pH of 5 to 7, thereby The silver nanoparticle composite of the present invention is obtained by adsorbing the plurality of silver nanoparticles on the flat surface.
  • the shape of the main plane is triangular or substantially triangular, the initial average longest diameter of the main plane is 20 to 120 nm, and the initial average thickness is 5 nm or more and less than 20 nm, and the shape of the main plane, the initial average longest diameter of the main plane, and the initial average thickness are as described in the silver nanoparticle composite of the present invention. .
  • triangular tabular silver nanoparticles As such a plurality of triangular tabular silver nanoparticles, triangular tabular silver nanoparticles more suitable for the silver nanoparticle composite of the present invention can be obtained, and the silver nanoparticles of the present invention can be efficiently and reproducibly obtained.
  • a composite first, a plurality of silver nanoparticles are synthesized, and then obtained by adjusting the content ratio of the triangular tabular silver nanoparticles in the synthesized silver nanoparticles by centrifugation. It is preferable to use those obtained.
  • a known method can be appropriately employed.
  • a method of synthesizing silver nanoparticles by irradiating light to a silver compound dissolved in a reducing solution can be mentioned. It is done.
  • the reducing solution include an aqueous solution containing a solvent, a reducing agent, a protective agent, and, if necessary, a complexing agent.
  • the solvent examples include water, supercritical water, water-soluble organic solvents (methanol, ethanol, propanol, isopropanol, butanol, acetone, acetonitrile, etc.), a mixed solvent of water and the water-soluble organic solvent, dimethyl sulfoxide, and the like. Of these, it is preferable to use water.
  • the reducing agent examples include sodium borohydride (NaBH 4 ), ascorbic acid, hydroxylamine (NH 2 OH), hydrazine (N 2 H 4 ), polyol, radiation, etc. Among them, sodium borohydride is used. Is preferred.
  • Examples of the protective agent include bis (p-sulfonatophenyl) phenylphosphine dipotassium, polyvinylpyrrolidone and the like. Among them, bis (p-sulfonatophenyl) phenylphosphine dipotassium is preferably used.
  • Examples of the complexing agent include citric acid.
  • the silver compound examples include silver hydroxide, chloride, nitrate, sulfate, acetate, sulfite, and inorganic complex salt. Among these, nitrate is preferably used.
  • the concentration of such a silver compound in the reducing solution is preferably 0.1 to 1 mmol / L.
  • Examples of the light source for the light irradiation include white fluorescent lamps, orange fluorescent lamps, incandescent lamps, xenon light sources, and lasers. Among these, white fluorescent lamps, orange fluorescent lamps, incandescent lamps are particularly inexpensive. A lamp is preferred.
  • the light irradiation time is preferably 50 hours or more, and more preferably 72 to 96 hours.
  • the number of rotations is preferably 1200 to 1640 G, and the time is preferably 30 to 60 minutes.
  • the rotational speed is less than the lower limit, silver nanoparticles cannot be recovered from the solution.
  • the upper limit is exceeded, a large amount of silver nanoparticles other than triangular tabular silver nanoparticles are precipitated. Therefore, the content ratio of the triangular tabular silver nanoparticles in the collected silver nanoparticles tends to decrease.
  • the time is less than the lower limit, the silver nanoparticles tend not to be recovered from the solution.
  • even if the centrifugation exceeds the upper limit more triangular tabular silver nanoparticles are recovered. It cannot be done and tends to be economically disadvantageous.
  • a plurality of silver nanoparticles containing a plurality of triangular tabular silver nanoparticles according to the present invention can be obtained as the precipitate fraction after the centrifugation.
  • the silver nanoparticles thus obtained are obtained as a blue to purple suspension, and the absorbance when measured by adding 900 ⁇ l of pure water to 40 ⁇ l of this suspension is in the range of 400 to 750 nm. Preferably, it is within the range of 580 to 750 nm.
  • the plate-like metal oxide particles used in the production method of the present invention are made of a metal oxide having a positive zeta potential at a pH of 5 to 7, and the initial average longest diameter of the triangular plate-like silver nanoparticles is 16.7 to
  • the flat metal oxide particles having a plane having an average diameter of 500 times are necessary, and the zeta potential and the plane are as described in the silver nanoparticle composite of the present invention.
  • Such flat metal oxide particles can be obtained by a known method, for example, a method in which a metal compound is directly pyrolyzed, or a method in which oxygen or water vapor is reacted at high temperature with the vapor of the metal compound.
  • a metal compound is directly pyrolyzed
  • oxygen or water vapor is reacted at high temperature with the vapor of the metal compound.
  • the metal include aluminum, titanium, zinc, and the like. Among them, aluminum is preferable from the viewpoint that it has no photocatalytic property and does not tend to oxidize the adsorbed silver nanoparticles.
  • the metal compound include metal hydroxides, chlorides, nitrates, sulfates, acetates, sulfites, and inorganic complex salts. Conditions for the thermal decomposition and the reaction of oxygen or water vapor can be appropriately adjusted depending on the type of metal compound. Moreover, as a flat metal oxide particle used for the manufacturing method of this invention, you may use a commercially available thing suit
  • Examples of water used in the production method of the present invention include water that has been subjected to purification such as ion exchange, distillation, and filtration. Moreover, as said water, you may contain gas, such as a pH adjuster and oxygen, as needed.
  • the pH of the water needs to be in the range of 5-7. When the pH deviates from the above range, the shape of the triangular tabular silver nanoparticles changes or it becomes difficult to adsorb the triangular tabular silver nanoparticles to the tabular metal oxide particles.
  • the pH is more preferably 5 to 6 from the viewpoint that the surface of the tabular metal oxide particles tends to have a sufficient positive charge.
  • the method for allowing the plurality of triangular tabular silver nanoparticles and the tabular metal oxide particles to coexist in the water is not particularly limited, and for example, the plurality of triangular tabular silver nanoparticles and the tabular metal oxide Examples thereof include a method in which a suspension obtained by mixing product particles in water is stirred for 30 seconds to 1 minute.
  • the mixing ratio of the triangular tabular silver nanoparticles and the tabular metal oxide particles is 1: 100 to 30: 100. It is preferably 1.5: 100 to 30: 100, more preferably 5: 100 to 10: 100.
  • the ratio of the triangular tabular silver nanoparticles to the tabular metal oxide particles is less than the lower limit, the shape of the triangular tabular silver nanoparticles tends to change in the obtained silver nanoparticle composite.
  • the effect of suppressing the shape change of the triangular tabular silver nanoparticles in the obtained silver nanoparticle composite is not further improved, and is economical. Tend to be disadvantageous.
  • the concentration of the suspension is preferably such that the total content of the triangular tabular silver nanoparticles and the tabular metal oxide particles is 0.9 to 1.1 mg / ml, More preferably, the concentration is 0.9 to 1.0 mg / ml.
  • concentration is less than the lower limit, the adsorption amount of the silver nanoparticles tends to be insufficient.
  • the concentration exceeds the upper limit the efficiency of the adsorption reaction tends to decrease.
  • the silver nanoparticle composite of the present invention in which the plurality of triangular tabular silver nanoparticles are adsorbed on the flat surface of the tabular metal oxide particles in a suspension can be obtained.
  • the silver nanoparticle composite powder of the present invention can be recovered from the suspension by a method such as centrifugation, filtration, and drying.
  • the suspension can be used as it is or by separating, concentrating, etc. to obtain the silver nanoparticle composite suspension of the present invention, and by adjusting the pH as necessary,
  • the composition for forming a gamma ray sensitive sensor of the invention can be obtained.
  • the suspension is the silver nanoparticle composite suspension of the present invention
  • the silver nanoparticle composite is more stabilized and the change in the shape of the triangular tabular silver nanoparticles is further suppressed.
  • the production method of the present invention further includes a stabilization step of storing the triangular tabular silver nanoparticles on the plane of the tabular metal oxide particles and then storing them in a sealed container for 50 hours or more. Is preferred.
  • the present inventors can obtain a silver nanoparticle composite that is more stable and can further suppress the shape change of triangular tabular silver nanoparticles. Found.
  • the sealed container is not particularly limited, and examples thereof include a glass bottle with a lid and a plastic bottle with a lid.
  • the suspension in which the tabular metal oxide particles and the triangular tabular silver nanoparticles coexist are transferred and stored in the sealed container as they are,
  • the suspension may further contain a pH adjuster, a polymer compound, inorganic fine particles, protein particles, etc., and the solid recovered from the suspension by a method such as centrifugation, filtration, or drying is again put into water.
  • a suspended suspension may be used.
  • the water include purified water such as ion exchange, distillation, and filtration.
  • the initial pH (pH at the start of storage) of such a suspension is preferably 5 to 7, and more preferably 5 to 6.
  • the pH is less than the lower limit, the shape of the triangular tabular silver nanoparticles tends to change, whereas when the upper limit is exceeded, it means that there are many impurities, There exists a tendency for the effect which suppresses the shape change of a flat silver nanoparticle to fall.
  • the suspension containing the silver nanoparticle composite preferably has a dissolved oxygen concentration of 1 to 8 mg-O / L at a water temperature of 25 ° C.
  • the dissolved oxygen concentration is less than the lower limit, the amount of increase in pH associated with the oxidation of silver nanoparticles by dissolved oxygen tends to be insufficient and unstable, and on the other hand, oxygen is included exceeding the upper limit.
  • the dissolved oxygen concentration does not exceed the saturation concentration (8.11 mg-O / L at a water temperature of 25 ° C.).
  • the concentration of the silver nanoparticle composite in the suspension is preferably 3 to 28 mg / ml, and more preferably 7 to 14 mg / ml.
  • the concentration is less than the lower limit, the shape of the triangular tabular silver nanoparticles tends to change and the color tends to change, and on the other hand, the silver nanoparticle composite may be contained exceeding the upper limit.
  • the effect of suppressing the shape change of the triangular tabular silver nanoparticles does not improve any more, and tends to be economically disadvantageous.
  • the storage time is preferably 3 months or longer.
  • the storage time is preferably 50 hours to 1 month.
  • the storage environment is not particularly limited, but it is preferable to stand at a temperature of 4 to 30 ° C. from the viewpoint that water does not freeze.
  • the suspension after the stabilizing step can be directly used as the silver nanoparticle composite suspension of the present invention, and by adjusting the pH as necessary,
  • the composition for forming a ⁇ -ray sensitive sensor of the present invention can be obtained.
  • the silver nanoparticle composite of the present invention can be obtained by recovering from the suspension by a method such as centrifugation, filtration, and drying.
  • a measurement sample is prepared by adding 900 ⁇ l of pure water to 40 ⁇ l of each suspension obtained by the preparation of silver nanoparticles, and the absorbance of each measurement sample is measured with an absorptiometer (trade name: USB2000, manufacturer: Ocean Optics, measurement). (Wavelength: 200 to 1100 nm). Moreover, about the supernatant obtained by preparation of silver nanoparticle, this was made into the measurement sample as it was, and the light absorbency was measured like the above.
  • Corner loss rate (%) ⁇ (ideal triangle area ⁇ substantially triangular area where only the target corner is missing) / ideal triangle area ⁇ ⁇ 100
  • the number of each corner obtained in step 1 was 16.7% or less, and the number was measured as triangular tabular silver nanoparticles.
  • Chromaticity (x, y) was calculated from the measured reflection spectrum by the CIE color system, and the time until x became 0.34 was defined as the fading time (minutes). In addition, it shows that the color change of a silver nanoparticle composite is so small that a fading time is long, and the shape change of the triangular tabular silver nanoparticle in a silver nanoparticle composite is suppressed.
  • x change amount (x value in measurement 2 ⁇ x value in measurement 1) / left time.
  • Silver nanoparticles used in each example and comparative example were prepared by the following methods. First, 0.02 mmol of bis (p-sulfonatophenyl) phenylphosphine dipotassium was added and dissolved in 200 ml of an aqueous silver nitrate solution (silver nitrate: 0.1 mmol / L), and further an aqueous sodium borohydride solution (NaBH 4 : 50 mmol / L). 2 ml was added and stirred for 10 minutes. This solution was irradiated with a white fluorescent lamp for 72 hours in the atmosphere at room temperature (25 ° C.) to obtain a suspension of black-violet silver nanoparticles.
  • the obtained suspension was centrifuged at 1640 G for 60 minutes to obtain about 2 ml of a suspension (suspension 1) of bright blue silver nanoparticles and a supernatant (supernatant 1).
  • the obtained supernatant 1 was further centrifuged at 5010 G for 60 minutes to obtain a suspension of dark blue silver nanoparticles (suspension 2) and a black purple supernatant (supernatant 2).
  • Absorbance was measured for the resulting suspensions 1-2 and supernatant 2. The measurement results of absorbance are shown in FIG.
  • the absorbance of the silver nanoparticles (silver nanoparticles 1) in the suspension 1 was in the range of 580 to 750 nm, the peak was 600 nm, and a bright blue color was exhibited. Further, the absorbance of the silver nanoparticles (silver nanoparticles 2) in the suspension 2 was in the range of 500 to 700 nm, the peak was 560 nm, and a dark blue color was exhibited. Further, the absorbance of the silver nanoparticles (silver nanoparticles 3) in the supernatant 2 was in the range of 400 to 650 nm, the peak was 520 nm, and a purple color close to black was exhibited.
  • the content of silver nanoparticles in the suspensions 1 and 2 and the supernatant 2 is 30% by mass, 20% by mass, and 45% by mass, respectively, and the inclusion of triangular tabular silver nanoparticles in the silver nanoparticles 1 to 3
  • the amounts were 79% by mass, 76% by mass and 28% by mass, respectively.
  • Metal oxide particles 1 ⁇ -alumina (trade name: Seraph, manufacturer: Kinseimatic, plane average projected area: 3.14 ⁇ m 2 (plane average diameter: 2 ⁇ m), flat plate (aspect ratio: 50 (2 ⁇ m) / 40 nm), zeta potential at pH 5.6: 42 mV)
  • Metal oxide particles 2 ⁇ -alumina (trade name: ⁇ -alumina 1-2 ⁇ , manufacturer: Wako Pure Chemical Industries, Ltd., average projected area of plane: 0.785 ⁇ m 2 (average diameter of plane: 1 ⁇ m), spherical Zeta potential at pH 5.6: 42 mV).
  • Examples 2 to 5 First, in the same manner as in Example 1, a silver nanoparticle composite suspension containing a bright blue silver nanoparticle composite was obtained. Next, the obtained silver nanoparticle composite suspension is put in a glass bottle with a lid as it is, and the lid is closed. 50 hours (Example 2), 16 days (Example 3), 25 days (Example 4) and 35 Each day (Example 5) was stored at room temperature (25 ° C.) to obtain silver nanoparticle composite suspensions.
  • Example 6 A silver nanoparticle composite containing a bright blue silver nanoparticle composite in the same manner as in Example 1 except that the silver nanoparticles 1 and the metal oxide particles 1 were stirred while bubbling and supplying oxygen. A suspension was obtained.
  • Examples 7 to 10 The mass ratio of silver nanoparticles 1 to metal oxide 1 (the mass of silver nanoparticles 1: the mass of metal oxide 1) was 1.6: 100 (Example 7) and 3.2: 100 (Example 8), respectively. ), 6.4: 100 (Example 9), 26.5: 100 (Example 10), and the same manner as in Example 1 except that the silver nanoparticle containing a bright blue silver nanoparticle composite is contained. Each of the particle composite suspensions was obtained.
  • Example 2 In the same manner as in Example 1 except that the suspension 2 containing silver nanoparticles 2 (silver nanoparticles 2: 2 mg) was used instead of the suspension 1 containing silver nanoparticles 1, a dark blue A silver nanoparticle composite suspension containing the silver nanoparticle composite was obtained.
  • Example 3 It replaced with the suspension liquid 1 containing the silver nanoparticle 1 and carried out similarly to Example 1 except having used the suspension liquid (supernatant 2, silver nanoparticle 3: 4.9 mg) containing the silver nanoparticle 3.
  • a silver nanoparticle composite suspension containing a black purple silver nanoparticle composite was obtained.
  • Example 5 A silver nanoparticle composite suspension was obtained in the same manner as in Example 1 except that sodium hydroxide was added to the aqueous suspension of metal oxide particles 1 to adjust the pH to 13. 1 faded and became visually transparent.
  • Example 6 A silver nanoparticle composite suspension was obtained in the same manner as in Example 1 except that hydrochloric acid was added to the aqueous suspension of metal oxide particles 1 to adjust the pH to 4 or less. could not be adsorbed on the metal oxide particles 1, and the silver nanoparticles 1 had turned purple.
  • the silver nanoparticle composite suspensions or suspensions obtained in each Example and Comparative Example were measured for the silver nanoparticle composite and evaluated for the stability of the composite.
  • Example 1 and Comparative Examples 1 to 3 Using the obtained silver nanoparticle composite suspension, we measured the silver nanoparticle composite immediately after adsorption of silver nanoparticles and metal oxide particles, and evaluated the stability in the presence of halogen. .
  • the measurement results of the silver nanoparticle composites in Example 1 and Comparative Examples 2 to 3 are shown in Table 1, and scanning electron micrographs (SEM images) are shown in FIGS. 2A to 4B, respectively.
  • Transmission electron micrographs (TEM images) of the particle composite are shown in FIGS. 5A and 5B.
  • particles that appear white are silver nanoparticles
  • flat plates that appear gray are metal oxide particles.
  • the flat plate that appears large in the center is metal oxide particles
  • the particles adsorbed on the surface are silver nanoparticles.
  • the content ratio of the triangular tabular silver nanoparticles according to the present invention is sufficiently high in the silver nanoparticle composite of the present invention. It was confirmed. Furthermore, from the TEM images shown in FIGS. 5A and 5B, it was confirmed that the thickness of the tabular silver nanoparticles was in the range of 5-7 nm. Moreover, it was confirmed that there is a slight gap (Gap) of less than 1 nm between the metal oxide particles and the silver nanoparticles adsorbed on the surface.
  • the silver nanoparticle composite of the present invention can be obtained even after one week has passed since the silver nanoparticles and the metal oxide particles are adsorbed.
  • the longest diameter of the particles remains sufficiently long, the content ratio of the triangular tabular silver nanoparticles is maintained sufficiently high, and the silver nanoparticle composite of the present invention has a small change amount of x. It was confirmed that the shape change of the tabular silver nanoparticles was sufficiently suppressed.
  • the silver nanoparticle composite obtained in Comparative Example 4 has a longest diameter of about 17% shorter than one week after the silver nanoparticles and the metal oxide particles are adsorbed. The content ratio of the nanoparticles was low, and the amount of change in x was large, confirming that the shape change of the triangular tabular silver nanoparticles was not sufficiently suppressed.
  • Example 11 ⁇ Production of composition> (Example 11) To the silver nanoparticle composite suspension obtained in Example 1, 0.1 M phosphate buffer (mixed solution of sodium dihydrogen phosphate and sodium hydrogen phosphate) was added to adjust the pH to 5.8. A bright blue composition (silver nanoparticle composite concentration: 10 mg / ml) was obtained.
  • Example 12 Comparative Example 7
  • the pH of the composition was 6.9 (Example 12), 7.8 (Example 13), 6.6 (Example 14), 7.3 (Example 15), 7.9 (Example 16) in this order.
  • 9.7 Comparative Example 7
  • the composition was obtained in the same manner as in Example 11.
  • Example 14 Using cobalt 60 as the ⁇ -ray source and comparing the compositions obtained in Examples 11 to 13 with 300 Gy (1.17 MeV, 1.33 MeV) ⁇ -rays at a temperature of 25 degrees, Examples 14 to 16 were compared.
  • the composition obtained in Example 7 was irradiated with 3000 Gy (1.17 MeV, 1.33 MeV) of ⁇ rays to evaluate the sensitivity to ⁇ rays.
  • FIGS. 13 and 14 The photographs showing the states obtained before and after irradiating the composition obtained in Examples 11 to 13 with 300 Gy of ⁇ rays are shown in FIGS. 13 and 14, respectively, and obtained in Examples 14 to 16 and Comparative Example 7.
  • CIE chromaticity diagrams obtained by measuring color information in the same manner as in the evaluation of stability over time in the absence of halogen before and after the irradiation of ⁇ rays are shown in FIG. 15 (Examples 11 to 13, 300 Gy). )
  • FIG. 18 Examples 14 to 16, Comparative Example 7; 3000 Gy), respectively.
  • FIG. 15 Examples 11 to 13, 300 Gy.
  • the composition of the present invention changed its color from vivid blue to red when irradiated with ⁇ rays, whereas in Comparative Example 7, the color change occurred. Not confirmed.
  • the composition of the present invention was confirmed to be stable against ultraviolet rays without causing discoloration even when left in an environment exposed to natural light.
  • a silver nanoparticle composite in which the content ratio of triangular tabular silver nanoparticles is high and the shape change of triangular tabular silver nanoparticles is sufficiently suppressed even in the presence of halogen, It becomes possible to provide a silver nanoparticle composite suspension and a method for producing a silver nanoparticle composite. Therefore, the silver nanoparticle composite and the silver nanoparticle composite suspension of the present invention are very useful as coloring materials for pigments, biosensors and the like.
  • the silver nanoparticle composite by using the silver nanoparticle composite, it is possible to provide a composition for forming a ⁇ -ray sensitive sensor and a ⁇ -ray sensitive sensor that are sufficiently stable against ultraviolet rays.

Abstract

Provided is a silver nanoparticle composite which is obtained by adsorption of a plurality of triangular flat plate-shaped silver nanoparticles onto the planar face of flat plate-shaped metal oxide particles. The shape of the main planar face of the plurality of triangular flat plate-shaped silver nanoparticles is triangular or substantially triangular, the initial average longest diameter of the main planar face is 20 to 120 nm, and the initial average thickness is at least 5 nm but less than 20 nm. The flat plate-shaped metal oxide particles comprise a metal oxide of positive ζ potential at pH 5 to 7 and, as the planar face, have a planar face having an average diameter of 16.7 to 500 times the initial average longest diameter of the triangular flat plate-shaped silver nanoparticles. In the silver nanoparticle composite, at least 75% of the total number of silver nanoparticles that are adsorbed onto this planar face are silver nanoparticles of triangular flat plate shape and maintain a shape that satisfies the conditions of the main planar face shape thereof being triangular or substantially triangular, the longest diameter of this main planar face being 20 to 120 nm, and the thickness thereof being at least 5 nm but less than 20 nm.

Description

銀ナノ粒子複合体、それを用いた銀ナノ粒子複合体懸濁液、γ線感応センサ形成用組成物及びγ線感応センサ、並びに銀ナノ粒子複合体の製造方法Silver nanoparticle composite, silver nanoparticle composite suspension using the same, composition for forming γ-ray sensitive sensor, γ-ray sensitive sensor, and method for producing silver nanoparticle composite
　本発明は、銀ナノ粒子複合体、それを用いた銀ナノ粒子複合体懸濁液、γ線感応センサ形成用組成物及びγ線感応センサ、並びに銀ナノ粒子複合体の製造方法に関する。 The present invention relates to a silver nanoparticle composite, a silver nanoparticle composite suspension using the same, a composition for forming a γ-ray sensitive sensor, a γ-ray sensitive sensor, and a method for producing the silver nanoparticle composite.
　金属ナノ粒子はバルクには見られない様々な性質を有する。例えば、金や銀のナノ粒子はプラズモン吸収によって様々な色を発色するため、顔料やバイオセンサ用の色材としての応用が検討されている。例えば、「ＴＥＣＨＮＯ－ＣＯＳＭＯＳ、日本ペイント社、２００８　Ｍａｒ．、Ｖｏｌ．２１、３２－３８頁」（非特許文献１）には、櫛形ブロックポリマー等の保護剤、還元剤及び金属ナノ粒子からなる濃厚ペーストにおいて、金属のコア／シェル粒子を調整して金属ナノ粒子の粒子径を制御することにより、その色変化を制御する方法が記載されている。さらに、「ＴＥＣＨＮＯ－ＣＯＳＭＯＳ、日本ペイント社、２００２　Ｆｅｂ．、Ｖｏｌ．１５、２－７頁」（非特許文献２）には、金属ナノ粒子からなる顔料ペーストにおいて、脂肪族３級アミンと櫛形ブロックコポリマーとを用いて金属ナノ粒子の凝集を制御することにより、顔料の色を安定させる方法が記載されている。 Metal nanoparticles have various properties not found in bulk. For example, since gold and silver nanoparticles develop various colors by plasmon absorption, application as pigments and color materials for biosensors is being studied. For example, “TECHNO-COSMOS, Nippon Paint Co., Ltd., 2008 Mar., Vol. 21, pp. 32-38” (Non-patent Document 1) describes a thick material composed of a protective agent such as a comb-shaped block polymer, a reducing agent, and metal nanoparticles. In the paste, there is described a method of controlling the color change by adjusting the metal core / shell particles to control the particle diameter of the metal nanoparticles. Furthermore, “TECHNO-COSMOS, Nippon Paint Co., Ltd., 2002 Feb., Vol. 15, pages 2-7” (Non-Patent Document 2) describes a pigment paste composed of metal nanoparticles, an aliphatic tertiary amine and a comb block. A method for stabilizing the color of pigments by controlling the aggregation of metal nanoparticles with a copolymer is described.
　また、金属ナノ粒子の中でも、銀ナノ粒子は粒子の形状に依存して呈色することが知られており、その形状が球状で直径１０ｎｍ前後である場合には黄色に呈色し、他方、三角形に代表される平板状である場合にはその辺の長さによってプラズモン吸収が変化するため、青色～赤色に色が変化する。従って、このような粒子の形状を制御することにより、粒子の形状に依存した色相や彩度を調整することが検討されている。 Further, among metal nanoparticles, silver nanoparticles are known to be colored depending on the shape of the particles, and when the shape is spherical and has a diameter of about 10 nm, it is colored yellow, In the case of a flat plate typified by a triangle, the plasmon absorption changes depending on the length of the side, so the color changes from blue to red. Therefore, it has been studied to adjust the hue and saturation depending on the particle shape by controlling the particle shape.
　例えば、特開２００８－１０６３１５号公報（特許文献１）には、分散剤と硝酸銀とを含有する還元水溶液に超音波を照射することにより、三角形の平板状銀ナノ粒子を含むナノ粒子を製造する方法が記載されている。また、特開２００９－２２１１４０号公報（特許文献２）には、分散剤と還元剤とを含有する水溶液中において硝酸銀をアルミナ等の粒子上に析出させることにより、波長３９０～１１００ｎｍの範囲の吸収スペクトルに制御された銀ナノ粒子を製造する方法が記載されている。さらに、国際公開第２００７／０５８１７３号（特許文献３）には、ＩＴＯ基板表面に吸着させた核種にポリマーを含有する金属溶液を接触させて前記核種を成長せしめることにより、ＩＴＯ基板上に固定された平板状の金属プレートを製造する方法が記載されている。また、特表２０１１－５０２２１２号公報（特許文献４）には、反応炉において金属単結晶基板表面に金属の結晶核を析出させ、これを成長せしめることにより、金属単結晶基板上に固定された平板状の金属プレートを製造する方法が記載されている。 For example, JP 2008-106315 A (Patent Document 1) manufactures nanoparticles containing triangular tabular silver nanoparticles by irradiating a reducing aqueous solution containing a dispersant and silver nitrate with ultrasonic waves. A method is described. Japanese Patent Application Laid-Open No. 2009-221140 (Patent Document 2) discloses absorption in the wavelength range of 390 to 1100 nm by precipitating silver nitrate on particles such as alumina in an aqueous solution containing a dispersant and a reducing agent. A method for producing spectrally controlled silver nanoparticles is described. Furthermore, International Publication No. 2007/058173 (Patent Document 3) is fixed on an ITO substrate by bringing a metal solution containing a polymer into contact with a nuclide adsorbed on the surface of the ITO substrate to grow the nuclide. A method for manufacturing a flat metal plate is described. Also, in Japanese translations of PCT publication No. 2011-502212 (Patent Document 4), a metal crystal nucleus is deposited on the surface of a metal single crystal substrate in a reaction furnace, and is grown on the surface, thereby being fixed on the metal single crystal substrate. A method for producing a flat metal plate is described.
特開２００８－１０６３１５号公報JP 2008-106315 A 特開２００９－２２１１４０号公報JP 2009-221140 A 国際公開第２００７／０５８１７３号International Publication No. 2007/058173 特表２０１１－５０２２１２号公報Special table 2011-502212 gazette
　特許文献１～４に記載の方法によれば、平板状の銀ナノ粒子をある程度得ることは可能であるものの、これらの方法のように粒子を直接基板等の表面に析出させる方法では、結晶核の形成と結晶成長とを完全に分離できないため、球状の粒子と平板状の粒子とが混在してしまい、三角形の主平面を有する三角平板状銀ナノ粒子にのみ由来する色を安定して呈色せしめることは未だ困難であるということを本発明者は見出した。 According to the methods described in Patent Documents 1 to 4, it is possible to obtain tabular silver nanoparticles to some extent, but in the method of depositing particles directly on the surface of a substrate or the like like these methods, Formation and crystal growth cannot be completely separated, so that spherical particles and tabular grains are mixed, and a color derived only from triangular tabular silver nanoparticles having a triangular main plane is stably exhibited. The inventor has found that it is still difficult to color.
　また、三角平板状銀ナノ粒子はその形状に依存して赤色～青色を呈するが、この形状は非常に不安定で、球状に変化したり三角形の角が欠損して直径が小さくなったりしやすいため、時間経過によって直径が小さくなると共に粒子の呈する色は青色から赤～黄色へと変化してしまう。特に、ハロゲンを添加すると三角平板状銀ナノ粒子の形状は著しく変化しやすくなるため、特許文献１～４に記載の方法のように分散剤や保護剤により保護されていても、ハロゲンの添加によって銀ナノ粒子の形状が直ちに球状に変化し、粒子の呈する色が、例えば、青色から紫や黄色に変化してしまうという問題があることを本発明者は見出した。 Triangular tabular silver nanoparticles have a red to blue color depending on their shape, but this shape is very unstable and tends to change to a spherical shape or the corners of the triangle may be lost, resulting in a small diameter. For this reason, as the diameter decreases with time, the color of the particles changes from blue to red to yellow. In particular, since the shape of triangular tabular silver nanoparticles is remarkably changed when halogen is added, even if it is protected by a dispersant or a protective agent as in the methods described in Patent Documents 1 to 4, addition of halogen causes The present inventor has found that there is a problem that the shape of the silver nanoparticles immediately changes to a spherical shape and the color of the particles changes from blue to purple or yellow, for example.
　本発明は、上記従来技術の有する課題に鑑みてなされたものであり、三角平板状銀ナノ粒子の含有比率が高く、ハロゲンの存在下でも三角平板状銀ナノ粒子の形状変化が十分に抑制される銀ナノ粒子複合体、銀ナノ粒子複合体懸濁液及び銀ナノ粒子複合体の製造方法を提供することを目的とする。 The present invention has been made in view of the above-described problems of the prior art, and the content ratio of the triangular tabular silver nanoparticles is high, and the shape change of the triangular tabular silver nanoparticles is sufficiently suppressed even in the presence of halogen. It is an object of the present invention to provide a silver nanoparticle composite, a silver nanoparticle composite suspension, and a method for producing a silver nanoparticle composite.
　本発明者は、上記目的を達成すべく鋭意研究を重ねた結果、特定の三角平板状銀ナノ粒子を、ｐＨ５～７におけるゼータ電位が正であり、少なくとも１つの平面を有している特定の平板状金属酸化物粒子の前記平面上に吸着させることにより、三角平板状銀ナノ粒子の含有比率が高く、しかも、ハロゲンの存在下でも三角平板状銀ナノ粒子の形状変化が抑制され、その形状が安定に維持される銀ナノ粒子複合体が得られることを見出した。 As a result of intensive studies to achieve the above object, the present inventor has obtained specific triangular tabular silver nanoparticles having a specific zeta potential at a pH of 5 to 7 and having at least one plane. By adsorbing on the flat surface of the tabular metal oxide particles, the content ratio of the triangular tabular silver nanoparticles is high, and the shape change of the triangular tabular silver nanoparticles is suppressed even in the presence of halogen. It has been found that a silver nanoparticle composite can be obtained in which is stably maintained.
　さらに、本発明者は、前記銀ナノ粒子複合体は、紫外線に対して安定（不感応）であるにもかかわらず、γ線に対する感応性を有しており、γ線が照射されることにより銀ナノ粒子の呈する色が変化することを見出し、このような銀ナノ粒子複合体のγ線に対する感応性を利用してγ線感応センサ形成用組成物及びγ線感応センサを得ることが可能であることを見出し、本発明を完成するに至った。 Furthermore, the present inventor has found that the silver nanoparticle composite has sensitivity to γ rays despite being stable (insensitive) to ultraviolet rays, and is irradiated with γ rays. It is possible to obtain a composition for forming a γ-ray sensitive sensor and a γ-ray sensitive sensor by utilizing the sensitivity of such a silver nanoparticle composite to γ rays by finding that the color of silver nanoparticles changes. As a result, the present invention has been completed.
　すなわち、本発明の銀ナノ粒子複合体は、
　主平面の形状が三角形又は略三角形であり、前記主平面の初期平均最長径が２０～１２０ｎｍであり且つ初期平均厚さが５ｎｍ以上２０ｎｍ未満である複数の三角平板状銀ナノ粒子が、平板状金属酸化物粒子の平面上に吸着してなる銀ナノ粒子複合体であり、
　前記平板状金属酸化物粒子が、ｐＨ５～７におけるゼータ電位が正の金属酸化物からなり、且つ、前記平面として前記三角平板状銀ナノ粒子の初期平均最長径の１６．７～５００倍の平均直径を有する平面を有するものであり、
　前記平面上に吸着されている銀ナノ粒子の全個数のうちの７５％以上が、主平面の形状が三角形又は略三角形であり、前記主平面の最長径が２０～１２０ｎｍであり且つ厚さが５ｎｍ以上２０ｎｍ未満であるという条件を満たす形状を維持している三角平板状銀ナノ粒子であるものである。 That is, the silver nanoparticle composite of the present invention is
A plurality of triangular tabular silver nanoparticles having a main plane shape of a triangle or a substantially triangular shape, an initial average longest diameter of the main plane of 20 to 120 nm, and an initial average thickness of 5 nm or more and less than 20 nm are tabular. It is a silver nanoparticle composite formed by adsorbing on the plane of metal oxide particles,
The tabular metal oxide particles are made of a metal oxide having a positive zeta potential at a pH of 5 to 7, and have an average of 16.7 to 500 times the initial average longest diameter of the triangular tabular silver nanoparticles as the plane. Having a plane with a diameter,
More than 75% of the total number of silver nanoparticles adsorbed on the plane has a main plane shape of a triangle or a substantially triangle, the main plane has a longest diameter of 20 to 120 nm and a thickness of It is a triangular tabular silver nanoparticle that maintains a shape that satisfies the condition of 5 nm or more and less than 20 nm.
　本発明の銀ナノ粒子複合体としては、平板状金属酸化物粒子のアスペクト比（平面の平均直径／厚さ）が１０～１００であることが好ましい。また、本発明の銀ナノ粒子複合体としては、前記平板状金属酸化物粒子がα－アルミナ、γ－アルミナ、チタニア及び酸化亜鉛からなる群から選択される少なくともいずれか１種からなることが好ましい。 In the silver nanoparticle composite of the present invention, the aspect ratio (average diameter / thickness of the plane) of the plate-like metal oxide particles is preferably 10 to 100. In the silver nanoparticle composite of the present invention, the plate-like metal oxide particles are preferably composed of at least one selected from the group consisting of α-alumina, γ-alumina, titania and zinc oxide. .
　さらに、本発明の銀ナノ粒子複合体としては、前記平板状金属酸化物粒子の平面上において、前記平面上に吸着されている前記三角平板状銀ナノ粒子の占有面積率が１～１００％であることが好ましく、前記三角平板状銀ナノ粒子と前記平板状金属酸化物粒子との質量比（三角平板状銀ナノ粒子の質量：平板状金属酸化物粒子の質量）が１：１００～３０：１００であることが好ましい。 Furthermore, in the silver nanoparticle composite of the present invention, the occupation area ratio of the triangular tabular silver nanoparticles adsorbed on the plane is 1 to 100% on the plane of the tabular metal oxide particles. Preferably, the mass ratio of the triangular tabular silver nanoparticles to the tabular metal oxide particles (the mass of the triangular tabular silver nanoparticles: the mass of the tabular metal oxide particles) is from 1: 100 to 30: 100 is preferable.
　また、本発明の銀ナノ粒子複合体としては、γ線が照射されることにより変退色するγ線感応材料として用いられることが好ましい。 Also, the silver nanoparticle composite of the present invention is preferably used as a γ-ray sensitive material that discolors and fades when irradiated with γ-rays.
　本発明の銀ナノ粒子複合体懸濁液は、上記本発明の銀ナノ粒子複合体が水溶液中に懸濁されていることを特徴とするものである。前記本発明の銀ナノ粒子複合体懸濁液としては、ｐＨが前記平板状金属酸化物粒子の等電点以上であることが好ましい。 The silver nanoparticle composite suspension of the present invention is characterized in that the silver nanoparticle composite of the present invention is suspended in an aqueous solution. The silver nanoparticle composite suspension of the present invention preferably has a pH equal to or higher than the isoelectric point of the plate-like metal oxide particles.
　また、本発明のγ線感応センサ形成用組成物は、水及びγ線感応材料を含有するγ線感応センサ形成用組成物であって、ｐＨが６以上９．７未満であり、前記γ線感応材料として前記本発明の銀ナノ粒子複合体を用いるものであり、本発明のγ線感応センサは、前記γ線感応センサ形成用組成物により形成されたものである。 The γ-ray sensitive sensor forming composition of the present invention is a γ-ray sensitive sensor forming composition containing water and a γ-ray sensitive material, and has a pH of 6 or more and less than 9.7, The silver nanoparticle composite of the present invention is used as a sensitive material, and the γ-ray sensitive sensor of the present invention is formed by the composition for forming a γ-ray sensitive sensor.
　また、本発明の銀ナノ粒子複合体の製造方法は、
　主平面の形状が三角形又は略三角形であり、前記主平面の初期平均最長径が２０～１２０ｎｍであり且つ初期平均厚さが５ｎｍ以上２０ｎｍ未満である複数の三角平板状銀ナノ粒子と、
　ｐＨ５～７におけるゼータ電位が正の金属酸化物からなり、且つ、平面として前記三角平板状銀ナノ粒子の初期平均最長径の１６．７～５００倍の平均直径を有する平面を有する平板状金属酸化物粒子とを、
　ｐＨ５～７の水中において共存せしめることにより、前記平板状金属酸化物粒子の平面上に前記三角平板状銀ナノ粒子を吸着せしめて前記本発明の銀ナノ粒子複合体を得るものである。 In addition, the method for producing the silver nanoparticle composite of the present invention,
A plurality of triangular tabular silver nanoparticles having a main plane shape of a triangle or a substantially triangular shape, an initial average longest diameter of the main plane of 20 to 120 nm, and an initial average thickness of 5 nm or more and less than 20 nm;
A plate-like metal oxide comprising a metal oxide having a positive zeta potential at pH 5 to 7 and having a plane having an average diameter of 16.7 to 500 times the initial average longest diameter of the triangular tabular silver nanoparticles as a plane. With the particles
By coexisting in water having a pH of 5 to 7, the triangular tabular silver nanoparticles are adsorbed on the plane of the tabular metal oxide particles to obtain the silver nanoparticle composite of the present invention.
　本発明の銀ナノ粒子複合体の製造方法としては、前記平板状金属酸化物粒子の平面上に前記三角平板状銀ナノ粒子を吸着せしめた後に、密封容器内において５０時間以上保存する安定化工程をさらに備えることが好ましい。また、本発明の銀ナノ粒子複合体の製造方法においては、前記三角平板状銀ナノ粒子と前記平板状金属酸化物粒子との配合比（三角平板状銀ナノ粒子の質量：平板状金属酸化物粒子の質量）が１：１００～３０：１００であることが好ましい。 As a method for producing the silver nanoparticle composite of the present invention, a stabilizing step of storing the triangular tabular silver nanoparticles on the plane of the tabular metal oxide particles and then storing them in a sealed container for 50 hours or more It is preferable to further comprise. In the method for producing a silver nanoparticle composite of the present invention, the mixing ratio of the triangular tabular silver nanoparticles and the tabular metal oxide particles (mass of triangular tabular silver nanoparticles: tabular metal oxide) The mass of the particles is preferably from 1: 100 to 30: 100.
　なお、本発明によって上記目的が達成されるようになる理由は必ずしも定かではないが、本発明者は以下のように推察する。すなわち、本発明においては、ｐＨ５～７の水中において本発明に係る特定の三角平板状銀ナノ粒子と特定の平板状金属酸化物粒子とを共存せしめることにより、三角平板状銀ナノ粒子の三角形又は略三角形の面と、平板状金属酸化物粒子の有する平面とが吸着エネルギーにより吸着する。このとき、前記三角平板状銀ナノ粒子と前記平板状金属酸化物粒子との界面においては水分子による表面ダイポール層が形成されてエネルギー障壁が生成し、前記三角平板状銀ナノ粒子の表面における銀のイオン化やハロゲンとの反応が抑制されるため、本発明の銀ナノ粒子複合体においては、ハロゲンの存在下においても三角平板状銀ナノ粒子の形状変化を抑制することができ、三角平板状銀ナノ粒子の吸着時の形状に由来して呈される色を時間が経過しても安定して維持することができると本発明者らは推察する。 It should be noted that the reason why the above object is achieved by the present invention is not necessarily clear, but the present inventor presumes as follows. That is, in the present invention, the triangular or tabular silver nanoparticles of the triangular tabular silver nanoparticles or the specific tabular metal oxide particles according to the present invention are allowed to coexist in water having a pH of 5 to 7. The substantially triangular plane and the plane of the flat metal oxide particles are adsorbed by the adsorption energy. At this time, a surface dipole layer is formed by water molecules at the interface between the triangular tabular silver nanoparticles and the tabular metal oxide particles to generate an energy barrier, and silver on the surface of the triangular tabular silver nanoparticles is formed. In the silver nanoparticle composite of the present invention, the shape change of the triangular tabular silver nanoparticles can be suppressed even in the presence of halogen. The present inventors infer that the color that is derived from the shape at the time of adsorption of the nanoparticles can be stably maintained over time.
　さらに、本発明の銀ナノ粒子複合体は、上記のように三角平板状銀ナノ粒子の形状変化を抑制することができ、紫外線に対して安定であるにもかかわらず、γ線に対しては感応性を有しているため、このような前記銀ナノ粒子複合体のγ線に対する感応性を利用することによりγ線感応センサ形成用組成物及びγ線感応センサを得ることが可能であると本発明者らは推察する。また、前記γ線に対する感応性は、γ線が照射されることにより分散媒に含有される水が分解されて生じたラジカル種により前記三角平板状銀ナノ粒子が酸化して形状が変化するために発揮されると本発明者は推察する。 Furthermore, the silver nanoparticle composite of the present invention can suppress the shape change of the triangular tabular silver nanoparticles as described above, and is stable against ultraviolet rays despite being stable to ultraviolet rays. Since it has sensitivity, it is possible to obtain a composition for forming a γ-ray sensitive sensor and a γ-ray sensitive sensor by utilizing the sensitivity of the silver nanoparticle composite to γ rays. The present inventors speculate. In addition, the sensitivity to the γ-ray is because the triangular tabular silver nanoparticles are oxidized and changed in shape by radical species generated by the decomposition of water contained in the dispersion medium when irradiated with γ-rays. The present inventor infers that it will be exhibited in the above.
　本発明によれば、三角平板状銀ナノ粒子の含有比率が高く、ハロゲンの存在下でも三角平板状銀ナノ粒子の形状変化が十分に抑制される銀ナノ粒子複合体、銀ナノ粒子複合体懸濁液及び銀ナノ粒子複合体の製造方法を提供することが可能となる。 According to the present invention, the silver nanoparticle composite, the silver nanoparticle composite suspension in which the content ratio of the triangular tabular silver nanoparticles is high and the shape change of the triangular tabular silver nanoparticles is sufficiently suppressed even in the presence of halogen. It becomes possible to provide a method for producing a suspension and a silver nanoparticle composite.
　さらに、本発明によれば、前記銀ナノ粒子複合体を用いることにより、紫外線に対して十分に安定であるγ線感応センサ形成用組成物及びγ線感応センサを提供することが可能となる。 Furthermore, according to the present invention, by using the silver nanoparticle composite, it is possible to provide a composition for forming a γ-ray sensitive sensor and a γ-ray sensitive sensor that are sufficiently stable to ultraviolet rays.
銀ナノ粒子の調製において得られた銀ナノ粒子１～３の吸光度を示すグラフである。3 is a graph showing the absorbance of silver nanoparticles 1 to 3 obtained in the preparation of silver nanoparticles. 実施例１で得られた銀ナノ粒子複合体の吸着直後の倍率１０万倍の走査型電子顕微鏡写真である。2 is a scanning electron micrograph at a magnification of 100,000 times immediately after adsorption of the silver nanoparticle composite obtained in Example 1. FIG. 実施例１で得られた銀ナノ粒子複合体の吸着直後の倍率１万８千倍の走査型電子顕微鏡写真である。2 is a scanning electron micrograph at a magnification of 18,000 times immediately after adsorption of the silver nanoparticle composite obtained in Example 1. FIG. 比較例２で得られた銀ナノ粒子複合体の吸着直後の倍率１０万倍の走査型電子顕微鏡写真である。4 is a scanning electron micrograph at a magnification of 100,000 times immediately after adsorption of the silver nanoparticle composite obtained in Comparative Example 2. FIG. 比較例２で得られた銀ナノ粒子複合体の吸着直後の倍率１万５千倍の走査型電子顕微鏡写真である。4 is a scanning electron micrograph at a magnification of 15,000 times immediately after adsorption of the silver nanoparticle composite obtained in Comparative Example 2. FIG. 比較例３で得られた銀ナノ粒子複合体の吸着直後の倍率１０万倍の走査型電子顕微鏡写真である。4 is a scanning electron micrograph at a magnification of 100,000 times immediately after adsorption of the silver nanoparticle composite obtained in Comparative Example 3. FIG. 比較例３で得られた銀ナノ粒子複合体の吸着直後の倍率２万３千倍の走査型電子顕微鏡写真である。4 is a scanning electron micrograph at a magnification of 23,000 times immediately after adsorption of the silver nanoparticle composite obtained in Comparative Example 3. FIG. 実施例１で得られた銀ナノ粒子複合体の金属酸化物粒子の平面接線方向からの透過型電子顕微鏡写真である。2 is a transmission electron micrograph from the plane tangential direction of the metal oxide particles of the silver nanoparticle composite obtained in Example 1. FIG. 実施例１で得られた銀ナノ粒子複合体の金属酸化物粒子の平面接線方向からの透過型電子顕微鏡写真の拡大写真である。2 is an enlarged photograph of a transmission electron micrograph from the plane tangential direction of the metal oxide particles of the silver nanoparticle composite obtained in Example 1. FIG. 実施例１、比較例２～３におけるＣＩＥ表色系におけるｘの値と測定開始時からの経過時間との関係を示すグラフである。6 is a graph showing the relationship between the value of x in the CIE color system and the elapsed time from the start of measurement in Example 1 and Comparative Examples 2 to 3. 実施例１で得られた銀ナノ粒子複合体の吸着から１週間経過後の倍率１０万倍の走査型電子顕微鏡写真である。2 is a scanning electron micrograph at a magnification of 100,000 times after one week from the adsorption of the silver nanoparticle composite obtained in Example 1. FIG. 実施例１で得られた銀ナノ粒子複合体の吸着から１週間経過後の倍率２万７千倍の走査型電子顕微鏡写真である。2 is a scanning electron micrograph at a magnification of 27,000 after one week from the adsorption of the silver nanoparticle composite obtained in Example 1. FIG. 比較例４で得られた銀ナノ粒子複合体の吸着から１週間経過後の倍率１０万倍の走査型電子顕微鏡写真である。4 is a scanning electron micrograph at a magnification of 100,000 times after one week from the adsorption of the silver nanoparticle composite obtained in Comparative Example 4. FIG. 比較例４で得られた銀ナノ粒子複合体の吸着から１週間経過後の倍率３万７千倍の走査型電子顕微鏡写真である。4 is a scanning electron micrograph at a magnification of 37,000 after one week from the adsorption of the silver nanoparticle composite obtained in Comparative Example 4. FIG. 実施例２～５におけるＣＩＥ表色系におけるｘの値と測定開始時からの経過時間との関係を示すグラフである。6 is a graph showing the relationship between the value of x in the CIE color system and the elapsed time from the start of measurement in Examples 2 to 5. 実施例２～５における退色時間と保存時間との関係を示すグラフである。6 is a graph showing the relationship between fading time and storage time in Examples 2 to 5. 実施例１、７～１０で得られた銀ナノ粒子複合体の吸着直後の状態をディスプレー上に表示した中間調画像を示す写真である。3 is a photograph showing a halftone image in which the state immediately after adsorption of the silver nanoparticle composite obtained in Examples 1 and 7 to 10 is displayed on a display. 実施例１、７～１０で得られた銀ナノ粒子複合体の吸着から４５６時間経過後の状態をディスプレー上に表示した中間調画像を示す写真である。3 is a photograph showing a halftone image in which a state after 456 hours has elapsed from the adsorption of the silver nanoparticle composite obtained in Examples 1 and 7 to 10 is displayed on a display. 実施例１１～１３で得られた組成物に対してγ線を照射する前の状態をディスプレー上に表示した中間調画像を示す写真である。6 is a photograph showing a halftone image in which the composition obtained in Examples 11 to 13 is displayed on a display in a state before γ-ray irradiation. 実施例１１～１３で得られた組成物に対して３００Ｇｙのγ線を照射した後の状態をディスプレー上に表示した中間調画像を示す写真である。2 is a photograph showing a halftone image in which a state obtained after irradiating 300 Gy of γ rays to the compositions obtained in Examples 11 to 13 is displayed on a display. 実施例１１～１３で得られた組成物に対して３００Ｇｙのγ線を照射する前後のＣＩＥ色度図を示すグラフである。2 is a graph showing CIE chromaticity diagrams before and after irradiating 300 Gy of γ rays to the compositions obtained in Examples 11 to 13. 実施例１４～１６、比較例７で得られた組成物に対してγ線を照射する前の状態をディスプレー上に表示した中間調画像を示す写真である。6 is a photograph showing a halftone image in which the composition obtained in Examples 14 to 16 and Comparative Example 7 is displayed on a display in a state before γ-ray irradiation. 実施例１４～１６、比較例７で得られた組成物に対して３０００Ｇｙのγ線を照射した後の状態をディスプレー上に表示した中間調画像を示す写真である。6 is a photograph showing a halftone image in which the composition obtained in Examples 14 to 16 and Comparative Example 7 is irradiated with 3000 Gy of γ-rays and displayed on the display. 実施例１４～１６、比較例７で得られた組成物に対して３０００Ｇｙのγ線を照射する前後のＣＩＥ色度図を示すグラフである。6 is a graph showing CIE chromaticity diagrams before and after irradiating 3000 Gy of γ rays to the compositions obtained in Examples 14 to 16 and Comparative Example 7. FIG.
　以下、本発明をその好適な実施形態に即して詳細に説明する。 Hereinafter, the present invention will be described in detail on the basis of preferred embodiments thereof.
　先ず、本発明の銀ナノ粒子複合体について説明する。本発明の銀ナノ粒子複合体は、複数の三角平板状銀ナノ粒子が、平板状金属酸化物粒子の平面上に吸着してなるものである。 First, the silver nanoparticle composite of the present invention will be described. The silver nanoparticle composite of the present invention is formed by adsorbing a plurality of triangular tabular silver nanoparticles on the flat surface of the tabular metal oxide particles.
　本発明に係る三角平板状銀ナノ粒子は、主平面の形状が三角形又は略三角形である。本発明において、前記三角平板状銀ナノ粒子の主平面とは、一つの粒子の外表面のうち、最大面積を有する平坦面及びそれに対向する平坦面のことをいう。また、本発明における略三角形とは、三角形の３つの角が欠損した形状であって、それぞれの角の欠損率が１６．７％以下であるものをいう。前記欠損率とは、前記略三角形の直線部を延長して形成される三角形面積（理想三角形面積）からのその角の欠損率であり、次式：
　角の欠損率（％）＝｛（理想三角形面積－対象角のみ欠損した略三角形面積）／理想三角形面積｝×１００
により求められる。前記式において、略三角形面積とは、前記略三角形の面と平行な外表面の投影図の面積のことを示し、前記理想三角形面積とは、前記略三角形の投影図の直線部を延長して形成される三角形の面積のことを示し、対象角のみ欠損した略三角形面積とは、前記理想三角形において欠損率を求める対象の角のみが前記略三角形の当該部分となっている形状の面積のことを示し、これらはいずれも走査型電子顕微鏡（ＳＥＭ）により測定して求めることができる。本発明に係る三角平板状銀ナノ粒子において、欠損率が前記上限を超える場合には、銀ナノ粒子の吸光度が低下すると共に吸光度のピーク波長が低波長側に遷移して本発明に係る三角平板状銀ナノ粒子の形状に由来する色を呈さなくなる傾向にある。 In the triangular tabular silver nanoparticles according to the present invention, the shape of the main plane is triangular or substantially triangular. In the present invention, the main plane of the triangular tabular silver nanoparticles refers to a flat surface having the largest area and an opposing flat surface among the outer surfaces of one particle. In addition, the substantially triangular shape in the present invention refers to a shape in which three corners of a triangle are missing, and the missing rate of each corner is 16.7% or less. The missing rate is a missing rate of the corner from a triangular area (ideal triangular area) formed by extending the straight portion of the substantially triangular shape, and the following formula:
Corner loss rate (%) = {(ideal triangle area−substantially triangular area where only the target corner is missing) / ideal triangle area} × 100
Is required. In the above formula, the substantially triangular area means the area of the projection on the outer surface parallel to the plane of the approximate triangle, and the ideal triangle area means that the straight portion of the approximate triangle is extended. Indicates the area of the triangle to be formed, and the approximate triangular area with only the target angle missing is the area of the shape in which only the target corner for which the defect rate is determined in the ideal triangle is the part of the approximate triangle. These can be obtained by measuring with a scanning electron microscope (SEM). In the triangular tabular silver nanoparticles according to the present invention, when the defect rate exceeds the upper limit, the absorbance of the silver nanoparticles decreases and the peak wavelength of the absorbance shifts to the lower wavelength side, and the triangular flat plate according to the present invention. There is a tendency that the color derived from the shape of the silver-like nanoparticles does not appear.
　また、本発明に係る三角平板状銀ナノ粒子とは、前記主平面の最長径が２０～１２０ｎｍの範囲にあるものをいう。前記主平面の最長径とは、前記主平面において最も長い直径のことをいい、前記主平面の形状が三角形の場合にはその最長辺の長さを指す。前記主平面の最長径が前記下限未満である場合及び前記上限を超える場合には、プラズモン吸収波長が可視域を外れるため銀ナノ粒子が呈色しなくなる。 Further, the triangular tabular silver nanoparticles according to the present invention are those having the longest diameter of the main plane in the range of 20 to 120 nm. The longest diameter of the main plane refers to the longest diameter in the main plane. When the main plane has a triangular shape, it indicates the length of the longest side. When the longest diameter of the main plane is less than the lower limit and exceeds the upper limit, the plasmon absorption wavelength is out of the visible range, so that the silver nanoparticles are not colored.
　また、通常、前記主平面の最長径は経時的に減少する傾向にあるが、本発明に係る複数の三角平板状銀ナノ粒子としては、前記主平面の初期平均最長径が２０～１２０ｎｍであることが必要である。前記主平面の初期平均最長径とは、前記複数の三角平板状銀ナノ粒子における初期最長径の平均値のことをいい、前記初期最長径とは、前記三角平板状銀ナノ粒子を本発明に係る平板状金属酸化物粒子の平面上に吸着せしめた直後（好ましくは前記吸着から０～１２０分）の、前記主平面の最長径のことをいう。初期平均最長径が前記下限未満である場合及び前記上限を超える場合には、プラズモン吸収波長が可視域を外れるため銀ナノ粒子が呈色しなくなる。 Usually, the longest diameter of the main plane tends to decrease with time, but the plurality of triangular tabular silver nanoparticles according to the present invention have an initial average longest diameter of the main plane of 20 to 120 nm. It is necessary. The initial average longest diameter of the main plane refers to the average value of the initial longest diameter in the plurality of triangular tabular silver nanoparticles, and the initial longest diameter refers to the triangular tabular silver nanoparticles in the present invention. The longest diameter of the main plane immediately after adsorbing on the flat surface of the flat metal oxide particles (preferably 0 to 120 minutes after the adsorption). When the initial average longest diameter is less than the lower limit and exceeds the upper limit, the plasmon absorption wavelength is out of the visible range, so the silver nanoparticles do not color.
　また、本発明に係る三角平板状銀ナノ粒子とは、厚さが５ｎｍ以上２０ｎｍ未満の範囲にあるものをいう。前記厚さとは、前記主平面間の平均距離のことを指す。厚さが前記下限未満である場合には、平板形状が不安定となるために三角平板状銀ナノ粒子の形状を維持できず、他方、前記上限を超える場合には、粒子の形状が平板でなくなるため、本発明に係る三角平板状銀ナノ粒子の形状に由来する色を呈さなくなる。 Further, the triangular tabular silver nanoparticles according to the present invention are those having a thickness in the range of 5 nm or more and less than 20 nm. The thickness refers to an average distance between the main planes. When the thickness is less than the lower limit, the shape of the triangular tabular silver nanoparticles cannot be maintained because the plate shape becomes unstable. On the other hand, when the thickness exceeds the upper limit, the shape of the particles is a flat plate. Therefore, the color derived from the shape of the triangular tabular silver nanoparticles according to the present invention is not exhibited.
　また、本発明に係る複数の三角平板状銀ナノ粒子としては、初期平均厚さが５ｎｍ以上２０ｎｍ未満であることが必要である。前記初期平均厚さとは、前記複数の三角平板状銀ナノ粒子における初期厚さの平均値のことをいい、前記初期厚さとは、前記三角平板状銀ナノ粒子を本発明に係る平板状金属酸化物粒子の平面上に吸着せしめた直後（好ましくは前記吸着から０～１２０分）の三角平板状銀ナノ粒子の厚さのことをいう。初期平均厚さが前記下限未満である場合には、平板形状が不安定となるために三角平板状銀ナノ粒子の形状を維持できず、他方、前記上限を超える場合には、粒子の形状が平板でなくなるため、本発明に係る三角平板状銀ナノ粒子の形状に由来する色を呈さなくなる。 In addition, the plurality of triangular tabular silver nanoparticles according to the present invention must have an initial average thickness of 5 nm or more and less than 20 nm. The initial average thickness refers to an average value of initial thicknesses of the plurality of triangular tabular silver nanoparticles, and the initial thickness refers to the tabular metal oxidation of the triangular tabular silver nanoparticles according to the present invention. This refers to the thickness of the triangular tabular silver nanoparticles immediately after adsorbing on the plane of the product particles (preferably 0 to 120 minutes after the adsorption). When the initial average thickness is less than the lower limit, the shape of the triangular tabular silver nanoparticles cannot be maintained because the tabular shape becomes unstable. Since it is no longer a flat plate, it does not exhibit a color derived from the shape of the triangular tabular silver nanoparticles according to the present invention.
　なお、本発明において、本発明に係る三角平板状銀ナノ粒子の主平面の最長径、主平面の初期平均最長径、厚さ及び初期平均厚さはいずれも、走査型電子顕微鏡（ＳＥＭ）又は透過型電子顕微鏡（ＴＥＭ）により測定することで求めることができる。 In the present invention, the longest diameter of the main plane of the triangular tabular silver nanoparticles according to the present invention, the initial average longest diameter, the thickness, and the initial average thickness of the main plane are all determined by a scanning electron microscope (SEM) or It can obtain | require by measuring with a transmission electron microscope (TEM).
　さらに、本発明に係る複数の三角平板状銀ナノ粒子としては、初期平均アスペクト比（初期平均最長径／初期平均厚さ）が４～２４であることが好ましい。初期平均アスペクト比が前記下限未満である場合には、粒子の形状が平板でなくなるため、本発明に係る三角平板状銀ナノ粒子の形状に由来する色を呈さなくなる傾向にあり、他方、前記上限を超える場合には、平板形状が不安定となるために三角平板状銀ナノ粒子の形状を維持できなくなり、本発明に係る三角平板状銀ナノ粒子の形状に由来する色を呈さなくなる傾向にある。 Furthermore, the plurality of triangular tabular silver nanoparticles according to the present invention preferably have an initial average aspect ratio (initial average longest diameter / initial average thickness) of 4 to 24. When the initial average aspect ratio is less than the lower limit, the shape of the grains is not a flat plate, and therefore tends not to exhibit a color derived from the shape of the triangular tabular silver nanoparticles according to the present invention, while the upper limit is In the case of exceeding, since the plate shape becomes unstable, the shape of the triangular tabular silver nanoparticles cannot be maintained, and the color derived from the shape of the triangular tabular silver nanoparticles according to the present invention tends not to be exhibited. .
　また、本発明に係る複数の三角平板状銀ナノ粒子としては、前記主平面の初期平均面積が１７３～６２３６ｎｍ２であることが好ましい。前記主平面の初期平均面積とは、前記複数の三角平板状銀ナノ粒子における主平面の初期面積の平均値のことをいい、前記主平面の初期面積とは、前記三角平板状銀ナノ粒子を本発明に係る平板状金属酸化物粒子の平面上に吸着せしめた直後（好ましくは前記吸着から０～１２０分）の、主平面と平行な外表面の投影面積のことをいい、走査型電子顕微鏡（ＳＥＭ）又は透過型電子顕微鏡（ＴＥＭ）により測定して求めることができる。 Further, in the plurality of triangular tabular silver nanoparticles according to the present invention, the initial average area of the main plane is preferably 173 to 6236 nm 2 . The initial average area of the main plane refers to an average value of the initial area of the main plane in the plurality of triangular tabular silver nanoparticles, and the initial area of the main plane refers to the triangular tabular silver nanoparticles. The projected area of the outer surface parallel to the main plane immediately after adsorbing on the plane of the flat metal oxide particles according to the present invention (preferably 0 to 120 minutes after the adsorption). (SEM) or a transmission electron microscope (TEM).
　本発明に係る平板状金属酸化物粒子は、前記複数の三角平板状銀ナノ粒子の初期平均最長径の１６．７～５００倍の平均直径を有する平面を有するものである。前記平面とは、その表面における凹部の最下点と凸部の頂点との間の高低差（凹凸の高低差）が１．３ｎｍ以下にある面のことをいい、前記凹凸の高低差は、透過型電子顕微鏡（ＴＥＭ）により測定することができる。また、本発明において、前記平板状金属酸化物粒子の有する平面の平均直径とは、平板状金属酸化物粒子の平面表面の平均投影面積と等しい面積をもつ円の直径のことをいい、走査型電子顕微鏡（ＳＥＭ）又は透過型電子顕微鏡（ＴＥＭ）により測定して求めることができる。前記平面の平均直径が前記下限未満である場合には、三角平板状銀ナノ粒子の形状変化を抑制することが困難になり、他方、前記上限を超える場合には、平板状金属酸化物粒子が破損しやすくなる。 The tabular metal oxide particles according to the present invention have a plane having an average diameter of 16.7 to 500 times the initial average longest diameter of the plurality of triangular tabular silver nanoparticles. The plane means a surface having a height difference between the lowest point of the concave portion on the surface and the top of the convex portion (height difference of the unevenness) of 1.3 nm or less. It can be measured by a transmission electron microscope (TEM). In the present invention, the average diameter of the flat surface of the flat metal oxide particles means a diameter of a circle having an area equal to the average projected area of the flat surface of the flat metal oxide particles. It can be determined by measuring with an electron microscope (SEM) or a transmission electron microscope (TEM). When the average diameter of the plane is less than the lower limit, it becomes difficult to suppress the shape change of the triangular tabular silver nanoparticles, and on the other hand, when the upper limit is exceeded, the tabular metal oxide particles are It becomes easy to break.
　本発明に係る平板状金属酸化物粒子としては、前記平面を少なくとも１つ以上有していればよく、粒子全体の形状が概略平板状とみなすことが可能な直方体であっても多面体であってもよいが、前記表面に吸着される三角平板状銀ナノ粒子の面がより配向し、１つの銀ナノ粒子当たりの平均吸光度がより向上する傾向にあるという観点から、アスペクト比（平面の平均直径／平均厚さ）が１０～１００の平板状であることが好ましい。アスペクト比が前記下限未満である場合には、有効な吸収に寄与する三角平板状銀ナノ粒子の割合が低くなる傾向にあり、例えば、前記アスペクト比が１の立方体では吸着された全三角平板状銀ナノ粒子の５／６が有効な吸収に寄与しなくなる。他方、前記上限を超える場合には、平板状金属酸化物粒子が破損しやすくなる傾向にある。なお、本発明に係る平板状金属酸化物粒子の厚さは透過型電子顕微鏡（ＴＥＭ）により測定して求めることができる。 The flat metal oxide particles according to the present invention need only have at least one of the planes, and even when the shape of the whole particle is a rectangular parallelepiped that can be regarded as a substantially flat plate, However, from the viewpoint that the plane of the triangular tabular silver nanoparticles adsorbed on the surface is more oriented and the average absorbance per silver nanoparticle tends to be improved, the aspect ratio (average diameter of the plane) / Average thickness) is preferably 10 to 100. When the aspect ratio is less than the lower limit, the proportion of triangular tabular silver nanoparticles that contribute to effective absorption tends to be low. For example, in a cube with an aspect ratio of 1, the adsorbed all triangular tabular 5/6 of the silver nanoparticles will not contribute to effective absorption. On the other hand, when it exceeds the upper limit, the flat metal oxide particles tend to be damaged. The thickness of the flat metal oxide particles according to the present invention can be determined by measuring with a transmission electron microscope (TEM).
　また、本発明に係る平板状金属酸化物粒子は、ｐＨ５～７におけるゼータ電位が正の金属酸化物からなるものである。ゼータ電位が０又は負である場合には、その表面に前記三角平板状銀ナノ粒子を十分に吸着できなくなる。また、前記ゼータ電位としては、熱エネルギーにより吸着が擾乱される傾向にあるという観点から、３００Ｋ、ｐＨ５～７において＋１０ｍＶ以上であることが好ましく、＋２５．８ｍＶ以上であることがより好ましい。このようなゼータ電位を有する金属酸化物としては、α－アルミナ、γ－アルミナ、チタニア及び酸化亜鉛が挙げられ、これらのうちの１種を単独で用いても２種以上を組み合わせて用いてもよい。これらの中でも、等電点がｐＨ９であり、ｐＨ７において十分に高い正のゼータ電位を有する傾向にあるという観点から、本発明に係る平板状金属酸化物粒子としては、α－アルミナからなるものであることがより好ましい。 In addition, the flat metal oxide particles according to the present invention are made of a metal oxide having a positive zeta potential at pH 5-7. When the zeta potential is 0 or negative, the triangular tabular silver nanoparticles cannot be sufficiently adsorbed on the surface. Further, the zeta potential is preferably +10 mV or more at 300 K and pH 5 to 7 and more preferably +25.8 mV or more from the viewpoint that adsorption tends to be disturbed by thermal energy. Examples of such metal oxides having a zeta potential include α-alumina, γ-alumina, titania, and zinc oxide. One of these may be used alone, or two or more may be used in combination. Good. Among these, the plate-like metal oxide particles according to the present invention are composed of α-alumina from the viewpoint that the isoelectric point is pH 9 and tends to have a sufficiently high positive zeta potential at pH 7. More preferably.
　本発明の銀ナノ粒子複合体は、前記複数の三角平板状銀ナノ粒子が、前記平板状金属酸化物粒子の前記平面上に吸着してなるものであり、前記平板状金属酸化物粒子と、前記平面上に吸着されている複数の銀ナノ粒子とを備えている。前記銀ナノ粒子とは、銀からなる粒子径が１～１５０ｎｍ程度の粒子であり、球状粒子であっても平板状粒子であってもよい。本発明に係る前記三角平板状銀ナノ粒子は、前記銀ナノ粒子に含まれる。 The silver nanoparticle composite of the present invention is formed by adsorbing the plurality of triangular tabular silver nanoparticles on the plane of the tabular metal oxide particles, and the tabular metal oxide particles, A plurality of silver nanoparticles adsorbed on the plane. The silver nanoparticles are particles made of silver and having a particle diameter of about 1 to 150 nm, and may be spherical particles or tabular particles. The triangular tabular silver nanoparticles according to the present invention are included in the silver nanoparticles.
　本発明においては、前記平板状金属酸化物粒子と前記複数の三角平板状銀ナノ粒子とから、前記平板状金属酸化物粒子の平面上に前記複数の三角平板状銀ナノ粒子が吸着された銀ナノ粒子複合体が得られるが、前述のように、通常は前記三角平板状銀ナノ粒子の主平面の最長径は経時的に減少するため、前記三角平板状銀ナノ粒子が球状等の三角平板状でない形状の銀ナノ粒子へと変化する傾向にある。しかしながら、本発明の銀ナノ粒子複合体においては、前記平板状金属酸化物粒子の平面上において、前記複数の銀ナノ粒子の全個数のうち、７５％以上の銀ナノ粒子が、主平面の形状が三角形又は略三角形であり、前記主平面の最長径が２０～１２０ｎｍであり且つ厚さが５ｎｍ以上２０ｎｍ未満であるという条件を満たす形状を維持している三角平板状銀ナノ粒子である。 In the present invention, silver in which the plurality of triangular tabular silver nanoparticles are adsorbed on the plane of the tabular metal oxide particles from the tabular metal oxide particles and the plurality of triangular tabular silver nanoparticles. Although a nanoparticle composite is obtained, as described above, since the longest diameter of the main plane of the triangular tabular silver nanoparticles usually decreases with time, the triangular tabular silver nanoparticle is a triangular plate such as a sphere. There is a tendency to change to silver nanoparticles of a non-shaped shape. However, in the silver nanoparticle composite of the present invention, 75% or more of silver nanoparticles out of the total number of the plurality of silver nanoparticles are in the shape of the main plane on the plane of the flat metal oxide particles. Is a triangular or substantially triangular shape, and is a triangular tabular silver nanoparticle having a shape that satisfies the condition that the longest diameter of the main plane is 20 to 120 nm and the thickness is 5 nm or more and less than 20 nm.
　本発明において、前記銀ナノ粒子の全個数における前記形状を維持している三角平板状銀ナノ粒子の割合は、走査型電子顕微鏡（ＳＥＭ）により、前記平面上に吸着されている任意の３０個以上の銀ナノ粒子の主平面の最長径及び厚さ、並びに、銀ナノ粒子が略三角形の主平面を有する場合にはその面積及び理想三角形の面積を測定し、これにより測定された数値に基いて、測定した全銀ナノ粒子の個数に対する、前記形状を維持している三角平板状銀ナノ粒子の割合を計算することにより求めることができる。また、より吸光度のピークをシャープにすることができる傾向にあるという観点から、前記形状を維持している三角平板状銀ナノ粒子の割合としては、前記複数の銀ナノ粒子の全個数のうち、７７％以上であることが好ましい。 In the present invention, the proportion of triangular tabular silver nanoparticles maintaining the shape in the total number of the silver nanoparticles may be any 30 adsorbed on the plane by a scanning electron microscope (SEM). When the silver nanoparticle has a substantially triangular principal plane, the area and the ideal triangle area are measured and the measured values are based on the measured values. The ratio of the triangular tabular silver nanoparticles maintaining the shape to the number of all silver nanoparticles measured can be calculated. In addition, from the viewpoint that the peak of absorbance can be sharpened, the proportion of triangular tabular silver nanoparticles maintaining the shape is the total number of the plurality of silver nanoparticles, It is preferably 77% or more.
　本発明の銀ナノ粒子複合体においては、このように形状が維持された三角平板状銀ナノ粒子を多く含有しているため、その三角平板状の形状に由来したプラズモン吸収により、安定して呈色することができる。なお、本発明においては、前記プラズモン吸収ピーク波長が５５０～６５０ｎｍの範囲にあることが好ましい。 Since the silver nanoparticle composite of the present invention contains a large amount of triangular tabular silver nanoparticles whose shape is maintained in this way, it is stably exhibited by plasmon absorption derived from the triangular tabular shape. Can be color. In the present invention, the plasmon absorption peak wavelength is preferably in the range of 550 to 650 nm.
　また、本発明の銀ナノ粒子複合体においては、前記平板状金属酸化物粒子の前記平面上において、前記平面上に吸着されている前記三角平板状銀ナノ粒子の占有面積率が１～１００％であることが好ましく、１０～１００％であることがより好ましく、１０～２０％であることがさらに好ましい。前記占有面積率が前記下限未満である場合には、三角平板状銀ナノ粒子の呈する色が薄くなる傾向にあり、他方、前記上限を超える場合には、吸光度が可視域で底上げされるために三角平板状銀ナノ粒子の呈する色が暗くなったり、経済的に不利となったりする傾向にある。なお、本発明における前記占有面積率とは、走査型電子顕微鏡（ＳＥＭ）により平板状金属酸化物粒子の平面を観察し、観察視野内（倍率１０万倍、０．４×０．４μｍの領域）における三角平板状銀ナノ粒子の占有面積率を測定して得られる値である。 Further, in the silver nanoparticle composite of the present invention, the occupation area ratio of the triangular tabular silver nanoparticles adsorbed on the plane is 1 to 100% on the plane of the tabular metal oxide particles. It is preferably 10 to 100%, more preferably 10 to 20%. When the occupied area ratio is less than the lower limit, the color exhibited by the triangular tabular silver nanoparticles tends to be thin, whereas when the upper limit is exceeded, the absorbance is raised in the visible range. The color exhibited by the triangular tabular silver nanoparticles tends to be dark or economically disadvantageous. The occupied area ratio in the present invention refers to a flat metal oxide particle plane observed with a scanning electron microscope (SEM), and within an observation field (magnification 100,000 times, 0.4 × 0.4 μm region). This is a value obtained by measuring the occupation area ratio of the triangular tabular silver nanoparticles in FIG.
　本発明の銀ナノ粒子複合体において、前記三角平板状銀ナノ粒子と前記平板状金属酸化物粒子との質量比（三角平板状銀ナノ粒子の全質量：平板状金属酸化物粒子の質量）としては、１：１００～３０：１００であることが好ましく、１．５：１００～３０：１００であることがより好ましく、５：１００～１０：１００であることがさらに好ましい。前記平板状金属酸化物粒子に対する前記三角平板状銀ナノ粒子の割合が前記下限未満である場合には、銀ナノ粒子複合体において三角平板状銀ナノ粒子の形状が変化しやすくなる傾向にあり、他方、前記上限を超えて三角平板状銀ナノ粒子を含有させても、三角平板状銀ナノ粒子の形状変化の抑制効果はそれ以上向上せず、経済的に不利となる傾向にある。 In the silver nanoparticle composite of the present invention, the mass ratio of the triangular tabular silver nanoparticles to the tabular metal oxide particles (total mass of the triangular tabular silver nanoparticles: mass of the tabular metal oxide particles) Is preferably 1: 100 to 30: 100, more preferably 1.5: 100 to 30: 100, and even more preferably 5: 100 to 10: 100. When the ratio of the triangular tabular silver nanoparticles to the tabular metal oxide particles is less than the lower limit, the shape of the triangular tabular silver nanoparticles tends to change in the silver nanoparticle composite, On the other hand, even if the triangular tabular silver nanoparticles are contained beyond the upper limit, the effect of suppressing the shape change of the triangular tabular silver nanoparticles is not further improved and tends to be economically disadvantageous.
　次いで、本発明の銀ナノ粒子複合体懸濁液について説明する。本発明の銀ナノ粒子複合体懸濁液は、上記本発明の銀ナノ粒子複合体が水溶液中に懸濁されていることを特徴とするものである。本発明の銀ナノ粒子複合体懸濁液においては、前記三角平板状銀ナノ粒子の形状変化が十分に抑制されているため、長期間保存されても色の変化が抑制され、また、ハロゲンの存在下でも三角平板状銀ナノ粒子の形状が安定に維持される。 Next, the silver nanoparticle composite suspension of the present invention will be described. The silver nanoparticle composite suspension of the present invention is characterized in that the silver nanoparticle composite of the present invention is suspended in an aqueous solution. In the silver nanoparticle composite suspension of the present invention, since the shape change of the triangular tabular silver nanoparticles is sufficiently suppressed, the color change is suppressed even when stored for a long period of time. Even in the presence, the shape of triangular tabular silver nanoparticles is stably maintained.
　前記水溶液の溶媒としては、イオン交換、蒸留、濾過等の精製を施された水が挙げられる。このような水溶液において、銀ナノ粒子複合体の濃度としては、３～２８ｍｇ／ｍｌであることが好ましく、７～１４ｍｇ／ｍｌであることがより好ましい。濃度が前記下限未満である場合には、三角平板状銀ナノ粒子の形状が変化して色が変化しやすくなる傾向にあり、他方、前記上限を超えて銀ナノ粒子複合体を含有させても、三角平板状銀ナノ粒子の形状変化の抑制効果はそれ以上向上せず、経済的に不利となる傾向にある。 Examples of the solvent for the aqueous solution include water subjected to purification such as ion exchange, distillation, and filtration. In such an aqueous solution, the concentration of the silver nanoparticle composite is preferably 3 to 28 mg / ml, more preferably 7 to 14 mg / ml. When the concentration is less than the lower limit, the shape of the triangular tabular silver nanoparticles tends to change and the color tends to change, and on the other hand, the silver nanoparticle composite may be contained exceeding the upper limit. In addition, the effect of suppressing the shape change of the triangular tabular silver nanoparticles does not improve any more, and tends to be economically disadvantageous.
　前記水溶液のｐＨとしては、５以上であることが好ましく、銀ナノ粒子複合体が安定化され、負電位によって三角平板状銀ナノ粒子の形状の変化がより抑制されるという観点から、前記平板状金属酸化物粒子の等電点以上であることが好ましく、例えば、前記平板状金属酸化物粒子がα－アルミナである場合にはｐＨが９以上であることが好ましく、１０以上であることがより好ましい。また、前記平板状金属酸化物粒子がγ－アルミナである場合にはｐＨが８以上であることが好ましく、チタニアである場合にはｐＨが７以上であることが好ましく、酸化亜鉛である場合にはｐＨが１０以上であることが好ましい。 The pH of the aqueous solution is preferably 5 or more, from the viewpoint that the silver nanoparticle composite is stabilized and the change in the shape of the triangular tabular silver nanoparticles is further suppressed by the negative potential, the plate shape The isoelectric point of the metal oxide particles is preferably higher than the isoelectric point. For example, when the flat metal oxide particles are α-alumina, the pH is preferably 9 or higher, and more preferably 10 or higher. preferable. Further, when the plate-like metal oxide particles are γ-alumina, the pH is preferably 8 or more, and when it is titania, the pH is preferably 7 or more, and when it is zinc oxide. The pH is preferably 10 or more.
　また、本発明の銀ナノ粒子複合体懸濁液としては、本発明の効果を阻害しない範囲において、必要に応じて、ｐＨ調整剤、顔料、高分子化合物、界面活性剤、その他の金属ナノ粒子、半導体ナノ粒子、その他の金属酸化物粒子、タンパク質粒子等をさらに含有していてもよい。 In addition, as the silver nanoparticle composite suspension of the present invention, a pH adjuster, a pigment, a polymer compound, a surfactant, and other metal nanoparticles may be used as long as the effects of the present invention are not impaired. Further, it may further contain semiconductor nanoparticles, other metal oxide particles, protein particles and the like.
　次いで、本発明のγ線感応センサ形成用組成物及びγ線感応センサについて説明する。前記本発明の銀ナノ粒子複合体は、上述のようにハロゲンの存在下でも前記三角平板状銀ナノ粒子の形状変化が十分に抑制されるものであり、紫外線に対しても安定なものであるが、本発明者は、前記銀ナノ粒子複合体がγ線に対しては感応性を有しており、これに対してγ線を照射すると前記三角平板状銀ナノ粒子の呈する色が長波長側に変色又は退色することを見出した。従って、本発明の銀ナノ粒子複合体は、γ線が照射されることにより変退色するγ線感応材料として用いることができる。 Next, the γ-ray sensitive sensor forming composition and γ-ray sensitive sensor of the present invention will be described. As described above, the silver nanoparticle composite of the present invention sufficiently suppresses the shape change of the triangular tabular silver nanoparticles even in the presence of halogen, and is stable to ultraviolet rays. However, the present inventor has said that the silver nanoparticle composite has sensitivity to γ rays, and when the γ rays are irradiated to the silver nanoparticle composite, the color of the triangular tabular silver nanoparticles exhibits a long wavelength. It was found that the color changed or faded to the side. Therefore, the silver nanoparticle composite of the present invention can be used as a γ-ray sensitive material that discolors and fades when irradiated with γ-rays.
　前記γ線の吸収線量としては、３０Ｇｙ以上であることが好ましく、３００Ｇｙ以上であることがより好ましい。また、このようなγ線の線源としては、コバルト６０、セシウム１３７等が挙げられる。 The absorbed dose of the γ rays is preferably 30 Gy or more, and more preferably 300 Gy or more. Examples of such a gamma ray source include cobalt 60 and cesium 137.
　本発明のγ線感応センサ形成用組成物及びγ線感応センサはこのような本発明の銀ナノ粒子複合体のγ線に対する感応性を利用したものであり、前記γ線感応センサ形成用組成物は、水及びγ線感応材料を含有するγ線感応センサ形成用組成物であって、ｐＨが６以上９．７未満であり、前記γ線感応材料として前記本発明の銀ナノ粒子複合体を用いるものである。 The composition for forming a gamma ray sensitive sensor and the gamma ray sensitive sensor of the present invention utilize the sensitivity to the gamma rays of the silver nanoparticle composite of the present invention, and the composition for forming a gamma ray sensitive sensor. Is a composition for forming a γ-ray sensitive sensor containing water and a γ-ray sensitive material, and has a pH of 6 or more and less than 9.7, and the silver nanoparticle composite of the present invention is used as the γ-ray sensitive material. It is what is used.
　本発明のγ線感応センサ形成用組成物においては、ｐＨが６以上９．７未満であることが必要である。ｐＨが前記下限未満である場合には、三角平板状銀ナノ粒子の形状が変化しやすくなり、他方、前記上限を超える場合には、γ線を照射しても変退色が起こらない。また、このようなｐＨとしては、より具体的には、６～９．６であることが好ましく、より少ないγ線量で変退色が起こる傾向にあるという観点から、６～８であることがより好ましい。 In the composition for forming a γ-ray sensitive sensor of the present invention, the pH needs to be 6 or more and less than 9.7. When the pH is less than the lower limit, the shape of the triangular tabular silver nanoparticles tends to change. On the other hand, when the pH exceeds the upper limit, no discoloration occurs even when γ rays are irradiated. More specifically, such a pH is preferably 6 to 9.6, and more preferably 6 to 8 from the viewpoint that discoloration tends to occur with a smaller γ dose. preferable.
　本発明のγ線感応センサ形成用組成物において、前記水としては、イオン交換、蒸留、濾過等の精製を施された水が挙げられる。また、このようなγ線感応センサ形成用組成物において、銀ナノ粒子複合体の濃度としては、変退色前において、１００ｍｇ／ｍｌ以下であることが好ましく、１～１０ｍｇ／ｍｌであることがより好ましい。前記ナノ粒子複合体の変退色前の濃度が前記下限未満では銀ナノ粒子複合体の色自体を目視で確認することが困難となる傾向にあり、他方、前記上限を超えると変退色の程度を目視で認識することが困難となる傾向にある。 In the composition for forming a γ-ray sensitive sensor of the present invention, examples of the water include water subjected to purification such as ion exchange, distillation, and filtration. In such a composition for forming a γ-ray sensitive sensor, the concentration of the silver nanoparticle composite is preferably 100 mg / ml or less, more preferably 1 to 10 mg / ml before discoloration. preferable. If the concentration before the color change of the nanoparticle composite is less than the lower limit, it tends to be difficult to visually check the color of the silver nanoparticle composite itself. It tends to be difficult to recognize visually.
　また、本発明のγ線感応センサ形成用組成物としては、本発明の効果を阻害しない範囲において、必要に応じて、ｐＨ調整剤、顔料、高分子化合物、界面活性剤、その他の金属ナノ粒子、半導体ナノ粒子、その他の金属酸化物粒子、タンパク質粒子等をさらに含有していてもよい。 In addition, the composition for forming a γ-ray sensitive sensor of the present invention includes a pH adjuster, a pigment, a polymer compound, a surfactant, and other metal nanoparticles as necessary, as long as the effects of the present invention are not impaired. Further, it may further contain semiconductor nanoparticles, other metal oxide particles, protein particles and the like.
　本発明のγ線感応センサは、前記本発明のγ線感応センサ形成用組成物により形成される。このようなγ線感応センサの形成方法及びγ線感応センサの形態としては、前記水が残留する形成方法及び形態であることが好ましく、例えば、前記γ線感応センサ形成用組成物をポリエチレンフィルム等からなる包装容器内に密封して包装体を得る方法や、薄膜ガラスで密封した包装体を得る方法が挙げられる。 The γ-ray sensitive sensor of the present invention is formed of the γ-ray sensitive sensor forming composition of the present invention. As a method for forming such a γ-ray sensitive sensor and a form of the γ-ray sensitive sensor, it is preferable to use a method and a form in which the water remains, for example, the composition for forming the γ-ray sensitive sensor is a polyethylene film or the like. And a method of obtaining a package by sealing in a packaging container comprising the above, and a method of obtaining a package sealed with thin film glass.
　次いで、本発明の銀ナノ粒子複合体の製造方法について説明する。本発明の銀ナノ粒子複合体の製造方法は、前記複数の三角平板状銀ナノ粒子と前記平板状金属酸化物粒子とをｐＨ５～７の水中に共存せしめることにより、前記平板状金属酸化物粒子の前記平面上に前記複数の銀ナノ粒子を吸着せしめ、本発明の銀ナノ粒子複合体を得る製造方法である。 Next, a method for producing the silver nanoparticle composite of the present invention will be described. In the method for producing a silver nanoparticle composite of the present invention, the plurality of triangular tabular silver nanoparticles and the tabular metal oxide particles are allowed to coexist in water having a pH of 5 to 7, thereby The silver nanoparticle composite of the present invention is obtained by adsorbing the plurality of silver nanoparticles on the flat surface.
　本発明の製造方法に用いる複数の三角平板状銀ナノ粒子としては、主平面の形状が三角形又は略三角形であり、前記主平面の初期平均最長径が２０～１２０ｎｍであり且つ初期平均厚さが５ｎｍ以上２０ｎｍ未満であることが必要であり、前記主平面の形状、前記主平面の初期平均最長径、前記初期平均厚さとしては、前記本発明の銀ナノ粒子複合体において述べたとおりである。 As the plurality of triangular tabular silver nanoparticles used in the production method of the present invention, the shape of the main plane is triangular or substantially triangular, the initial average longest diameter of the main plane is 20 to 120 nm, and the initial average thickness is 5 nm or more and less than 20 nm, and the shape of the main plane, the initial average longest diameter of the main plane, and the initial average thickness are as described in the silver nanoparticle composite of the present invention. .
　このような複数の三角平板状銀ナノ粒子としては、より本発明の銀ナノ粒子複合体に適した三角平板状銀ナノ粒子が得られ、効率よく、且つ、再現性よく本発明の銀ナノ粒子複合体を得ることができるという観点から、先ず複数の銀ナノ粒子を合成し、次いで、合成した複数の銀ナノ粒子における前記三角平板状銀ナノ粒子の含有比率を遠心分離によって調整することにより得られたものを用いることが好ましい。 As such a plurality of triangular tabular silver nanoparticles, triangular tabular silver nanoparticles more suitable for the silver nanoparticle composite of the present invention can be obtained, and the silver nanoparticles of the present invention can be efficiently and reproducibly obtained. From the viewpoint that a composite can be obtained, first, a plurality of silver nanoparticles are synthesized, and then obtained by adjusting the content ratio of the triangular tabular silver nanoparticles in the synthesized silver nanoparticles by centrifugation. It is preferable to use those obtained.
　前記複数の銀ナノ粒子の合成方法としては、公知の方法を適宜採用することができ、例えば、還元溶液中に溶解させた銀化合物に光照射をすることにより銀ナノ粒子を合成する方法が挙げられる。前記還元溶液としては、溶媒、還元剤、保護剤及び必要に応じて錯化剤を含有する水溶液が挙げられる。前記溶媒としては、水、超臨界水、水溶性有機溶媒（メタノール、エタノール、プロパノール、イソプロパノール、ブタノール、アセトン、アセトニトリル等）、水と前記水溶性有機溶媒との混合溶媒、ジメチルスルホキシド等が挙げられ、中でも水を用いることが好ましい。前記還元剤としては、水素化ホウ素ナトリウム（ＮａＢＨ４）、アスコルビン酸、ヒドロキシルアミン（ＮＨ２ＯＨ）、ヒドラジン（Ｎ２Ｈ４）、ポリオール、放射線等が挙げられ、中でも水素化ホウ素ナトリウムを用いることが好ましい。前記保護剤としては、ビス（ｐ－スルホナトフェニル）フェニルホスフィン二カリウム、ポリビニルピロリドン等が挙げられ、中でもビス（ｐ－スルホナトフェニル）フェニルホスフィン二カリウムを用いることが好ましい。前記錯化剤としては、クエン酸等が挙げられる。 As a method for synthesizing the plurality of silver nanoparticles, a known method can be appropriately employed. For example, a method of synthesizing silver nanoparticles by irradiating light to a silver compound dissolved in a reducing solution can be mentioned. It is done. Examples of the reducing solution include an aqueous solution containing a solvent, a reducing agent, a protective agent, and, if necessary, a complexing agent. Examples of the solvent include water, supercritical water, water-soluble organic solvents (methanol, ethanol, propanol, isopropanol, butanol, acetone, acetonitrile, etc.), a mixed solvent of water and the water-soluble organic solvent, dimethyl sulfoxide, and the like. Of these, it is preferable to use water. Examples of the reducing agent include sodium borohydride (NaBH 4 ), ascorbic acid, hydroxylamine (NH 2 OH), hydrazine (N 2 H 4 ), polyol, radiation, etc. Among them, sodium borohydride is used. Is preferred. Examples of the protective agent include bis (p-sulfonatophenyl) phenylphosphine dipotassium, polyvinylpyrrolidone and the like. Among them, bis (p-sulfonatophenyl) phenylphosphine dipotassium is preferably used. Examples of the complexing agent include citric acid.
　前記銀化合物としては、銀の水酸化物、塩化物、硝酸塩、硫酸塩、酢酸塩、亜硫酸塩、無機錯塩等が挙げられ、中でも硝酸塩を用いることが好ましい。このような銀化合物の前記還元溶液中における濃度としては、０．１～１ｍｍｏｌ／Ｌであることが好ましい。 Examples of the silver compound include silver hydroxide, chloride, nitrate, sulfate, acetate, sulfite, and inorganic complex salt. Among these, nitrate is preferably used. The concentration of such a silver compound in the reducing solution is preferably 0.1 to 1 mmol / L.
　前記光照射の光源としては、白色系蛍光灯、橙色系蛍光灯、白熱灯、キセノン光源、レーザー等が挙げられ、中でも安価であるという観点からは、白色系蛍光灯、橙色系蛍光灯、白熱灯が好ましい。また、前記光照射の時間としては、５０時間以上であることが好ましく、７２～９６時間であることがより好ましい。 Examples of the light source for the light irradiation include white fluorescent lamps, orange fluorescent lamps, incandescent lamps, xenon light sources, and lasers. Among these, white fluorescent lamps, orange fluorescent lamps, incandescent lamps are particularly inexpensive. A lamp is preferred. The light irradiation time is preferably 50 hours or more, and more preferably 72 to 96 hours.
　前記遠心分離としては、回転数が１２００～１６４０Ｇであり、時間が３０～６０分であることが好ましい。前記回転数が前記下限未満である場合には、溶液から銀ナノ粒子を回収できなくなる傾向にあり、他方、前記上限を超える場合には、三角平板状銀ナノ粒子以外の銀ナノ粒子も多く沈殿するため、回収された銀ナノ粒子における三角平板状銀ナノ粒子の含有比率が低下する傾向にある。また、前記時間が前記下限未満である場合には、溶液から銀ナノ粒子を回収できなくなる傾向にあり、他方、前記上限を超えて遠心分離を行ってもそれ以上三角平板状銀ナノ粒子は回収できず、経済的に不利となる傾向にある。 As the centrifugation, the number of rotations is preferably 1200 to 1640 G, and the time is preferably 30 to 60 minutes. When the rotational speed is less than the lower limit, silver nanoparticles cannot be recovered from the solution. On the other hand, when the upper limit is exceeded, a large amount of silver nanoparticles other than triangular tabular silver nanoparticles are precipitated. Therefore, the content ratio of the triangular tabular silver nanoparticles in the collected silver nanoparticles tends to decrease. Further, when the time is less than the lower limit, the silver nanoparticles tend not to be recovered from the solution. On the other hand, even if the centrifugation exceeds the upper limit, more triangular tabular silver nanoparticles are recovered. It cannot be done and tends to be economically disadvantageous.
　このような方法により、前記遠心分離後の沈殿画分として本発明に係る複数の三角平板状銀ナノ粒子を含有する複数の銀ナノ粒子を得ることができる。このようにして得られた前記複数の銀ナノ粒子は青～紫色の懸濁物として得られ、この懸濁物４０μｌに純水９００μｌを加えて測定したときの吸光度としては、４００～７５０ｎｍの範囲内にあることが好ましく、５８０～７５０ｎｍの範囲内にあることがより好ましい。 By such a method, a plurality of silver nanoparticles containing a plurality of triangular tabular silver nanoparticles according to the present invention can be obtained as the precipitate fraction after the centrifugation. The silver nanoparticles thus obtained are obtained as a blue to purple suspension, and the absorbance when measured by adding 900 μl of pure water to 40 μl of this suspension is in the range of 400 to 750 nm. Preferably, it is within the range of 580 to 750 nm.
　このようにして得られた複数の銀ナノ粒子を本発明の製造方法に用いる場合には、前記銀ナノの粒子の前個数のうちの７７質量％以上が本発明に係る三角平板状銀ナノ粒子であることが必要である。本発明に係る三角平板状銀ナノ粒子の含有量が前記下限未満となる場合には、前記平面上に吸着されている銀ナノ粒子の全個数のうちの７５％以上が本発明に係る三角平板状銀ナノ粒子である銀ナノ粒子複合体を得ることができない。 When a plurality of silver nanoparticles obtained in this way are used in the production method of the present invention, 77% by mass or more of the previous number of the silver nanoparticle is triangular tabular silver nanoparticles according to the present invention. It is necessary to be. When the content of the triangular tabular silver nanoparticles according to the present invention is less than the lower limit, 75% or more of the total number of silver nanoparticles adsorbed on the plane is the triangular flat plate according to the present invention. A silver nanoparticle composite that is a silver nanoparticle cannot be obtained.
　本発明の製造方法に用いる平板状金属酸化物粒子としては、ｐＨ５～７におけるゼータ電位が正の金属酸化物からなり、且つ、前記三角平板状銀ナノ粒子の初期平均最長径の１６．７～５００倍の平均直径を有する平面を有する平板状金属酸化物粒子であることが必要であり、前記ゼータ電位及び前記平面としては、前記本発明の銀ナノ粒子複合体において述べたとおりである。 The plate-like metal oxide particles used in the production method of the present invention are made of a metal oxide having a positive zeta potential at a pH of 5 to 7, and the initial average longest diameter of the triangular plate-like silver nanoparticles is 16.7 to The flat metal oxide particles having a plane having an average diameter of 500 times are necessary, and the zeta potential and the plane are as described in the silver nanoparticle composite of the present invention.
　このような平板状金属酸化物粒子としては、公知の方法により得ることができ、例えば、金属化合物を直接熱分解する方法や、金属化合物の蒸気に対して酸素又は水蒸気を高温で反応させる方法が挙げられる。前記金属としては、アルミニウム、チタン、亜鉛等が挙げられ、中でも、光触媒性がなく、吸着した銀ナノ粒子を酸化しない傾向にあるという観点から、アルミニウムが好ましい。前記金属化合物としては、前記金属の水酸化物、塩化物、硝酸塩、硫酸塩、酢酸塩、亜硫酸塩、無機錯塩等が挙げられる。前記熱分解や酸素又は水蒸気を反応させる条件としては、金属化合物の種類により適宜調整することができる。また、本発明の製造方法に用いる平板状金属酸化物粒子としては、市販のものを適宜用いてもよい。 Such flat metal oxide particles can be obtained by a known method, for example, a method in which a metal compound is directly pyrolyzed, or a method in which oxygen or water vapor is reacted at high temperature with the vapor of the metal compound. Can be mentioned. Examples of the metal include aluminum, titanium, zinc, and the like. Among them, aluminum is preferable from the viewpoint that it has no photocatalytic property and does not tend to oxidize the adsorbed silver nanoparticles. Examples of the metal compound include metal hydroxides, chlorides, nitrates, sulfates, acetates, sulfites, and inorganic complex salts. Conditions for the thermal decomposition and the reaction of oxygen or water vapor can be appropriately adjusted depending on the type of metal compound. Moreover, as a flat metal oxide particle used for the manufacturing method of this invention, you may use a commercially available thing suitably.
　本発明の製造方法において用いる水としては、イオン交換、蒸留、濾過等の精製を施された水が挙げられる。また、前記水としては、必要に応じて、ｐＨ調製剤、酸素等の気体等を含有していてもよい。本発明の製造方法においては、前記水のｐＨが５～７の範囲にあることが必要である。ｐＨが前記範囲から外れる場合には、前記三角平板状銀ナノ粒子の形状が変化したり、前記平板状金属酸化物粒子への前記三角平板状銀ナノ粒子の吸着が困難になる。また、前記ｐＨとしては、平板状金属酸化物粒子の表面が十分に正電荷を帯びる傾向にあるという観点から、５～６であることがより好ましい。 Examples of water used in the production method of the present invention include water that has been subjected to purification such as ion exchange, distillation, and filtration. Moreover, as said water, you may contain gas, such as a pH adjuster and oxygen, as needed. In the production method of the present invention, the pH of the water needs to be in the range of 5-7. When the pH deviates from the above range, the shape of the triangular tabular silver nanoparticles changes or it becomes difficult to adsorb the triangular tabular silver nanoparticles to the tabular metal oxide particles. The pH is more preferably 5 to 6 from the viewpoint that the surface of the tabular metal oxide particles tends to have a sufficient positive charge.
　前記複数の三角平板状銀ナノ粒子と前記平板状金属酸化物粒子とを前記水中に共存せしめる方法としては、特に制限されず、例えば、前記複数の三角平板状銀ナノ粒子と前記平板状金属酸化物粒子とを前記水中において混合した懸濁液を、３０秒間～１分間撹拌する方法が挙げられる。前記三角平板状銀ナノ粒子と前記平板状金属酸化物粒子との混合比（三角平板状銀ナノ粒子の質量：平板状金属酸化物粒子の質量）としては、１：１００～３０：１００であることが好ましく、１．５：１００～３０：１００であることがより好ましく、５：１００～１０：１００であることがさらに好ましい。前記平板状金属酸化物粒子に対する前記三角平板状銀ナノ粒子の割合が前記下限未満である場合には、得られる銀ナノ粒子複合体において三角平板状銀ナノ粒子の形状が変化しやすくなる傾向にあり、他方、前記上限を超えて三角平板状銀ナノ粒子を含有させても、得られる銀ナノ粒子複合体における三角平板状銀ナノ粒子の形状変化の抑制効果はそれ以上向上せず、経済的に不利となる傾向にある。 The method for allowing the plurality of triangular tabular silver nanoparticles and the tabular metal oxide particles to coexist in the water is not particularly limited, and for example, the plurality of triangular tabular silver nanoparticles and the tabular metal oxide Examples thereof include a method in which a suspension obtained by mixing product particles in water is stirred for 30 seconds to 1 minute. The mixing ratio of the triangular tabular silver nanoparticles and the tabular metal oxide particles (mass of triangular tabular silver nanoparticles: mass of tabular metal oxide particles) is 1: 100 to 30: 100. It is preferably 1.5: 100 to 30: 100, more preferably 5: 100 to 10: 100. When the ratio of the triangular tabular silver nanoparticles to the tabular metal oxide particles is less than the lower limit, the shape of the triangular tabular silver nanoparticles tends to change in the obtained silver nanoparticle composite. On the other hand, even when the triangular tabular silver nanoparticles are contained exceeding the upper limit, the effect of suppressing the shape change of the triangular tabular silver nanoparticles in the obtained silver nanoparticle composite is not further improved, and is economical. Tend to be disadvantageous.
　また、前記懸濁液の濃度としては、前記三角平板状銀ナノ粒子と前記平板状金属酸化物粒子との合計含有量が０．９～１．１ｍｇ／ｍｌとなるようにすることが好ましく、０．９～１．０ｍｇ／ｍｌとなるようにすることがより好ましい。濃度が前記下限未満である場合には、銀ナノ粒子の吸着量が不十分となる傾向にあり、他方、前記上限を超える場合には、吸着反応の効率が低下する傾向にある。 The concentration of the suspension is preferably such that the total content of the triangular tabular silver nanoparticles and the tabular metal oxide particles is 0.9 to 1.1 mg / ml, More preferably, the concentration is 0.9 to 1.0 mg / ml. When the concentration is less than the lower limit, the adsorption amount of the silver nanoparticles tends to be insufficient. On the other hand, when the concentration exceeds the upper limit, the efficiency of the adsorption reaction tends to decrease.
　このような方法により、懸濁液中に、前記平板状金属酸化物粒子の前記平面上に前記複数の三角平板状銀ナノ粒子が吸着された本発明の銀ナノ粒子複合体を得ることができる。本発明においては、この懸濁液から銀ナノ粒子複合体を遠心分離、濾過、乾燥等の方法によって本発明の銀ナノ粒子複合体の粉末を回収することができる。また、本発明においては、この懸濁液をそのまま又は分離、濃縮等することにより本発明の銀ナノ粒子複合体懸濁液とすることができ、必要に応じてｐＨを調整することにより、本発明のγ線感応センサ形成用組成物を得ることができる。なお、前記懸濁液を本発明の銀ナノ粒子複合体懸濁液とする場合には、銀ナノ粒子複合体がより安定化され、三角平板状銀ナノ粒子の形状の変化がより抑制されるという観点から、前記平板状金属酸化物粒子の等電点以上にｐＨを調整することが好ましい。 By such a method, the silver nanoparticle composite of the present invention in which the plurality of triangular tabular silver nanoparticles are adsorbed on the flat surface of the tabular metal oxide particles in a suspension can be obtained. . In the present invention, the silver nanoparticle composite powder of the present invention can be recovered from the suspension by a method such as centrifugation, filtration, and drying. In the present invention, the suspension can be used as it is or by separating, concentrating, etc. to obtain the silver nanoparticle composite suspension of the present invention, and by adjusting the pH as necessary, The composition for forming a gamma ray sensitive sensor of the invention can be obtained. When the suspension is the silver nanoparticle composite suspension of the present invention, the silver nanoparticle composite is more stabilized and the change in the shape of the triangular tabular silver nanoparticles is further suppressed. From this viewpoint, it is preferable to adjust the pH to be equal to or higher than the isoelectric point of the flat metal oxide particles.
　また、本発明の製造方法においては、前記平板状金属酸化物粒子の平面上に前記三角平板状銀ナノ粒子を吸着せしめた後に、密封容器内において５０時間以上保存する安定化工程をさらに備えることが好ましい。製造方法においてこのような安定化工程を備えることにより、より安定性に優れ、三角平板状銀ナノ粒子の形状変化をより抑制することができる銀ナノ粒子複合体を得られることを本発明者らは見出した。 Further, the production method of the present invention further includes a stabilization step of storing the triangular tabular silver nanoparticles on the plane of the tabular metal oxide particles and then storing them in a sealed container for 50 hours or more. Is preferred. By providing such a stabilization step in the production method, the present inventors can obtain a silver nanoparticle composite that is more stable and can further suppress the shape change of triangular tabular silver nanoparticles. Found.
　前記密封容器としては、特に制限されず、例えば、蓋つきのガラス瓶、蓋つきのプラスチックボトル等が挙げられる。本発明に係る安定化工程としては、前記平板状金属酸化物粒子と前記三角平板状銀ナノ粒子とを共存せしめた懸濁液をそのまま前記密封容器内に移して保存することが好ましいが、前記懸濁液にさらにｐＨ調製剤、高分子化合物、無機微粒子、タンパク質粒子等をさらに含有せしめてもよく、前記懸濁液から遠心分離、濾過、乾燥等の方法により回収した固形物を再度水中に懸濁した懸濁液を用いてもよい。前記水としては、イオン交換、蒸留、濾過等の精製を施された水が挙げられる。 The sealed container is not particularly limited, and examples thereof include a glass bottle with a lid and a plastic bottle with a lid. As the stabilization step according to the present invention, it is preferable that the suspension in which the tabular metal oxide particles and the triangular tabular silver nanoparticles coexist are transferred and stored in the sealed container as they are, The suspension may further contain a pH adjuster, a polymer compound, inorganic fine particles, protein particles, etc., and the solid recovered from the suspension by a method such as centrifugation, filtration, or drying is again put into water. A suspended suspension may be used. Examples of the water include purified water such as ion exchange, distillation, and filtration.
　本発明に係る安定化工程において、このような懸濁液の初期ｐＨ（保存開始時のｐＨ）としては、５～７であることが好ましく、５～６であることがより好ましい。ｐＨが前記下限未満である場合には、前記三角平板状銀ナノ粒子の形状が変化しやすくなる傾向にあり、他方、前記上限を超える場合には、不純物が多く存在することを意味し、三角平板状銀ナノ粒子の形状変化を抑制する効果が低下する傾向にある。 In the stabilization step according to the present invention, the initial pH (pH at the start of storage) of such a suspension is preferably 5 to 7, and more preferably 5 to 6. When the pH is less than the lower limit, the shape of the triangular tabular silver nanoparticles tends to change, whereas when the upper limit is exceeded, it means that there are many impurities, There exists a tendency for the effect which suppresses the shape change of a flat silver nanoparticle to fall.
　さらに、前記銀ナノ粒子複合体を含有する懸濁液としては、水温２５℃における溶存酸素濃度が１～８ｍｇ－Ｏ／Ｌであることが好ましい。溶存酸素濃度が前記下限未満である場合には、溶存酸素による銀ナノ粒子の酸化に伴うｐＨの増加量が不十分且つ不安定となる傾向にあり、他方、前記上限を超えて酸素を含有させても、溶存酸素濃度は飽和濃度（水温２５℃において８．１１ｍｇ－Ｏ／Ｌ）以上にはならない。 Furthermore, the suspension containing the silver nanoparticle composite preferably has a dissolved oxygen concentration of 1 to 8 mg-O / L at a water temperature of 25 ° C. When the dissolved oxygen concentration is less than the lower limit, the amount of increase in pH associated with the oxidation of silver nanoparticles by dissolved oxygen tends to be insufficient and unstable, and on the other hand, oxygen is included exceeding the upper limit. However, the dissolved oxygen concentration does not exceed the saturation concentration (8.11 mg-O / L at a water temperature of 25 ° C.).
　本発明に係る安定化工程において、前記懸濁液における銀ナノ粒子複合体の濃度としては、３～２８ｍｇ／ｍｌであることが好ましく、７～１４ｍｇ／ｍｌであることがより好ましい。濃度が前記下限未満である場合には、三角平板状銀ナノ粒子の形状が変化して色が変化しやすくなる傾向にあり、他方、前記上限を超えて銀ナノ粒子複合体を含有させても、三角平板状銀ナノ粒子の形状変化の抑制効果はそれ以上向上せず、経済的に不利となる傾向にある。 In the stabilization step according to the present invention, the concentration of the silver nanoparticle composite in the suspension is preferably 3 to 28 mg / ml, and more preferably 7 to 14 mg / ml. When the concentration is less than the lower limit, the shape of the triangular tabular silver nanoparticles tends to change and the color tends to change, and on the other hand, the silver nanoparticle composite may be contained exceeding the upper limit. In addition, the effect of suppressing the shape change of the triangular tabular silver nanoparticles does not improve any more, and tends to be economically disadvantageous.
　前記保存条件において、保存時間が５０時間以上であると三角平板状銀ナノ粒子の形状変化の抑制効果が十分に向上し、前記形状変化の抑制効果は前記保存時間の経過に伴ってさらに向上するため、前記保存時間としては、３カ月間以上であることが好ましい。他方、三角平板状銀ナノ粒子の形状変化の抑制効果と経済的効果とのバランスの観点からは、前記保存時間としては５０時間～１ヶ月間であることが好ましい。また、保存環境は特に制限されないが、水が凍結しないという観点から、温度４～３０℃において静置することが好ましい。 In the storage conditions, if the storage time is 50 hours or more, the effect of suppressing the shape change of the triangular tabular silver nanoparticles is sufficiently improved, and the effect of suppressing the shape change is further improved as the storage time elapses. Therefore, the storage time is preferably 3 months or longer. On the other hand, from the viewpoint of the balance between the effect of suppressing the shape change of the triangular tabular silver nanoparticles and the economic effect, the storage time is preferably 50 hours to 1 month. Further, the storage environment is not particularly limited, but it is preferable to stand at a temperature of 4 to 30 ° C. from the viewpoint that water does not freeze.
　本発明の製造方法においては、前記安定化工程の後の前記懸濁液ををそのまま本発明の銀ナノ粒子複合体懸濁液とすることができ、必要に応じてｐＨを調整することにより、本発明のγ線感応センサ形成用組成物を得ることができる。また、前記懸濁液から遠心分離、濾過、乾燥等の方法で回収することにより、本発明の銀ナノ粒子複合体を得ることができる。 In the production method of the present invention, the suspension after the stabilizing step can be directly used as the silver nanoparticle composite suspension of the present invention, and by adjusting the pH as necessary, The composition for forming a γ-ray sensitive sensor of the present invention can be obtained. Further, the silver nanoparticle composite of the present invention can be obtained by recovering from the suspension by a method such as centrifugation, filtration, and drying.
　以下、実施例及び比較例に基づいて本発明をより具体的に説明するが、本発明は以下の実施例に限定されるものではない。なお、各実施例及び比較例における各測定及び評価はそれぞれ以下の方法により行った。 Hereinafter, the present invention will be described more specifically based on examples and comparative examples, but the present invention is not limited to the following examples. In addition, each measurement and evaluation in each Example and a comparative example were performed with the following method, respectively.
　＜吸光度測定＞
　銀ナノ粒子の調製により得られた各懸濁物４０μｌに純水９００μｌを加えて測定サンプルを調製し、各測定サンプルの吸光度を、吸光光度計（商品名：ＵＳＢ２０００、製造社：オーシャンオプティクス、測定波長：２００～１１００ｎｍ）を用いてそれぞれ測定した。また、銀ナノ粒子の調製により得られた上澄みについては、これをそのまま測定サンプルとし、上記と同様にして吸光度を測定した。 <Absorbance measurement>
A measurement sample is prepared by adding 900 μl of pure water to 40 μl of each suspension obtained by the preparation of silver nanoparticles, and the absorbance of each measurement sample is measured with an absorptiometer (trade name: USB2000, manufacturer: Ocean Optics, measurement). (Wavelength: 200 to 1100 nm). Moreover, about the supernatant obtained by preparation of silver nanoparticle, this was made into the measurement sample as it was, and the light absorbency was measured like the above.
　＜銀ナノ粒子複合体の測定＞
　（ｉ）走査型電子顕微鏡
　各実施例及び比較例において得られた銀ナノ粒子複合体懸濁液をピペットで試料台に移し、走査型電子顕微鏡（ＳＥＭ、商品名：ＪＳＭ－７５００Ｆ、製造社：日本電子株式会社）を用いて、金属酸化物粒子の平面上の任意の３０個以上の銀ナノ粒子の主平面の最長径及び厚さ、並びに、銀ナノ粒子が略三角形の主平面を有する場合にはその面積及び理想三角形の面積を測定し、これらの平均を求めた。前記略三角形面積は略三角形の面と平行な外表面の投影面積とし、前記理想三角形面積は、前記略三角形の投影図の直線部を延長して形成される三角形の面積とした。 <Measurement of silver nanoparticle composite>
(I) Scanning Electron Microscope The silver nanoparticle composite suspensions obtained in each Example and Comparative Example were pipetted to a sample stage, and a scanning electron microscope (SEM, trade name: JSM-7500F, manufacturer: JEOL Ltd.), the longest diameter and thickness of the main plane of any 30 or more silver nanoparticles on the plane of the metal oxide particles, and the silver nanoparticles have a substantially triangular main plane The area and the area of the ideal triangle were measured, and the average of these was obtained. The substantially triangular area is a projected area of an outer surface parallel to a substantially triangular surface, and the ideal triangular area is an area of a triangle formed by extending a straight line portion of the substantially triangular projection.
　測定した銀ナノ粒子のうち、最長径が２０～１２０ｎｍであり、厚さが５ｎｍ以上２０ｎｍ未満であり、主平面の形状が三角形又は略三角形であり、主平面が略三角形である場合には、次式：
　　角の欠損率（％）＝｛（理想三角形面積－対象角のみ欠損した略三角形面積）／理想三角形面積｝×１００
で求められるそれぞれの角の欠損率が１６．７％以下であるものを三角平板状銀ナノ粒子としてその個数を測定した。また、これにより測定された数値に基いて、測定した全銀ナノ粒子の個数に対する三角平板状銀ナノ粒子の個数（三角平板状銀ナノ粒子の含有比率）を次式：
　　三角平板状銀ナノ粒子の含有比率（％）＝（三角平板状銀ナノ粒子の個数／測定した銀ナノ粒子の個数）×１００
により計算することで求めた。 Among the measured silver nanoparticles, when the longest diameter is 20 to 120 nm, the thickness is 5 nm or more and less than 20 nm, the shape of the main plane is a triangle or a substantially triangle, and the main plane is a substantially triangle, The following formula:
Corner loss rate (%) = {(ideal triangle area−substantially triangular area where only the target corner is missing) / ideal triangle area} × 100
The number of each corner obtained in step 1 was 16.7% or less, and the number was measured as triangular tabular silver nanoparticles. Moreover, based on the numerical value measured by this, the number of triangular tabular silver nanoparticles (content ratio of triangular tabular silver nanoparticles) with respect to the number of all silver nanoparticles measured is expressed by the following formula:
Content ratio (%) of triangular tabular silver nanoparticles = (number of triangular tabular silver nanoparticles / number of measured silver nanoparticles) × 100
Calculated by
　（ｉｉ）透過型電子顕微鏡
　各実施例及び比較例において得られた銀ナノ粒子複合体懸濁液をピペットで試料台に移し、透過型電子顕微鏡（ＴＥＭ、商品名：ＪＥＭ－３０００Ｆ、製造社：日本電子株式会社）を用いて、金属酸化物粒子の平面接線方向からの観察を行った。 (Ii) Transmission Electron Microscope The silver nanoparticle composite suspensions obtained in each Example and Comparative Example were transferred to a sample stage with a pipette, and a transmission electron microscope (TEM, trade name: JEM-3000F, manufacturer: JEOL Ltd.) was used to observe the metal oxide particles from the plane tangential direction.
　＜複合体の安定性評価＞
　（ｉ）ハロゲン存在下での安定性評価
　先ず、各実施例及び比較例において得られた銀ナノ粒子複合体懸濁液１００μｌを１００ｍｍ２の濾紙に塗布し、上部に開口部のある積分球（商品名：ＩＳＰ－ＲＥＦ、製造社名：オーシャンオプティクス）にのせたガラスディッシュ中に設置した。次いで、前記ガラスディッシュ中に０．１７ｍｏｌ／Ｌ塩化ナトリウム水溶液４ｍｌを滴下し、分光器（商品名：ＵＳＢ２０００、製造社：オーシャンオプティクス）を用いて反射スペクトルを測定した。次いで、ガラスディッシュをそのまま大気中、室温（２５℃）において放置し、測定開始時から一定時間を経過するまでの反射スペクトルを測定した。測定した反射スペクトルから、ＣＩＥ表色系により色度（ｘ、ｙ）を算出し、ｘが０．３４になるまでの時間を退色時間（分）とした。なお、退色時間が長い程、銀ナノ粒子複合体の色の変化が少なく、銀ナノ粒子複合体における三角平板状銀ナノ粒子の形状変化が抑制されていることを示す。 <Stability evaluation of composite>
(I) Stability Evaluation in the Presence of Halogen First, 100 μl of the silver nanoparticle composite suspension obtained in each Example and Comparative Example was applied to 100 mm 2 filter paper, and an integrating sphere with an opening at the top ( (Product name: ISP-REF, manufacturer: Ocean Optics). Next, 4 ml of a 0.17 mol / L sodium chloride aqueous solution was dropped into the glass dish, and the reflection spectrum was measured using a spectroscope (trade name: USB2000, manufacturer: Ocean Optics). Next, the glass dish was left as it was in the atmosphere at room temperature (25 ° C.), and the reflection spectrum from the start of measurement until a fixed time elapsed was measured. Chromaticity (x, y) was calculated from the measured reflection spectrum by the CIE color system, and the time until x became 0.34 was defined as the fading time (minutes). In addition, it shows that the color change of a silver nanoparticle composite is so small that a fading time is long, and the shape change of the triangular tabular silver nanoparticle in a silver nanoparticle composite is suppressed.
　（ｉｉ）ハロゲン非存在下での経時安定性評価
　先ず、各実施例及び比較例において得られた銀ナノ粒子複合体懸濁液２ｍｌを蓋つきガラス瓶の中にいれて蓋をし、カラースキャナ（商品名：ＣａｎｏＳｃａｎ　Ｌｉｄｅ　２００、製造社名：キャノン株式会社）に設置して迷光を防ぐためにカバーをし、ガラス瓶の底面を走査することにより色情報を測定した（測定１）。次いで、ガラス瓶を一定時間室温（２５℃）に放置した後、再度色情報を測定した（測定２）。 (Ii) Evaluation of stability over time in the absence of halogen First, 2 ml of the silver nanoparticle composite suspension obtained in each of the examples and comparative examples was placed in a glass bottle with a lid, and the color scanner ( (Product name: CanoScan Lide 200, manufacturer name: Canon Inc.) was covered to prevent stray light, and the color information was measured by scanning the bottom surface of the glass bottle (Measurement 1). Next, the glass bottle was allowed to stand at room temperature (25 ° C.) for a certain time, and then color information was measured again (Measurement 2).
　測定した色情報から、ＣＩＥ表色系により色度（ｘ、ｙ）を算出し、測定１におけるｘの値と測定２におけるｘの値との変化量（ｘの変化量）を次式：
　ｘの変化量＝（測定２におけるｘの値－測定１におけるｘの値）／放置時間
により算出した。なお、ｘの変化量が小さい程、銀ナノ粒子複合体の色の変化が少なく、銀ナノ粒子複合体における三角平板状銀ナノ粒子の形状変化が抑制されていることを示す。 From the measured color information, chromaticity (x, y) is calculated by the CIE color system, and the amount of change (the amount of change in x) between the value of x in measurement 1 and the value of x in measurement 2 is expressed by the following formula:
x change amount = (x value in measurement 2−x value in measurement 1) / left time. In addition, it shows that the change of the color of a silver nanoparticle composite is so small that the variation | change_quantity of x is small, and the shape change of the triangular tabular silver nanoparticle in a silver nanoparticle composite is suppressed.
　＜銀ナノ粒子の調製＞
　各実施例及び比較例に用いた銀ナノ粒子は、それぞれ以下の方法により調製した。先ず、硝酸銀水溶液（硝酸銀：０．１ｍｍｏｌ／Ｌ）２００ｍｌにビス（ｐ－スルホナトフェニル）フェニルホスフィン二カリウム０．０２ｍｍｏｌを添加して溶解せしめ、さらに水素化ホウ素ナトリウム水溶液（ＮａＢＨ４：５０ｍｍｏｌ／Ｌ）２ｍｌを添加して１０分間撹拌した。この溶液に対し、大気中、室温（２５℃）において白色蛍光灯を７２時間照射し、黒紫色の銀ナノ粒子の懸濁液を得た。 <Preparation of silver nanoparticles>
Silver nanoparticles used in each example and comparative example were prepared by the following methods. First, 0.02 mmol of bis (p-sulfonatophenyl) phenylphosphine dipotassium was added and dissolved in 200 ml of an aqueous silver nitrate solution (silver nitrate: 0.1 mmol / L), and further an aqueous sodium borohydride solution (NaBH 4 : 50 mmol / L). 2 ml was added and stirred for 10 minutes. This solution was irradiated with a white fluorescent lamp for 72 hours in the atmosphere at room temperature (25 ° C.) to obtain a suspension of black-violet silver nanoparticles.
　次いで、得られた懸濁液を１６４０Ｇで６０分間遠心し、鮮やかな青色の銀ナノ粒子の懸濁物（懸濁物１）２ｍｌ程度及び上澄み（上澄み１）を得た。得られた上澄み１をさらに５０１０Ｇで６０分間遠心し、暗い青色の銀ナノ粒子の懸濁物（懸濁物２）及び黒紫色の上澄み（上澄み２）を得た。得られた懸濁物１～２及び上澄み２について吸光度を測定した。吸光度の測定結果を図１に示す。 Next, the obtained suspension was centrifuged at 1640 G for 60 minutes to obtain about 2 ml of a suspension (suspension 1) of bright blue silver nanoparticles and a supernatant (supernatant 1). The obtained supernatant 1 was further centrifuged at 5010 G for 60 minutes to obtain a suspension of dark blue silver nanoparticles (suspension 2) and a black purple supernatant (supernatant 2). Absorbance was measured for the resulting suspensions 1-2 and supernatant 2. The measurement results of absorbance are shown in FIG.
　図１に示すように、懸濁物１における銀ナノ粒子（銀ナノ粒子１）の吸光度は５８０～７５０ｎｍの範囲にあり、ピークは６００ｎｍであり、鮮やかな青色を呈していた。また、懸濁物２における銀ナノ粒子（銀ナノ粒子２）の吸光度は５００～７００ｎｍの範囲にあり、ピークは５６０ｎｍであり、暗い青色を呈していた。さらに、上澄み２における銀ナノ粒子（銀ナノ粒子３）の吸光度は４００～６５０ｎｍの範囲にあり、ピークは５２０ｎｍであり、黒に近い紫色を呈していた。なお、前記懸濁物１～２、上澄み２における銀ナノ粒子の含有量はそれぞれ３０質量％、２０質量％、４５質量％であり、銀ナノ粒子１～３における三角平板状銀ナノ粒子の含有量はそれぞれ７９質量％、７６質量％、２８質量％であった。 As shown in FIG. 1, the absorbance of the silver nanoparticles (silver nanoparticles 1) in the suspension 1 was in the range of 580 to 750 nm, the peak was 600 nm, and a bright blue color was exhibited. Further, the absorbance of the silver nanoparticles (silver nanoparticles 2) in the suspension 2 was in the range of 500 to 700 nm, the peak was 560 nm, and a dark blue color was exhibited. Further, the absorbance of the silver nanoparticles (silver nanoparticles 3) in the supernatant 2 was in the range of 400 to 650 nm, the peak was 520 nm, and a purple color close to black was exhibited. In addition, the content of silver nanoparticles in the suspensions 1 and 2 and the supernatant 2 is 30% by mass, 20% by mass, and 45% by mass, respectively, and the inclusion of triangular tabular silver nanoparticles in the silver nanoparticles 1 to 3 The amounts were 79% by mass, 76% by mass and 28% by mass, respectively.
　＜金属酸化物粒子＞
　各実施例及び比較例においては、以下の市販の金属酸化物粒子を用いた。
金属酸化物粒子１：α－アルミナ（商品名：セラフ、製造社名：キンセイマティック社、平面の平均投影面積：３．１４μｍ２（平面の平均直径：２μｍ）、平板状（アスペクト比：５０（２μｍ／４０ｎｍ）、ｐＨ５．６におけるゼータ電位：４２ｍＶ）
金属酸化物粒子２：α－アルミナ（商品名：α－アルミナ１－２μ、製造社名：和光純薬工業株式会社、平面の平均投影面積：０．７８５μｍ２（平面の平均直径：１μｍ）、球状、ｐＨ５．６におけるゼータ電位：４２ｍＶ）。 <Metal oxide particles>
In each example and comparative example, the following commercially available metal oxide particles were used.
Metal oxide particles 1: α-alumina (trade name: Seraph, manufacturer: Kinseimatic, plane average projected area: 3.14 μm 2 (plane average diameter: 2 μm), flat plate (aspect ratio: 50 (2 μm) / 40 nm), zeta potential at pH 5.6: 42 mV)
Metal oxide particles 2: α-alumina (trade name: α-alumina 1-2 μ, manufacturer: Wako Pure Chemical Industries, Ltd., average projected area of plane: 0.785 μm 2 (average diameter of plane: 1 μm), spherical Zeta potential at pH 5.6: 42 mV).
　＜複合体の製造＞
　（実施例１）
　大気中、室温（２５℃）において、２ｍｌの銀ナノ粒子１を含有する懸濁物１（銀ナノ粒子１：３．２ｍｇ）を金属酸化物粒子１の水懸濁液（１ｍｇ／ｍｌ、ｐＨ６）２５ｍｌに撹拌しながら１分間かけて添加（銀ナノ粒子１の質量：金属酸化物１の質量＝１２．８：１００）して上澄みを除去し、鮮やかな青色の銀ナノ粒子複合体を含有する銀ナノ粒子複合体懸濁液（銀ナノ粒子複合体濃度：１４ｍｇ／ｍｌ）を２ｍｌ得た。なお、各水懸濁液の調製には、ｐＨ６、水温２５℃における溶存酸素濃度４ｍｇ－Ｏ／Ｌの超純水を用いた。 <Manufacture of composite>
(Example 1)
In air, at room temperature (25 ° C.), a suspension 1 (silver nanoparticles 1: 3.2 mg) containing 2 ml of silver nanoparticles 1 was dissolved in an aqueous suspension of metal oxide particles 1 (1 mg / ml, pH 6). ) Add to 25 ml with stirring over 1 minute (mass of silver nanoparticles 1: mass of metal oxide 1 = 12.8: 100) to remove the supernatant and contain a bright blue silver nanoparticle composite 2 ml of a silver nanoparticle composite suspension (silver nanoparticle composite concentration: 14 mg / ml) was obtained. Each water suspension was prepared using ultrapure water having a dissolved oxygen concentration of 4 mg-O / L at pH 6 and a water temperature of 25 ° C.
　（実施例２～５）
　先ず、実施例１と同様にして、鮮やかな青色の銀ナノ粒子複合体を含有する銀ナノ粒子複合体懸濁液を得た。次いで、得られた銀ナノ粒子複合体懸濁液をそのまま蓋つきのガラス瓶に入れて蓋をし、５０時間（実施例２）、１６日間（実施例３）、２５日間（実施例４）及び３５日間（実施例５）それぞれ室温（２５℃）に静置して保存し、銀ナノ粒子複合体懸濁液をそれぞれ得た。 (Examples 2 to 5)
First, in the same manner as in Example 1, a silver nanoparticle composite suspension containing a bright blue silver nanoparticle composite was obtained. Next, the obtained silver nanoparticle composite suspension is put in a glass bottle with a lid as it is, and the lid is closed. 50 hours (Example 2), 16 days (Example 3), 25 days (Example 4) and 35 Each day (Example 5) was stored at room temperature (25 ° C.) to obtain silver nanoparticle composite suspensions.
　（実施例６）
　酸素をバブリングして供給しながら銀ナノ粒子１と金属酸化物粒子１とを撹拌したこと以外は実施例１と同様にして、鮮やかな青色の銀ナノ粒子複合体を含有する銀ナノ粒子複合体懸濁液を得た。 (Example 6)
A silver nanoparticle composite containing a bright blue silver nanoparticle composite in the same manner as in Example 1 except that the silver nanoparticles 1 and the metal oxide particles 1 were stirred while bubbling and supplying oxygen. A suspension was obtained.
　（実施例７～１０）
　銀ナノ粒子１と金属酸化物１との質量比（銀ナノ粒子１の質量：金属酸化物１の質量）をそれぞれ１．６：１００（実施例７）、３．２：１００（実施例８）、６．４：１００（実施例９）、２６．５：１００（実施例１０）としたこと以外は実施例１と同様にして、鮮やかな青色の銀ナノ粒子複合体を含有する銀ナノ粒子複合体懸濁液をそれぞれ得た。 (Examples 7 to 10)
The mass ratio of silver nanoparticles 1 to metal oxide 1 (the mass of silver nanoparticles 1: the mass of metal oxide 1) was 1.6: 100 (Example 7) and 3.2: 100 (Example 8), respectively. ), 6.4: 100 (Example 9), 26.5: 100 (Example 10), and the same manner as in Example 1 except that the silver nanoparticle containing a bright blue silver nanoparticle composite is contained. Each of the particle composite suspensions was obtained.
　（比較例１）
　銀ナノ粒子１を含有する懸濁物１に水を添加して１．６ｍｇ／ｍｌの銀ナノ粒子の水懸濁液を得た。 (Comparative Example 1)
Water was added to the suspension 1 containing the silver nanoparticles 1 to obtain an aqueous suspension of 1.6 mg / ml silver nanoparticles.
　（比較例２）
　銀ナノ粒子１を含有する懸濁物１に代えて銀ナノ粒子２を含有する懸濁物２（銀ナノ粒子２：２ｍｇ）を用いたこと以外は実施例１と同様にして、暗青色の銀ナノ粒子複合体を含有する銀ナノ粒子複合体懸濁液を得た。 (Comparative Example 2)
In the same manner as in Example 1 except that the suspension 2 containing silver nanoparticles 2 (silver nanoparticles 2: 2 mg) was used instead of the suspension 1 containing silver nanoparticles 1, a dark blue A silver nanoparticle composite suspension containing the silver nanoparticle composite was obtained.
　（比較例３）
　銀ナノ粒子１を含有する懸濁液１に代えて銀ナノ粒子３を含有する懸濁液（上澄み２、銀ナノ粒子３：４．９ｍｇ）を用いたこと以外は実施例１と同様にして、黒紫色の銀ナノ粒子複合体を含有する銀ナノ粒子複合体懸濁液を得た。 (Comparative Example 3)
It replaced with the suspension liquid 1 containing the silver nanoparticle 1 and carried out similarly to Example 1 except having used the suspension liquid (supernatant 2, silver nanoparticle 3: 4.9 mg) containing the silver nanoparticle 3. A silver nanoparticle composite suspension containing a black purple silver nanoparticle composite was obtained.
　（比較例４）
　金属酸化物粒子１に代えて金属酸化物粒子２を用いたこと以外は実施例１と同様にして、赤紫色の銀ナノ粒子複合体を含有する銀ナノ粒子複合体懸濁液を得た。 (Comparative Example 4)
A silver nanoparticle composite suspension containing a reddish purple silver nanoparticle composite was obtained in the same manner as in Example 1 except that the metal oxide particles 2 were used in place of the metal oxide particles 1.
　（比較例５）
　金属酸化物粒子１の水懸濁液に水酸化ナトリウムを加えてｐＨを１３としたこと以外は実施例１と同様にして銀ナノ粒子複合体懸濁液を得ようとしたが、銀ナノ粒子１が退色し目視では透明になってしまった。 (Comparative Example 5)
A silver nanoparticle composite suspension was obtained in the same manner as in Example 1 except that sodium hydroxide was added to the aqueous suspension of metal oxide particles 1 to adjust the pH to 13. 1 faded and became visually transparent.
　（比較例６）
　金属酸化物粒子１の水懸濁液に塩酸を加えてｐＨを４以下としたこと以外は実施例１と同様にして銀ナノ粒子複合体懸濁液を得ようとしたが、銀ナノ粒子１を金属酸化物粒子１に吸着せしめることができず、また、銀ナノ粒子１が紫色に変色してしまった。 (Comparative Example 6)
A silver nanoparticle composite suspension was obtained in the same manner as in Example 1 except that hydrochloric acid was added to the aqueous suspension of metal oxide particles 1 to adjust the pH to 4 or less. Could not be adsorbed on the metal oxide particles 1, and the silver nanoparticles 1 had turned purple.
　各実施例及び比較例において得られた銀ナノ粒子複合体懸濁液又は懸濁液について、銀ナノ粒子複合体の測定及び複合体の安定性評価をそれぞれ行った。 The silver nanoparticle composite suspensions or suspensions obtained in each Example and Comparative Example were measured for the silver nanoparticle composite and evaluated for the stability of the composite.
　（実施例１、比較例１～３で得られた複合体の測定及び評価）
　得られてすぐの銀ナノ粒子複合体懸濁液を用いて、銀ナノ粒子と金属酸化物粒子との吸着直後の銀ナノ粒子複合体の測定、及びハロゲン存在下での安定性評価を行った。実施例１及び比較例２～３における銀ナノ粒子複合体の測定結果を表１に示し、各走査型電子顕微鏡写真（ＳＥＭ像）をそれぞれ図２Ａ～図４Ｂに示し、実施例１における銀ナノ粒子複合体の透過型電子顕微鏡写真（ＴＥＭ像）を図５Ａ及び図５Ｂに示す。なお、各ＳＥＭ像において、白色に見える粒子は銀ナノ粒子であり、灰色にみえる平板は金属酸化物粒子である。また、図５ＡのＴＥＭ像において、中央に大きく見える平板が金属酸化物粒子であり、その表面に吸着している粒子が銀ナノ粒子である。 (Measurement and evaluation of the composites obtained in Example 1 and Comparative Examples 1 to 3)
Using the obtained silver nanoparticle composite suspension, we measured the silver nanoparticle composite immediately after adsorption of silver nanoparticles and metal oxide particles, and evaluated the stability in the presence of halogen. . The measurement results of the silver nanoparticle composites in Example 1 and Comparative Examples 2 to 3 are shown in Table 1, and scanning electron micrographs (SEM images) are shown in FIGS. 2A to 4B, respectively. Transmission electron micrographs (TEM images) of the particle composite are shown in FIGS. 5A and 5B. In each SEM image, particles that appear white are silver nanoparticles, and flat plates that appear gray are metal oxide particles. In the TEM image of FIG. 5A, the flat plate that appears large in the center is metal oxide particles, and the particles adsorbed on the surface are silver nanoparticles.
　さらに、ハロゲン存在下での安定性評価において、実施例１及び比較例２～３のＣＩＥ表色系におけるｘの値と測定開始時からの経過時間との関係を示すグラフを図６に示す。図６より、実施例１の退色時間は３０分、比較例２の退色時間は１５分であった。なお、ハロゲン存在下での安定性評価では、比較例１は塩化ナトリウム水溶液を滴下して１０秒以内に色が青から紫色に変化した。また、比較例３は銀ナノ粒子複合体懸濁液を得た時から既にｘの値が０．３４を超えていたため、退色時間は算出できなかった。 Furthermore, in the stability evaluation in the presence of halogen, a graph showing the relationship between the value of x in the CIE color system of Example 1 and Comparative Examples 2 to 3 and the elapsed time from the start of measurement is shown in FIG. From FIG. 6, the fading time of Example 1 was 30 minutes, and the fading time of Comparative Example 2 was 15 minutes. In addition, in the stability evaluation in the presence of halogen, in Comparative Example 1, the color changed from blue to purple within 10 seconds after dropping the sodium chloride aqueous solution. In Comparative Example 3, since the value of x had already exceeded 0.34 since the silver nanoparticle composite suspension was obtained, the fading time could not be calculated.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１に示した結果、図２Ａ及び図２Ｂに示したＳＥＭ像から明らかなように、本発明の銀ナノ粒子複合体においては本発明に係る三角平板状銀ナノ粒子の含有比率が十分に高いことが確認された。さらに、図５Ａ及び図５Ｂに示したＴＥＭ像からも、平板状銀ナノ粒子の厚みは５－７ｎｍの範囲にあることが確認された。また、金属酸化物粒子とその表面に吸着している銀ナノ粒子との間には１ｎｍ未満のわずかな空隙（Ｇａｐ）があることが確認された。さらに、ハロゲンを添加したときの退色時間が十分に長いことから、本発明の銀ナノ粒子複合体においてはハロゲンの存在下であっても三角平板状銀ナノ粒子の形状変化が十分に抑制されていることが確認された。他方、表１に示した結果及び図３Ａ～図４Ｂに示したＳＥＭ像から明らかなように、比較例２～３において得られた銀ナノ粒子複合体においては、銀ナノ粒子の最長径が小さいものが多く含まれており、また、三角平板状銀ナノ粒子の含有比率は低いものであった。また、比較例２ではｘの値の変化量が大きく、退色時間が短いことから、ハロゲンの存在下では特に三角平板状銀ナノ粒子の形状変化を抑制できないことが確認された。 As is clear from the SEM images shown in FIG. 2A and FIG. 2B as a result shown in Table 1, the content ratio of the triangular tabular silver nanoparticles according to the present invention is sufficiently high in the silver nanoparticle composite of the present invention. It was confirmed. Furthermore, from the TEM images shown in FIGS. 5A and 5B, it was confirmed that the thickness of the tabular silver nanoparticles was in the range of 5-7 nm. Moreover, it was confirmed that there is a slight gap (Gap) of less than 1 nm between the metal oxide particles and the silver nanoparticles adsorbed on the surface. Furthermore, since the fading time when adding halogen is sufficiently long, the shape change of the triangular tabular silver nanoparticles is sufficiently suppressed even in the presence of halogen in the silver nanoparticle composite of the present invention. It was confirmed that On the other hand, as is clear from the results shown in Table 1 and the SEM images shown in FIGS. 3A to 4B, in the silver nanoparticle composites obtained in Comparative Examples 2 to 3, the longest diameter of the silver nanoparticles is small. In addition, the content of the triangular tabular silver nanoparticles was low. In Comparative Example 2, since the amount of change in the value of x was large and the fading time was short, it was confirmed that the shape change of the triangular tabular silver nanoparticles could not be suppressed particularly in the presence of halogen.
　（実施例１、比較例４で得られた複合体の測定及び評価）
　得られてすぐ（銀ナノ粒子と金属酸化物粒子との吸着から１２０分後）の銀ナノ粒子複合体懸濁液を用いて、ハロゲン非存在下での経時安定性評価を行った。評価における放置時間は１週間とした。ハロゲン非存在下での経時安定性評価において、実施例１におけるｘの変化量は０．０１１０６／７日間であり、比較例４におけるｘの変化量は０．０４１９６／７日間であった。また、１週間放置後（銀ナノ粒子と金属酸化物粒子との吸着から１週間経過後）の銀ナノ粒子複合体懸濁液について、銀ナノ粒子複合体の測定を行った。測定結果を実施例１についての吸着直後の測定結果と共に表２に示し、実施例１及び比較例４の銀ナノ粒子と金属酸化物粒子との吸着から１週間経過後の走査型電子顕微鏡写真（ＳＥＭ像）をそれぞれ図７Ａ～図８Ｂに示す。 (Measurement and evaluation of the composite obtained in Example 1 and Comparative Example 4)
Using the silver nanoparticle composite suspension immediately after it was obtained (120 minutes after the adsorption of silver nanoparticles and metal oxide particles), stability with time was evaluated in the absence of halogen. The standing time in the evaluation was 1 week. In the evaluation of stability over time in the absence of halogen, the amount of change in x in Example 1 was 0.01106 / 7 days, and the amount of change in x in Comparative Example 4 was 0.04196 / 7 days. In addition, the silver nanoparticle composite was measured for the silver nanoparticle composite suspension after standing for one week (after one week from the adsorption of silver nanoparticles and metal oxide particles). The measurement results are shown in Table 2 together with the measurement results immediately after adsorption for Example 1, and a scanning electron micrograph after one week has elapsed from the adsorption of the silver nanoparticles and metal oxide particles of Example 1 and Comparative Example 4 ( SEM images) are shown in FIGS. 7A to 8B, respectively.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　表２及び図７Ａ～図８Ｂに示したＳＥＭ像から明らかなように、本発明の銀ナノ粒子複合体は銀ナノ粒子と金属酸化物粒子とを吸着させてから１週間経過しても銀ナノ粒子の最長径は十分に長いままであって、三角平板状銀ナノ粒子の含有比率も十分に高く維持されており、さらに、本発明の銀ナノ粒子複合体はｘの変化量も小さく、三角平板状銀ナノ粒子の形状変化が十分に抑制されていることが確認された。他方、比較例４で得られた銀ナノ粒子複合体は銀ナノ粒子と金属酸化物粒子とを吸着させてから１週間経過後には銀ナノ粒子の最長径は約１７％短く、三角平板状銀ナノ粒子の含有比率が低くなっており、また、ｘの変化量も大きく、三角平板状銀ナノ粒子の形状変化が十分に抑制されないことが確認された。 As is apparent from the SEM images shown in Table 2 and FIGS. 7A to 8B, the silver nanoparticle composite of the present invention can be obtained even after one week has passed since the silver nanoparticles and the metal oxide particles are adsorbed. The longest diameter of the particles remains sufficiently long, the content ratio of the triangular tabular silver nanoparticles is maintained sufficiently high, and the silver nanoparticle composite of the present invention has a small change amount of x. It was confirmed that the shape change of the tabular silver nanoparticles was sufficiently suppressed. On the other hand, the silver nanoparticle composite obtained in Comparative Example 4 has a longest diameter of about 17% shorter than one week after the silver nanoparticles and the metal oxide particles are adsorbed. The content ratio of the nanoparticles was low, and the amount of change in x was large, confirming that the shape change of the triangular tabular silver nanoparticles was not sufficiently suppressed.
　（実施例２～５で得られた複合体の評価）
　各保存時間経過後において、ハロゲン存在下での安定性評価を行った。ＣＩＥ表色系におけるｘの値と測定開始時からの経過時間との関係を示すグラフを図９に、退色時間と保存時間との関係を示すグラフを図１０にそれぞれ示す。図９～１０に示した結果から明らかなように、本発明の銀ナノ粒子複合体の製造方法において銀ナノ粒子と金属酸化物粒子とを吸着させた後の保存時間が長い程、ハロゲンを添加したときの退色時間がより長くなることが確認された。 (Evaluation of the composites obtained in Examples 2 to 5)
After each storage time, stability evaluation in the presence of halogen was performed. A graph showing the relationship between the value of x in the CIE color system and the elapsed time from the start of measurement is shown in FIG. 9, and a graph showing the relationship between the fading time and the storage time is shown in FIG. As is apparent from the results shown in FIGS. 9 to 10, in the method for producing a silver nanoparticle composite of the present invention, the longer the storage time after adsorbing silver nanoparticles and metal oxide particles, the more halogen is added. It was confirmed that the fading time was longer.
　（実施例６で得られた複合体の評価）
　得られてすぐ（銀ナノ粒子と金属酸化物粒子との吸着から６０分後）の銀ナノ粒子複合体懸濁液を用いて、ハロゲン存在下での安定性評価を行ったが、結果は実施例１における結果と差がないものであった。この結果から、本発明の銀ナノ粒子複合体の製造方法において銀ナノ粒子と金属酸化物粒子とを吸着させるときにおける溶存酸素濃度は銀ナノ粒子複合体の安定性に影響を与えないことが確認された。 (Evaluation of the composite obtained in Example 6)
Stability evaluation in the presence of halogen was performed using a silver nanoparticle composite suspension immediately after it was obtained (60 minutes after adsorption of silver nanoparticles and metal oxide particles). There was no difference from the result in Example 1. From this result, it was confirmed that the dissolved oxygen concentration when adsorbing silver nanoparticles and metal oxide particles in the method for producing a silver nanoparticle composite of the present invention does not affect the stability of the silver nanoparticle composite. It was done.
　（実施例１、７～１０で得られた複合体の評価）
　得られてすぐ（銀ナノ粒子と金属酸化物粒子との吸着から６０分後）の銀ナノ粒子複合体懸濁液を用いて、ハロゲン非存在下での経時安定性評価を行った。評価における放置時間は４５６時間（１９日間）とした。ハロゲン非存在下での経時安定性評価において、測定１の時（銀ナノ粒子と金属酸化物粒子との吸着から６０分後）及び測定２の時（銀ナノ粒子と金属酸化物粒子との吸着から４５６時間後）の状態を示す写真をそれぞれ図１１及び図１２に示す。図１１及び図１２に示した結果から、本発明の銀ナノ粒子複合体においては、銀ナノ粒子と金属酸化物との質量比（銀ナノ粒子の質量：金属酸化物の質量）が６．４：１００～１２．８：１００（三角平板状銀ナノ粒子の質量：金属酸化物の質量＝５：１００～１０：１００）であるときに、より三角平板状銀ナノ粒子の形状を安定して維持することができる傾向にあることが確認された。 (Evaluation of the composites obtained in Examples 1 and 7 to 10)
Using the silver nanoparticle composite suspension immediately after it was obtained (60 minutes after the adsorption of silver nanoparticles and metal oxide particles), the stability over time in the absence of halogen was evaluated. The standing time in the evaluation was 456 hours (19 days). In the evaluation of stability over time in the absence of halogen, measurement 1 (60 minutes after adsorption of silver nanoparticles and metal oxide particles) and measurement 2 (adsorption of silver nanoparticles and metal oxide particles) 11 and 12 respectively show photographs showing the state after 456 hours). From the results shown in FIGS. 11 and 12, in the silver nanoparticle composite of the present invention, the mass ratio of silver nanoparticles to metal oxide (the mass of silver nanoparticles: the mass of metal oxide) is 6.4. : 100 to 12.8: 100 (mass of triangular tabular silver nanoparticles: mass of metal oxide = 5: 100 to 10: 100), the shape of triangular tabular silver nanoparticles is more stable. It was confirmed that it tends to be maintained.
　＜組成物の製造＞
　（実施例１１）
　実施例１で得られた銀ナノ粒子複合体懸濁液に０．１Ｍリン酸緩衝液（リン酸二水素ナトリウムとリン酸水素ナトリウムの混合液）を添加してｐＨを５．８に調整し、鮮やかな青色の組成物（銀ナノ粒子複合体濃度：１０ｍｇ／ｍｌ）を得た。 <Production of composition>
(Example 11)
To the silver nanoparticle composite suspension obtained in Example 1, 0.1 M phosphate buffer (mixed solution of sodium dihydrogen phosphate and sodium hydrogen phosphate) was added to adjust the pH to 5.8. A bright blue composition (silver nanoparticle composite concentration: 10 mg / ml) was obtained.
　（実施例１２～１６、比較例７）
　組成物のｐＨを順に６．９（実施例１２）、７．８（実施例１３）、６．６（実施例１４）、７．３（実施例１５）、７．９（実施例１６）、９．７（比較例７）としたこと以外は実施例１１と同様にしてそれぞれ組成物を得た。 (Examples 12 to 16, Comparative Example 7)
The pH of the composition was 6.9 (Example 12), 7.8 (Example 13), 6.6 (Example 14), 7.3 (Example 15), 7.9 (Example 16) in this order. , 9.7 (Comparative Example 7), except that the composition was obtained in the same manner as in Example 11.
　γ線源としてコバルト６０を用い、温度２５度において、実施例１１～１３で得られた組成物に対して３００Ｇｙ（１．１７ＭｅＶ、１．３３ＭｅＶ）のγ線を、実施例１４～１６、比較例７で得られた組成物に対して３０００Ｇｙ（１．１７ＭｅＶ、１．３３ＭｅＶ）のγ線を照射してγ線に対する感応性の評価を行った。 Using cobalt 60 as the γ-ray source and comparing the compositions obtained in Examples 11 to 13 with 300 Gy (1.17 MeV, 1.33 MeV) γ-rays at a temperature of 25 degrees, Examples 14 to 16 were compared. The composition obtained in Example 7 was irradiated with 3000 Gy (1.17 MeV, 1.33 MeV) of γ rays to evaluate the sensitivity to γ rays.
　実施例１１～１３で得られた組成物に対して３００Ｇｙのγ線を照射する前及び後の状態を示す写真をそれぞれ図１３及び図１４に示し、実施例１４～１６、比較例７で得られた組成物に対して３０００Ｇｙのγ線を照射した前及び後の状態を示す写真をそれぞれ図１６及び図１７に示す。また、前記γ線を照射する前後において、前記ハロゲン非存在下での経時安定性評価と同様にして色情報を測定して得られたＣＩＥ色度図を図１５（実施例１１～１３、３００Ｇｙ）及び図１８（実施例１４～１６、比較例７；３０００Ｇｙ）にそれぞれ示す。図１５において、実施例１１～１３はγ線の照射により色度ｘが１０～１５％程度増加し、色度ｙが３～４％程度減少したことが確認された。また、図１８において、実施例１４～１６はγ線の照射により色度ｘが５０％程度増加し、色度ｙが１５％程度減少したことが確認された。 The photographs showing the states obtained before and after irradiating the composition obtained in Examples 11 to 13 with 300 Gy of γ rays are shown in FIGS. 13 and 14, respectively, and obtained in Examples 14 to 16 and Comparative Example 7. The photograph which shows the state before and after irradiating 3000 Gy gamma rays with respect to the obtained composition is shown in FIG.16 and FIG.17, respectively. Further, CIE chromaticity diagrams obtained by measuring color information in the same manner as in the evaluation of stability over time in the absence of halogen before and after the irradiation of γ rays are shown in FIG. 15 (Examples 11 to 13, 300 Gy). ) And FIG. 18 (Examples 14 to 16, Comparative Example 7; 3000 Gy), respectively. In FIG. 15, in Examples 11 to 13, it was confirmed that the chromaticity x increased by about 10 to 15% and the chromaticity y decreased by about 3 to 4% by γ-ray irradiation. In FIG. 18, it was confirmed that in Examples 14 to 16, the chromaticity x increased by about 50% and the chromaticity y decreased by about 15% by γ-ray irradiation.
　図１３～図１８に示した結果から明らかなように、本発明の組成物はγ線が照射されることにより鮮やかな青色から赤色へと変色したことに対し、比較例７においては変色が起こらないことが確認された。なお、本発明の組成物は自然光の当たる環境にそのまま放置しても変退色は起こらず、紫外線に対しては安定であることが確認された。 As is apparent from the results shown in FIGS. 13 to 18, the composition of the present invention changed its color from vivid blue to red when irradiated with γ rays, whereas in Comparative Example 7, the color change occurred. Not confirmed. The composition of the present invention was confirmed to be stable against ultraviolet rays without causing discoloration even when left in an environment exposed to natural light.
　以上説明したように、本発明によれば、三角平板状銀ナノ粒子の含有比率が高く、ハロゲンの存在下でも三角平板状銀ナノ粒子の形状変化が十分に抑制される銀ナノ粒子複合体、銀ナノ粒子複合体懸濁液及び銀ナノ粒子複合体の製造方法を提供することが可能となる。従って、本発明の銀ナノ粒子複合体及び銀ナノ粒子複合体懸濁液は、顔料、バイオセンサ等の色材として非常に有用である。 As described above, according to the present invention, a silver nanoparticle composite in which the content ratio of triangular tabular silver nanoparticles is high and the shape change of triangular tabular silver nanoparticles is sufficiently suppressed even in the presence of halogen, It becomes possible to provide a silver nanoparticle composite suspension and a method for producing a silver nanoparticle composite. Therefore, the silver nanoparticle composite and the silver nanoparticle composite suspension of the present invention are very useful as coloring materials for pigments, biosensors and the like.
　また、本発明によれば、前記銀ナノ粒子複合体を用いることにより、紫外線に対して十分に安定であるγ線感応センサ形成用組成物及びγ線感応センサを提供することが可能となる。 In addition, according to the present invention, by using the silver nanoparticle composite, it is possible to provide a composition for forming a γ-ray sensitive sensor and a γ-ray sensitive sensor that are sufficiently stable against ultraviolet rays.

Claims (13)

  1. 　主平面の形状が三角形又は略三角形であり、前記主平面の初期平均最長径が２０～１２０ｎｍであり且つ初期平均厚さが５ｎｍ以上２０ｎｍ未満である複数の三角平板状銀ナノ粒子が、平板状金属酸化物粒子の平面上に吸着してなる銀ナノ粒子複合体であり、
    　前記平板状金属酸化物粒子が、ｐＨ５～７におけるゼータ電位が正の金属酸化物からなり、且つ、前記平面として前記三角平板状銀ナノ粒子の初期平均最長径の１６．７～５００倍の平均直径を有する平面を有するものであり、
    　前記平面上に吸着されている銀ナノ粒子の全個数のうちの７５％以上が、主平面の形状が三角形又は略三角形であり、前記主平面の最長径が２０～１２０ｎｍであり且つ厚さが５ｎｍ以上２０ｎｍ未満であるという条件を満たす形状を維持している三角平板状銀ナノ粒子である銀ナノ粒子複合体。     A plurality of triangular tabular silver nanoparticles having a main plane shape of a triangle or a substantially triangular shape, an initial average longest diameter of the main plane of 20 to 120 nm, and an initial average thickness of 5 nm or more and less than 20 nm are tabular. It is a silver nanoparticle composite formed by adsorbing on the plane of metal oxide particles,
    The tabular metal oxide particles are made of a metal oxide having a positive zeta potential at a pH of 5 to 7, and have an average of 16.7 to 500 times the initial average longest diameter of the triangular tabular silver nanoparticles as the plane. Having a plane with a diameter,
    More than 75% of the total number of silver nanoparticles adsorbed on the plane has a main plane shape of a triangle or a substantially triangle, the main plane has a longest diameter of 20 to 120 nm and a thickness of A silver nanoparticle composite that is a triangular tabular silver nanoparticle that maintains a shape that satisfies the condition of 5 nm or more and less than 20 nm.
  2. 　前記平板状金属酸化物粒子のアスペクト比（平面の平均直径／平均厚さ）が１０～１００である請求項１に記載の銀ナノ粒子複合体。 The silver nanoparticle composite according to claim 1, wherein the flat metal oxide particles have an aspect ratio (average diameter of plane / average thickness) of 10 to 100.
  3. 　前記平板状金属酸化物粒子がα－アルミナ、γ－アルミナ、チタニア及び酸化亜鉛からなる群から選択される少なくともいずれか１種からなる、請求項１又は２に記載の銀ナノ粒子複合体。 The silver nanoparticle composite according to claim 1 or 2, wherein the plate-like metal oxide particles comprise at least one selected from the group consisting of α-alumina, γ-alumina, titania and zinc oxide.
  4. 　前記平板状金属酸化物粒子の平面上において、前記平面上に吸着されている前記三角平板状銀ナノ粒子の占有面積率が１～１００％である請求項１～３のうちのいずれか一項に記載の銀ナノ粒子複合体。 The occupation area ratio of the triangular tabular silver nanoparticles adsorbed on the flat surface of the flat metal oxide particles is 1 to 100%. A silver nanoparticle composite according to 1.
  5. 　前記三角平板状銀ナノ粒子と前記平板状金属酸化物粒子との質量比（三角平板状銀ナノ粒子の質量：平板状金属酸化物粒子の質量）が１：１００～３０：１００である請求項１～４のうちのいずれか一項に記載の銀ナノ粒子複合体。 The mass ratio of the triangular tabular silver nanoparticles to the tabular metal oxide particles (the mass of the triangular tabular silver nanoparticles: the mass of the tabular metal oxide particles) is 1: 100 to 30: 100. The silver nanoparticle composite according to any one of 1 to 4.
  6. 　γ線が照射されることにより変退色するγ線感応材料として用いられる請求項１～５のうちのいずれか一項に記載の銀ナノ粒子複合体。 The silver nanoparticle composite according to any one of claims 1 to 5, which is used as a γ-ray sensitive material that changes color and fades when irradiated with γ-rays.
  7. 　請求項１～６のうちのいずれか一項に記載の銀ナノ粒子複合体が水溶液中に懸濁されている銀ナノ粒子複合体懸濁液。 A silver nanoparticle composite suspension in which the silver nanoparticle composite according to any one of claims 1 to 6 is suspended in an aqueous solution.
  8. 　ｐＨが前記平板状金属酸化物粒子の等電点以上である請求項７に記載の銀ナノ粒子複合体懸濁液。 The silver nanoparticle composite suspension according to claim 7, wherein the pH is equal to or higher than the isoelectric point of the flat metal oxide particles.
  9. 　水及びγ線感応材料を含有するγ線感応センサ形成用組成物であって、ｐＨが６以上９．７未満であり、前記γ線感応材料として請求項６に記載の銀ナノ粒子複合体を用いるγ線感応センサ形成用組成物。 A composition for forming a γ-ray sensitive sensor comprising water and a γ-ray sensitive material, wherein the pH is 6 or more and less than 9.7, and the silver nanoparticle composite according to claim 6 is used as the γ-ray sensitive material. A composition for forming a γ-ray sensitive sensor to be used.
  10. 　請求項９に記載のγ線感応センサ形成用組成物により形成されたγ線感応センサ。 A gamma ray sensitive sensor formed of the composition for gamma ray sensitive sensor formation according to claim 9.
  11. 　主平面の形状が三角形又は略三角形であり、前記主平面の初期平均最長径が２０～１２０ｎｍであり且つ初期平均厚さが５ｎｍ以上２０ｎｍ未満である複数の三角平板状銀ナノ粒子と、
    　ｐＨ５～７におけるゼータ電位が正の金属酸化物からなり、且つ、平面として前記三角平板状銀ナノ粒子の初期平均最長径の１６．７～５００倍の平均直径を有する平面を有する平板状金属酸化物粒子とを、
    　ｐＨ５～７の水中において共存せしめることにより、前記平板状金属酸化物粒子の平面上に前記三角平板状銀ナノ粒子を吸着せしめて請求項１～６のうちのいずれか一項に記載の銀ナノ粒子複合体を得る、銀ナノ粒子複合体の製造方法。     A plurality of triangular tabular silver nanoparticles having a main plane shape of a triangle or a substantially triangular shape, an initial average longest diameter of the main plane of 20 to 120 nm, and an initial average thickness of 5 nm or more and less than 20 nm;
    A plate-like metal oxide comprising a metal oxide having a positive zeta potential at pH 5 to 7 and having a plane having an average diameter of 16.7 to 500 times the initial average longest diameter of the triangular tabular silver nanoparticles as a plane. With the particles
    The silver nanoparticle according to any one of claims 1 to 6, wherein the triangular tabular silver nanoparticles are adsorbed on a plane of the tabular metal oxide particles by coexisting in water having a pH of 5 to 7. A method for producing a silver nanoparticle composite, which obtains a particle composite.
  12. 　前記平板状金属酸化物粒子の平面上に前記三角平板状銀ナノ粒子を吸着せしめた後に、密封容器内において５０時間以上保存する安定化工程をさらに備える請求項１１に記載の銀ナノ粒子複合体の製造方法。 12. The silver nanoparticle composite according to claim 11, further comprising a stabilization step of storing the triangular tabular silver nanoparticles on the plane of the tabular metal oxide particles and then storing them in a sealed container for 50 hours or more. Manufacturing method.
  13. 　前記三角平板状銀ナノ粒子と前記平板状金属酸化物粒子との配合比（三角平板状銀ナノ粒子の質量：平板状金属酸化物粒子の質量）が１：１００～３０：１００である請求項１１又は１２に記載の銀ナノ粒子複合体の製造方法。 The blending ratio of the triangular tabular silver nanoparticles and the tabular metal oxide particles (mass of triangular tabular silver nanoparticles: mass of tabular metal oxide particles) is 1: 100 to 30: 100. A method for producing a silver nanoparticle composite according to 11 or 12.
PCT/JP2012/068677 2011-08-19 2012-07-24 SILVER NANOPARTICLE COMPOSITE, SILVER NANOPARTICLE COMPOSITE SUSPENSION USING THIS, COMPOSITION FOR γ-RAY-SENSITIVE SENSOR FORMATION AND γ-RAY SENSITIVE SENSOR, AND METHOD FOR MANUFACTURING SILVER NANOPARTICLE COMPOSITE WO2013027525A1 (en)

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JP7398164B1 (en) 2023-04-07 2023-12-14 プリマール株式会社 Cosmetics and cosmetic manufacturing methods

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