JP6083003B2 - COMPOSITE HOLLOW PARTICLE, PROCESS FOR PRODUCING THE SAME, AND FLUORESCENT MATERIAL - Google Patents

Description

  The present invention relates to a composite hollow particle in which hollow particles made of silica shells and phosphor particles are combined, a method for producing the composite hollow particle, and a fluorescent material using the composite hollow particle.

  Since hollow particles have various characteristics such as low density, high specific surface area, and ability to enclose substances, they are applied in a wide range of fields such as lightweight materials, heat insulating materials, optical materials, and medical fields. In recent years, research and development of hollow particles having a particle diameter of about 50 to 100 nm, especially silica hollow particles, has been actively conducted. Since the silica itself has transparency, the particle diameter is less than or equal to the visible light wavelength, and the inside is a cavity and has little light absorption, it has high light transmittance. In addition, since the inside of each particle is hollow, the area of the interface between the air and the silica shell increases, and because the particle interface is inside the aggregate of many particles, light scattering does not easily occur and excellent light transmission And light scattering properties. Such silica hollow particles and the production method thereof are disclosed in, for example, Patent Document 1.

  Zinc oxide (ZnO) fine particles are known as phosphor particles. Although there are various theories on the light emission mechanism of zinc oxide fine particles, it is often explained that it is caused by oxygen defects in the wurtzite crystal of zinc oxide. In particular, it is said that the fluorescence intensity or the fluorescence peak wavelength changes depending on the particle diameter.

  A method for producing zinc oxide fine particles is disclosed in Patent Document 2, in which a mixed solution of zinc carboxylate and alcohol is mixed with and / or brought into contact with a substance containing and / or generating ammonia, and the mixed solution is used. It is said that zinc oxide ultrafine particles containing substantially no alkali can be formed by hydrolyzing to produce zinc oxide ultrafine particles and then distilling off ammonia.

  On the other hand, in Patent Document 3, zinc ions or a zinc compound is introduced into pores of a silica-based inorganic porous material such as silica gel using a solution of a zinc compound such as ethanol or water, and heated and fired in an oxidizing atmosphere. Thus, a technique for enclosing zinc oxide fine particles in the pores of a porous body is disclosed.

Japanese Patent No. 4654428 JP-A-10-120419 JP 2003-201447 A

  Taking advantage of the characteristics of the silica hollow particles, it is expected that an optical material with high luminous efficiency that emits fluorescence and transmits and scatters fluorescence can be produced by supporting phosphor particles in the shell of the silica hollow particles.

  Further, when the phosphor particles are supported on the shell of the silica hollow particles, it is desirable that the phosphor particles can be supported on the surface of the silica shell of the silica hollow particles directly at a temperature near room temperature.

  Although Patent Document 2 discloses that zinc oxide fine particles can be produced at a low temperature of 200 ° C. or lower by hydrolysis using ammonia as a catalyst, a composite material of zinc oxide fine particles and silica fine particles is produced. Is not disclosed. Moreover, in patent document 3, in order to make the zinc compound in the pores of porous materials, such as a silica gel, into a zinc oxide, it is supposed that the heating of 400 degreeC or more is required.

  In view of the above points, the first object of the present invention is to provide composite hollow particles in which silica hollow particles and phosphor particles are combined. The second object of the present invention is to provide a method for producing a composite hollow particle capable of supporting phosphor particles on the surface of a silica shell of a silica hollow particle directly at a temperature around room temperature. To do. Another object of the present invention is to provide a fluorescent material using composite hollow particles and an applied product using the fluorescent material.

  The present inventors have found that the above problem can be solved by impregnating silica hollow particles with a solution in which a zinc source is dissolved and adding the particles after filtration to an alkali-containing solution. That is, according to the present invention, the following composite material and the manufacturing method thereof are provided.

  A first feature of the present invention is constituted by a composite material of silica and zinc-containing crystal, comprising silica hollow particles composed of silica shells, and zinc-containing crystal particles supported on at least one of an outer surface and an inner surface of the silica shell. Composite hollow particles. This zinc-containing crystal particle has a first angle group of 2θ = (32 °, 35 °, 36 °) and 2θ = (9 °, 18 °, 27 °, 36 °) in an X-ray diffraction pattern by CuKα rays. The second angle group, 2θ = (10 °, 15 °, 17 °, 20 °, 21 °, 25 °, 28 °, 32 °, 36 °) and the third angle group and 2θ = (32 °, 34 °, 38 °) has a diffraction peak in any one or more of the fourth angle group.

  The first object described above is achieved by the first feature of the present invention. The composite hollow particle of the first feature of the present invention is a fluorescent material having high light emission luminance because zinc-containing crystal particles, which are phosphors, are supported on silica hollow particles having high light transmission and light scattering properties. Can be used.

  The second feature of the present invention is a method for producing composite hollow particles that obtains composite hollow particles by sequentially performing a first step, a second step, and a third step. In the first step, prepared are silica hollow particles comprising silica shells having pores, a zinc source-containing solution in which a zinc source is dissolved in water or an organic solvent, and an alkali-containing mixed liquid in which an alkali source and a solvent are mixed. To do. In the second step, silica hollow particles are impregnated with one liquid of a zinc source-containing solution and an alkali-containing mixed solution, and particles in which one liquid enters the inside of the silica hollow particles through pores are obtained. In the third step, the other liquid of the zinc source-containing solution and the alkali-containing mixed solution and the particles obtained in the second step are mixed and stirred. Thereby, a zinc source and an alkali source are reacted to generate zinc-containing crystal particles on at least one of the outer surface and the inner surface of the silica shell.

  According to the second aspect of the present invention, the zinc-containing crystal particles can be generated by mixing and stirring in the third step at a temperature near room temperature, and the generated zinc-containing crystal particles are converted into silica shells of silica hollow particles. Can be directly supported on the surface of the substrate.

  The third feature of the present invention is a fluorescent material using the composite hollow particles of the first feature of the present invention.

  A fourth feature of the present invention is light guide plate type flat panel illumination using the fluorescent material of the third feature of the present invention.

  A fifth feature of the present invention is light-emitting diode illumination including a fluorescent material.

  A sixth feature of the present invention is an illumination that includes a light source that emits light and a phosphor that emits light by the light emitted from the light source, and that emits both the light from the light source and the light emitted from the phosphor. Device. In this illuminating device, the phosphor is made of the fluorescent material according to the third feature of the present invention.

It is a figure which shows t plot of pore presence (A, B) and absence (C) in the shell of a silica hollow particle. It is a figure which shows the SEM image (transmission electron mode) of the silica hollow particle which is a raw material. It is a schematic diagram of FIG. 2A. It is a SEM image (transmission electron mode) of the composite material hollow particle which carry | supported the zinc containing crystal | crystallization nanoparticle on the shell surface of the silica hollow particle of this invention. It is a schematic diagram of FIG. 3A. It is a figure which shows the X-ray-diffraction pattern (XRD) of each sample at the time of changing the synthetic | combination conditions of the composite material hollow particle which carry | supported the zinc containing crystal | crystallization nanoparticle on the shell surface of the silica hollow particle of this invention. It is a figure which shows the photoluminescence (PL) characteristic of each sample shown in FIG. It is a figure which shows the light emission state of the sample of NaOH * 1/2 and stirring time 30min. It is a figure which shows the fluorescence color of the zinc containing crystal carrying | support silica hollow particle and the zinc containing crystal carrying | support silica solid particle which irradiated the light of excitation wavelength 350nm. It is a figure which shows the wavelength dependence of the fluorescence intensity of the zinc containing crystal carrying | support silica hollow particle and zinc containing crystal carrying | support silica solid particle which irradiated the light of excitation wavelength 350nm. It is sectional drawing which shows the structure of the illuminating device in one Embodiment of this invention. It is sectional drawing of the composite material hollow particle in FIGS. 9-1A. It is a conceptual diagram which shows the permeation | transmission and scattering of the light in the composite material hollow particle in FIG. 9-1A. It is sectional drawing which shows the structure of the illuminating device in the comparative example 1. FIG. 9B is a conceptual diagram illustrating light transmission and scattering in the composite solid particles in FIG. 9-2A. It is sectional drawing of the illuminating device in other embodiment of this invention. It is an enlarged view of the holding | maintenance part in FIG. 10-1A. It is sectional drawing of the composite material hollow particle in FIG. 10-1B. It is sectional drawing of the composite material hollow particle which is a modification with respect to FIG. 10-1C. It is sectional drawing of the holding | maintenance part of the illuminating device in the comparative example 2. It is a flowchart which shows the manufacturing process of the composite material hollow particle of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments, and changes, modifications, and improvements can be added without departing from the scope of the invention.

  The composite hollow particles of the present invention are those in which zinc-containing crystalline nanoparticles are deposited on at least one of the outer surface or inner surface of the shell of silica hollow particles having a particle diameter of 30 to 2000 nm. The particle size of the zinc-containing crystal nanoparticles is particularly preferably 1 nm to 20 nm from the viewpoint of emitting fluorescence, and the zinc-containing crystal particles of the present invention emit fluorescence having a peak wavelength of 500 to 600 nm. Silica hollow particles are in the form of a sphere, a spheroid, or a cube. Here, “spherical” means not only a sphere but also a shape similar to a sphere surrounded by a surface, and “spheroid” means not only a spheroid but also a spheroid surrounded by a surface. It refers to a similar shape, and the “cubic shape” is not limited to a cube, but a shape similar to a cube surrounded by a face. The hollow particles made of silica shells having such a spherical shape, spheroid shape, or cubic shape are, for example, calcium carbonate particles, polystyrene, etc. in the form of a spherical shape, spheroid shape, or cubic shape in a dry powder state. The polymer material is used as a core material. That is, it is manufactured by forming a silica shell on the surface of the core material and then removing the core material. The removal of the core material after the formation of the silica shell is performed by acid treatment or heating (for example, see Patent Document 1). The average particle diameter of the hollow particles is the average of the major axis and the minor axis in the case of a spheroid, and the length of one side in the case of a cube.

The thickness t of the silica shell of the hollow particles made of the silica shell is preferably 2 to 25 nm from the viewpoint of maintaining the strength of the hollow structure. The hollow silica particle shell has pores, the pore diameter is 0.5 nm to 10 nm, the average pore diameter is 2 nm or less (hereinafter, the average pore diameter is 2 nm or less is referred to as micropore), and the shell. The density is preferably 1.5 g / cm ³ or more. The shell density ρ _S here is obtained from the following formulas (1) and (2). The shell thickness t is measured by a transmission electron microscope, and the specific surface area S is obtained by applying the BET equation by nitrogen gas adsorption. M is the weight of the hollow particles, and r is the radius of the hollow particle core. The presence or absence of pores can be examined using a t plot as shown in FIG. A plot that can be approximated by a single straight line is non-porous, and a plot can be approximated by two straight lines, and if the straight line is bent downward on the side close to the origin, it can be determined that the micropore is present.

In addition, an average pore diameter is calculated | required from the nitrogen gas adsorption isotherm using BJH method, for example. The average particle diameter of the silica hollow particles and the average particle diameter of the zinc-containing crystal particles are determined from, for example, a scanning electron microscope observation photograph (SEM image).

  The method for producing a composite hollow particle of the present invention comprises impregnating silica hollow particles with a solution obtained by dissolving a zinc source in water or an organic solvent, mixing the particles obtained by filtration into an alkali-containing mixture, and stirring. This is a method for producing composite hollow particles in which zinc-containing crystalline nanoparticles are supported on the surface of silica hollow particles obtained in this manner.

  That is, as shown in FIG. 11, the method for producing a composite hollow particle of the present invention obtains composite hollow particles by sequentially performing a first step, a second step, and a third step. In the first step, silica-containing hollow particles composed of silica shells having pores, a zinc source-containing solution in which a zinc source is dissolved in water or an organic solvent, and an alkali-containing mixed solution in which an alkali source and a solvent are mixed as raw materials. And prepare. In the second step, silica hollow particles are impregnated with a zinc source-containing solution and then filtered to obtain particles. In the third step, the particles obtained in the second step and the alkali-containing mixed solution are mixed and stirred.

Silica hollow particles are impregnated with a solution prepared by dissolving a zinc source in water or an organic solvent, and the particles obtained by filtration are mixed with an alkali-containing mixed solution to adhere the generated zinc-containing crystals to the silica hollow particles. However, when preparing the zinc source-organic solvent mixed liquid impregnated in the silica hollow particles, as the zinc source, zinc chloride (ZnCl ₂ ), zinc sulfate (ZnSO ₄ ), zinc nitrate (Zn (NO ₃ ) ₂ ), Zinc acetate (Zn (OAc) ₂ ), zinc sulfide (ZnS), zinc hydroxide (Zn (OH) ₂ ), and the like can be used. Among them, anhydrous zinc acetate is preferable from the viewpoint of versatility. On the other hand, as the organic solvent, it is necessary that the silica hollow particles and the generated zinc-containing crystal particles have good dispersibility in the solvent. For example, alcohols, glycols, glycol esters, ketones such as acetone, or These two or more kinds of mixed solvents can be mentioned, among which alcohols are preferable, and ethanol is particularly preferable.

When the particles obtained by filtration are mixed with an alkali-containing mixed solution, alkali serves to change zinc acetate into zinc-containing crystals. Sodium hydroxide (NaOH), potassium hydroxide (KOH), Ammonium hydroxide (NH ₄ OH) and lithium hydroxide (LiOH) are preferably used, and an alcohol is preferable as a solvent of a mixed solution with an alkali source, and ethanol is particularly preferable. In the case of a mixed solution of sodium hydroxide and ethanol, the amount of sodium hydroxide contained in ethanol is preferably 5 g / L to 50 g / L, and an alkali-containing mixed solution containing silica hollow particles and a zinc source is used at around room temperature (20 The time for mixing and stirring at ˜40 ° C. is preferably 1 minute to 120 minutes, and particularly preferably 5 minutes to 60 minutes. In addition, you may use water as a solvent of an alkali containing liquid mixture. Moreover, the alkali-containing liquid mixture is not limited to a state in which the alkali source is dissolved in the solvent, and may be in a state in which the alkali source is not dissolved in the solvent.

  Further, in the present invention, when the silica hollow particles are impregnated with a solution in which the zinc source is dissolved in water or an organic solvent, the shell of the silica hollow particles has micropores. Get into the cavity. When the solution of silica hollow particles and zinc source is mixed with the alkali-containing solution after filtration, the zinc source in the shell and the alkali source diffusing from outside the shell must chemically react near the shell of the silica hollow particle. By this, zinc-containing crystal particles are deposited on the inner surface or outer surface of the shell. This reaction occurs at temperatures near room temperature. In addition, this reaction can be reversed to the above procedure. Silica hollow particles are impregnated in an alkali-containing solution, alkali is introduced into the shell, and the filtered particles are mixed into the zinc source-containing solution. As a result, zinc-containing crystals are formed near the shell of the silica hollow particles. When the silica hollow particle shell is non-porous, the solution does not enter the hollow interior. On the other hand, when the pores become large, the zinc source or alkali-containing solution that has entered will ooze again. Therefore, it is preferable to use hollow particles having micropores in the shell in producing the composite hollow particles of the present invention.

  Thus, according to the method for producing composite hollow particles of the present invention, zinc-containing crystalline nanoparticles can be supported on the surface of silica hollow particles directly at a temperature near room temperature.

  In the above description, in the second step, the silica source particles are impregnated with the zinc source-containing solution, and the zinc source-containing solution enters the inside of the silica hollow particles through the pores. After obtaining the particles contained in the inside, the third step was performed by filtering the particles. However, the third step may be performed without filtering the particles. However, if the third step is performed without filtering, the above-described chemical reaction occurs not only near the shell of the silica hollow particles but also outside the silica hollow particles. For this reason, it is preferable to filter in a 2nd process.

  In addition, after the stirring in the third step, the suspension after stirring is filtered, and the composite hollow particles obtained by filtering can be used without being dried or can be used after being dried. Further, the suspension after stirring may be used as it is.

  In the composite hollow particle of the present invention, nanometer-sized (1 nm to 20 nm) zinc-containing crystal particles are supported on the outer surface and / or inner surface of the silica hollow particle, and incident light on the silica hollow particle is incident on the hollow particle. In addition to light scattering on the outer surface of the shell, light scattering from the inner surface of the shell is superimposed, increasing the fluorescence intensity. As a result, it emits fluorescence having a high light transmittance and light scattering and a peak wavelength of 500 nm to 600 nm. For example, when used in combination with a blue light emitting diode (LED), white light or light with a wavelength close to this can be obtained. Can be released. Thus, the composite hollow particle of the present invention can be used as a highly light-scattering fluorescent material.

  Therefore, it can apply to the light-guide plate type flat panel illumination shown to FIGS. 9-1A using the highly light-scattering fluorescent material of this invention. Due to the above effect, a luminance of 20% to 40% higher than the fluorescence intensity of the solid particles of Comparative Example 1 shown in FIG. 9-2A can be obtained. On the other hand, as shown in FIG. 10-1A, the present invention can be applied to high-intensity or energy-saving LED lighting including the high-light-scattering fluorescent material of the present invention instead of the solid yellow fluorescent material. In this case as well, the silica hollow particles carrying the fluorescent particles of the present invention have a brightness of 20% to 40% higher than the solid silica particles carrying the fluorescent particles.

  The lighting apparatus 10 according to the embodiment of the present invention illustrated in FIG. 9-1A includes a blue LED 11, a light guide plate 12, and a light scattering plate 13. The blue LED 11 is a light source that emits blue light. The light guide plate 12 has a front surface 12a and a back surface 12b, and is a plate that uniformly emits light from the light source incident inside from the planar end portion 12c from the front surface 12a. A reflector 14 is provided on the back surface 12 b of the light guide plate 12. The light source 11 is disposed at the planar end 12 c of the light guide plate 12. The light scattering plate 13 is disposed on the surface 12 a of the light guide plate 12. The light scattering plate 13 is obtained by applying a fluorescent material 16 using the composite hollow particles 15 of the present invention as a phosphor on the surface of a transparent plate 17.

  As shown in FIG. 9-1B, the composite hollow particle 15 has a zinc-containing crystal 15b supported on the outer surface of the silica hollow particle 15a. The zinc-containing crystal 15b may be supported on both the outer surface and the inner surface of the silica hollow particle 15a, or may be supported only on the inner surface of the silica hollow particle 15a.

  In this illuminating device 10, the light of the light source 11 incident from the planar end portion 12 c of the light guide plate 12 travels inside the light guide plate 12 and is reflected by the reflection plate 14, whereby the light from the surface 12 a of the light guide plate 12. It is released uniformly. The light emitted from the surface 12 a of the light guide plate 12 passes through the light scattering plate 13. At this time, the composite hollow particles 15 are excited by the light emitted from the blue LED 11 to emit fluorescence. For this reason, the illuminating device 10 irradiates both the light emitted from the blue LED 11 and the light emitted from the composite hollow particles 15. As a result, the illumination device 10 irradiates white light or light having a wavelength close thereto.

  The illumination device 100 of Comparative Example 1 shown in FIG. 9-2A is a silica solid particle as shown in FIG. 9-2B as the fluorescent material 16 of the light scattering plate 13 in the illumination device 10 shown in FIG. 9-1A. The composite material solid particles 18 carrying the zinc-containing crystals are used.

  When comparing the illumination device 100 of the comparative example 1 with the illumination device 10 of FIG. 9-1A, in the illumination device 100 of the comparative example 1, as shown in FIG. It will attenuate. On the other hand, as shown in FIG. 9-1C, the composite material hollow particles 15 have higher light transmission and light scattering properties than the composite material solid particles 18, so that the fluorescence intensity of the composite material solid particles 18 is increased. In comparison, 20% to 40% higher luminance is obtained. For this reason, according to the illuminating device 10 of FIG. 9-1A, the brightness | luminance of white light improves rather than the illuminating device 100 of the comparative example 1. FIG.

Lighting apparatus 20 according to another implementation of the invention shown in FIG. 10-1A is a bullet-shaped LED lighting. The lighting device 20 includes a blue LED 21, a lead frame 22, and a cover 23. The lead frame 22 has a holding portion 22 a that holds the blue LED 21, and serves as a holding member that holds the blue LED 21 and an electric wiring member that is electrically connected to the blue LED 21. The cover 23 is made of a transparent material and covers the blue LED 21 and the holding portion 22 a of the lead frame 22.

  As shown to FIG. 10-1B, the holding | maintenance part 22a is concave shape, and blue LED21 is arrange | positioned at the concave bottom part. Further, a fluorescent material using the composite hollow particle 15 of the present invention as a phosphor is disposed around the blue LED 21. As shown in FIG. 10-1C, the composite hollow particle 15 has a zinc-containing crystal 15b supported on the inner surface of the silica hollow particle 15a. In this case, the composite material hollow particles 15 emit yellow light. As shown in FIG. 10-1D, the zinc-containing crystal 15b may be supported only on the outer surface of the silica hollow particle 15a, or may be supported on both the outer surface and the inner surface of the silica hollow particle 15a. Also good. When the zinc-containing crystal 15b is supported on the outer surface of the silica hollow particle 15a, the composite hollow particle 15 emits yellowish green light.

  Also in this illuminating device 20, it irradiates both the light which blue LED21 irradiated, and the light which the composite material hollow particle 15 light-emitted. As a result, the illumination device 10 irradiates white light or light having a wavelength close thereto.

  The illuminating device 200 of the comparative example 2 shown to FIGS. 10-2 uses the composite material solid particle 18 like the illuminating device 100 of the comparative example 1 as a fluorescent material inside the holding | maintenance part 22a.

  Since the composite hollow particles 15 have higher light transmission and light scattering properties than the composite solid particles 18, a brightness 20% to 40% higher than the fluorescence intensity of the composite solid particles 18 can be obtained. For this reason, according to the illuminating device 20 of FIG. 10-1A, the brightness | luminance of white light improves rather than the illuminating device 200 of the comparative example 2. FIG.

  EXAMPLES Hereinafter, although this invention is further demonstrated based on an Example, this invention is not limited to these Examples.

  Table 1 shows the parameters of the hollow silica particles used in the synthesis in Examples and Comparative Examples.

(Examples 1-14, Comparative Examples 1-2)
In this experiment, as shown in Table 1, hollow silica particles having a particle diameter of about 100 nm, a cubic shape, and a specific surface area of 180 m ² / g were used. First, 200 mg of the hollow particles were placed in a separable flask connected to a separatory funnel and a vacuum pump, heated to 200 ° C. with a mantle heater, and dried under reduced pressure for 2 hours. Thereafter, 2.29 g (0.0125 mol) of anhydrous zinc acetate (manufactured by Wako Pure Chemical Industries) was dissolved in 150 mL of ethanol (99.5%, manufactured by Wako Pure Chemical Industries) in the hollow particles cooled to room temperature. A zinc-ethanol solution was added and stirred with a magnetic stirrer for 15 minutes.

  The stirred suspension was subjected to suction filtration with an aspirator using an omnipore membrane (manufactured by Millipore) having a pore diameter of 0.1 μm. The obtained particles were transferred to a beaker, and 0.25 g (0.00625 mol), 0.5 g (0.0125 mol), 1.0 g (0.025 mol), 2.0 g (0.05 mol), 4.0 g (0 0.1 mol) of sodium hydroxide (manufactured by Wako Pure Chemical Industries, Ltd.) in 50 mL of ethanol was added, and the mixture was stirred for 5 minutes, 30 minutes, and 60 minutes with a magnetic stirrer. There are 16 types of samples, 5 types of sodium hydroxide, 3 types of stirring time (4 types including 120 minutes only in the case of 0.25 g of sodium hydroxide). The suspension after stirring was filtered again under reduced pressure, and the resulting particles were vacuum-dried at room temperature for 24 hours to obtain silica / zinc-containing crystal composite hollow particles.

  As a shape evaluation of the composite composite hollow particles, observation by a scanning electron microscope (SEM) (manufactured by JSM-7600F / JEOL), and as a qualitative evaluation, powder X-ray diffraction (XRD) measurement by CuKα rays (manufactured by Ultimate IV / Rigaku) In addition, the fluorescence characteristics were evaluated by a spectrofluorometer (FP6500 / manufactured by JASCO).

  2A and 2B show a silica hollow particle as a raw material, and FIGS. 3A and 3B show a SEM image (transmission electron mode image) and a schematic diagram of the synthesized silica / zinc-containing crystal composite hollow particle, respectively. 2A and 2B, it can be seen that the hollow silica particles used as a raw material have a cubic shape, a particle diameter of about 100 nm, and a shell thickness of about 10 nm. On the other hand, it can be seen from FIGS. 3A and 3B that fine particles having a size of several nanometers are attached to the shell surface of the hollow silica particles. In this example, after impregnating the silica hollow particles of the raw material into the zinc acetate-ethanol solution, it was filtered once, and then reacted by adding the sodium hydroxide-ethanol solution, so that the zinc ion distribution was outside the silica shell. It is considered that the fine particles are concentrated on the surface and inner surface and are selectively deposited on the shell surface.

FIG. 4 shows an XRD pattern of the synthesized silica / zinc-containing crystal composite hollow particles. Here, NaOH x1, NaOH x0.5, NaOH x0.25, NaOH x2, and NaOH x4 are used in amounts of sodium hydroxide of 1.0 g, 0.5 g, 0.25 g, and 2. The time of 0 g and 4.0 g represents the stirring time of adding the sodium hydroxide-ethanol solution. In addition, “ZnO (Wako)” and “Zn (OAc) ₂ ” are obtained by measuring zinc oxide and anhydrous zinc acetate, which are Wako Pure Chemicals reagents, under the same conditions as the synthesized product, respectively.

  In all the synthesized samples, the peak of anhydrous zinc acetate as a raw material disappears and the peak of zinc oxide is observed. The peaks at 2θ = 32, 35, 36 (first angle group) are the zinc oxide peaks. However, the peaks of these zinc oxides are broadened, which is considered to be due to the fine particles of zinc-containing crystals. In addition, (NaOH × 1, 60 min) and (NaOH × 0.5, 60 min) have sharp peaks at 9 °, 18 °, 27 °, and 36 ° (second angle group), and the angle is a multiple. Therefore, the possibility that a layered zinc-containing crystal is formed is suggested. Also, among the samples, for example, (NaOH × 1/4, 5 min), 10 °, 15 °, 17 °, 20 °, 21 °, 25 °, 28 °, 32 °, 36 ° (third angle) Group) has a peak. In (NaOH × 1/2, 5 min), there are peaks at 2θ = 32 °, 34 °, and 38 ° (fourth angle group).

  The photoluminescence (PL) characteristics of the synthesized sample are shown in FIG. The wavelength of the excitation light is 350 nm. It was found that any sample showed a fluorescence peak wavelength of 550 to 560 nm and showed no significant difference, and emitted yellowish green to yellow light. In addition, it is considered that the fluorescence intensity increases as the peak near 34 ° in the XRD measurement spreads. With respect to the sample of NaOH × 1/4, the fluorescence intensity was large, but the confirmation by the SEM image showed that the loading of the zinc-containing crystal on the shell was very small. This is probably because the low concentration of sodium hydroxide took time to produce zinc-containing crystals, and zinc ions diffused out of the shell during synthesis. Further, regarding the NaOH × 2 and NaOH × 4 samples, although the support of zinc-containing crystals on the silica shell was confirmed by SEM, it was found that the crystallinity was very low by XRD measurement. Moreover, it was found that the fluorescence intensity was low in each PL measurement result. Furthermore, it was found that the NaOH x 2 and NaOH x 4 samples were not excellent in operability as a powder because of the effects of residual sodium hydroxide or phenomena such as deliquescence when stored in the atmosphere. .

The photograph which shows the light emission state of the sample of NaOH * 1/2 and stirring time 30min is shown in FIG. The wavelength of the excitation light is 365 nm, and the container is made of quartz. As shown in the photograph, it was found that yellow-yellow to yellow light was emitted.
Table 2 summarizes the amount of anhydrous zinc acetate and sodium hydroxide used in the synthesis and the molar ratio thereof, the amount ratio of sodium hydroxide and the alcohol in which it is dissolved, the combination of stirring time, and the sample evaluation results. In the physical property column, the confirmation result of the composite of the silica hollow particle and the zinc-containing crystal nanoparticle by SEM observation (○ is good, △ indicates that it is composited even a little, and × indicates that it is not composited at all), XRD Peaks of zinc-containing crystals as measured (2θ = (9 °, 18 °, 27 °, 36 °) and 2θ = (10 °, 15 °, 17 °, 20 °, 21 °, 25 °, 28 °, 32 (°, 36 °) and 2θ = (32 °, 34 °, 38 °) and any of the peaks of zinc oxide) (existence is indicated by ○, absence is indicated by ×), fluorescence intensity by PL measurement (especially The strong ones are categorized as ◎, the strong ones are 弱 い, the weak ones are Δ, and the ones that do not show fluorescence at all are X). In addition, about the sample synthesize | combined on the conditions of NaOH * 2, 60min (comparative example 1) and NaOH * 4, 60min (comparative example 2), the deliquescence considered to be derived from NaOH is strong, and it is easy to operate as a powder. It turns out that it is not excellent. Due to this deliquescence, PL measurement of NaOH × 2, 60 min and XRD measurement and PL measurement of NaOH × 4, 60 min could not be performed.

(Examples 15-18, Comparative Examples 3-6)
Silica hollow particles having a smaller density and larger pore diameter than the silica hollow particles used in Examples 1 to 14 (density about 1.5 g / cm³Average pore diameter of about 1.5 nm), and density of about 2.2 g / cm ³Table 3 shows Comparative Examples 3 to 6 using silica hollow particles having no pores. It can be seen that when the silica hollow particle shell has no pores, no zinc-containing crystals are formed on the shell surface.

(Examples 19 to 34)
Table 19 shows Examples 19 to 34 in which zinc nitrate, zinc chloride, zinc sulfide, and zinc sulfate were used as the zinc source (the solvent was water only when zinc sulfide and zinc sulfate were used as the zinc source). Silica / zinc-containing crystal composites were formed even with zinc sulfide and zinc sulfate in which the solvent was water instead of alcohol.

(Examples 35 to 46)
Table 5 shows Examples 35 to 46 using potassium hydroxide, lithium hydroxide, and aqueous ammonia as the alkali. It was found that a silica / zinc-containing crystal composite material was formed with lithium hydroxide or the like in addition to sodium hydroxide.

(Examples 47 to 62)
Examples 47 to 62 using 2-propanol, acetone, ethylene glycol, and diglyme instead of ethanol as the solvent are shown in Table 6. It was found that a silica / zinc-containing crystal composite material can be formed even with a versatile solvent other than ethanol.

(Examples 63 to 66)
Table 7 shows Examples 63 to 66 using a method of adding a zinc source solution after impregnating the hollow particles with alkali and filtering after conversely to Examples 1 to 62 above. It can be seen that even when the hollow particles are impregnated with alkali first, zinc-containing crystals can be formed in the vicinity of the shell of the silica hollow particles.

The fluorescence color and fluorescence intensity of the silica hollow particles (Hollow-ZnO) carrying the zinc-containing crystals of the present invention and the silica solid particles (Dense-ZnO) carrying the zinc-containing crystals were compared. As shown in FIG. 7, when each particle is dispersed in acetone and irradiated with light having an excitation wavelength of 350 nm, the zinc-containing crystal-supported silica hollow particles emit yellow-green fluorescence, and the zinc-containing crystal-supported silica solid particles are yellow. Fluorescence was emitted. Next, FIG. 8 shows the results of measurement of fluorescence characteristics when irradiated with light having an excitation wavelength of 350 nm. The wavelength dependence of the fluorescence intensity of zinc-containing crystal-supported silica hollow particles (Hollow-ZnO) and zinc-containing crystal-supported silica solid particles (Dense-ZnO) is almost the same. It can be assumed that the solid particles carrying zinc-containing crystals are about twice as large in the entire wavelength region, and that the light transmittance and light scattering properties of the hollow particles are high.

  The silica / zinc-containing crystal composite hollow particles of the present invention can be used as a fluorescent material.

Claims (15)

Silica hollow particles made of silica shell,
Comprising zinc-containing crystal particles supported on at least one of an outer surface and an inner surface of the silica shell,
The silica hollow particles have an average particle size of 30 to 2000 nm,
The zinc-containing crystal particles have an average particle size of 1 to 20 nm,
Said zinc-containing crystal grains, in X-ray diffraction pattern by CuKα line, 2 θ = (9 °, 18 °, 27 °, 36 °) angles group, 2θ = (10 °, 15 °, 17 °, 20 °, 21 °, 25 °, 28 °, 32 °, angles groups 36 °) and 2θ = (32 °, 34 ° , diffraction peaks at any one or more angles groups aNGLE groups 38 °) Composite hollow particles composed of a composite of silica and zinc-containing crystals.   The composite hollow particle according to claim 1, wherein a peak wavelength of fluorescence emitted from the composite material is 500 to 600 nm.   The composite hollow particle according to claim 1, wherein the silica shell has pores, and an average pore diameter of the pores is 2 nm or less. The composite hollow particle according to any one of claims 1 to 3 , wherein the zinc-containing crystal particles are supported on at least an inner surface of an outer surface and an inner surface of the silica shell. Silica hollow particles made of silica shell,
Comprising zinc-containing crystal particles supported on at least one of an outer surface and an inner surface of the silica shell,
The silica hollow particles have an average particle size of 30 to 2000 nm,
The zinc-containing crystal particles have an average particle size of 1 to 20 nm,
The zinc-containing crystal particles have a first angle group of 2θ = (32 °, 35 °, 36 °) and 2θ = (9 °, 18 °, 27 °, 36 °) in an X-ray diffraction pattern by CuKα rays. The second angle group, 2θ = (10 °, 15 °, 17 °, 20 °, 21 °, 25 °, 28 °, 32 °, 36 °) and the third angle group and 2θ = (32 °, 34 °, 38 °) is a method for producing a composite hollow particle composed of a composite material of silica and zinc-containing crystal having a diffraction peak in any one or more of the fourth angle group,
Ri Do silica shell having pores having an average particle diameter were mixed with 30~2000nm der Ru silica hollow particles, and zinc source containing solution a source of zinc dissolved in water or an organic solvent, an alkali source and a solvent A first step of preparing an alkali-containing liquid mixture;
A second step of impregnating the silica hollow particles with one of the zinc source-containing solution and the alkali-containing mixed liquid to obtain particles in which the one liquid has entered the silica hollow particles from the pores; ,
The zinc source-containing solution, the other liquid of the alkali-containing mixed solution, and the particles obtained in the second step are mixed and stirred to react the zinc source and the alkali source so that the outside of the silica shell. The manufacturing method of the composite hollow particle which obtains the said composite hollow particle by performing the 3rd process which produces | generates a zinc containing crystal particle in at least one of the surface and an inner surface. The method for producing composite hollow particles according to claim 5 , wherein the mixing and stirring in the third step are performed at a temperature of 20 to 40 ° C. The method for producing composite hollow particles according to claim 5 or 6 , wherein the hollow silica particles are made of the silica shell having pores having an average pore diameter of 2 nm or less. The composite material according to any one of claims 5 to 7 , wherein any one or more of anhydrous zinc acetate, zinc nitrate, zinc chloride, zinc sulfide, and zinc sulfate is used as a zinc source of the zinc source-containing solution. A method for producing hollow particles. One or more of sodium hydroxide, potassium hydroxide, lithium hydroxide and ammonia is used as an alkali source of the alkali-containing mixed solution, and ethanol, 2-propanol, acetone is used as a solvent of the alkali-containing mixed solution. The method for producing composite hollow particles according to any one of claims 5 to 8 , wherein at least one of ethylene glycol, diglyme and water is used. While using sodium hydroxide and ethanol as the alkali source and solvent of the alkali-containing mixture, the amount of sodium hydroxide contained in the ethanol is 5 g / L to 50 g / L,
The method for producing composite hollow particles according to any one of claims 5 to 8 , wherein the mixing and stirring time in the third step is 1 minute to 120 minutes. A fluorescent material using the composite hollow particles made of a composite of silica and zinc-containing crystals,
The composite hollow particles are
Silica hollow particles made of silica shell,
Comprising zinc-containing crystal particles supported on at least one of an outer surface and an inner surface of the silica shell,
The silica hollow particles have an average particle size of 30 to 2000 nm,
The zinc-containing crystal particles have an average particle size of 1 to 20 nm,
The zinc-containing crystal particles have a first angle group of 2θ = (32 °, 35 °, 36 °) and 2θ = (9 °, 18 °, 27 °, 36 °) in an X-ray diffraction pattern by CuKα rays. The second angle group, 2θ = (10 °, 15 °, 17 °, 20 °, 21 °, 25 °, 28 °, 32 °, 36 °) and the third angle group and 2θ = (32 °, 34 °, 38 °) a fluorescent material having a diffraction peak in one or more angle groups of the fourth angle group. Light guide plate type flat panel illumination using the fluorescent material according to claim 11 . Light emitting diode illumination including the fluorescent material according to claim 11 . A light source that emits light;
A phosphor that emits light by light emitted from the light source,
An illumination device that irradiates both light from the light source and light emitted from the phosphor,
The said fluorescent substance is comprised with the fluorescent material of Claim 11 , The illuminating device characterized by the above-mentioned. The lighting device according to claim 14 , wherein the light source is a blue light emitting diode.