JP5120112B2 - Method for producing zinc oxide fine particles and method for producing dispersion using zinc oxide fine particles obtained by the method - Google Patents

Description

The present invention relates to a method for producing zinc oxide fine particles having high productivity, high crystallinity, and excellent dispersibility, a method for producing a dispersion using the zinc oxide fine particles obtained by the method, and the like .

  Usually, zinc oxide fine particles obtained by a wet method have been used as a green light emitting material because of low crystallinity and many defects.

  On the other hand, it can be applied to ultraviolet light sources and ultraviolet lasers that have lost the green light emission, and has a dominant emission wavelength in the ultraviolet region, and is a dispersion of highly crystalline zinc oxide particles and highly crystalline zinc oxide particles dispersed The body is sought. Currently, the following techniques are known as methods for producing fine zinc oxide particles having excellent dispersibility.

  A step of reacting an alkali carbonate with an aqueous zinc oxide slurry to obtain basic zinc carbonate, a step of heating and aging the basic zinc carbonate, and a group of IIIB element, IVB group element and Fe in the resulting aging solution A step of mixing and re-ripening an aqueous salt of at least one element selected from the following: a step of dehydrating and drying the aged product, a step of firing the resulting dried product, and a step of crushing the fired product A method for producing a conductive zinc oxide powder, which is characterized in that it is carried out, is disclosed (for example, see Patent Document 1). This Patent Document 1 describes that firing is performed at a temperature of 300 ° C. or more and 600 ° C. or less. In a specific example, firing is performed at 400 ° C. By the said manufacturing method, the electroconductive zinc oxide powder provided with the outstanding dispersibility and electroconductivity provision characteristic can be provided.

A method for producing a zinc oxide gel by basic hydrolysis in at least one alcohol or alcohol / water mixture, wherein the zinc oxide is a completely flocculent mass that precipitates initially formed during hydrolysis. A method is disclosed in which the mixture is aged until the mixture is concentrated, and then the precipitate is concentrated to a gel and separated from the supernatant phase (see, for example, Patent Document 2). In this patent document 2, sodium hydroxide and potassium hydroxide are mentioned as a base used for basic hydrolysis. By the above method, it is possible to provide nano-sized zinc oxide that exhibits strong UV absorption even in the UV-A region and also has excellent dispersion characteristics that minimize scattering.
International Publication No. 2004/058645 (Claim 2, page 3, lines 24-25, page 16, lines 11-14, page 23, lines 14-26, line 3) Japanese translation of PCT publication No. 2002-537219 (Claim 3, [0015], [0025])

  However, in the method disclosed in Patent Document 1, it is necessary to go through a multi-step process, and it is necessary to fire at a high temperature such as 400 ° C. Furthermore, in order to improve the dispersibility of the powder sintered by high-temperature firing, a step of crushing the fired product is required, which has a problem of low productivity.

  Moreover, in the method shown in the above-mentioned Patent Document 2, since the zinc oxide fine particles are obtained by hydrolysis with a base in alcohol, the baking step can be omitted when obtaining the zinc oxide fine particles. At this stage, the alkali metal is mixed in, so that more cleaning steps are required, and the alkali metal is mixed as an impurity in the finally obtained zinc oxide fine particles. Moreover, the crystallinity of the zinc oxide nanoparticles obtained by this method was relatively low.

  A first object of the present invention is to provide a method for producing zinc oxide fine particles, which can obtain alkali-free zinc oxide fine particles with high productivity without going through a multi-step process.

  A second object of the present invention is to provide a method for producing zinc oxide fine particles, which can obtain zinc oxide fine particles having high crystallinity, having a light emission wavelength dominant in the ultraviolet region, and having excellent dispersibility. is there.

  A third object of the present invention is to provide a method for producing zinc oxide fine particles capable of controlling the shape of the fine particles to a desired shape.

A fourth object of the present invention is to provide a method for producing zinc oxide fine particles, a dispersion, an ultraviolet light source, and an ultraviolet laser having high crystallinity, a dominant emission wavelength in the ultraviolet region, and excellent dispersibility. .

The invention according to claim 1 prepares a mixed solution by mixing a zinc compound, acetic acid and glycol, and irradiates the prepared mixed solution with microwaves and holds it at a temperature of 50 to 200 ° C. Zinc oxide fine particles characterized in that, when measured by X-ray diffraction, zinc oxide fine particles having a maximum peak half-value width of 0.5 degrees or less are measured when measured by X-ray diffraction It is a manufacturing method.

In the invention according to claim 1, by using glycol as a manufacturing raw material, the prepared mixture can be irradiated with microwaves in one pot, and the zinc oxide fine particles can be produced with very high productivity without passing through a multi-step process. Can be generated. In addition, since the microwaves are irradiated and held by heating, the reaction can proceed efficiently in a short time compared to an external heating method using heat conduction such as an oil bath. Since no alkali metal is used as the production raw material, alkali-free zinc oxide fine particles can be obtained. In addition, if the half width of the maximum peak in the X-ray diffraction pattern is 0.5 degrees or less, fine particles having high crystallinity, a dominant emission wavelength in the ultraviolet region, and excellent dispersibility are obtained. Can be confirmed.

  The invention according to claim 2 is the invention according to claim 1, wherein the zinc compound used as a raw material is a method for producing zinc oxide fine particles which are coarse particles of zinc oxide having a particle size of submicron or more and 50 μm or less. .

  In the invention according to claim 2, coarse particles of zinc oxide having a particle size of submicron or more and 50 μm or less are suitable for a zinc compound used as a raw material because they can be obtained at low cost.

  The invention according to claim 3 is the invention according to claim 1, wherein the zinc compound used as a raw material is zinc acetate fine particles.

  In the invention which concerns on Claim 3, zinc acetate is suitable as a zinc compound used as a raw material at the point which can be obtained cheaply and is easy to handle.

  The invention according to claim 4 is the invention according to claim 1, wherein the glycol used as a raw material is ethylene glycol, propylene glycol, 1,3-propanediol, diethylene glycol, 1,3-butanediol, or triethylene glycol. This is a method for producing zinc oxide fine particles.

  In the invention according to claim 4, the glycol compound of the above type is suitable as a glycol used as a raw material because the shape of the obtained zinc oxide fine particles can be controlled to various shapes such as granular, scale-like, rod-like, and polygonal. .

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the microwave frequency is a frequency within a range of 890 to 940 MHz, 2400 to 2500 MHz, or 5725 to 5875 MHz. This is a method for producing fine particles.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the zinc oxide fine particles are heated for 0.5 to 20 minutes up to the holding temperature of heating by microwave irradiation. It is a manufacturing method.

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the heating and holding time by microwave irradiation is 1 to 60 minutes.

The invention according to claim 8 is the invention according to any one of claims 1 to 7 , wherein the generated zinc oxide fine particles are spherical, needle-like, plate-like, polygonal, polygonal pyramidal, polygonal and This is a method for producing zinc oxide fine particles which are particles having at least one shape selected from the group consisting of rods.

The invention according to claim 9 is the invention according to any one of claims 1 to 7 , wherein the generated zinc oxide fine particles are in the form of needles, plates, polygons, polygonal pyramids, in addition to spherical particles. It is a method for producing zinc oxide fine particles composed of two or more types of particle shapes including particles having at least one shape selected from the group consisting of a polygonal shape and a rod shape.
The invention according to claim 10 is the invention according to any one of claims 1 to 9, wherein after the mixture solution is irradiated with microwaves, the reaction solution obtained is centrifuged to obtain a white color from the reaction solution. A step of separating the precipitate, a step of redispersing the separated white precipitate in a solvent, and centrifuging the dispersion, repeating the washing of the white precipitate a plurality of times, and the washed white precipitate And a step of vacuum drying the product at 25 to 60 ° C. to produce zinc oxide fine particles.

The invention according to an eleventh aspect is the production of a dispersion comprising a step of producing zinc oxide fine particles by the production method according to any one of claims 1 to 10 and a step of dispersing the zinc oxide fine particles in a dispersion medium. Is the method .

In the invention which concerns on Claim 11 , the dispersion which has the outstanding dispersibility can be obtained by using the zinc oxide microparticles | fine-particles obtained by the said manufacturing method .

The invention according to claim 12 is the invention according to claim 11 , wherein the zinc oxide fine particles include at least both a triangular pyramid shape and a spherical shape, and when all the shapes constituting the fine particles are 100%, a triangular shape is obtained. This is a method for producing a dispersion in which the ratio of the conical shape is in the range of 10 to 40%.

The invention according to claim 13 is the invention according to claim 11 , wherein the zinc oxide fine particles include at least a rod-like shape having an aspect ratio of 3 to 10, and when all the shapes constituting the fine particles are 100%, This is a method for producing a dispersion in which the proportion of the rod-like shape is in the range of 80 to 99%.

The invention according to claim 14 is a method for producing a zinc oxide film , comprising a step of obtaining a dispersion by the production method according to any one of claims 11 to 13 and a step of forming a film using the dispersion. is there.

A fifteenth aspect of the present invention is a phosphor manufacturing method including a step of obtaining a zinc oxide film by the manufacturing method according to the fourteenth aspect .

The invention according to claim 16 includes the steps of obtaining a zinc oxide fine particle dispersion by the production method according to any one of claims 11 to 13, the ultraviolet light source using this zinc oxide nanoparticle dispersion as an ultraviolet light-emitting material A step of obtaining the ultraviolet light source .

The invention according to claim 17, obtaining a zinc oxide fine particle dispersion by the production method according to any one of claims 11 to 13, an ultraviolet laser using this zinc oxide nanoparticle dispersion as an ultraviolet light-emitting material A process for obtaining an ultraviolet laser .

  The method for producing fine zinc oxide particles according to the present invention uses glycol as a production raw material, and only irradiates the prepared mixture with microwaves in one pot. Thus, zinc oxide fine particles can be obtained. In addition, since it is heated and held by irradiation with microwaves, the reaction can proceed efficiently in a short time compared to external heating methods using heat conduction such as oil baths, etc., so it is very productive and has a small particle size Zinc oxide fine particles having high dispersibility, high crystallinity, a dominant emission wavelength in the ultraviolet region, and excellent dispersibility can be obtained. In addition, since alkali metal is not used as a production raw material, alkali-free zinc oxide fine particles can be obtained.

  Next, the best mode for carrying out the present invention will be described.

In the method for producing zinc oxide fine particles of the present invention, a zinc compound, acetic acid and glycol are mixed to prepare a mixed solution, and the prepared mixed solution is irradiated with microwaves and held at a temperature of 50 to 200 ° C. The average particle size is 200 nm or less , and when measured by X-ray diffraction, zinc oxide fine particles having a maximum peak half-value width of 0.5 degrees or less in the X-ray diffraction pattern obtained by the measurement are generated. To do.

  By using glycol as a production raw material, zinc oxide fine particles can be obtained with very high productivity without passing through a multi-step process only by irradiating the prepared mixture with microwaves in one pot. In the external heating method using heat conduction such as an oil bath, since it takes 30 to 60 minutes to raise the temperature to the holding temperature, the present invention heats by applying microwaves. It is possible to efficiently raise the temperature to the holding temperature in a very short time of 5 to 20 minutes. For this reason, particles having a small particle size can be obtained as compared with fine particles obtained from an external heating method. Further, the time required for cooling is significantly shorter than that of the external heating method, which is suitable for suppressing the production of by-products and controlling the reaction, that is, controlling the particle size. Furthermore, since it is heated and held by irradiating microwaves, the reaction can be carried out efficiently in a short time compared to an external heating method using heat conduction such as an oil bath, so that the productivity is very high and the crystallinity is high. Zinc oxide microparticles having a high emission wavelength dominant in the ultraviolet region and excellent dispersibility can be obtained. In addition, since alkali metal is not used as a production raw material, alkali-free zinc oxide fine particles can be obtained.

  As a production raw material, water may be further added, and the particle size can be controlled by the amount of water added, such as the particle size of the zinc oxide fine particles produced can be increased by increasing the amount added. .

  When a mixture obtained by mixing a zinc compound, acetic acid and glycol is heated to produce zinc oxide fine particles, acetic acid or glycol is adsorbed on the surface of the zinc oxide fine particles in the reaction solution, and the zinc oxide fine particles It is considered that the state in which they do not aggregate is maintained. In that case, since a compound having two hydroxyl groups in one molecule, such as glycol, is adsorbed on the surface of the zinc oxide fine particles at two locations, the adsorption state is expected to be very stable. Therefore, the crystal growth of zinc oxide fine particles is inhibited by acetic acid and glycol stably adsorbed on the surface of the fine particles, and the crystal growth proceeds at a very slow rate. It is thought that fine particles will be generated.

  In addition, since acetic acid and glycol are stably adsorbed on the surface of the generated zinc oxide fine particles having an average particle diameter of 200 nm or less, it is very difficult to disperse the zinc oxide fine particles in the solvent. It can be a stable dispersion.

  Further, when an additive for modifying the surface of the generated zinc oxide fine particles is added, a more stable dispersion can be obtained. The additive is not particularly limited as long as it modifies the surface of zinc oxide, but a polymer dispersant, Si, Ti, Al-based coupling agent and the like are particularly preferable.

  As a zinc compound used as a raw material, zinc oxide coarse particles having a particle size of submicron or more and 50 μm or less can be obtained at a low cost, and thus are suitable. Moreover, as a zinc compound used as a raw material, zinc acetate is suitable because it can be obtained at a low cost and is easy to handle.

  The reason for using acetic acid as a raw material is that fine particles of zinc oxide are not formed even when heated with an organic acid other than acetic acid, and the reaction does not proceed with the zinc complex composed of the organic acid.

  As glycols used as raw materials, ethylene glycol, propylene glycol, trimethylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6- Alkylene glycols such as hexanediol, 1,8-octanediol, 1,10-decanediol, pinacol, diethylene glycol, triethylene glycol, cyclopentane-1,2-diol, cyclohexane-1,2-diol, cyclohexane-1 , 4-diol, alicyclic glycols, propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, 3-methyl 3-methoxybutanol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, triethylene glycol monomethyl ether, derivatives of such glycols monoethers and monoesters such as ethylene glycol monoacetate, and the like. Among these, ethylene glycol, propylene glycol, 1,3-propanediol, diethylene glycol, 1,3-butanediol or triethylene glycol is particularly preferable. By using the glycol compound of the above type, the shape of the obtained zinc oxide fine particles can be controlled to various shapes such as a granular shape, a scale shape, a rod shape, and a polygonal shape.

  The mixing ratio of the zinc compound, acetic acid, glycol and water is such that when the entire mixture is 100% by mass, the ratio of zinc compound is 0.1 to 20% by mass, the ratio of acetic acid is 1 to 30% by mass, and the ratio of glycol Is preferably prepared so that the proportion of water is in the range of 0.1 to 5% by mass. Among these, when the whole mixture is 100 mass%, the ratio of zinc compound is 0.1 to 10 mass%, the ratio of acetic acid is 5 to 20 mass%, the ratio of glycol is 75 to 95 mass%, and the ratio of water is It is particularly preferable to prepare so as to be in the range of 0.1 to 5% by mass. When the ratio of the zinc compound is within the range of 0.1 to 20% by mass, the productivity is poor when the ratio is less than the lower limit, and when the ratio exceeds the upper limit, the zinc compound is difficult to dissolve in the solvent glycol, This is because productivity deteriorates. The ratio of acetic acid within the range of 5 to 30% by mass is that the zinc compound is difficult to dissolve if it is less than the lower limit, and if the upper limit is exceeded, the pH of the mixed solution becomes too low, and zinc oxide It is because it becomes easy to melt | dissolve and a yield worsens. Furthermore, the water content in the range of 0.1 to 5% by mass is less than the lower limit value, the zinc compound is difficult to dissolve, the productivity is poor, and the zinc oxide produced when the upper limit value is exceeded. This is because the particle size of the particles becomes too large or the reaction becomes difficult to proceed.

The heating and holding temperature of the mixture obtained by mixing the zinc compound, acetic acid, glycol and water was set to 50 to 200 ° C. The reaction did not proceed at a temperature lower than 50 ° C. This is because a product is formed. Among these, a preferable heating and holding temperature is 100 to 180 ° C. The heating and holding time by microwave irradiation is preferably 1 to 60 minutes. This is because if the heating and holding time by microwave irradiation is less than 1 minute, the reaction hardly proceeds, and if it exceeds 60 minutes, a large amount of by-products are generated or productivity is deteriorated. Moreover, it is preferable that the microwave irradiated at this time has the frequency in the range of 890-940 MHz, 2400-2500 MHz, or 5725-5875 MHz. The microwave irradiation intensity is preferably in the range of 0.005 to 20 W / cm ³ . The irradiation intensity of the microwave is too time consuming to raise the temperature to the holding temperature is less than 0.005 W / cm ^3, such as bumping excessively temperature rises exceeds 20W / cm ³ occurs, the temperature control is difficult Because.

  A method for producing the zinc oxide fine particles of the present invention will be described.

  First, glycol and a zinc compound are put into a flask in this order, and acetic acid and water if necessary are added and mixed to prepare a mixed solution. Further, when an additive for modifying the surface of the generated zinc oxide fine particles is added, a more stable dispersion can be obtained. The additive is not particularly limited as long as it modifies the surface of zinc oxide, but a polymer dispersant, Si, Ti, Al-based coupling agent and the like are particularly preferable. Next, the prepared liquid mixture was stirred with a magnetic stirrer, irradiated with microwaves while refluxed, and heated to a temperature of 50 to 200 ° C. over 0.5 to 20 minutes. Continue to irradiate microwaves for 1-60 minutes to maintain a temperature of 0C. When the temperature reaches 50 to 200 ° C., the mixed liquid in the flask reacts and white particles are precipitated in the reaction liquid. Then let it cool naturally.

  The obtained white reaction liquid can be used as a very stable zinc oxide fine particle dispersion as it is, but when only the zinc oxide fine particles are collected, it can be collected by the following method. First, a white precipitate is separated from a reaction liquid by centrifuging the obtained white reaction liquid at 500-1500 G for 1 to 5 hours. Since the separated white precipitate contains glycol and by-products, the white precipitate is redispersed in a solvent such as ethanol, acetone or water, and the dispersion is centrifuged to obtain a dispersion. The white precipitate is washed by repeating the process of separating the white precipitate from a plurality of times. Next, the washed white precipitate is vacuum-dried at 25 to 60 ° C. to obtain desired zinc oxide fine particles. Thus, since it does not pass through a multistep process, zinc oxide microparticles | fine-particles can be obtained with high productivity. In addition, since alkali metal is not used as a production raw material, alkali-free zinc oxide fine particles can be obtained.

  When the zinc oxide fine particles produced by the production method of the present invention are measured by X-ray diffraction, if the half-width of the maximum peak in the X-ray diffraction pattern obtained by the measurement is 0.5 degrees or less, the crystallinity is It can be confirmed that zinc oxide fine particles that are high and can be applied to ultraviolet light sources and ultraviolet lasers that have lost green light emission have been obtained, but further, acetic acid and glycol or their additives are modified on the surface of the zinc oxide fine particles, By compensating for defects on the surface of the zinc oxide fine particles, green light emission derived from the defects can be further eliminated.

  The zinc oxide fine particles having an average particle diameter of 200 nm or less produced by the production method of the present invention are at least selected from the group consisting of spherical, needle-like, plate-like, polygonal, polygonal pyramid, polygonal and rod-like. It can have one shape. Among these, the generated zinc oxide fine particles include particles having at least one shape selected from the group consisting of needle shape, plate shape, polygonal shape, polygonal pyramid shape, polygonal shape and rod shape in addition to spherical particles. It is composed of two or more types of particle shapes.

The zinc oxide fine particles produced by the production method of the present invention are fine particles having an average particle diameter of 200 nm or less obtained by the production method of the present invention described above, and are obtained by measurement when the fine particles are measured by X-ray diffraction. The full width at half maximum of the maximum peak in the obtained X-ray diffraction pattern is 0.5 degrees or less. If the average particle diameter obtained by the above production method is 200 nm or less, and the half-width of the maximum peak in the X-ray diffraction pattern is 0.5 degrees or less, the crystallinity is high and the emission is dominant in the ultraviolet region. Has a wavelength and excellent dispersibility.

Method for producing a dispersion according to the present invention comprises the steps of obtaining a zinc oxide fine particles by the process of the present invention described above, a step of Ru is dispersed zinc oxide particles in a dispersion medium. The dispersion obtained by the production method of the present invention has excellent dispersibility. Alcohol is used as the dispersion medium. Although it does not specifically limit as said alcohol, For example, aliphatic monohydric alcohols, such as methanol, ethanol, isopropyl alcohol, n-butanol, t-butyl alcohol, stearyl alcohol, ethylene glycol, propylene glycol, 1, 3-propane Diol, trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, pinacol, Alkylene glycols such as diethylene glycol and triethylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl And derivatives of monoethers and monoesters of the above glycols such as ether, 3-methyl-3-methoxybutanol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, triethylene glycol monomethyl ether, and ethylene glycol monoacetate. . These alcohols may be used alone or in combination of two or more. In addition, this dispersion has a zinc oxide fine film concentration of 0.1 to 50% by mass in order to sufficiently secure the thickness of the zinc oxide film using the dispersion and the zinc oxide content in the case of coating. It is preferable to prepare so that it may exist in the range .
In particular, when the zinc oxide fine particles include at least a triangular pyramid shape and a spherical shape and all the shapes constituting the fine particles are 100%, the proportion of the triangular pyramid shape included is in the range of 10 to 40%. Some dispersions are dispersions with less green light emission from defects and higher emission intensity in the ultraviolet region. Further, in this dispersion, when the zinc oxide fine particles include at least a rod-like shape having an aspect ratio of 3 to 10, and the total shape constituting the fine particles is 100%, the ratio of the rod-like shape is 80 to 99. % Is preferable.

The dispersion obtained by the production method of the present invention has excellent effects that the green light emission derived from defects disappears and the light emission intensity in the ultraviolet region is strong. It can be used as a luminescent material.

  In addition, the zinc oxide fine particles obtained by the production method of the present invention can be obtained with high productivity, and the dispersion in which the zinc oxide fine particles are dispersed is used as an ultraviolet light emitter material, thereby reducing the production cost. It can be a light source or an ultraviolet laser.

Next, examples of the present invention will be described in detail together with comparative examples.
<Example 1>

First, as shown in Table 1 below, zinc oxide coarse particles having an average particle diameter of 0.5 μm were prepared as a zinc compound, and ethylene glycol was prepared as a solvent. Acetic acid and water were also prepared. Next, 300 g of ethylene glycol and 15 g of zinc oxide coarse particles were sequentially added to the flask, and acetic acid and water were further added and mixed to prepare a mixed solution. Subsequently, the prepared mixed liquid was stirred with a magnetic stirrer in an oil bath, and irradiated with microwaves having a frequency of 2.45 GHz and an irradiation intensity of 5 W / cm ³ until the temperature reached 150 ° C. over about 5 minutes. The temperature was raised. During this heating, when the temperature reached 145 ° C., white particles were precipitated in the flask. Thereafter, microwaves with an irradiation intensity of 5 W / cm ³ were continuously irradiated so as to maintain a temperature of 150 ° C., held for 20 minutes, and then allowed to cool naturally. Next, the white reaction liquid obtained was centrifuged at 1000 G for 5 hours to separate a white precipitate from the reaction liquid. Furthermore, the separated white precipitate was re-dispersed in ethanol, the dispersion was centrifuged, and the process of separating the white precipitate from the dispersion was repeated three times to wash the white precipitate. Finally, the washed white precipitate was vacuum dried at 50 ° C. to obtain the desired white powder.

  The obtained white powder was measured by XRD (X-ray diffraction). The obtained X-ray diffraction pattern is shown in FIG. From FIG. 1, it was confirmed that the measurement peak position completely coincided with hexagonal zinc oxide, and the obtained powder was zinc oxide powder. In addition, the half-value width of the diffraction peak due to the (101) plane, which is the maximum peak in the X-ray diffraction pattern obtained by this measurement, was very narrow at 0.27 degrees, indicating that the particles were highly crystalline zinc oxide particles. . Moreover, when TEM (transmission electron microscope) observation of the obtained white powder was performed, triangular particles having a side of about 90 nm were partially observed in spherical particles having a particle size of 40 nm. Moreover, when SEM (scanning electron microscope) observation of the obtained white powder was performed, it was confirmed that the triangular-shaped particle | grains seen by TEM observation are triangular pyramid-shaped particles. The results are shown in Table 2 below.

<Example 2>
As shown in Table 1 below, white powder was obtained in the same manner as in Example 1 except that propylene glycol was used instead of ethylene glycol as the solvent.

  When the obtained white powder was subjected to XRD measurement, the measurement peak position completely coincided with hexagonal zinc oxide, and it was confirmed that the obtained powder was zinc oxide powder. Further, the half-value width of the diffraction peak due to the (101) plane, which is the maximum peak in the X-ray diffraction pattern obtained by this measurement, was very narrow at 0.32 degrees, and it was found that the particles were highly crystalline zinc oxide particles. . Further, when TEM observation and SEM observation of the obtained white powder were performed, some of the scaly particles having a side of about 40 nm were observed in spherical particles having a particle diameter of 20 nm. The results are shown in Table 2 below.

<Example 3>
As shown in Table 1 below, white powder was obtained in the same manner as in Example 1 except that 1,3-propanediol was used as the solvent instead of ethylene glycol.

  When the obtained white powder was subjected to XRD measurement, the measurement peak position completely coincided with hexagonal zinc oxide, and it was confirmed that the obtained powder was zinc oxide powder. In addition, the half-value width of the diffraction peak due to the (101) plane, which is the maximum peak in the X-ray diffraction pattern obtained by this measurement, was very narrow at 0.23 degrees, indicating that the particles were highly crystalline zinc oxide particles. . Moreover, when TEM observation and SEM observation of the obtained white powder were performed, spherical particles having a particle size of 30 nm were confirmed. The results are shown in Table 2 below.

<Example 4>
As shown in Table 1 below, white powder was obtained in the same manner as in Example 1 except that diethylene glycol was used instead of ethylene glycol as the solvent.

When the obtained white powder was subjected to XRD measurement, the measurement peak position completely coincided with hexagonal zinc oxide, and it was confirmed that the obtained powder was zinc oxide powder. Further, the half-value width of the diffraction peak due to the (101) plane, which is the maximum peak in the X-ray diffraction pattern obtained by this measurement, was very narrow at 0.25 degrees, and it was found that the particles were highly crystalline zinc oxide particles. . Further, when TEM observation and SEM observation were performed on the obtained white powder, rod-shaped particles having a major axis of 80 nm and a minor axis of 30 nm were confirmed. The results are shown in Table 2 below.
<Example 5>

  As shown in Table 1 below, white powder was obtained in the same manner as in Example 1 except that 1,3-butanediol was used instead of ethylene glycol as the solvent.

When the obtained white powder was subjected to XRD measurement, the measurement peak position completely coincided with hexagonal zinc oxide, and it was confirmed that the obtained powder was zinc oxide powder. Further, the half-value width of the diffraction peak due to the (101) plane, which is the maximum peak in the X-ray diffraction pattern obtained by this measurement, was very narrow at 0.22 degrees, and it was found that the particles were highly crystalline zinc oxide particles. . Moreover, when TEM observation and SEM observation of the obtained white powder were performed, spherical particles having a particle size of 30 nm were confirmed. The results are shown in Table 2 below.

<Example 6>
As shown in Table 1 below, in the same manner as in Example 1 except that 1,3-propanediol was used instead of ethylene glycol as a solvent and that the heating and holding time by microwave irradiation was 5 minutes. A white powder was obtained.

  When the obtained white powder was subjected to XRD measurement, the measurement peak position completely coincided with hexagonal zinc oxide, and it was confirmed that the obtained powder was zinc oxide powder. Further, the half-value width of the diffraction peak due to the (101) plane, which is the maximum peak in the X-ray diffraction pattern obtained by this measurement, was very narrow at 0.25 degrees, and it was found that the particles were highly crystalline zinc oxide particles. . Moreover, when TEM observation and SEM observation of the obtained white powder were performed, spherical particles having a particle diameter of 40 nm were confirmed. The results are shown in Table 2 below.

<Example 7>
As shown in Table 1 below, the same method as in Example 1 was used except that 1,3-propanediol was used instead of ethylene glycol as a solvent and that the heating and holding time by microwave irradiation was 40 minutes. A white powder was obtained.

When the obtained white powder was subjected to XRD measurement, the measurement peak position completely coincided with hexagonal zinc oxide, and it was confirmed that the obtained powder was zinc oxide powder. Further, the half-value width of the diffraction peak due to the (101) plane, which is the maximum peak in the X-ray diffraction pattern obtained by this measurement, was very narrow at 0.21 degrees, and it was found that the particles were highly crystalline zinc oxide particles. . Moreover, when TEM observation and SEM observation of the obtained white powder were performed, spherical particles having a particle diameter of 25 nm were confirmed. The results are shown in Table 2 below.

<Example 8>
As shown in Table 1 below, the same method as in Example 1 was used except that 1,3-propanediol was used instead of ethylene glycol as the solvent and that the heating and holding time by microwave irradiation was 60 minutes. A white powder was obtained.

  When the obtained white powder was subjected to XRD measurement, the measurement peak position completely coincided with hexagonal zinc oxide, and it was confirmed that the obtained powder was zinc oxide powder. In addition, the half-value width of the diffraction peak due to the (101) plane, which is the maximum peak in the X-ray diffraction pattern obtained by this measurement, was very narrow at 0.20 degrees, indicating that the particles were highly crystalline zinc oxide particles. . Moreover, when TEM observation and SEM observation of the obtained white powder were performed, spherical particles having a particle diameter of 25 nm were confirmed. The results are shown in Table 2 below.

<Comparative Example 1>
First, as shown in Table 1 below, zinc oxide coarse particles having an average particle diameter of 0.5 μm were prepared as a zinc compound, methanol as a solvent, and potassium hydroxide as an alkali. Acetic acid and water were also prepared. Next, an appropriate amount of methanol and acetic acid are introduced into the flask in this order, and 5 g of ion-exchanged water and 21.5 g of zinc oxide coarse particles are added and heated to 60 ° C. while refluxing. It was dripped at the zinc oxide methanol solution in the flask heated at 60 degreeC. Immediately after the addition, the reaction solution became cloudy. Next, the obtained white reaction liquid was centrifuged at 500 G for 30 minutes to separate a white precipitate from the reaction liquid. Furthermore, the separated white precipitate was re-dispersed in ethanol, the dispersion was centrifuged, and the process of separating the white precipitate from the dispersion was repeated three times to wash the white precipitate. Finally, the washed white precipitate was vacuum dried at 50 ° C. to obtain the desired white powder.

  The obtained white powder was subjected to XRD measurement. The obtained X-ray diffraction pattern is shown in FIG. From FIG. 2, the measurement peak position completely coincided with hexagonal zinc oxide, and it was confirmed that the obtained powder was zinc oxide powder. However, the peak was broad compared to the peak of Example 1. It was found that the full width at half maximum of the diffraction peak due to the (101) plane, which is the maximum peak in the X-ray diffraction pattern obtained by this measurement, was 1.1 degrees, which is a zinc oxide particle having low crystallinity. Moreover, when TEM observation and SEM observation of the obtained white powder were performed, spherical particles having a particle diameter of 10 nm were confirmed. The results are shown in Table 2 below.

<Comparative example 2>
As shown in Table 1 below, an attempt was made to synthesize zinc oxide fine particles by the same method as in Example 3 except that formic acid was used instead of acetic acid. Zinc oxide fine particles were not generated. The results are shown in Table 2 below.

<Comparative Example 3>
As shown in Table 1 below, synthesis of zinc oxide fine particles was attempted by the same method as in Example 3 except that 2-ethylhexanoic acid was used instead of acetic acid. The compound of hexane and zinc was present as it was, and zinc oxide fine particles were not generated. The results are shown in Table 2 below.

<Comparative example 4>
As shown in Table 1 below, synthesis of zinc oxide fine particles was attempted by the same method as in Example 3 except that propionic acid was used instead of acetic acid. The compound remained as it was, and no zinc oxide fine particles were generated. The results are shown in Table 2 below.

<Comparative Example 5>
As shown in Table 1 below, a white powder was obtained in the same manner as in Example 1 except that 2-n-butoxyethanol was used instead of glycol as the solvent.

  The obtained white powder was subjected to XRD measurement. The obtained X-ray diffraction pattern is shown in FIG. From FIG. 3, the measurement peak position completely coincided with hexagonal zinc oxide, and it was confirmed that the obtained powder was zinc oxide powder. However, the full width at half maximum of the diffraction peak due to the (101) plane, which is the maximum peak in the X-ray diffraction pattern obtained by this measurement, was as wide as 0.59 degrees, indicating that the particles were inferior in crystallinity. Moreover, when TEM observation and SEM observation of the obtained white powder were performed, spherical particles having a particle diameter of 5 nm were confirmed. The results are shown in Table 2 below.

<Comparative Example 6>
As shown in Table 1 below, white powder was obtained in the same manner as in Example 1 except that ethanol was used instead of glycol as the solvent.

  The obtained white powder was subjected to XRD measurement. The obtained X-ray diffraction pattern is shown in FIG. From FIG. 4, the measurement peak position completely coincided with hexagonal zinc oxide, and it was confirmed that the obtained powder was zinc oxide powder. However, the half-value width of the diffraction peak due to the (101) plane, which is the maximum peak in the X-ray diffraction pattern obtained by this measurement, was as wide as 0.72 degrees, indicating that the particles were inferior in crystallinity. Moreover, when TEM observation and SEM observation of the obtained white powder were performed, spherical particles having a particle diameter of 15 nm were confirmed. The results are shown in Table 2 below.

<Comparative Example 7>
As shown in Table 1 below, in the same manner as in Example 1 except that 1,3-propanediol was used instead of ethylene glycol as a solvent and that the heating and holding time by microwave irradiation was 120 minutes. A white powder was obtained.

  When the obtained white powder was subjected to XRD measurement, the measurement peak position completely coincided with hexagonal zinc oxide, and it was confirmed that the obtained powder was zinc oxide powder. In addition, the half-value width of the diffraction peak due to the (101) plane, which is the maximum peak in the X-ray diffraction pattern obtained by this measurement, was very narrow at 0.20 degrees, indicating that the particles were highly crystalline zinc oxide particles. . Moreover, when TEM observation and SEM observation of the obtained white powder were performed, spherical particles having a particle diameter of 25 nm were confirmed. The results are shown in Table 2 below.

＜実施例９＞
実施例１で得られた酸化亜鉛微粒子を濃度が１質量％となるようにエタノールに添加し、この添加液に超音波を約２０分ほどかけて微粒子を分散させることにより、酸化亜鉛微粒子分散液を得た。

<Example 9>
The zinc oxide fine particles obtained in Example 1 were added to ethanol so as to have a concentration of 1% by mass, and the fine particles were dispersed in this additive solution by applying ultrasonic waves for about 20 minutes. Got.

<Comparison test 1>
The dispersion of the zinc oxide fine particles obtained in Example 9 was allowed to stand, and the dispersibility of the dispersion was evaluated by the presence or absence of the precipitate generated in the dispersion. At that time, the precipitate remained in the dispersion even after 2 weeks. It was confirmed that the dispersion was extremely excellent in dispersibility.

<Comparison test 2>
Fluorescence measurement was performed using the zinc oxide fine particle dispersion obtained in Example 9. The result is shown in FIG.

  As is clear from FIG. 5, in the emission and absorption spectra, no green emission peak was observed between wavelengths of 400 to 600 nm, and the emission peak wavelength was only ultraviolet emission near 380 nm.

The figure which shows the X-ray-diffraction pattern of the zinc oxide microparticles | fine-particles obtained in Example 1. FIG. The figure which shows the X-ray-diffraction pattern of the zinc oxide microparticles | fine-particles obtained by the comparative example 1. The figure which shows the X-ray-diffraction pattern of the zinc oxide microparticles | fine-particles obtained by the comparative example 5. The figure which shows the X-ray-diffraction pattern of the zinc oxide microparticles | fine-particles obtained by the comparative example 6. FIG. 9 is a graph showing light emission and absorption spectra in the zinc oxide fine particle dispersion of Example 9.

Claims (17)

A zinc compound, acetic acid and glycol are mixed to prepare a mixed solution, and the prepared mixed solution is irradiated with microwaves and held at a temperature of 50 to 200 ° C., whereby the average particle size is 200 nm or less , A method for producing zinc oxide fine particles, wherein , when measured by X-ray diffraction, zinc oxide fine particles having a half-value width of a maximum peak in an X-ray diffraction pattern obtained by measurement of 0.5 degrees or less are generated.   The method for producing fine zinc oxide particles according to claim 1, wherein the zinc compound used as a raw material is coarse zinc oxide particles having a particle size of from submicron to 50 µm.   The method for producing fine zinc oxide particles according to claim 1, wherein the zinc compound used as a raw material is zinc acetate.   The method for producing fine zinc oxide particles according to claim 1, wherein the glycol used as a raw material is ethylene glycol, propylene glycol, 1,3-propanediol, diethylene glycol, 1,3-butanediol, or triethylene glycol.   The method for producing zinc oxide fine particles according to any one of claims 1 to 4, wherein the microwave frequency is a frequency within a range of 890 to 940 MHz, 2400 to 2500 MHz, or 5725 to 5875 MHz.   The method for producing zinc oxide fine particles according to any one of claims 1 to 5, wherein the temperature rise time to the heating holding temperature by microwave irradiation is 0.5 to 20 minutes.   The method for producing zinc oxide fine particles according to any one of claims 1 to 6, wherein a heating and holding time by microwave irradiation is 1 to 60 minutes. Were generated zinc oxide fine particles, spherical, acicular, or plate-like, polygonal, polygonal pyramid, claims 1 particles having at least one shape selected from the group consisting of polyhedral shape and rod-7 A method for producing zinc oxide fine particles according to claim 1. The generated zinc oxide fine particles include particles having at least one shape selected from the group consisting of a plate shape, a polygonal shape, a polygonal pyramid shape, a polygonal shape and a rod shape in addition to the spherical particles. The method for producing zinc oxide fine particles according to any one of claims 1 to 7, comprising a particle shape. Irradiating the mixed solution with microwaves, and then separating the white precipitate from the reaction solution by centrifuging the obtained reaction solution;
Re-dispersing the separated white precipitate in a solvent and centrifuging the dispersion, repeating the washing of the white precipitate a plurality of times;
Vacuum drying the washed white precipitate at 25-60 ° C;
The method for producing zinc oxide fine particles according to claim 1, comprising: A step of producing zinc oxide fine particles by the production method according to any one of claims 1 to 10,
Dispersing the zinc oxide fine particles in a dispersion medium. The zinc oxide fine particles include at least both a triangular pyramid shape and a spherical shape,
The method for producing a dispersion according to claim 11, wherein the ratio of the triangular pyramid shape is in the range of 10 to 40% when all the shapes constituting the fine particles are 100%. The zinc oxide fine particles include at least a rod-like shape having an aspect ratio of 3 to 10,
The method for producing a dispersion according to claim 11, wherein the ratio of the rod-like shape is in the range of 80 to 99% when all the shapes constituting the fine particles are 100%. A step of obtaining a dispersion by the production method according to any one of claims 11 to 13,
And a step of forming a film using the dispersion.   The manufacturing method of fluorescent substance including the process of obtaining a zinc oxide film with the manufacturing method of Claim 14. A step of obtaining a zinc oxide fine particle dispersion by the production method according to any one of claims 11 to 13,
And a step of obtaining an ultraviolet light source using the zinc oxide fine particle dispersion as an ultraviolet light emitter material. A step of obtaining a zinc oxide fine particle dispersion by the production method according to any one of claims 11 to 13,
And a step of obtaining an ultraviolet laser using the zinc oxide fine particle dispersion as an ultraviolet light emitter material.

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