JPS6048450B2 - Production method of zinc sulfide precipitate - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for producing zinc sulfide precipitate.

Zinc sulfide precipitate is important as a raw material for fluorescent substances, and its purity and particle state directly influence the luminescent performance and particle size distribution, which are the central properties of fluorescent substances.

Usually, the manufacturing method of zinc sulfide precipitate is zinc sulfate, zinc chloride,
It is obtained by passing hydrogen sulfide gas into an aqueous solution containing zinc ions such as zinc nitrate to complete the reaction, thoroughly washing with water, and then drying. Various attempts have been made to change and improve the state of precipitated particles, such as changing the pH and temperature during the reaction and adding different types of water-soluble substances (for example, R, A, Brown, Electro
chem, Technol, 6246 (1968)) There is still room for improvement. What is meant by improvement of the particle state? For example, in the zinc sulfide precipitate obtained by the normal method described above, the agglomeration state of the fine particle precipitate is irregular, as shown in the photograph in Figure 1, and the agglomerated particles The particle size distribution of the group becomes broad.

The particle size distribution of this precipitate determined by the Coulter Counter method is as shown in Figure 5a. The purpose of the present invention is to improve the particle condition by making the precipitated particles as uniform as possible and having a sharp particle size distribution. The present invention provides a method. In a wet method for producing zinc sulfide by passing hydrogen sulfide gas into a zinc ion solution, the present inventors introduced colloidal zinc sulfide with a uniform crystal particle size into a zinc ion solution before starting the precipitation reaction. They discovered that when dispersed, this serves as the core function of the precipitation reaction, and that the reaction proceeds uniformly around this. The first feature of the production method of the present invention is to produce precipitation nuclei of colloidal crystal particles with uniform particle diameters by adding an alkaline aqueous solution (for example, aqueous ammonia) to an aqueous solution containing zinc ions. The method is to first form a colloidal precipitate of zinc chloride hydroxide and then convert it into colloidal zinc sulfide by passing hydrogen sulfide gas through it. FIG. 3 shows a photograph of such a zinc sulfide precipitate nucleus observed with an electron microscope at a magnification of 205 times, and it is observed as a single crystal '5 particle whose particle size is controlled within the range of 100 to 300 Λ particle size. Therefore, the present invention has come to the conclusion that this precipitation nucleus is excellent in the nuclear function of the precipitation reaction. When hydrogen sulfide gas is passed through a zinc ion solution containing such precipitated nuclei, the reaction proceeds rapidly and particle growth begins. When the sulfidation reaction of zinc ions in the solution is completed,
When the precipitate is left to settle, the supernatant liquid is removed, a zinc ion solution is added again, and hydrogen sulfide gas is passed through the solution, the sulfurization reaction continues and the growth of particles continues. The second feature of the present invention is to repeatedly inject zinc ion solution into the initial precipitated state, which is a uniform particle precipitate nucleus, to continue the sulfidation reaction and adjust the growth of precipitated particles as desired. things become possible. The growth of precipitated particles mentioned here does not necessarily mean growth as a single crystal, but also refers to particle growth due to the aggregation of minute crystal particles. This is considered to be a particle size growth phenomenon associated with agglomeration of microparticles. When zinc sulfate is used as the zinc ion source, FIG. 6 shows how the precipitate particle size grows with the amount of zinc ions injected. The amount of precipitate nuclei used in this case was equivalent to 0.7 m01 of zinc sulfide, and the details will be described in the Examples. The plain method (aeration method) was used to measure the average particle size. Zinc io. Optical micrographs of precipitated particles obtained at each stage of injection are shown in FIG. It can be seen that the particle size is extremely uniform and that the particle growth is progressing uniformly. Such well-sized zinc sulfide particles do not disintegrate even when an activator is added and fired, and have the advantage of providing an excellent fluorescent surface such as uniformity and densification of the two films. Example 10e flask with 1.10 mO1 concentration of zinc sulfate 640
Add mι and 3000 ml of pure water and gradually add 923 ml of concentrated ammonia water while stirring.

Inside the system, a cloudy colloidal precipitate of zinc hydroxide was generated.
After stirring the powder, hydrogen sulfide gas is introduced at a flow rate of 1.51/min for 1 hour, and the cloudy precipitate is converted into colloidal zinc sulfide. The particle size is controlled within the range of 100 to 300.3. Ru. Stop the reaction, stop stirring, let it stand, and when the supernatant becomes clear, add 2000ml using a siphon.
Remove the equivalent and add 1.10m01 concentration of zinc sulfate to 5000
ml was added, and hydrogen sulfide was passed at a flow rate of 1.51/min for about 5 hours while stirring until the reaction was completed. At this point, the zinc sulfide particle size is about 0.5μ. After the reaction was stopped and left to stand, 5000 mι of supernatant was removed and 500 mι of new zinc sulfate was added.
Add 0 mι and proceed with the reaction at the same time as above. By repeating this operation, particle growth of the zinc sulfide precipitate progresses gradually, and as shown in FIG. 6, the average particle size can be controlled arbitrarily by changing the amount of zinc sulfate injected. When the last reaction is completed, wash the gradient with pure water and repeat at 120℃ for 1 time.
After drying for a while, zinc sulfide powder with uniform particles can be obtained.
When the amount of zinc sulfate injected was 35 m01, the average particle size of the precipitate was 2.2 μm, and an electron microscope photograph thereof is shown in FIG. The particle size distribution determined by the Coulter method is shown in FIG. 5b. In addition to zinc sulfate, zinc chloride, zinc nitrate, and the like are also suitable as water-soluble materials containing zinc ions that are applicable to the present invention, but are not limited thereto. Brief explanation of the drawings Figure 1 is 1.10
Electron micrograph (3000x) showing conventional zinc sulfide precipitation obtained by completing the sulfidation reaction by passing hydrogen sulfide into zinc sulfide at m01 concentration. Figure 2 shows zinc sulfide produced according to an embodiment of the present invention. Figure 3 is an electron micrograph showing precipitation (30 AM), Figure 3 is an electron micrograph (20,000 AM) showing zinc sulfide precipitate nuclei used in the production method of the present invention, and Figure 4 is an electron micrograph (20,000 AM) showing precipitation. These are optical micrographs (10x magnification) showing the zinc sulfide precipitate obtained in the manufacturing process. 1 to 4 indicate that the MOL concentration of zinc sulfate is 1.11 m01 equivalent, 2.3 m01 equivalent, 3.72 m01 equivalent, 4,102 m01 equivalent. Figure 5 shows the particle size distribution of zinc sulfide measured by the Coulter counter method; The zinc sulfide precipitates obtained according to the examples are shown, and FIG. It is a figure showing the relationship with the average particle size of a precipitate.

Claims (1)

[Claims] 1 Add an alkaline solution to an aqueous solution containing zinc ions to make zinc hydroxide, and add hydrogen sulfide to this to add 100 to 3
A step of forming precipitation nuclei of zinc sulfide crystals of 00 Å, a step of adding a zinc ion solution to this and precipitating zinc sulfide particles around the precipitation nuclei through hydrogen sulfide, and a step of discharging the supernatant liquid after the reaction of zinc ions has been completed. A method for producing zinc sulfide precipitate, comprising the steps of removing the zinc ion solution, adding a zinc ion solution, and repeating the precipitation of zinc sulfide particles through hydrogen sulfide.