Dispersion method of granulated microspheres obtained by spray drying method and application thereof

Abstract

The invention discloses a dispersion method of granulated microspheres obtained by a spray drying method and application thereof, and relates to the technical field of granulated microspheres, the method comprises the following steps: placing granulated microspheres in a dispersant aqueous solution, and standing to obtain a suspension; transferring the suspension into an ultrasonic processor for ultrasonic treatment to obtain an ultrasonic suspension; transferring the ultrasonic suspension into a freezer, freezing into blocks, then taking out, putting into a lubricant aqueous solution, unfreezing, then filtering, separating filtrate from a filter material, transferring the filter material into the freezer again, freezing into blocks, then taking out, putting into the filtrate, and unfreezing to obtain an unfrozen suspension; filtering or centrifugally separating the unfrozen suspension, collecting a solid isolate, washing the solid isolate with deionized water, and drying to obtain a powder material; the surface structure of the powder material dispersed by the method is not damaged, and powder particles can be dispersed more sufficiently.

Description

Technical Field

[0001] The invention relates to the technical field of granulated microspheres, and in particular to a dispersion method of granulated microspheres obtained by a spray drying method and application thereof. Background Art

[0002] Precursor slurry drying in the field of ceramic powders is generally carried out by spray drying. The principle is to atomize the slurry first. After the atomized slurry particles come into contact with the hot air in the cavity by convection, the water evaporates quickly and the powder particles fall into the collection device, thereby achieving the purpose of drying and collection.

[0003] During the spray drying process, there are several reasons, including:

[0004] 1. Attraction between solid particles: including van der Waals force, electrostatic force and magnetic field force;

[0005] 2. Liquid bridging and capillary forces also generate attractive pressure between particles, forming connections;

[0006] 3. Under specific temperature conditions, the connections formed by molecular diffusion at the contact points between particles enhance the stability of the particles.

[0007] The above reasons combined result in the powder obtained by drying to exist in the form of granulated microspheres. Granulated microspheres are composed of countless small primary powder particles tightly assembled due to the binding force. Therefore, the granulated microspheres will not be easily dispersed, which will indirectly lead to uneven heating of the powder particles during the subsequent calcination treatment of the granulated microspheres, resulting in irregular crystal growth and severe hard agglomeration, which in turn affects the subsequent powder performance.

[0008] In the prior art, the granulated microspheres can be dispersed and crushed by feeding them into a stirrer for mechanical stirring. However, during the stirring process, the stirring intensity and power are difficult to control accurately. If the stirring intensity is too large, the surface structure of the powder particles will be damaged. If the stirring intensity is too small, it will be difficult to achieve a good dispersion effect. In addition, the powder particles after dispersion are prone to reagglomeration, which will have an adverse effect on subsequent use. Summary of the invention

[0009] The purpose of the present invention is to provide a dispersion method of granulated microspheres obtained by spray drying and its application, so as to solve the following technical problems:

[0010] How to disperse granulated microspheres without damaging the powder particle structure?

[0011] The purpose of the present invention can be achieved through the following technical solutions:

[0012] In a first aspect, the present invention discloses a method for dispersing granulated microspheres obtained by a spray drying method, comprising the following steps:

[0013] S1. Place the granulated microspheres in a dispersant aqueous solution and let stand for 20-30 minutes to partially disperse the granulated microspheres to obtain a suspension;

[0014] S2. The suspension is transferred to an ultrasonic processor for ultrasonic treatment to further disperse the granulated microspheres to obtain an ultrasonic suspension; during the ultrasonic process, a stirring paddle can be used for slow stirring to ensure the suspension state of the granulated microspheres in the suspension while avoiding damage to the surface structure of the granulated microspheres;

[0015] S3, transfer the ultrasonic suspension to a freezer, freeze it to below -20°C within 2 hours, and keep it for 20-24 hours, so that the ultrasonic suspension is frozen into blocks. During this process, the water inside the granulated microspheres that have not yet been dispersed will freeze and expand, and the stress generated will aggravate the separation of powder particles, thereby reducing the binding force between the powder particles; then take it out and place it in a lubricant aqueous solution at 40-50°C for thawing for 2-3 hours, remove the ice between the powder particles in the spherical particles, and convert it into water and dissolve it in the lubricant aqueous solution. At the same time, the powder particles are automatically separated to achieve the purpose of dispersion, and then filter it to separate the filtrate and the filter material, transfer the filter material to the freezer again, freeze it to below -20°C within 2 hours, and keep it for 20-24 hours, then take it out and place it in a filtrate at 40-50°C for thawing for 2-3 hours to obtain a thawed suspension;

[0016] S4. Filter or centrifuge the thawed suspension, collect the solid separation, wash the solid separation 2-3 times with deionized water to remove the dispersant and part of the lubricant remaining on the surface of the granulated microspheres, and finally dry to obtain a powder material.

[0017] Furthermore, in step S1, the dispersant aqueous solution is a polyethylene glycol aqueous solution or a sodium polyacrylate aqueous solution.

[0018] Furthermore, the mass fraction of the dispersant in the dispersant aqueous solution is 2% to 5%;

[0019] Preferably, the mass fraction of the dispersant in the dispersant aqueous solution is 3%.

[0020] Further, in step S1, the dosage ratio of the granulated microspheres to the dispersant aqueous solution is 1 g: (2-5) mL;

[0021] Preferably, the dosage ratio of the granulated microspheres to the dispersant aqueous solution is 1 g:3 mL.

[0022] Further, in step S2, the method of performing ultrasonic treatment is: ultrasonic treatment at 20-40kHz for 10-20min;

[0023] Preferably, the ultrasonic treatment method is: ultrasonic treatment at 30 kHz for 15 min.

[0024] Furthermore, in step S3, the lubricant aqueous solution is any one of a polyol aqueous solution, a glycerol aqueous solution, and a silicone aqueous solution; the use of the lubricant aqueous solution can form a lubricating film layer on the surface of the dispersed powder particles, reduce their bonding ability, and avoid the phenomenon of re-agglomeration; at the same time, these lubricants contain hydrocarbon elements, and it is difficult to completely remove the lubricant in the subsequent washing process. The residual lubricant can generate hydrogen (H2) during the calcination process of the ceramic powder. 2 ), carbon monoxide (CO) and other reducing gases can reduce the promotion of diffusion by the surface oxide layer and inhibit the occurrence of hard agglomeration during calcination, making the texture of the obtained ceramic target more uniform and improving the quality of the target.

[0025] Preferably, the lubricant aqueous solution is a glycerol aqueous solution.

[0026] Furthermore, the mass fraction of the lubricant in the lubricant aqueous solution is 5-8%;

[0027] Preferably, the mass fraction of the lubricant in the lubricant aqueous solution is 7%.

[0028] Further, in step S3, the volume mass ratio of the lubricant aqueous solution to the ultrasonic suspension is (2-3):1;

[0029] Preferably, the volume mass ratio of the lubricant aqueous solution to the ultrasonic suspension is 2.5:1.

[0030] Further, in step S4, the drying method is: placing the washed solid separation in a vacuum drying oven at 120° C. for 2-3 hours;

[0031] Preferably, the drying method is: placing the washed solid separator in a vacuum drying oven at 120° C. and drying for 2.5 hours.

[0032] In a second aspect, the present invention also discloses an application of a dispersion method of granulated microspheres obtained by the spray drying method as described above, characterized in that it is used for the preparation of ceramic powders, including indium tin oxide (ITO) powder, aluminum oxide (AL 2 O 3 ) powder, zirconium oxide (Zr(OH) 4 ) powder, silicon carbide (SiC) powder, silicon nitride (Si3N 4 ) powder, etc.

[0033] Beneficial effects of the present invention:

[0034] 1. In the method for dispersing granulated microspheres obtained by the spray drying method of the present invention, through the method of freeze-drying, the ultrasonic suspension is frozen into a block. During this process, the water inside the granulated microspheres that have not been dispersed will freeze and expand, and the generated stress will intensify the separation of powder particles, thereby reducing the binding force between powder particles; after thawing, the ice between the powder particles in the granulated microspheres will turn into water and dissolve in the lubricant aqueous solution, and at the same time, the powder particles will automatically separate, achieving the purpose of dispersion, without damaging the surface structure of the powder particles, and the powder particles can be more fully dispersed.

[0035] 2. In the method for dispersing granulated microspheres obtained by the spray drying method of the present invention, when thawing the frozen ultrasonic suspension, a lubricant aqueous solution is used. The use of the lubricant aqueous solution can form a lubricating film layer on the surface of the dispersed powder particles, reduce their binding ability, and avoid the phenomenon of re-agglomeration.

[0036] 3. In the method for dispersing granulated microspheres obtained by the spray drying method of the present invention, when thawing the frozen ultrasonic suspension, a lubricant aqueous solution is used. These lubricants contain carbon and hydrogen elements. During the subsequent washing process, it is difficult to completely remove the lubricants. The residual lubricants can generate reducing gases such as H 2 , CO, etc. during the calcination process of the ceramic powder, reduce the promotion of surface oxidation layer on diffusion, inhibit the occurrence of hard agglomeration phenomenon during the calcination process, and are more evenly heated during the calcination treatment, the original crystal morphology is more regular, round, the size is more uniform, the hard agglomeration between particles is effectively reduced, and the powder performance is improved. Brief Description of the Drawings

[0037] The present invention will be further described below in conjunction with the drawings.

[0038] Figure 1 It is the SEM image of the zirconium hydroxide powder material obtained by dispersion in Example 1 of the present invention;

[0039] Figure 2 It is the SEM image of the zirconium hydroxide powder material obtained by dispersion in Example 2 of the present invention;

[0040] Figure 3 It is the SEM image of the zirconium hydroxide powder material obtained by dispersion in Comparative Example 3 of the present invention;

[0041] Figure 4 It is the SEM image of the zirconium hydroxide powder material obtained by dispersion in Comparative Example 4 of the present invention;

[0042] Figure 5 It is the SEM image of the zirconium hydroxide powder material obtained by dispersion in Example 1 of the present invention after calcination;

[0043] Figure 6This is a SEM picture of the zirconium hydroxide powder material obtained by dispersion in Example 2 of the present invention after calcination;

[0044] Figure 7 This is a SEM picture of the zirconium hydroxide powder material obtained by dispersion in Comparative Example 3 of the present invention after calcination;

[0045] Figure 8 This is a SEM picture of the zirconium hydroxide powder material obtained by dispersion in Comparative Example 4 of the present invention after calcination. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] The zirconium hydroxide granulated microspheres (D10=10.502um; D50=24.496um; D90=41.878um; D100=66.006um), indium tin oxide granulated microspheres (D10=11.205um; D50=25.102um; D90=42.562um; D100=65.256um) and silicon carbide granulated microspheres (D10=10.352um; D50=24.104um; D90=40.126um; D100=63.589um) obtained by the spray drying method used in the following examples and comparative examples were all provided by Pioneer Thin Film Materials (Anhui) Co., Ltd.; the polyethylene glycol aqueous solution, the sodium polyacrylate aqueous solution, the glycerol aqueous solution and the silicone aqueous solution were all self-prepared, wherein the sources of each raw material are as follows:

[0048] Polyethylene glycol: Jiangsu Haian Petrochemical Plant;

[0049] Polyacrylic acid: Jiangsu Caiwei Biotechnology Co., Ltd.;

[0050] Glycerol: Hubei Xinghengye Technology Co., Ltd.;

[0051] Silicone: Dongguan Xinwei Plastic Raw Materials Co., Ltd.

[0052] Example 1

[0053] The zirconium hydroxide granulated microspheres obtained by spray drying are dispersed, comprising the following steps:

[0054] Step 1, placing 300 g of zirconium hydroxide granulated microspheres in 900 mL of a 3% by mass polyethylene glycol aqueous solution, and letting it stand for 25 minutes to obtain a suspension;

[0055] Step 2, transferring the suspension to an ultrasonic processor and ultrasonically treating it at 30 kHz for 15 min to obtain an ultrasonic suspension;

[0056] Step 3, transferring the ultrasonic suspension to a freezer, freezing it to below -20°C within 2 hours and keeping it for 22 hours, then taking it out and placing it in 2250 mL, 45°C, 6% glycerol aqueous solution to thaw for 2.5 hours, then filtering to separate the filtrate and the filter material, transferring the filter material to a freezer again, freezing it to below -20°C within 2 hours and keeping it for 22 hours, then taking it out and placing it in the filtrate at 45°C to thaw for 2.5 hours to obtain a thawed suspension;

[0057] Step 4: transfer the thawed suspension into a centrifuge for centrifugal separation, collect the solid separation, wash the solid separation twice with deionized water, and finally place it in a vacuum drying oven at 120° C. for 2.5 hours to obtain zirconium hydroxide powder material.

[0058] Example 2

[0059] The zirconium hydroxide granulated microspheres obtained by spray drying are dispersed, comprising the following steps:

[0060] Step 1, placing 300 g of zirconium hydroxide granulated microspheres in 600 mL of a 5% by mass polyethylene glycol aqueous solution, and letting it stand for 30 minutes to obtain a suspension;

[0061] Step 2, transferring the suspension to an ultrasonic processor and ultrasonically treating it at 20 kHz for 20 min to obtain an ultrasonic suspension;

[0062] Step 3, transferring the ultrasonic suspension to a freezer, freezing it to below -20°C within 2 hours and keeping it for 20 hours, then taking it out and placing it in 1800 mL, 40°C, 8% by mass glycerol aqueous solution to thaw for 2 hours, then filtering to separate the filtrate and the filter material, transferring the filter material to a freezer again, freezing it to below -20°C within 2 hours and keeping it for 20 hours, then taking it out and placing it in the filtrate at 40°C to thaw for 2.5 hours to obtain a thawed suspension;

[0063] Step 4: transfer the thawed suspension into a centrifuge for centrifugal separation, collect the solid separation, wash the solid separation twice with deionized water, and finally place it in a vacuum drying oven at 120° C. for 2 hours to obtain zirconium hydroxide powder material.

[0064] Example 3

[0065] The zirconium hydroxide granulated microspheres obtained by spray drying are dispersed, comprising the following steps:

[0066] Step 1: Place 300 g of zirconium hydroxide granulated microspheres in 1500 mL of a 2% sodium polyacrylate aqueous solution and allow to stand for 20 minutes to obtain a suspension;

[0067] Step 2, transferring the suspension to an ultrasonic processor and ultrasonically treating it at 40 kHz for 10 min to obtain an ultrasonic suspension;

[0068] Step 3, transferring the ultrasonic suspension to a freezer, freezing it to below -20°C within 2 hours and keeping it for 24 hours, then taking it out and placing it in 4500mL, 50°C, 5% by mass silicone aqueous solution for thawing for 3 hours, then filtering to separate the filtrate and the filter material, transferring the filter material to a freezer again, freezing it to below -20°C within 2 hours and keeping it for 24 hours, then taking it out and placing it in 40°C filtrate for thawing for 3 hours to obtain a thawed suspension;

[0069] Step 4: transfer the thawed suspension into a centrifuge for centrifugal separation, collect the solid separation, wash the solid separation with deionized water for 3 times, and finally place it in a vacuum drying oven at 120° C. for 3 hours to obtain zirconium hydroxide powder material.

[0070] Example 4

[0071] Compared with Example 1, the only difference is that the zirconium hydroxide granulated microspheres obtained by spray drying are replaced by indium tin oxide granulated microspheres obtained by spray drying, and the other conditions and steps are exactly the same, and finally an indium tin oxide powder material is obtained.

[0072] Example 5

[0073] Compared with Example 1, the only difference is that the zirconium hydroxide granulated microspheres obtained by spray drying are replaced by silicon carbide granulated microspheres obtained by spray drying, and the other conditions and steps are exactly the same, and finally a silicon carbide powder material is obtained.

[0074] Comparative Example 1

[0075] The zirconium hydroxide granulated microspheres obtained by spray drying are dispersed, comprising the following steps:

[0076] Step 1, placing 300 g of zirconium hydroxide granulated microspheres in 900 mL of a 3% by mass polyethylene glycol aqueous solution, and letting it stand for 25 minutes to obtain a suspension;

[0077] Step 2: Transfer the suspension to a freezer, freeze it to below -20°C within 2 hours, keep it for 22 hours, then take it out and place it in 2250 mL, 45°C, 6% glycerol aqueous solution to thaw for 2.5 hours, then filter it to separate the filtrate and the filter material, transfer the filter material to a freezer again, freeze it to below -20°C within 2 hours, keep it for 22 hours, then take it out and place it in 45°C filtrate to thaw for 2.5 hours to obtain a thawed suspension;

[0078] Step 3: transfer the thawed suspension into a centrifuge for centrifugal separation, collect the solid separation, wash the solid separation twice with deionized water, and finally place it in a vacuum drying oven at 120° C. for 2.5 hours to obtain zirconium hydroxide powder material.

[0079] Comparative Example 2

[0080] The zirconium hydroxide granulated microspheres obtained by spray drying are dispersed, comprising the following steps:

[0081] Step 1, placing 300 g of zirconium hydroxide granulated microspheres in 900 mL of a 3% by mass polyethylene glycol aqueous solution, and letting it stand for 25 minutes to obtain a suspension;

[0082] Step 2, transferring the suspension to an ultrasonic processor and ultrasonically treating it at 30 kHz for 15 min to obtain an ultrasonic suspension;

[0083] Step 3: Transfer the ultrasonic suspension to a freezer, freeze it to below -20°C within 2 hours, keep it for 22 hours, then take it out and place it in a 2250 mL, 45°C aqueous solution to thaw for 2.5 hours, then filter it to separate the filtrate and the filter material, transfer the filter material to a freezer again, freeze it to below -20°C within 2 hours, keep it for 22 hours, then take it out and place it in a filtrate at 45°C to thaw for 2.5 hours to obtain a thawed suspension;

[0084] Step 4: transfer the thawed suspension into a centrifuge for centrifugal separation, collect the solid separation, wash the solid separation twice with deionized water, and finally place it in a vacuum drying oven at 120° C. for 2.5 hours to obtain zirconium hydroxide powder material.

[0085] Comparative Example 3

[0086] The zirconium hydroxide granulated microspheres obtained by spray drying are dispersed, comprising the following steps:

[0087] Step 1, placing 300 g of zirconium hydroxide granulated microspheres in 900 mL of a 3% by mass polyethylene glycol aqueous solution, and letting it stand for 25 minutes to obtain a suspension;

[0088] Step 2, transferring the suspension to an ultrasonic processor and ultrasonically treating it at 30 kHz for 15 min to obtain an ultrasonic suspension;

[0089] Step 3: transfer the ultrasonic suspension into a centrifuge for centrifugal separation, collect the solid separation, wash the solid separation twice with deionized water, and finally place it in a vacuum drying oven at 120° C. for 2.5 hours to obtain a zirconium hydroxide powder material.

[0090] Comparative Example 4

[0091] The zirconium hydroxide granulated microspheres obtained by the spray drying method are dispersed using the existing mechanical stirring technology, comprising the following steps:

[0092] 300 g of zirconium hydroxide granulated microspheres were placed in a crusher (model: YHEP-100×60) for stirring and crushing to obtain zirconium hydroxide powder material.

[0093] The powder materials obtained in Examples 1-5 and Comparative Examples 1-4 were sampled and sent to PSD for inspection under the same conditions. Among them, the SEM images of the powder materials obtained in Examples 1-2 are shown as follows: Figure 1-2 As shown, the SEM images of the powder materials obtained in Comparative Examples 3-4 are as follows Figure 3-4 As shown, the particle sizes of the granulated microspheres and powder materials before and after dispersion are listed in Table 1. Table 1 is as follows:

[0094] Table 1

[0095]

[0096]

[0097] By analyzing the data in Table 1, it can be seen that compared with Comparative Examples 1-4, the particle size of the powder material obtained by dispersion in Examples 1-5 varies more than the particle size of the granulated microspheres before dispersion, and the refinement effect is stronger, indicating that the method of the present invention can achieve a better dispersion effect on the granulated microspheres.

[0098] Next, the sampled powder materials obtained in Examples 1-5 and Comparative Examples 1-4 are calcined to form a target material. The calcination method is as follows:

[0099] Muffle furnace calcination curve: 300min from 25℃ to 1000℃, keep at 1000℃ for 180min, then cool from 1000℃ to room temperature for 300min.

[0100] Then, the calcined target was subjected to PSD inspection under the same conditions. The SEM images of the calcined target obtained in Examples 1-2 are shown in FIG. Figure 5-6 As shown, the SEM images of the calcined targets obtained in Comparative Examples 3-4 are as follows Figure 7-8 As shown, the particle sizes of the granulated microspheres and powder materials before and after dispersion are listed in Table 2. Table 2 is as follows:

[0101] Table 2

[0102]

[0103]

[0104] By analyzing the data in Table 2, it can be seen that compared with Comparative Examples 1-4, the powder materials dispersed in Examples 1-5 have more fine and uniform internal particle sizes after calcination. Figure 5-8 It can be seen that compared with comparative examples 3-4, after high-temperature calcination, the powder materials of Examples 1-2 have rounded original crystal particles, uniform size, and significantly improved agglomeration.

[0105] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for dispersing granulated microspheres obtained by spray drying, characterized in that: The steps include: S1. Place the granulated microspheres in a dispersant aqueous solution and let stand for 20-30 minutes to obtain a suspension; S2, transferring the suspension to an ultrasonic processor for ultrasonic treatment to obtain an ultrasonic suspension; S3, transferring the ultrasonic suspension to a freezer, freezing it to below -20°C within 2 hours, keeping it for 20-24 hours, then taking it out and placing it in a lubricant aqueous solution at 40-50°C for thawing for 2-3 hours, then filtering it to separate the filtrate from the filter material, transferring the filter material to a freezer again, freezing it to below -20°C within 2 hours, keeping it for 20-24 hours, then taking it out and placing it in a filtrate at 40-50°C for thawing for 2-3 hours, and obtaining a thawed suspension; S4. Filter or centrifuge the thawed suspension to collect the solid separation, wash the solid separation with deionized water for 2-3 times, and finally dry to obtain a powder material.

2. The method for dispersing granulated microspheres obtained by the spray drying method according to claim 1, characterized in that: In step S1, the dispersant aqueous solution is a polyethylene glycol aqueous solution or a sodium polyacrylate aqueous solution.

3. The method for dispersing granulated microspheres obtained by the spray drying method according to claim 2, characterized in that: The mass fraction of the dispersant in the dispersant aqueous solution is 2% to 5%.

4. The method for dispersing granulated microspheres obtained by the spray drying method according to claim 1, characterized in that: In step S1, the dosage ratio of the granulated microspheres to the dispersant aqueous solution is 1 g: (2-5) mL.

5. The method for dispersing granulated microspheres obtained by the spray drying method according to claim 1, characterized in that: In step S2, the method of performing ultrasonic treatment is: ultrasonic treatment at 20-40 kHz for 10-20 min.

6. The method for dispersing granulated microspheres obtained by spray drying according to claim 1, characterized in that: In step S3, the lubricant aqueous solution is any one of a polyol aqueous solution, a glycerol aqueous solution, and a silicone aqueous solution.

7. The method for dispersing granulated microspheres obtained by spray drying according to claim 6, characterized in that: The mass fraction of the lubricant in the lubricant aqueous solution is 5% to 8%.

8. The method for dispersing granulated microspheres obtained by spray drying according to claim 1, characterized in that: In step S3, the volume mass ratio of the lubricant aqueous solution to the ultrasonic suspension is (2-3):

1.

9. The method for dispersing granulated microspheres obtained by spray drying according to claim 1, characterized in that: In step S4, the drying method is: placing the washed solid separation in a vacuum drying oven at 120° C. for 2-3 hours.

10. The use of the method for dispersing granulated microspheres obtained by the spray drying method according to any one of claims 1 to 9, characterized in that: Used for the preparation of ceramic powders.

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