A method for preparing silicon powder slurry

Abstract

The present invention relates to the field of silicon material technology, and specifically to a method for preparing silicon powder slurry. According to the present invention, dry silicon powder, an additive and a solvent 1 are added to a sand mill for sand grinding and dispersion to obtain a slurry; then the slurry is added to a double planetary mixer for dispersion and stirring to obtain a stirred slurry. The colloid can be pre-dissolved before stirring, saving time. After the slurry is dispersed and stirred, an ultrasonic disperser is placed in the double planetary mixer, and after ultrasonic dispersion, the pre-dissolved colloid and Class II plasticizer are added for stirring; after the stirring is completed, vacuum degassing is directly turned on without slurry transfer. Using a double planetary mixer to prepare silicon powder slurry can shorten the preparation time to 7 hours, significantly improve efficiency, and there is no need to transfer the slurry to other equipment, avoiding problems such as loss and crusting, and ensuring the quality of the slurry.

Description

Technical Field

[0001] The invention relates to the technical field of silicon materials, and in particular to a method for preparing silicon powder slurry. Background Art

[0002] In the existing silicon powder slurry preparation technology, a ball mill is usually used to prepare the slurry, and then a deaerator is used to thicken and defoam the silicon powder slurry. However, the dispersion efficiency of the ball mill is low, and the production capacity cannot meet the growing demand; at the same time, during the transfer of the slurry to the deaerator, a large loss will occur, which is prone to problems such as soft agglomeration, crusting, and the introduction of impurities, thus affecting the quality of the slurry.

[0003] Therefore, it is necessary to provide a method for efficiently preparing silicon powder slurry. The present invention considers using a double planetary mixer, a deaerator, a sand mill and other equipment to prepare a silicon powder slurry. Among them, the double planetary mixer is a new type of stirring equipment that can efficiently stir, dissolve, disperse and homogenize various mixed liquids and powders, and is suitable for materials with different viscosities and solid contents. The equipment is equipped with high-speed, low-speed and movable scraper components. The low-speed stirring component adopts planetary gear transmission, so that the stirring paddle also rotates during the revolution, so that the material moves up and down and around to achieve the ideal mixing effect in a shorter time. The high-speed dispersing / emulsifying component revolves with the planetary box and rotates at high speed at the same time, thereby bringing strong shearing and dispersing mixing effects to the material. The deaerator is a device that can create a certain vacuum environment to achieve material thickening and defoaming. The equipment consists of a vacuum pump, a stirring paddle, and a tank body. Under certain vacuum conditions, the equipment can extract the solvent and tiny bubbles in the material to achieve the target viscosity and solid content. The sand mill is a continuously operated fully enclosed grinding and dispersing equipment. Its working principle is to transport the liquid raw material into the enclosed grinding cylinder of the sand mill through a pump, and then the main engine drives the medium grinding beads to rotate at high speed, so that the raw material is pressurized and high-speed rotated in the narrow gap between the grinding beads to produce grinding functions such as mixing, emulsification, dispersion, kneading and rolling. In this way, the material particles can be quickly ground and refined and the aggregates can be dispersed. The ground material is then output from the grinding cylinder through the high-speed rotating hard tungsten steel separation gap to achieve the required fineness and narrow particle size distribution range of the raw material.

[0004] In order to overcome the defects of the prior art, the present invention provides a method for preparing silicon powder slurry. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing silicon powder slurry to solve the problems in the prior art.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] A method for preparing silicon powder slurry comprises the following steps:

[0008] Step 1: Add silicon powder, additive and solvent 1 to a sand mill in sequence for sand grinding and dispersion to obtain a slurry; mix and stir the binder, solvent 2 and type I plasticizer to pre-dissolve the colloid to obtain a colloid;

[0009] Step 2: Add the slurry obtained in step 1 to a planetary mixer for stirring to obtain a stirred slurry; then place an ultrasonic disperser into the planetary mixer in step 2, and ultrasonically disperse for 10 to 15 minutes, with an ultrasonic power of 2-3KW and a frequency of 20-22KHz;

[0010] Step 3: Add the colloid and Class II plasticizer obtained in step 1 to the stirring slurry and stir. After the stirring is completed, close the dispersion disk and continue stirring for 1 to 1.5 hours. After the stirring is completed, directly start the vacuum degassing to degas to the required solid content to obtain the finished product.

[0011] More optimally, in step 1, the water content of the silicon powder is 0.1-0.5%, and the solvent 1 is ethanol.

[0012] More optimally, in step one, the additive includes a dispersant and a sintering aid; the dispersant is any one or more of AAB-0851 of NOF Corporation, AFB-1521 of NOF Corporation, AKM-0531 of NOF Corporation, and XYS-5160 of Yunfeng Corporation, specifically any one or more of castor oil, triolein, polyacrylamide, fluorine oil, refined fish oil, oleic acid, stearic acid, linoleic acid, polyisobutylene, and polyethylene glycol; the sintering aid is any one or more of alumina powder, magnesium oxide powder, and rare earth element oxides, and the water content is less than 0.5%.

[0013] More optimally, the rare earth element oxide is any one or more of oxide powders of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, yttrium, and scandium.

[0014] More optimally, in step 1, the sanding power is 1.1-1.3 KW, and the sanding time is 10-15 min.

[0015] More optimally, in step one, the binder is any one or more of vinyl, cellulose, and acrylic resin; the solvent 2 is any one or more of ethanol, ethyl acetate, and cyclohexanone; the Class I plasticizer is a mixture of any two of DBP, DOP, BBP, triethylene glycol diisobutyrate, polyethylene, polypropylene, triethylene, dibenzoate, and butyl stearate.

[0016] More optimally, in step one, when the colloid is pre-dissolved, the stirring time is 8 to 10 hours, the heating temperature is 70 to 75° C., and the stirring rate is 800 to 850 r / min.

[0017] More optimally, in step 2, the speed of the dispersing disk of the planetary mixer is 2490-2510 rpm, the speed of the stirring disk of the planetary mixer is 60-80 rpm; the stirring temperature is 40-60° C., and the stirring time is 1-1.5 h.

[0018] More optimally, in step three, the speed of the dispersing disk of the planetary mixer is 2490-2510 rpm, the speed of the stirring disk of the planetary mixer is 60-80 rpm; the stirring temperature is 40-50° C., and the stirring time is 4-5 h.

[0019] More optimally, in step three, the vacuum degree of the vacuum degassing is -0.15 to -0.09 MPa; the solid content is 68 to 72%, and the degassing time is 1 to 8 hours.

[0020] More optimally, in step three, the Class II plasticizer is polyethylene glycol.

[0021] Beneficial effects of the present invention:

[0022] In order to solve the above technical problems, the present invention provides a method for preparing silicon powder slurry by sand milling and double planetary stirring. The present invention adds dry silicon powder, additives and solvent 1 to a sand mill for sand milling and dispersion to obtain a slurry; then the slurry is added to a double planetary mixer for dispersion and stirring to obtain a stirred slurry. The colloid can be pre-dissolved before stirring, saving time. After the slurry is dispersed and stirred, the ultrasonic disperser is placed in the double planetary mixer, and after ultrasonic dispersion, the pre-dissolved colloid and Class II plasticizer are added for stirring; after stirring, the vacuum degassing is directly turned on without slurry transfer. In this way, the use of a double planetary mixer to prepare silicon powder slurry can shorten the preparation time to 7 hours, significantly improving efficiency; the slurry does not need to be transferred between various equipment, there is no loss, and various uncertain factors such as slurry crusting during the transfer process can be eliminated to ensure the quality of the slurry.

[0023] The present invention is characterized in that:

[0024] 1. The present invention provides a method for rapid slurry preparation and degassing of silicon powder slurry;

[0025] 2. The method for preparing silicon powder slurry of the present invention is simple and easy to implement, and significantly improves the preparation efficiency;

[0026] 3. The present invention can effectively improve the problems of loss, crusting and easy introduction of impurities caused by the transfer of silicon powder slurry between equipment in the prior art, and ensure the production capacity and quality of the slurry;

[0027] 4. The present invention innovatively uses sand milling, double planetary stirring and ultrasound to prepare silicon powder slurry. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0029] Figure 1-1 This is a graph showing the particle size test results of the slurry after ultrasonic dispersion in step 2 of Example 1 of the present invention;

[0030] Figure 1-2 This is a graph showing the particle size test results of the slurry in Comparative Example 1 of the present invention after ultrasonic dispersion in step 2;

[0031] Figure 1-3 This is a graph showing the particle size test results of the slurry after stirring and dispersing in step 2 of comparative example 2 of the present invention;

[0032] Figure 1-4 This is a graph showing the particle size test results of the slurry after ball milling dispersion in step 1 of Comparative Example 3 of the present invention;

[0033] Figure 2-1 This is a graph showing the Zeta potential test result of the slurry after ultrasonic dispersion in step 2 of Example 1 of the present invention;

[0034] Figure 2-2 This is a graph showing the Zeta potential test result of the slurry of Comparative Example 1 of the present invention after ultrasonic dispersion in step 2;

[0035] Figure 2-3 This is a graph showing the Zeta potential test result of the slurry of Comparative Example 2 of the present invention after stirring and dispersing in step 2;

[0036] Figure 2-4 This is a graph showing the Zeta potential test results of the slurry of Comparative Example 3 of the present invention after ball milling dispersion in step 1;

[0037] Figure 3-1 The silicon powder green body is obtained by tape casting the silicon powder slurry product prepared in Example 1 of the present invention, and the electron microscope image of the silicon powder green body in Example 1;

[0038] Figure 3-2 The silicon powder green body is obtained by tape casting the silicon powder slurry product prepared in Comparative Example 1 of the present invention, and the electron microscope image of the silicon powder green body of Comparative Example 1;

[0039] Figure 3-3 The silicon powder green body is obtained by tape casting the silicon powder slurry product prepared in Comparative Example 2 of the present invention, and the electron microscope image of the silicon powder green body of Comparative Example 2;

[0040] Figure 3-4The silicon powder green body is obtained by tape casting the silicon powder slurry product prepared in Comparative Example 3 of the present invention. This is an electron microscope image of the silicon powder green body of Comparative Example 3. DETAILED DESCRIPTION

[0041] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in 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.

[0042] Source of raw materials:

[0043] Polyvinyl butyral, provided by Kuraray Co., Ltd. of Japan, with a molecular weight of 20,000-80,000; polyethylene glycol, provided by Green Union (Jining) Chemical Technology Co., Ltd., with a molecular weight of 400; silicon powder, with a particle size of 30 μm; castor oil, provided by Nanjing Qiduning Chemical Co., Ltd., with an active ingredient content of 99%.

[0044] Example 1: Step 1: 452.5 g of silicon powder with a water content of 0.4%, 10 g of castor oil, 40.5 g of yttrium oxide, 7 g of magnesium oxide and 300 g of ethanol are sequentially added to a sand mill for sand grinding and dispersion, the sand grinding power is 1.3 KW, and the sand grinding time is 15 min to obtain a slurry; 78 g of polyvinyl butyral, 78 g of ethanol, 78 g of ethyl acetate, 11.7 g of DBP and 11.7 g of DOP are mixed and stirred to pre-dissolve the colloid, the stirring time is 8 h, the heating temperature is 70 ° C, and the stirring rate is 800 r / min to obtain a colloid;

[0045] Step 2: Add the slurry obtained in step 1 to a planetary mixer for stirring, the speed of the dispersion disk of the planetary mixer is 2490 rpm, and the speed of the stirring disk of the planetary mixer is 60 rpm; the stirring temperature is 40° C., the stirring time is 1 hour, and a stirring slurry is obtained; then the ultrasonic disperser is placed in the planetary mixer in step 2, and ultrasonic dispersion is performed for 10 minutes, the ultrasonic power is 2 KW, and the frequency is 20 KHz;

[0046] Step three: Add 198g of colloid and 18g of polyethylene glycol obtained in step one to the stirring slurry and stir. The speed of the disperser disk of the planetary mixer is 2490rpm, and the speed of the stirring disk of the planetary mixer is 60rpm; the stirring temperature is 40°C, and the stirring time is 4h; after the stirring is completed, the disperser disk is closed and the stirring is continued for 1h; after the stirring is completed, the vacuum degassing is directly turned on, the vacuum degree of the vacuum degassing is -0.15MPa, and the degassing time is 1h to obtain the finished product, wherein the silicon powder slurry preparation time is a total of 7h25min.

[0047] Comparative Example 1: The sand mill in step 1 is replaced by a ball mill, and the rest is the same as Example 1, and the specific steps are as follows: Step 1: 452.5g of silicon powder with a water content of 0.4%, 10g of castor oil, 40.5g of yttrium oxide, 7g of magnesium oxide and 300g of ethanol are added to a ball mill in sequence for ball milling dispersion, the ball milling power is 20%, and the ball milling time is 15min to obtain a slurry; 78g of polyvinyl butyral, 78g of ethanol, 78g of ethyl acetate, 11.7g of DBP and 11.7g of DOP are mixed and stirred to pre-dissolve the colloid, the stirring time is 8h, the heating temperature is 70°C, and the stirring rate is 800r / min to obtain a colloid;

[0048] Step 2: Add the slurry obtained in step 1 to a planetary mixer for stirring, the speed of the dispersion disk of the planetary mixer is 2490 rpm, and the speed of the stirring disk of the planetary mixer is 60 rpm; the stirring temperature is 40° C., the stirring time is 1 hour, and a stirring slurry is obtained; then the ultrasonic disperser is placed in the planetary mixer in step 2, and ultrasonic dispersion is performed for 10 minutes, the ultrasonic power is 2 KW, and the frequency is 20 KHz;

[0049] Step three: Add 198g of colloid and 18g of polyethylene glycol obtained in step one to the stirring slurry and stir. The speed of the disperser disk of the planetary mixer is 2490rpm, and the speed of the stirring disk of the planetary mixer is 60rpm; the stirring temperature is 40°C, and the stirring time is 4h; after the stirring is completed, the disperser disk is closed and the stirring is continued for 1h; after the stirring is completed, the vacuum degassing is directly turned on, the vacuum degree of the vacuum degassing is -0.15MPa, and the degassing time is 1h to obtain the finished product, wherein the silicon powder slurry preparation time is a total of 7h25min.

[0050] Comparative Example 2: The ultrasonic dispersion step in step 3 is removed, and the rest is the same as Example 1, and the specific steps are as follows: Step 1: 452.5g of silicon powder with a water content of 0.4%, 10g of castor oil, 40.5g of yttrium oxide, 7g of magnesium oxide and 300g of ethanol are added to a sand mill in sequence for sand milling dispersion, the sand milling power is 1.3KW, and the sand milling time is 15min to obtain a slurry; 78g of polyvinyl butyral, 78g of ethanol, 78g of ethyl acetate, 11.7g of DBP and 11.7g of DOP are mixed and stirred to pre-dissolve the colloid, the stirring time is 8h, the heating temperature is 70°C, and the stirring rate is 800r / min to obtain a colloid;

[0051] Step 2: Add the slurry obtained in step 1 to a planetary mixer for stirring, the speed of the dispersion disk of the planetary mixer is 2490 rpm, the speed of the stirring disk of the planetary mixer is 60 rpm; the stirring temperature is 40° C., the stirring time is 1 h, and a stirring slurry is obtained;

[0052] Step three: add 198g of colloid and 18g of polyethylene glycol obtained in step one to the stirring slurry and stir. The speed of the disperser disk of the planetary mixer is 2490rpm, and the speed of the stirring disk of the planetary mixer is 60rpm; the stirring temperature is 40°C, and the stirring time is 4h; after the stirring is completed, the disperser disk is closed and the stirring is continued for 1h; after the stirring is completed, the vacuum degassing is directly turned on, the vacuum degree of the vacuum degassing is -0.15MPa, and the degassing time is 1h to obtain the finished product, wherein the silicon powder slurry preparation time is a total of 7h15min.

[0053] Comparative Example 3: The sand milling process in step 1 is replaced by a ball milling process, step 2 is removed, and the planetary stirring in step 3 is removed. The rest is the same as Example 1, and the specific steps are as follows: Step 1: 452.5g of silicon powder with a water content of 0.4%, 10g of castor oil, 40.5g of yttrium oxide, 7g of magnesium oxide, 300g of ethanol, 60g of polyvinyl butyral, 60g of ethanol, 60g of ethyl acetate, 9g of DBP, 9g of DOP, and 18g of polyethylene glycol are added to a ball mill in sequence, and ball milled for 24h to obtain a ball-milled slurry;

[0054] Step 2: vacuum degassing the ball mill slurry, the vacuum degree of vacuum degassing is -0.15MPa, and the degassing time is 1h.

[0055] Detection test:

[0056] Sedimentation test: The silicon powder slurry prepared by the present invention was used as a sample to carry out a sedimentation test. The test results are shown in Table 1 below.

[0057] Viscosity test: A digital rotational viscometer was used to test the viscosity of the slurry of Example 1 after stirring in step 3, the viscosity of the slurry of Comparative Example 1 after stirring in step 3, the viscosity of the slurry of Comparative Example 2 after stirring in step 3, and the viscosity of the slurry of Comparative Example 3 after sand grinding and dispersion in step 1; the test results are shown in Table 2.

[0058] Table 1: Settlement test data

[0059]

[0060] Table 2: Viscosity test data

[0061]

[0062] Conclusion: From the analysis of Table 1, it can be seen that the silicon powder slurry prepared by the present invention shows a smaller sedimentation amount in the sedimentation experiment, which indicates that the silicon powder slurry prepared by the present invention has good dispersion stability and anti-settling performance, is not prone to stratification or precipitation, thereby improving its reliability and durability.

[0063] From the analysis of Table 2, it can be seen that the silicon powder slurry preparation method of the present invention can obtain silicon powder slurry with lower viscosity, better uniformity and casting performance.

[0064] from Figure 1-1 to Figure 1-4 The analysis of the particle size test results shows that the method for preparing the silicon powder slurry of the present invention can obtain a narrower particle size distribution and an excellent dispersion effect.

[0065] from Figure 2-1 to Figure 2-4 The Zeta potential test results show that the method for preparing silicon powder slurry according to the present invention can obtain a Zeta potential with a larger absolute value, and the dispersed slurry is more stable.

[0066] from Figure 3-1 to Figure 3-4 The comparison results of electron microscope photos of the green body after slurry casting show that the silicon powder green body prepared by the silicon powder slurry preparation method of the present invention is more uniform.

[0067] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process method article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process method article or device.

[0068] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing silicon powder slurry, characterized in that: The following steps are involved: Step 1: Add silicon powder, additive and solvent 1 to a sand mill in sequence for sand grinding and dispersion to obtain a slurry; mix and stir a binder, solvent 2 and a Class I plasticizer to pre-dissolve a colloid to obtain a colloid; the additive includes a dispersant and a sintering aid; the dispersant is any one or more of castor oil, triolein, polyacrylamide, fluorine oil, refined fish oil, oleic acid, stearic acid, linoleic acid, polyisobutylene, and polyethylene glycol; the sintering aid is any one or more of alumina powder, magnesium oxide powder, and rare earth element oxides; the Class I plasticizer is a mixture of any two of DBP, DOP, BBP, polyethylene, polypropylene, dibenzoate, and butyl stearate; Step 2: Add the slurry obtained in step 1 to a planetary mixer for stirring to obtain a stirred slurry; then place an ultrasonic disperser into the planetary mixer in step 2, and ultrasonically disperse for 10-15 minutes, with an ultrasonic power of 2-3KW and a frequency of 20-22KHz; Step 3: Add the colloid and Class II plasticizer obtained in step 1 to the stirring slurry and stir. After the stirring is completed, close the dispersion disk and continue stirring for 1 to 1.5 hours. After the stirring is completed, directly start vacuum degassing to degas to the required solid content to obtain the finished product; The Class II plasticizer is polyethylene glycol.

2. The method for preparing silicon powder slurry according to claim 1, characterized in that: In step 1, the water content of the silicon powder is 0.1-0.5%, and the solvent 1 is ethanol.

3. The method for preparing silicon powder slurry according to claim 1, characterized in that: In step 1, the rare earth element oxide is any one or more of the oxide powders of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, yttrium, and scandium; and the water content of the sintering aid is less than 0.5%.

4. The method for preparing silicon powder slurry according to claim 1, characterized in that: In step 1, the sanding power is 1.1~1.3KW, and the sanding time is 10~15min.

5. The method for preparing silicon powder slurry according to claim 1, characterized in that: In step 1, the binder is any one or more of vinyl, cellulose, and acrylic resin; the solvent 2 is any one or more of ethanol, ethyl acetate, and cyclohexanone.

6. The method for preparing silicon powder slurry according to claim 1, characterized in that: In step 1, when the colloid is pre-dissolved, the stirring time is 8-10 hours, the heating temperature is 70-75°C, and the stirring speed is 800-850 r / min.

7. The method for preparing silicon powder slurry according to claim 1, characterized in that: In step 2, the speed of the dispersing disk of the planetary mixer is 2490-2510 rpm, the speed of the stirring disk of the planetary mixer is 60-80 rpm; the stirring temperature is 40-60° C., and the stirring time is 1-1.5 h.

8. The method for preparing silicon powder slurry according to claim 1, characterized in that: In step three, the speed of the dispersing disk of the planetary mixer is 2490~2510rpm, the speed of the stirring disk of the planetary mixer is 60~80rpm; the stirring temperature is 40~50℃, and the stirring time is 4~5h.

9. The method for preparing silicon powder slurry according to claim 1, characterized in that: In step three, the vacuum degree of the vacuum degassing is -0.15~-0.09MPa; the solid content is 68~72%, and the degassing time is 1~8h.

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