Superfine active silica powder and preparation method thereof

Abstract

The invention belongs to the technical field of inorganic non-metallic material processing, and discloses superfine active silica powder and a preparation method thereof. The preparation method of the superfine active silica powder comprises the following steps: mixing silica powder, a part of a surface modifier and water, and grinding to obtain superfine silica powder slurry; and drying the superfine silica powder slurry, mixing with the residual surface modifier, modifying, and cooling to obtain the superfine active silica powder. The obtained superfine active silica powder is high in whiteness, high in fineness, low in oil absorption, low in moisture content, high in activation degree and low in magnetic impurity content, and can be applied to the high-grade, high-precision and advanced industrial field.

Description

Technical Field

[0001] The present invention relates to the technical field of inorganic non-metallic material processing, in particular to an ultrafine active silicon micropowder and a preparation method thereof. Background Art

[0002] Silica powder, which primarily includes crystalline silica powder, fused silica powder, and soft silica powder, offers excellent insulation, heat resistance, chemical stability, acid and alkali resistance, and corrosion resistance. It is commonly used to improve the performance of products such as powder coatings, rubber, engineering plastics, copper-clad laminates, molding compounds, and precision ceramics. Currently, the processing technology for domestic silica powder products mostly involves ball milling and grading, resulting in a particle size (D50) of approximately 3μm at its finest, which is insufficient to meet the application requirements of high-end applications such as copper-clad laminates, molding compounds, and electronic adhesives.

[0003] To solve the above problems, existing technicians have proposed ultrafine silicon powder. However, due to its small particle size, large specific surface area, and a large number of hydroxyl groups on the surface, the hydrophilic surface of the ultrafine silicon powder has poor affinity with the hydrophobic organic matrix, resulting in weak interfacial interaction between the ultrafine silicon powder and the polymer, resulting in poor compatibility between the silicon powder and the polymer, which can easily lead to a decrease in the mechanical properties of the material. In addition, the hydroxyl groups on the surface of the ultrafine silicon powder are very likely to produce hydrogen bonds, resulting in spontaneous agglomeration. The above problems limit the application of ultrafine silicon powder in high-precision and cutting-edge industrial fields.

[0004] Therefore, it is of great significance to study and obtain an ultrafine active silicon powder with strong compatibility with high molecular polymers and its preparation method. Summary of the Invention

[0005] In view of this, the present invention provides an ultrafine active silicon micropowder and a preparation method thereof, the purpose of which is to solve the problem of poor compatibility between silicon micropowder and polymer in the prior art, which leads to decreased mechanical properties of the material.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for preparing ultrafine active silicon powder, comprising the following steps:

[0008] (1) mixing silicon micropowder, part of the surface modifier and water and grinding the mixture to obtain an ultrafine silicon micropowder slurry;

[0009] (2) After the ultrafine silicon micropowder slurry is dried, it is mixed with the remaining surface modifier, modified, and then cooled to obtain ultrafine active silicon micropowder.

[0010] Preferably, in step (1), the silicon micropowder is prepared by sequentially ball milling, airflow conveying, and classification of the ore-containing raw material;

[0011] The mineral raw material is natural quartz sand, fused quartz sand or alkali-free glass sand, the feeding frequency of the ball mill is 6-10 Hz, the medium of the ball mill is alumina ceramic, and the induced air volume of the air flow conveying is 12200-12800m 3 / h, the classification speed is 1900~2300rpm.

[0012] Preferably, in step (1), the particle size D50 of the silicon micropowder is 8 to 15 μm, and the mass ratio of silicon micropowder to water is 50 to 70:30 to 50.

[0013] Preferably, in step (1), the grinding speed is 220-300 rpm, and the particle size D50 of the solid particles in the ultrafine silicon powder slurry is less than 2.1 μm.

[0014] Preferably, in step (2), the modification temperature is 100-130°C, the modification time is 15-30 minutes, and the cooling temperature is 20-30°C.

[0015] Preferably, the surface modifier is a vinyl silane coupling agent and / or an epoxy silane coupling agent.

[0016] Preferably, the mass ratio of the sum of the mass of part of the surface modifier and the remaining surface modifier to the mass of the silicon powder is 0.6-1.2:100; the mass ratio of part of the surface modifier to the remaining surface modifier is 2:1-2.

[0017] The present invention also provides ultrafine active silicon micropowder prepared by the method for preparing ultrafine active silicon micropowder, wherein the particle size D50 of the ultrafine active silicon micropowder is less than 2.1 μm.

[0018] It can be seen from the above technical solutions that compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention uses color-sorted and magnetically separated natural quartz sand, fused quartz sand, or alkali-free glass sand as raw materials, resulting in high whiteness and low magnetic impurity content. The resulting silicon micropowder can meet the requirements of many high-tech industrial applications. The present invention utilizes a tandem process of ball milling and stirred milling. The ball milling process can easily process the raw sand into a primary material. The stirred mill uses zirconia beads of different particle sizes for mixed grinding. The grading of the beads reduces the gaps between the beads and increases the contact area between the beads and the slurry, achieving higher grinding efficiency and overcoming the limitations of dry grinding to produce ultrafine silicon micropowder with a D50 less than 2.1 μm.

[0020] The present invention adopts a wet-dry method to carry out surface treatment on ultrafine silicon micropowder in view of the agglomeration of ultrafine silicon micropowder, which can effectively improve the dispersibility of ultrafine silicon micropowder, reduce oil absorption, and enhance the compatibility of silicon micropowder with high molecular polymer. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0022] Figure 1 Schematic diagram of the preparation method of the present invention;

[0023] Figure 2 This is the particle size distribution diagram of the ultrafine active silicon powder obtained in Example 1;

[0024] Figure 3 This is the particle size distribution diagram of the ultrafine active silicon powder obtained in Example 2;

[0025] Figure 4 This is the particle size distribution diagram of the ultrafine active silicon powder obtained in Example 3. DETAILED DESCRIPTION

[0026] The present invention provides a method for preparing ultrafine active silicon powder, comprising the following steps:

[0027] (1) mixing silicon micropowder, part of the surface modifier and water and grinding the mixture to obtain an ultrafine silicon micropowder slurry;

[0028] (2) After the ultrafine silicon micropowder slurry is dried, it is mixed with the remaining surface modifier, modified, and then cooled to obtain ultrafine active silicon micropowder.

[0029] In the present invention, in step (1), silicon micropowder is prepared by sequentially ball milling, air flow conveying and classification of ore-containing raw materials;

[0030] The mineral raw material is preferably natural quartz sand, fused quartz sand or alkali-free glass sand. The feeding frequency of the ball mill is preferably 6-10 Hz, more preferably 7-9 Hz, and more preferably 8 Hz. The medium of the ball mill is preferably alumina ceramic. The lining of the ball mill is preferably alumina ceramic to avoid the introduction of magnetic impurities. The induced air volume of the air flow is preferably 12200-12800 m 3 / h, more preferably 12300-12700m 3 / h, more preferably 12400-12500m 3 / h, and the rotation speed of classification is preferably 1900 to 2300 rpm, more preferably 2000 to 2100 rpm, and further preferably 2050 to 2080 rpm.

[0031] In the present invention, the whiteness of the natural quartz sand, fused quartz sand and alkali-free glass sand is preferably >93%, more preferably >94%, and even more preferably >95%, and the content of magnetic impurities is preferably <20 ppm.

[0032] In the present invention, in step (1), the particle size D50 of the silicon micropowder is preferably 8 to 15 μm, more preferably 9 to 14 μm, and more preferably 10 to 12 μm, and the mass ratio of silicon micropowder to water is preferably 50 to 70:30 to 50, more preferably 55 to 65:35 to 45, and more preferably 58 to 62:38 to 42.

[0033] In the present invention, in the step (1), the grinding speed is preferably 220 to 300 rpm, more preferably 230 to 280 rpm, more preferably 240 to 250 rpm, the grinding time is preferably 50 to 70 min, more preferably 55 to 65 min, more preferably 58 to 60 min, and the particle size D50 of the solid particles in the ultrafine silicon powder slurry is preferably <2.1 μm, more preferably <2.0 μm, and more preferably <1.9 μm.

[0034] In the present invention, the mixing in step (1) is performed by first mixing the silicon micropowder with water and then adding part of the surface modifier.

[0035] In the present invention, in the step (1), the grinding is preferably carried out in a stirred mill, the stirred mill lining of which is preferably made of zirconia, and the medium of the stirred mill is preferably zirconia beads to avoid the introduction of magnetic impurities; the mixture of silicon micropowder and water is preferably transported to the stirred mill for grinding by a diaphragm pump, and the feeding speed of the diaphragm pump is preferably 100 to 1800 L / min, more preferably 300 to 1500 L / min, and more preferably 600 to 1200 L / min; the part of the surface modifier is preferably added through the top inlet of the stirred mill.

[0036] In the present invention, in the step (1), the ball-to-material ratio of the stirred mill is preferably 45-60:40-55, more preferably 50-55:45-50, and more preferably 52-53:47-48; the particle size of the zirconia beads is preferably 0.8-1.5 mm, and more preferably the mass ratio of 0.8-1 mm zirconia beads, 1.1-1.2 mm zirconia beads and 1.3-15 mm zirconia beads is 22-32:10-16:8-13, more preferably 24-30:11-15:9-12, and more preferably 26-28:12-14:10-11.

[0037] In the present invention, in step (2), the drying is preferably flash drying, the flash drying temperature is preferably 300-400°C, more preferably 320-380°C, more preferably 340-350°C, and the flash drying time is preferably 1-3 min, more preferably 1.5-2.5 min, more preferably 2 min.

[0038] In the present invention, in step (2), the modification temperature is preferably 100-130°C, more preferably 105-125°C, more preferably 110-120°C, and the modification time is preferably 15-30 min, more preferably 18-26 min, more preferably 20-24 min; the cooling temperature is preferably 20-30°C, more preferably 22-28°C, more preferably 24-26°C.

[0039] In the present invention, in step (2), the modification is preferably carried out in a modifier, and the modifier is preferably a jet modifier, an SLG modifier or a high-stirring modifier. The material of the inner cavity and the rotor of the modifier is preferably alumina or zirconia to avoid the introduction of magnetic impurities.

[0040] In the present invention, the surface modifier is preferably a vinyl silane coupling agent and / or an epoxy silane coupling agent;

[0041] The surface modifier may also be 3-aminopropyltrimethoxysilane;

[0042] The vinyl silane coupling agent is preferably vinyl tris (2-methoxyethoxy) silane;

[0043] The epoxy hydrocarbon-based silane coupling agent is preferably 3-(2,3-epoxypropoxy)propyltriethoxysilane.

[0044] In the present invention, the mass ratio of the sum of the mass of part of the surface modifier and the remaining surface modifier to the mass of the silicon powder is preferably 0.6 to 1.2:100, more preferably 0.7 to 1.1:100, and more preferably 0.8 to 1:100; the mass ratio of part of the surface modifier to the remaining surface modifier is preferably 2:1 to 2, more preferably 2:1.2 to 1.8, and more preferably 2:1.4 to 1.6.

[0045] The present invention also provides ultrafine active silicon micropowder prepared by the method for preparing ultrafine active silicon micropowder. The particle size D50 of the ultrafine active silicon micropowder is preferably <2.1 μm, more preferably <1.9 μm, and more preferably <1.8 μm.

[0046] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0047] In the embodiment of the present invention, regarding the processing of mineral-containing raw materials, the specifications of the ball mill are 2.2m (Φ) × 7.5m (L), the lining and ball medium of the ball mill are made of alumina ceramic with high hardness (Mohs hardness 9), the specifications of the classifying wheel group are 315mm (Φ) × 6, and the classifier cavity and classifying wheel material are made of alumina ceramic with high hardness (Mohs hardness 9); the grinding is carried out in a vertical stirred mill, the specifications of the stirred mill are 1.2m (Φ) × 3.6m (h), and the lining and grinding medium of the vertical stirred mill are both made of zirconia.

[0048] Example 1

[0049] In this embodiment, the surface modifier is vinyl tris (2-methoxyethoxy) silane, and the mass ratio of the surface modifier to the silicon powder is 0.6:100;

[0050] Natural quartz sand (whiteness 94%, magnetic impurity content 18ppm) was added to a continuously running ball mill at a feeding frequency of 8Hz. 3 The induced air flow of / h is transported to a classifier with a rotation speed of 2000rpm, and after classification, silicon micropowder with D50=11.4μm is obtained;

[0051] After mixing silicon micropowder and water in a mass ratio of 60:40, the mixture was pumped into a vertical stirred mill with a rotation speed of 260 rpm at a feed rate of 1500 L / min by a diaphragm pump, and part of the surface modifier (the mass ratio of part of the surface modifier to the remaining surface modifier was 2:1.5) was added through the top inlet of the vertical stirred mill. In the vertical stirred mill, the ball-to-material ratio was 51:49, and the mass ratio of 0.8-1 mm zirconia beads, 1.1-1.2 mm zirconia beads and 1.3-1.5 mm zirconia beads was 26:14:11. After grinding for 60 min, an ultrafine silicon micropowder slurry with D50 = 1.81 μm was obtained;

[0052] The ultrafine silicon micropowder slurry was flash dried at 350°C for 1.5 mm, and the dried product and the remaining surface modifier were modified at 114°C for 22 minutes, and then cooled to 25°C to obtain ultrafine active silicon micropowder.

[0053] Example 2

[0054] In this embodiment, the surface modifier is 3-(2,3-epoxypropoxy)propyltriethoxysilane, and the mass ratio of the surface modifier to the silicon powder is 0.8:100;

[0055] Fused quartz sand (whiteness 94%, magnetic impurity content 18ppm) was added to a continuously operating ball mill at a feeding frequency of 10 Hz. 3The induced air flow of / h is transported to a classifier with a rotation speed of 2200rpm, and after classification, silicon micropowder with D50=12.3μm is obtained;

[0056] After mixing silicon micropowder and water in a mass ratio of 64:36, the mixture was pumped into a vertical stirred mill with a rotation speed of 260 rpm at a feed rate of 1200 L / min by a diaphragm pump, and part of the surface modifier (the mass ratio of part of the surface modifier to the remaining surface modifier was 2:1) was added through the top inlet of the vertical stirred mill. In the vertical stirred mill, the ball-to-material ratio was 56:44, and the mass ratio of 0.8-1 mm zirconia beads, 1.1-1.2 mm zirconia beads, and 1.3-1.5 mm zirconia beads was 27:16:13. After grinding for 65 min, an ultrafine silicon micropowder slurry with D50 = 2.02 μm was obtained;

[0057] The ultrafine silicon micropowder slurry was flash dried at 320°C for 2 mm, the dried product and the remaining surface modifier were modified at 110°C for 15 minutes, and then cooled to 25°C to obtain ultrafine active silicon micropowder.

[0058] Example 3

[0059] In this embodiment, the surface modifier is 3-aminopropyltrimethoxysilane, and the mass ratio of the surface modifier to the silicon powder is 0.7:100;

[0060] E-glass sand (whiteness 94%, magnetic impurity content 18ppm) was added to a continuously running ball mill at a feeding frequency of 10 Hz. 3 The induced air flow of / h is transported to a classifier with a rotation speed of 2200rpm, and after classification, silicon micropowder with D50=10.1μm is obtained;

[0061] After mixing silicon micropowder and water in a mass ratio of 60:40, the mixture was pumped into a vertical stirred mill with a rotation speed of 260 rpm at a feed rate of 1200 L / min by a diaphragm pump, and part of the surface modifier (the mass ratio of part of the surface modifier to the remaining surface modifier was 2:2) was added through the top inlet of the vertical stirred mill. In the vertical stirred mill, the ball-to-material ratio was 48:52, and the mass ratio of 0.8-1 mm zirconia beads, 1.1-1.2 mm zirconia beads and 1.3-1.5 mm zirconia beads was 27:12:8. After grinding for 65 min, an ultrafine silicon micropowder slurry with a D50 of 1.78 μm was obtained;

[0062] The ultrafine silicon micropowder slurry was flash dried at 330°C for 1.5 mm, and the dried product and the remaining surface modifier were modified at 105°C for 12 minutes, and then cooled to 25°C to obtain ultrafine active silicon micropowder.

[0063] Performance testing:

[0064] The performance of the ultrafine active silicon powder prepared in Examples 1 to 3 was tested in accordance with GB / T19077-2016 Particle Size Analysis by Laser Diffraction Method and SJ / T10675-2002 Silicon Dioxide Powder for Electronic and Electrical Industries. The results are shown in Table 1.

[0065] Table 1 Performance test results of ultrafine active silicon powder prepared in Examples 1 to 3

[0066]

[0067] Combined with the performance test results shown in Table 1 Figures 2-4 It can be seen that the ultrafine active silicon micropowder prepared by the present invention has a whiteness of 96.7-97.8%, a magnetic impurity of 5-7 ppm, a particle size D50 of 1.7-2.1 μm, an oil absorption of 34-36 mL / 100 g, a moisture content of 0.08-0.13%, and an activation degree of 93.4-95.3%. It can be seen that the ultrafine active silicon micropowder prepared by the preparation method of the present invention has high whiteness, high fineness, low oil absorption, low moisture content, high activation degree and low magnetic impurity content, and can meet the application needs of high-tech industries.

[0068] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing ultrafine active silicon powder, characterized in that: The steps include: (1) mixing silicon micropowder, part of the surface modifier and water and grinding the mixture to obtain an ultrafine silicon micropowder slurry; (2) After the ultrafine silicon micropowder slurry is dried, it is mixed with the remaining surface modifier, modified, and then cooled to obtain ultrafine active silicon micropowder.

2. The method for preparing ultrafine active silicon powder according to claim 1, characterized in that: In the step (1), silicon micropowder is prepared by ball milling, air conveying and classification of ore-containing raw materials in sequence; The mineral raw material is natural quartz sand, fused quartz sand or alkali-free glass sand, the feeding frequency of the ball mill is 6-10 Hz, the medium of the ball mill is alumina ceramic, and the induced air volume of the air flow conveying is 12200-12800m 3 / h, the classification speed is 1900~2300rpm.

3. The method for preparing ultrafine active silicon powder according to claim 1, characterized in that: In the step (1), the particle size D50 of the silicon micropowder is 8 to 15 μm, and the mass ratio of the silicon micropowder to water is 50 to 70:30 to 50.

4. The method for preparing ultrafine active silicon powder according to claim 1 or 3, characterized in that: In the step (1), the grinding rotation speed is 220-300 rpm, and the particle size D50 of the solid particles in the ultrafine silicon micropowder slurry is less than 2.1 μm.

5. The method for preparing ultrafine active silicon powder according to claim 4, characterized in that: In the step (2), the modification temperature is 100-130°C, the modification time is 15-30 minutes, and the cooling temperature is 20-30°C.

6. The method for preparing ultrafine active silicon powder according to claim 5, characterized in that: The surface modifier is a vinyl silane coupling agent and / or an epoxy hydrocarbon silane coupling agent.

7. The method for preparing ultrafine active silicon powder according to claim 5 or 6, characterized in that: The mass ratio of the sum of the mass of part of the surface modifier and the remaining surface modifier to the mass of the silicon powder is 0.6-1.2:100; the mass ratio of part of the surface modifier to the remaining surface modifier is 2:1-2.

8. The ultrafine active silicon powder obtained by the method for preparing ultrafine active silicon powder according to any one of claims 1 to 7, characterized in that: The particle size D50 of the ultrafine active silicon powder is less than 2.1 μm.

Images