Spherical silica with low thixotropy and high fluidity, preparation method therefor and use thereof

Abstract

Provided in the present invention are a spherical silica with low thixotropy and high fluidity, a preparation method therefor and the use thereof, belonging to the technical field of silica. The present invention uses spherical silica with different particle sizes for particle size grading, and uses a coupling agent for wet modification treatment to obtain the spherical silica with low thixotropy and high fluidity. The results of examples show that after the spherical silica with low thixotropy and high fluidity provided by the present invention is added to an epoxy resin, the resulting composition has a thixotropic index of < 3 and a flow diameter of > 1.5 cm.

Description

A low-thixotropic, high-flowability spherical silica, its preparation method and application

[0001] This application claims priority to Chinese Patent Application No. 202411776133.8, filed on December 4, 2024, entitled "A Low-Thixotropic, High-Flowability Spherical Silica and Its Preparation Method and Application", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to the field of silica technology, and in particular to a low-thixotropic, high-flowability spherical silica, its preparation method, and its applications. Background Technology

[0003] As electronic products trend towards miniaturization, the semiconductor sealing structures used to encapsulate these products are also becoming thinner and smaller. Liquid epoxy encapsulants are representative encapsulation materials in microelectronics packaging technology. They are mainly composed of low-viscosity liquid alicyclic epoxy resin, spherical silica powder (silicon micropowder), epoxy curing agents, accelerators, silicon micropowder surface treatment agents, and other functional additives. However, the spherical silica powder in existing technologies has high thixotropy and poor flowability, which causes varying degrees of warping at the edges of electronic products encapsulated with liquid epoxy, thus affecting the usability of the electronic products. Therefore, there is an urgent need for a low-thixotropic, high-flowability spherical silica to solve the warping problem in electronic products encapsulated with liquid epoxy. Summary of the Invention

[0004] This invention provides a low-thixotropic, high-flow-rate spherical silica, prepared from a coupling agent, spherical silica, and a solvent. The D50 of the low-thixotropic, high-flow-rate spherical silica is 2–20 μm. The mass percentage of spherical silica with a particle size <5 μm is 15–70%, the mass percentage of spherical silica with a particle size ≤10 μm is 10–36%, and the mass percentage of spherical silica with a particle size <100 μm is 10–50%.

[0005] The present invention also provides a method for preparing the low thixotropic and high-flowability spherical silica described in the above technical solution, comprising: mixing a coupling agent, a solvent and spherical silica to obtain low thixotropic and high-flowability spherical silica.

[0006] The present invention also provides the application of the low thixotropic, high-flowability spherical silica described in the above technical solution or the low thixotropic, high-flowability spherical silica prepared according to the preparation method described in the above technical solution in liquid epoxy encapsulants. Detailed Implementation

[0007] This invention provides a low-thixotropic, high-flow-rate spherical silica, prepared from a coupling agent, spherical silica, and a solvent. The D50 of the low-thixotropic, high-flow-rate spherical silica is 2–20 μm. The mass percentage of spherical silica with a particle size <5 μm is 15–70%, the mass percentage of spherical silica with a particle size ≤10 μm is 10–36%, and the mass percentage of spherical silica with a particle size <100 μm is 10–50%.

[0008] In this invention, the D50 of the low-thixotropic, high-flowability spherical silica is 2–20 μm; the mass percentage of spherical silica with a particle size <5 μm in the low-thixotropic, high-flowability spherical silica is 15–70%; the mass percentage of spherical silica with a particle size ≤10 μm in the low-thixotropic, high-flowability spherical silica is 10–36%; and the mass percentage of spherical silica with a particle size ≤10 μm in the low-thixotropic, high-flowability spherical silica is 10–50%.

[0009] The spherical silica with low thixotropy and high fluidity provided by the present invention is a spherical silica that has been wet-modified by a coupling agent. By forming a particle size distribution through spherical silica with different particle sizes, it has low thixotropy and high fluidity.

[0010] The present invention also provides a method for preparing the low thixotropic, high-flowability spherical silica, comprising: mixing a coupling agent, a solvent and spherical silica to obtain low thixotropic, high-flowability spherical silica.

[0011] As one embodiment of the present invention, the method for preparing the low-thixotropic, high-flowability spherical silica may include the following steps:

[0012] The first spherical silica is mixed with a coupling agent and a solvent to obtain a coupling agent modified first spherical silica slurry.

[0013] The first spherical silica slurry modified with the coupling agent is mixed with the second and third spherical silica to obtain spherical silica with low thixotropy and high fluidity.

[0014] Unless otherwise specified, the present invention does not have any special limitations on the source of each raw material, and products prepared by commercially available products or conventional preparation methods known to those skilled in the art are acceptable.

[0015] In one embodiment of the present invention, the first spherical silica is mixed with a coupling agent and a solvent to obtain a coupling agent modified first spherical silica slurry.

[0016] In one embodiment of the present invention, the particle size of the first spherical silica can be 0 to 10 μm, and the D50 can be 0.1 to 3 μm.

[0017] In one embodiment of the present invention, the first spherical silica can be a single type of spherical silica with a D50 or a mixture of multiple types of spherical silica with a D50. In an embodiment of the present invention, the first spherical silica can be spherical silica with a D50 of 0.5 μm, a mixture of spherical silica with a D50 of 0.1 μm and D50 of 0.5 μm, a mixture of spherical silica with a D50 of 0.5 μm and D50 of 3 μm, or a mixture of spherical silica with a D50 of 0.1 μm, D50 of 0.5 μm and D50 of 3 μm.

[0018] In one embodiment of the present invention, when the first spherical silica is a mixture of spherical silica with a D50 of 0.1 μm and D50 of 0.5 μm, the mass ratio of the spherical silica with a D50 of 0.1 μm to the spherical silica with a D50 of 0.5 μm can be 10-30:70-90.

[0019] In one embodiment of the present invention, when the first spherical silica is a mixture of spherical silica with a D50 of 0.5 μm and D50 of 3 μm, the mass ratio of the spherical silica with a D50 of 0.5 μm to the spherical silica with a D50 of 3 μm can be 20-40:60-80.

[0020] In one embodiment of the present invention, when the first spherical silica is a mixture of spherical silica with a D50 of 0.1 μm, D50 of 0.5 μm and D50 of 3 μm, the mass ratio of the spherical silica with a D50 of 0.1 μm, the spherical silica with a D50 of 0.5 μm and the spherical silica with a D50 of 3 μm can be 10-30:20-40:20-50.

[0021] In one embodiment of the present invention, the coupling agent may be KH560 coupling agent.

[0022] In one embodiment of the present invention, the mass ratio of the coupling agent to the first spherical silica can be 0.005 to 0.05. In embodiments of the present invention, the mass ratio of the coupling agent to the first spherical silica can specifically be 0.005, 0.01, 0.02, 0.03, 0.04, or 0.05.

[0023] In one embodiment of the present invention, the solvent may be anhydrous ethanol.

[0024] In one embodiment of the present invention, the mass ratio of the coupling agent to the solvent can be 1:9 to 5:5. In specific embodiments of the present invention, the mass ratio of the coupling agent to the solvent can be 1:9, 2:8, 3:7, 4:6, or 5:5.

[0025] In one embodiment of the present invention, the first mixing may be: first mixing the coupling agent and the solvent, and then adding the first spherical silica for dispersion.

[0026] In one embodiment of the present invention, the dispersion can be carried out in an emulsifier, homogenizer or ball mill.

[0027] By controlling the dosage and other parameters of each raw material within the above-mentioned range, this invention can further improve the modification effect of the coupling agent and further improve the high fluidity and low thixotropy of spherical silica.

[0028] As one embodiment of the present invention, after obtaining the coupling agent modified first spherical silica slurry, the present invention can mix the coupling agent modified first spherical silica slurry with second spherical silica and third spherical silica to obtain spherical silica with low thixotropy and high fluidity.

[0029] In one embodiment of the present invention, the particle size of the second spherical silica can be 0–25 μm, and the D50 can be 5–8 μm. In the embodiments of the present invention, the D50 of the second spherical silica can specifically be 5 μm, 6 μm, 7 μm, or 8 μm.

[0030] In one embodiment of the present invention, the particle size of the third spherical silica can be 0–100 μm, and the D50 can be 9–30 μm. In the embodiments of the present invention, the D50 of the third spherical silica can specifically be 9 μm, 12 μm, 20 μm, 26 μm, or 30 μm.

[0031] In one embodiment of the present invention, the mass ratio of the first spherical silica, the second spherical silica, and the third spherical silica can be (15-70):(10-50):(10-50). The present invention controls the mass ratio of the three components within the above range, enabling particle size distribution of spherical silica with different particle sizes, further improving the high fluidity and low thixotropy of the spherical silica.

[0032] The present invention does not have any special limitations on the second mixing operation. The components can be mixed evenly by means of material mixing techniques known to those skilled in the art.

[0033] As one embodiment of the present invention, after the second mixing is completed, the product of the second mixing can be dried to obtain spherical silica with low thixotropy and high fluidity.

[0034] The present invention does not impose any particular limitation on the drying operation; any drying technique well-known to those skilled in the art can be used to remove the solvent. As one embodiment of the present invention, the drying can be carried out in a vibration dryer or a spray dryer.

[0035] This invention first uses a coupling agent to wet-modify the first spherical silica, and then adds the second and third spherical silica, which can improve the high fluidity and low thixotropy of the spherical silica.

[0036] The present invention also provides the application of the low thixotropic, high-flowability spherical silica described in the above technical solution or the low thixotropic, high-flowability spherical silica prepared according to the preparation method described in the above technical solution in liquid epoxy encapsulants.

[0037] The present invention does not impose any special limitations on the operation of the application, and any technical solution known to those skilled in the art can be used. Beneficial effects:

[0038] This invention provides a low-thixotropic, high-flow-rate spherical silica, prepared from a coupling agent, spherical silica, and a solvent. The D50 of the low-thixotropic, high-flow-rate spherical silica is 2–20 μm. The mass percentage of spherical silica with a particle size <5 μm is 15–70%, the mass percentage of spherical silica with a particle size between 5 μm and 10 μm is 10–36%, and the mass percentage of spherical silica with a particle size between 10 μm and 100 μm is 10–50%. This invention uses spherical silica of different particle sizes for particle size distribution and employs a coupling agent for wet modification to obtain spherical silica with low thixotropy and high flow-rate properties. The results of the examples show that when the low-thixotropic, high-flow-rate spherical silica provided by this invention is added to epoxy resin, the resulting composition has a thixotropy <3 and a flow diameter >1.5 cm.

[0039] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0040] Example 1

[0041] A low-thixotropic, high-flowability spherical silica with a D50 of 4.5 μm, comprising 38% by mass of spherical silica with a particle size < 5 μm, 36% by mass of spherical silica with a particle size ≤ 10 μm and a particle size < 100 μm, and 26% by mass of spherical silica with a particle size < 10 μm.

[0042] The preparation method of the low thixotropic and high flowability spherical silica is as follows: (1) KH560 coupling agent and anhydrous ethanol are mixed evenly in a mass ratio of 4:6 until clear, and then spherical silica with a D50 of 0.5μm and a particle size of 0 to 10μm is added. The mass ratio of coupling agent to spherical silica is 0.05. The homogenizer is used to disperse the slurry to obtain a uniformly dispersed slurry.

[0043] (2) Add spherical silica with a D50 of 6 μm and a particle size of 0-25 μm and spherical silica with a D50 of 12 μm and a particle size of 0-100 μm to the slurry obtained in step (1). After mixing evenly, dry it using a vibration dryer to obtain spherical silica with low thixotropy and high fluidity. The mass ratio of spherical silica with a D50 of 0.5 μm, spherical silica with a D50 of 6 μm and spherical silica with a D50 of 12 μm is 25:50:25.

[0044] Example 2

[0045] A low-thixotropic, high-flowability spherical silica with a D50 of 3.6 μm, comprising 40% by mass of spherical silica with a particle size < 5 μm, 35% by mass of spherical silica with a particle size ≤ 10 μm and a particle size < 100 μm, and 25% by mass of spherical silica with a particle size < 100 μm.

[0046] The preparation method of the low thixotropic and high flowability spherical silica is as follows: (1) KH560 coupling agent and anhydrous ethanol are mixed evenly until clear at a mass ratio of 3:7, and then spherical silica with a D50 of 0.5μm and a particle size of 0 to 10μm is added. The mass ratio of coupling agent to spherical silica is 0.02. The homogenizer is used to disperse the slurry to obtain a uniformly dispersed slurry.

[0047] (2) Add spherical silica with a D50 of 6 μm and a particle size of 0-25 μm and spherical silica with a D50 of 12 μm and a particle size of 0-100 μm to the slurry obtained in step (1). After mixing evenly, dry it using a vibration dryer to obtain spherical silica with low thixotropy and high fluidity. The mass ratio of spherical silica with a D50 of 0.5 μm, spherical silica with a D50 of 6 μm and spherical silica with a D50 of 12 μm is 25:50:25.

[0048] Example 3

[0049] A low-thixotropic, high-flowability spherical silica with a D50 of 4.3 μm, comprising 36% by mass of spherical silica with a particle size < 5 μm, 36% by mass of spherical silica with a particle size ≤ 10 μm and 28% by mass of spherical silica with a particle size ≤ 100 μm.

[0050] The preparation method of the low thixotropic and high flowability spherical silica is as follows: (1) KH560 coupling agent and anhydrous ethanol are mixed evenly at a mass ratio of 1:9 until clear, and then spherical silica with a D50 of 0.5μm and a particle size of 0 to 10μm is added. The mass ratio of coupling agent to spherical silica is 0.005. The homogenizer is used to disperse the slurry to obtain a uniformly dispersed slurry.

[0051] (2) Add spherical silica with a D50 of 6 μm and a particle size of 0-25 μm and spherical silica with a D50 of 12 μm and a particle size of 0-100 μm to the slurry obtained in step (1). After mixing evenly, dry it using a vibration dryer to obtain spherical silica with low thixotropy and high fluidity. The mass ratio of spherical silica with a D50 of 0.5 μm, spherical silica with a D50 of 6 μm and spherical silica with a D50 of 12 μm is 25:50:25.

[0052] Example 4

[0053] A low-thixotropic, high-flowability spherical silica with a D50 of 2.7 μm, comprising 70% by mass of spherical silica with a particle size < 5 μm, 13% by mass of spherical silica with a particle size ≤ 10 μm and a particle size < 100 μm, and 17% by mass of spherical silica with a particle size < 10 μm.

[0054] The preparation method of the low thixotropic and high flowability spherical silica is as follows: (1) KH560 coupling agent and anhydrous ethanol are mixed evenly until clear at a mass ratio of 1:9. Then, spherical silica with D50 of 0.1μm and particle size of 0-10μm and spherical silica with D50 of 0.5μm and particle size of 0-10μm are added. The mass ratio of spherical silica with D50 of 0.1μm and spherical silica with D50 of 0.5μm is 1:3. The mass ratio of coupling agent to total mass of spherical silica with D50 of 0.1μm and D50 of 0.5μm is 0.02. The homogenizer is used to disperse the slurry to obtain a uniformly dispersed slurry.

[0055] (2) Add spherical silica with a D50 of 6 μm and a particle size of 0-25 μm and spherical silica with a D50 of 12 μm and a particle size of 0-100 μm to the slurry obtained in step (1). After mixing evenly, dry it using a vibration dryer to obtain spherical silica with low thixotropy and high fluidity. The total mass ratio of spherical silica with a D50 of 0.1 μm and D50 of 0.5 μm to the mass ratio of spherical silica with a D50 of 6 μm and D50 of 12 μm is 40:40:20.

[0056] Example 5

[0057] A low-thixotropic, high-flowability spherical silica with a D50 of 6.8 μm, wherein the mass percentage of spherical silica with a particle size < 5 μm is 32%, the mass percentage of spherical silica with a particle size ≤ 10 μm is 29%, and the mass percentage of spherical silica with a particle size ≤ 100 μm is 39%.

[0058] The preparation method of the low thixotropic and high flowability spherical silica is as follows: (1) KH560 coupling agent and anhydrous ethanol are mixed evenly until clear at a mass ratio of 1:9. Then, spherical silica with a D50 of 0.5μm and a particle size of 0-10μm and spherical silica with a D50 of 3μm and a particle size of 0-10μm are added. The mass ratio of spherical silica with a D50 of 0.5μm and spherical silica with a D50 of 3μm is 1:2. The mass ratio of the coupling agent to the total mass of spherical silica with a D50 of 0.5μm and D50 of 3μm is 0.02. The homogenizer is used to disperse the slurry to obtain a uniformly dispersed slurry.

[0059] (2) Add spherical silica with a D50 of 6 μm and a particle size of 0-25 μm and spherical silica with a D50 of 12 μm and a particle size of 0-100 μm to the slurry obtained in step (1). After mixing evenly, dry it using a vibration dryer to obtain spherical silica with low thixotropy and high fluidity. The total mass ratio of spherical silica with a D50 of 0.5 μm and D50 of 3 μm to the mass ratio of spherical silica with a D50 of 6 μm and D50 of 12 μm is 30:40:30.

[0060] Example 6

[0061] A low-thixotropic, high-flowability spherical silica with a D50 of 7.8 μm, comprising 56% by mass of spherical silica with a particle size < 5 μm, 16% by mass of spherical silica with a particle size ≤ 10 μm and a particle size < 100 μm, and 28% by mass of spherical silica with a particle size < 10 μm and a particle size < 100 μm.

[0062] The preparation method of the low thixotropic and high flowability spherical silica is as follows: (1) KH560 coupling agent and anhydrous ethanol are mixed evenly in a mass ratio of 1:9 until clear, and then spherical silica with D50 of 0.1μm and particle size of 0-10μm, spherical silica with D50 of 0.5μm and particle size of 0-10μm, and spherical silica with D50 of 3μm and particle size of 0-10μm are added. The mass ratio of spherical silica with D50 of 0.1μm, spherical silica with D50 of 0.5μm and spherical silica with D50 of 3μm is 1:2:2. The mass ratio of the coupling agent to the total mass of spherical silica with D50 of 0.1μm, D50 of 0.5μm and D50 of 3μm is 0.02. The slurry is dispersed using a homogenizer to obtain a uniformly dispersed slurry.

[0063] (2) Add spherical silica with a D50 of 6 μm and a particle size of 0-25 μm and spherical silica with a D50 of 26 μm and a particle size of 0-100 μm to the slurry obtained in step (1). After mixing evenly, dry it using a vibration dryer to obtain spherical silica with low thixotropy and high fluidity. The total mass ratio of spherical silica with D50 of 0.1 μm, D50 of 0.5 μm and D50 of 3 μm to the mass ratio of spherical silica with D50 of 6 μm and spherical silica with D50 of 26 μm is 50:20:30.

[0064] Example 7

[0065] A low-thixotropic, high-flowability spherical silica with a D50 of 16.4 μm, comprising 17% by mass of spherical silica with a particle size < 5 μm, 33% by mass of spherical silica with a particle size ≤ 10 μm and a particle size < 100 μm, and 50% by mass of spherical silica with a particle size < 10 μm and a particle size < 100 μm.

[0066] The preparation method of the low thixotropic, high-flowability spherical silica is as follows: (1) KH560 coupling agent and anhydrous ethanol are mixed evenly at a mass ratio of 1:9 until clear, and then spherical silica with a D50 of 0.5 μm and a particle size of 0-10 μm and spherical silica with a D50 of 3 μm and a particle size of 0-10 μm are added.

[0067] The mass ratio of spherical silica is 2:3, and the mass ratio of coupling agent to the total mass of spherical silica with D50 of 0.5μm and D50 of 3μm is 0.02. A homogenizer is used to disperse the slurry to obtain a uniformly dispersed slurry.

[0068] (2) Add spherical silica with a D50 of 6 μm and a particle size of 0-25 μm and spherical silica with a D50 of 26 μm and a particle size of 0-100 μm to the slurry obtained in step (1). After mixing evenly, dry it using a vibration dryer to obtain spherical silica with low thixotropy and high fluidity. The total mass ratio of spherical silica with a D50 of 0.5 μm and D50 of 3 μm to the mass ratio of spherical silica with a D50 of 6 μm and D50 of 26 μm is 25:35:40.

[0069] Comparative Example 1

[0070] Spherical silica with a D50 of 0.5 μm and a particle size of 0–10 μm, spherical silica with a D50 of 6 μm and a particle size of 0–25 μm, and spherical silica with a D50 of 12 μm and a particle size of 0–100 μm were dry-mixed at a mass ratio of 38:36:26 to obtain a powder. KH560 coupling agent was added for dry surface treatment (mass ratio of coupling agent to powder was 0.02) to obtain spherical silica with a D50 of 4.5 μm.

[0071] Comparative Example 2

[0072] Spherical silica with a D50 of 0.5 μm and a particle size of 0–10 μm, spherical silica with a D50 of 3 μm and a particle size of 0–10 μm, spherical silica with a D50 of 6 μm and a particle size of 0–25 μm, and spherical silica with a D50 of 12 μm and a particle size of 0–100 μm were dry-mixed according to the mass ratio in Example 7 to obtain powder. KH560 coupling agent was added for dry surface treatment (mass ratio of coupling agent to powder was 0.02) to obtain spherical silica with a D50 of 18.3 μm.

[0073] Comparative Example 3

[0074] A spherical silica with a D50 of 24.3 μm, wherein the mass percentage of spherical silica with a particle size < 5 μm is 10%, the mass percentage of spherical silica with a particle size ≤ 10 μm is 12%, and the mass percentage of spherical silica with a particle size ≤ 10 μm is 78%.

[0075] The preparation method of the spherical silica is as follows: KH560 coupling agent and anhydrous ethanol are mixed evenly until clear at a mass ratio of 1:9. Then, spherical silica with a D50 of 0.5 μm and a particle size of 0–10 μm and spherical silica with a D50 of 3 μm and a particle size of 0–10 μm are added. The mass ratio of spherical silica with a D50 of 0.5 μm and spherical silica with a D50 of 3 μm is 2:3. The mass ratio of the coupling agent to the particle size of the spherical silica is... The total mass ratio of spherical silica with a D50 of 0.5 μm and a D50 of 3 μm was 0.02, and the mixture was dispersed using a homogenizer to obtain a uniformly dispersed slurry. Spherical silica with a D50 of 6 μm and a particle size of 0–50 μm and a D50 of 38 μm and a particle size of 0–150 μm were added to the slurry, and after being mixed evenly, the mixture was dried using a vibration dryer to obtain spherical silica with a D50 of 24.3 μm.

[0076] Comparative Example 4

[0077] Spherical silica with a D50 of 0.5 μm and a particle size of 0–10 μm, spherical silica with a D50 of 6 μm and a particle size of 0–25 μm, and spherical silica with a D50 of 12 μm and a particle size of 0–100 μm were mixed in a ratio of 25:50:25. KH560 coupling agent and anhydrous ethanol were mixed evenly and clarified at a mass ratio of 3:7. The mixed powder was then added, with the mass ratio of coupling agent to spherical silica being 0.02. The mixture was dispersed using a homogenizer to obtain a uniformly dispersed slurry. The slurry was then dried using a vibrating dryer to obtain spherical silica with a D50 of 4.0 μm. The mass percentage of spherical silica with a particle size <5 μm was 37%, and the mass percentage of spherical silica with a particle size <10 μm and <100 μm was 25%.

[0078] The spherical silica products prepared in Examples 1-7 and Comparative Examples 1-4 were mixed with bisphenol F epoxy resin (the mass ratio of spherical silica product to bisphenol F epoxy resin was 0.85). After dispersion using a planetary ball mill, isothermal variable shear tests were performed using a rheometer to obtain the corresponding rheological curves, and the corresponding 10s values ​​were recorded. -1 and 100s -1 Viscosity value A 10 -1, A 100 -1, its thixotropy (A) was measured at 25℃. 10 -1 / A 100 -1), the results are shown in Table 1.

[0079] Using a 10mL disposable syringe, 1mL of a uniformly dispersed spherical silica product and bisphenol F epoxy resin composition was drawn and vertically extruded onto a smooth glass slide cleaned with ethanol and kept at a constant temperature of 25°C. The flow diameter of the composition was recorded after 1 minute, and the powder flowability was measured.

[0080] The cumulative 50% particle size (D50) of the volume standard was determined using laser diffraction scattering particle size distribution.

[0081] Table 1. Particle size distribution of spherical silica products in Examples 1-7 and Comparative Examples 1-4, and thixotropic and flow diameters of spherical silica products mixed with bisphenol F epoxy resin in Examples 1-7 and Comparative Examples 1-4.

[0082] As can be seen from Table 1, the spherical silica provided by this invention exhibits low thixotropy and high flowability. Under comparable particle size conditions, thixotropy and flowability increase with increasing coupling agent content. Therefore, when D50 = 3-4 μm, Example 2 shows better performance. Under comparable D50 conditions, thixotropy increases and flowability decreases with increasing <5 μm powder content; compared to Example 6, Example 5 shows better performance. Under comparable D50 conditions, wet modification reduces thixotropy and increases flowability compared to dry modification; compared to Comparative Example 2, Example 7 shows better performance. Comparative Example 3 shows that when the D50 and particle size distribution of the spherical silica are outside the range of this invention, its flowability deteriorates and thixotropy increases. Comparative Example 4 shows that firstly modifying the small-particle-size spherical silica raw material can improve the flowability of the product and reduce thixotropy.

[0083] The above description of the embodiments is merely for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A low-thixotropic, high-flow-rate spherical silica, prepared from a coupling agent, spherical silica, and a solvent; wherein the D50 of the low-thixotropic, high-flow-rate spherical silica is 2–20 μm, and the mass percentage of spherical silica with a particle size <5 μm is 15–70%, the mass percentage of spherical silica with a particle size ≤10 μm is 10–36%, and the mass percentage of spherical silica with a particle size ≤100 μm is 10–50%.

2. The method for preparing the low-thixotropic, high-flowability spherical silica according to claim 1, comprising: By mixing coupling agent, solvent and spherical silica, spherical silica with low thixotropy and high fluidity is obtained.

3. The preparation method according to claim 2, characterized in that, The mass ratio of the coupling agent to the solvent is 1:9 to 5:

5.

4. The production method according to claim 2, characterized by, The method for preparing the low-thixotropic, high-flowability spherical silica includes the following steps: The first spherical silica is mixed with a coupling agent and a solvent to obtain a coupling agent modified first spherical silica slurry. The first spherical silica slurry modified with the coupling agent is mixed with the second and third spherical silica to obtain spherical silica with low thixotropy and high fluidity.

5. The preparation method according to claim 4, characterized in that, The first spherical silica has a particle size of 0–10 μm and a D50 of 0.1–3 μm.

6. The preparation method according to claim 4 or 5, characterized in that, The mass ratio of the coupling agent to the first spherical silica is 0.005 to 0.

05.

7. The preparation method according to claim 4, characterized in that, The particle size of the second spherical silica is 0–25 μm, and the D50 is 5–8 μm.

8. The preparation method according to claim 4, characterized in that, The particle size of the third spherical silica is 0–100 μm, and the D50 is 9–30 μm.

9. The preparation method according to claim 4, characterized in that, The mass ratio of the first spherical silica, the second spherical silica, and the third spherical silica is (15-70):(10-50):(10-50).

10. The application of the low-thixotropic, high-flowability spherical silica according to claim 1 or the low-thixotropic, high-flowability spherical silica prepared according to any one of claims 2 to 9 in liquid epoxy encapsulants.

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