Spherical silicon dioxide with low thixotropy and high fluidity as well as preparation method and application of spherical silicon dioxide

Abstract

The invention provides low-thixotropy and high-fluidity spherical silicon dioxide as well as a preparation method and application thereof, and belongs to the technical field of silicon dioxide. The spherical silicon dioxide with low thixotropy and high fluidity is obtained by carrying out grain size distribution on spherical silicon dioxide with different grain sizes and carrying out wet modification treatment by adopting a coupling agent. Results of the embodiment show that when the low-thixotropy and high-fluidity spherical silicon dioxide provided by the invention is added into epoxy resin, the thixotropy of the obtained composition is less than 3, and the flow diameter is more than 1.5 cm.

Description

Technical Field

[0001] The invention belongs to the technical field of silicon dioxide, and in particular relates to spherical silicon dioxide with low thixotropy and high fluidity, and a preparation method and application thereof. Background Art

[0002] As electronic products develop towards miniaturization, the semiconductor sealing structure used to package electronic products has also embarked on the road of being thin, light and short. Liquid epoxy encapsulation material is a representative packaging material of microelectronic packaging technology. It is mainly prepared from low-viscosity liquid alicyclic epoxy resin, spherical silica powder (silicon powder), epoxy curing agent, accelerator, silicon powder surface treatment agent and other functional additives. However, the spherical silica powder in the prior art has high thixotropy and poor fluidity, which causes the edges of electronic products encapsulated by liquid epoxy encapsulation material to warp to varying degrees, thereby affecting the use of electronic products. Therefore, there is an urgent need for a spherical silica with low thixotropy and high fluidity to solve the problem of warping of electronic products encapsulated by liquid epoxy encapsulation material. Summary of the invention

[0003] The object of the present invention is to provide a spherical silicon dioxide with low thixotropy and high fluidity and a preparation method and application thereof. The spherical silicon dioxide provided by the present invention has low thixotropy and high fluidity.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The invention provides a spherical silica with low thixotropy and high fluidity, which is prepared from a coupling agent, spherical silica and a solvent; the D50 of the spherical silica with low thixotropy and high fluidity is 2-20 μm, the mass percentage of spherical silica with a particle size of less than 5 μm in the spherical silica with low thixotropy and high fluidity is 15-70%, the mass percentage of spherical silica with a particle size of 5 μm≤≤10 μm is 10-36%, and the mass percentage of spherical silica with a particle size of 10 μm<<100 μm is 10-50%.

[0006] Preferably, the spherical silica includes a first spherical silica, a second spherical silica and a third spherical silica.

[0007] Preferably, the particle size of the first spherical silica is 0-10 μm, and D50 is 0.1-3 μm.

[0008] Preferably, the particle size of the second spherical silica is 0-25 μm, and D50 is 5-8 μm.

[0009] Preferably, the particle size of the third spherical silica is 0-100 μm, and D50 is 9-30 μm.

[0010] The present invention also provides a method for preparing the low thixotropic and high fluidity spherical silica described in the above technical solution, comprising:

[0011] The coupling agent, the solvent and the spherical silica are mixed to obtain the spherical silica with low thixotropy and high fluidity.

[0012] Preferably, the method for preparing the low thixotropic and high fluidity spherical silica comprises the following steps:

[0013] (1) mixing a first spherical silica with a coupling agent and a solvent to obtain a coupling agent-modified first spherical silica slurry;

[0014] (2) The coupling agent-modified first spherical silica slurry obtained in step (1) is mixed with the second spherical silica and the third spherical silica to obtain spherical silica with low thixotropy and high fluidity.

[0015] Preferably, in step (1), the mass ratio of the coupling agent to the first spherical silica is 0.005 to 0.05.

[0016] Preferably, the mass ratio of the first spherical silica in step (1), the second spherical silica and the third spherical silica in step (2) is (15-70): (10-50): (10-50).

[0017] The present invention also provides the use of the low thixotropic, high fluidity spherical silica described in the above technical solution or the low thixotropic, high fluidity spherical silica prepared by the preparation method described in the above technical solution in liquid epoxy packaging materials.

[0018] The present invention provides a spherical silica with low thixotropy and high fluidity, which is prepared by a coupling agent, spherical silica and a solvent; the D50 of the spherical silica with low thixotropy and high fluidity is 2-20 μm, the mass percentage of spherical silica with a particle size of less than 5 μm in the spherical silica with low thixotropy and high fluidity is 15-70%, the mass percentage of spherical silica with a particle size of 5 μm≤particle size≤10 μm is 10-36%, and the mass percentage of spherical silica with a particle size of 10 μm<particle size<100 μm is 10-50%. 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 spherical silica with low thixotropy and high fluidity. The results of the embodiment show that when the spherical silica with low thixotropy and high fluidity provided by the present invention is added to epoxy resin, the thixotropy of the obtained composition is less than 3, and the flow diameter is greater than 1.5 cm. DETAILED DESCRIPTION

[0019] The invention provides a spherical silica with low thixotropy and high fluidity, which is prepared from a coupling agent, spherical silica and a solvent; the D50 of the spherical silica with low thixotropy and high fluidity is 2-20 μm, the mass percentage of spherical silica with a particle size of less than 5 μm in the spherical silica with low thixotropy and high fluidity is 15-70%, the mass percentage of spherical silica with a particle size of 5 μm≤≤10 μm is 10-36%, and the mass percentage of spherical silica with a particle size of 10 μm<<100 μm is 10-50%.

[0020] In the present invention, the spherical silica preferably includes a first spherical silica, a second spherical silica, and a third spherical silica.

[0021] In the present invention, the particle size of the first spherical silica is preferably 0-10 μm, and D50 is preferably 0.1-3 μm. In the present invention, the first spherical silica is preferably a spherical silica of a single D50 or a mixture of spherical silicas of multiple D50s.

[0022] In the present invention, the particle size of the second spherical silica is preferably 0 to 25 μm, and D50 is preferably 5 to 8 μm.

[0023] In the present invention, the particle size of the third spherical silica is preferably 0 to 100 μm, and D50 is preferably 9 to 30 μm.

[0024] In the present invention, the D50 of the low thixotropic, high fluidity spherical silica is 2 to 20 μm; the mass percentage of spherical silica with a particle size of less than 5 μm in the low thixotropic, high fluidity spherical silica is 15 to 70%; the mass percentage of spherical silica with a particle size of 5 μm ≤ ≤ 10 μm in the low thixotropic, high fluidity spherical silica is 10 to 36%; the mass percentage of spherical silica with a particle size of 10 μm < < 100 μm in the low thixotropic, high fluidity spherical silica is 10 to 50%.

[0025] The invention adopts spherical silicon dioxide with different particle diameters for particle size grading, and adopts a coupling agent for wet modification treatment to obtain spherical silicon dioxide with low thixotropy and high fluidity.

[0026] The present invention also provides a method for preparing the low thixotropic and high fluidity spherical silica described in the above technical solution, comprising:

[0027] The coupling agent, the solvent and the spherical silica are mixed to obtain the spherical silica with low thixotropy and high fluidity.

[0028] In the present invention, the method for preparing the low thixotropic and high fluidity spherical silica preferably comprises the following steps:

[0029] (1) mixing a first spherical silica with a coupling agent and a solvent to obtain a coupling agent-modified first spherical silica slurry;

[0030] (2) The coupling agent-modified first spherical silica slurry obtained in step (1) is mixed with the second spherical silica and the third spherical silica to obtain spherical silica with low thixotropy and high fluidity.

[0031] Unless otherwise specified, the present invention has no particular limitation on the sources of the raw materials, and any commercially available product or product prepared by a conventional preparation method well known to those skilled in the art may be used.

[0032] In the present invention, the first spherical silica is preferably mixed with a coupling agent and a solvent for modification to obtain a coupling agent-modified first spherical silica slurry.

[0033] In the present invention, the particle size of the first spherical silica is preferably 0 to 10 μm, and D50 is preferably 0.1 to 3 μm.

[0034] In the present invention, the first spherical silica is preferably a single spherical silica of D50 or a mixture of spherical silicas of multiple D50s. In an embodiment of the present invention, the first spherical silica may be specifically a spherical silica of D50 of 0.5 μm, a mixture of spherical silicas of D50 of 0.1 μm and D50 of 0.5 μm, a mixture of spherical silicas of D50 of 0.5 μm and D50 of 3 μm, or a mixture of spherical silicas of D50 of 0.1 μm, D50 of 0.5 μm and D50 of 3 μm.

[0035] In the present invention, when the first spherical silica is a mixture of spherical silica with D50 of 0.1 μm and spherical silica with D50 of 0.5 μm, the mass ratio of the spherical silica with D50 of 0.1 μm to the spherical silica with D50 of 0.5 μm is preferably 10-30:70-90.

[0036] In the present invention, when the first spherical silica is a mixture of spherical silica with D50 of 0.5 μm and spherical silica with D50 of 3 μm, the mass ratio of the spherical silica with D50 of 0.5 μm to the spherical silica with D50 of 3 μm is preferably 20-40:60-80.

[0037] In the present invention, when the first spherical silica is a mixture of spherical silica with D50 of 0.1 μm, 0.5 μm and 3 μm, the mass ratio of the spherical silica with D50 of 0.1 μm, the spherical silica with D50 of 0.5 μm and the spherical silica with D50 of 3 μm is preferably 10-30:20-40:20-50.

[0038] In the present invention, the coupling agent is preferably KH560 coupling agent.

[0039] In the present invention, the mass ratio of the coupling agent to the first spherical silica is preferably 0.005 to 0.05. In an embodiment of the present invention, the mass ratio of the coupling agent to the first spherical silica can be specifically 0.005, 0.01, 0.02, 0.03, 0.04 or 0.05.

[0040] In the present invention, the solvent is preferably anhydrous ethanol.

[0041] In the present invention, the mass ratio of the coupling agent to the solvent is preferably 1:9 to 5:5. In an embodiment of the present invention, the mass ratio of the coupling agent to the solvent can be specifically 1:9, 2:8, 3:7, 4:6, or 5:5.

[0042] In the present invention, the mixing of the first spherical silica with the coupling agent and the solvent is preferably carried out by mixing the coupling agent and the solvent, and then adding the first spherical silica.

[0043] In the present invention, the mixing is preferably performed in an emulsifier, a homogenizer or a ball mill.

[0044] The present invention controls the parameters such as the amount of each raw material within the above range, which can further improve the modification effect of the coupling agent and further improve the high fluidity and low thixotropy of the spherical silica.

[0045] After obtaining the first spherical silica slurry modified by the coupling agent, the present invention preferably mixes the first spherical silica slurry modified by the coupling agent with the second spherical silica and the third spherical silica to obtain spherical silica with low thixotropy and high fluidity.

[0046] In the present invention, the particle size of the second spherical silica is preferably 0-25 μm, and D50 is preferably 5-8 μm. In an embodiment of the present invention, D50 of the second spherical silica may specifically be 5 μm, 6 μm, 7 μm or 8 μm.

[0047] In the present invention, the particle size of the third spherical silica is preferably 0-100 μm, and D50 is preferably 9-30 μm. In an embodiment of the present invention, D50 of the third spherical silica may specifically be 9 μm, 12 μm, 20 μm, 26 μm or 30 μm.

[0048] In the present invention, the mass ratio of the first spherical silica, the second spherical silica and the third spherical silica is preferably (15-70): (10-50): (10-50). The present invention controls the mass ratio of the three within the above range, so that spherical silica with different particle sizes is graded, further improving the high fluidity and low thixotropy of the spherical silica.

[0049] The present invention has no special limitation on the mixing operation of the coupling agent-modified first spherical silica slurry with the second spherical silica and the third spherical silica. The components can be uniformly mixed using a material mixing technical solution well known to those skilled in the art.

[0050] After the mixing is completed, the present invention preferably dries the mixed product to obtain spherical silica with low thixotropy and high fluidity.

[0051] The present invention has no special limitation on the drying operation, and the drying technical schemes well known to those skilled in the art can be adopted. In the present invention, the drying is preferably carried out in a vibration dryer or a spray dryer.

[0052] The invention firstly uses a coupling agent to modify a first spherical silica with a small particle size, and then adds a second spherical silica and a third spherical silica with larger particle sizes, thereby improving the high fluidity and low thixotropy of the spherical silica.

[0053] The present invention also provides the use of the low thixotropic, high fluidity spherical silica described in the above technical solution or the low thixotropic, high fluidity spherical silica prepared by the preparation method described in the above technical solution in liquid epoxy packaging materials.

[0054] The present invention has no special limitation on the operation of the application, and the technical solutions of the application well known to those skilled in the art may be adopted.

[0055] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. 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.

[0056] Example 1

[0057] A spherical silica with low thixotropy and high fluidity, wherein D50 is 4.5 μm, the mass percentage of spherical silica with a particle size of less than 5 μm is 38%, the mass percentage of spherical silica with a particle size of 5 μm≤≤10 μm is 36%, and the mass percentage of spherical silica with a particle size of 10 μm<<100 μm is 26%;

[0058] The preparation method of the low thixotropic and high fluidity spherical silica is as follows: (1) KH560 coupling agent and anhydrous ethanol are mixed uniformly in a mass ratio of 4:6 until clarified, spherical silica with a D50 of 0.5 μm and a particle size of 0 to 10 μm is added, the mass ratio of the coupling agent to the spherical silica is 0.05, and a homogenizer is used for dispersion to obtain a uniformly dispersed slurry;

[0059] (2) Spherical silica with a D50 of 6 μm and a particle size of 0 to 25 μm and spherical silica with a D50 of 12 μm and a particle size of 0 to 100 μm are added to the slurry obtained in step (1), mixed evenly and dried using a vibration dryer to obtain low thixotropic and high fluidity spherical silica, wherein the mass ratio of the spherical silica with a D50 of 0.5 μm, the spherical silica with a D50 of 6 μm and the spherical silica with a D50 of 12 μm is 25:50:25.

[0060] Example 2

[0061] A spherical silica with low thixotropy and high fluidity, wherein D50 is 3.6 μm, the mass percentage of spherical silica with a particle size of less than 5 μm is 40%, the mass percentage of spherical silica with a particle size of 5 μm≤≤10 μm is 35%, and the mass percentage of spherical silica with a particle size of 10 μm<<100 μm is 25%;

[0062] The preparation method of the low thixotropic and high fluidity spherical silica is as follows: (1) KH560 coupling agent and anhydrous ethanol are mixed uniformly in a mass ratio of 3:7 until the mixture is clarified, spherical silica with a D50 of 0.5 μm and a particle size of 0 to 10 μm is added, the mass ratio of the coupling agent to the spherical silica is 0.02, and a homogenizer is used for dispersion to obtain a uniformly dispersed slurry;

[0063] (2) Spherical silica with a D50 of 6 μm and a particle size of 0 to 25 μm and spherical silica with a D50 of 12 μm and a particle size of 0 to 100 μm are added to the slurry obtained in step (1), mixed evenly and dried using a vibration dryer to obtain low thixotropic and high fluidity spherical silica, wherein the mass ratio of the spherical silica with a D50 of 0.5 μm, the spherical silica with a D50 of 6 μm and the spherical silica with a D50 of 12 μm is 25:50:25.

[0064] Example 3

[0065] A spherical silica with low thixotropy and high fluidity, wherein D50 is 4.3 μm, the mass percentage of spherical silica with a particle size of less than 5 μm is 36%, the mass percentage of spherical silica with a particle size of 5 μm≤≤10 μm is 36%, and the mass percentage of spherical silica with a particle size of 10 μm<<100 μm is 28%;

[0066] The preparation method of the low thixotropic and high fluidity spherical silica is as follows: (1) KH560 coupling agent and anhydrous ethanol are mixed uniformly in a mass ratio of 1:9 until clarified, spherical silica with a D50 of 0.5 μm and a particle size of 0 to 10 μm is added, the mass ratio of the coupling agent to the spherical silica is 0.005, and a homogenizer is used for dispersion to obtain a uniformly dispersed slurry;

[0067] (2) Spherical silica with a D50 of 6 μm and a particle size of 0 to 25 μm and spherical silica with a D50 of 12 μm and a particle size of 0 to 100 μm are added to the slurry obtained in step (1), mixed evenly and dried using a vibration dryer to obtain low thixotropic and high fluidity spherical silica, wherein the mass ratio of the spherical silica with a D50 of 0.5 μm, the spherical silica with a D50 of 6 μm and the spherical silica with a D50 of 12 μm is 25:50:25.

[0068] Example 4

[0069] A spherical silica with low thixotropy and high fluidity, wherein D50 is 2.7 μm, the mass percentage of spherical silica with a particle size of less than 5 μm is 70%, the mass percentage of spherical silica with a particle size of 5 μm≤≤10 μm is 13%, and the mass percentage of spherical silica with a particle size of 10 μm<<100 μm is 17%;

[0070] The preparation method of the low thixotropic and high fluidity spherical silica is as follows: (1) KH560 coupling agent and anhydrous ethanol are mixed uniformly in a mass ratio of 1:9 until clarified, and spherical silica with a D50 of 0.1 μm and a particle size of 0 to 10 μm and a D50 of 0.5 μm and a particle size of 0 to 10 μm are added, 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 is 1:3, the total mass ratio of the mass of the coupling agent to the mass of the spherical silica with a D50 of 0.1 μm and the mass of the spherical silica with a D50 of 0.5 μm is 0.02, and a homogenizer is used for dispersion to obtain a uniformly dispersed slurry;

[0071] (2) Spherical silica with a D50 of 6 μm and a particle size of 0 to 25 μm and spherical silica with a D50 of 12 μm and a particle size of 0 to 100 μm are added to the slurry obtained in step (1), mixed evenly and dried using a vibration dryer to obtain low thixotropic and high fluidity spherical silica, wherein the mass ratio of the total mass of the spherical silica with a D50 of 0.1 μm and the spherical silica with a D50 of 0.5 μm to the mass ratio of the spherical silica with a D50 of 6 μm and the spherical silica with a D50 of 12 μm is 40:40:20.

[0072] Example 5

[0073] A spherical silica with low thixotropy and high fluidity, wherein D50 is 6.8 μm, the mass percentage of spherical silica with a particle size of less than 5 μm is 32%, the mass percentage of spherical silica with a particle size of 5 μm≤≤10 μm is 29%, and the mass percentage of spherical silica with a particle size of 10 μm<<100 μm is 39%;

[0074] The preparation method of the low thixotropic and high fluidity spherical silica is as follows: (1) KH560 coupling agent and anhydrous ethanol are mixed uniformly in a mass ratio of 1:9 until clarified, and spherical silica with a D50 of 0.5 μm and a particle size of 0 to 10 μm and a D50 of 3 μm and a particle size of 0 to 10 μm are added, the mass ratio of the spherical silica with a D50 of 0.5 μm to the spherical silica with a D50 of 3 μm is 1:2, the total mass ratio of the mass of the coupling agent to the mass of the spherical silica with a D50 of 0.5 μm and the mass of the spherical silica with a D50 of 3 μm is 0.02, and a homogenizer is used for dispersion to obtain a uniformly dispersed slurry;

[0075] (2) Spherical silica with a D50 of 6 μm and a particle size of 0 to 25 μm and spherical silica with a D50 of 12 μm and a particle size of 0 to 100 μm are added to the slurry obtained in step (1), mixed evenly and dried using a vibration dryer to obtain low thixotropic and high fluidity spherical silica, wherein the mass ratio of the total mass of the spherical silica with a D50 of 0.5 μm and the spherical silica with a D50 of 3 μm to the mass ratio of the spherical silica with a D50 of 6 μm and the spherical silica with a D50 of 12 μm is 30:40:30.

[0076] Example 6

[0077] A spherical silica with low thixotropy and high fluidity, wherein D50 is 7.8 μm, the mass percentage of spherical silica with a particle size of less than 5 μm is 56%, the mass percentage of spherical silica with a particle size of 5 μm≤≤10 μm is 16%, and the mass percentage of spherical silica with a particle size of 10 μm<<100 μm is 28%;

[0078] The preparation method of the low thixotropic and high fluidity spherical silica is as follows: (1) KH560 coupling agent and anhydrous ethanol are mixed uniformly in a mass ratio of 1:9 until clarified, and spherical silica with a D50 of 0.1 μm and a particle size of 0 to 10 μm, spherical silica with a D50 of 0.5 μm and a particle size of 0 to 10 μm, and spherical silica with a D50 of 3 μm and a particle size of 0 to 10 μm are added, 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 is 1:2:2, the total mass ratio of the mass of the coupling agent to the spherical silica with a D50 of 0.1 μm, the D50 of 0.5 μm and the D50 of 3 μm is 0.02, and a homogenizer is used for dispersion to obtain a uniformly dispersed slurry;

[0079] (2) Spherical silica with a D50 of 6 μm and a particle size of 0 to 25 μm and spherical silica with a D50 of 26 μm and a particle size of 0 to 100 μm are added to the slurry obtained in step (1), mixed evenly and dried using a vibration dryer to obtain low thixotropic and high fluidity spherical silica, wherein the mass ratio of the total mass of the spherical silica with a D50 of 0.1 μm, 0.5 μm and 3 μm to the mass ratio of the spherical silica with a D50 of 6 μm and the spherical silica with a D50 of 26 μm is 50:20:30.

[0080] Example 7

[0081] A spherical silica with low thixotropy and high fluidity, wherein D50 is 16.4 μm, the mass percentage of spherical silica with a particle size of less than 5 μm is 17%, the mass percentage of spherical silica with a particle size of 5 μm≤≤10 μm is 33%, and the mass percentage of spherical silica with a particle size of 10 μm<<100 μm is 50%;

[0082] The preparation method of the low thixotropic and high fluidity spherical silica is as follows: (1) KH560 coupling agent and anhydrous ethanol are mixed uniformly in a mass ratio of 1:9 until clarified, and spherical silica with a D50 of 0.5 μm and a particle size of 0 to 10 μm and a D50 of 3 μm and a particle size of 0 to 10 μm are added, the mass ratio of the spherical silica with a D50 of 0.5 μm to the spherical silica with a D50 of 3 μm is 2:3, the total mass ratio of the mass of the coupling agent to the mass of the spherical silica with a D50 of 0.5 μm and the mass of the spherical silica with a D50 of 3 μm is 0.02, and a homogenizer is used for dispersion to obtain a uniformly dispersed slurry;

[0083] (2) Spherical silica with a D50 of 6 μm and a particle size of 0 to 25 μm and spherical silica with a D50 of 26 μm and a particle size of 0 to 100 μm are added to the slurry obtained in step (1), mixed evenly and dried using a vibration dryer to obtain low thixotropic and high fluidity spherical silica, wherein the mass ratio of the total mass of the spherical silica with a D50 of 0.5 μm and the spherical silica with a D50 of 3 μm to the mass ratio of the spherical silica with a D50 of 6 μm and the spherical silica with a D50 of 26 μm is 25:35:40.

[0084] Comparative Example 1

[0085] Spherical silica with a D50 of 0.5 μm and a particle size of 0 to 10 μm, spherical silica with a D50 of 6 μm and a particle size of 0 to 25 μm, and spherical silica with a D50 of 12 μm and a particle size of 0 to 100 μm are dry-mixed in a mass ratio of 38:36:26 to obtain powder, and a KH560 coupling agent is added for dry surface treatment (the mass ratio of the coupling agent to the powder is 0.02) to obtain spherical silica with a D50 of 4.5 μm.

[0086] Comparative Example 2

[0087] Spherical silica with a D50 of 0.5 μm and a particle size of 0 to 10 μm, spherical silica with a D50 of 3 μm and a particle size of 0 to 10 μm, spherical silica with a D50 of 6 μm and a particle size of 0 to 25 μm, and spherical silica with a D50 of 12 μm and a particle size of 0 to 100 μm are dry-mixed in the mass ratio in Example 7 to obtain powders, and a KH560 coupling agent is added for dry surface treatment (the mass ratio of the coupling agent to the powder is 0.02) to obtain spherical silica with a D50 of 18.3 μm.

[0088] Comparative Example 3

[0089] A spherical silica, wherein D50 is 24.3 μm, the mass percentage of spherical silica with a particle size of less than 5 μm is 10%, the mass percentage of spherical silica with a particle size of 5 μm ≤ ≤ 10 μm is 12%, and the mass percentage of spherical silica with a particle size of 10 μm < ≤ 100 μm is 78%;

[0090] The preparation method of the spherical silica is as follows: KH560 coupling agent and anhydrous ethanol are mixed uniformly in a mass ratio of 1:9 until the mixture is clarified, and spherical silica with a D50 of 0.5 μm and a particle size of 0 to 10 μm and a D50 of 3 μm and a particle size of 0 to 10 μm are added. The mass ratio of the spherical silica with a D50 of 0.5 μm to the spherical silica with a D50 of 3 μm is 2:3, and the mass ratio of the coupling agent to the spherical silica is 2:3. The total mass ratio of spherical silica with D50 of 0.5 μm and D50 of 3 μm is 0.02, and a homogenizer is used for dispersion to obtain a uniformly dispersed slurry; spherical silica with D50 of 6 μm and a particle size of 0 to 50 μm and spherical silica with D50 of 38 μm and a particle size of 0 to 150 μm are added to the slurry, mixed evenly, and then dried using a vibration dryer to obtain spherical silica with D50 of 24.3 μm.

[0091] Comparative Example 4

[0092] Spherical silica with a D50 of 0.5 μm and a particle size of 0 to 10 μm, spherical silica with a D50 of 6 μm and a particle size of 0 to 25 μm, and spherical silica with a D50 of 12 μm and a particle size of 0 to 100 μm are mixed in a ratio of 25:50:25, a KH560 coupling agent and anhydrous ethanol are mixed in a mass ratio of 3:7 until clarified, and the mixed powder is added, wherein the mass ratio of the coupling agent to the spherical silica is 0.02, and a homogenizer is used for dispersion to obtain a uniformly dispersed slurry; and a vibration dryer is used for drying to obtain spherical silica with a D50 of 4.0 μm, the mass percentage of spherical silica with a particle size of less than 5 μm is 37%, and the mass percentage of spherical silica with a particle size of 10 μm<particle size<100 μm is 25%.

[0093] The spherical silica products in Examples 1 to 7 and Comparative Examples 1 to 4 were mixed with bisphenol F epoxy resin (the mass ratio of the spherical silica product to the bisphenol F epoxy resin was 0.85), dispersed using a planetary ball mill, and then subjected to a constant temperature variable shear test using a rheometer to obtain the corresponding rheological curves, and the corresponding 10s -1 and 100s -1 Viscosity value A 10 -1, A 100 -1, and its thixotropy (A 10 -1 / A 100 -1), the results are shown in Table 1.

[0094] Use a 10mL disposable syringe to draw 1mL of the uniformly dispersed spherical silica and bisphenol F epoxy resin composition, and extrude it vertically onto the surface of a smooth glass slide cleaned with ethanol and kept at a constant temperature of 25°C. Record the flow diameter of the composition after 1 minute to determine the powder fluidity.

[0095] The cumulative 50% particle size (D50) on a volume basis was measured using laser diffraction scattering particle size distribution.

[0096] Table 1 Particle size distribution of spherical silica products in Examples 1 to 7 and Comparative Examples 1 to 4, thixotropy and flow diameter of spherical silica products in Examples 1 to 7 and Comparative Examples 1 to 4 after mixing with bisphenol F epoxy resin

[0097]

[0098] As can be seen from Table 1, the spherical silica provided by the present invention has low thixotropy and high fluidity. Under the condition of equivalent particle size, as the content of coupling agent increases, thixotropy increases and fluidity increases. Therefore, when D50=3-4μm, Example 2 has better effect; under the condition of equivalent D50, as the content of powder <5μm increases, thixotropy increases and fluidity decreases. Compared with Example 6, Example 5 has better effect; under the condition of equivalent D50, compared with dry modification, the thixotropy of wet modified product decreases and fluidity increases. Compared with Comparative Example 2, Example 7 has better effect; from Comparative Example 3, it can be seen that when the D50 and particle size distribution of spherical silica are not within the scope of the present invention, its fluidity deteriorates and thixotropy increases; from Comparative Example 4, it can be seen that firstly modifying the small-particle spherical silica can improve the fluidity of the product and reduce thixotropy.

[0099] 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 principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A spherical silica with low thixotropy and high fluidity, prepared from a coupling agent, spherical silica and a solvent; the D50 of the spherical silica with low thixotropy and high fluidity is 2-20 μm, the mass percentage of spherical silica with a particle size of less than 5 μm in the spherical silica with low thixotropy and high fluidity is 15-70%, the mass percentage of spherical silica with a particle size of 5 μm≤≤10 μm is 10-36%, and the mass percentage of spherical silica with a particle size of 10 μm<<100 μm is 10-50%.

2. The low thixotropic, high fluidity spherical silica according to claim 1, characterized in that: The spherical silica includes a first spherical silica, a second spherical silica and a third spherical silica.

3. The low thixotropic, high fluidity spherical silica according to claim 2, characterized in that: The particle size of the first spherical silica is 0-10 μm, and D50 is 0.1-3 μm.

4. The low thixotropic, high fluidity spherical silica according to claim 2, characterized in that: The particle size of the second spherical silica is 0 to 25 μm, and D50 is 5 to 8 μm.

5. The low thixotropic, high fluidity spherical silica according to claim 2, characterized in that: The particle size of the third spherical silicon dioxide is 0 to 100 μm, and D50 is 9 to 30 μm.

6. The method for preparing the low thixotropic and high fluidity spherical silica according to any one of claims 1 to 5, comprising: The coupling agent, the solvent and the spherical silica are mixed to obtain the spherical silica with low thixotropy and high fluidity.

7. The preparation method according to claim 6, characterized in that: The method for preparing the low thixotropic and high fluidity spherical silica comprises the following steps: (1) mixing a first spherical silica with a coupling agent and a solvent to obtain a coupling agent-modified first spherical silica slurry; (2) The coupling agent-modified first spherical silica slurry obtained in step (1) is mixed with the second spherical silica and the third spherical silica to obtain spherical silica with low thixotropy and high fluidity.

8. The preparation method according to claim 7, characterized in that: In the step (1), the mass ratio of the coupling agent to the first spherical silica is 0.005 to 0.

05.

9. The preparation method according to claim 7, characterized in that: The mass ratio of the first spherical silica in step (1), the second spherical silica and the third spherical silica in step (2) is (15-70): (10-50): (10-50).

10. Use of the low thixotropic, high fluidity spherical silica according to any one of claims 1 to 5 or the low thixotropic, high fluidity spherical silica prepared by the preparation method according to any one of claims 6 to 9 in liquid epoxy encapsulants.

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