PREPARATION METHOD FOR SPHERICAL SILICA POWDER FILLER, POWDER FILLER OBTAINED THEREBY AND USE THEREOF

Abstract

A preparation method for a spherical silica powder filler, comprises the following steps: S1, providing spherical polysiloxane comprising T units by means of a hydrolysis condensation reaction of R.sub.1SiX.sub.3, wherein R.sub.1 is hydrogen atom or an independently selectable organic group having 1 to 18 carbon atoms, X is a hydrolyzable group, and the T unit is R.sub.1SiO.sub.3—; and S2, calcining the spherical polysiloxane under the condition of a dry oxidizing gas atmosphere at a calcining temperature between 850° C. and 1200° C., so as to obtain a spherical silica powder filler having a low hydroxyl content. The spherical silica powder filler is composed of at least one selected from Q.sub.1 unit, Q.sub.2 unit, Q.sub.3 unit and Q.sub.4 unit, wherein Q.sub.1 unit is Si(OH).sub.3O—, Q.sub.2 unit is Si(OH).sub.2O.sub.2—,Q.sub.3 unit is SiOHO.sub.3—, Q.sub.4 unit is SiO.sub.4—, and the content of Q.sub.4 unit is greater than or equal to 95%.

Claims

1. A preparation method for a spherical silica powder filler, comprising: S1, providing spherical polysiloxane comprising T units by means of a hydrolysis condensation reaction of R.sub.1SiX.sub.3, wherein Ri is hydrogen atom or an independently selectable organic group having 1 to 18 carbon atoms, X is a hydrolyzable group, and the T unit is R.sub.1SiO.sub.3—; and S2, calcining the spherical polysiloxane under a condition of a dry oxidizing gas atmosphere at a calcining temperature between 850° C. and 1200° C., so as to obtain a spherical silica powder filler having a low hydroxyl content, wherein the spherical silica powder filler is composed of at least one selected from Qi unit, Q.sub.2 unit, Q.sub.3 unit and Q.sub.4 unit, wherein Qi unit is Si(OH).sub.3O—, Q.sub.2 unit is Si(OH).sub.2O.sub.2—,Q.sub.3 unit is SiOHO.sub.3—, Q.sub.4 unit is SiO.sub.4—, and the content of Q.sub.4 unit is greater than or equal to 95%.

2. The preparation method according to claim 1, wherein the hydrolyzable group is an alkoxy group or a halogen atom.

3. The preparation method according to claim 1, wherein the oxidizing gas contains oxygen to oxidize all the organics in the polysiloxane.

4. The preparation method according to claim 1, wherein the calcination of the spherical polysiloxane is achieved by electric heating or indirect heating with combustion gas.

5. The preparation method according to claim 1, wherein the calcining temperature is between 850° C. and 1100° C.,and the calcining time is between 6 hours and 12 hours.

6. The preparation method according to claim 1, wherein the spherical polysiloxane further comprises a Q unit, a D unit, and/or a M unit, wherein Q unit is SiO.sub.4—, D unit is R.sub.2R.sub.3SiO.sub.2—, M unit is R.sub.4R.sub.5R.sub.6SiO—, wherein each of R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6 is a hydrogen atom or an independently selectable hydrocarbon group having 1 to 18 carbon atoms.

7. The preparation method according to claim 1, wherein the preparation method further comprises adding a treatment agent to perform surface treatment on the spherical silica powder filler, and the treatment agent comprises a silane coupling agent and/or disilazane; the silane coupling agent is (R.sub.7).sub.a(R.sub.8).sub.bSi(M).sub.4-a-b, wherein each of R.sub.7, Rs is a hydrogen atom, an independently selectable hydrocarbon group having 1 to 18 carbon atoms, or an independently selectable hydrocarbon group having 1 to 18 carbon atoms replaced by a functional group, wherein the functional group is selected from at least one of the following organic functional groups: vinyl, allyl, styryl, epoxy group, aliphatic amino, aromatic amino, methacryloxypropyl, acryloyloxypropyl, ureidopropyl, chloropropyl, mercaptopropyl, polysulfide group, isocyanate propyl; M is an alkoxy group with 1 to 18 carbon atoms or a halogen atom, a is 0, 1, 2 or 3, b is 0, 1, 2 or 3, a+b is 1, 2 or 3; and the disilazane is (R.sub.9R.sub.10R.sub.11)SiNHSi(R.sub.12R.sub.13R.sub.14), wherein each of R.sub.9, R.sub.10, R.sub.11, R.sub.12, R.sub.13, R.sub.14 is a hydrogen atom or an independently selectable hydrocarbon group having 1 to 18 carbon atoms.

8. The preparation method according to claim 1, wherein the spherical silica powder filler has a low hydroxyl content, and an average particle size of the spherical silica powder filler is between 0.1 .Math.m and 5 .Math.m.

9. The preparation method according to claim 8, wherein the spherical silica powder filler of different particle sizes is tightly packed and graded in resin to form a composite material, which is suitable for circuit board material and semiconductor packaging material.

10. The preparation method according to claim 9, wherein coarse particles above 1 .Math.m, 3 .Math.m, 5 .Math.m, 10 .Math.m, or 20 .Math.m in the spherical silica powder filler are removed by a dry or wet sieving or inertial classification.

11. The preparation method according to claim 2, wherein the spherical silica powder filler has a low hydroxyl content, and an average particle size of the spherical silica powder filler is between 0.1 .Math.m and 5 .Math.m.

12. The preparation method according to claim 3, wherein the spherical silica powder filler has a low hydroxyl content, and an average particle size of the spherical silica powder filler is between 0.1 .Math.m and 5 .Math.m.

13. The preparation method according to claim 4, wherein the spherical silica powder filler has a low hydroxyl content, and an average particle size of the spherical silica powder filler is between 0.1 .Math.m and 5 .Math.m.

14. The preparation method according to claim 5, wherein the spherical silica powder filler has a low hydroxyl content, and an average particle size of the spherical silica powder filler is between 0.1 .Math.m and 5 .Math.m.

15. The preparation method according to claim 6, wherein the spherical silica powder filler has a low hydroxyl content, and an average particle size of the spherical silica powder filler is between 0.1 .Math.m and 5 .Math.m.

16. The preparation method according to claim 7, wherein the spherical silica powder filler has a low hydroxyl content, and an average particle size of the spherical silica powder filler is between 0.1 .Math.m and 5 .Math.m.

Description

DESCRIPTION OF THE ENABLING EMBODIMENT

[0016] The preferred embodiments of the present invention are given below and described in detail.

[0017] The detection methods involved in the following embodiments are listed as follows.

[0018] The average particle size is measured with HORIBA’s laser particle size distribution analyzer LA-700.

[0019] The contents of Q.sub.1 unit, Q.sub.2 unit, Q.sub.3 unit and Q.sub.4 unit of the spherical silica powder filler are analyzed by .sup.29Si solid-state NMR nuclear magnetic resonance spectroscopy and calculated based on the nuclear magnetic resonance absorption peak area of Q.sub.1 unit, Q.sub.2 unit, Q.sub.3 unit and Q.sub.4 unit. Q.sub.4 unit content (%) = (Q.sub.4 unit peak area / (Qi unit peak area+Q.sub.2 unit peak area+Q.sub.3 unit peak area+Q.sub.4 unit peak area)) × 100.

[0020] The dielectric loss test method comprises: mixing different volume fractions of sample powders and paraffin to make test samples, and using a commercially available high-frequency dielectric loss meter to measure the dielectric loss under the condition of 10 GHz. Then the dielectric loss of the sample is obtained from the slope in the coordinate, wherein the ordinate represents the dielectric loss, and the abscissa represents the volume fraction. The dielectric losses of the Examples and Comparative Examples of the present invention at least can be relatively compared although it is generally difficult to obtain the absolute value of the dielectric loss.

[0021] In this text, “degrees” refers to Celsius degrees, i.e., °C.

[0022] In this text, the average particle size refers to the volume average diameter of the particles.

Embodiment 1

[0023] Deionized water of a certain weight at room temperature was added into a reactor with a stirrer. While stirring, methyltrimethoxysilane of 80 by weight was added and a small amount of acetic acid was added to adjust the pH to about 5. After the methyltrimethoxysilane was dissolved, 5% ammonia water of 25 by weight was added and stirred for 10 seconds, and then the stirring was stopped. After standing for 1 hour, it was filtered and dried to obtain spherical polysiloxane. The polysiloxane powder was put into a muffle furnace and dry air was introduced for calcination. The final calcining temperature was 850 degrees, 1000 degrees or 1100 degrees, and the calcining time was 12 hours. The analysis results of the samples were listed in following Table 1.

TABLE-US-00001 Deionized Water by Weight Average Particle Size (.Math.m) Final Calcining Temperature (°C.) Q.sub.4 Unit Content (%) Dielectric Loss (10 GHz) Example 1 1500 0.8 1000 >99 0.00005 Example 2 1100 1.2 1100 >99 0.00003 Example 3 800 3.0 850 96.0 0.00008 Example 4 600 4.5 1100 >99 0.00002 Comparative Example 1 800 3.0 750 94.5 0.0010

Embodiment 2

[0024] Deionized water of 1100 by weight at room temperature was added into a reactor with a stirrer. While stirring, propyltrimethoxysilane of 80 by weight was added and a small amount of acetic acid was added to adjust the pH to about 5. After the propyltrimethoxysilane was dissolved, 5% ammonia water of 25 by weight was added and stirred for 10 seconds, and then the stirring was stopped. After standing for 1 hour, it was filtered and dried to obtain spherical polysiloxane. The polysiloxane powder was put into a muffle furnace and dry air was introduced for calcination. The final calcining temperature was 950 degrees, and the calcining time was 6 hours. The analysis result of the sample was listed in following Table 2.

TABLE-US-00002 Average Particle Size (.Math.m) Final Calcining Temperature (°C.) Q.sub.4 Unit Content (%) Dielectric Loss (10 GHz) Example 5 0.6 950 97.0 0.00006

Embodiment 3

[0025] Deionized water of 2500 by weight at 40° C. was added into a reactor with a stirrer. While stirring, methyltrimethoxysilane of 80 by weight was added and a small amount of acetic acid was added to adjust the pH to about 5. After the methyltrimethoxysilane was dissolved, 5% ammonia water of 60 by weight was added and stirred for 10 seconds, and then the stirring was stopped. After standing for 1 hour, it was filtered and dried to obtain spherical polysiloxane. The polysiloxane powder was put into a muffle furnace and dry air was introduced for calcination. The final calcining temperature was 1000 degrees, and the calcining time was 12 hours. The heating method was changed to natural gas combustion (comparative example 2) with the direct combustion gas heating. The final calcining temperature was 1000 degrees, and the calcining time was 12 hours. The analysis results of the sample were listed in following Table 3. Obviously, the hydroxyl group in the silica was increase due to the moisture contained in the hot gas after natural gas combustion.

TABLE-US-00003 Average Particle Size (.Math.m) Final Calcining Temperature (°C.) Q.sub.4 Unit Content (%) Dielectric Loss (10 GHz) Example 6 0.15 1000 95.0 0.00009 Comparative Example 2 0.15 1000 92.5 0.0019

Embodiment 4

[0026] The crushed silica with an average particle size of 2 .Math.m was sent to a spheroidizing furnace with a flame temperature of 2500 degrees for melting and spheroidizing. All the spheroidized powders were collected as sample of Comparative Example 3. The analysis result of the sample was listed in following Table 4.

TABLE-US-00004 Average Particle Size (.Math.m) Q.sub.4 Unit Content (%) Dielectric Loss (10 GHz) Comparative Example 3 3.0 93.0 0.0014

[0027] It should be understood that the samples obtained in the Examples 1-6 may be surface-treated. Specifically, vinyl silane coupling agent, epoxy silane coupling, disilazane, etc. can be used to treat the samples as required. Also, at least two treatment agents can be used to treat the samples as required.

[0028] It should be understood that coarse particles above 1 .Math.m, 3 .Math.m, 5 .Math.m, 10 .Math.m, or 20 .Math.m in the spherical silica powder filler are removed by a dry or wet sieving or inertial classification.

[0029] It should be understood that the spherical silica powder filler of different particle sizes is tightly packed and graded in resin to form a composite material.

[0030] The foregoing description refers to preferred embodiments of the present invention and is not intended to limit the scope of the present invention. Various changes can be made to the foregoing embodiments of the present invention. That is to say, all simple and equivalent changes and modifications made in accordance with the claims of the present invention and the content of the description fall into the protection scope of the patent of the present invention. What is not described in detail in the present invention is conventional technical content.