Method for preparing spherical or angular powder filler, spherical or angular powder filler obtained therefrom, and use thereof

1. A method for preparing a spherical or angular powder filler, comprising the steps of:

S1, providing a spherical or angular siloxane comprising T units, wherein the T unit=R 1 SiO 3 —, and R 1 is a hydrogen atom or an organic group independently selected from C 1 -C 18 ;

S2, performing a heat treatment on the spherical or angular siloxane, the heat treatment temperature between 250° C. and the temperature of oxidative decomposition of organic groups, the heat treatment time is 30 min-24 h, so that silicon hydroxyl groups in the spherical or angular siloxane are condensed to obtain a condensed siloxane, wherein new isolated outer surface Si—OHs and internal cracked surface Si—OHs are produced due to the spatial geometric limitation of the condensed siloxane; and

S3, adding a treatment agent to treat the condensed siloxane to promote the condensation of silicon hydroxyl groups in the condensed siloxane to give a spherical or angular powder filler, the treatment agent comprising a silane coupling agent and/or disilazane, the weight percentage of the treatment agent being 0.5-50 wt %, and the quotient of the molecular weight of at least a portion of the silane coupling agent and/or the disilazane divided by its specific gravity at 25° C. being less than or equal to 210, wherein the silane coupling agent and/or disilazane enters the internal cracks of the powder due to its small molecule in order to promote the condensation of the internal cracked surface Si—OHs.

2. The method according to claim 1 , wherein the spherical or angular siloxane further comprises Q units, D units, and/or M units, wherein the Q unit=SiO 4 —, the D unit=R 2 R 3 SiO 2 —, the M unit=R 4 R 5 R 6 SiO 2 —, and each of R 2 , R 3 , R 4 , R 5 , R 6 is a hydrogen atom or a hydrocarbyl independently selected from C 1 -C 18 .

3. The method according to claim 1 , wherein the spherical or angular siloxane further comprises silicon dioxide particles.

4. The method according to claim 1 , wherein the heat treatment temperature of S2 is 250-320° C.

5. The method according to claim 1 , wherein the silane coupling agent is at least one agent selected from silane coupling agent (R 7 ) a (R 8 ) b Si(M) 4-a-b ,

wherein R 7 , R 8 each is a hydrogen atom, a hydrocarbyl independently selected from C 1 -C 18 , a hydrocarbyl independently selected from C 1 -C 18 replaced by functional groups,

wherein the functional group is at least one group selected from the group consisting of following organic functional groups: vinyl, allyl, styryl, epoxy group, aliphatic amino, aromatic amino, methacryloxypropyl, acryloxypropyl, ureidopropyl, chloropropyl, mercapto propyl, polysulfide, isocyanate propyl; and

wherein M is an alkoxy group of C 1 -C 18 or a halogen atom, a=0, 1, 2 or 3, b=0, 1, 2 or 3, and a+b=1, 2 or 3.

6. The method according to claim 1 , wherein the disilazane is at least one agent selected from disilazane (R 9 R 10 R 11 )SiNHSi(R 12 R 13 R 14 ), and

wherein R 9 , R 10 , R 11 , R 12 , R 13 , R 14 each is a hydrogen atom or a hydrocarbyl independently selected from C 1 -C 18 .

7. The method according to claim 1 , wherein the method further comprises removing coarse oversize particles above 1, 3, 5, 10, 20, 45, 55, or 75 m in the spherical or angular powder filler by dry or wet sieving or inertial classification.

8. The method according to claim 1 , wherein the spherical or angular powder filler has a particle size of 0.1-50 m, and

wherein the volatile moisture content of the spherical or angular powder filler at 200° C. is less than or equal to 3000 ppm.

9. The method according to claim 8 , wherein the spherical or angular powder filler is tightly packed in the resin to form a composite material.

10. The method according to claim 9 , wherein the composite material is suitable for semiconductor packaging material, circuit board and intermediate semi-finished product.