Spherical silica powder

Patent metadata

Field	Value
Publication number	US-12091528-B2
Application number	US-202017436013-A
Country	US
Kind code	B2
Filing date	Jan 30, 2020
Priority date	Mar 26, 2019
Publication date	Sep 17, 2024
Grant date	Sep 17, 2024

Abstract

A spherical silica powder with a low dielectric tangent, wherein after formulating the spherical silica powder in a resin and molding it into a sheet, in a dielectric tangent of the spherical silica powder calculated by using the following Formula (I) based on a dielectric tangent (tan δc) of the sheet which is measured under the conditions a frequency is 35-40 GHz with a resonator method, B/A is 0.70 or lower, wherein “A” represents a dielectric tangent (tan δf A ) of the spherical silica powder before a dielectric tangent reduction treatment and “B” represents a dielectric tangent (tan δf B ) of the spherical silica powder after a dielectric tangent reduction treatment; and a specific surface area of said spherical silica powder after a dielectric tangent reduction treatment is 1-30 m 2 /g.

First claim

The invention claimed is:

1. Spherical fused silica powder that has been subjected to a dielectric tangent reduction treatment comprising heat treating a raw material spherical fused silica powder having a specific surface area of 1-30 m 2 /g at a temperature of 500-1100° C. and for a predetermined time in which heating temperature (° C.)×heating time (h) is 1000-26400° C.·h, the spherical fused silica powder having:
a dielectric tangent ratio B/A of 0.70 or lower, wherein “A” represents a dielectric tangent (tan δf A ) of the spherical fused silica powder before the dielectric tangent reduction treatment and “B” represents a dielectric tangent (tan δf B ) of the spherical fused silica powder after the dielectric tangent reduction treatment, the dielectric tangent (tan δf A , tan δf B ) of the spherical fused silica powder before and after the dielectric tangent reduction treatment being measured with a resonator method at a frequency of 35-40 GHz, a temperature of 20° C., and a humidity of 60% RH after formulating the spherical fused silica powder in a resin and thereafter molding the formulation into a sheet, and being calculated from the following Formula (I):

log
⁡
(

tan
⁢
δ
⁢
c

)

=

Vf
·

log
⁡
(

tan
⁢
δ
⁢
f

)

+

(

1
-
Vf

)

·

log
⁡
(

tan
⁢
δ
⁢
r

)

Formula
⁢

(
I
)

wherein, in Formula (I), the symbols have the following meanings:
tan δc: dielectric tangent of the sheet;
Vf: a volume fraction of the spherical fused silica powder in the sheet;
tan δr: a dielectric tangent of a resin sheet without the spherical fused silica powder therein;

and a specific surface area of 1-30 m 2 /g.

2. The spherical fused silica powder of claim 1 , wherein the fused spherical silica powder has an average circularity of 0.85 or higher.

3. The spherical fused silica powder of claim 1 , wherein the fused spherical silica powder is surface treated with a surface treatment agent.

4. The spherical fused silica powder of claim 1 , wherein the spherical fused silica powder has a density of 1.8-2.4 g/cm 3 .

5. An article comprising the spherical fused silica powder of claim 1 and a moisture-proof bag storing the fused spherical silica powder, the moisture-proof bag having a permeability of 0.1 (g/m 2 ·24h) or lower under the condition of B (Temperature 40° C.−Relative humidity 90%) defined by JIS Z 0208-1976.

6. A resin sheet comprising the spherical fused silica powder of claim 1 .

7. A method for storing the spherical fused silica powder of claim 1 , comprising a step of storing the spherical fused silica powder in a moisture-proof bag with a permeability of 0.1 (g/m 2 ·24h) or lower under the condition of B (Temperature 40° C.−Relative humidity 90%) defined by JIS Z 0208-1976.

Assignees

• Denka Company Ltd

Inventors

• Okabe Takuto
• Fukazawa Motoharu

Classifications

• C01B33/181

  by a dry process · CPC title

• C08K3/36

  Silica · CPC title

• H01B3/12

  ceramics · CPC title

• C08K9/06

  with silicon-containing compounds · CPC title

• C01P2004/32

  Spheres · CPC title