Fumed silica with modified surface activity

Patent metadata

Field	Value
Publication number	US-2023062574-A1
Application number	US-202117792471-A
Country	US
Kind code	A1
Filing date	Jan 7, 2021
Priority date	Jan 14, 2020
Publication date	Mar 2, 2023
Grant date	—

Abstract

Fumed silica powder, surface treated with a surface treatment agent selected from the group consisting of organosilanes, silazanes, acyclic polysiloxanes, cyclic polysiloxanes, and mixtures thereof, wherein the powder has:a) a number of silanol groups relative to BET surface area dSiOH of at least 0.85 SiOH/nm2, as determined by reaction with lithium aluminium hydride;b) a methanol wettability of more than 40% by volume of methanol in methanol-water mixture;c) a tamped density of not more than 200 g/L.

First claim

1 - 15 . (canceled)

16 . A fumed silica powder that has been surface treated with an agent selected from the group consisting of: organosilanes, silazanes, acyclic polysiloxanes, cyclic polysiloxanes, and mixtures thereof; wherein the fumed silica powder comprises:
a) a number of silanol groups relative to BET surface area d SiOH of at least 0.85 SiOH/nm 2 , as determined by reaction with lithium aluminium hydride; b) a methanol wettability of more than 40% by volume of methanol in a methanol-water mixture; c) a tamped density of not more than 200 g/L.

17 . The fumed silica powder of claim 16 , wherein the fumed silica powder comprises a BET surface area of 30-500 m 2 /g.

18 . The fumed silica powder of claim 16 , wherein the surface treatment agent is selected from the group consisting of: octyltrimethoxysilane, octyltriethoxysilane, hexadecyltrimethoxysilane, hexadecyltriethoxysilane, dimethyldichlorosilane, chloro trimethylsilane, octamethylcyclotetrasiloxane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, glycidyloxypropyltrimethoxysilane, glycidyloxypropyltriethoxysilane, aminopropyltriethoxysilane, hexamethyldisilazane, polydimethylsiloxanes, and mixtures thereof.

19 . The fumed silica powder of claim 16 , wherein the fumed silica powder comprises a numerical median particle size d 50 of less than 100 μm.

20 . The fumed silica powder of claim 16 , wherein the fumed silica powder comprises a carbon content of from 0.5% to 10% by weight.

21 . The fumed silica powder of claim 16 , wherein the fumed silica powder comprises a number of silicon atoms in the surface treatment agent relative to BET surface area d [Si] of at least 1.0 [Si atoms]/nm 2 .

22 . The fumed silica powder of claim 16 , wherein the silica has a cumulative pore volume of pores >4 nm determined by a mercury intrusion method according to DIN ISO 15901-1 of at least 8.0 cm 3 /g.

23 . The fumed silica powder of claim 16 , wherein the fumed silica powder comprises a bulk density d bulk of less than 0.20 g/mL as determined by a mercury intrusion method according to DIN ISO 15901-1 at 0.0031 MPa.

24 . The fumed silica powder of claim 16 , wherein the fumed silica powder comprises a skeletal density of d sk of at least 0.50 g/mL, as determined by a mercury intrusion method of DIN ISO 15901-1 at 417 MPa.

25 . The fumed silica powder of claim 16 , wherein the fumed silica powder comprises a porosity of at least 60% as determined by a mercury intrusion method according to DIN ISO 15901-1 P=(1−d bulk /d sk ).

26 . The fumed silica powder of claim 16 , wherein the ratio d [Si] /d SiOH is 0.5 to 10.

27 . The fumed silica powder of claim 17 , wherein the surface treatment agent is selected from the group consisting of: octyltrimethoxysilane, octyltriethoxysilane, hexadecyltrimethoxysilane, hexadecyltriethoxysilane, dimethyldichlorosilane, chloro trimethylsilane, octamethylcyclotetrasiloxane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, glycidyloxypropyltrimethoxysilane, glycidyloxypropyltriethoxysilane, aminopropyltriethoxysilane, hexamethyldisilazane, polydimethylsiloxanes, and mixtures thereof.

28 . The fumed silica powder of claim 27 , wherein the fumed silica powder comprises a numerical median particle size d 50 of less than 100 μm.

29 . The fumed silica powder of claim 27 , wherein the fumed silica powder comprises a carbon content of 0.5% to 10% by weight.

30 . The fumed silica powder of claim 29 , wherein the fumed silica powder comprises a number of silicon atoms in the surface treatment agent relative to BET surface area d [Si] of at least 1.0 [Si atoms]/nm 2 .

31 . The fumed silica powder of claim 29 , wherein the silica has a cumulative pore volume of pores >4 nm determined by mercury intrusion method according to DIN ISO 15901-1 of at least 8.0 cm 3 /g.

32 . The fumed silica powder of claim 29 , wherein the fumed silica powder comprises a bulk density d bulk of less than 0.20 g/mL as determined by the mercury intrusion method according to DIN ISO 15901-1 at 0.0031 MPa.

33 . A process for producing the fumed silica powder of claim 16 , comprising the following steps:
a) subjecting a hydrophilic silica powder with a tamped density of not more than 200 g/L to thermal treatment at a temperature of 300° C. to 1400° C.; b) surface treating the hydrophilic silica powder subjected to thermal treatment in step a) in the presence of a surface treatment agent selected from the group consisting of: organosilanes, silazanes, acyclic polysiloxanes, cyclic polysiloxanes, and mixtures thereof and water; c) optionally crushing or milling the silica after step a) and/or b).

34 . A composition comprising the fumed silica powder according of claim 16 .

35 . The composition of claim 34 , wherein the composition is used as a paint, a coating, a silicone, a pharmaceutical, a cosmetic, an adhesive, a sealant, or a toner.

Assignees

• Evonik Operations Gmbh

Inventors

• Menzel Frank
• Lazar Björn
• Gerharz-Kalte Bettina
• Lygin Alexander
• Giesseler Mareike
• Golchert Rainer
• Mühlig Nina
• Aul Wolfgang
• Renger Tobias

Classifications

• C01B33/18 Primary

  Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof (preparation of aerogels by dehydrating gels C01B33/158; treatment to enhance the pigmenting or filling properties C09C) · CPC title

• C01P2006/14

  Pore volume · CPC title

• C09C1/3081 Primary

  Treatment with organo-silicon compounds · CPC title

• C01P2006/10

  Solid density · CPC title

• C01B33/183

  by oxidation or hydrolysis in the vapour phase of silicon compounds such as halides, trichlorosilane, monosilane · CPC title