Method for producing hydrophobic silica mouldings

Patent metadata

Field	Value
Publication number	US-11535727-B2
Application number	US-201716338196-A
Country	US
Kind code	B2
Filing date	Feb 27, 2017
Priority date	Feb 27, 2017
Publication date	Dec 27, 2022
Grant date	Dec 27, 2022

Abstract

The invention relates to a method for producing hydrophilic silicia moulded bodies, in which i) a mixture containing hydrophilic silicic acid is added at a maximum temperature of 55° C. to hydrophobic means and ii) the mixture obtained in step i) is compacted after a maximum storage time of 30 days to form moulded bodies, iii) during steps ii and iii and until the moulded bodies are used, the temperature is at a maximum of 55° C.

First claim

The invention claimed is:

1. A method for producing mechanically stable hydrophobic silica moldings, comprising:
i) coating a mixture containing hydrophilic silica with at least one hydrophobicizing agent at a temperature of not more than 55° C.; and
ii) compacting the mixture from step i) after a storage time of not more than 30 days, to create moldings,
iii) wherein the temperature is not more than 55° C. during steps i) and ii) and up to use of the moldings, and wherein the moldings produced in step ii) are mechanically stable moldings having a density of from 100 to 400 g/L.

2. The method of claim 1 , wherein the moldings are plates or mats.

3. The method of claim 1 , wherein the hydrophobicizing agents are reactive organosilanes, organosiloxanes or silicone resins having hydrophobicizing properties, which are liquid at 25° C. and are capable of reacting with Si—OH groups of the silica surface.

4. The method of claim 1 , wherein the hydrophobicizing agents are OH-terminated polydimethylsiloxanes having a kinematic viscosity measured at 25° C. of from 5 mm 2 /s to 100 mm 2 /s.

5. The method of claim 1 , wherein the hydrophilic silica is pyrogenic silica, precipitated silics or mixture thereof having a BET surface area in accordance with DIN 66131 in the range from 100 to 500 m 2 /g.

6. The method of claim 1 , wherein, in step i, the hydrophilic silica is coated with from 0.5% to 20% by weight of hydrophobicizing agent, based on the weight of the total mixture.

7. The method of claim 1 , wherein the mixture is stored for not more than 15 days after step i) and before the compaction in step ii).

8. The method of claim 1 , wherein the mixture from step i) is deaerated before compaction to a target density.

9. The method of claim 1 , wherein residues obtained in the method of claim 1 and/or during the use of moldings are recirculated into the method of claim 1 .

10. The method of claim 1 , wherein the hydrophobicizing agent in the mixture from step i) has not completely reacted with surface silanol groups of the silica prior to compaction in step ii).

11. The method of claim 1 , wherein the moldings are insulation boards.

12. The method of claim 1 , wherein the moldings are thermal insulators having a thermal conductivity of 18 to 35 mW/m·K.

13. The method of claim 1 , wherein prior to compacting in step ii), an IR opacifier, electrostatic charge—reducing agent, or both of these are added.

14. The method of claim 1 , wherein compacting in step ii) takes place within 24 hours of step i).

15. A method for producing hydrophobic silica moldings, comprising:
iv) coating a mixture containing hydrophilic silica with at least one hydrophobicizing agent at a temperature of not more than 55° C.; and
v) compacting the mixture from step i) after a storage time of not more than 30 days, to create moldings,
vi) wherein the temperature is not more than 55° C. during steps i) and ii) and up to use of the moldings,

further comprising adding fibers to the mixture before step ii).

16. The method of claim 15 , wherein the moldings produced in step ii) are mechanically stable moldings having a density of from 100 to 400 g/L.

17. The method of claim 15 , wherein the hydrophobicizing agent in the mixture from step i) has not completely reacted with surface silanol groups of the silica prior to compaction in step ii).

18. The method of claim 15 , wherein the moldings are insulation boards.

19. The method of claim 15 , wherein prior to compacting in step ii), an IR opacifier, electrostic charge—reducing agent, or both of these are added.

Assignees

• Wacker Chemie Ag

Inventors

• Hindelang Konrad
• Jantke Dominik
• Weidner Richard

Classifications

• C09C1/3081 Primary

  Treatment with organo-silicon compounds · CPC title

• C08K9/06 Primary

  with silicon-containing compounds · CPC title

• C04B2111/27

  Water resistance, i.e. waterproof or water-repellent materials · CPC title

• C01P2006/12

  Surface area · CPC title

• C09C3/12

  Treatment with organosilicon compounds {(C09C3/006 takes precedence)} · CPC title