Method for producing hydrophobic silica granules

Patent metadata

Field	Value
Publication number	US-11377564-B2
Application number	US-201716481863-A
Country	US
Kind code	B2
Filing date	Feb 27, 2017
Priority date	Feb 27, 2017
Publication date	Jul 5, 2022
Grant date	Jul 5, 2022

Abstract

Granular and/or shaped hydrophobic silica useful for thermal insulation materials are prepared by mixing hydrophilic silica with a hydrophobicizing agent at low temperature so the hydrophobicizing agent does not appreciably react, followed by deaeration and compaction.

First claim

The invention claimed is:

1. A process for producing hydrophobic silica granular insulation materials, comprising the following steps, in the order given:
i) coating a mixture consisting of hydrophilic silica, optionally one or more IR opacifiers, optionally one or more antistatic agents, and optionally one or more fillers other than hydrophilic silica, with a hydrophobing composition consisting of organosilicon compounds which eliminate not more than 1 wt. %, based on the weight of the hydrophobing composition, of volatile organic compounds, HCl, or ammonia, selected from the group consisting of organosilanes, organosiloxanes, silicone resins, and mixtures thereof,
ii) after not more than 24 hours, deaerating the mixture from step i),
iii) compacting the mixture from step ii) to a target bulk density, and
iv) granulating during the compaction in step iii),

wherein at least steps i) and ii) are conducted at temperatures of 55° C. or less.

2. The process of claim 1 , wherein the hydrophobing composition consists of a cyclic organosiloxane.

3. The process of claim 1 , wherein the hydrophobing composition consists of OH-terminated organopolysiloxanes.

4. The process of claim 1 , wherein at least steps i) and ii) are conducted at temperatures of 40° C. or less.

5. The process of claim 1 , further comprising:
v) screening granulate from step iv) to remove fines and recirculating the removed fines to step i).

6. The process of claim 5 , wherein all steps are conducted at temperatures of 40° C. or less.

7. The process of claim 1 , wherein following deaeration, the bulk density of the deaerated coated silica is >70 g/L.

8. The process of claim 1 , wherein the thermal conductivity of the granulates is ≤30 mW/m·K.

9. The process of claim 1 , wherein the coated silica obtained in step i) is a free-flowing powder.

Assignees

• Wacker Chemie Ag

Inventors

• Hindelang Konrad
• Jantke Dominik
• Weidner Richard

Classifications

• C01P2006/22

  Rheological behaviour as dispersion, e.g. viscosity, sedimentation stability · CPC title

• C09C3/12

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

• C01P2006/12

  Surface area · CPC title

• C04B30/00

  Compositions for artificial stone, not containing binders · CPC title

• 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