Method for preparing precipitated silicas, novel precipitated silicas and their uses, in particular for strengthening polymers

Patent metadata

Field	Value
Publication number	US-9862810-B2
Application number	US-201314424368-A
Country	US
Kind code	B2
Filing date	Sep 2, 2013
Priority date	Aug 31, 2012
Publication date	Jan 9, 2018
Grant date	Jan 9, 2018

Abstract

The present disclosure relates to a novel process for the preparation of a precipitated silica, in which:
a silicate is reacted with at least one acidifying agent, so as to obtain a suspension of precipitated silica, said suspension of precipitated silica is filtered, so as to obtain a filtration cake, said filtration cake is subjected to a liquefaction operation comprising the addition of an aluminum compound, after the liquefaction operation, a drying stage is carried out, characterized in that methylglutaric acid is added to the filtration cake, during or after the liquefaction operation.

It also relates to novel precipitated silicas and to their uses.

First claim

The invention claimed is:

1. A precipitated silica having:
a BET specific surface area of between 45 and 550 m 2 /g,
a content (C) of polycarboxylic acid and corresponding carboxylate, expressed as total carbon, of at least 0.15% by weight, and
an aluminum (Al) content of at least 0.20% by weight,
wherein the polycarboxylic acid comprises methylglutaric acid.

2. The precipitated silica as claimed in claim 1 , wherein the BET specific surface area is between 100 and 240 m 2 /g.

3. The precipitated silica as claimed in claim 1 , wherein the content (C) of polycarboxylic acid and corresponding carboxylate, expressed as total carbon, is at least 0.25% by weight.

4. The precipitated silica as claimed in claim 1 , wherein the aluminum (Al) content is at least 0.30% by weight.

5. The precipitated silica as claimed in claim 1 , wherein the precipitated silica exhibits a dispersive component of the surface energy γ s d of less than 43 mJ/m 2 .

6. The precipitated silica as claimed in claim 1 , wherein the precipitated silica exhibits a dispersive component of the surface energy γ s d of at least 40 mJ/m 2 and of less than 43 mJ/m 2 .

7. The precipitated silica as claimed in claim 1 , wherein the precipitated silica exhibits a dispersive component of the surface energy γ s d of less than 40 mJ/m 2 .

8. The precipitated silica as claimed in claim 1 , wherein the precipitated silica exhibits a water uptake of greater than 6%.

9. A process for the preparation of the precipitated silica of claim 1 , the process comprising:
reacting at least one silicate with at least one acidifying agent, so as to obtain a suspension of precipitated silica,
filtering said suspension of precipitated silica, so as to obtain a filtration cake,
subjecting said filtration cake to a liquefaction operation comprising the addition of an aluminum compound
adding methylglutaric acid to the filtration cake, during or after the liquefaction operation, and
optionally drying the filtration cake after the liquefaction operation.

10. The process as claimed in claim 9 , wherein the aluminum compound is added to the filtration cake during the liquefaction operation prior to the addition of the methylglutaric acid.

11. The process as claimed in claim 9 , wherein the methylglutaric acid and the aluminum compound are simultaneously added to the filtration cake during the liquefaction operation.

12. The process as claimed in claim 9 , wherein the methylglutaric acid is added to the filtration cake after the liquefaction operation.

13. The process as claimed in claim 9 , wherein a portion or all of the methylglutaric acid is in the anhydride, ester, alkali metal salt (carboxylate) or ammonium salt (carboxylate) form.

14. The process as claimed in claim 9 , wherein the aluminum compound is an alkali metal aluminate.

15. The process as claimed in claim 9 , wherein reacting at least one silicate with at least one acidifying agent comprises:
(i) forming an initial vessel heel comprising at least a portion of the total amount of the silicate involved in the reaction and an electrolyte, the concentration of silicate in said initial vessel heel being less than 100 g/l,
(ii) adding the acidifying agent to said vessel heel until a value for the pH of the reaction medium of at least 7.0 is obtained, and
(iii) adding additional acidifying agent and, if appropriate, simultaneously adding the remaining amount of silicate to the reaction medium; and
adding methylglutaric acid to the filtration cake, either during the liquefaction operation, or after the liquefaction operation and before the drying stage.

16. A method for reducing the viscosity of a polymer composition, the method comprising adding a precipitated silica as claimed in claim 1 to said composition.

17. A polymer composition comprising a precipitated silica as claimed in claim 1 .

18. An article comprising at least one polymer composition as claimed in claim 17 , wherein the article is selected from the group consisting of a footwear sole, a floor covering, a gas barrier, a flame-retardant material, a roller for cableways, a seal for domestic electrical appliances, a seal for liquid or gas pipes, a braking system seal, a pipe, a sheathing, a cable, an engine support, a battery separator, a conveyor belt, a transmission belt or a tire.

Assignees

• Rhodia Operations

Inventors

• Boivin Cèdric
• Guy Laurent
• Perin Eric
• Lamiri Kilani

Classifications

• C08K3/36

  Silica · CPC title

• C08K3/22

  of metals · CPC title

• C01B33/128

  by acidic treatment of aqueous silicate solutions · CPC title

• C08K5/092 Primary

  Polycarboxylic acids · CPC title

• C01B33/193 Primary

  of aqueous solutions of silicates · CPC title