Catalyst for synthesis of siloxanes
View Patent ↗Compositions and methods for the production of siloxane materials using an azaphosphatrane as a catalyst. In one embodiment, there is provided a process for the ring opening polymerization of a cyclosiloxane in the presence of an azaphosphatrane. In another embodiment, there is provided a composition and method for condensation curing of a moisture curable composition using an azaphosphatrane.
1. A process for the synthesis of a siloxane polymer by ring opening polymerization of a cyclosiloxane comprising contacting a cyclosiloxane with an azaphosphatrane.
2. The process of claim 1 , wherein the azaphosphatrane is of the formula:
where R 9 , R 10 , R 11 and are independently chosen from hydrogen, a linear or branched alkyl comprising 1 to 10 carbon atoms, and an aromatic group comprising 6 to 12 carbon atoms, and a substituted phosphorous group with or without nitrogen; and A is chosen from hydrogen, R 12 , or (R 13 R 14 P—N=)t, where R 12 , R 13 , and R 14 are independently chosen from hydrogen, a linear or branched alkyl comprising 1 to 10 carbon atoms, and an aromatic group comprising 6 to 12 carbon atoms; and t is 1 to 10.
3. The process of claim 2 , wherein the azaphosphatrane is chosen from a compound of the formulas:
wherein A is hydrogen;
or a combination of two or more thereof.
4. The process of claim 1 , comprising an azaphosphatrane compound of the formula:
where R 9 , R 10 , and R 11 are independently chosen from methyl, isopropyl, or isobutyl.
5. The process of claim 1 , wherein the azaphosphatrane is present in an amount of from about 0.025 weight percent to about 5 weight percent based on the total weight of the cyclosiloxane.
6. The process of claim 1 , wherein the azaphosphatrane is present in an amount of from about 0.1 weight percent to about 0.4 weight percent based on the total weight of the cyclosiloxane.
7. The process of claim 1 , wherein the cyclosiloxane is of the formula (R 15 R 16 SiO) n , wherein R 15 and R 16 are independently chosen from hydrogen or an optionally substituted alkyl, alkenyl, aryl, alkaryl or aralkyl group having up to 8 carbon atoms, n denotes an integer with a value of from 3 to 12.
8. The process of claim 1 , wherein the cyclosiloxene is chosen from octamethyl cyclotetrasiloxane (D4), hexamethylcyclotrisiloxane (D3), octaphenylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane, hexamethyl-1,1-diphenylcyclotetrasiloxane, decamethyl pentacyclosiloxane, cyclopenta (methylvinyl) siloxane, cyclotetra(phenylmethyl) siloxane, cyclopenta methylhydrosiloxane, or a combination of two or more thereof.
9. The process of claim 1 comprising two or more cyclosiloxanes, along with silanol or methyl terminated poly(dimethylsiloxane) where at least two cyclosiloxanes have a different ring size from each other.
10. The process of claim 1 , wherein the process comprises adding an endblocker material.
11. The process of claim 10 , wherein the endblocker material is chosen from hexamethyl di siloxane; octamethyltrisiloxane; decamethyltetrasiloxane; dodecamethylpentasiloxane; tetradecamethylhexasiloxane; hexadecamethylheptasiloxane, or a combination of two or more thereof.
12. The process of claim 1 further comprising deactivating the catalyst.
13. The process of claim 12 , wherein deactivating the catalyst comprises: heating the product of the process at a temperature of about 100° C. or greater after the reaction; treating the product with water; bubbling carbon dioxide through the product; treating the product with a material to neutralize the catalyst, or a combination of two or more thereof.
14. The process of claim 12 further comprising filtering the reaction mixture.
15. The process of claim 14 further comprising treating the filtered reaction mixture with charcoal.