Polyaryloxyphosphazene caustic wash
AssigneeEthyl Corporation
InventorJ. Robert Adams, Jr.
Life of this patent
Estimating the term…
Abstract
Phenolic impurities are removed from polyaryloxyphosphazenes by extracting a solution of the crude polyaryloxyphosphazene with an aqueous lower alcohol alkali metal base solution such as aqueous methanolic sodium hydroxide.
Claims12
A process for removing phenolic impurities from a crude polyphosphazene gum having aryloxy substituents and containing phenolic impurities said process comprising:
- (A) forming a solution of said polyphosphazene in a solvent for said crude polyphosphazene,
- (B) extracting said crude polyphosphazene solution at least once with an aqueous lower alcohol solution of an alkali metal base to extract said phenolic impurities into the aqueous lower alcohol phase,
- (C) separating the organic phase containing the extracted purified polyphosphazene from the aqueous lower alcohol phase and
- (D) recovering purified polyaryloxyphosphazene gum from said organic phase.
In a process for making a purified polyaryloxyphosphazene gum, said process comprising reacting a substantially linear high molecular weight polyphosphonitrilic chloride with a sodium aryloxide, said reacting being conducted in a solvent to form a solution of said polyaryloxyphosphazene gum containing aryl hydroxy impurities, the improvement comprising extracting said solution at least once with an aqueous lower-alcohol alkali metal hydroxide solution to remove a substantial portion of said arylhydroxy impurities.
Dependencies are inferred from the claim text.