Microencapsulated red phosphorus
AssigneeBayer Aktiengesellschaft
InventorsMichael Wagner, Wolfgang Podszun, Henricus Peerlings
Life of this patent
Estimating the term…
Abstract
A method for preparing encapsulated red phosphorus is disclosed. The method entails obtaining a material system that contains dispersed particulate red phosphorus having a mean particle size of 0.1 to 100 μm in an aqueous phase that comprise urea, formaldehyde and a water-soluble silicon dioxide precursor, adding to the material system a sufficient amount of acid to lower the pH to 0 to 5 and maintaining the resulting acidic system at a temperature of 80 to 120° C. for a period longer than one hour. The encapsulated red phosphorus of the invention is suitable for using as a flame retarding agent for plastics molding compositions.
Claims11
A material system comprising encapsulated red phosphorus having a core/shell structure wherein core contains red phosphorus in particulate form and wherein shell contains a combination of urea formaldehyde resin and silicon dioxide the combination produced in a one pot reaction, said urea formaldehyde resin being a water insoluble resin formed by the condensation of urea, formaldehyde, resorcinol and hexamethylenetetramine.
A method for preparing an encapsulated red phosphorus in a one pot reaction comprising
- (i) obtaining a material system that contains dispersed particulate red phosphorus having a mean particle size of 0.1 to 100 μm in an aqueous phase that comprise urea, formaldehyde and a water-soluble silicon dioxide precursor, said phase having a pH of 6 to 13, and
- (ii) adding to the material system a sufficient amount of acid to lower the pH to 0 to 5 and to obtains an acidic system,
- (iii) maintaining the acidic system at a temperature of 80 to 120° C. for a period longer than one hour.
Dependencies are inferred from the claim text.