Microencapsulation of red phosphorus
AssigneeBayer Aktiengesellschaft
InventorsHenricus Peerlings, Michael Wagner, Wolfgang Podszun
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Abstract
A method for microencapsulating red phosphorus in polymerized urea resorcinol formaldehyde resin is disclosed. The method entails (i) preparing an aqueous mixture containing urea, resorcinol and formaldehyde, (ii) adding hexamethylene tetramine and optionally water to the mixture to yield a stabilized mixture (iii) dispersing red phosphorus in the to the stabilized mixture (iv) adding acid to the reaction mixture, and (v) collecting the resulting encapsulated red phosphorus. The product is suitable as flame retarding agent in molding compositions.
Claims15
A method for microencapsulating red phosphorus in polymerized urea resorcinol formaldehyde resin, comprising
- (i) preparing a mixture containing
- a) 0.4 to 4 wt. % urea,
- b) 2 to 20 wt. % resorcinol and
- c) 5 to 150 wt. % formaldehyde,
- (ii) adding to the mixture 0.1 to 8 wt. % hexamethylene tetramine in an aqueous phase to yield a stabilized mixture,
- (iii) dispersing red phosphorus in the to the stabilized mixture to yield a reaction mixture wherein weight ratio of red phosphorus to water is 1:0.3 to 1:3, and
- (iv) adding acid to the reaction mixture to reach a pH of 0 to 5, while maintaining the temperature of the reaction mixture at 25 to 150° C., and
- (v) collecting red phosphorus that is encapsulated in a shell of polymerized urea resorcinol formaldehyde resin,
- said wt. % being relative to the weight said red phosphorus.
Dependencies are inferred from the claim text.