Melamine preparation and stable dispersion of melamine in polyether polyols

Stable dispersion of melamine, as a flame retardant, in polyether polyols having a melamine content of 20 to 70% by weight, wherein said dispersion contains 0.1 to 5% by weight of urea, thiourea, biuret or urea or thiourea substituted by lower alkyl groups, and wherein the average particle size of the melamine is 0.01 to 0.1 mm and wherein 0 to 50% by weight based on the melamine component, of melamine, is optionally replaced by further fire retardants.

Process for the preparation of flame-resistant polyurethane foams by reaction of isocyanates, polyols, foaming agents, wherein the polyol used is a dispersion of melamine, as a flame retardant, in polyether polyols, said dispersion having a melamine content of 20 to 70% by weight and, wherein said dispersion contains 0.1 to 5% by weight of urea, thiourea, biuret or urea or thiourea substituted by lower alkyl groups, wherein the average particle size of the melamine is 0.01 to 0.1 mm and wherein 0 to 50% by weight based on the melamine component, of melamine, is optionally replaced by further fire retardants.

Method for the preparation of a stable dispersion of 20 to 70% by weight, based on the dispersion, of melamine, as a flame retardant, said melamine having an average particle size of 0.01 to 0.1 mm, in which 0 to 50% by weight, based on the melamine component, of melamine, is optionally replaced by further flame retardants, wherein 0.1 to 5% by weight, based on the dispersion, of urea, thiourea, biuret or urea or thiourea substituted by lower alkyl groups is added to the dispersion for use as a stabilizer of the dispersion.