PROCESS FOR THE PREPARATION OF AN OLIGOMER FLAME-RETARDING ADDITIVE AND ITS USE FOR ENDOWING A LINEAR POLYESTER WITH SELF-EXTINGUISHING CHARACTERISTICS

摘要

An oligomer flame-retarding additive can be defined by the general formula CHEM wherein: R is the hydrogen atom, or a linear or branched alkyl radical, containing from 1 to 6 carbon atoms; m takes the value 1, 2 or 3; n takes a value, or an average value, comprised within the range of from 2 to 50. Such an additive is obtained by means of the oligomerization of a hydroxyalkylenephenylphosphinic acid or of a related alkyl ester thereof. According to another form of practical embodiment, the flame-retarding additive is the product of co-oligomerization of a hydroxyalkylenephenylphosphinic acid, or of a related alkyl ester thereof, with a phenylphosphonic acid or a related alkyl ester thereof. Such oligomer additives are used for endowing a linear polyester with self-extinguishing characteristics.