Stabilisieren von Polyacetalen

摘要

High molecular weight polyacetals are stabilized against thermal degradation and oxidation by using a stabilizer having the general formula A-CO-NH-CH2-B, where A is a hydroxyphenyl radical linked to the carbonyl group, preferably in the ortho-position, and B is an alkylated hydroxy phenyl radical, the hydroxyl group preferably being ortho- or parato the methylene group. The polyacetals contain the following structural unit in which R1 is a hydrogen atom and R2 is a hydrogen atom or an alkyl group; especially important are polyoxymethylenes in which R2 is a hydrogen atom. The polyoxymethylenes may be formed, for example, by polymerizing formaldehyde, or copolymers of formaldehyde or trioxane with, for example, diethylene glycol formal or ethylene oxide may used. The stabilizers of the invention, which are generally used in an amount of 0.5 to 2% by weight of the polymer, may be used in conjunction with other thermo-stabilizers, examples of which are given. In the examples, acetylated homo- and co-polymers of trioxane and ethylene oxide are stabilized with (a) 2-methyl-4-hydroxy-5-isopropyl -benzyl-salicylamide; (b) N-(2-methyl -4 - hydroxy - 5 - isopropyl - benzyl) - salicylamide; (c) with and without dicyan diamide, and (g) with and without dicyan diamide.