Method for the production of stable polyoxymethylene copolymers (cPOM)

A method for the production of a polymer molding composition (PM) comprising the steps:

• a1) polymerization of at least one main monomer selected from the group of cyclic formals, and at least one first comonomer selected from the group of those of the formula (II)
• where
• R1 to R4 are each, independently of one another, a hydrogen atom, a C1-C4-alkyl group or a alkoxy-substituted alkyl group having from 1 to 4 carbon atoms and R5 is a chemical bond, a —CH2—, —OCH2—, a C1-C4-alkyl- or C1-C4-alkoxy-substituted methylene group or a corresponding oxymethylene group and n is from 0 to 3, and optionally at least one second comonomer, in the presence of the acid catalyst, in order to provide the first mixture (M1) comprising the polyoxymethylene copolymer (cPOM) and the acid catalyst,
• b) adding triisopropanolamine to the first mixture (M1) to deactivate the acid catalyst in order to obtain a second mixture (M2) comprising the polyoxymethylene copolymer (cPOM) and a complex of the acid catalyst and triisopropanolamine, wherein the triisopropanolamine in step b) is added in a molar excess in view of the acid catalyst from 25:1 to 1:1,
• c) optionally adding at least one additive to the second mixture (M2).