Method for the production of a colored polyoxymethylene copolymer

A method for the production of a colored polyoxymethylene copolymer comprising the following steps:

• a) providing a component (A1) and a component (A2), wherein
• component (A1) contains a raw polyoxymethylene copolymer in particulate form, comprising a polyoxymethylene copolymer and 2 to 30% by weight of unreacted residual monomers with regard to the total weight of the raw polyoxymethylene copolymer, and
• component (A2) contains a coloring agent in particulate form,
• b) simultaneously feeding components (A1) and (A2) to a degassing apparatus, in which the raw polyoxymethylene copolymer is melted and mixed with component (A2), and whereby the unreacted residual monomers are at least partially removed from the raw polyoxymethylene copolymer to obtain the colored polyoxymethylene copolymer,
• c) removing the colored polyoxymethylene copolymer from the degassing apparatus, wherein the degassing apparatus consists of a melting device, which consists of a melting zone, a degassing device, which consists of a first degassing zone, a second degassing zone and a third degassing zone, and wherein the degassing device is operated at a temperature of from 155 to 270° C. and a pressure of from 0.1 mbara to 10 bara,
• wherein the coloring agent is at least one black coloring agent selected from the group consisting of carbon black, activated carbon, carbon nanotubes, graphen black, black organic pigments and black organic dyes, and component (A2) is provided in form of a masterbatch.