Method for the manufacture of a colored polymer composition

A method for the manufacture of a colored polymer composition comprising a polymer, a release agent and a colorant, the method comprising the steps of

• feeding a solid form of a release agent composition comprising said release agent and said colorant to a feed section of a melt mixing device, and
• separately feeding said polymer to said melt mixing device and mixing said release agent composition and said polymer in said melt mixing device at a temperature above the melting temperature of said polymer, wherein
• said colorant is a pigment, or a dye which is soluble in said release agent,
• said polymer composition comprises polycarbonate, and
• the release agent consists of penta-erythritol tetra stearate, glycerol monostearate, glycerol tristearate or a mixture thereof,
• wherein the composition does not comprise carbon based pigments,
• wherein the release agent composition comprises
• 60 to 99 wt. % of the release agent based on the weight of the release agent composition;
• 0.001 to 0.1 wt. % of the colorant based on the weight of the release agent composition;
• and
• 0 to 40 wt. % of a UV stabilizer based on the weight of the release agent composition;
• and
• wherein the polymer comprises 90 to 100 wt. % of a polycarbonate or a mixture of at least two aromatic polycarbonates based on the weight of the polymer.