Mixture for use in a fused filament fabrication process

A process for the production of a three-dimensional green body by a fused filament fabrication process, comprising:

• heating a mixture (M) to a temperature (TM), and
• depositing the mixture (M) into a build chamber using a layer-based additive technique to form the three-dimensional green body, wherein the temperature of the build chamber is in the range of from 50° to 80° C.,
• wherein the mixture (M) comprises:
• (a) from 40 to 70% by volume of an inorganic powder (IP) based on the total volume of the mixture (M),
• (b) from 30 to 60% by volume based on the total volume of the mixlure (M) of a binder (B) consisting of
• (b1) from 70 to 96% by weight of at least one polyoxymethylene (POM) based on the total weight of the binder (B),
• (b2) from 2 to 15% by weight of at least one polyolefin (PO) based on the total weight of the binder (B),
• (b3) from 2 to 26% by weight of at least one further polymer (FP) based on the total weight of the binder (B), wherein the at least one further polymer (FP) is polytetrahydrofuran,
• said method further comprising, after the depositing, removing at least 95% by weight of component (b1), based on the total weight of component (b1), from the three-dimensional green body to form a three-dimensional brown body;
• wherein the removal is carried out by acidic treatment and at a temperature in the range from 20 to 180° C.;
• wherein the particle size of the inorganic powder (IP)) is from 0.1 to 80 μm.