Process for manufacturing a surface-treated compacted material processable on a single screw plastics conversion equipment

A surface-treated compacted material in the form of non-uniform and loosely compacted conglomerates of singularized coated particles having a mean particle size of 10 μm to 100 mm, wherein the surface-treated compacted material is obtained by a process comprising the following steps:

• a) providing at least one primary inorganic powder material at a temperature of between 20° C. and 300° C., wherein the at least one primary inorganic powder material is calcium carbonate that is optionally treated with a fatty acid;
• b) providing at least one molten surface treatment polymer selected from the group consisting of an ethylene copolymer, an ethylene-1-octene copolymer, a metallocene based polypropylene, a polypropylene homopolymer, and an amorphous polypropylene homopolymer;
• c) simultaneously or subsequently feeding the at least one primary inorganic powder material from step a) and the at least one molten surface treatment polymer from step b), and optionally at least one surface treatment agent, into a single screw high speed mixer;
• d) mixing the at least one primary inorganic powder material and the at least one molten surface treatment polymer in the single screw high speed mixer at 400 to 4000 rpm so that the surface treatment polymer forms layers around and totally coats singularized particles of the primary inorganic powder material;
• e) optionally transferring the coated particles of the primary inorganic powder material obtained in step d) to a second single screw high speed mixer and mixing the same;
• and
• f) cooling the coated particles of the primary inorganic powder material obtained from step d) or e) to directly obtain a surface-treated compacted material in the form of non-uniform and loosely compacted conglomerates of the singularized coated particles, wherein the non-uniform conglomerates have a mean particle size of 10 μm to 100 mm, and wherein the surface-treated compacted material (i) comprises 5 to 25 wt % of the surface treatment polymer and 75 to 95 wt % of the at least one primary inorganic powder, (ii) has a screen residue of more than 80 wt. % on a 45 μm screen, and (iii) is free flowing according to DIN-53492.