Process for the preparation of flocculated filler particles

A process for the preparation of flocculated filler particles comprising:

• providing at least one first aqueous suspension S1 in a first vessel that comprises at least one flocculating additive A and at least one first filler material;
• providing at least one second aqueous suspension S2 in a second vessel that comprises at least one flocculating additive B and at least one second filler material, wherein the at least one flocculating additive B is different from the at least one flocculating additive A, wherein more than 99 wt.-% of the at least one first filler material in the first aqueous suspension S1 and the at least one second filler in the second aqueous suspension S2 are the same;
• and
• combining the at least one first aqueous suspension S1 with the at least one second aqueous suspension S2 simultaneously in a third vessel, under conditions effective to form a mixture, the mixture comprising an aqueous suspension SM of flocculated filler particles, wherein the aqueous suspension SM of flocculated filler particles fine fractions has a mono-modal particle size distribution, and wherein the content of the at least one flocculating additive A in the first aqueous suspension S1 is from 0.5 to 10 wt.-%, based on the total weight of the first aqueous suspension S1, and/or the content of the at least one flocculating additive B in the second aqueous suspension S2 is from 0.1 to 10 wt.-%, based on the total weight of the second aqueous suspension S2.