Calcium carbonate for rotogravure printing medium

A rotogravure printing medium comprising:

• a) a substrate having a first side and a reverse side, and
• b) a coating layer being in contact with at least the first side of the substrate, wherein the coating layer consists of:
• i) >50.0 to 100.0 parts by weight of at least one natural source of calcium carbonate comprising particles consisting of calcium carbonate in an amount of >50.0 wt %, based on the total dry weight of the natural source of calcium carbonate, the at least one natural source of calcium carbonate comprises particles having a BET specific surface area of from 4.0 to 12.0 m2/g, measured by the BET nitrogen method, wherein the at least one natural source of calcium carbonate is in the form of crumbles comprising dolomite and/or at least one natural ground calcium carbonate (NGCC),
• ii) 0.0 to <50.0 parts by weight of at least one further pigment suitable for papermaking,
• iii) 3.0 to 6.0 parts by weight of at least one synthetic binder,
• iv) 0.1 to 0.5 parts by weight of at least one stearate salt,
• v) optionally 1.0 to 1.5 parts by weight of at least one polysaccharide,
• vi) optionally 0.1 to 0.5 parts by weight of at least one thickener, and
• vii) optionally 0.2 to 3.0 parts by weight of at least one dispersing agent,
• wherein the sum of the at least one natural source of calcium carbonate and the at least one further pigment in the coating layer is 100.0 parts by weight;
• wherein the crumbles are a material being composed of a plurality of particles comprising the at least one source of calcium carbonate and moisture, said crumbles obtained by a process comprising the following steps:
• a) providing at least one calcium carbonate-containing material in the form of an aqueous slurry having solids content in the range from 5.0 to 45.0 wt.-%, based on the total weight of the slurry,
• b) wet grinding the at least one calcium carbonate-containing material of step a) to obtain an aqueous slurry of at least one wet-ground calcium carbonate containing material, wherein the particles of the at least one wet-ground calcium carbonate-containing material have a
• i) weight particle size d75 of 0.7 to 3.0 μm,
• ii) weight median particle size d50 of 0.5 to 2.0 μm,
• iii) weight particle size d25 of 0.1 to 1.0 μm, as measured according to the sedimentation method, and
• iv) a BET specific surface area of from 4.0 to 12.0 m2/g, measured by the measured by nitrogen gas adsorption using the BET isotherm (ISO 9277:2010), and
• c) mechanical dewatering of the aqueous slurry of step b) to obtain crumbles comprising the at least one calcium carbonate-containing material having solids content of 78.0 wt.-% to 90.0 wt.-%, based on the total weight of the crumbles.