Producing cardboard with smooth, printable surface, especially for forming packaging cartons, including successive calendering in long and hard roller gaps between dewatering and coating

摘要

In the production of cardboard with a printable surface by forming a base sheet from a water-containing composition, removing water from the sheet by pressing followed by heating, calendering in roller gap(s) to smooth the surface and coating at least one surfaces, the sheet is (a) calendered in long roller gap(s) after dewatering by pressing and before applying the first coating layer and (b) calendered in hard roller gap(s) after calendered in long roller gap(s) and before applying the first coating layer. An independent claim is included for apparatus for producing cardboard, comprising a region for producing a water-containing fibrous sheet, pressing and heating regions for removing water, at least one calender roll gap and at least one coating station, where at least two calender roll gaps are positioned between the pressing region and the first coating station, the first roll gap being longer and the second being harder.