Method for calendering surface sized paper/paperboard to improve smoothness

摘要

A calendering method which enhances the smoothness of surface sized paper/paperboard by a combination of temperature and moisture gradient calendering processes without the fiber sticking/picking problems that affect runnability and without using waterboxes. The moisture gradient calendering is performed so that the cross direction moisture profile can be corrected and high smoothness levels can be obtained. Heated calender rolls form a hot pressure nip having a temperature greater than the temperature of the moisturized web. Lubricant is applied to both sides of the web to prevent fiber sticking/picking in the hot nip. The lubricant may be applied by the size press, by the moisturizing showers or by separate lubricant showers. The smoothness developed by moisturizing and hot nip calendering is substantially irreversible.