New coating concepts and their potential for efficient production

摘要

Increasing costs for raw materials and overcapacities put increasing pressure on the producers of coated paper.In this difficult economic situation it is necessary to develop more efficient machine concepts in order to secure the future.The major part of the worldwide production of coated paper is in the basis weight range between 70 and 150 g/m2.Blade coating or film/blade combinations are the dominating concepts for these grades.During the last years,new and alternative coating concepts and techniques have been studied.The focus of this development work was the replacement of a blade coat by a more efficient coating principle.The goal is to produce standard quality with lower investment costs and a higher efficiency. One of the two most important alternative concepts is double filmcoating.This is a combination of two film coaters for precoat and for topcoat,replacing a blade coat for medium basis weights.The potential of the double film concept will be compared to a state-of-the-art production line with film/blade coating.Based on actual data for productivity,the expected efficiency increase for double filmcoating will be determined.The quality level that can be achieved with two filmcoaters was investigated in several pilot trial series and will be discussed in detail.The second new coating principle is curtain coating.Since several years it is in the focus of the RD work in many companies.Meanwhile there are promising new fields of application besides the already proven specialty paper sector.Curtain Coating is an alternative particular/for high coat weights and for papers with highest demands for surface quality.Based on a case study for such a paper and new pilot trial results,the quality potential will be compared to state-of-the-art concepts.A general comparison of the most important paper grades and the typical coating concepts will show the areas where new concepts have the highest potential for improvement.