Contract n° BOS-088-UK
The motivation for increasing the filler content of woodfree paper lies in the raw material cost savings that can be achieved in this way. The detrimental effects of filler in paper have been identified and quantified for a woodfree offset paper. Strength losses and printing dust were found to be the most critical detrimental effects of high filler addition. Solutions to these problems were sought in three broad areas of papermaking technology — raw material selection and processing, chemical strength resins and post production treatment.
Production trials indicated that the solutions showing the greatest practical benefit were (a) increasing the mean fibre length by the use of additional softwood pulp, (b) optimised size press operation using high solids/low viscosity starch solutions and pigmented size press applications.
A final trial on a production machine clearly showed that functional woodfree offset paper could be produced with a filler content of nearly 40%.
KeywordsFiller Content Strength Loss Production Machine Production Trial Surface Smoothness
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