During the production of kraft paper with a four-roll three-nip 2640/500 paper machine at Baiyun Paper in Zhumadian,Henan,the company found that stripes would appear on the surface of the paper sheet,which had a negative impact on the visual quality of the finished paper.After comprehensively analyzing the visual patterns of the stripe defects and the factors in the whole process,it was found that the stripes were mainly longitudinal felt marks caused by indentation marks in the nip rolls under positive pressure during the operation of the paper machine.Therefore,the company optimized the design of the felt by adjusting the weight of the positive pressure felt from 1350 g/m2 to 1650 g/m2,adopting a multi-layer base fabric design with the original two-layer fabric adjusted to a three-layer fabric,and replacing four Ø0.2 mm weft yarns of the base fabric with a single Ø0.4 mm yarn to improve the rigidity of the felt.After adjustment,the rigidity of the felt was improved,porosity and compression resistance was advanced,thus ensuring the dehydration efficiency of the press section.Additionally,the proportion of the base fabric in the positive pressure felt was increased to"base fabric/felt layer=54.5/45.5"to resist indentation marks that may occur in the later stages of the paper machine's operation.After implementation of these improved techniques,the stripes occurred on the paper surface was effectively resolved.Furthermore,the felt's service life was extended to approximately 30 days while still meeting the actual production requirements.
维普
万方数据