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Oegstgeest, Netherlands

Gerli A.,Global Graphic Customer Support Center | Eigenbrood L.C.,Global Graphic Customer Support Center | Nurmi S.,Global Graphic Customer Support Center
Tappi Journal | Year: 2011

Various uncoated woodfree papers produced on a pilot paper machine were characterized for picking resistance, using an IGT printability tester, and standard sheet properties. The papers were produced with and without surface sizing or a debonding agent, with different filler types (ground calcium carbonate [GCC] or precipitated calcium carbonate [PCC]) and levels (20% and 25%), and by varying the calendering conditions. The goal was to assess the relationship between surface strength of these sheets and their bulk strength properties, such as tensile strength and internal bond. Variables such as the use of a debonding agent or the application of surface size had equal effect on picking resistance and tensile strength. Increase of filler content in paper or replacement of GCC with PCC reduced picking resistance, tensile strength, and internal bond. Increase of the calendering load, for both GCC and PCC sheets, reduced picking resistance but left tensile strength and internal bond unaffected. Picking resistance of the 25% PCC-containing sheets was affected at a significantly larger extent by an increase in calendering load than picking resistance of the 25% GCC-containing sheets. These results point out that the surface of a highly filled PCC sheet is particularly sensitive to surface damage by calendering. Source


Gerli A.,Global Graphic Customer Support Center | Eigenbrood L.C.,Global Graphic Customer Support Center
Tappi Journal | Year: 2012

A novel method was developed for the determination of linting propensity of paper based on printing with an IGT printability tester and image analysis of the printed strips. On average, the total fraction of the surface removed as lint during printing is 0.01%-0.1%. This value is lower than those reported in most laboratory printing tests, and more representative of commercial offset printing applications. Newsprint paper produced on a roll! blade former machine was evaluated for linting propensity using the novel method and also printed on a commercial coldset offset press. Laboratory and commercial printing results matched well, showing that linting was higher for the bottom side of paper than for the top side, and that linting could be reduced on both sides by application of a dry-strength additive. In a second case study, varying wet-end conditions were used on a hybrid former machine to produce four paper reels, with the goal of matching the low linting propensity of the paper produced on a machine with gap former configuration. We found that the retention program, by improving fiber fines retention, substantially reduced the linting propensity of the paper produced on the hybrid former machine. The papers were also printed on a commercial coldset offset press. An excellent correlation was found between the total lint area removed from the bottom side of the paper samples during laboratory printing and lint collected on halftone areas of the first upper printing unit after 45000 copies. Finally, the method was applied to determine the linting propensity of highly filled supercalendered paper produced on a hybrid former machine. In this case, the linting propensity of the bottom side of paper correlated with its ash content. Source

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