Change in Curl of Newsprint by Physical Treatments - Effects of roll diameter, storage time, winding methods, calendering and humidity on curl -

The effects of roll diameter, winding time, winding methods and relative humidity on curl In newsprints(46, 54 , and 54 SNC) are examined. The larger MD curl appears at smaller roll diameter, with the extension of winding time, and at the treat ment of soft nip calendering. The MD curl shows the back side curl at winding methods with top side as outer side(TSO), and the top side curl with top side as inner side(TSI). While the CD curl in newsprints( 46 , and 54 SNC) treated with calender is hardly influenced by the storage times, roll diameter, and winding methods. However the CD curl in newsprint(54 ) gradually increases to a two weeks, and then hold constant regardless of roll diameter and winding methods.. The CD curl shows always the top side curl regardless of winding methods. At high relative humidity, the CD curl largely reduces, but the MD curl is not nearly changed. Especially, the CD curl in news-prints(54 SNC) is little affected by the changes of relative humidity.