Forming fabrics, drainage rates and paper properties

摘要

The effect of the structure of forming fabrics on de-watering during paper forming and the resultant paper properties; including sheet formation and the extent of MD fibre orientation and two sidedness, was investigated using the University of Melbourne (UoM) laboratory paper former. Sheets were formed from a virgin, unrefined, commercial bleached eucalypt kraft pulp (dry lap) with a small amount of fluorescent fibre: the fluorescent fibre enabled the fibre alignment distribution to be determined for each side of the sheet, A selection of six 2 1/2 layer forming fabrics were examined with the UoM sheet former operated at a nominal standard flow condition: stock consistency of 0.53 w/w%, stock flowing over the wire at 0.52 m/s, vacuum reservoir -50kPa, and with the slice set to 10mm. The sheet forming process was captured in the z-MD plane with a high speed digital imaging system which enabled the flow depth during de-watering to be measured by image analysis. The design of the forming fabric affected the drainage rate and a series of drainage curves was obtained. The effect of the forming fabrics' drainage behaviour on sheet properties is discussed.