The mechanism of paper curl is examined using an experimental apparatus that presses a sheet of paper between two flat-heated plates. When both sides of the paper are heated at different temperatures, the moisture content of the low-temperature side becomes higher than that of the high-temperature side. A difference in the moisture content causes a shrinkage difference between both sides of the paper, generating paper curl. An analysis of the paper curl amount is then carried out by calculation of moisture transport that considers the capillary flow and water evaporation. The amount of paper curl is calculated as a function of heating time using a bi-metal model. The theoretical and experimental results are in good agreement.
Shunichi Oohara, Yuko Hayama, Hirofumi Tanigawa, Takaharu Tsuruta, "Analysis of the Paper Curl Amount in the Fusing Process of Electrophotography by Calculation of Moisture Transport" in Proc. IS&T Int'l Conf. on Digital Printing Technologies and Digital Fabrication (NIP28), 2012, pp 289 - 293, https://doi.org/10.2352/ISSN.2169-4451.2012.28.1.art00005_2