| 摘要 |
<p>A method for treating a fibrous web with a belt calender, which comprises a belt arranged to circulate around at least one guide means, outside which belt is arranged at least one counterpart forming a contact surface with the belt, so that between the belt and the counterpart is formed a web calendering area through which the web to be treated is led. In the method, the temperature of the pressing surfaces is adjusted to a value which exceeds the boiling point of the liquid in the fibrous web corresponding to the pressure caused by the belt tension, the fibrous web to be calendered is led through the calendering area, whereby the surfaces of the calendering area conduct heat to the web, which vaporises the liquid, and the steam pressure increases to correspond to the external pressure caused by the surfaces. As the conduction of heat still continues, vaporisation continues, whereby the steam pressure causes the contact between the surface and the web to deteriorate, thus bringing about a state in the process where the surfaces of the web almost reach the temperature of the pressing surfaces, while the interior of the web is at a temperature corresponding to the pressure caused by the said belt tension, whereupon steep, internal thermal and moisture gradients are formed in the web.</p> |
