Paper machine for the production of tissue paper

DETAILED DESCRIPTION The present invention provides a paper machine for the production of tissue paper where the fiber suspension proceeds from a headbox to a sheet formation unit.
Supported by the main wire, the web is passed to a four-drinier section provided with dewatering means and from there, in pressed state, to a drier and subsequently to a winding apparatus.
The invention comprises, in one form, a paper machine for the production of a fiber web, including a headbox for forming the fiber web.
Disposed adjacent the headbox is either a dewatering unit, e.
g.
, a dewatering cylinder, a double wire former or a four-drinier wire section.
Also provided are at least one press unit for dewatering the fiber web, a tissue drying cylinder for finish drying the fiber web, a device for fiber web pickup from the tissue drying cylinder (Yankee cylinder), e.
g.
, a creping doctor or a Clupak device, and a carrier belt for carrying the fiber web.
At least one of the press units is configured as a shoe press for drying the fiber web, and includes a device for immediately separating the fiber web from a press felt after at least one press pass.
The belt is preferably water impermeable, and an adhesion force between the water impermeable belt and the fiber web is greater than an adhesion force between the press felt and the fiber web.
The inventors have recognized that, surprisingly, the drying effect of the shoe press generates a considerably higher degree of drying (about 57% dry content) than a corresponding roll press (about 47% dry content).
This, in conjunction with a nonabsorbent belt which avoids a remoistening of the web, results in considerably increased drying capacities of a press unit.