Paper making machine fabric as well as tissue paper produced thereby

#The technical field, to which the invention relates, concerns the production of tissue paper on a corresponding paper making machine, in which in particular a through air drying (TAD) zone is present. A special impressing tissue is used in this TAD zone.

#The sheet formation of the paper and the three-dimensional structuring of a moist non-woven fabric which has already been formed but can still be deformed due to a high residual water content is normally carried out on supporting fabrics which originate from textile weaving processes.

#The three-dimensional structure of a moist paper sheet by the formation of zones of lesser density, which are framed by compressed zones, is carried out in modern tissue producing machines within the framework of pre-drying of the sheet in a pre-drying part before the Yankee cylinder. The pre-drying of the paper sheet is carried out on the supporting fabric by convection, in that hot air is pressed through the paper sheet which is located on the supporting fabric.

#Examples of embodiments of the invention are shown in the drawings. They show:

#FIG. 1 a schematic plan view of the top, i.e. the paper contact side of an example of an embodiment of the paper making machine fabric in accordance with the invention;

#FIG. 2 a similar schematic plan view as in FIG. 1;

#All the Figures are enlargements by comparison with the embodiment in practice.

#FIG. 1 shows schematically a paper making machine fabric, seen from the top, i.e. on the contact side of the paper sheet. It shows an area of eight weft yarns SF1 to SF8 and eight warp yarns KF1 to KF8 for the production of a complete pattern which repeats itself. Against the linen weave which is the simplest weave structure, in which the warp yarns are alternately above (cross over) and/or below (cross under) the weft yarn, and/or the weft yarns are alternately above or below the warp yarn, a cross under is replaced by a cross over in the weave pattern of FIG. 1 both in the case of the warp yarns as well as of the weft yarns at each eighth intersection. These intersection points are marked for the weft yarns by a “S” and for the warp yarns by a “I”. The corresponding weft yarns at the points marked “S” will below be described as an upper yarn weft and at the points marked “I” as under yarn weft, because there it is located below at least three warp yarns. Correspondingly at the points marked “I” the corresponding warp yarn will be described as the upper yarn chain and at the points marked “S” as the under yarn chain.

#The upper yarns in the case of both warp and weft yarns form the actual support area of the fabric (the side contacting the paper). In the case of warp and weft yarns, the under yarns form the lower level of the fabric. As is shown in FIGS. 2, 3, 5 and 6 the upper yarns can also be ground in part in planar form to form the support plane, as is already known in connection with other paper making machine fabrics.