the number and the size of the slits in the sheet the upper thread composite 13 forms a relatively even contact surface over the entire surface of the paper web such that the tendency for markings is significantly reduced in general all plastics producing a fiber of high tensile strength that are capable of being spun and are temperature and vapor resistant are suitable as material for threads of the thread composite the softening temperature of the plastic used should not be below 150 u00b0 c and preferably exceed 200 u00b0 c the tensile strength of the filaments should be at least 3 cn dtex preferably exceeding 4 cn dtex stabilized polyesters are primarily suitable preferably polyethyleneterephthalate petp a plurality of polyamides pa such as polyamide 6 polyamide 6 6 polyamide 12 polyamide 6 10 polyamide 6 12 polyamide 4 6 and additionally polyphenylene sulfides pps or polyetheretherketone peek but also polyaramides especially poly n phenylene isophthalamide or poly p phenylene terephthalamide for plastics having aromatic or heterocyclic monomers the following are suitable polycarbonates polyaminotriazole polytriazole polybenzimidazole polybenzoxazole polyquinolizine or polyoxydiazole and polyoxythiadiazole polyfluoralkylene and polytetrafluorethylene ptfe may also be used mineral filaments glass filaments etc are also suited for this process carbon fibers which exhibit very high tensile strength may also be used instead of plastic fibers carbon fibers are very difficult to spin because their shearing strength is too low so that they would break during weaving however they may be made into thread composites without any problem for lateral transverse stability the carbon fibers are preferably provided with a thermofixing resin finish for example epoxy resin the threads for the thread composite should preferably be either slightly adhesive or be finished with an adhesive.