be produced by any of the methods for producing nonwovens known in the prior art as described for example in ullmann 39 s encyclopedia of industrial chemistry vol a 17 vch weinheim 1994 pages 572 u2013 581 nonwovens produced by the dry laid process or by the spunbond process or by the melt flow process are preferred the dry laid process starts out from staple fibers which are normally first separated into individual fibers by carding and are then laid together to form the unstabilized nonwoven using an aerodynamic or hydrodynamic process the unstabilized nonwoven is then heat treated u201c thermobonded u201d to give the final nonwoven to this end the synthetic fibers are either heated to the extent that their surface melts and the individual fibers are joined together at their points of contact or the fibers are coated with an additive which melts during the heat treatment and thus bonds the individual fibers together the individual bonds are fixed by cooling besides this process any other processes used in the prior art for bonding nonwovens may of course also be used by contrast the spunbond process starts out from individual filaments formed by melt spinning from extruded polymers which are forced under high pressure through spinning jets the filaments issuing from the spinning.