Method and apparatus for making nonwoven from continuous filaments

Abstract

An apparatus for making nonwoven has a spinning device for spinning continuous filaments and moving the spun filaments in a vertical travel direction along a vertical travel path and a mesh belt below the spinning device, traveling in a horizontal direction, and having a multiplicity of vertically throughgoing openings distributed generally uniformly over its surface and of which a portion are plugged. A cooler and a stretcher are provided along the path downstream of the spinning device and above the belt for cooling and stretching the filaments and depositing the cooled and stretched filaments at a predetermined deposition location on the belt. A blower underneath the belt at the deposition location aspirates air through the openings and thereby holds the deposited filaments down on the belt.

We claim: 
     
         1 . An apparatus for making nonwoven, the apparatus comprising:
 a spinning device for spinning continuous filaments and moving the spun filaments in a vertical travel direction along a vertical travel path;   a mesh belt below the spinning device, traveling in a horizontal direction, and having a multiplicity of vertically throughgoing openings distributed generally uniformly over its surface and of which a portion are plugged;   a cooler and a stretcher along the path downstream of the spinning device and above the belt for cooling and stretching the filaments and depositing the cooled and stretched filaments at a predetermined deposition location on the belt;   means underneath the belt below the cooling and stretching devices for aspirating air through the openings and thereby holding the deposited filaments down on the belt, the openings being dimensioned and the air being aspirated through the belt such that, if none of the openings were plugged, air would pass through the belt at 300 to 1100 cfm, but actually so many of the openings are plugged that air passes through the belt at 150 to 700 cfm.   
     
     
         2 . The apparatus defined in  claim 1 , wherein the mesh belt is formed by a textile having warp filaments and weft filaments that define the mesh belt openings. 
     
     
         3 . The apparatus defined in  claim 2 , wherein the textile of the mesh belt has a web density of 20 to 75 warp filaments per 25 mm and 10 to 50 weft filaments per 25 mm. 
     
     
         4 . The apparatus defined in  claim 1 , wherein a minimum diameter of a plugged opening of the mesh belt amounts to at least 1.5 mm and a maximum of 8 mm. 
     
     
         5 . The apparatus defined in  claim 1 , wherein a ratio of air permeability of an unplugged mesh belt to an air permeability of the partly plugged mesh belt amounts to 1.2 to 4. 
     
     
         6 . The apparatus defined in  claim 1 , wherein the plugged belt openings are plugged by a sealing compound that is in or below a surface of the mesh belt and does not project past the mesh-belt surface more than a maximum of 1.5 mm. 
     
     
         7 . The apparatus defined in  claim 1 , wherein the plugged openings are arrayed in punctate or linear fashion. 
     
     
         8 . The apparatus defined in  claim 7 , wherein the plugged openings are arrayed uniformly in a regular pattern on the mesh belt. 
     
     
         9 . The apparatus defined in  claim 1 , wherein the cooler and stretcher together form a closed subassembly such that, except for a supply of cooling air in the cooler, no further air enters this closed subassembly. 
     
     
         10 . The apparatus defined in  claim 1 , further comprising, downstream of the stretcher and upstream of the deposition location:
 a diffuser through which the filaments can be guided to the deposition location prior to being deposited.   
     
     
         11 . The apparatus defined in  claim 1 , further comprising, downstream in the belt-travel direction from the deposition location:
 a compacting roller for preconsolidating the nonwoven deposited on the deposition device or on the mesh belt; and   means for heating the compacting roller.   
     
     
         12 . A method of making nonwoven comprising the steps of:
 spinning continuous filaments from a spinneret to move along a vertical travel path in a vertical travel direction;   cooling and stretching the filaments downstream from of the spinneret in a cooler and a stretcher;   depositing the cooled and stretched filament at a deposition location on a mesh belt moving horizontally underneath the cooler and stretcher and having an array of openings of which a portion are plugged;   drawing air downward through the unplugged openings in the mesh belt to stabilize the filaments deposited on the mesh belt, the air being aspirated through the mesh belt at the location at a rate forming a ratio to a rate if none of the openings were plugged of 1.2 to 4.   
     
     
         13 . The method defined in  claim 12 , wherein the nonwoven is produced as spunbond nonwoven. 
     
     
         14 . The method defined in  claim 12 , wherein the air is aspirated through deposition location at an aspiration speed of 5 to 25 m/s. 
     
     
         15 . The method defined in  claim 12 , further comprising the step of:
 preconsolidating the deposited nonwoven into final form.   
     
     
         16 . The method defined in  claim 12 , further comprising the step, to separate the nonwoven from the mesh belt, of blowing air through the mesh belt from below or against the underside of    
     
     
         17 . A spunbond nonwoven comprising continuous filaments of thermoplastic made by the method of  claim 12 , the continuous filaments have a titer of 0.9 to 10 denier. 
     
     
         18 . A melt-blown nonwoven of continuous thermoplastic filaments made by the method of  claim 12 . wherein the continuous filaments have a diameter of 0.1 to 10 μm.