Industrial fabric, method for producing a nonwoven, and use of an industrial fabric

Abstract

An industrial fabric ( 30, 40, 45 ) is provided, in particular for transporting a nonwoven web while producing same, having a product side (PS), which is in contact with the nonwoven, and a machine side (MS), which is in contact with transport devices of a system ( 1 ) for producing the nonwoven. The fabric ( 30, 40, 45 ) has MD threads ( 32, 33, 43, 44, 48, 50 ), which run in the running direction of the nonwoven web, and CMD threads ( 31, 41, 42, 52 ), which run perpendicularly to the MD threads, said threads being woven together. At least two layers of MD threads ( 32, 33, 43, 44, 48, 50 ) are provided which are stacked one over the other in pairs and form product contact MD threads ( 32, 43, 50 ) and non-product contact MD threads ( 33, 44, 48 ). At least the material of each product contact MD thread ( 32, 43, 50 ) facing the product side (PS) forms a contact angle, measured according to the Wilhelmy plate method, of at least 80°, preferably at least 90°, more preferably at least 100°. In order to prevent the adhesion of threads to the fabric ( 30, 40, 45 ) and in order to reduce the air permeability, the fabric has a single layer of CMD threads ( 31, 41, 42, 52 ), and the cross-section of each product contact MD thread ( 32, 43, 50 ) has at least two regions, a first region of which is formed of the first material and a second region of which is formed of the second material. A substantial proportion, preferably a predominant proportion, of a tensile force acting on each product contact MD thread ( 32, 43, 50 ) can be transmitted from the second region, and the cross-section of the product contact MD threads ( 32, 43, 50 ) have a second region in the form of a core ( 61 ) and a first region in the form of a casing ( 62 ) which surrounds the core ( 61 ). The product MD threads ( 32, 43, 50 ) are preferably coextruded or are extruded in two successive steps. The MD threads ( 32, 33, 43, 44, 48, 50 ) have a flattened cross-section, preferably a rectangular cross-section, wherein a ratio of a height of the cross-section to a width of the cross-section preferably ranges from 1:1.2 to 1:10, preferably from 1:1.5 to 1:4. The invention further relates to a method for producing a nonwoven and to the use of an industrial fabric ( 30, 40, 45 ).

1 . An industrial fabric ( 30 ,  40 ,  45 ,  70 ) for transporting a web of a nonwoven, the industrial fabric comprising a product side (PS) that is adapted to be in contact with the nonwoven, and a machine side (MS) that is adapted to be in contact with conveying devices of a system ( 1 ) for producing the nonwoven, at least two layers of MD threads ( 32 ,  33 ,  43 ,  44 ,  48 ,  50 ,  72 ,  73 ) adapted to be oriented in a running direction of a web of the nonwoven and CMD threads ( 31 ,  41 ,  42 ,  52 ) that are oriented perpendicular to the MD threads and are interwoven with the at least two layers of the MD threads, the at least two layers of MD threads ( 32 ,  33 ,  43 ,  44 ,  48 ,  50 ,  72 ,  73 ) are arranged stacked in pairs one above and below each other, and form product contact MD threads ( 32 ,  43 ,  50 ,  72 ,  73 ) and non-product contact MD threads ( 33 ,  44 ,  48 ), at least a surface of the respective product contact MD threads ( 32 ,  43 ,  50 ,  72 ,  73 ) facing the product side (PS) has a first material that has a contact angle, measured according to the Wilhelmy plate method, of at least 80°, the CMD threads ( 31 ,  41 ,  42 ,  52 ) are arranged in a single layer, and each cross section of the product contact MD threads ( 32 ,  43 ,  50 ,  72 ,  73 ) has at least first and second areas, the first area is made from a first material and the second area is made from a second material, wherein a majority of a tensile force acting on the respective product contact MD threads ( 32 ,  43 ,  50 ) is transferred by the second area and the second area of the product contact MD threads ( 32 ,  43 ,  73 ,  73 ) is formed as a core ( 61 ) and the first area is formed as a casing ( 62 ) surrounding the core ( 61 ), wherein the product contact MD threads ( 32 ,  43 ,  50 ,  72 ,  73 ) have a flattened cross section, and a ratio of a height of the cross section to a width of the cross section is between 1:1.2 and 1:10. 
     
     
         2 . The industrial fabric ( 30 ,  40 ,  45 ,  70 ) according to  claim 1 , wherein the first area is made from a fluorine-containing polymer or copolymers of polyethylene with the fluorine-containing polymer. 
     
     
         3 . The industrial fabric ( 30 ,  40 ,  45 ,  70 ) according to  claim 1 , wherein the second area is made from polyamide, polyphenylene sulfide, polyether ether ketone, polypropylene, aramid, polyethacetone, or polyethylene naphthalate. 
     
     
         4 . The industrial fabric ( 30 ,  40 ,  45 ,  70 ) according to  claim 1 , wherein at least one material facing the product side (PS) of at least said CMD threads ( 31 ,  41 ,  42 ,  52 ) that are adapted to contact the web of the nonwoven have a contact angle, measured according to the Wilhelmy plate method, of at least 80°. 
     
     
         5 . The industrial fabric ( 30 ,  40 ,  45 ,  70 ) according to  claim 1 , wherein the CMD threads ( 31 ,  41 ,  42 ,  52 ) have a round cross section. 
     
     
         6 . The industrial fabric ( 30 ,  40 ,  45 ) according to  claim 5 , wherein the CMD threads include first CMD threads ( 41 ) with a larger diameter and second CMD threads ( 42 ) with a smaller diameter that are alternately arranged one behind the other in a direction of the MD threads ( 43 ,  44 ), and the second CMD threads ( 42 ) with the smaller diameter are engaged with the MD threads ( 43 ,  44 ) and at least one surface of the second CMD threads ( 42 ) with the smaller diameter facing the product side is made from a material that has a contact angle, measured according to the Wilhelmy plate method, of at least 80°. 
     
     
         7 . The industrial fabric ( 30 ,  40 ,  45 ,  70 ) according to  claim 1 , wherein at least one of the MD threads ( 32 ,  33 ,  43 ,  44 ,  48 ,  50 ) or the CMD threads ( 31 ,  41 ,  42 ,  52 ) are monofilaments. 
     
     
         8 . The industrial fabric ( 30 ,  40 ,  45 ,  70 ) according to  claim 1 , wherein at least one part of at least one of the MD threads ( 32 ,  33 ,  43 ,  44 ,  48 ,  50 ) or the CMD threads ( 31 ,  41 ,  42 ,  52 ) is electrically conductive, and includes
 carbon on an outer casing of the cross section of the at least one of the MD threads or CMD threads,   
       or
 carbon nanotubules are contained in the material of the at least one of the MD threads ( 32 ,  33 ,  43 ,  44 ,  48 ,  50 ) or the CMD threads ( 31 ,  41 ,  42 ,  52 ). 
 
     
     
         9 . The industrial ( 30 ,  40 ,  45 ,  70 ) according to  claim 1 , wherein the fabric is closed by a seam connecting two fabric ends to form an endless conveyor belt, the seam is a spiral seam that has two seam spirals ( 74 ) that extend over an entire width of the conveyor belt and are turned in or hooked into loops ( 71 ) of the MD threads ( 72 ,  73 ) of opposing fabric ends and both are coupled with each other by a closing wire extending over the entire width of the conveyor belt. 
     
     
         10 . The industrial fabric ( 30 ,  40 ,  45 ) according to  claim 9 , wherein the seam spirals ( 74 ) include a thread ( 75 ) having a cross section with a core ( 76 ) and a casing ( 77 ) surrounding the core ( 76 ), the casing ( 77 ) is made from a material that has a contact angle, measured according to the Wilhelmy plate method, of at least 80°. 
     
     
         11 . The industrial fabric according to  claim 1 , wherein a cross-sectional area of the threads ( 31 ,  32 ,  33 ,  41 ,  42 ,  43 ,  44 ,  48 ,  50 ,  72 ,  73 ) is at least 0.0003 mm 2 . 
     
     
         12 . A method for producing a nonwoven that is aerodynamically formed and at least one of chemically or thermally cured, comprising: moving a web of the nonwoven is on a surface of a conveyor belt ( 9 ,  12 ,  15 ) made from an industrial fabric ( 30 ,  40 ,  45 ) according to  claim 1 . 
     
     
         13 . A method of using an industrial fabric ( 30 ,  40 ,  45 ) according to  claim 1 , comprising: forming the industrial fabric into a conveyor belt ( 9 ,  12 ,  15 ) for transporting a web of a nonwoven during its production, and carrying the web of the nonwoven during its thermal hardening through molten material processing or chemical hardening through curing either in a drying device ( 8 ) or curing device ( 14 ). 
     
     
         14 . The industrial fabric ( 30 ,  40 ,  50 ) according to  claim 1 , wherein the product contact MD threads are coextruded or extruded in two successive steps. 
     
     
         15 . The industrial fabric ( 30 ,  40 ,  50 ) according to  claim 1 , wherein the fluorine containing polymer is a PVDF, an ETFE, or a PTFE polymer.