Method for making propylene monofilaments, propylene monofilaments and their use

Abstract

In a process for manufacturing monofilaments of a polypropylene having a melt flow index (MFI) at 230° C./2.16 kg of 2 to 16 g/10 min and possessing a diameter of greater than 0.050 mm and an improved abrasion resistance, from 20 to 0.1% by weight of an additive is added to the polypropylene upstream of the extruder, the melt is spun into a water bath, drawn into monofilaments and the monofilaments are wound up. The monofilament of a polypropylene having a melt flow index (MFI) at 230° C./2.16 kg of 2 to 16 g/10 min and possessing a diameter of greater than 0.050 mm and an improved abrasion resistance has a strength of at least 50 cN/tex for an elongation corresponding to the maximum tensile stress (elongation at break) of less than 30%. It also has an abrasion of less than 0.05% and a relative fracture energy>100% after treatment for 24 hours at 120° C.

1 - 10 . (canceled)  
     
     
         11 . A process for manufacturing monofilaments of a polypropylene having a melt flow index (MFI) at 230° C./2.16 kg of 2 to 16 g/10 min and possessing a diameter of greater than 0.050 mm and an improved abrasion resistance, said process comprising the steps of: 
 a) adding from 20 to 0.01% by weight of an additive to the polypropylene upstream of the extruder,    b) spinning the melt into a water bath,    c) drawing into said monofilaments,    d) and winding up the monofilaments.    
     
     
         12 . The process according to  claim 11 , wherein the additive is 0.5 to 1.2% by weight of a combination of lubricant, filler and heat stabilizer.  
     
     
         13 . The process according to  claim 11 , wherein the additive is 0.05 to 1% by weight of a lubricant.  
     
     
         14 . The process according to  claim 11 , wherein the additive is 0.01 to 1.0% by weight of fillers.  
     
     
         15 . The process according to  claim 11 , wherein the additive is 0.1 to 0.8% by weight of a heat stabilizer.  
     
     
         16 . The process according to  claim 11 , wherein the additive is 1 to 20% by weight of a polypropylene/polyethylene copolymer possessing a melting point≧140° C.  
     
     
         17 . Monofilaments of a polypropylene having a melt flow index (MFI) at 230° C./2.16 kg of 2 to 16 g/10 min and possessing a diameter of greater than 0.050 mm and an improved abrasion resistance, a strength of at least 50 cN/tex for an elongation corresponding to the maximum tensile stress (elongation at break) of less than 35%.  
     
     
         18 . Monofilaments according to  claim 17 , wherein the maximum tensile stress is less than 30%.  
     
     
         19 . Monofilaments according to  claim 17 , further having an abrasion of less than 0.05%.  
     
     
         20 . Monofilaments according to  claim 17 , further having a relative fracture energy>100% after treatment for 24 hours at 120° C.  
     
     
         21 . A two-dimensional article for filtration in the chemical, pharmaceutical and food industries made from monofilaments as defined in claim  7 .