Polypropylene composition with improved tensile properties, fibers and nonwoven structures

Abstract

A polypropylene composition is described having an MFI measured according to ISO 1133 for polypropylene of 1 to 3 g/10 min and a xylene soluble content in the range from 1 wt % to 4.5 wt % or 1.5 wt % to 4.5 wt %, which can be used to produce spun and drawn fibres having an average MFI measured according to ISO 1133 for polypropylene of 1 to 5 g/min, a xylene soluble content in the range from 1 wt % to 4.5 wt % or 1.5 wt % to 4.5 wt %, the spun and drawn fibres having an average elongation of at least 65% as measured by ISO 5079 with an adjusted testing speed of 80 mm/min, and/or an average tenacity/tensile strength of at least 56 c N/tex as measured by ISO 5079 with an adjusted testing speed of 80 mm/min.

1 . Spun and drawn fibres comprising a polypropylene composition of a polypropylene homopolymer, the spun and drawn fibres having an average MFI measured according to ISO 1133 for polypropylene of 1 to 5 g/10 min and a xylene soluble content in the range from 1 wt % to 4.5 wt % or 1.5 wt % to 4.5 wt %, the spun and drawn fibres having:
 an average elongation of at least 65% as measured by ISO 5079 with an adjusted testing speed of 80 mm/min, and/or   an average tenacity/tensile strength of at least 56 cN/tex as measured by ISO 5079 with an adjusted testing speed of 80 mm/min.   
     
     
         2 . The spun and drawn fibres of  claim 1 , wherein the polypropylene composition consists of one or more polypropylene homopolymers. 
     
     
         3 . The spun and drawn fibres of  claim 1 , wherein the fibres are staple fibres or short cut fibres. 
     
     
         4 . The spun and drawn fibres of  claim 1 , wherein the spun and drawn fibres have an average MFI of 2 to 4 g/10 min. 
     
     
         5 . The spun and drawn fibres of  claim 1 , wherein the fibres have a multilobal cross-section. 
     
     
         6 . The spun and drawn fibres of  claim 5 , wherein the fibres have a trilobal, cross-section. 
     
     
         7 . The spun and drawn fibres of  claim 1 , wherein the fibres are multicomponent fibres. 
     
     
         8 . The spun and drawn fibres of  claim 7 , wherein the fibres are bicomponent fibres. 
     
     
         9 . The spun and drawn fibres according to claim  1 , wherein the fibres have a titer of at least 1 dtex and at most 100 dtex. 
     
     
         10 . The spun and drawn fibres according to  claim 1 , wherein the polypropylene composition comprises a first and a second polymer being a blend or a multimodal polymer composition. 
     
     
         11 . The spun and drawn fibres according to  claim 1 , having an average tenacity/tensile strength in the range 56-70 cN/tex; with 75-90% extension to break. 
     
     
         12 . The spun and drawn fibres according to  claim 7 , wherein the polypropylene composition forms a core of the multicomponent fibers. 
     
     
         13 . Nonwoven comprising the spun and drawn fibres of  claim 1 . 
     
     
         14 . A geotextile comprising the non-woven of  claim 13 . 
     
     
         15 . Process for the production of spun and drawn fibres according to  claim 1 , comprising the steps of:
 a) providing the polypropylene composition to an extruder;   b) melt-spinning said polypropylene composition from a number of openings, to form molten filaments; and   c) cooling the molten filaments obtained by step (b) to obtain solidified fibres.   
     
     
         16 . The process of  claim 15 , wherein the fibres are drawn at a draw ratio of 2 to 4. 
     
     
         17 . The process of  claim 15 , wherein a polymer temperature in the extruder measured at an outlet of the extruder and/or a spin beam, is in the range of 255° C. to 350° C., preferably in the range of 265° C. to 340° C., more preferably in the range of 275° C. to 330° C. and most preferably in the range of 285° C. to 320° C. 
     
     
         18 . A polypropylene composition of a polypropylene homopolymer having a MFI measured according to ISO 1133 of 1 to 3 g/10 min and a xylene soluble content in the range 1 wt % to 4.5 wt % or 1.5 wt % to 4.5 wt %. 
     
     
         19 . A polypropylene composition according to  claim 18  having a xylene soluble content in the range from 1 wt % to 2 wt %, or 1 wt % to 3 wt %, or 1 wt % to 3.5 wt % or 1.5 wt % to 3.5 wt %, or in the range of 1 wt % to 2.5 wt % or 1.5 wt % to 2.5 wt %. 
     
     
         20 . A polypropylene composition according to  claim 18 , wherein the polypropylene composition consists of one or more polypropylene homopolymers. 
     
     
         21 . A polypropylene composition according to  claim 18 , wherein the polypropylene composition comprises a first and a second polymer being a blend or a multimodal polymer composition. 
     
     
         22 . Bicomponent fibres according to  claim 8 , comprising a sheath and a core, wherein the core comprises a polypropylene composition of a polypropylene homopolymer having a MFI measured according to ISO 1133 of 1 to 3 g/10 min and a xylene soluble content in the range 1 wt % to 4.5 wt % or 1.5 wt % to 4.5 wt %. 
     
     
         23 . Bicomponent fibres according to  claim 22 , having an average tenacity/tensile strength in the range 56-70 cN/tex; with 75-90% extension to break.