Polyolefin sheet

Abstract

A process for production of an article from a woven fabric of melt spun and drawn fibers or tapes of oriented polypropylene homopolymer or copolymer is disclosed, comprising subjecting the woven fabric of melt spun and drawn fibers or tapes to elevated temperature and pressure sufficient to melt a proportion of the polymer, characterised in that the draw ratio of said melt spun and drawn fibers or tapes is at least 7:1.

1 . Process for production of an article from a woven fabric of melt-formed fibres or tapes of oriented polypropylene homopolymer or copolymer, comprising subjecting the woven fabric of melt-formed fibres or tapes to elevated temperature and pressure sufficient to melt a proportion of the polymer, characterised in that the draw ratio of said fibres or tapes is at least 7:1.  
     
     
         2 . Process according to  claim 1 , wherein the compaction pressure does not exceed 10 MPa.  
     
     
         3 . Process according to  claim 1  or  2 , wherein the compaction pressure is between 1 and 7 MPa, preferably between 2 and 5 MPa.  
     
     
         4 . Process according to any preceding claim, wherein a single pressure is used throughout the hot compaction process.  
     
     
         5 . Process according to any preceding claim, wherein the temperature at which the fibres or tapes are compacted is no greater than the peak temperature of melting at the ambient compaction pressure  
     
     
         6 . Article comprising melt-formed fibres or tapes of oriented polypropylene homopolymer or copolymer in the form of a woven fabric which has been subjected to hot compaction, characterised in that said fibres or tapes have a draw ratio of at least 7:1.  
     
     
         7 . Article or process according to any preceding claim, wherein the article is monolithic.  
     
     
         8 . Article or process according to any preceding claim, wherein the draw ratio is at least 8:1, preferably at least 9:1.  
     
     
         9 . Article or process according to  claim 8 , wherein the draw ratio is 9:1 to 15:1, preferably 9:1 to 11:1.  
     
     
         10 . Article or process according to any preceding claim, wherein the fibres or tapes of the oriented polypropylene homopolymer or copolymer have a weight average molecular weight (Mw) in the range of 100,000 to 800,000.