Poly(butylene terephthalate) sewing thread

Abstract

The present invention provides a sewing thread formed from poly(butylene terephthale) multifilament yarns, the sewing thread being characterized in that the sewing thread has an elastic recovery at 20% elongation of greater than or equal to 60%, a method of producing same, and the use of same. In the present invention a PBT yarn designates a yarn composed of a polyester that uses butylene terephthalate (tetramethylene terephthalate) repeating units as principal repeating units and that contains the butylene terephthalate repeating units in an amount of 50 mol-% or more, preferably 70 mol-% or more, even more preferably by 90 mol-% or more. The yarn made from PBT can contain a third component as an other acid component and/or glycol components and or other additives or colours in a total amount of 50 mol-% or less.

1 . Sewing thread comprising one or more multifilament yarns, wherein one or more of said multifilament yarns comprise(s) poly(butylene terephthalate).  
   
   
       2 . Sewing thread according to  claim 1 , wherein said poly(butylene terephthalate) multifilament yarn is made of a polyester comprising butylene terephthalate repeating units as principal repeating units in an amount of 50 mol-% or more.  
   
   
       3 . Sewing thread according to  claim 2 , wherein said polyester comprises 70 mol-% or more butylene terephthalate.  
   
   
       4 . Sewing thread according to  claim 2 , wherein said polyester comprises 90 mol-% or more butylene terephthalate.  
   
   
       5 . Sewing thread according to  claim 2 , wherein said polyester comprises further repeat units from components selected from the group containing aliphatic, alicyclic and aromatic dicarboxylic acids, other than terephthalic acid; aliphatic, alicyclic and polyether glycols, other than butylene glycol.  
   
   
       6 . Sewing thread according to  claim 1 , wherein said poly(butylene terephthalate) multifilament yarn comprises additives and/or colours.  
   
   
       7 . Sewing thread according to  claim 1 , wherein said multifilament yarns are plied together.  
   
   
       8 . Sewing thread according to  claim 1 , wherein said multifilament yarns are false twisted or air textured.  
   
   
       9 . Sewing thread according to  claim 1 , wherein said multifilament yarns are sheathed with natural or synthetic fibres.  
   
   
       10 . Sewing thread according to  claim 1 , wherein said multifilament yarns are bonded together.  
   
   
       11 . Sewing thread according to  claim 1 , wherein the sewing thread has an elastic recovery from a 20% elongation of greater than or equal 60% and an elongation at break of greater than or equal to 25%.  
   
   
       12 . Sewing thread according to  claim 1 , wherein the sewing thread has a breaking strength of from 20 to 50 cN/tex and an elongation at break of from 25 to 100%.  
   
   
       13 . A method of producing a plied sewing thread, comprising the steps of: doubling and twisting multifilament yarns, whereby at least one of the multifilament yarns is made from poly(butylene terephthalate), having titer of greater than or equal 20 dtex to give a doubled, tripled or quadrupled twisted thread, dyeing the resultant thread, and coating the dyed thread with a sewing thread lubricant and/or a smoothing agent and/or a binder or a mixture thereof.  
   
   
       14 . A method of producing a plied sewing thread, comprising the steps of: twisting a multifilament yarn made from poly(butylene terephthalate) and having titer of from 20 to 550 dtex to give from 200 to 1800 T/m in S-direction, jointly twisting two or three of the resultant S-twisted yarns to give from 180 to 1600 T/m in Z-direction, dyeing the resultant Z-twisted thread, and coating the resultant dyed thread with a sewing thread lubricant and/or a smoothing agent and/or a binder or a mixture thereof.  
   
   
       15 . A method of producing a core spun sewing thread, wherein a sheath of natural or synthetic fibers is wrapped around a multifilament yarn made from poly(butylene terephthalate).  
   
   
       16 . A method of producing an air-intermingled sewing thread, comprising the steps of: feeding a first multifilament yarn made from poly(butylene terephthalate) through an air texturing jet to form a core yarn, and feeding a second multifilament yarn through the same said air texturing jet at a higher overfeed than said core yarn.  
   
   
       17 . A method of producing a bonded sewing thread, comprising the steps of: plying two or more multifilament yarns, whereby one or more of said multifilament yarns are made from poly(butylene terephthalate), and bonding them together with a polymeric binder.  
   
   
       18 . Use of poly(butylene terephthalate) for manufacturing at least one multifilament yarn of a sewing thread.  
   
   
       19 . Use of multifilament yarns made from poly(butylene terephthalate) for manufacturing a plied, core-spun, intermingled or bonded sewing thread.  
   
   
       20 . Use of poly(butylene terephthalate) sewing thread according to  claim 13  for sewing seams in stretch fabrics.