Polyester yarn and airbags employing certain polyester yarn

Abstract

Airbag cushions manufactured from polyester yarn having certain levels of intrinsic viscosity (IV) and certain specific carboxyl end group (“CEG”) levels perform unexpectedly well in high temperature and high humidity environments for airbag cushion applications. This specification identifies certain polyester yarns and characteristics of such polyester yarns that are necessary to achieve unexpectedly good performance in such high humidity and high temperature applications. A polymeric polyester yarn for airbags, said yarn having a high degree of tenacity even after a long period of exposure to high temperature and high humidity conditions is disclosed. In one aspect of the invention, a polyester yarn having CEG of less than about 60 equivalents/10 6 gram, and more preferably less than about 30 equivalents/10 6 grams, is particularly useful. In another embodiment, a polyester yarn having an IV value of at least about 0.6 performs exhibits superior properties.

1 . An airbag comprised in part of woven polymeric polyester yarn, said polyester yarn exhibiting superior hydrolytic resistance, said yarn being capable of characterization by a carboxyl end group (CEG) value, wherein said yarn provides a CEG value of less than about 30 equivalents/10 6  grams after said yarn is exposed for at least about 336 hours to a temperature of at least about 85 degrees Centigrade and a relative humidity of at least about 95 percent.  
   
   
       2 . The airbag of  claim 1  wherein said yarn further exhibits an IV value of at least about 0.6.  
   
   
       3 . The airbag of  claim 1  wherein said yarn further exhibits an IV value of at least about 0.7.  
   
   
       4 . The airbag of  claim 1  wherein said yarn further exhibits an IV value of between about 0.5 and about 0.8  
   
   
       5 . The airbag of  claim 1  wherein said yarn provides a tensile strength of at least about 400 lbs after said exposure.  
   
   
       6 . The airbag of  claim 1  wherein the calculated percentage of broken ester bonds in said yarn after said exposure is less than about 0.3 percent.  
   
   
       7 . The airbag of  claim 1  wherein the calculated percentage of broken ester bonds in said yarn after said exposure is less than about 0.1 percent.  
   
   
       8 . The airbag of  claim 1  wherein said yarn further comprises chemical inhibitors or end group capping agents which serve to improve the overall hydrolytic resistance of said polyester yarn.  
   
   
       9 . A polymeric polyester yarn for use in airbags, said yarn exhibiting: 
 (a) a CEG value of less than about 60 equivalents/10 6  grams after said yarn is exposed for at least about 3000 hours to a temperature of at least about 85 degrees Centigrade and a relative humidity of at least about 95 percent, according to ASTM D5427 as modified; and    (b) an IV value of at least about 0.6.    
   
   
       10 . An airbag cushion, said airbag cushion comprising polyester yarn, said polyester yarn having a CEG value—of less than about 60 equivalents/10 6  grams after said yarn is exposed for at least about 3000 hours to a temperature of at least about 85 degrees Centigrade and a relative humidity of at least about 95 percent.  
   
   
       11 . The airbag cushion of  claim 10  wherein said yarn further exhibits an IV value of at least about 0.6.  
   
   
       12 . The airbag cushion of  claim 10  wherein said yarn further exhibits an IV value of at least about 0.7.  
   
   
       13 . The airbag cushion of  claim 10  wherein said yarn further exhibits an IV value of between about 0.5 and about 0.8.  
   
   
       14 . The airbag cushion of  claim 10  wherein said yarn provides a tensile strength of at least about 400 lbs when tested in accordance with ASTM standard D5034 after said exposure.  
   
   
       15 . The airbag cushion of  claim 10  wherein the calculated percentage of broken ester bonds in said yarn after said exposure is less than about 0.3 percent.  
   
   
       16 . The airbag cushion of  claim 10  wherein the calculated percentage of broken ester bonds in said yarn after said exposure is less than about 0.1 percent.  
   
   
       17 . The airbag cushion of  claim 10  wherein said said polyester yarn further comprises chemical inhibitors or end group capping agents which serve to improve the hydrolytic resistance of said polyester yarn.  
   
   
       18 . An airbag comprised at least in part of woven polymeric polyester yarn, said polyester yarn exhibiting superior hydrolytic resistance, said yarn being capable of being characterized by a carboxyl end group value (CEG), said yarn further being capable of being characterized by an intrinsic viscosity (IV) value, wherein said yarn provides, after said yarn is exposed for at least about 3000 hours to a temperature of at least about 85 degrees Centigrade and a relative humidity of at least about 95 percent, the following: 
 (a) an IV value of at least about 0.6; and    (b) a CEG value of less than about 60 equivalents/10 6  grams, and    (c) a tensile strength of at least about 400 lbs.    
   
   
       19 . An airbag comprised in part of woven polymeric polyester yarn, said polyester yarn exhibiting superior hydrolytic resistance, said yarn being capable of being characterized by a carboxyl end group (CEG) value, wherein said yarn provides a CEG value of less than about 30 equivalents/10 6  grams after said yarn is exposed for at least about 336 hours to a temperature of at least about 85 degrees Centigrade and a relative humidity of at least about 95 percent, and further wherein said aged yarn after said exposure provides a tensile strength of at least about 400 lbs.  
   
   
       20 . An airbag cushion comprising: 
 at least one fabric portion including polyester yarn, said polyester yarn exhibiting a CEG value of less than 30 equivalents/10 6  grams and IV value greater than 0.6.    
   
   
       21 . The airbag cushion of  claim 20  wherein the tensile strength of said fabric portion is greater than about 275 lbs after exposure.  
   
   
       22 . The airbag of  claim 20  wherein the tensile strength of said fabric portion is greater than about 400 lbs after exposure.  
   
   
       23 . A woven airbag comprising polyester yarn, said polyester yarn exhibiting a CEG value of less than about 30 equivalents/10 6  grams and an IV value greater than about 0.6.  
   
   
       24 . The airbag of  claim 23  wherein said CEG value is less than about 50 equivalents/10 6  grams after exposure to at least about 3000 hours at a temperature of at least about 85 degrees Centigrade and a relative humidity of at least about 95 percent.  
   
   
       25 . The airbag of  claim 23  wherein said CEG value is less than about 40 after exposure to at least about 3000 hours at a temperature of at least about 85 degrees Centigrade and a relative humidity of at least about 95 percent.  
   
   
       26 . An airbag comprised of polyester yarn, said polyester yarn retaining at least about 85% of the tensile strength of said yarn after said yarn is exposed for at least 1000 hours at a temperature of at least about 85 degrees Centigrade and a relative humidity of at least about 95 percent.  
   
   
       27 . An airbag comprised of polyester yarn, said polyester yarn retaining at least about 85% of the tensile strength of said yarn after said yarn is exposed to at least about 3000 hours at temperature of at least about 85 degrees Centigrade and a relative humidity of at least about 95 percent.