Fire retardant compositions and methods and apparatuses for making the same

Abstract

A method for forming yarn provides for forming an intermediate product being a fire retardant and heat resistant cohesive elongated network of fibers in a single operation by stretching and breaking filaments of a ribbon like tow starting material of longitudinally aligned filaments. The intermediate product may be wool-like with wavy and randomly oriented fibers formed by from the fragmented filaments. The single drafting operation includes directing the tow through first and second pairs of rollers, the second pair rotating faster than the first. The intermediate product may be spun directly into yarn in one spinning/twisting operation. The fire retardant and heat resistant yarn so produced may include 100% oxidized polyacrylonitrile fibers having an average length greater than about 15 cm. The yarn may be knitted or otherwise formed into fire-retardant and heat resistant fabrics or other products used in various applications.

1 . A fire retardant and heat resistant yarn consisting essentially of 100% oxidized polyacrylonitrile (PAN) fibers, said fibers having an average length greater than about 10 cm, substantially all of said fibers having a length within a range of about 2.5 cm to about 23 cm. 
     
     
         2 . The fire retardant and heat resistant yarn as in  claim 1 , wherein said oxidized PAN fibers have an average length greater than about 15 cm. 
     
     
         3 . A fabric consisting essentially of yarn formed of a plurality of fire retardant and heat resistant fibers and no strengthening fibers, each of said fire retardant and heat resistant fibers comprising 100% polyacrylonitrile (PAN), said fibers having an average length greater than about 10 cm, a majority of said fibers having a length within a range of about 2.5 cm to about 23 cm, said PAN being one of oxidized PAN and carbonized PAN. 
     
     
         4 . The fabric as in  claim 3 , wherein said PAN comprises oxidized PAN and said fabric comprises wearing apparel. 
     
     
         5 . The fabric as in  claim 3 , wherein said PAN comprises oxidized PAN and said fabric comprises one of a jersey, a jacket lining, a boot lining, a helmet lining and a blanket. 
     
     
         6 . The fabric as in  claim 3  wherein said PAN comprises carbonized PAN. 
     
     
         7 . A fire retardant and heat resistant yarn consisting essentially of 100% carbonized polyacrylonitrile (PAN) fibers, said fibers having an average length greater than about 15 cm, substantially all of said fibers having a length within a range of about 2.5 cm to about 23 cm. 
     
     
         8 . An unencapsulated fabric consisting essentially of yarn formed of a plurality of fire retardant and heat resistant fibers and no strengthening fibers, each of said fire retardant and heat resistant fibers comprising 100% polyacrylonitrile (PAN). 
     
     
         9 . The unencapsulated fabric as in  claim 8 , wherein said PAN comprises oxidized PAN and said fabric comprises one of a jersey, a jacket lining, a boot lining, a helmet lining and a blanket. 
     
     
         10 . The unencapsulated fabric as in  claim 8 , wherein said PAN comprises carbonized PAN and said fabric comprises one of a jersey, a jacket lining, a boot lining, a helmet lining and a blanket. 
     
     
         11 . The unencapsulated fabric as in  claim 8 , wherein said PAN comprises activated and carbonized PAN and said fabric comprises one of a jersey, a jacket lining, a boot lining, a helmet lining and a blanket. 
     
     
         12 . A fire retardant and heat resistant strand of material consisting of 100% oxidized polyacrylonitrile (PAN) fibers, said fire retardant and heat resistant strand formed according to the method of: providing a starting material comprising a tow of filaments forming a ribbon; drawing said starting material through a first pair of rollers and a second downstream pair of rollers of a drafting component while urging said first pair of rollers toward each other and said second pair of rollers toward each other, said second pair of rollers having a second rotational speed that is faster than a first rotational speed of said first pair of rollers, thereby stretching and breaking said filaments of said tow of filaments to form a cohesive elongated network of fibers formed by said stretching and breaking said filaments. 
     
     
         13 . The fire retardant and heat resistant strand of material as in  claim 12 , wherein said cohesive elongated network of fibers is wool-like, generally flat and said fibers are wavy and randomly oriented within said cohesive elongated network of fibers. 
     
     
         14 . The fire retardant and heat resistant strand of material as in  claim 12 , wherein said fibers have an average length greater than about 15 cm, each said fiber having a length within a range of about 2.5 cm to about 23 cm. 
     
     
         15 . A fire retardant and heat resistant yarn consisting of 100% oxidized polyacrylonitrile (PAN) fibers, said fire retardant and heat resistant yarn formed according to the method of: providing a starting material comprising a plurality of longitudinally aligned oxidized PAN filaments with limited twists; converting said starting material into a fire retardant and heat resistant cohesive elongated network of fibers in a single operation that stretches and breaks said filaments of said starting material, thereby separating at least some of said filaments into a plurality of said fibers having lengths shorter than said corresponding filaments from which said fibers were separated; and directly spinning said cohesive elongated network of fibers into yarn in one spinning step that further twists said cohesive elongated network of fibers. 
     
     
         16 . The fire retardant and heat resistant yarn as in  claim 15 , wherein said cohesive elongated network of fibers is wool-like and said fibers are wavy and randomly oriented within said cohesive elongated network of fibers. 
     
     
         17 . The fire retardant and heat resistant yarn as in  claim 15 , wherein said fibers having an average length greater than about 10 cm, substantially all of said fibers having a length within a range of about 2.5 cm to about 23 cm. 
     
     
         18 . The fire retardant and heat resistant yarn as in  claim 15 , wherein said starting material comprises a ribbon of small filament tow with no greater than 24K filaments and said method further comprises maintaining said ribbon flat and untwisted until said converting.