Patent ID: 8635846

Claim:
A method for making a fire retardant fabric comprising: providing at least one tow of oxidized polyacrylonitrile fibers having a fineness of about 0.5 to about 1.5 denier per fiber; providing an apparatus for converting a tow of said oxidized polyacrylonitrile fibers into said yarn, said apparatus comprising a feed section including at least one spool removably mounted thereon, said feed section being operably coupled to a drafting section comprising a first roller pair and a second roller pair, said drafting section being operably coupled to a spinning section comprising at least one bobbin removably mounted thereon; positioning said tow of oxidized polyacrylonitrile fibers on said at least one spool, said fibers being longitudinally aligned with one another in a generally flat and untwisted form; pulling said tow from said spool by unwinding and applying tension thereby maintaining said tow in said generally flat and untwisted form and feeding said generally flat and untwisted tow to said drafting component; stretching and breaking said fibers of said tow to form a cohesive elongated network of fibers, in said drafting component by directing said tow through said first and second roller pairs while applying pressure to said first and second roller pairs, said first roller pair having substantially conterminous opposed surfaces and spinning at a first speed and said second roller pair being downstream and having substantially conterminous opposed surfaces and spinning at a second, faster speed, said pressure urging said second roller pair toward each other and said first roller pair toward each other; spinning and twisting said cohesive elongated network of fibers onto said bobbin thereby forming said yarn and wherein said spinning and twisting causes said yarn to have a twist count of about 100 twists per meter to about 800 twists per meter; wherein said providing said tow, said pulling, said applying tension, said stretching and breaking and said spinning and twisting all take place in a single pass through said apparatus; and forming said yarn into a fire retardant fabric by at least one of a knitting, a weaving, a braiding and a stitch-bonding process.