Filament networks and methods of making same for use in the manufacture of products with enhanced characteristics

Abstract

The present invention relates to the production of filament networks that can serve as intermediates for the production of goods to impart enhanced performance characteristics such as strength and flame resistance. This filament network intermediate includes a plurality of filaments of one or more types of materials, wherein the filaments are randomly associated in the network in a wool-like configuration. The present invention also relates to a two-step process for making filament networks that may be performed by a single apparatus. The present invention further relates to an apparatus for feeding and drafting fibers to produce filament networks.

1 . A method for producing a filament network comprising the steps of: 
 a) providing at least one starting fiber comprising a plurality of longitudinally aligned filaments;    b) introducing the starting fibers into a drafting component, wherein the drafting component comprises a first pair of rollers and a second pair of rollers, wherein the second pair of rollers is downstream of the first pair, and wherein the first pair of rollers turns at a first speed and the second pair of rollers turns at a second speed;    c) drawing the starting fibers through the drafting component between the first pair of rollers and the second pair of rollers while applying pressure onto the first pair of rollers and the second pair of rollers, wherein the second speed is faster than the first speed, to form a filament network comprising a wool-like random collection of wavy filaments.    
     
     
         2 . The method of  claim 1 , wherein the second speed is between 1.1 to 50 times faster than the first speed.  
     
     
         3 . The method of  claim 1 , wherein step a) further comprises providing two precursor fibers.  
     
     
         4 . The method of  claim 1 , wherein at least one precursor fiber is a stainless steel fiber.  
     
     
         5 . The method of  claim 1 , wherein at least one precursor fiber is a polymeric material.  
     
     
         6 . The method of  claim 5 , wherein the polymeric material is an aramid fiber.  
     
     
         7 . The method of  claim 5 , wherein the polymeric material is oxidized PAN.  
     
     
         8 . The method of  claim 7 , wherein the precursor fiber has filaments of no greater than 192K.  
     
     
         9 . The method of  claim 7 , wherein the precursor fiber has filaments of no greater than 96K.  
     
     
         10 . The method of  claim 7 , wherein the precursor fiber has filaments of no greater than 48K.  
     
     
         11 . The method of  claim 1  further comprising the step of forming yarn from the filament network.  
     
     
         12 . An apparatus for drafting at least one precursor fiber comprising a plurality of longitudinally aligned filaments to form a fibrous network, wherein said apparatus comprises: 
 a) a first pair of rollers having a first rolling speed;    b) a second pair of rollers downstream from the first set of rollers having a second roller speed, wherein the second roller speed is at least 1.1 times greater than the first speed; and    c) a pressurizing element that applies pressure onto both the first and second pairs of rollers.    
     
     
         13 . The apparatus of  claim 12 , wherein the pressurizing element is a weighted element that applies pressure cooperatively onto both the first and second pair of rollers.  
     
     
         14 . The apparatus of  claim 13 , wherein the weighted element is a pendulum carrier.  
     
     
         15 . The apparatus of  claim 12 , wherein one roller in the first and second pairs of rollers is a metal roller with teeth.  
     
     
         16 . The apparatus of  claim 12 , wherein one roller in the first and second pairs of rollers has a cot with a hardness of about 75 to 90.  
     
     
         17 . The apparatus of  claim 12  further comprising an intermediate pair of rollers between the first and second pairs of rollers, and driven at an intermediate speed faster than the first speed.  
     
     
         18 . The apparatus of  claim 17 , wherein the intermediate speed is between 1.1 to 50 times faster than the first speed.  
     
     
         19 . A filament network made from a fibrous starting material, wherein the fibrous starting material further comprises a plurality of aligned individual filaments with limited twists, and wherein said filament network comprises a plurality of filaments held together by mechanical, physical and noncovalent chemical forces.  
     
     
         20 . The network of  claim 19 , wherein said fibrous starting material is fibers of the same type.  
     
     
         21 . The network of  claim 20 , wherein the fiber is a stainless steel fiber having no greater than 192K filaments.  
     
     
         22 . The network of  claim 21 , wherein each filament of the network made from the stainless fiber has a length of no greater than 40 cm.  
     
     
         23 . The network of  claim 20 , wherein the fiber is a polymeric fiber having no greater than 192K filaments.  
     
     
         24 . The network of  claim 23 , wherein each filament of the network made from the polymeric fiber has a length of no greater than 40 cm.  
     
     
         25 . The network of  claim 23 , wherein the polymeric fiber is an aramid fiber.  
     
     
         26 . The network of  claim 23 , wherein the polymeric fiber is oxidized polyacrylonitrile (PAN).  
     
     
         27 . The network of  claim 26 , wherein the oxidized PAN has a density of between 1.30 to 1.50 g/cm 3 , a carbon content of between 55 to 68%, and a Limiting Oxygen Index (LOI) value of between 40 to 60%.  
     
     
         28 . The network of  claim 26 , wherein the oxidized PAN fiber has no greater than 96K filaments of no greater than 25 micrometers in diameter in each filament.  
     
     
         29 . The network of  claim 26 , wherein each filament of the network made from the oxidized PAN fibers has a length of no greater than 40 cm, a diameter of no greater than 20 micrometers, and an average weight of no greater than 0.4 g/10 cm.