Equipment and Methods for Preparing Curved Fibers

Abstract

The invention is related in general to equipment and methods for preparing curved fibers in a batch or continuous process. Fiber strands comprising a thermoplastic material are placed on a cylindrical surface and heated such that they soften and become malleable. The fiber strands assume the curvature of the cylindrical surface and, upon cooling below their softening temperature, retain the curvature. The curved-fiber strands are then cut to a desired length.

1 . (canceled) 
     
     
         2 . (canceled) 
     
     
         3 . A method of preparing curved fibers, using the apparatus of  claim 3 , comprising;
 i. selecting a cylindrical screw feeder whose diameter between the threads provides a desired curvature;   ii. selecting one or more continuous fiber strands, the fibers having a composition with a workability-temperature range;   iii. threading the fiber strands through the opposing wheels in the rolling zone, and wrapping the strands onto the entire length of the screw feeder between the threads toward the unrolling zone;   iv. guiding the fiber strands off of the screw feeder and threading them through the opposing wheels in the unrolling zone;   v. initiating rotation of the screw feeder;   vi. activating a heat source in the heating zone, such that the fiber composition passing through the heating zone reaches a temperature within its workability-temperature range;   vii. cooling the fiber strands in the cooling zone such that the fiber composition is restored to a temperature below its softening temperature;   viii. cutting the fiber strands into desired lengths.   
     
     
         4 . The method of  claim 3 , wherein the fiber diameter is up to 300 micrometers. 
     
     
         5 . The method of  claim 3 , wherein the curved-fiber length after cutting is between about 5 mm and 50 mm. 
     
     
         6 . The method of  claim 3 , wherein the Feret length of the curved fibers after cutting is between about 5 mm and 30 mm. 
     
     
         7 . The method of  claim 3 , wherein the curvature radius of the fibers after cutting is between about 5 mm and 50 mm. 
     
     
         8 . The method of  claim 3 , wherein the fiber composition comprises a thermoplastic material. 
     
     
         9 . The method of  claim 3 , wherein the fiber composition comprises one or more members of the list comprising: acrylonitrile butadiene styrene, cellulose acetate, cycloolefin copolymer, ethylene-vinyl acetate, ethylene-vinyl alcohol, acrylic/PVC alloy, polyacetal, polyacrylate, polyacrylonitrile, polyamide, polyamide-imide, polyaryletherketone, polybutadiene, polybutylene, polybutylene terephthalate, polycaprolactone, polychlorotrifluoroethylene, polyethylene terephthalate, polycyclohexone dimethylene terepthlalate, polycarbonate, polyhydroxyalkanoate, polyketone, polyester, polyethylene, polyetheretherketoneketone, polyetherimide, polyethersulfone, polyethylenechlorinate, polyimide, polylactic acid, polymethylpentene, polyolefins, polyphenylene oxide, polyphenylene sulfide, polyphtalamide, polypropylene, polystyrene, polysulfone, polytrimethylene terephthalate, polyurethane, polyvinyl acetate, polyvinyl chloride and styrene-acrylonitrile. 
     
     
         10 . A method of treating a subterranean well, comprising the use of one or more fluids chosen from drilling fluids, cement slurries, spacer fluids, chemical washes, completion fluids, acidizing fluids, fracturing fluids and gravel-pack fluids, wherein said fluids comprise curved fibers obtained by the method of  claim 3 .