Strong Nonwoven Fabrics for Use in Silt Control Systems

Abstract

Strong nonwoven fabrics can be used as a sheet in a silt screen fence or other temporary silt screen barrier. The fabrics can be without reinforcements. Enhanced features of these strong nonwoven fabrics can enable them to be used as a sheet in a silt screen fence or other temporary silt screen barrier without adding additional processing steps. A strong nonwoven fabric without internal or external reinforcement that does not tear easily and has excellent light stability can be used.

What is claimed is: 
     
         1 . A containment system, comprising a nonwoven fabric having no reinforcement, wherein the nonwoven fabric has an average filter efficiency of at least 93% as measured by ASTM D5141, and a tensile strength of at least 20 pounds force (lb f ) as measured by ASTM D4632. 
     
     
         2 . The containment system according to  claim 1 , wherein the nonwoven fabric is adapted to separate oil from an oil and water emulsion. 
     
     
         3 . The containment system according to  claim 1 , wherein the nonwoven fabric is adapted to separate at least 95% of 320 centipoise (cp) oil from an oil and water emulsion that contains about 4.5% of 320 cp oil as measured according to test method 1664A HEM (n-Hexane Extractable Material) (Oil and Grease). 
     
     
         4 . The containment system according to  claim 1 , wherein the nonwoven fabric comprises nylon, polyester, polypropylene, or a combination thereof. 
     
     
         5 . The containment system according to  claim 1 , wherein the nonwoven fabric comprises nylon 6 or nylon 6,6. 
     
     
         6 . The containment system according to  claim 1 , wherein the nonwoven fabric comprises an engraved pattern. 
     
     
         7 . The containment system according to  claim 1 , wherein the nonwoven fabric is a bonded nonwoven fabric and_comprises a bond area of 17% to 25% of the nonwoven fabric. 
     
     
         8 . The containment system according to  claim 1 , wherein the nonwoven fabric has a filter efficiency of at least 93% for a flux rate of at least 0.9 gallons per minute per square foot as measured by ASTM D5141. 
     
     
         9 . The containment system according to  claim 1 , wherein the nonwoven fabric has a basis weight in a range of from 1 ounce per square yard (osy) to 12 osy,
 wherein the nonwoven fabric has an air permeability of no more than 250 cubic feet per minute per square foot (ft 3 /minute/ft 2 ), and   wherein the nonwoven fabric has a thickness of at least 18 mils and a fabric density of at least 0.18 grams per cubic centimeter (g/cc).   
     
     
         10 . The containment system according to  claim 1 , wherein the nonwoven fabric has a mean pore size of no more than 65 microns. 
     
     
         11 . The containment system according to  claim 1 , wherein the nonwoven fabric comprises a UV stabilizer, and wherein the nonwoven fabric is adapted to have, after 500 hours of exposure to a xenon light source and water spray according to the protocol described in ASTM D5534 07, a machine direction grab tensile strength of at least 44 lb f  as measured by ASTM D5034, a cross direction grab tensile strength of at least 33 lb f  as measured by ASTM D5034, a machine direction grab elongation of at least 42% as measured by ASTM D5034, and a cross direction grab elongation of at least 56% as measured by ASTM D5034. 
     
     
         12 . The containment system according to  claim 11 , wherein the nonwoven fabric has an orange shade that is at least as dark as a Pantone 472C after 500 hours of exposure to a xenon light source and water spray according to the protocol described in ASTM D4355 07. 
     
     
         13 . The containment system according to  claim 1 , further comprising a post to which the nonwoven fabric is attached. 
     
     
         14 . The containment system according to  claim 13 , wherein the nonwoven fabric passes the criteria for United States Environmental Protection Agency (EPA) SW-846, Third Edition. 
     
     
         15 . The containment system according to  claim 13 , wherein the nonwoven fabric passes the criteria for NSF/ANSI Standard 61-2007a. 
     
     
         16 . The containment system according to  claim 2 , further comprising a post to which the nonwoven fabric is attached. 
     
     
         17 . The containment system according to  claim 16 , wherein the nonwoven fabric passes the criteria for United States Environmental Protection Agency (EPA) SW-846, Third Edition. 
     
     
         18 . The containment system according to  claim 16 , wherein the nonwoven fabric passes the criteria for NSF/ANSI Standard 61-2007a. 
     
     
         19 . A method of fabricating a containment system, comprising:
 forming a nonwoven fabric; and   attaching the nonwoven fabric to a supporting structure to form the containment system,   wherein forming the nonwoven fabric comprises:
 forming, in an extruder, a master batch comprising at least one polymer;
 extruding the master batch in the form of a plurality of filaments, 
 depositing the filaments onto a collection surface to form a web, and 
 thermally bonding the filaments of the web to form the nonwoven fabric, 
 
 wherein the nonwoven fabric has an average filter efficiency of at least 93% as measured by ASTM D5141, and a tensile strength of at least about 20 lb f  as measured by ASTM D4632. 
   
     
     
         20 . The method according to  claim 19 , wherein the nonwoven fabric is adapted to separate oil from an oil and water emulsion. 
     
     
         21 . The containment system according to  claim 2 , wherein the oil is crude oil.