High tenacity polyolefin ropes having improved cyclic bend over sheave performance

Abstract

An improved rope is formed from high tenacity polyolefin fibers, such as extended chain polyethylene fibers. The fibers and/or the rope are coated with a composition comprising an amino functional silicone resin and a neutralized low molecular weight polyethylene. The ropes are useful in marine applications, such as in deep sea lifting. The ropes have improved cyclic bend over sheave fatigue resistance.

1 . A rope having improved cyclic bend over sheave (CBOS) fatigue resistance, said rope comprising high tenacity polyolefin fibers, said rope and/or said fibers being coated with a composition comprising an amino functional silicone resin and a neutralized low molecular weight polyethylene.  
   
   
       2 . The rope of  claim 1  wherein said high tenacity polyolefin fibers comprise extended chain polyethylene fibers.  
   
   
       3 . The rope of  claim 3  wherein said fibers have a tenacity of at least about 15 g/d.  
   
   
       4 . The rope of  claim 3  wherein said fibers have a tenacity of at least about 30 g/d.  
   
   
       5 . The rope of  claim 1  wherein said rope is formed from said fibers which are coated with said composition prior to forming said rope.  
   
   
       6 . The rope of  claim 1  wherein said rope is formed from said fibers and is thereafter coated with said composition.  
   
   
       7 . The rope of  claim 1  wherein said composition is present on said rope in an amount of at least about 5 weight percent based on the weight of said rope.  
   
   
       8 . The rope of  claim 1  wherein said low molecular weight polyethylene is the major component of said composition.  
   
   
       9 . The rope of  claim 1  wherein said low molecular weight polyethylene is present in an amount of from about 55 percent to about 85 percent by weight based on the total weight of said composition.  
   
   
       10 . The rope of  claim 9  wherein said low molecular weight polyethylene is fully neutralized.  
   
   
       11 . The rope of  claim 1  wherein said rope is a braided rope.  
   
   
       12 . The rope of  claim 2  wherein said composition consists essentially of said extended chain polyethylene fibers.  
   
   
       13 . A rope having improved cyclic bend over sheave (CBOS) fatigue resistance, said rope consisting essentially of high tenacity polyolefin fibers, said rope and/or said fibers being coated with a composition comprising an amino functional silicone resin and a neutralized low molecular weight polyethylene.  
   
   
       14 . The rope of  claim 13  wherein said high tenacity polyolefin fibers comprise extended chain polyethylene fibers.  
   
   
       15 . The rope of  claim 14  wherein said fibers have a tenacity of at least about 30 g/d.  
   
   
       16 . The rope of  claim 13  wherein said composition is present on said rope in an amount of from about 10 to about 25 weight percent based on the weight of said rope.  
   
   
       17 . The rope of  claim 16  wherein said low molecular weight polyethylene is present in an amount of from about 55 percent to about 85 percent by weight based on the total weight of said composition.  
   
   
       18 . A method of improving the cyclic bend over sheave (CBOS) fatigue life of a rope comprising high tenacity polyolefin fibers, said method comprising coating said rope and/or said fibers forming said rope with a composition comprising an amino functional silicone resin and a neutralized low molecular weight polyethylene.  
   
   
       19 . The method of  claim 18  wherein said rope comprises extended chain polyethylene fibers.  
   
   
       20 . The method of  claim 18  wherein said rope consists essentially of extended chain polyethylene fibers.  
   
   
       21 . The method of  claim 18  wherein said low molecular weight polyethylene is present in an amount of from about 55 percent to about 85 percent by weight based on the total weight of said composition.  
   
   
       22 . The method of  claim 21  wherein said coating composition has a solids content of at least about 25% by weight.  
   
   
       23 . The method of  claim 21  wherein said coating composition has a solids content of at least about 30% by weight.  
   
   
       24 . The method of  claim 23  wherein said amino functional silicone resin is in the form of an emulsion having a pH of from about 9 to about 11.  
   
   
       25 . The method of  claim 24  wherein said low molecular weight polyethylene has a molecular weight of from about 300 to about 3000 Dalton, and is in the form of an emulsion.  
   
   
       26 . In a method of lifting and placing heavy objects from and onto a seabed using a synthetic fiber rope, the improvement comprising utilizing as said rope a rope comprising high tenacity polyolefin fibers, said rope and/or said fibers being coated with a composition comprising an amino functional silicone resin and a neutralized low molecular weight polyethylene.  
   
   
       27 . The method of  claim 26  wherein said fibers comprise extended chain polyethylene fibers.  
   
   
       28 . The method of  claim 27  wherein said fibers consist essentially of extended chain polyethylene fibers.  
   
   
       29 . The method of  claim 27  including coating said composition onto said rope and/or said fibers to provide said composition on said rope in an amount of from about 10 to about 25 weight percent based on the weight of said rope.  
   
   
       30 . The method of  claim 29  wherein said low molecular weight polyethylene is present in an amount of from about 55 percent to about 85 percent by weight based on the total weight of said composition.