Power transmission belt

Abstract

An endless power transmission belt having a load carrier cord formed from a plurality of strands, wherein the strands include fibers of para-aramid and polyvinylpyrrolidone (PVP); and a method for increasing the flexural fatigue resistance and durability of an endless belt, including the step of selecting for the belt's load carrier cord a yarn comprising a fiber of para-aramid and PVP. The belt may be of cast polyurethane.

1 . An endless belt comprising an elastomeric main belt body portion and a sheave contact portion and having a load carrier cord embedded in said belt body portion, said cord comprising a plurality of fibers comprising para-aramid and polyvinylpyrrolidone; said fibers comprising from about 7% to about 20% by weight of polyvinylpyrrolidone based on the total weight of said para-aramid.  
   
   
       2 . The endless belt of  claim 1  wherein said para-aramid is poly(p-phenylene terephthalamide).  
   
   
       3 . The endless belt of  claim 2  wherein said fibers consist essentially of said poly(p-phenylene terephthalamide) and said polyvinylpyrrolidone.  
   
   
       4 . The endless belt of  claim 1  wherein said main body portion comprises polyurethane elastomer.  
   
   
       5 . The endless belt of  claim 4  wherein said polyurethane elastomer is cast, and wherein said cord further comprises an adhesive treatment consisting of at most a primer.  
   
   
       6 . The endless belt of  claim 5  wherein said adhesive treatment consists of a primer.  
   
   
       7 . The endless belt of  claim 5  wherein said fibers comprise up to about 13% by weight of polyvinylpyrrolidone based on the total weight of said para-aramid.  
   
   
       8 . The endless belt of  claim 5  selected from a multi-V-ribbed belt, a V-belt and a toothed belt.  
   
   
       9 . An endless power transmission belt comprising a cast polyurethane elastomeric main belt body and a tensile section aligned along the length of the belt, said tensile section comprising at least one load carrying cord, and characterized in that said load carrying cord comprises a plurality of fibers consisting essentially of poly(p-phenylene terephthalamide) and polyvinylpyrrolidone, said polyvinylpyrrolidone being present in said fibers in an amount within the range of from about 7% to about 20% by weight based on the total weight of poly(p-phenylene terephthalamide); said cord further comprising an adhesive treatment consisting of at most a primer.  
   
   
       10 . A method for increasing the flexural fatigue resistance and durability of a power transmission belt comprising a belt body portion and a para-aramid load carrier cord embedded in said belt body portion; comprising: 
 selecting for the belt's load carrier cord a yarn comprising a fiber of para-aramid and polyvinylpyrrolidone; and    selecting for the fiber composition a concentration of polyvinylpyrrolidone from about 7% to about 20% by weight based on the total weight of para-aramid.    
   
   
       11 . The method of  claim 10  wherein said para-aramid is poly-p-phenylene terephthalamide.  
   
   
       12 . The method of  claim 10  further comprising: 
 combining a plurality of said yarns to form said load carrier cord.    
   
   
       13 . The method of  claim 12  wherein said combining comprises twisting together said yarns.  
   
   
       14 . The method of  claim 13  wherein said combining comprises: 
 first twisting strands comprising one or more said yarns; and    second twisting together one or more said strands in the opposite direction of said first twisting.    
   
   
       15 . The method of  claim 14  further comprising one or more selected from: 
 first treating said cord with a primer;    second treating said cord with an adhesive;    third treating said cord with an overcoat or rubber cement.    
   
   
       16 . The method of  claim 14  further comprising two or more selected from: 
 first treating said cord with a primer;    second treating said cord with an adhesive;    third treating said cord with an overcoat or rubber cement.    
   
   
       17 . The method of  claim 14  further comprising: 
 forming said belt body portion from cast polyurethane elastomer; and    treating said cord only with a primer or not at all.