Buffer tubes with improved flexibility

Abstract

The present invention provides a communication cable buffer tube having a flexural modulus ranging from about 180 kpsi to about 280 kpsi.

1 . A buffer tube for a communication cable, the buffer tube comprising a polymer mixture with a flexural modulus ranging from about 180 to about 380 kpsi.  
   
   
       2 . The buffer tube of  claim 1 , wherein the flexural modulus ranges from about 180 kpsi to about 280 kpsi.  
   
   
       3 . A buffer tube for a communication cable, the buffer tube comprising a polymer mixture comprising an ethylene-ester copolymer, an ester-acid terpolymer, or a combination thereof.  
   
   
       4 . The buffer tube of  claim 3 , wherein said polymer mixture also comprises a base polymer, wherein the base polymer is PBT, PET, PC, or a combination thereof.  
   
   
       5 . The buffer tube of  claim 4 , wherein said base polymer comprises about 50 to about 95 volume percent of said polymer mixture, and wherein said ethylene-ester copolymer, ester-acid terpolymer, or combination thereof comprises from about 5 to about 50 volume percent of said polymer mixture.  
   
   
       6 . The buffer tube of  claim 5 , wherein said base polymer comprises about 75 to about 95 volume percent of said polymer mixture, and wherein said ethylene-ester copolymer, ester-acid terpolymer, or combination thereof comprises from about 5 to about 25 volume percent of said polymer mixture.  
   
   
       7 . A buffer tube for a communication cable, the buffer tube comprising a polymer mixture of a first polymer and a second polymer, wherein said second polymer has a flexural modulus significantly lower than the flexural modulus of said first polymer, and wherein the flexural modulus of said polymer mixture ranges from about 180 kpsi to about 280 kpsi.  
   
   
       8 . The tube of  claim 7 , wherein the flexural modulus of said first polymer is at least 360 kpsi.  
   
   
       9 . The tube of  claim 7 , wherein said first polymer is polypropylene, polyethylene, a copolymer of polypropylene and polyethylene, a nucleated copolymer of polypropylene and polyethylene, PBT, PET, PC, a polyamide, or a combination thereof.  
   
   
       10 . The tube of  claim 7 , wherein said second polymer is a low flexural modulus polyester, an ethylene-ester copolymer, an ester-acid terpolymer, or a combination thereof.  
   
   
       11 . The tube of  claim 10 , wherein said low flexural modulus polyester is polyvinyl acetate, a polyurethane, a modified polyester, a co-polyester-ether, other co-polyester, or a combination thereof.  
   
   
       12 . The tube of  claim 10 , wherein said ethylene-ester copolymer is EMA, EBA, EVA, or a combination thereof.  
   
   
       13 . The tube of  claim 10 , wherein said ester-acid terpolymer is EMAAA.  
   
   
       14 . A buffer tube for a communication cable, comprising a polymer mixture comprising PBT and EMA, EBA, EMAAA, or a combination thereof.  
   
   
       15 . The tube of  claim 14 , wherein said EMA comprises from about 20 to about 30 volume percent methyl acrylate, and wherein said EBA comprises from about 20 to about 30 volume percent butyl acrylate.  
   
   
       16 . The tube of  claim 14 , wherein the polymer mixture has a flexural modulus ranging from about 180 to about 380 kpsi.  
   
   
       17 . The tube of  claim 16 , wherein the flexural modulus ranges from about 180 to about 280 kpsi.  
   
   
       18 . The tube of  claim 14 , wherein the polymer mixture comprises about 50 to about 95 volume percent PBT and about 5 to about 50 volume percent EMA, EBA, EMAAA, or a combination thereof.  
   
   
       19 . The tube of  claim 18 , wherein the polymer mixture comprises about 75 to about 95 volume percent PBT and about 5 to about 25 volume percent EMA, EBA, EMAAA, or combination thereof.  
   
   
       20 . A communication cable comprising a buffer tube, the buffer tube comprising a polymer mixture with a flexural modulus ranging from about 180 to about 380 kpsi.  
   
   
       21 . The cable of  claim 20 , wherein the flexural modulus ranges from about 180 kpsi to about 280 kpsi.  
   
   
       22 . A communication cable containing a buffer tube, the buffer tube comprising a polymer mixture comprising an ethylene-ester copolymer, an ester-acid terpolymer, or a combination thereof.  
   
   
       23 . The cable of  claim 22 , also comprising PBT.  
   
   
       24 . The cable of  claim 23 , wherein said PBT comprises about 50 to about 95 volume percent of said polymer mixture, and wherein said ethylene-ester copolymer, ester-acid terpolymer, or combination thereof comprises about 5 to about 50 volume percent of said polymer mixture.  
   
   
       25 . The cable of  claim 24 , wherein said PBT comprises about 75 to about 95 volume percent of said polymer mixture, and wherein said ethylene-ester copolymer, ester-acid terpolymer, or combination thereof comprises about to about 25 volume percent of said polymer mixture.  
   
   
       26 . A communications cable, the cable containing a buffer tube comprising a polymer mixture of PBT and EMA, EBA, EMAAA, or a combination thereof.  
   
   
       27 . The cable of  claim 26 , wherein said polymer mixture comprises about 50 to about 95 volume percent PBT and about 5 to about 50 volume percent EMA, EBA, EMAAA, or combination thereof.  
   
   
       28 . A communications system containing a cable, the cable containing a buffer tube comprising a polymer mixture of PBT and EMA, EBA, EMAAA, or a combination thereof.  
   
   
       29 . The system of  claim 28 , wherein the polymer mixture has a flexural modulus ranging from about 180 to about 380 kpsi.  
   
   
       30 . The system of  claim 25 , wherein the polymer mixture has a flexural modulus ranging from about 180 to about 280 kpsi.  
   
   
       31 . The system of  claim 28 , wherein the polymer mixture comprises about 50 to about 95 volume percent PBT and about 5 to about 50 volume percent EMA, EBA, EMAAA, or combination thereof.  
   
   
       32 . A method of making a buffer tube for a communication cable, comprising: 
 providing a polymer mixture containing a base polymer and an ethylene-ester copolymer;    melting the polymer mixture; and    extruding the melted polymer mixture.    
   
   
       33 . The method of  claim 32 , wherein said base polymer is PBT, PET, PC, or a combination thereof.  
   
   
       34 . A method for reducing the flexural modulus of PBT, PET, PC, or a combination thereof, comprising adding a low flexural modulus polymer to PBT, PET, PC, or the combination thereof.  
   
   
       35 . The method of  claim 34 , wherein said low flexural modulus polymer is a low flexural modulus polyester, an ethylene-ester copolymer, an ester-acid terpolymer, or a combination thereof.  
   
   
       36 . The method of  claim 35 , wherein said ester-acid terpolymer is EMAAA.  
   
   
       37 . The method of  claim 35 , wherein said low flexural modulus polyester is polyvinyl acetate, a polyurethane, a modified polyester, a copolyester-ether, other co-polyester, or a combination thereof.  
   
   
       38 . The method of  claim 35 , wherein said ethylene-ester copolymer is EMA, EBA, EVA, or a combination thereof.  
   
   
       39 . The method of  claim 38 , wherein said PBT, PET, PC, or combination thereof comprises from about 5 to about 50 percent by volume EMA, EBA, EVA or a combination thereof.  
   
   
       40 . A method for communicating, comprising: 
 providing a cable with a buffer tube comprising a polymer mixture of PBT, PET, PC, or a combination thereof, and EMA, EBA, EVA, EMAAA or a combination thereof; and    transmitting a signal over the cable.