Low cost, high performance, flexible, water-swellable reinforcement for communications cable

Abstract

A low cost, high performance, water-swellable, flexible reinforcement member that can be used for both optical and copper communications cable. The water-swellable reinforcement members made according to the preferred process are more rigid than known reinforcement members, but are less rigid than glass pultruded rods. Communications cables utilizing these members are lightweight, water-swellable and exhibit an improved combination of strength and flexibility compared to traditional communications cables. Further, these communication cables may then be installed into underground ducts using more economical and faster installation techniques.

1 - 19 . (canceled) 
     
     
         20 . A method for forming a flexible reinforcement member for use in a communications cable, the method comprising:
 providing a high modulus fiber material, said fiber material selected from the group consisting of a plurality of sized or unsized aramid fibers and a plurality of sized or unsized poly(p-phenylene-2,6-benzobisoxazole) (PBO) fibers, sized or unsized carbon fibers or sized or unsized high tenacity, linearized polyethylene fiber, and a plurality of sized or unsized high silica glass fibers;   coating said fiber material with a low molecular weight primary saturant, said low molecular weight primary saturant having a melting point below approximately 300 degrees Celsius and a melt viscosity of less than approximately 1000 centipoise, wherein the weight of said low molecular weight primary saturant on said fiber material comprises between 0.1 and 35 percent of the flexible reinforcement member;   coating said fiber material with a higher molecular weight water-swellable polymer topcoat.   
     
     
         21 . The method of  claim 20 , further comprising introducing a low molecular weight primary saturant to an application device. 
     
     
         22 . The method of  claim 21 , wherein introducing a low molecular weight primary saturant to an application device comprises introducing a low molecular weight primary saturant to an immersion bath. 
     
     
         23 . The method of  claim 21 , further comprising introducing a high molecular weight water-swellable, polymer topcoat onto said low molecular weight primary saturant. 
     
     
         24 . The method of  claim 23 , wherein introducing said fiber material to said application device and introducing a high molecular weight polymer topcoat onto said primary saturant comprises:
 introducing a low molecular weight primary saturant to a first application device;   melting said low molecular weight primary saturant within said first application device at a temperature sufficient to maintain said low molecular weight primary saturant at a viscosity of less than about 1000 centipoise;   introducing said fiber material to said first application device to coat said low molecular weight primary saturant onto said fiber material to form a coated member;   removing said coated member from said first application device;   introducing said coated member to a stripper die to remove an excess of said low molecular weight primary saturant from said fiber material;   introducing said coated member to a high molecular weight water-swellable topcoat material contained within second application device to form a topcoated member;   removing said topcoated member from said second application device;   introducing said topcoated member to a second stripper die to remove an excess of said high molecular weight topcoat material from said topcoated member; and   cooling said topcoated member to form the flexible reinforcement member, wherein the weight of said low molecular weight primary saturant on said fiber material comprises between 10 and 35 percent of the flexible reinforcement member and wherein the weight of said high molecular topcoat material comprises between approximately 1 and 25 percent of the flexible reinforcement member.   
     
     
         25 . The method of  claim 20 , wherein introducing a low molecular weight primary saturant to a first application device and introducing said coated member to a high molecular weight water-swellable topcoated member contained within a second application device comprises:
 introducing a low molecular weight primary saturant to first application device, said primary saturant comprising a low molecular weight mineral wax selected from the group consisting of a low molecular weight microcrystalline wax, a low molecular weight polyalphaolefin wax, a low molecular weight polyethylene wax, a low molecular weight polyethylene wax, a low molecular weight maleated polypropylene polymer and blends thereof; and   introducing said coated member to a high molecular weight water-swellable topcoat material contained within second application device to form a topcoated member, said high molecular weight topcoated material selected from the group consisting of ethylene vinyl acetate (EVA) polymers, block copolymers of polybutylene terephalate, copolymers of long chain polyether glycols, thermoplastic elastomers, olefins, urethanes, polypropylene, polyethylene, polyurethane, low molecular weight mineral wax, polyacrylamides and blends thereof.   
     
     
         26 . A method for forming a flexible reinforcement member for use in a communications cable, the method comprising:
 providing a high modulus fiber material, said fiber material selected from the group consisting of a plurality of sized or unsized aramid fibers and a plurality of sized or unsized poly(p-phenylene-2,6-benzobisoxazole) (PBO) fibers, sized or unsized carbon fibers or sized or unsized high tenacity, linearized polyethylene fiber, and a plurality of sized or unsized high silica glass fibers wherein said high modulus fiber material is pre-coated with a higher molecular weight water-swellable polymer topcoat; and   coating said fiber material with a low molecular weight primary saturant, said low molecular weight primary saturant having a melting point below approximately 300 degrees Celsius and a melt viscosity of less than approximately 1000 centipoise, wherein the weight of said low molecular weight primary saturant on said fiber material comprises between 0.1 and 35 percent of the flexible reinforcement member.   
     
     
         27 . The method of  claim 26 , wherein introducing a low molecular weight primary saturant to an application device comprises introducing a low molecular weight primary saturant to an application device, said low molecular weight primary saturant comprising a blend of a low molecular weight microcrystalline wax and a styrene butadiene rubber material, wherein said blend is between approximately 0.1 and 99.9 percent by weight of said low molecular weight microcrystalline wax and between approximately 0.1 and 99.9 percent by weight of said styrene butadiene rubber. 
     
     
         28 . The method of  claim 27 , wherein introducing a low molecular weight primary saturant to an application device comprises introducing a low molecular weight primary saturant to an immersion bath. 
     
     
         29 . The method of  claim 28 , wherein the water absorbency for the reinforcement member is between about 349 to about 438 percent by weight. 
     
     
         30 . The method of  claim 28 , wherein said high modulus fiber material is pre-coated with a high molecular weight, water-swellable polymer topcoat selected from the group consisting of ethylene vinyl acetate (EVA) polymers, block copolymers of polybutylene terephalate, copolymers of long chain polyether glycols, thermoplastic elastomers, olefins, urethanes, polypropylene, polyethylene, polyurethane, low molecular weight mineral wax, polyacrylamides and blends thereof. 
     
     
         31 . The method of  claim 20 , further comprising introducing said low molecular weight primary saturant to an application device, said low molecular weight primary saturant comprising a blend of a low molecular weight wax and a higher molecular weight, higher viscosity thermoplastic or thermoplastic elastomeric material, wherein said blend is between approximately 0.1 and 99.9 percent by weight of said low molecular weight wax and between approximately 0.1 and 99.9 percent by weight of said styrene butadiene rubber. 
     
     
         32 . The method of  claim 31 , wherein said higher molecular weight, higher viscosity thermoplastic or thermoplastic elastomeric material comprises styrene butadiene rubber. 
     
     
         33 . The method of  claim 31 , wherein said blend of a low molecular weight wax and a higher molecular weight, higher viscosity thermoplastic or thermoplastic elastomeric material comprises between at least about 10 percent by weight to about 90 percent by weight of said low molecular weight wax and between at least about 10 percent by weight and about 90 percent by weight of said higher molecular weight, higher viscosity thermoplastic or thermoplastic elastomeric material.