Low cost, high performance flexible reinforcement for communications cable

Abstract

A low cost, high performance flexible reinforcement member that can be used for both optical and copper communications cable. The 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 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.

What is claimed is:  
     
         1 . A flexible reinforcement member for a communications cable comprising: 
 a plurality of high modulus fibers;    a primary saturant coupled to said plurality of high modulus fibers, said primary saturant having a melting point below approximately 300 degrees Celsius and a melt viscosity of less than approximately 1000 centipoise.    
     
     
         2 . The flexible reinforcement member of  claim 1 , wherein said primary saturant has a melting point between about 100 to about 150 degrees Celsius and a melt viscosity of less than 500 centipoise.  
     
     
         3 . The flexible reinforcement member of  claim 1 , wherein said plurality of high modulus fibers comprises a plurality of sized high modulus fibers 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 and a plurality of sized or unsized carbon fibers and a plurality of sized or unsized high silica glass and sized or unsized high tenacity, linearized polyethylene fiber.  
     
     
         4 . The flexible reinforcement member of  claim 1 , wherein said plurality of high modulus fibers comprises a plurality of glass fiber strands.  
     
     
         5 . The flexible reinforcement member of  claim 4 , wherein said plurality of glass fiber strands comprises at least one glass fiber bundle, each of said at least one glass fiber bundle comprising a plurality of glass fiber filaments.  
     
     
         6 . The flexible reinforcement member of  claim 2 , wherein said plurality of glass fiber strands comprises a plurality of glass fiber filaments and at least one glass fiber bundle, each of said at least one glass fiber bundle comprising a plurality of glass fiber filaments.  
     
     
         7 . The flexible reinforcement member of  claim 1 , wherein said primary saturant comprises a low molecular weight mineral wax.  
     
     
         8 . The flexible reinforcement member of  claim 7 , wherein said low molecular weight mineral wax is selected from the group consisting of a low molecular weight microcrystalline wax, a low molecular weight polyalphaolefin wax, a low molecular weight polyethylene wax, or a modified (oxidized or maleated) polyolefin such as polyethylene or polypropylene, and blends thereof.  
     
     
         9 . The flexible reinforcement member of  claim 1 , wherein said primary saturant comprises a blend of a low molecular weight microcrystalline wax and a styrene butadiene rubber, 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.  
     
     
         10 . The flexible reinforcement of  claim 9 , wherein said blend comprises a 50/50 by weight blend of said low molecular weight microcrystalline wax and said styrene butadiene rubber.  
     
     
         11 . The flexible reinforcement member of  claim 4 , wherein said plurality of glass fiber strands comprises a plurality of sized glass fiber strands selected from the group consisting of a plurality of sized or unsized E-type glass fiber strands and a plurality of sized or unsized ECR-type glass fibers.  
     
     
         12 . The flexible reinforcement member of  claim 1  further comprising a higher molecular weight polymer topcoat coupled to said primary saturant.  
     
     
         13 . The flexible reinforcement member of  claim 12 , wherein said primary saturant comprises approximately 0.1 and 35 percent of the total weight of said flexible reinforcement member and wherein said high molecular weight polymer topcoat comprises between approximately 0.1 and 35 percent of the total weight of said flexible reinforcement member.  
     
     
         14 . The flexible reinforcement member of  claim 13 , wherein said primary saturant comprises approximately 5 and 20 percent of the total weight of said flexible reinforcement member and wherein said high molecular weight polymer topcoat comprises between approximately 5 and 20 percent of the total weight of said flexible reinforcement member.  
     
     
         15 . The flexible reinforcement member of  claim 13 , wherein said primary saturant comprises approximately 10 and 15 percent of the total weight of said flexible reinforcement member and wherein said high molecular weight polymer topcoat comprises between approximately 10 and 15 percent of the total weight of said flexible reinforcement member.  
     
     
         16 . The flexible reinforcement member of  claim 12 , wherein said high molecular weight polymer topcoat is selected from the group consisting of a high molecular weight polyethylene topcoat, a high molecular weight polypropylene topcoat, a high molecular weight ethylene acrylic acid topcoat, a high molecular weight polypropylene and polyethylene copolymer topcoat, an ethylene vinyl acetate copolymer topcoat, a styrene-butadiene-styrene topcoat, a polybutadiene terephthlate polyether glycol topcoat, polyamide, polyolefins and thermoplastic elastomers, and blends thereof.  
     
     
         17 . The flexible reinforcement of  claim 16 , wherein the glass transition temperature (Tg) of said flexible reinforcement is greater than about  40 ° C.  
     
     
         18 . The flexible reinforcement member of  claim 16  wherein the adhesion of glass to polyethylene is greater than about 46 pounds of force per 0.5 inches of embedded strand.  
     
     
         19 . The flexible reinforcement member of  claim 12 , wherein said high molecular weight polymer topcoat comprises an ethylene acrylic acid polymer topcoat.  
     
     
         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 and sized or unsized carbon fibers or sized or unsized high tenacity, linearized polyethylene fiber;    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.    
     
     
         21 . The method of  claim 20 , wherein coating said fiber material comprises: 
 introducing a low molecular weight primary saturant to an application device;    melting said low molecular weight primary saturant within said application device at a temperature sufficient to maintain said low molecular weight primary saturant at a viscosity of approximately less than about 1000 centipoise;    introducing said fiber material to said 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 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;    cooling said coated 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.    
     
     
         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 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.  
     
     
         23 . 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.  
     
     
         24 . The method of  claim 20  further comprising introducing a high molecular weight polymer topcoat onto said low molecular weight primary saturant.  
     
     
         25 . The method of  claim 24 , 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 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.    
     
     
         26 . The method of  claim 23 , wherein introducing a low molecular weight primary saturant to a first application device and introducing said coated member to a high molecular weight 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 topcoat material contained within second application device to form a topcoated member, said high molecular weight topcoated material selected from the group consisting of a high molecular weight polyethylene topcoat, a high molecular weight polypropylene topcoat, a high molecular weight ethylene acrylic acid topcoat, a high molecular weight polypropylene and polyethylene copolymer topcoat, an ethylene vinyl acetate copolymer topcoat, a styrene-butadiene-styrene topcoat, polyamide topcoat and a polybutadiene terephthlate polyether glycol topcoat and blends thereof.    
     
     
         27 . A method for improving strand integrity and decreasing water penetration and fiber-fiber abrasion in the high modulus fibers, in the form of strands and bundles, that comprise a flexible reinforcement material used in communications cables, the method comprising: 
 introducing a low molecular weight thermoplastic material to the high modulus fibers that penetrates the interstices of the fibers, wherein said low molecular weight thermoplastic material comprises between approximately 10 and 35 percent of the total weight of the flexible reinforcement material.    
     
     
         28 . The method of  claim 27 , wherein introducing a low molecular weight thermoplastic material comprises introducing a low molecular weight mineral wax to the high modulus fibers that penetrates the interstices of the high modulus fibers, wherein said low molecular weight mineral wax comprises between approximately 10 and 35 percent of the total weight of the flexible reinforcement material.  
     
     
         29 . The method of  claim 27 , wherein introducing a low molecular weight thermoplastic material comprises introducing a low molecular weight microcyrstalline wax to the high modulus fibers that penetrates the interstices of the high modulus fibers, wherein said low molecular weight microcrystalline wax comprises between approximately 10 and 35 percent of the total weight of the flexible reinforcement material.  
     
     
         30 . The method of  claim 27 , wherein introducing a low molecular weight thermoplastic material comprises introducing a blend of a low molecular weight mineral wax and a styrene butadiene rubber compound to the high modulus fibers that penetrates the interstices of the high modulus fibers, wherein said blend comprises between approximately 10 and 35 percent of the total weight of the flexible reinforcement material.