Filling materials for electrical and light waveguide communications cables

Claim 1

A composition of matter composed of a mixture consisting essentially of of a styrene block copolymer rubber, mineral oil, and inorganic hollow microspheres, wherein: (a) the amount and type of said block copolymer rubber is either: (i) 1 to 30 percent by weight of styrene-ethylene-butylene-styrene block copolymer having a styrene to rubber ratio of approximately 0.4 and a specific gravity of approximately 0.9; (ii) 7 to 10 percent by weight of styrene-butadiene-styrene block copolymer having a styrene to rubber ratio of approximately 0.39 and a specific gravity of approximately 0.94; and (iii) 8 to 12 percent by weight of styrene-isoprene-styrene block copolymer having a styrene to rubber ratio of approximately 0.16 and a specific gravity of approximately 0.92; (b) wherein said mineral oil is either: (i) 60 to 80 percent by weight of paraffinic mineral oil having a viscosity-gravity constant (ASTM D 2501-67) of approximately 0.78 to 0.85 with a minimum of 65 percent paraffinic carbon atoms and a maximum of 5 percent aromatic carbon atoms; or (ii) 60 to 80 percent by weight of naphthenic mineral oil having a viscosity-gravity constant (ASTM D 2501-67) of approximately 0.78 to 0.85 with a minimum of 35 percent naphthenic carbon atoms and a maximum of 5 percent aromatic carbon atoms; and (c) said inorganic hollow microspheres are either: (i) 1 to 20 percent by weight of inorganic hollow microspheres made from glass, having a particle diameter between 10 and 200 microns and a particle density range of approximately 0.1 to 0.3 g/cm 3 ; or (ii) up to 35 percent by weight of inorganic hollow microspheres made from ceramic materials, having a particle diameter between 60 and 325 microns and a particle density of approximately 0.6 g/cm 3 .