Belden Wire & Cable Company

Other

Douglas D O'Brien

Robert David Kenny

Harry Lewis Nelson

Thomas L Rodeghero

The present invention relates to a flat-type communication cable for carrying frequencies in excess of 4 Mhz. The cable has a plurality of longitudinally extending conductor passageways positioned side-by-side and preferably at least four passageways such that there are two end longitudinal passageways and a plurality of side-by-side intermediate passageways. Each passageway has a longitudinally extending opening which opens to an adjacent passageway. There are twisted pair conductors loosely located in each of the passageways with not more than one twisted pair conductor being in each passageway. Each twisted pair conductor has a cross-sectional envelope area less than a cross-sectional envelope area of the passageway in which the twisted pair is contained.

Flat-type communication cable

A plenum cable having a plurality of twisted pair conductors with at least one pair having a non-fluorinated polyolefin insulation and all of the twisted pair conductors which are adjacent to each other having a lay length of about 0.4 to 4' with the preferred lay length being 0.4 to 1.25 inches. The lay length of the non-fluorinated polyolefin twisted pair conductor is preferably 1.0 to 1.25 inches and the lay lengths of the fluorinated polyolefin twisted pair conductors is preferably 0.5 to 85'. The twisted pair conductor insulation is preferably radially joined along the entire length thereof. Preferably, the twisted pair conductors all have an impedance of 90 to 110 ohms and the impedance does not vary by more or less than .+-.0.05 of an average impedance. Also, the twisted pair conductors preferably have a center-to-center distance that does not vary by more or less than .+-.0.03 of an average center-to-center distance. Also, for another embodiment, all the adjacent twisted pair conductors have a dielectric constant within .+-.0.25 of each other.

Plenum cable

A plenum cable having a plurality of twisted pair conductors enclosed by a jacket. A plurality of the twisted pair conductors has one insulating material thereon and at least one twisted pair conductor has a different insulation material thereon. In the preferred structure at least one twisted-pair conductor has flame retardant polyethylene or flame retardant polypropylene insulation and at least one other twisted pair conductor being insulated with fluorinated ethylene propylene, tetrafluoroethylene, or ethylenechloro-trifluoroethylene. The preferred twisted pair conductors have a center-to-center distance along any point of a 1000 ft. twisted pair conductor that is .+-.0.3 of an average center-to-center distance and/or have an impedance of 90 to 110 ohms and a variation of .+-.0.05 when measured at 10 MHz to 200 MHz from an average impedance and/or have their dielectric layers joined together along the length of the dielectric layers and having an adhesion strength between said dielectric layers of from about 0.1 to about 5 lbs. force.

An insulated conductor and the flame retardant insulation composition used in plenum cables. The insulation composition includes as a polyolefin blend from about 50 to 85 parts by weight of polypropylene, 10 to about 40 parts by weight of a very low density polyethylene and from about 5 to about 20 parts by weight of a high and/or low density polyethylene. To one hundred parts by weight of the polyolefin blend there is about 6 to about 20 parts by weight of a chlorinated flame retardant, from about 4 to about 12 parts by weight of a flame retardant intumescent, from about 20 to 60 parts by weight of a non-halogen flame retardant, from about 0.2 to about 1.0 parts by weight of hindered phenolic stabilizer; and from about 0.1 to about 0.4 parts by weight of additional stabilizers. One of the non-halogen flame retardants in the polyolefin composition, may be zinc borate which triggers polymer and flame retardant decomposition when the polyolefin composition is exposed to an igniting flame. Alternatives to zinc borate include zinc stearate, magnesium stearate, ammonium octamolybdate (AOM), or zinc stannate.

Flame retardant polyolefin wire insulations

A plenum cable having a plurality of insulated conductors enclosed by a jacket. Each of the insulated conductors or twisted-pair conductors has a dielectric constant that varies .+-.0.25 from any other insulated conductor or twisted-pair conductor. In the preferred structure at least one twisted-pair conductor has flame retardant polyethylene or flame retardant polypropylene insulation and at least one other twisted pair conductor being insulated with fluorinated ethylene propylene, tetrafluoroethylene, or ethylenechloro-trifluoroethylene.

A flame retarded composition for wire insulations that includes a polyethylene blend having a high density polyethylene, in an amount from about 50 to about 95 parts per hundred, and a very low density polyethylene, in an amount from about 5 to about 50 parts per hundred, a primary brominated flame retardant, in an amount from about 30 to about 40 parts per hundred, a secondary chlorinated flame retardant, in an amount from about 5 to about 15 parts per hundred, a first flame retarding synergist, in an amount from about 12 to 20 parts per hundred, a second flame retarding synergist, in an amount from about 7 to about 11 parts per hundred, a first hindered phenolic stabilizer, in an amount from about 0.05 to about 0.30 parts per hundred, and a second hundred phenolic stabilizer, in an amount from about 0 to about 0.30 parts per hundred, a polypropylene polymer in an amount from 2 to 10 parts per hundred. The polyethylene blend further comprising a low density polyethylene, in an amount from about 10 to about 50 parts per hundred.

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Richmond, IN, United States of America

Douglas D O'Brien