Pressureless cure system for chemically cross-linking ethylene containing polymers, to form an insulated conductor

Claim 1

A method of making an electric cable having a cured relatively dense and substantially non-porous insulating composition about a conductor comprising ethylene containing polymer and mineral filler cured at substantially atmospheric pressure, comprising the steps of: treating a mineral filler with tetramethyltetravinylcyclotetrasiloxane by admixing said mineral filler with about 0.15 to 4.0 percent of tetramethyltetravinylcyclotetrasiloxane by weight of the filler, and preparing the insulating composition by admixing the ingredients comprising an ethylene containing polymer, said mineral filler and treating tetramethyltetravinylcyclotetrasiloxane, and curing agent; forming the insulation of admixed composition about a conductor; and thereafter heating the said formed insulation of the admixed composition at about atmospheric pressure in a non-aqueous heat transfer medium to a temperature and for a dwell time sufficient to effect an in situ cross-linking cure of the ethylene containing polymer to a relatively dense and substantially non-porous insulation of filled polymeric composition.

Claim 2

A method of making an electric cable having a cured relatively dense and substantially non-porous insulating composition about a conductor comprising ethylene containing polymer and mineral filler cured at substantially atmospheric pressure, comprising the steps of: treating a mineral filler with tetramethyltetravinylcyclotetrasiloxane by admixing said mineral filler with about 0.15 to 4.0 percent of tetramethyltetravinylcyclotetrasiloxane by weight of the filler, and preparing the insulating composition by admixing the ingredients comprising an ethylene containing polymer, said mineral filler and treating tetramethyltetravinylcyclotetrasiloxane, and curing agent; forming the insulation of admixed composition about a conductor; and thereafter heating the said formed insulation of the admixed composition at about atmospheric pressure in a non-aqueous heat transfer medium to a temperature and for a dwell time sufficient to effect an in situ cross-linking cure of the ethylene containing polymer to a relatively dense and substantially non-porous insulation of filled polymeric composition.

Claim 3

A method of making an electrical cable having a cured substantially non-porous insulating composition about a conductor comprising ethylene containing polymer and mineral filler cured at substantially atmospheric pressure, comprising the steps of: treating a mineral filler selected from the group consisting of aluminum silicate, aluminum oxide, calcium silicate, silica, magnesium silicate, titanium dioxide, and mixtures thereof, with tetramethyltetravinylcyclotetrasiloxane by admixing said mineral filler with about 0.15 to 4.0 percent of tetramethyltetravinylcyclotetrasiloxane by weight of the filler, and preparing the insulating composition by admixing the ingredients comprising an ethylene containing polymer with at least about 50 mole percent ethylene selected from the group consisting of polyethylene, copolymers of ethylene and propylene, and copolymers of ethylene and vinyl acetate, and mixtures thereof with about 25 to 60 percent by weight of the composition of said mineral filler treated with tetramethyltetravinylcyclotetrasiloxane and about 0.5 to 10 parts by weight of organic peroxide curing agent per 100 parts by weight of ethylene containing polymer; forming the insulation of admixed composition about a conductor; and thereafter heating the said formed insulation of the admixed composition at about atmospheric pressure in a non-aqueous heat transfer medium to a temperature and for a dwell time sufficient to effect an in situ cross-linking cure of the ethylene-containing polymer to a relatively dense and substantially non-porous insulation of filled polymeric composition.

Claim 4

A method of making an electrical cable having a cured substantially non-porous insulating composition about a conductor comprising ethylene containing polymer and mineral filler cured at substantially atmospheric pressure, comprising the steps of: treating a mineral filler selected from the group consisting of aluminum silicate, aluminum oxide, calcium silicate, silica, magnesium silicate, titanium dioxide, and mixtures thereof, with tetramethyltetravinylcyclotetrasiloxane by admixing said mineral filler with about 0.15 to 4.0 percent of tetramethyltetravinylcyclotetrasiloxane by weight of the filler, and preparing the insulating composition by admixing the ingredients comprising an ethylene containing polymer with at least about 50 mole percent ethylene selected from the group consisting of polyethylene, copolymers of ethylene and propylene, and copolymers of ethylene and vinyl acetate, and mixtures thereof with about 25 to 60 percent by weight of the composition of said mineral filler treated with tetramethyltetravinylcyclotetrasiloxane and about 0.5 to 10 parts by weight of organic peroxide curing agent per 100 parts by weight of ethylene containing polymer; forming the insulation of admixed composition about a conductor; and thereafter heating the said formed insulation of the admixed composition at about atmospheric pressure in a non-aqueous heat transfer medium to a temperature and for a dwell time sufficient to effect an in situ cross-linking cure of the ethylene-containing polymer to a relatively dense and substantially non-porous insulation of filled polymeric composition.