Multi-layer insulation system for electrical conductors

A multi-layer insulation system for electrical conductors, which comprises:

• (a) a fluoropolymer inner layer,
• wherein, the inner layer is formed by wrapping a fluoropolymer film, in an overlapping fashion, along a portion or length of an electrical conductor,
• (b) a polyimide middle layer, wherein the polyimide middle layer has a polyimide film, which has been coated with a sealable component and which is formed by wrapping the coated polyimide film, in an overlapping fashion, along a portion or length of the inner layer formed on the electrical conductor, and
• (c) an extruded, crosslinked fluoropolymer outer layer, wherein the fluoropolymer is selected from the group of copolymers and terpolymers of ethylene-tetrafluoroethylene, and mixtures thereof.

A multi-layer insulation system for electrical conductors, which comprises:

• (a) a polyimide inner layer, wherein the polyimide inner layer is formed by wrapping a polyimide film, which has been coated with a heat-sealable polyimide adhesive, in an overlapping fashion, along a portion or length of an electrical conductor,
• wherein, the polyimide film is substantially uniformly sealed to itself in overlapping regions along the length of the conductor, thereby forming an effective seal against moisture, and
• wherein, the polyimide inner layer demonstrates a high temperature (greater than or equal to 150° C.) adhesive bond strength (ASTM# 1876-00) of greater than 1000 grams per inch-width;
• and
• (b) an extruded, crosslinked fluoropolymer outer layer, wherein the fluoropolymer is selected from the group of copolymers and terpolymers of ethylene-tetrafluoroethylene, and mixtures thereof.

An insulated electrical conductor that comprises an electrical conductor and a multi-layer insulation system, wherein the multi-layer insulation system comprises:

• (a) a fluoropolymer inner layer,
• wherein, the inner layer is formed by wrapping a fluoropolymer film, in an overlapping fashion, along a portion or length of the conductor,
• (b) a polyimide middle layer, wherein the polyimide middle layer has a polyimide film, which has been coated with a sealable component and which is formed by wrapping the coated polyimide film, in an overlapping fashion, along a portion or length of the inner layer formed on the electrical conductor, and
• (c) an extruded, crosslinked fluoropolymer outer layer, wherein the fluoropolymer is selected from the group of copolymers and terpolymers of ethylene-tetrafluoroethylene, and mixtures thereof.

A process for preparing an insulated electrical conductor, which comprises:

• (a) forming a polvimide inner layer on an electrical conductor,
• wherein, the polyimide inner layer is formed by wrapping a polyimide film, which has been coated with a sealable component, in an overlapping fashion, along a portion or length of the electrical conductor, wherein the sealable component is selected from the group of perfluoropolymer, crosslinkable fluoropolymer and polyimide adhesives,
• (b) heating the polyimide film to a temperature ranging from about 240° to about 350° C. to cause overlapping regions of the coated film to bond, thereby forming an effective seal against moisture along the length of the conductor,
• wherein, the polyimide inner layer demonstrates a hiah temperature (greater than or equal to 150° C.) adhesive bond strength (ASTM# 1876-00) ranging from about 100 to about 250 grams per inch-width:
• and
• (c) forming a fluoropolyrner outer layer on the inner layer by extruding a fluoropolymer material along a portion or length of that layer;
• and
• (d) crosslinking the fluoropolymer outer layer, wherein, if the sealable component comprises a perfiuoropolymer, the fluoropolymer outer layer is crosslinked by exposing it to less than 60 megarads of radiation, with applied voltages ranging from about 50 to about 120 kilo volts.

A process for preparing an insulated electrical conductor, which comprises:

• (a) forming a fluoropolymer inner layer on an electrical conductor by wrapping a fluoropolymer film, in an overlapping fashion, along a portion or length of the electrical conductor,
• (b) forming a polyimide middle layer on the fluoropolymer inner layer by wrapping a polyimide film, which has been coated with a sealable component, in an overlapping fashion, along a portion or length of the fluoropolymer inner layer, wherein the sealable component is selected from the group of perfluoropolymer, crosslinked fluoropolymer and polyimide adhesives,
• (c) heating the polyimide film to a temperature ranging from about 240° to about 350° C. to cause overlapping regions of the film to bond, thereby forming an effective seal against moisture along the length of the conductor,
• (d) forming a fluoropolymer outer layer on the polyimide middle layer by extruding a fluoropolymer material along a portion or length of that layer, and
• (e) crosslinking the fluoropolymer outer layer, wherein, when the inner layer or the sealable component comprises a perfluoropolymer, the fluoropolymer outer layer is crosslinked by exposing it to less than 60 megarads of radiation, with applied voltages ranging from about 50 to about 120 kilo volts.

An insulated electrical conductor that comprises an electrical conductor and a multi-layer insulation system, wherein the multi-layer insulation system comprises:

• (a) a fluoropolymer inner layer,
• (b) a polyimide middle layer, and
• (c) an extruded, crosslinked fluoropolymer outer layer, wherein the fluoropolymer is selected from the group of copolymers and terpolymers of ethylene-tetrafluoroethylene, and mixtures thereof,
• wherein, the insulated electrical conductor is prepared by a process that comprises:
• (i) forming a fluoropolymer inner layer on an electrical conductor by wrapping a fluoropolymer film, in an overlapping fashion, along a portion or length of the conductor,
• (ii) forming a polyimide middle layer on the fluoropolymer inner layer by wrapping a polyimide film, which has been coated with a sealable component, in an overlapping fashion, along a portion or length of the fluoropolymer inner layer, wherein the sealable component is selected from the group of perfluoropolymer, crosslinked fluoropolymer and polyimide adhesives,
• (iii) heating the polyimide film to a temperature ranging from about 240° to about 350° C. to cause overlapping regions of the coated film to bond, thereby forming an effective seal against moisture along the length of the conductor,
• (iv) forming a fluoropolymer outer layer on the polyimide middle layer by extruding a fluoropolymer material along a portion or length of the middle layer, and
• (v) crosslinking the fluoropolymer outer layer, wherein, when the inner layer or the sealable component comprises a perfluoropolymer, the fluoropolymer outer layer is crosslinked by exposing it to less than 60 megarads of radiation, with applied voltages ranging from about 50 to about 120 kilo volts.

A multi-layer insulation system for electrical conductors, which comprises:

• (a) a polyimide inner layer, wherein the polyimide inner layer is formed by wrapping a polyimide film, which has been coated with a sealable component, in an overlapping fashion, along a portion or length of an electrical conductor,
• wherein, the polyimide film is substantially uniformly sealed to itself in overlapping regions along the length of the conductor, thereby forming an effective seal against moisture,
• wherein, the sealable component is selected from the group of perfluoropolymer, crosslinked fluoropolymer and polyimide adhesives, and
• wherein, the polyimide inner layer demonstrates a high temperature (greater than or egual to 150° C.) adhesive bond strength (ASTM# 1876-00) ranging from about 100 to about 250 grams per inch-width:
• and
• (b) an extruded, crosslinked fluoropolymer outer layer, wherein the fluoropolymer is selected from the group of copolymers and terpolymers of ethylene-tetrafluoroethylene, and mixtures thereof.

A process for preparing an insulated electrical conductor, which comprises:

• (a) forming a fluoropolymer inner layer on an electrical conductor by extruding a fluoropolymer material along a portion or length of the conductor,
• (b) forming a polyimide middle layer on the fluoropolymer inner layer by wrapping a polyimide film, which has been coated with a sealable component, in an overlapping fashion, along a portion or length of the fluoropolymer inner layer, wherein the sealable component is selected from the group, of perfluoropolymer, crosslinked fluoropolymer and polyimide adhesives,
• (c) heating the polyimide film to a temperature ranging from about 240° to about 350° C. to cause overlapping regions of the coated film to bond, thereby forming an effective seal against moisture along the length of the conductor,
• (d) forming a fluoropolymer outer layer on the polyimide middle layer by extruding a fluoropolymer material along a portion or length of that layer;
• and
• (e) crosslinking the fluoropolymer outer layer, wherein, if the inner layer or the sealable component comprises a perfluoropolymer, the fluoropolymer outer layer is crosslinked by exposing it to less than 60 megarads of radiation, with applied voltages ranging from about 50 to about 120 kilo volts.

A process for preparing an insulated electrical conductor, which comprises:

• (a) forming a polyirnide inner layer on an electrical conductor,
• wherein, the polyimide inner layer is formed by wrapping a polyimide film, which has been coated with a sealable component, in an overlapping fashion, along a portion or length of the electrical conductor, wherein the sealable component is selected from the group of perfluoropolymer, crosslinkable fluoropolymer and polyimide adhesives,
• (b) forming a polyimide middle layer on the inner layer by wrapping a coated polyimide film, in an overlapping fashion, along a portion or length of the inner layer,
• (c) heating the polyimide film or films to a temperature ranging from about 240° to about 350° C. to cause overlapping regions of the coated film or films to bond, thereby forming an effective seal against moisture along the length of the conductor,
• (d) forming a fluoropolymer outer layer on the middle layer by extruding a fluoropolymer material along a portion or length of that layer;
• and
• (e) crosslinking the fluoropolymer outer layer, wherein, if the sealable component comprises a perfluoropolymer, the fluoropolymer outer layer is crosslinked by exposing it to less than 60 megarads of radiation, with applied voltages ranging from about 50 to about 120 kilo volts.

An insulated electrical conductor that comprises an electrical conductor and a multi-layer insulation system, wherein the multi-layer insulation system comprises:

• (a) a polyimide inner layer,
• wherein, the polyimide inner layer is formed by wrapping a polyimide film, which has been coated with a sealable component, in an overlapping fashion, along a portion or length of an electrical conductor,
• wherein, the polyimide film is substantially uniformly sealed to itself in overlapping regions along the length of the conductor, thereby forming an effective seal against moisture,
• wherein, the sealable component is selected from the group of perfluoropolymer, crosslinked fluoropolymer and polyimide adhesives,
• (b) a polyimide middle layer, wherein the polyimide middle layer is formed by wrapping an optionally coated polyimide film, in an overlapping fashion, along a portion or length of the inner layer formed on the electrical conductor, and
• (c) an extruded, crosslinked fluoropolymer outer layer, wherein the fluoropolymer is selected from the group of copolymers and terpolymers of ethylene-tetrafluoroethylene, and mixtures thereof.

An insulated electrical conductor that comprises an electrical conductor and a multi-layer insulation system, wherein the multi-layer insulation system comprises:

• (a) a polyimide inner layer,
• wherein, the polyimide inner layer is formed by wrapping a polyimide film, which has been coated with a sealable component, in an overlapping fashion, along a portion or length of the electrical conductor,
• wherein, the polyimide film is substantially uniformly sealed to itself in overlapping regions along the length of the conductor, thereby forming an effective seal against moisture,
• wherein, the sealable component is selected from the group of perfluoropolymer, crosslinked fluoropolymer and polyimide adhesives, and
• wherein, the polyimide inner layer demonstrates a high temperature (greater than or equal to 150° C.) adhesive bond strength (ASTM # 1876-00) ranging from about 100 to about 250 grams per inch-width , and
• (b) an extruded, crosslinked fluoropolymer outer layer, wherein the fluoropolymer is selected from the group of copolymers and terpolymers of ethylene-tetrafluoroethylene, and mixtures thereof.