Polymer-coated electrical wire

Abstract

The invention provides insulated electrical conductors, such as electrical wires, and methods of making such insulated electrical conductors resistant to partial discharge by enhancing the bond strength between the electrical conductor and a base insulating thermoplastic layer (e.g., comprising a PAEK). Such insulated electrical conductors can include: an electrical conductor; an insulating coating on at least a portion of the surface of the electrical conductor; and an oxide layer between the electrical conductor and the insulating coating. Methods of producing such insulated electrical conductors can include extruding an insulating polymer onto the electrical conductor at ambient atmospheric pressure and a subsequent heat treatment step, which can also be performed at ambient atmospheric pressure.

Description

[0001] This application is a divisional application of the Chinese Patent Application No. 202080006267.5, filed on August 21, 2020, entitled “Polymer Coated Electrical Wire”. TECHNICAL FIELD

[0002] The present application is mainly directed to the field of insulated electrical conductors and methods related to such insulated electrical conductors. BACKGROUND

[0003] Electrical conductors are materials that allow the flow of electric charge (current). Electrical wires are one of the most common forms of electrical conductors and are usually made of metals such as aluminum, copper or alloys thereof. In these electrical conductors, electrons flow, and due to the movement of electrons between atoms and the high speed associated therewith, heat is generated.

[0004] Without the help of electrical insulators, devices containing electrical conductors such as electrical wires cannot function properly. In particular, to prevent overheating / fire problems, to prevent electric shock and to ensure proper functioning and safety of the conductors and devices associated with the conductors, electrical wires are usually coated with an insulator. For example, to avoid air gaps that can cause partial discharges during use, adhesion between the insulating layer and the underlying electrical conductor is very important. For example, discharges can occur between the conductor and the adjacent insulating layer, especially when there is an air gap / delamination between the conductor and the insulating layer (as described above), inside the insulating layer and / or outside the insulating layer (when the material discharges to another wire or motor element in the vicinity, i.e. corona discharge). When electrical wires are gathered to form (as in a wound motor), good adhesion (no or little air gap between the insulating layer and the electrical conductor) is particularly important to mitigate at least the first mode of discharge.

[0005] For a variety of reasons, polymers are a common material for wire insulation. Some polymers have a high electrical resistance, can be flexible (thus bending easily at corners and safely entering electrical boxes), can easily dissipate heat, can burn slowly, and are relatively inexpensive. In particular, polyetherketones such as polyether ether ketone (PEEK) are excellent wire insulation materials due to their typically high temperature operating window and inherent resistance to many chemicals found in industrial and automotive environments. But direct extrusion of thermoplastic polymers such as PEEK over metals (such as those applied within electrical conductors) is often problematic because these thermoplastics often do not adhere well to these metals (as described above, where there are many problems associated with air gaps and delamination). It is believed that the adhesion of these polymers to the conductor is affected by the presence / formation of an oxide layer during the process, and the presence of an oxide layer is generally considered to be detrimental to adhesion in the art. Thus, attempts have been made to de-oxidize the metal surface during the coating / adhesion process to provide an insulation layer over the electrical conductor. See, for example, EP 3 441 986, which is incorporated herein by reference in its entirety. Alternative methods have also been employed to address the adhesion problem, including the application of multiple polymer layers (such as including a baked-on paint layer). See, for example, U.S. Patent Publication No. 2015 / 0021067, which is incorporated herein by reference in its entirety. Delamination between adjacent layers in such multi-layer arrangements can still detrimentally result in the formation of air gaps within the insulated wire.

[0006] There have been some attempts to improve the intimate contact between the insulation and the underlying wire, and thus the adhesion of the insulation to the wire, by applying a "pressure coating" technique. Pressure coating is different from general extrusion in that in pressure coating the wire core / mandrel is retracted into an outer profile die within the thermoplastic extrusion tool. This allows the wire to be coated with high pressure resin before it exits the machine. In pressure coating, a die similar in size to the outer diameter of the product is used, and the wire filaments exit the extruder in the coated form. In contrast, in traditional "jacket or tube coating", a larger tool assembly is applied, and a tube is extruded in the same direction as the wire passes through the machine; the tube is pulled out after exiting the extruder and brought into contact with the conductor. In jacket or tube coating equipment, the forming die and the core / mandrel are flush or nearly flush at the machine exit, and there is an air gap between the tube exit and the conductor. In this manner of running the process, the tube is pulled down into intimate contact with the conductor.

[0007] It is generally believed that pressure coating techniques can improve the "grip" of the insulation layer to the wire, but these techniques do not create any adhesion to the underlying oxide layer on the surface of the wire. In addition, pressure coating can be undesirable compared to other alternative methods such as jacket coating, where a larger tube tool assembly can be applied, because the former allows for lower pressure, easier control of insulation concentricity / uniformity, and faster coated wire speed.

[0008] It is advantageous to provide further methods for preparing a coated electrical conductor, wherein the coated electrical conductor can provide effective adhesion between the polymeric coating and the underlying conductor. SUMMARY

[0009] The present invention provides methods for obtaining a coated (insulated) electrical conductor, and in particular provides methods for creating effective adhesion between an insulating coating and an electrical conductor. The present invention further describes the resulting coated electrical conductor and its properties and characteristics.

[0010] Contrary to conventional understanding, the method for producing a coated electrical conductor developed by the present inventors is carried out in ambient air, without the need for strict attention to exclude oxygen from the atmosphere. The method disclosed herein provides a coated / insulated electrical conductor with sufficient adhesion between the insulating coating and the underlying electrical conductor. As more fully described and demonstrated below, the coated electrical conductor produced by this method advantageously has a strong resistance to delamination of the insulating coating from the electrical conductor.

[0011] In one aspect, the present invention provides an insulated electrical conductor comprising: an electrical conductor comprising an oxide layer on at least a portion of its surface; and an insulating coating on at least a portion of the oxide layer, wherein the insulated electrical conductor exhibits adhesion between the insulating coating and the electrical conductor and / or the oxide layer, such that the insulating coating cannot be peeled off from the electrical conductor. The feature that the insulating coating "cannot be peeled off" can refer to the insulating coating not being able to be pulled off the electrical conductor in a full or partial tubular form (e.g., in ambient conditions / at room temperature in air).

[0012] The electrical conductor properties can vary. In some embodiments, the electrical conductor is an electrical wire. In some embodiments, the electrical conductor has a circular, square, triangular, rectangular, polygonal, or elliptical cross-sectional shape. In some embodiments, the electrical conductor comprises copper, aluminum, or a combination thereof. In particular embodiments, the electrical conductor comprises copper. In some embodiments, the electrical conductor comprises a silver, nickel, or gold coating.

[0013] Similarly, the insulating coating properties can vary. In some embodiments, the insulating coating comprises a polyaryletherketone (PAEK). Exemplary PAEK polymers include, but are not limited to, polyetherketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK), and polyether ketone ether ketone ketone (PEKEKK). In certain embodiments, the insulating coating can further comprise one or more fibers, fillers, or a combination thereof. In some embodiments, the insulating coating comprises a polymeric alloy of a PAEK and one or more fluororesins. In other embodiments, the insulating coating consists essentially of a polymer, such as a PAEK.

[0014] In some embodiments, an insulated electrical conductor is provided, wherein the electrical conductor is an electrical wire having a circular cross-section, and the tan delta damping ratio is less than or equal to 1.10 when measured by the following procedure: a) heating the coated wire in a cantilevered clamp in a DMA instrument from room temperature to a temperature Tl corresponding to the melting endotherm peak (determined by DSC) for the first time; b) cooling the coated wire back to room temperature after one minute at Tl; c) heating the coated wire to Tl for the second time; d) determining the slope of the tan delta curve at the onset of the polymer thermal transition region, ml, during the first heating cycle; e) determining the slope of the tan delta curve at the onset of the polymer thermal transition region, m2, during the second heating cycle; and f) dividing ml by m2 to calculate the tan delta damping ratio.

[0015] In some embodiments, an insulated electrical conductor is provided, wherein the electrical conductor is an electrical wire having a rectangular cross-section, and the tan delta damping ratio is less than 1.60 when measured by the following procedure: a) heating the coated wire in a cantilevered clamp in a DMA instrument from room temperature to a temperature Tl corresponding to the melting endotherm peak (determined by DSC) for the first time; b) cooling the coated wire back to room temperature after one minute at Tl; c) heating the coated wire to Tl for the second time; d) determining the slope of the tan delta curve at the onset of the polymer thermal transition region, ml, during the first heating cycle; e) determining the slope of the tan delta curve at the onset of the polymer thermal transition region, m2, during the second heating cycle; and f) dividing ml by m2 to calculate the tan delta damping ratio.

[0016] In some embodiments, the inability of the insulating coating to be stripped from the electrical conductor is determined by: creating a nick or tear in the insulating coating; attempting to strip the insulating layer from the electrical conductor by the nick or tear in the longitudinal direction of the coated electrical conductor in air at ambient conditions; and observing that the insulating layer cannot be stripped from the electrical conductor in a full or partial tubular form. In some embodiments, an electric motor comprising the insulated electrical conductor disclosed herein is provided.

[0017] In another aspect of the application, a method of making an insulated electrical conductor is provided, comprising: providing an electrical conductor comprising a metal oxide on at least a portion of its surface; extruding a polymeric insulating coating onto at least a portion of the electrical conductor, wherein the extruding is performed under ambient atmospheric conditions; cooling the coated electrical conductor; heat treating the cooled coated electrical conductor; and cooling the heat treated coated electrical conductor to provide an insulated electrical conductor. In some embodiments, the extruding employs a jacketed coating tool. In some embodiments, the extruding employs a pressure coating tool. Thus, in some embodiments, the method provides a unique method involving a pressure coating technique to provide a coated electrical conductor having adhesion between the electrical conductor and the insulating coating that is not typically obtainable from a pressure coating method.

[0018] In certain embodiments, the heat treatment comprises subjecting the cooled coated electrical conductor to or above the glass transition temperature of the polymeric insulating coating. The heat treatment can also comprise holding the heated coated electrical conductor at the temperature for a specified time. In some embodiments, the extrusion and heat treatment are performed at ambient atmospheric pressure. The present invention also includes an insulated electrical conductor prepared according to the method provided herein.

[0019] The present invention includes, but is not limited to, the following embodiments:

[0020] Embodiment 1 : An insulated electrical conductor comprising: an electrical conductor comprising an oxide layer on at least a portion of a surface thereof; and an insulating coating on at least a portion of the oxide layer, wherein the insulated electrical conductor exhibits adhesion between the insulating coating and the electrical conductor and / or the oxide layer such that the insulating coating cannot be peeled from the electrical conductor.

[0021] Embodiment 2: The insulated electrical conductor of the preceding embodiment, wherein the electrical conductor is an electrical wire.

[0022] Embodiment 3: The insulated electrical conductor of any of the preceding embodiments, wherein the electrical conductor has a cross-sectional shape that is circular, square, triangular, rectangular, polygonal, or oval.

[0023] Embodiment 4: The insulated electrical conductor of any of the preceding embodiments, wherein the electrical conductor comprises copper, aluminum, or a combination thereof.

[0024] Embodiment 5: The insulated electrical conductor of any of the preceding embodiments, wherein the electrical conductor comprises copper or a copper alloy.

[0025] Embodiment 6: The insulated electrical conductor of any of the preceding embodiments, wherein the electrical conductor comprises a silver, nickel, or gold coating.

[0026] Embodiment 7: The insulated electrical conductor of any of the preceding embodiments, wherein the insulating coating comprises a polyaryletherketone (PAEK).

[0027] Embodiment 8: The insulated electrical conductor of any of the preceding embodiments, wherein the insulating coating further comprises one or more fibers, fillers, or a combination thereof.

[0028] Embodiment 9: The insulated electrical conductor of any of the preceding embodiments, wherein the insulating coating consists essentially of a polyaryletherketone (PAEK).

[0029] Embodiment 10: The insulated electrical conductor of any of the preceding embodiments, wherein the insulating coating comprises a polymer selected from the group consisting of polyetherketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK), and polyether ketone ether ketone ketone (PEKEKK).

[0030] Embodiment 11. The insulated electrical conductor of any of the preceding embodiments, wherein the insulating coating comprises a polymeric alloy of a PAEK and one or more fluorine-containing resins.

[0031] Embodiment 12. The insulated electrical conductor of any of the preceding embodiments, wherein the electrical conductor is an electrical wire having a circular cross-section with a tan delta damping ratio of less than or equal to 1.10 when measured by the following procedure: a) in a DMA instrument, first heat the cantilevered clamped coated electrical wire from room temperature to a temperature T1 corresponding to the melting endotherm peak (determined by DSC); b) after one minute at T1, cool the coated electrical wire back to room temperature; c) second heat the coated electrical wire to T1; d) during the first heating cycle, determine the slope of the tan delta curve at the onset of the polymer thermal transition region, ml; e) during the second heating cycle, determine the slope of the tan delta curve at the onset of the polymer thermal transition region, m2; and f) divide ml by m2 to calculate the tan delta damping ratio.

[0032] Embodiment 13. The insulated electrical conductor of any of the preceding embodiments, wherein the electrical conductor is an electrical wire having a rectangular cross-section with a tan delta damping ratio of less than 1.60 when measured by the following procedure: a) in a DMA instrument, first heat the cantilevered clamped coated electrical wire from room temperature to a temperature T1 corresponding to the melting endotherm peak (determined by DSC); b) after one minute at T1, cool the coated electrical wire back to room temperature; c) second heat the coated electrical wire to T1; d) during the first heating cycle, determine the slope of the tan delta curve at the onset of the polymer thermal transition region, ml; e) during the second heating cycle, determine the slope of the tan delta curve at the onset of the polymer thermal transition region, m2; and f) divide ml by m2 to calculate the tan delta damping ratio.

[0033] Embodiment 14. The insulated electrical conductor of any of the preceding embodiments, wherein the insulating coating is determined to be non-strippable from the electrical conductor by: creating a nick or tear in the insulating coating; attempting to strip the insulating layer from the electrical conductor by peeling the insulating layer from the nick or tear in the longitudinal direction of the coated electrical conductor in air at ambient conditions; and observing that the insulating layer does not strip from the electrical conductor in a full or partial tubular form.

[0034] Embodiment 15. An electric motor comprising the insulated electrical conductor of any of the preceding embodiments.

[0035] Embodiment 16: A method of making an insulated electrical conductor comprising: providing an electrical conductor comprising an oxide layer on at least a portion of a surface thereof; extruding a polymeric insulating coating onto the electrical conductor and / or the oxide layer such that the insulating coating cannot be peeled from the electrical conductor, wherein the extruding is performed under ambient atmospheric conditions; cooling the coated electrical conductor; heat treating the cooled coated electrical conductor; and cooling the heat treated coated electrical conductor to provide an insulated electrical conductor.

[0036] Embodiment 17: The method of any of the preceding embodiments, wherein the extruding uses a pressure coating tool.

[0037] Embodiment 18: The method of any of the preceding embodiments, wherein the extruding uses a jacketed coating tool.

[0038] Embodiment 19: The method of any of the preceding embodiments, wherein the heat treating comprises subjecting the cooled coated electrical conductor to or above a glass transition temperature of the polymeric insulating coating.

[0039] Embodiment 20: The method of any of the preceding embodiments, wherein the heat treating can further comprise maintaining the heated coated electrical conductor at the temperature for a specified time.

[0040] Embodiment 21 : The method of any of the preceding embodiments, wherein the extruding and heat treating are performed under ambient atmospheric pressure.

[0041] Embodiment 22: The method of any of the preceding embodiments, wherein the electrical conductor is an electrical wire.

[0042] Embodiment 23: The method of any of the preceding embodiments, wherein the electrical conductor has a cross-sectional shape that is circular, square, triangular, rectangular, polygonal, or oval.

[0043] Embodiment 24: The method of any of the preceding embodiments, wherein the electrical conductor comprises copper, aluminum, or a combination thereof.

[0044] Embodiment 25: The method of any of the preceding embodiments, wherein the electrical conductor comprises a silver, nickel, or gold coating.

[0045] Embodiment 26: The method of any of the preceding embodiments, wherein the insulating coating comprises a polyaryletherketone (PAEK).

[0046] Embodiment 27: The method of any of the preceding embodiments, wherein the insulating coating further comprises one or more of a fiber, a filler, or a combination thereof.

[0047] Embodiment 28: The method of any of the preceding embodiments, wherein the insulating coating consists essentially of a polyaryletherketone (PAEK).

[0048] Embodiment 29: The method of any of the preceding embodiments, wherein the insulating coating comprises a polymer selected from the group consisting of polyether ketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK), and polyether ketone ether ketone ketone (PEKEKK).

[0049] Embodiment 30: The method of any of the preceding embodiments, wherein the insulating coating comprises a polymeric alloy of a PAEK and one or more fluorine-containing resins.

[0050] Embodiment 31 : An insulated electrical conductor prepared according to the method of any of the preceding embodiments.

[0051] These and other features, aspects, and advantages of the present application will become better understood with reference to the following detailed description when considered in connection with the accompanying drawings, which are briefly described below. The application includes any combination of two, three, four or more of the above embodiments, as well as any combination of two, three, four or more of the features or factors described in this application, whether or not the features or factors are explicitly described in combination with each other in the specific embodiments described herein. The application requires full reading to understand that any separable feature or factor of the application can be combined in its various aspects and embodiments, unless otherwise explicitly specified by the context. Other aspects and advantages of the application will become more apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0052] For the purposes of promoting an understanding of the principles of the application, reference will now be made to the embodiments illustrated in the drawings. The drawings are not necessarily to scale, and the illustrative figures herein are not intended to limit the scope of the application, as claimed, and various features hereof can be utilized independently of each other or in various combinations.

[0053] Figure 1 is a general schematic of the method of the application;

[0054] Figure 2 is a tan delta dynamic temperature scan of a bare copper wire;

[0055] Figure 3 is a tan delta scan plot of the heat treated sample of Example 1, showing the calculation of the slope in the first (solid line) and second (dashed line) scans; and

[0056] Figure 4 is a tan delta scan plot of the untreated sample of Example 1, showing the calculation of the slope in the first (solid line) and second (dashed line) scans. DETAILED DESCRIPTION

[0057] The present application will be described more fully hereinafter. However, the application can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and fully convey the scope of the application to those skilled in the art. As used in this specification and the claims, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise.

[0058] The present application provides a coated electrical conductor and a method of producing such a coated electrical conductor. As described in greater detail below, the coating is typically an insulating material, such that the coated electrical conductor is an insulated electrical conductor. Surprisingly, the coated electrical conductors provided herein can be produced at ambient atmospheric pressure (e.g., without rigorous oxygen removal), such that the coated electrical conductor includes at least a partial oxide layer between the insulating coating and the electrical conductor. Nonetheless, as demonstrated herein, the insulating coating and the electrical conductor exhibit sufficient adhesion, and in some embodiments, very good adhesion, contrary to conventional wisdom regarding the importance of eliminating such an oxide layer.

[0059] In a first aspect, the present application provides a method for producing a coated electrical conductor as outlined in Figure 1 As shown, the method includes four steps, namely an extrusion step to provide a coated electrical conductor, cooling the resulting coated electrical conductor, a heat treatment step, and a second cooling step to provide the desired product. The extrusion step typically includes melting a thermoplastic polymer and applying it to the surface of the electrical conductor. Pressure or jacketed coating techniques can be employed in the extrusion step of the disclosed method. Extrusion is typically carried out using equipment specifically designed for this purpose, which includes means for guiding the electrical conductor into the die, pulling the electrical conductor through the die, and contacting the electrical conductor with the molten polymer to draw the electrical wire under conditions to produce a predetermined insulating coating thickness. Methods of extruding thermoplastic polymers onto electrical conductors are known. An exemplary method is set forth in https: / / www.victrex.com / ~ / media / literature / en / victrex_extrusion-brochure.pdf, which is incorporated herein by reference in its entirety. Those skilled in the art will recognize that varying process conditions can be used to obtain a consistent insulating coating or varying coating thickness, etc.

[0060] The extrusion of the present application advantageously need not be conducted under oxygen-free conditions. Indeed, in certain embodiments, the extrusion step is conducted under ambient atmosphere (e.g., in (unprocessed) air, where oxygen is not deliberately removed from the atmosphere). Thus, in some embodiments, the extrusion can be described as being conducted in the presence of oxygen. There is no need for a pretreatment step to ensure that the electrical conductor is substantially free of oxides prior to extruding an insulating coating thereon (e.g., plasma treatment under an oxygen-free protective atmosphere, as outlined in EP 3 444 986, which is hereby incorporated by reference in its entirety).

[0061] The materials used in the extrusion can vary. The electrical conductor generally comprises any material suitable for conducting electricity. In particular embodiments, the electrical conductor comprises a metal capable of oxidation, and in some such embodiments, the electrical conductor comprises such a metal on at least a portion of its surface. The electrical conductor generally comprises a metal, such as a material comprising copper, aluminum, or a combination or alloy thereof. In some embodiments, the electrical conductor can comprise a coating thereon, such as a metal coating. The metal coating may, for example, comprise silver, nickel, or gold (providing a conductor having a metal coating / metal plating). While the present application refers to applying a thermoplastic polymer to an electrical conductor, it should be noted that the principles and methods outlined herein can also be used to apply a thermoplastic polymer to other materials, such as materials comprising a metal that is not an electrical conductor.

[0062] The size and shape of the electrical conductor can vary. In certain embodiments, the electrical conductor is an electrical wire. For example, the electrical conductor can be a copper-containing electrical wire (e.g., a copper electrical wire), an aluminum-containing electrical wire (e.g., an aluminum electrical wire), or a copper-plated or aluminum-plated electrical wire. The electrical conductor can have any cross-sectional shape, such as circular, square, triangular, rectangular, polygonal, or oval, so long as the size and shape are compatible with the extrusion equipment employed in the method.

[0063] As is known in the art, the polymeric material applied to the electrical conductor comprises a thermoplastic polymer, e.g., which can be softened and melted by heat, and which can be processed in a liquid state (e.g., by extrusion). In certain embodiments, the polymeric material comprises a polyaryletherketone (PAEK). A PAEK is a semi-crystalline thermoplastic polyketone. The polymeric material generally comprises a majority of PAEK, i.e., at least about 70 wt% PAEK (with the remainder, e.g., fillers, fibers, or other polymers, as described in more detail below). In further embodiments, the polymeric material comprises at least about 80%, at least about 90%, at least about 95%, at least about 98%, or at least about 99 wt% PAEK. In some embodiments, the polymeric material consists essentially of PAEK. Exemplary PAEK polymers include, but are not limited to, those selected from the group consisting of polyetherketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK), and polyether ketone ether ketone ketone (PEKEKK).

[0064] As noted above, in some embodiments, the polymeric material includes one or more additional components in addition to the PAEK. In addition to the PAEK, the polymeric material can generally include any additives suitable for performance enhancement, where the PAEK serves as the primary insulation. In some embodiments, the polymeric material includes the PAEK and one or more fibers, fillers, or combinations thereof. The fibers and / or fillers that can optionally be included in the thermoplastic polymers disclosed herein can be any material known to enhance one or more polymer properties. A variety of relevant fillers are known, and can be employed within the resins and / or corresponding insulation coatings disclosed herein. Certain exemplary fillers and other additives include, but are not limited to, glass spheres, glass fibers, various forms of carbon (such as carbon black, nanotubes, powders, fibers), radiopaque agents such as barium sulfate (BaS04), bismuth subcarbonate, bismuth oxychloride, tungsten, cooling fillers such as boron nitride (BN) matrix, colorants / pigments, processing aids, and combinations thereof.

[0065] In other embodiments, the polymeric material can include one or more additional polymers (such as to provide a polymer alloy with the PAEK). For example, in some embodiments, the polymeric material can include one or more fluoropolymers. A variety of fluoropolymers are known to be readily miscible into PAEKs to a relatively high percentage (such as up to 30%), and such compositions / alloys can be employed in the methods provided herein. In some embodiments, the introduction of one or more fluoropolymers into the PAEK can provide physical benefits, as fluoropolymers generally have excellent electrical properties with respect to dielectric constant and dielectric properties (but are generally less abrasion resistant and non-adhesive), and can impart certain properties to the material, such as reduced friction (which can make the final product easier to install, for example in a tightly packed motor slot). In some embodiments, the amount of additional polymer is kept at a relatively low level, such as so that about 70% or more of the polymeric material is PAEK, or about 80% or more, about 85% or more, about 90% or more, about 95% or more, about 98% or more, or about 99% or more of the polymeric material is PAEK.

[0066] After the extrusion step, the resulting coated electrical conductor is allowed to cool at least slightly, e.g., below the glass transition temperature (Tg) of the material. After cooling, the coated electrical conductor is subjected to a heat treatment. This heat treatment step typically involves treating the coated electrical conductor at an elevated temperature, e.g., at or above the Tg of the insulating coating on the coated electrical conductor. In some embodiments, the temperature can be at or above the melting point (Tm) of the polymeric resin. In various embodiments, any temperature sufficient to at least partially re-melt the resin is sufficient for this heat treatment step. The parameters of the heat treatment are not particularly limited, and the heat treatment can advantageously be carried out in an oxygen-containing atmosphere, e.g., under ambient atmospheric conditions, such as in (un-treated) air. Suitable methods for heating are well known and can be applied in the methods disclosed herein. For example, in various embodiments, the heat treatment step is carried out by subjecting the coated electrical conductor to heat generated within an oven. In various embodiments, the heat treatment step can employ one or more of radiant heating, infrared heating, induction heating, microwave heating, heating by conduction through a fluid, convection heating, and combinations thereof. In some embodiments, the heat treatment comprises a single heating, but is not limited thereto. In some embodiments, the coated electrical conductor is heated two or more times, with cooling in between. In certain embodiments, multiple heating is desirable to ensure that the coating melts and is able to flow to achieve adequate adhesion.

[0067] In the heat treatment step, the coated electrical conductor is heated (one or more times, as described above) and then held at the elevated temperature for a given period of time. This period of time can vary, and can be, for example, a few seconds or minutes to several hours. As one example, in some embodiments, the heating is carried out by placing the coated electrical conductor into an oven and holding it therein for about 1 minute or more, e.g., from about 1 minute to about 2 hours or from about 5 minutes to about 30 minutes.

[0068] After the heat treatment, the heat treated coated electrical conductor is allowed to cool, for example to ambient temperature. The resulting coated electrical conductor surprisingly exhibits adequate, even superior adhesion between the electrical conductor and the insulating coating thereon. In particular, it has been found that such coated electrical conductors are highly resistant to delamination of the insulating coating from the underlying electrical conductor. Thus, it has been surprisingly found that the methods outlined herein result in unique properties associated with the resulting coated electrical conductors. While not intending to be bound by theory, it is believed that the multi-step process outlined herein, including extrusion, cooling and reheating the coated electrical conductor, provides a coated product with excellent adhesion between the metal oxide layer on the conductor surface and the PAEK present in the adjacent polymeric insulating material. The test data referenced in the Examples below in the form of a small plate test demonstrate that, in fact, the adhesion strength created between the metal oxide and the PAEK is unexpectedly greater than the adhesion strength between the metal oxide and the conductor metal. It is noted that in some embodiments, it can be beneficial to measure changes in the dynamic mechanical response of the coated electrical conductor (to be described in greater detail below) to confirm that the conditions in the disclosed process provide adequate adhesion between the conductor and the insulating layer.

[0069] The coated electrical conductors provided herein include an electrical conductor and an insulating coating thereon with a metal oxide between the electrical conductor and the insulating coating, which distinguishes them from certain known coated electrical conductors. It will be appreciated that the particular metal oxide present will depend on the composition of the electrical conductor (e.g., a copper electrical conductor will include copper oxide). The extent of the oxide present between the electrical conductor and the insulating coating can vary depending on the processing conditions, such as the particular environment in which the process steps are carried out, the time the materials are held at elevated temperatures in the heat treatment step, and the temperature of the extrusion and / or heat treatment, among others. As noted above, while not quantified, it is believed that the disclosed coated conductors include strong adhesion between the metal oxide present on the surface of the electrical conductor and the PAEK of the insulating polymer. Again, while not intending to be bound by theory, it is believed that the presence of these adhesions between the PAEK of the insulating polymer and the metal oxide results in the strength / integrity of the coated product such that they are largely immune to the type of peeling described herein relative to conventional products.

[0070] The coated electrical conductors of the present invention are distinguished from certain known coated electrical conductors not only by the type of oxide and adhesion created thereby, but also by their physical properties, i.e., the strength of the adhesion between the electrical conductor and the insulating coating. The strength of the adhesion can be evaluated in various ways.

[0071] In some embodiments, the disclosed coated electrical conductor is described in terms of the manual peelability (also referred to herein as "peelability") of the insulating coating from the underlying electrical conductor. A peelable insulating coating can be easily peeled away from the electrical conductor in a tubular form. As peelability decreases, this becomes increasingly unlikely, and instead the insulating coating is peeled away as a fragment. For example, a manual peel test can be performed in which a nick / tear is formed in the insulating coating and the insulating coating is peeled along the length of the coated electrical conductor to attempt to peel the insulating coating from the electrical conductor. A product with insufficient adhesion tends to peel along the length of the coated electrical conductor in long, intact pieces of insulating coating. A product within the scope of the present invention does not have this peelability. Instead, the disclosed coated electrical conductor has sufficient adhesion that no appreciable degree of peeling occurs (e.g., the insulating layer cannot be peeled from the underlying electrical conductor in a complete or partial tubular form). See the non-limiting example of verifying manual peel.

[0072] In certain embodiments, the coated electrical conductor of the present invention exhibits only the formation of a small fragment of the insulating coating when a nick / tear is attempted to be formed and / or peeled. Each of the various products described herein have the latter property, i.e., the insulating coating does not readily peel from the underlying electrical conductor. In some embodiments, the disclosed coated electrical conductor does not have a significant delamination (including no delamination) between the insulating coating and the electrical conductor after an invasive forming. Invasive forming is generally understood in the art to mean, for round electrical wires, wrapping around its own inner diameter and checking for wrinkles or delamination in the inner diameter (ID) of the formed body. For rectangular cross-sections, the wrapping can instead be a partial bend on the long axis, short axis, a spiral bend at any inner diameter, or handling all twists without significant delamination, cracking, or detrimental damage. Delamination is a failure mode in which a material separates into layers (here, the insulating coating separates from the electrical conductor). Delamination can be easily observed visually, i.e., by observing the interface between the electrical conductor and the insulating coating. In various embodiments, no delamination is advantageously observed by the naked eye (i.e., without magnification) before and after subjecting the disclosed coated electrical conductor to the invasive forming method. Various test methods are known and can also be used to assess the absence of delamination.

[0073] In some embodiments, the disclosed coated electrical conductors are described by the degree of adhesion strength verified by damping the dynamic mechanical response. It has been found that the degree of processing can hinder the dynamic mechanical response of a polymer-coated electrical wire, and that this damping is an indicator of the adhesion of the polymer to the electrical wire. The damping can be measured on a dynamic mechanical analyzer (DMA) by a dynamic temperature sweep of tan delta. See, for example, K. P. Menard, Dynamic Mechanical Analysis: A Practical Introduction, CRC Press, 1999, which is incorporated herein by reference. Tan delta is defined as the ratio of the loss modulus (E") to the storage modulus (E'), and thus represents the damping due to viscous dissipation of energy. This analysis is very similar to the heat treatment step of the disclosed process (taking the coated electrical wire and examining its dynamic response in the first and second heat treatments, where the second heat is to the product after heat treatment).

[0074] For example, if a dynamic temperature sweep is performed on a bare copper wire, the plot of tan delta versus temperature shows no significant transition peak. See, for example, Figure 1. Figure 2 If an insulated copper electrical wire is subjected to the same DMA procedure, the plot of tan delta versus temperature will exhibit a clear transition in the typical range of the insulating polymer, as shown in Figure 3 and 4 As an example, the transition for PEEK begins above 150°C.

[0075] It has been recognized that a strongly adhering insulating coating will have a damped response in the tan delta transition region compared to a weakly adhering polymer layer. This effect can be quantified by calculating the slope of the curve at the onset of the thermal transition during the first dynamic temperature sweep. The insulated electrical wire is then held at its highest melting temperature (as determined by differential scanning calorimetry, DSC) for one minute, and then cooled to room temperature. The second slope is then calculated during a subsequent dynamic temperature sweep. The degree of damping is quantified by dividing the slope obtained during the first sweep by the slope obtained during the second sweep.

[0076] The inventors have found that the degree of tan delta damping is indicative of the adhesion between the polymer and the electrical conductor. For certain embodiments, when the adhesion is insufficient, such as for a wire having a round cross-section, the ratio is greater than 1.10. In other words, when the adhesion is poor, the heating of the insulator and the wire during the dynamic temperature sweep causes a significant change in the slope of tan delta during the two thermal cycles. Figure 3 One such exemplary embodiment is described. However, in this embodiment, when the adhesion is good, the effect of the heating cycle on tan delta is weaker, and the ratio is less than or equal to 1.10. Figure 4 One such exemplary embodiment is described.

[0077] This DMA slope indicates the tightness of the contact between the electrical conductor and the insulating coating. An unbonded electrical wire will exhibit a small slip at the electrical conductor / insulating layer interface. When the first DMA cycle is run on an untreated electrical wire, this effectively reproduces the heat treatment step of the disclosed process (as described in detail above). If the bonding has improved, the electrical wire will exhibit a different response on the second DMA cycle due to the copper oxide layer attached to the substrate. For a well-bonded sample (as provided by the disclosed process), the slope difference is much smaller because the initial small slip has been eliminated by bonding to the underlying copper oxide layer.

[0078] In one specific embodiment, a coated electrical conductor in the form of an electrical wire having a circular cross-section is provided having a tan delta damping ratio of less than or equal to 1.10 when measured as follows: a) heating the cantilevered coated electrical wire in a DMA instrument from room temperature to a temperature T1 corresponding to the melting endotherm peak (as determined by DSC) for the first time; b) cooling the coated electrical wire back to room temperature after one minute at T1; c) heating the coated electrical wire to T1 for the second time; d) determining the slope of the tan delta curve at the onset of the polymer thermal transition region, ml, during the first heating cycle; e) determining the slope of the tan delta curve at the onset of the polymer thermal transition region, m2, during the second heating cycle; and f) dividing ml by m2 to calculate the tan delta damping ratio.

[0079] In another specific embodiment, a coated electrical conductor in the form of an electrical wire having a rectangular cross-section is provided having a tan delta damping ratio of less than 1.60 when measured as follows: a) heating the cantilevered coated electrical wire in a DMA instrument from room temperature to a temperature T1 corresponding to the melting endotherm peak (as determined by DSC) for the first time; b) cooling the coated electrical wire back to room temperature after one minute at T1; c) heating the coated electrical wire to T1 for the second time; d) determining the slope of the tan delta curve at the onset of the polymer thermal transition region, ml, during the first heating cycle; e) determining the slope of the tan delta curve at the onset of the polymer thermal transition region, m2, during the second heating cycle; and f) dividing ml by m2 to calculate the tan delta damping ratio.

[0080] In another embodiment, a method for obtaining a coated electrical conductor having a sufficient level of adhesion between the electrical conductor and the insulating coating is provided. The "sufficient level" can vary and can be defined, for example, by any of the methods outlined herein. The method generally includes controlling the various parameters of the methods described herein to obtain a particular damping of the dynamic mechanical response of the product (e.g., for a circular cross-section electrical wire, a tan delta damping ratio of less than or equal to 1.10, and for a rectangular cross-section electrical wire, a tan delta damping ratio of less than 1.60).

[0081] It should be noted that DMA testing can be affected by the presence of large amounts of fillers / additives / other polymers in the polymeric insulating coating, for example. Thus, in some embodiments, the test methods and results provided herein for DMA are particularly relevant for PAEK-based polymeric insulating coatings having a low concentration of other components (e.g., less than about 10% other components, less than about 5% other components, or less than about 2% other components). As a general consideration, when the DSC trace of the insulating coating is deemed to be complex, it is not suitable for evaluation with the DMA method.

[0082] As described below, certain properties of the coated electrical conductors provided herein can be further described based on the partial discharge exhibited in response to longitudinal stretching. A given strain (e.g., 20% strain) is applied to the heat-treated and comparative (un-heat treated) coated electrical wires. This test is advantageously designed to exclude corona discharge from the surface of the wire, and to show only defects on the electrical conductor or within the insulating layer itself. The wire is wrapped around a mandrel having a diameter of 5 times the diameter of the wire for 2 turns, simulating the forming or bending radius in which the wire is installed into a system in motor winding applications. This test is designed to determine whether there is a significant air gap between the electrical conductor and the insulating layer (which indicates whether there is sufficient adhesion between the electrical conductor and the insulating layer) once the product is subjected to stress and forming. As described in more detail below, a high partial discharge (e.g., greater than 20 pC PD) at a low voltage value (e.g., less than 6000 VAC) is indicative of the presence of a significant air gap.

[0083] To rule out corona (surface discharge) typical in twisted pair PDIV testing where a discharge can occur at the outer air gap, the wire coil wrapped on the mandrel is immersed in a saturated salt water bath. The salt water bath has a ground electrode submerged below the water surface for testing. This salt water bath effectively takes all the charge off the surface of the wire directly to the submerged ground, thus no corona effects are seen on the PD measurement circuit. A person skilled in the art of electrical testing can readily identify corona discharge on the surface of the wire, which can be seen and heard as a characteristic hum, and the results caused by this surface corona should be ignored. The specific insulating fluid in the illustrated embodiment is silicone oil. This treatment / testing (including the described strain and mandrel forming) simulates submersion treatment and motor winding, which are typical conditions to which coated electrical conductors are subjected. Thus, in some embodiments, these results can be particularly relevant to evaluating whether a given product exhibits good adhesion capability under the conditions in which it will be used. In certain embodiments, the coated electrical conductors disclosed in the test exhibit a value of 6000 VAC or greater without a sustained 20 pC discharge. Note that for each embodiment, this test does not always have a conclusion, for example, very thin coated electrical conductors can fail before 6000 VAC, but for certain coated electrical conductors, evaluating adhesion strength in this manner is a useful method that can confirm that the product has sufficient performance to be used without significant delamination in the relevant situation.

[0084] The 20% strain and subsequent submersion forming to create an air gap are designed into this test method. Products subjected to the methods provided in the present disclosure do not exhibit partial discharge similar to previously disclosed values (up to 6000 VAC) or dielectric failure in the bath (for very thin coatings). After 20% strain and submersion forming, no sustained discharge of more than 20 Pc or less occurs in properly adhered wires (provided by the methods disclosed herein). Occasionally, a wire that is not adhered can experience 20% strain and submersion forming without creating an air gap; this also does not show a sustained discharge of 20 pC, but is evident in the slope analysis for the DMA test response upon heat treatment. Thus, in some embodiments, the partial discharge analysis and DMA analysis discussed above, in combination, can be particularly suitable for analyzing coated electrical wires.

[0085] It should be understood that the disclosed coated electrical conductors and related methods are not limited to electrical conductors having a single layer of insulation (e.g., PAEK) thereon. Rather, the present invention is intended to further include products having one or more additional coating layers applied thereon. As described or demonstrated herein, the present inventors have uniquely developed the ability to form a strong bond between an electrical conductor and a thermoplastic polymer coating. Once such a first coating layer (as described herein) is obtained, the other layers are no longer specifically limited. Thus, coated electrical conductors having one, two, three, four, five, or more additional layers are also within the scope of the present invention, where the additional layers can be the same or different, and can include, for example, any polymer that bonds to the insulating coating polymer by co-extrusion or subsequent layering. Such optional additional layers can all be polymers, or can contain any of the types of fillers and / or additives described above. The insulated electrical conductors disclosed herein can be used in different applications. For example, in some embodiments, the present invention provides an electric motor comprising one or more of the insulated electrical conductors described herein.

[0086] Examples

[0087] Example 1 : PEEK (Vestakeep 5000G) on AWG 15 copper wire

[0088] Two samples were prepared, one with a heat treatment step and the other without. The wire was AWG 15 copper wire, and a 3 / 4" 24:1 thermoplastic extruder was used to apply a 0.006" nominal PEEK insulation layer using a tube coating crosshead at a rate of 9 FPM. The wire was preheated to approximately 400°F in an oxygen containing environment (ambient air) using an external heat source prior to coating. The thermoplastic PEEK was drawn over the AWG 15 wire using a 0.285" die and a 0.210 mandrel (designed for a jacketing coating technique, which is generally considered to be detrimental to the formation of a bond). After extrusion, each coated product was allowed to fully cool. One product was not further processed, while the other product was subsequently heated (melted) above the PEEK glass transition temperature, and cooled in ambient air. The methods used to characterize these samples, as well as all characterization data, are given in Table 1 of Example 5 below.

[0089] Manual peelability

[0090] The adhesion strength between the insulating coating and the electrical conductor was evaluated using a manual peeling method. A length of 1.5" was removed from the periphery of the insulated electrical wire near one end. The insulating coating was then cut open with a razor blade for a length of 0.5" from that end. The effort required to separate the insulating coating from the electrical wire was then evaluated on a scale of 1-3. If the insulating layer peeled off with little or no effort after cutting, a value of 1 was taken. If effort was required to initiate peeling of the insulating layer, but once started, it was easy to peel, a value of 2 was taken. If the insulating layer could not be peeled, or if the peel was less than 0.125" across the section, a value of 3 was taken. The manual peeling test resulted in a value of "1" for the unheat treated sample, and a value of "3" for the heat treated sample.

[0091] Damping ratio

[0092] The thermal behavior of the sample was characterized using a TA Instruments DSC Q2000, applying ASTM D3418-15: Standard Test Method for Transition Temperatures and Enthalpies of Fusion and Crystallization of polymers by Differential Scanning Calorimetry, 2015. The insulating layer was removed from the electrical conductor and equilibrated at 30 °C in an aluminum pan, then heated to 400 °C at a constant rate of 10 °C / min. The sample was then cooled back to 30 °C applying a constant rate of 10 °C / min. The sample was heated again to 400 °C at a rate of 10 °C / min. The DSC data was analyzed using TA Instruments Universal Analysis 2000 v4.5A software. The melting endotherm peak was determined to be 339 °C.

[0093] DMA testing was performed based on ASTM D4065-12 to determine tan delta curves in dynamic temperature scans: Standard Practice for Plastics: Dynamic Mechanical Properties: Determination and Report of Procedures, 2012, which is incorporated herein by reference. TA instruments Q800 DMA with a cantilever clamp was applied to determine tan delta by dynamic temperature scans from room temperature to 339°C with a 1 minute isothermal hold at 339°C. The sample was heated at a constant rate of 3°C / min while the 30 pm constant amplitude was replaced with a fixed frequency flexural oscillation at 1 Hz. After the initial temperature scan was completed, the sample was cooled to room temperature. A second dynamic temperature scan was then applied using the same parameters as the initial heating ramp. After both heating cycles were completed, the DMA data was imported into OriginLab’s OriginPro 2019 bv.9.65 data analysis and graphing software. The slope corresponding to the inflection point after the thermal transition of the insulation layer was calculated. The ratio of the slopes obtained from each dynamic temperature scan was then obtained by dividing the first slope by the second slope. For the sample that was not heat treated, this ratio was 1.65. For the sample that was heat treated, this ratio was 0.76.

[0094] Example 2: PEEK (Solvay KT-820NT) on AWG 15 copper wire

[0095] Two samples were prepared, one with a heat treatment step and the other without. These samples were prepared similarly to the samples of Example 1, with the difference being that a different PEEK resin was applied, and the extrusion rate was 8 feet / minute. Characterization data is given in Table 1 below in Example 5.

[0096] Example 3: PEEK (Victrex 381G) on AWG 18 copper wire

[0097] Two samples were prepared, one with a heat treatment step and the other without (prepared similarly to the method of Example 1 above). The wire was AWG 18 copper wire, and a 0.00145" nominal PEEK insulation layer was applied using a tubular coating crosshead using a 3 / 4" 24:1 thermoplastic extruder at a rate of 15.5 FPM. The wire was preheated to approximately 400°F using an external heat source prior to coating. The thermoplastic PEEK was drawn over the AWG 18 wire using a 0.253" die and a 0.200 mandrel. After extrusion, each coated product was allowed to cool completely. One product was not further processed, while the other product was subsequently heated (melted) above the PEEK glass transition temperature for 1 hour and cooled in ambient air. Characterization data is given in Table 1 below in Example 5.

[0098] Comparative Example 1 : Dacon D-20 AP K2 AWG 20 copper wire.

[0099] This is a commercially available product (copper wire coated with PEEK) with a nominal wall thickness of 0.003 for comparison. The PEEK coating is easily stripped from the coated product with a wire stripper and does not maintain formability.

[0100] Example 4: PEEK (Victrex 150G) on AWG 20.5 copper wire

[0101] The sample was prepared with a heat treatment step (similar to the corresponding method of Example 1 above). The wire was AWG 20.5 copper wire and a 0.0039" nominal PEEK insulation layer was applied. The wire was preheated to about 400°F with an external heat source prior to coating. After extrusion, the coated product was allowed to cool completely. It was then heated (melted) above the PEEK glass transition temperature for 1 hour and cooled in ambient air. Characterization data is given in Table 1 below for Example 5.

[0102] Example 5: PEEK (Solvay KT-820NT) on rectangular copper wire.

[0103] Two samples were prepared, one with a heat treatment step and one without (prepared similarly to the method of Example 1 above). The wire was rectangular copper wire and a 0.0075" nominal PEEK insulation layer was applied using a 1" 24:1 thermoplastic extruder at a rate of 3.6 FPM with a tube coating crosshead. The wire was preheated to about 400°F with an external heat source prior to coating. The thermoplastic PEEK was stretched over the rectangular wire using a 0.400" die and a 0.361 mandrel. After extrusion, each coated product was allowed to cool completely. One product was not further processed and the other was then heated (melted) above the PEEK glass transition temperature for 1 hour and cooled in ambient air. Characterization data is given in Table 1 below for this example.

[0104] The different resins and wires tested in the various examples show little or no change for the selected particular resin or the selected particular wire (size and / or shape). It is therefore understood that the methods disclosed herein are not resin grade specific and that PAEK resins as well as filled and alloyed resins are also suitable for application of the disclosed methods (e.g. tan delta reduction based on heat treatment values, adhesion improvement and possible forming without significant delamination, etc.).

[0105] Table 1:

[0106]

[0107] Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing description. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. An insulated electrical conductor comprising: an electrical conductor comprising an oxide layer on at least a portion of a surface of the electrical conductor; and an insulating coating on at least a portion of the oxide layer, wherein the electrical conductor comprises a metal and the oxide layer comprises an oxide of the metal, wherein: the electrical conductor is an electrical wire having a circular cross-section with a tan delta damping ratio of less than or equal to 1.10 when measured by the following procedure: a) heating a cantilevered, coated electrical wire from room temperature to a temperature T1 corresponding to the melting endotherm peak determined by differential scanning calorimetry in a dynamic mechanical analyzer in a first heating cycle; b) cooling the coated electrical wire back to room temperature after one minute at T1 ; c) heating the coated electrical wire to T1 in a second heating cycle; d) determining the slope of the tan delta curve at the onset of the polymer thermal transition region during the first heating cycle, ml ; e) determining the slope of the tan delta curve at the onset of the polymer thermal transition region during the second heating cycle, m2; and f) calculating the tan delta damping ratio by dividing ml by m2.

2. The insulated electrical conductor of claim 1, wherein the electrical conductor has a circular, square, triangular, rectangular, polygonal, or elliptical cross-sectional shape.

3. The insulated electrical conductor of claim 1, wherein the electrical conductor comprises copper, aluminum, or a combination or alloy thereof.

4. The insulated electrical conductor of claim 3, wherein the electrical conductor comprises copper or a copper alloy.

5. The insulated electrical conductor of claim 1, wherein the electrical conductor comprises a silver, nickel, or gold coating.

6. The insulated electrical conductor of claim 1, wherein the insulating coating comprises a polyaryletherketone.

7. The insulated electrical conductor of claim 1, wherein the insulating coating further comprises one or more fibers, fillers, or a combination thereof.

8. The insulated electrical conductor of claim 1, wherein the insulating coating consists of a polyaryletherketone.

9. The insulated electrical conductor of claim 1, wherein the insulating coating comprises a polymer selected from the group consisting of polyetherketone, polyether ether ketone, polyether ketone ketone, polyether ether ketone ketone, and polyether ketone ether ketone ketone.

10. The insulated electrical conductor of claim 1, wherein the insulating coating comprises a polymeric alloy of a polyaryletherketone and one or more fluorine-containing resins.

11. The insulated electrical conductor of claim 1, wherein the insulating coating is incapable of being stripped from the electrical conductor by the following procedure: creating a nick or tear in the insulating coating; attempting to strip the insulating coating from the electrical conductor by peeling the insulating coating from the nick or tear in a longitudinal direction of the coated electrical conductor in air at ambient conditions; and observing that the insulating coating is incapable of being stripped from the electrical conductor in a full or partial tubular form.

12. An electric motor comprising the insulated electrical conductor of claim 1.

13. A vehicle comprising the electric motor of claim 12.

14. A scooter or bicycle comprising the electric motor of claim 12.

15. A generator comprising the insulated electrical conductor of claim 1.

16. A transformer comprising the insulated electrical conductor of claim 1.

17. A method of making the insulated electrical conductor of claim 1, comprising: An electrical conductor is provided including an oxide layer on at least a portion of a surface of the electrical conductor; A polymeric insulating coating is extruded onto one or more of the electrical conductor and the oxide layer such that the insulating coating is not strippable from the electrical conductor, wherein the extruding is performed under ambient atmospheric conditions; The coated electrical conductor is cooled; The cooled coated electrical conductor is heat treated; The heat treated coated electrical conductor is cooled to provide the insulated electrical conductor.

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