INSULATED ELECTRIC CONDUCTOR

Abstract

In order to increase the adhesion of an insulating coating (2) to an electric conductor (1), preferably of copper or aluminum, an insulated electric conductor comprising an electric conductor (1), preferably made of copper or aluminum, with an insulating coating (2) is proposed according to the invention, wherein the insulating coating (2) either comprises at least one insulating layer (3) made of thermoplastic material, or the insulating layer (3) and a plastic-containing intermediate layer (4, 5), obtainable by a method in which the electric conductor (1) is placed under a protective gas atmosphere and is bombarded with ions of the protective gas in a gas plasma in order to remove an oxide layer formed on a surface of the electric conductor (1) and/or to increase the surface energy of the electric conductor (1), and subsequently either the at least one insulating layer (3) or, in the case that the coating (2) comprises the plastic-containing intermediate layer (4, 5), at least the plastic-containing intermediate layer (4, 5) is applied directly to the surface of the electric conductor (1) under a protective gas atmosphere.

Claims

1. An insulated electric conductor, comprising an electric conductor having an insulating coating, wherein the insulating coating either comprises at least one insulating layer made of thermoplastic material, or at least one insulating layer made of thermoplastic material and a plastic-containing intermediate layer, obtainable by a method in which the electric conductor is placed under a protective gas atmosphere and is bombarded with ions of the protective gas in a gas plasma in order to remove an oxide layer formed on a surface of the electric conductor and/or to increase the surface energy of the electric conductor, and subsequently either the at least one insulating layer is applied directly to the surface of the electric conductor under protective gas atmosphere or, in case the coating comprises the plastic-containing intermediate layer, at least the plastic-containing intermediate layer is applied directly under protective gas atmosphere to the surface of the electric conductor.

2. The insulated electric conductor according to claim 1, wherein the electric conductor is placed continuously under protective gas atmosphere until the application of the insulating coating in order to prevent the formation of a new oxide layer on the surface of the electric conductor.

3. The insulated electric conductor according to claim 1, wherein the gas plasma for bombarding the electric conductor is a low-pressure plasma.

4. The insulated electric conductor according to claim 1, wherein the insulating coating has a temperature resistance of at least 180 C.

5. The insulated electric conductor according to claim 1, wherein the thermoplastic material of the at least one insulating layer is selected from the group consisting of polyaryletherketone [PAEK], polyimide [PI], polyamideimide [PAI], polyetherimide [PEI], polyphenylene sulfide [PPS] and combinations thereof.

6. The insulated electric conductor according to claim 1, wherein the thermoplastic material of the at least one insulating layer is a polyaryletherketone [PAEK] selected from the group consisting of polyetherketone [PEK], polyetheretherketone [PEEK], polyetherketoneketone [PEKK], polyetheretherketoneketone [PEEKK], polyetherketoneetherketoneketone [PEKEKK] and combinations thereof.

7. The insulated electric conductor according to claim 1, wherein the at least one insulating layer has a thickness between 10 and 1000 m.

8. The insulated electric conductor according to claim 1, wherein the at least one insulating layer can be produced by means of an extrusion method.

9. The insulated electric conductor according to claim 1, wherein the insulating coating consists of the at least one insulating layer.

10. The insulated electric conductor according to claim 9, wherein the insulating coating consists of one insulating layer or two insulating layers or at least two insulating layers.

11. (canceled)

12. The insulated electric conductor according to claim 1, wherein at least one further insulating layer made of thermoplastic material is applied to the insulating coating, wherein the at least one further insulating layer is not applied under a protective gas atmosphere.

13. The insulated electric conductor according to claim 12, wherein the thermoplastic material of the at least one further insulating layer is selected from the group consisting of polyaryletherketone [PAEK], polyetheretherketone [PEEK], polyimide [PI], polyamideimide [PAI], polyetherimide [PEI], polyphenylene sulfide [PPS] and combinations thereof.

14. (canceled)

15. (canceled)

16. (canceled)

17. The insulated electric conductor according to claim 1, wherein the insulating coating has at least one fluoropolymer layer, and the plastic-containing intermediate layer which is applied directly to the surface of the electric conductor consists of the fluoropolymer layer.

18. The insulated electric conductor according to claim 17, wherein the fluoropolymer layer comprises polytetrafluoroethylene [PTFE] or perfluoroethylene propylene [FEP].

19. The insulated electric conductor according to claim 17, wherein the thickness of the at least one fluoropolymer layer is between 1 m and 120 m.

20. The insulated electric conductor according to claim 17, wherein the entire insulating coating is applied to the electric conductor under-protective gas atmosphere.

21. An insulated electric conductor, comprising an electric conductor having an insulating coating, wherein the insulating coating either comprises at least one insulating layer made of thermoplastic material, or at least one insulating layer made of thermoplastic material and a plastic-containing intermediate layer, further comprising that an oxide layer formed on a surface of the electric conductor is removed by bombardment of the electric conductor with ions of a protective gas of a protective gas atmosphere in a gas plasma, and subsequently either the at least one insulating layer is applied directly to the oxide-layer-free surface of the electric conductor or, in case the coating comprises the plastic-containing intermediate layer, at least the plastic-containing intermediate layer is applied directly to the oxide-layer-free surface of the electric conductor.

22. (canceled)

23. The insulated electric conductor according to claim 21, wherein the thermoplastic material of the at least one insulating layer is selected from the group consisting of polyaryletherketone [PAEK], polyimide [PI], polyamideimide [PAI], polyetherimide [PEI], polyphenylene sulfide [PPS] and combinations thereof.

24. The insulated electric conductor according to claim 21, wherein the thermoplastic material of the at least one insulating layer is a polyaryletherketone [PAEK] selected from the group consisting of polyetherketone [PEK], polyetheretherketone [PEEK], polyetherketoneketone [PEKK], polyetheretherketoneketone [PEEKK], polyetherketoneetherketoneketone [PEKEKK], and combinations thereof.

25. (canceled)

26. (canceled)

27. The insulated electric conductor according to claim 21, wherein the insulating coating consists of the at least one insulating layer.

28. The insulated electric conductor according to claim 27, wherein the insulating coating consists of one insulating layer or two insulating layers or at least two insulating layers.

29. (canceled)

30. The insulated electric conductor according to claim 21, wherein at least one further insulating layer of thermoplastic material is applied to the insulating coating, wherein the at least one further insulating layer is not applied under protective gas atmosphere.

31. The insulated electric conductor according to claim 30, wherein the thermoplastic material of the at least one further insulating layer is selected from the group consisting of polyaryletherketone [PAEK], polyetheretherketone [PEEK], polyimide [PI], polyamideimide [PAI], polyetherimide [PEI], polyphenylene sulfide [PPS] and combinations thereof.

32. (canceled)

33. (canceled)

34. (canceled)

35. (canceled)

36. (canceled)

37. (canceled)

38. (canceled)

39. A method for producing an insulated electric conductor, which comprises the following method steps: bombarding an electric conductor which is arranged under a protective gas, with ions of the protective gas in a gas plasma in order to remove an oxide layer formed on the surface of the electric conductor and/or to increase the surface energy of the electric conductor; applying an insulating coating to the surface of the electric conductor, wherein the insulating coating comprises either at least one insulating layer made of thermoplastic material, or at least one insulating layer made of thermoplastic material and a plastic-containing intermediate layer, wherein either the at least one insulating layer is applied directly to the surface of the electric conductor under protective gas atmosphere or, in case the coating comprises the plastic-containing intermediate layer, at least the plastic-containing intermediate layer is applied directly under protective gas atmosphere to the surface of the electric conductor.

40. The method according to claim 39, wherein the thermoplastic material of the at least one insulating layer is selected from the group consisting of polyaryletherketone [PAEK], polyimide [PI], polyamideimide [PAI], polyetherimide [PEI], polyphenylene sulfide [PPS] and combinations thereof.

41. The method according to claim 39, wherein the thermoplastic material of the at least one insulating layer (3) is a polyaryletherketone [PAEK] selected from the group consisting of polyetherketone [PEK], polyetheretherketone [PEEK], polyetherketoneketone [PEKK], polyetheretherketoneketone [PEEKK], polyetherketoneetherketoneketone [PEKEKK] and combinations thereof.

42. The method according to claim 39, wherein the at least one insulating layer is extrusion-coated.

43. The method according to claim 39, wherein the electric conductor is brought to a temperature of at least 200 C. before the application of the insulating coating.

44. The method according to claim 42, wherein the insulated electric conductor is cooled after the extrusion-coating of the at least one insulating layer depending on the achievable strength of the at least one insulating layer.

45. The method according to claim 42, wherein the insulated electric conductor is guided via rollers after the extrusion-coating of the at least one insulating layer.

46. The method according to claim 42, wherein the insulating coating consists of the at least one insulating layer.

47. The method according to claim 46, wherein the insulating coating consists of at least two insulating layers and the insulating coating is produced by tandem extrusion under a protective gas atmosphere.

48. The method according to one claim 46, wherein at least one further insulating layer of thermoplastic material is extrusion-coated onto the insulating coating by means of tandem extrusion, wherein the extrusion of the at least one further insulating layer does not take place under protective gas atmosphere.

49. The method according to claim 48, wherein the thermoplastic material of the at least one further insulating layer is selected from the group consisting of polyaryletherketone [PAEK], in particular polyetheretherketone [PEEK], polyimide [PI], polyamideimide [PAI], polyetherimide [PEI], polyphenylene sulfide [PPS] and combinations thereof.

50. (canceled)

51. The method according to claim 42, wherein the insulating coating comprises at least one at least one fluoropolymer layer and the fluoropolymer layer is applied as a plastic-containing intermediate layer of the insulating coating under protective gas atmosphere directly to the surface of the electric conductor.

52. The method according to claim 51, wherein at least one fluoropolymer layer and the at least one insulating layer are produced by co-extrusion or tandem extrusion.

53. (canceled)

54. The insulated electric conductor according to claim 5, wherein the at least one insulating layer has a thickness between 10 and 1000 m.

55. The insulated electric conductor according to claim 6, wherein the at least one insulating layer has a thickness between 10 and 1000 m.

56. The insulated electric conductor according to claim 5, wherein the at least one insulating layer can be produced by means of an extrusion method.

57. The insulated electric conductor according to claim 6, wherein the at least one insulating layer can be produced by means of an extrusion method.

58. The insulated electric conductor according to claim 5, wherein the insulating coating consists of the at least one insulating layer.

59. The insulated electric conductor according to claim 6, wherein the insulating coating consists of the at least one insulating layer.

60. The insulated electric conductor according to claim 23, wherein the insulating coating consists of the at least one insulating layer.

61. The insulated electric conductor according to claim 24, wherein the insulating coating consists of the at least one insulating layer.

62. The method according to claim 40, wherein the at least one insulating layer is extrusion-coated.

63. The method according to claim 41, wherein the at least one insulating layer is extrusion-coated.

64. The method according to claim 40, wherein the electric conductor is brought to a temperature of at least 200 C. before the application of the insulating coating.

65. The method according to claim 41, wherein the electric conductor is brought to a temperature of at least 200 C. before the application of the insulating coating.

66. The insulated electric conductor according to claim 1 wherein the electric conductor is made of aluminum or copper.

67. The insulated electric conductor according to claim 5 wherein the electric conductor is made of aluminum or copper.

68. The insulated electric conductor according to claim 6 wherein the electric conductor is made of aluminum or copper.

69. The insulated electric conductor according to claim 21 wherein the electric conductor is made of aluminum or copper.

70. The insulated electric conductor according to claim 23 wherein the electric conductor is made of aluminum or copper.

71. The insulated electric conductor according to claim 24 wherein the electric conductor is made of aluminum or copper.

72. The method according to claim 39 wherein the electric conductor is made of aluminum or copper.

73. The method according to claim 40 wherein the electric conductor is made of aluminum or copper.

74. The method according to claim 41 wherein the electric conductor is made of aluminum or copper.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0076] The invention will now be explained in more detail below with reference to exemplary embodiments. The drawings are provided by way of example and are intended to explain the concept of the invention, but shall in no way restrict it or even render it conclusively, wherein:

[0077] FIG. 1 shows a schematic representation of a method according to the invention;

[0078] FIG. 2a shows a first embodiment variant of an insulated electric conductor with a rectangular cross-section;

[0079] FIG. 2b shows a second embodiment variant of an insulated electric conductor with a rectangular cross-section.

[0080] FIG. 2c shows a third embodiment variant of an insulated electric conductor with a rectangular cross-section;

[0081] FIGS. 3a-3c show the first to third embodiment variant with a round cross-section.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0082] FIG. 1 shows a schematic representation of a method for producing an insulated electric conductor, as shown in FIGS. 2a to 2d and 3a to 3d. The insulated electric conductor comprises an electric conductor 1 made of copper, wherein other materials such as aluminum are conceivable, and an insulating coating 2, which has at least one insulating layer 3 made of thermoplastic material (also called thermoplastic resin, thermoplastic synthetic material or thermoplastic polymer), preferably a high-temperature-resistant plastic. In the following exemplary embodiments, the at least one insulating layer 3 is formed as an outer insulating layer 3 and thus forms the outermost layer of the insulating coating 2. It is understood, however, that in alternative embodiment variants still one or more further layers, preferably insulating layers, may be applied to the insulating layer 3, which can then form the outermost layer of the insulating coating 2.

[0083] The electric conductor 1 is continuously supplied in the illustrated embodiment as a band or wire via a coil outlet 7 to the process and can be prepared for example by means of cold forming processes, such as drawing or rolling, or extrusion, for example by means of Conform technology. It goes without saying that the method according to the invention can also be carried out in-line, i.e. directly connected to the production process. In a first step, the electric conductor 1 is pre-cleaned mechanically in a pre-cleaning unit 8, for example by means of a grinding process, or chemically, for example by means of suitable solvents or acids, in order to remove coarse soiling from the electric conductor 1.

[0084] In the next method step, the pre-cleaned electric conductor 1 enters a plasma treatment unit 9 in which a protective gas atmosphere of nitrogen, argon or hydrogen is present and a gas plasma in the form of a low-pressure plasma is produced with less than 20 mbar pressure. However, a low-pressure plasma can already be produced even at a pressure of less than 80 mbar. In this low-pressure plasma, the surface of the electric conductor 1 is bombarded with ions of the protective gas in order to carry off or remove an oxide layer formed on a surface of the electric conductor 1. At the same time, the electric conductor 1 is soft-annealed by the plasma treatment and the surface energy of the electric conductor 1 therefore increases, thus activating the surface.

[0085] By removing the oxide layer and any contaminants from the surface of the electric conductor 1, wherein it may even be provided that very thin layers of the electric conductor 1 itself are removed from the surface, and by the increase of the surface energy, the adhesion between the electric conductor 1 made of copper and the insulating coating 2 applied to the electric conductor 1 can be improved decisively.

[0086] In the first embodiment variant of the insulated electric conductor according to the invention, shown in FIG. 2a as a flat conductor with a rectangular cross-section and, in FIG. 3a with a round cross-section, the insulating coating 2 consists only of an insulating layer 3. The insulating layer 3 has a temperature resistance of more than 180 C., preferably above 220 C., so that the insulated electric conductor can be used even at high operating temperatures. The outer insulating layer 3 consists of polyetheretherketone [PEEK], which has both high temperature resistance and high resistance to a large number of organic and inorganic substances. Alternatively, the outer insulating layer 3 may also consist of polyphenylene sulfide [PPS] or comprise PEEK and/or PPS.

[0087] In order to achieve the increased adhesion between the electric conductor 1 and the outer insulating layer 3, the electric conductor 1 reaches the extrusion unit 11 after passing through the plasma treatment unit 9, in which the outer insulating layer 3 is extrusion-coated onto the electric conductor 1. In this case, the electric conductor 1 is preheated to a temperature of at least 200 C., preferably at least 300 C. In order to prevent the re-formation of an oxide layer, both the extrusion and the transport of the conductor 1 into the extrusion unit 11 takes place under a protective gas atmosphere. An insulated electric conductor produced in this way can be used, for example, as a winding wire, which is also known in English as a magnet wire, in an electric machine, such as an electric motor or a transformer. The thickness of the outer insulating layer 3 is about 30 m in the present exemplary embodiment.

[0088] In particular, when the insulating layer 3 consists of a polyaryletherketone [PAEK], such as polyetheretherketone [PEEK], particularly good adhesion properties are achieved. Thus, the detachment of the insulating layer 3 from the electric conductor 1 usually remains well below 1 mm, and is in particular at most 0.2 mm, preferably at most 0.1 mm, more preferably at most 0.05 mm, particularly preferably at most 0.01 mm. Even if the thermoplastic material of the insulating layer 3 is polyimide [PI], polyamideimide [PAI], polyetherimide [PEI], polyphenylene sulfide [PPS], increased adhesion properties can be achieved.

[0089] In general, the at least one insulating layer 3 may also comprise two, three, four or more individual insulating layers 3, all of which are produced under a protective gas atmosphere in the extrusion unit 11. As a result, the probability of defects in the insulating coating 2 can be drastically reduced, since defects in the lowermost of the insulating layers 3 are compensated by subsequent insulating layers 3. Tandem extrusion processes are particularly suitable for such a preparation.

[0090] Additionally or instead, it may also be provided that further insulating layers, which are preferably constructed analogously to the at least one insulating layer 3, i.e. in particular of a polyaryletherketone [PAEK] such as polyetheretherketone [PEEK] or another of the aforementioned plastics, are applied to the insulating coating 2 outside the protective gas atmosphere in a further extrusion unit 12.

[0091] In order to increase the adhesion between the insulating coating 2 and the electric conductor 1 as an alternative to the first embodiment variant, the insulating coating 2 comprises in the second embodiment shown in FIGS. 2b and 3b, in addition to the outer insulating layer 3 made of PEEK or PPS, a plastic-containing intermediate layer in form of a plasma polymer layer 4. This plasma polymer layer 4 is produced in the method according to the invention in a plasma polymerization unit 10, which is arranged after the plasma treatment unit 9 and before the extrusion unit 11. It is also conceivable that the plasma treatment and the plasma polymerization are carried out in a combined device. In the plasma polymerization unit 10, after the oxide layer is removed and surface energy increased, as above, the plasma polymer layer 4 is formed on the surface of the electric conductor 1 by activating a gaseous monomer such as ethylene, butenol, acetone or tetrafluoromethane [CF.sub.4] by the plasma and thereby forming highly cross-linked macromolecules of different chain length and a proportion of free radicals, which deposit as a plasma polymer layer 4 on the surface of the electric conductor 1. In the present exemplary embodiment, the resulting plasma polymer layer 4 is less than 1 m thick and adheres particularly well to the activated and oxide-free surface of the electric conductor 1.

[0092] The outer insulating layer 3 is in turn extruded in the extrusion unit 11 onto the plasma polymer layer 4 as described above, wherein the adhesion between the plasma polymer layer 4 and the outer insulating layer 3 is also high.

[0093] In the third embodiment variant, illustrated in FIGS. 2c and 3c, the insulating coating 2 comprises, in addition to the outer insulating layer 3 made of PEEK, a plastic-containing intermediate layer formed as a fluoropolymer layer 5 of polytetrafluoroethylene [PTFE] or perfluoroethylene propylene [FEP], which is applied directly to the surface of the electric conductor 1 and further improves the adhesion between the electric conductor 1 and the outer insulating layer 3. The fluoropolymer layer 5 is produced together with the outer insulating layer 3 in the extrusion unit 11 by means of a co-extrusion or tandem extrusion process. The thickness of the fluoropolymer layer 5 is about 30 m in the present embodiment.

[0094] After extrusion-coating the outer insulating layer 3, the insulated electric conductor is cooled in a controlled manner, for example by air cooling, and passed over a series of pressure rollers which further improve adhesion by applying pressure to the insulated electric conductor. Finally, the insulated electric conductor is wound on a coil winder 13.

[0095] The illustrated devices in FIG. 1 concern an overview in which all devices are shown, which are necessary for the production of the individual embodiment variants. While the sequence, from right to left, of the devices passed through are independent of the embodiment variant and in any case the plasma treatment unit 9 and the extrusion unit 11 have to be passed, the plasma polymerization unit 9 and the further extrusion unit 12 are optional devices which are used only in the production of specific design variants. It is understood that instead of a co-extrusion or tandem extrusion process, several individual extrusions can be carried out sequentially.

LIST OF REFERENCE NUMERALS

[0096] 1 Electric conductor [0097] 2 Insulating coating [0098] 3 Insulating layer [0099] 4 Plasma polymer layer [0100] Fluoropolymer layer [0101] 6 Metal layer [0102] 7 Coil outlet [0103] 8 Precleaning unit [0104] 9 Plasma treatment unit [0105] 10 Plasma polymerization unit [0106] 11 Extrusion unit [0107] 12 Further extrusion unit [0108] 13 Coil winder