Patent Application
20150093573
Not applicable
Not applicable
1. Technical Field
The present disclosure relates generally to self-bonding conductive wire. More particularly, the present disclosure relates to the use of polyester polyether block copolymers in self-bonding wire, and methods of making and using such wire.
2. Related Art
In the use of conductive wire, it is common that wire may be placed into specific configurations as desired by a user, such as wrapping the wire into coils. Once the wire has been placed into a desired configuration, it becomes necessary to secure the wire in that configuration. This securing may maintain the integrity of the chosen wire configuration, and ensure that the individual wires do not become loose, noisy, or subject to early failure through vibrations and other movement. Securing wire is especially important when the wire is shaped into self-supporting or unusual configuration, such as bobbin-less coils.
Many conventional ways have been developed to secure wire. In the past, wire has been coated with a liquid or viscous varnish, which hardens following the coating step to maintain the wire's configuration. It was later found that wires may be made with outer coatings which may self-adhere or self-bond, eliminating the requirement for a varnishing step.
Various outer coatings have been used which may confer self-adhering or self-bonding properties to wire. Typically, self-bonding is achieved by softening or melting the coating and then allowing the coating to resolidify and fuse. The softening or melting may be performed by application of heat, electricity, or a suitable solvent. However, previously used outer coatings suffer from various deficiencies, such as sharp reductions in melting point, modulus, tensile strength, and elasticity following resolidification and fusion.
Consequently, there is a need for an improved self-bonding conductive wire.
To solve these and other problems, it is contemplated that a polyester polyether block copolymer material may be used to form a self-bonding coating over a conductive wire, in order to confer superior self-bonding properties to that wire. Particularly, it is contemplated that the polyester polyether block copolymer material may have a durometer hardness (Type D) measured according to ISO 868 of about 30. Such material may be made by known methods of synthesis, or may be obtained commercially from manufacturers such as E.I. DuPont de Nemours and Co., Inc.
The self-bonding conductive wire may comprise a conductor and a covering disposed over the conductor formed of a polyester polyether block copolymer. The polyester polyether block copolymer may have a durometer hardness (Type D) measured according to ISO 868 of about 30.
The conductive wire may also have an insulator disposed between the conductor and the covering. The insulator may comprise one or more layers of insulation disposed between the conductor and the covering. The one or more layers of insulation may be a fluoropolymer. The fluropolymer may be an ethylene/tetrafluoroethylene copolymer.
Such a conductive wire may be made by disposing an insulator over a conductor, and applying a covering over the insulator comprising a polyester polyether block copolymer. The steps of applying the insulation material and the polyester polyether block copolymer covering may be accomplished by extrusion through an extrusion crosshead.
Such a conductive wire may be used by configuring the wire into a desired configuration, and applying energy to the covering to allow it to thermoplastically deform. The energy may be applied in the form of heat, such as with an oven or heat gun, or in the form of an electric current or chemical reaction.
These and other features and advantages of the various embodiments disclosed herein will be better understood with respect to the following description and drawings, in which:
Common reference numerals are used throughout the drawings and the detailed description to indicate the same elements.
According to various aspects of the present invention, a new type of self-bonding conductive wire and a related method of using a self-bonding conductive wire is contemplated, which utilizes a self-bonding outer coating comprising a polyester polyether block copolymer. The wire includes a conductor and a self-bonding outer coating over the conductor, and is formed into the desired configuration of the user, such as in a bobbin-less coil or other self-supporting configuration. Subsequently, an energy source such as heat from an oven or heat gun is used to soften the polyester polyether block copolymer of the self-bonding outer coating. Consequently, the self-bonding outer coating associates with the self-bonding outer coating of adjacent strands of wire. The wire may then be removed from the energy source, allowing the self-bonding outer coating to harden, resulting in a bonded outer coating which attaches adjacent strands of wire to one another. It is additionally contemplated that the polyester-polyether block copolymer have a durometer hardness (Type D) measured according to ISO 686 of about 30, such as those which may be obtained commercially from polymer manufacturers such as E.I. DuPont de Nemours and Co. Inc. It is further contemplated that one or more layers of insulation may be disposed between the conductor and the self-bonding outer coating, and that the insulator may be an ethylene/tetraflouroethylene (“ETFE”) copolymer.
Referring now to the drawings, and more particularly to
Referring now to
The conductor 14 may be any conductive material usable in the making and using of conductive wire. For example, but without limitation, the conductor 14 may be a conductive metal such as copper, silver, or aluminum However, it may also be seen that the conductor 14 may not only be limited to electrically conductive materials, but may also include other signal conductors or transmitters, including but not limited to fiber optics, waveguides, or lasing mediums. Further, it may be seen that the conductor 14 may comprise a single wire of conductive material, or may also be a plurality of wires of conductive material as shown in the exemplary embodiment. Such a plurality of wires of conductive material may allow, for example, multiple signals to be conveyed over a single self-bonding conductive wire, or for greater flexibility, kink-resistance, and break-resistance in the self-bonding conductive wire 10.
The insulator 16 may be any insulative material useable in conductive wire. In the exemplary embodiment, the insulator 16 is a fluoropolymer, and more specifically, an ETFE copolymer. However, it may also be seen that the insulator 16 may be, for example but without limitation, other insulation materials known in the art and usable in conductive wire, such as silicon rubber or fiber reinforced plastic. The insulator 16 may comprise a single layer of insulative material, or multiple layers of insulative material. In the exemplary embodiment, a single layer of insulation is shown, but multiple layers of insulation comprising the same or different insulation material may also be used without departing from the scope of the present disclosure.
The self-bonding outer coating 18 may comprise a polyester polyether block copolymer. In the exemplary embodiment, the self-bonding outer coating 18 is a polyester polyether block copolymer having a durometer hardness (Type D) measured according to ISO 868 of about 30. Such a polyester polyether block copolymer may be synthesized by methods known in the art. For example, a polyester-polyether block copolymer may be synthesized with a narrow molecular weight distribution and chain length according to the methods described by Yasuda, Aida and Inoue in their article Synthesis of Polyester-Polyether Block Copolymer with Controlled Chain Length from β-Lactone and Epoxide by Aluminum Porphyrin Catalyst, published in Macromolecules 1984, 17, 2217-2222. The polyester polyether block copolymer may also be obtained commercially from companies such as E.I. DuPont de Nemours and Co. Inc., as sold under the trade name Hytrel®. The polyester polyether block copolymer of the exemplary embodiment in particular has a durometer hardness (Type D) measured according to ISO 868 of about 30, which corresponds to DuPont's Hytrel® 3078 commercial product.
Other qualities of the polyester polyether block copolymer used in the exemplary embodiment include the following:
However, it may be seen that the polyester polyether block copolymer used may vary in, for example but without limitation, molecular weight and chain length. Such variations may result in variations in the observable properties of the self-bonding outer coating 18 from those listed above, without departing from the scope of the present disclosure.
The use of a polyester polyether block copolymer to form the self-bonding outer coating 18, as in the exemplary embodiment, may have particular advantages, including a resistance to the degradation of material qualities pertinent to the structural integrity of the outer coatings of conductive wire. Such material properties may include melting point, modulus, tensile strength, and elasticity. It may be seen that in conventional self-bonding materials, or even in thermoplastic materials including random copolymers, thermoplastic softening may result in sharp reductions in these qualities following resolidification. The use of a polyester polyether block copolymer may, however, strongly mitigate these sharp reductions, as well as provide strong resistance to deterioration from many industrial chemicals, oils and solvents, and the necessary flexibility required in a wire application, due to the unique characteristics of the polyester polyether block copolymer.
Referring now to
Such application of energy may include, for example, but without limitation, heat from a heat gun or oven, electricity, or chemical energy from a chemical reaction. However, it may be seen that any application of energy which may cause the polyester polyether block copolymer of the self-bonding outer coating 18 to thermoplastically deform and self-bond may be utilized. In one particular exemplary method, a user may place a formed coil 12 into an oven for a period of time suitable for the self-bonding outer coating 18 to self-bond. However, it may also be seen that in other configurations, it may be preferable to apply heat to only particular portions of the formed self-bonding conductive wire 10, such as those portions which are self-contacting. In those situations, a heat gun may be a preferred method of applying energy to the self-bonding outer coating 18.
Referring now to
With the structural features of the self-bonding conductive wire 10 described above, the following discussion concerns methods of making and using the self-bonding conductive wire 10 according to other aspects of the present invention. Such a self-bonding conductive wire 10 as described above may be made by any methods known in the art of making conductive wire. One of these methods may be, for example, passing a conductor 14 through a series of extrusion crossheads. The initial extrusion crosshead may, in one particular embodiment, coat the conductor 14 with a resinous insulator 16 such as a fluropolymer like ETFE. It may be seen that repeating the flowing of the conductor though the same or other extrusion crossheads may result in additional coatings of resinous materials, such as extra layers of insulation. The final extrusion crosshead may coat the conductor 14 and any materials disposed over the conductor by previous coatings, such as an insulator 16, with a self-bonding outer coating 18 comprising a polyester polyether block copolymer.
To use the self-bonding conductive wire 10 as described above, a user may first form the self-bonding conductive wire 10 into a desired configuration. Following this forming, the user may then apply energy sufficient to cause the polyester polyether block copolymer of the self-bonding outer coating 18 to thermoplastically deform. Such application of energy may be accomplished by, for example but without limitation, the application of heat through an oven or heat gun, or the application of electrical current or chemical energy. The user may then remove the energy source, and allow the self-bonded outer coating 18 to solidify, resulting in the fusion of the self-bonding outer coating 18 around strands of wire positioned proximally prior to the application of energy.
The above description is given by way of example, and not limitation. Given the above disclosure, one skilled in the art could devise variations that are within the scope and spirit of the invention disclosed herein, including various types of conductors 14, insulators 16, or methods of applying energy to the self-bonding outer coating 18. Further, the various features of the embodiments disclosed herein can be used alone, or in varying combinations with each other and are not intended to be limited to the specific combination described herein. Thus, the scope of the claims is not to be limited by the illustrated embodiments.
