Patent Description:
Heating elements for electrothermal deicers typically use etched alloys. The etching process can have an effect on material properties of a component, such as the mechanical properties, or the like. The etching process may remove metal from the surface of a part, which may have an effect on dimensional tolerances or the like. Additionally, chemical etching may be difficult to automate and/or may have waste disposal issues. Conductive inks are described in <CIT>, <CIT>, <CIT>, <CIT> and <CIT>.

In particular <CIT> discloses a conductive ink comprising a high melting temperature thermoplastic polyurethane, the high melting temperature thermoplastic polyurethane including a melting point between <NUM> and <NUM>, a plurality of conductive particles disposed in the high melting temperature thermoplastic polyurethane, the plurality of conductive particles comprising between <NUM>% and <NUM>% by weight of the conductive ink, a crosslinker and an additive.

A conductive ink is provided as defined by claim <NUM>.

The free radical crosslinker may include peroxide. The plurality of conductive particles may include at least one of silver platelet particles and nanosilver. The plurality of conductive particles may include carbon nanotubes (CNT).

A heating trace assembly is provided as defined by claim <NUM>.

In various embodiments, the ceramic PTC element is a thin film of ceramic PTC. The plurality of conductive particles may include at least one of silver platelet particles and nanosilver. The insulator may include a first flexible substrate. The ceramic PTC element may be coupled to the first flexible substrate by an adhesive. The insulator may include a second flexible substrate, and the first bus bar and the second bus bar may be coupled to the second flexible substrate by an adhesive. The insulator may include a first flexible substrate, and the first bus bar and the second bus bar may be coupled to the first flexible substrate by an adhesive.

A method of manufacturing a conductive ink is provided as defined by claim <NUM>.

In various embodiments, the plurality of conductive particles, and wherein curing further comprises heating the resultant mixture.

A more complete understanding of the present disclosure, however, may best be obtained by referring to the detailed description and claims when considered in connection with the following illustrative figures. In the following figures, like reference numbers refer to similar elements and steps throughout the figures.

The detailed description of exemplary embodiments herein makes reference to the accompanying drawings, which show exemplary embodiments by way of illustration. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosures, it should be understood that other embodiments may be realized and that logical changes and adaptations in design and construction may be made in accordance with this disclosure and the teachings herein.

The scope of the disclosure is defined by the appended claims rather than by merely the examples described. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Also, any reference to tacked, attached, fixed, coupled, connected or the like may include permanent, removable, temporary, partial, full and/or any other possible attachment option.

Disclosed herein is a conductive ink for enhanced mechanical fatigue resistance. The conductive ink may comprise conductive particles and a high melting temperature polyurethane (TPU). In various embodiments, the conductive ink may further comprise a free radical crosslinker, such as peroxide The conductive ink may be configured for greater fatigue resistance performance in bending cycle fatigue tests.

With reference to <FIG>, an aircraft <NUM> is provided with a fuselage <NUM>, a left side wing <NUM> and a right side wing <NUM>. The left side wing <NUM> and right side wing <NUM> are designed to provide lift to the aircraft and enable it to fly. The fuselage <NUM> may house passengers, as well as various components configured to operate aircraft <NUM>. In various embodiments, the fuselage <NUM> may comprise a water system <NUM>. Water system <NUM> may be a potable water system, a gray water system, or the like. Water system <NUM> may be disposed in an area of fuselage <NUM> that is susceptible to outside temperature control. As such, at high altitudes, water system <NUM> may be exposed to temperatures below freezing. Water system may be temperature controlled by an internal heating trace assembly.

Referring now to <FIG>, a schematic view of a portion of a water system <NUM> for use on an aircraft <NUM>, in accordance with various embodiments, is illustrated. The water system <NUM> comprises a first tube <NUM>, a second tube <NUM>, an electrical interface <NUM>, and an internal heating trace assembly <NUM>. The first tube <NUM> may comprise a wye shape, a tee shape, or the like. The first tube <NUM> may comprise a water inlet <NUM>, a water outlet <NUM>, and a heating trace inlet <NUM>. The second tube <NUM> may comprise a water inlet <NUM> and a water outlet <NUM>. The water inlet <NUM> of the second tube <NUM> may be coupled to the water outlet <NUM> of the first tube <NUM> by any method known in the art. For example, water inlet <NUM> of the second tube <NUM> may be coupled to the water outlet <NUM> of the first tube <NUM> by a coupling <NUM>, such as two-ferrule fitting, a single ferrule fitting, a ferrule-less push-fit connector, a collar fitting, or the like. The water system <NUM> may flow in a first direction B from water inlet <NUM> from first tube <NUM> through water outlet <NUM> of second tube <NUM>.

In various embodiments, electrical interface <NUM> is disposed at the heating trace inlet <NUM> of the first tube <NUM>. The electrical interface <NUM> may be any electrical interface <NUM> known in the art, such as a junction box or the like. The electrical interface <NUM> may be in electrical communication with a controller and/or a monitoring system. The electrical interface <NUM> is coupled to the internal heating trace assembly <NUM>. The internal heating trace assembly <NUM> is in electrical communication with the electrical interface <NUM>. A first end <NUM> internal heating trace assembly <NUM> is fixed at the electrical interface <NUM> and the second end <NUM> is free within the water system <NUM>. For example, second end <NUM> may be free in second tube <NUM> or an upstream tube in water system <NUM>. The internal heating trace assembly <NUM> may be configured to control a temperature of water disposed in water system <NUM> during normal operation. In various embodiments, bus wires disposed in the internal heating trace assembly <NUM> may conduct current from the electrical interface <NUM> through the length of the internal heating trace assembly <NUM> during normal operation.

Although water system <NUM> is disclosed with respect to an aircraft <NUM>, any water system with temperature control is within the scope of this disclosure.

Referring now to <FIG>, a cross-sectional view of internal heating trace assembly <NUM> along section A-A from <FIG>, in accordance with various embodiments, is illustrated. Internal heating trace assembly <NUM> comprises a ceramic Positive Temperature Coefficient (PTC) element <NUM>, a first bus bar <NUM>, a second bus bar <NUM>, and an insulator <NUM>. In various embodiments, the ceramic PTC element <NUM> may extend along the length of the internal heating trace assembly <NUM>. The ceramic PTC element <NUM> may be disposed between, and coupled to, the first bus bar <NUM> and the second bus bar <NUM>. In various embodiment, the ceramic PTC element is in electrical communication with the first bus bar <NUM> and the second bus bar <NUM>. The first bus bar <NUM> and the second bus bar <NUM> may be any conductive element known in the art. For example, the first bus bar <NUM> and the second bus bar <NUM> may be a conductive ink as disclosed herein. The first bus bar <NUM> and the second bus bar <NUM> may be electrically coupled to the electrical interface <NUM> from <FIG>. The first bus bar <NUM> and the second bus bar <NUM> may be configured to carry an electrical current in internal heating trace assembly <NUM>.

In various embodiments, insulator <NUM> is disposed around the first bus bar <NUM>, the second bus bar <NUM>, and the ceramic PTC element <NUM>. The insulator <NUM> may be any electrical insulator known in the art (e.g., polyethylene, cross linked polyethylene-XLPE, polyvinyl chloride PVC, Teflon, silicone, polyolefin, fluoropolymer, etc.). The insulator <NUM> may be configured to insulate the electricity generated from the first bus bar <NUM>, the second bus bar <NUM>, and the ceramic PTC element <NUM> from the water disposed in water system <NUM> from <FIG>.

In various embodiments, an adhesive is disposed between the insulator <NUM> and the ceramic PTC element <NUM>. In various embodiments, an adhesive is disposed between the insulator <NUM> and the first bus bar <NUM> and the second bus bar <NUM>. The insulator <NUM> may include a first flexible substrate <NUM>. In various embodiments, when the first bus bar <NUM> and the second bus bar <NUM> are conductive inks, the conductive inks are deposited on the first flexible substrate <NUM> running down the length of the flexible substrate <NUM>. The first bus bar <NUM> and the second bus bar <NUM> are a thermoset-based ink, such as a silver conductor sold under the trademark DuPont® <NUM> which is available from DuPont of Midland, Michigan, a conductor sold under the trademark Loctite® ECI <NUM> E&C which is available from Henkel Corporation of Dusseldorf, Germany. In various embodiments, the ceramic PTC element <NUM> may include a thin film of ceramic PTC. In various embodiments, the thin film of ceramic PTC may be printed on the second flexible substrate <NUM> along the length of the second flexible substrate <NUM>. In various embodiments, a liquid closeout may be coated on the second substrate <NUM> prior to printing the ceramic PTC element <NUM> and cured after the ceramic PTC element <NUM> is printed on the second substrate <NUM>. In various embodiments, a solid film closeout of the PTC element <NUM> is bonded on with adhesive.

Referring now to <FIG>, a schematic view of a portion of a water system <NUM> for use on an aircraft <NUM>, in accordance with various embodiments, is illustrated. The water system <NUM> comprises a tube <NUM>, an electrical interface <NUM>, and a heating trace assembly <NUM>. The tube <NUM> may be configured to carry a fluid, such as gray water, or the like. The tube <NUM> may comprise a water inlet <NUM> and a water outlet <NUM>. The water system <NUM> may flow in a first direction C from water inlet <NUM> from tube <NUM> through water outlet <NUM> of tube <NUM>.

In various embodiments, electrical interface <NUM> is disposed proximate the tube <NUM>. The electrical interface <NUM> may be any electrical interface <NUM> known in the art, such as an electrical connector or the like. The electrical interface <NUM> may be in electrical communication with a controller and/or a monitoring system. The electrical interface <NUM> is coupled to the heating trace assembly <NUM>. The heating trace assembly <NUM> is in electrical communication with the electrical interface <NUM>. A first end <NUM> internal heating trace assembly <NUM> is fixed at the electrical interface <NUM> and the second end <NUM> is fixed to an outer surface of tube <NUM>. For example, second end <NUM> may be fixed to the outer surface of tube <NUM> by any method known in the art, such as an adhesive or the like. The heating trace assembly <NUM> may be configured to control a temperature of water disposed in water system <NUM> during normal operation. In various embodiments, bus wires disposed in the heating trace assembly <NUM> may conduct current from the electrical interface <NUM> through the length of the heating trace assembly <NUM> during normal operation.

Referring now to <FIG>, a cross-sectional view of heating trace assembly <NUM> coupled to an outer surface of a tube, in accordance with various embodiments, is illustrated. Heating trace assembly <NUM> comprises a ceramic PTC element <NUM>, a first bus bar <NUM>, a second bus bar <NUM>, and an insulator <NUM>. In various embodiments, the ceramic PTC element <NUM> may extend along the length of the heating trace assembly <NUM>. The ceramic PTC element <NUM> may be disposed between, and coupled to, the first bus bar <NUM> and the second bus bar <NUM>. In various embodiment, the ceramic PTC element is in electrical communication with the first bus bar <NUM> and the second bus bar <NUM>. The first bus bar <NUM> and the second bus bar <NUM> may be any conductive element known in the art. For example, the first bus bar <NUM> and the second bus bar <NUM> may be a conductive ink as disclosed herein. The first bus bar <NUM> and the second bus bar <NUM> may be electrically coupled to the electrical interface <NUM> from <FIG>. The first bus bar <NUM> and the second bus bar <NUM> may be configured to carry an electrical current in internal heating trace assembly <NUM>.

In various embodiments, insulator <NUM> is disposed around the first bus bar <NUM>, the second bus bar <NUM>, and the ceramic PTC element <NUM> and coupled to an outer surface <NUM> of tube <NUM>. The insulator <NUM> may be any electrical insulator known in the art (e.g., polyethylene, cross linked polyethylene-XLPE, polyvinyl chloride PVC, polytetrafluorethylene (PTFE), silicone, polyolefin, fluoropolymer, etc.). The insulator <NUM> may be configured to insulate the electricity generated from the first bus bar <NUM>, the second bus bar <NUM>, and the ceramic PTC element <NUM> from external components in water system <NUM> from <FIG>.

Referring now to <FIG>, a conductive ink <NUM>, in accordance with various embodiments, is illustrated. The conductive ink <NUM> may be configured for enhanced mechanical fatigue resistance. In various embodiments, first bus bar <NUM> and second bus bar <NUM> may comprise conductive ink <NUM>. Although described with respect to an internal heating trace assembly <NUM>, conductive ink <NUM> may be used for rotor blades and/or fixed wing electrothermal ice protection. For example, conductive ink <NUM> may be utilized as a bus bar for an electrothermal ice protection system in a rotor blade and/or fixed wing. By utilizing the conductive ink <NUM>, the ice protection system may be more robust (i.e., the conductive ink may provide mechanical fatigue resistance during vibration of the rotor blade or fixed wing).

The conductive ink comprises a high melting temperature thermoplastic polyurethane (TPU) <NUM> and a plurality of conductive particles <NUM>. A "high melting temperature TPU," as disclose herein is a TPU with a melting point between <NUM> (<NUM> °F) and <NUM> (<NUM> °F), or between <NUM> (<NUM> °F) and <NUM> (<NUM> °F), or between <NUM> (<NUM> °F) and <NUM> (<NUM> °F). In various embodiments, the high melting temperature TPU may be any high melting temperature TPU known in the art, such as that sold under the trademark Pearlbond® <NUM> EXP, Pearlbond® 95AB0 NAT, <NUM> Pearlbond® HMS EXP which is available from Lubrizol of Wickliffe, Ohio, USA, IROGRAN® A <NUM> P <NUM> which is available from Huntsman Corporation of The Woodlands, Texas, USA, ELASTOLLAN® <NUM> A <NUM> HPM polyester, or the like.

In various embodiments, the plurality of conductive particles <NUM> may be any conductive particles known in the art. For example, the plurality of conductive particles may comprise silver particles, silver platelet particles, nanosilver, or any combination of the three. In various embodiments, the plurality of conductive particles <NUM> may comprise carbon nanotubes (CNT) graphene, or the like.

Referring now to <FIG>, a conductive ink <NUM>, in accordance with various embodiments, is illustrated. The conductive ink comprises mixture <NUM> and a plurality of conductive particles <NUM>. In various embodiments, the mixture <NUM> includes a high melting temperature thermoplastic polyurethane (TPU) and a free radical cross linker, such as peroxide. In various embodiments, the conductive particles <NUM> may be disposed within the urethane elastomer.

In various embodiments, the conductive inks <NUM>, <NUM> may comprise the plurality of conductive particles <NUM> in an amount of <NUM>% to <NUM>%, or between <NUM>% and <NUM>% by weight of the conductive ink. In various embodiments, when the conductive particles comprise CNT, the amount of CNT particles may be between <NUM>% and <NUM>%.

In various embodiments, the conductive inks <NUM>, <NUM> may show provide enhanced fatigue resistance performance in four point bending cycle fatigue tests compared to chemical etching, or the like. The conductive inks <NUM>, <NUM> may be used for external heated composite structures, such as rotor blades, fixed wings, faring, engine lip electrothermal ice protection, or the like.

Referring now to <FIG>, a method <NUM> for manufacturing a conductive ink, in accordance with various embodiments, is illustrated. The method <NUM> comprises mixing a high melting temperature TPU with a plurality of conductive particles (step <NUM>). In various embodiments, the mixing may further comprise mixing a free radical crosslinker, such as peroxide. The mixture may be in accordance with conductive inks <NUM>, <NUM>, as disclosed above. The method may further comprise curing the mixture of high melting temperature TPU with the plurality of conductive particles (step <NUM>). In various embodiments, the curing may comprise heating the mixture, resulting in crosslinking between the high melting temperature TPU and the free radical crosslinker. In various embodiments, the curing may comprise adding an additive which acts as a reinforcing agent and an adhesive promoter, such as titanium dioxide particles.

However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the disclosures. The scope of the disclosures is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean "one and only one" unless explicitly so stated, but rather "one or more.

Claim 1:
A conductive ink, comprising:
a high melting temperature thermoplastic polyurethane, TPU, the high melting temperature TPU including a melting point between <NUM> (<NUM> °F) and <NUM> (<NUM> °F);
a plurality of conductive particles (<NUM>) disposed in the high melting temperature TPU, the plurality of conductive particles comprising between <NUM>% and <NUM>% of the conductive ink by weight;
a free radical crosslinker; and
an additive configured to act as a reinforcing agent and an adhesive promoter, the additive including titanium dioxide particles.