Dual function powder charging and dispersion system

Abstract

A dual function powder charging and dispersion system for powder coating is provided. The system includes a powder particle chamber configured to receive powder particles. The system includes a dispersion section configured to receive the powder particles from the powder particle chamber. The system includes a power supply electrically connected to the dispersion section to supply a current to at least one structure within the dispersion section such that the at least one structure serves as a charging element for charging of the powder particles within the dispersion section. The dispersion section acts as a means for both charging the powder particles within the dispersion section with the charging element, and dispersing or dispensing charged powder particles from the dispersion section onto a substrate.

Description

DUAL FUNCTION POWDER CHARGING AND DISPERSION SYSTEMCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of a co-pending, commonly assigned U.S. Provisional Patent Application No. 63 / 617,842, which was filed on January 5, 2024 The entire content of the foregoing provisional application is incorporated herein by reference.BACKGROUND

[0002] A variety of batteries are available in the industry for different uses. Lithium- ion (Li-ion) batteries have generally become the predominant type of battery used in portable consumer electronics and electric vehicles. Fabrication of Li-ion batteries involves numerous steps, each of which can affect the quality of the battery itself, as well as the cost involved in manufacturing the battery. A conventional manufacturing process generally includes formation of an electrode slurry having an active material, a conductive additive, and a binder, mixed in an organic solvent, and the electrode slurry is applied to a metal foil material. Once applied to the foil material, the solvent is dried out or evaporated while the active electrode mixture remains attached to the metal foil material surface. In some instances, the solvent may be toxic and can necessitate additional steps for handling / discarding that increase the overall cost of the manufacturing process. The cost of removing the solvent from the coated material on the metal foil therefore involves an additional step that also increases the overall cost of the manufacturing process.

[0003] An alternative manufacturing technique used in the industry is electrostatic deposition (ESD), which is a solvent-free manufacturing process for electrode coating for Li-ion batteries. See, e.g., B. Ludwig et al., Solvent-Free Manufacturing of Electrodes for Lithium-ion Batteries, Sci. Rep. 6, Article No. 23150, doi: 10.1038 / srep23150 (2016); M. Wang et al., The Influence of Polyvinylidene Fluoride (PVDF) Binder Properties on LiNio.33Coo.33Mno.33O2 (NMC) Electrodes Made by a Dry-Powder-Coating Process, J. Electrochem. Soc., Vol. 166, No. 10, A2151 (2019); H. Abe et al., Electrostatic Spray Deposition for Fabrication of Li-ion Batteries, Transactions of JWRI, Vol. 44, No. 2 (2015); and U.S. Patent No. 10,547,044). Rather than relying on a solvent mixture, the ESD process uses a dry powder of the active electrode mixture which is applied to the metal foil material. By removing the solvent from the mixture and the drying step from the manufacturing process, the overall process is simplified and becomes more economical, resulting in a viable alternative for large-scale manufacturing. In particular, the solvent-free electrode coating technology is an attractive alternative to traditional manufacturing since it can significantly reduce energy consumption in the manufacturing process and thus significantly reduces the manufacturing cost of batteries.

[0004] In a conventional continuous dry powder ESD coating system, a web (e.g., a grounded electrically conductive substrate) passes continuously through a coating chamber while the dry powder mixture is fluidized and pneumatically conveyed from a hopper to an electrostatic spray gun. The electrostatic spray gun electrostatically charges the powders using tribo-charging or corona charging, and sprays the charged powders onto the web where they are deposited. In general, tribo-charging and corona charging are the primary methods in the industry to electrostatically charge the powder.

[0005] Direct charging is another electrostatically charging process, although it is typically used less often than tribo-charging and corona charging due to the difficulty in assuring that a large majority of the powder particles contact the conductive charging surface. In direct charging, the particles contact a conductive surface to receive the charge. Difficulty in ensuring that a large percentage of powder particles contact the conductive surface results in a suboptimal charging process. In addition, direct charging systems can encounter practical challenges, such as electromagnetically isolating the charged surfaces from external interference or interfering with surrounding devices / systems.SUMMARY

[0006] Embodiments of the present disclosure provide an exemplary electrostatic deposition coating system that allows for more efficient and effective direct charging of the powder particles. In particular, the exemplary system is a dual function powder charging and dispersion system that applies a voltage (using a voltage source) to a powder dispensing / dispersion system. The system being used for dispensing and / or dispersion of powder particles therefore serves as the conductive element for charging the powder particles. As particles pass through or over the dispensing / dispersion system, the powder particles are charged. The use of the dispensing / dispersion system as the conductive material increases the contact between the conductive material and the particles, thereby increasing the percentage of particles that are charged (e.g., about 50-100% inclusive, 50- 90% inclusive, 50-80% inclusive, 50-70% inclusive, 50-60% inclusive, 60-90% inclusive, 60-80% inclusive, 60-70% inclusive, 60-100% inclusive, 70-100% inclusive, 80-100% inclusive, 90-100% inclusive, 50%, 60%, 70%, 80%, 90%, 100%, or the like).

[0007] In accordance with embodiments of the present disclosure, an exemplary dual function powder charging and dispersion system for powder coating is provided. The system includes a powder particle chamber configured to receive powder particles. The system includes a dispersion section configured to receive the powder particles from the powder particle chamber. The system includes a power supply electrically connected to the dispersion section to supply a current to at least one structure within the dispersion section such that the at least one structure serves as a charging element for charging of the powder particles within the dispersion section. The dispersion section acts as a means for both charging the powder particles within the dispersion section with the charging element and dispersing or dispensing charged powder particles from the dispersion section onto a substrate.

[0008] In some embodiments, the powder particle chamber can be a hopper with an opening adjacent to the dispersion section. The opening is configured to incrementally release the powder particles into the dispersion section. The system can include an insulation and / or isolation layer between the dispersion section and the powder particle chamber. The system can include an insulation and / or isolation layer between the at least one structure of the dispersion section and the powder particle chamber.

[0009] Contact of the powder particles with the at least one structure within the dispersion section during passage of the powder particles through the dispersion section charges at least a portion of the powder particles prior to dispersing or dispensing of the powder particles from the dispersion section. The at least one structure can be fabricated from a conductive material.

[0010] In some embodiments, the at least one structure of the dispersion section can be a spray nozzle. In some embodiments, the at least one structure of the dispersion section can be a distribution pipe with multiple openings formed therein for dispersing or dispensing of the charged powder particles from the distribution pipe. In some embodiments, the at least one structure of the dispersion section can be a powder extraction mechanism, and the dispersion section can include a powder feeding roller positioned adjacent to the stripping brush. In some embodiments, the at least one structure of the dispersion section can be a scattering roller, and the dispersion section can include a stripping brush positioned adjacent to the scattering roller. In some embodiments, the at least one structure of the dispersion section can be both a scattering roller and a stripping brush positioned adjacent to the scattering roller.

[0011] In accordance with embodiments of the present disclosure, an exemplary system for powder coating is provided. The system includes a substrate configured to move from a proximal end to a distal end of a containment enclosure. The system includes a dual function powder charging and dispersion system disposed adjacent to the substrate. The dual function powder charging and dispersion system includes a powder particle chamber configured to receive powder particles, a dispersion section configured to receive the powder particles from the powder particle chamber, and a power supply electrically connected to the dispersion section to supply a current to at least one structure within the dispersion section such that the at least one structure serves as a charging element for charging of the powder particles within the dispersion section. The dispersion section acts as a means for both charging the powder particles within the dispersion section with the charging element and dispersing or dispensing charged powder particles from the dispersion section onto the substrate.

[0012] The at least one structure can be fabricated from a conductive material. The at least one structure of the dispersion section can be at least one of a spray nozzle, a distribution pipe with multiple openings formed therein, a stripping brush positioned adjacent to a scattering roller, or a scattering roller positioned adjacent to the stripping brush.

[0013] In accordance with embodiments of the present disclosure, an exemplary method of powder coating is provided. The method includes passing powder particles from a powder particle chamber to a dispersion section of a dual function powder charging and dispersion system. The method includes supplying a current to at least one structure within the dispersion section with a power supply electrically connected to the dispersion section such that the at least one structure serves as a charging element. The method includes charging at least a portion of the powder particles within the dispersion section with the charging element. The dispersion section acts as a means for both charging the powder particles within the dispersion section with the charging element and dispersing or dispensing charged powder particles from the dispersion section onto a substrate.

[0014] The system can include an insulation and / or isolation layer disposed between the dispersion section and the powder particle chamber. The system includes an insulation and / or isolation layer disposed between the at least one structure of the dispersion section and the powder particle chamber. Contact of the powder particles with the at least one structure within the dispersion section during passage of the powder particles through thedispersion section charges at least a portion of the powder particles prior to dispersing or dispensing of the powder particles from the dispersion section. The at least one structure can be fabricated from a conductive material. The at least one structure of the dispersion section can be at least one of a spray nozzle, a distribution pipe with multiple openings formed therein, a stripping brush positioned adjacent to a scattering roller, or a scattering roller positioned adjacent to the stripping brush.

[0015] Any combination and / or permutation of embodiments is envisioned. Other objects and features will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed as an illustration only and not as a definition of the limits of the present disclosure.BRIEF DESCRIPTION OF THE DRAWINGS

[0016] To assist those of skill in the art in making and using the dual function powder charging and dispersion system, reference is made to the accompanying figures, wherein:

[0017] FIG. 1 is a diagrammatic view of an exemplary dual function powder charging and dispersion system in accordance with embodiments of the present disclosure.

[0018] FIG. 2 is a diagrammatic view of an exemplary dual function powder charging and dispersion system including a powder extraction mechanism in accordance with embodiments of the present disclosure.

[0019] FIG. 3 is a diagrammatic view of an exemplary dual function powder charging and dispersion system including a scattering roller in accordance with embodiments of the present disclosure.

[0020] FIG. 4 is a diagrammatic view of an exemplary dual function powder charging and dispersion system including a spray nozzle in accordance with embodiments of the present disclosure.DETAILED DESCRIPTION

[0021] FIG. 1 is a diagrammatic view of an exemplary dual function powder charging and dispersion system 100 (hereinafter “system 100”). The system 100 can be used to manufacture a coated substrate usable in, e.g., Li-ion batteries, solid state batteries, or the like. The system 100 can be incorporated into an containment enclosure (e.g., acontainment chamber) for deposition of the powder coating onto a substrate or web 102, e.g., a continuously moving substrate or web 102. The web 102 includes a top surface on which the powder coating is applied. The powder coating includes at least a cathode material or an anode material, e.g., for rechargeable lithium batteries, or the like. In some embodiments, the bottom surface of the web 102 can also receive the powder coating either concurrently with the top surface or subsequent to the top surface being coated. Rollers can be positioned on opposite proximal and distal ends of the web 102 and suspend the web 102 as it passes through the containment enclosure. The rollers can rotate in a combined manner to maintain the continuous movement of the web 102 through the containment enclosure in a web direction 104.

[0022] The system 100 includes a dispersion and / or dispensing section 106. The section 106 can be in the form of, e.g., nozzles, distribution pipes, rollers, scattering wheels, combinations thereof, or the like. The section 106 is positioned adjacent to or offset from the surface of the web 102. The system 100 includes a powder particle source or chamber 108 that feeds powder particles 110 into the section 106. In some embodiments, a fan can be positioned within or adjacent to the powder particle chamber 108 to feed or guide the powder particles 110 into the section 106. It should be understood that any mechanism known in the industry can be used to feed the powder particles 110 into the section 106.

[0023] The system 100 includes a controlled voltage source 112 (e.g., a power source) electrically connected to the section 106 and configured to apply a voltage to the section 106. The voltage can be, e.g., direct current, alternating current, combinations thereof, or the like. In some embodiments, the voltage can be in the range of about, e.g., 500-4,000 V inclusive, 500-3,500 V inclusive, 500-3,000 V inclusive, 500-2,500 V inclusive, 500-2,000 V inclusive, 500-1,500 V inclusive, 500-1,000 V inclusive, 1,000-4,000 V inclusive, 1,500- 4,000 V inclusive, 2,000-4,000 V inclusive, 2,500-4,000 V inclusive, 3,000-4,000 V inclusive, 3,500-4,000 V inclusive, 1,000-3,000 V inclusive, 2,000-3,000 V inclusive, 500 V, 1,000 V, 1,500 V, 2,000 V, 2,500 V, 3,000 V, 3,500 V, 4,000 V, or the like. In particular, the section 106 can define a housing that surrounds internal components 114, with the interna] components 114 performing the dispersing and / or dispensing action of the section 106. The housing of the section 106 is fabricated from a conductive material, and the voltage source 112 is used to apply a voltage to the conductive material. A controller 116 in communication with the voltage source 112 can be used to regulate the amount of voltage being applied to the section 106 housing.

[0024] In some embodiments, the voltage is only applied to the housing of the section 106 such that only the housing acts as the charging element of the system 100. In some embodiments, applying voltage to the section 106 results in at least some of the internal components 114 also acting as charging elements of the system 100 (e.g., in such embodiments, at least a portion of the internal components 114 can be fabricated from a conductive material). For example, the nozzle, roller and / or distribution tube can be fabricated from a conductive material to act as a charging element for the powder particles 110. In some embodiments, only the internal components 114 of the section 106 which provide the dispersing and / or dispensing function of the system 100 receive the current from the voltage source 112 act as the charging element for the powder particles 110. In particular, the structures making contact with the powder particles 110 can be conductive such that voltage is applied to such structures and transferred to the powder particles 110 during contact. Any internal items not making contact with the powder particles 110 can be insulated from the conductive surfaces. For example, the interior of the housing can be conductive and at potential, and the exterior of the housing is coated in insulating and / or shielding layers. Thus, the same structure used for dispersing / dispensing acts as the direct charging element for the system 100.

[0025] The charge of the powder particles 110 can begin to dissipate when the particles 110 make contact with anything having a lower potential than the charged particle 110. As such, the majority (if not all) of the components within the section 106 can act as charging elements to ensure that the powder particles 110 maintain their charge and reach saturation charge. The contact time and / or contact opportunities of the powder particles 110 with the charging element surface can he increased with the system 100 using, e.g., turbulent airflow, or the like, to ensure that a sufficient charge is transferred to the powder particles 110, thereby increasing the effectiveness of the system 100. The contact time can also be increased by extending the charging surfaces to the upstream conveying line surfaces. The contact time and contact opportunities can be varied depending on the conductive nature of the housing and / or the powder particle 110 itself. The contact time is dependent on the powder’s dielectric properties, particle size / morphology, the applied potential, and the available power. For insulative materials such as polymers, the contact time can be on the order of minutes to hours. For semi-conductive materials such as lithium metal oxides, the contact time can be on the order of seconds to minutes. For conductive materials such as conductive carbon, the contact time is on the order of fractions of a second.

[0026] The section 106 is isolated from the environment using, e.g., insulating materials, faraday cage principles, combinations thereof, or the like, to shield the charged powder dispensing system from being impacted and / or from impacting the environment through electrical conduction, electromagnetic induction, and electromagnetic radiation. The isolation or shielding material is referred to herein as an isolation layer 118. In some embodiments, a shielding material can be positioned around the outside of the housing of the section 106 to provide the insulation / shielding effect. In some embodiments, the isolation layer 118 can be a composite sheath, depending on the needs. For example, the sheath can be a composite of an insulating layer, a conductive layer, and another insulating layer. Such composite layer can repeat multiple times to increase the shielding effect. The conductive layer can be grounded.

[0027] In operation, the powder particles 110 are fed into the housing of the section 106. As the powder particles 110 move within the section 106 and touch the walls of the housing (and / or the internal components 114 within the section 106), the charged conductive material of the housing acts as a charging element for transferring charge to the powder particles 110 due to the potential difference between the conductive material at a different potential than the “uncharged” powder particles 110. The powder particles 110 eventually move through the section 106 and are dispensed by the section 106 onto or above the surface of the web 102 to create the powder particle coating on the web 102. After being charged, the powder particles 110 have a greater affinity to be attracted to the web 102, thereby creating a more uniform coating on the web 102. The section 106 therefore acts as both a dispensing / dispersion mechanism and a direct charging mechanism for the system 100. Rather than having separate components that perform this function, the system 100 advantageously provides a means for simultaneously performing the charging and dispensing / dispersing steps in a single unit of the system 100. The advantages of charging the power particles 110 as they are being dispensed, conveyed, and dispersed is related to charge transfer effectiveness, minimizing charge decay in the powder particles 110, and providing a more compact system.

[0028] In some embodiments, greater than 50% (and preferably greater than 80%) of the powder particles 110 make direct surface contact with the charged material of the section 106. In some embodiments, the percentage of powder particles 110 that make direct surface contact with the charged material of the section 106 can be about, e.g., 50-100% inclusive, 50-90% inclusive, 50-80% inclusive, 50-70% inclusive, 50-60% inclusive, 60-90% inclusive, 60-80% inclusive, 60-70% inclusive, 60-100% inclusive, 70-100% inclusive, 80-100% inclusive, 90-100% inclusive, 50%, 60%, 70%, 80%, 90%, 100%, or the like. Although discussed herein as making direct contact with the surface of the charged material, it should be understood that powder particles 110, after charging, can transfer at least a portion of the charge to other powder particles 110 within the section 106 which have not contacted the charged material of the section 106. The higher the percentage of charged particles 110, the more control of the particles 110 exists for guiding the particles 110 to the surface of the web 102. In some embodiments, the desired percentage of contact with the charging element can vary depending on the orientation of the dispersion from the section 106, e.g., directly over the web 102 can necessitate a lower percentage as compared to dispersion in a vertical orientation of the web 102.

[0029] The percentage of direct contact of the powder particles 110 with the charged material of the section 106 can be achieved in various ways. In a system 100 that relies on pressurized fluid (such as air) to dispense and / or disperse the powder particles 110, a high degree of turbulence and intermixing can be used to increase the statistical probability for the powder particles 110 to make contact with the charged material. In some embodiments, a Reynolds number (Re) of greater than 2000 can be used to achieve sufficient turbulent intermixing. In some embodiments, a Reynolds number (Re) of greater than 3000 can be used to achieve sufficient turbulent intermixing. The selection of the Reynolds number (Re) can be dependent on the type of flow and geometry of the system 100. Such pressurized fluid with turbulent intermixing can be used for a section 106 that relies on nozzles and / or distribution pipes for dispensing the powder particles 110.

[0030] In a system 100 that relies on mechanical means for dispensing and / or dispersing of the powder particles 1 10, the powder particles 110 must either be continuously moved (e.g., tumbled, agitated, or the like) to increase the probability of direct contact to greater than 50%. In some embodiments, for systems 100 relying on mechanical means for dispensing and / or dispersing, the powder bulk volume during the mechanical conveying process can be reduced to increase the percentage of surface interaction between the powder particles 1 10 and the direct charging surface. Thus, reducing the volume of the powder particles 110 passing through the section 106 can increase the percentage of surface contact (and / or the repeating contact opportunities). In embodiments using conductive or semi -conductive powders, the powder layer on the web 102 can be larger as the powder particles 110 themselves will conduct charge through the bulk of the powder layer.

[0031] As discussed herein, the section 106 can be in a variety of forms configured to disperse and / or dispense the powder particles 110 after charging. In the embodiment of FIG. 1, the section 106 is in the form of a distribution pipe including multiple openings 120 along the bottom surface. As the powder particles 110 pass through the distribution pipe and contact the charged internal surfaces of the distribution pipe, the powder particles 110 are charged. Turbulent airflow within the distribution pipe increases the opportunities for contact with the charged surfaces and / or increases contact time of the power particles 110 with the charged surfaces of the distribution pipe. The charged powder particles 110 (as well as uncharged powder particles 110) pass through the openings 120 to dispense the powder particles 110 onto the web 110. The charged particles 110 have a greater affinity to the surface of the web 110, and are thereby guided to the surface of the web 102 to create a coating.

[0032] FIG. 2 is a diagrammatic view of an exemplary dual function powder charging and dispersion system 200 (hereinafter “system 200”) including a stripping brush as the dispensing / dispersion mechanism. The system 200 can be substantially similar to the system 100 except for the distinctions provided herein. The system 200 includes a hopper 202 that receives a powder particle 204 mixture. The hopper 202 includes an opening 206 at the bottom for incrementally releasing the powder particles 204 onto a dispersion and / or dispensing section 209, which is in the form of a powder feeding roller, with specific examples being a scattering roller 208. As the powder particles 204 land on the top of the scattering roller 208 and the roller 208 rotates along its longitudinal axis, the powder extraction mechanism 214 extracts the powder from the powder feeding roller and the powder particles 204 drop onto the top surface 210 of the web 212.

[0033] The section 209 can include a powder extraction mechanism 214 (e.g., a stripping brush, or the like) disposed adjacent and offset to the side of the roller 208 to extract the powder particles 204 downward towards the web 212. The powder extraction mechanism 214 is fabricated from a conductive material. A power supply 216 provides a voltage to the powder extraction mechanism 214 via an electrical connection 218 such that the powder extraction mechanism 214 acts as the charging element for the powder particles 204. In some embodiments, the roller 208 can also be fabricated from a conductive material, and the power supply 216 provides a voltage to both the powder extraction mechanism 214 and the roller 208 such that both act as the charging elements for the powder particles 204. As the powder particles 204 pass through the section 209, the powderextraction mechanism 214 and / or the roller 208 charge the powder particles 204 before they are dispensed onto the web 212. The section 209 therefore serves as both the dispensing / dispersion system and the charging system. The chamber surrounding the section 209 (e.g., the roller 208 and the powder extraction mechanism 214) can include an insulating and / or shielding material to protect the surrounding components of the system 200 from the voltage supplied to the section 209.

[0034] In some embodiments, the powder extraction mechanism 214 can make electrical contact with the powder particles 204 which are being “stripped” from the surface of the scattering roller 208. As the powder extraction mechanism 214 removes powder particles 204 from the scattering roller 208, the power supply 216 applies a current which flows into the powder particles 204. In some embodiments, the scattering roller 208 surface can be fabricated from an insulating material to reduce charge leakage. If the scattering roller 208 cannot be fabricated from an insulating material, then all other components making contact with the scattering roller 208 (e.g., mounting shaft to bearings, upper powder hopper 202, or the like) can have an insulated surface making contact with the scattering roller 208. Such insulated surfaces are rated for the expected voltages the scattering roller 208 will receive from the power supply. The same principle applies for the powder extraction mechanism 214 contact with any other potentially conductive surfaces of the system 200. For example, an insulating layer exists between the conductive surfaces of the powder extraction mechanism 214 which are performing the powder charging work and any other components surrounding the powder extraction mechanism 214.

[0035] FIG. 3 is a diagrammatic view of an exemplary dual function powder charging and dispersion system 300 (hereinafter “system 300”) including a scattering roller 208 as the dispensing / dispersion mechanism. The system 300 can be substantially similar to the systems 100, 200 except for the distinctions provided herein. Therefore, like reference numbers refer to like structures. In particular, rather than having the powder extraction mechanism 214 as the charging element (as in system 200), the system 300 includes a scattering roller 208 which acts as the charging element of the dispersion and / or dispensing section 302.

[0036] As such, rather than providing voltage to the powder extraction mechanism 214, the power supply 216 provides a current to the scattering roller 208. The electrical connection 218 is therefore made between the power supply 216 and the scattering roller208. As the powder particles 204 pass over the surface of the scattering roller 208, the powder particles 204 receive a charge from the potential of the roller 208 before being dispensed onto the surface 210 of the web 212. In some embodiments, both the scattering roller 208 and the powder extraction mechanism 214 can act as the charging elements of the system 300. The scattering roller 208 can be fabricated from a conductive material to receive the current from the power supply 216. The same insulation and / or isolation considerations discussed with respect to system 200 can be applied to system 300 to provide the necessary protection to surrounding components of the system 300.

[0037] FIG. 4 is a diagrammatic view of an exemplary dual function powder charging and dispersion system 400 (hereinafter “system 400”) including a spray nozzle 402 as the dispensing / dispersion mechanism. The system 400 can be substantially similar to the systems 100, 200, 300 except for the distinctions provided herein. Therefore, like reference numbers refer to like structures. The system 400 includes a chamber 404 receiving and storing the powder particles 406. The spray nozzle 402 is disposed adjacent to the chamber 404 to receive the powder particles 406 for spraying onto the top surface 210 of the web 212.

[0038] The dispersion and / or dispensing section 408 in the form of the spray nozzle 402 serves as both the dispersion / dispensing and charging area of the system 400. In particular, the power supply 216 is connected to the spray nozzle 402 via the electrical connection 218. The spray nozzle 402 is fabricated from a conductive material to bring the nozzle 402 to potential when current is applied from the power supply 216. As the powder particles 406 are sprayed through the nozzle 402, electrons flow into the neutral powder particles 406 during contact of the particles 406 with surfaces of the nozzle 402 to achieve electrodynamic equilibrium.

[0039] The charged powder particles 406 subsequently exist the nozzle 402 and are sprayed onto the top surface 210 of the web 212 for coating. One or more layers of isolation and / or insulation layer 410 are positioned between the chamber 404 and the spray nozzle 402 to protect the surrounding components of the system 400 from the current supplied to the spray nozzle 402. In some embodiments, the entire spray nozzle 402 can be surrounding by the isolation and / or insulation layer 410 (except for the entrance and exit of the spray nozzle 402). The section 408 of the system 400 therefore acts as both a dispensing / dispersing mechanism and a direct charging mechanism for the powder particles 406.

[0040] While exemplary embodiments have been described herein, it is expressly noted that these embodiments should not be construed as limiting, but rather that additions and modifications to what is expressly described herein also are included within the scope of the invention. Moreover, it is to be understood that the features of the various embodiments described herein are not mutually exclusive and can exist in various combinations and permutations, even if such combinations or permutations are not made express herein, without departing from the spirit and scope of the invention.

Claims

CLAIMS:

1. A dual function powder charging and dispersion system for powder coating, the system comprising: a powder particle chamber configured to receive powder particles; a dispersion section configured to receive the powder particles from the powder particle chamber; and a power supply electrically connected to the dispersion section to supply a current to at least one structure within the dispersion section such that the at least one structure serves as a charging element for charging of the powder particles within the dispersion section; wherein the dispersion section acts as a means for both (i) charging the powder particles within the dispersion section with the charging element and (ii) dispersing or dispensing charged powder particles from the dispersion section onto a substrate.

2. The dual function powder charging and dispersion system of claim 1, wherein the powder particle chamber is a hopper with an opening adjacent to the dispersion section, the opening configured to incrementally release the powder particles into the dispersion section.

3. The dual function powder charging and dispersion system of claim 1, comprising an insulation and / or isolation layer between the dispersion section and the powder particle chamber.

4. The dual function powder charging and dispersion system of claim 1, comprising an insulation and / or isolation layer between the at least one structure of the dispersion section and the powder particle chamber.

5. The dual function powder charging and dispersion system of claim 1, wherein contact of the powder particles with the at least one structure within the dispersion section during passage of the powder particles through the dispersion section charges at least a portion of the powder particles prior to dispersing or dispensing of the powder particles from the dispersion section.

6. The dual function powder charging and dispersion system of claim 1 , wherein theat least one structure is fabricated from a conductive material.

7. The dual function powder charging and dispersion system of claim 1, wherein the at least one structure of the dispersion section is a spray nozzle.

8. The dual function powder charging and dispersion system of claim 1, wherein the at least one structure of the dispersion section is a distribution pipe with multiple openings formed therein for dispersing or dispensing of the charged powder particles from the distribution pipe.

9. The dual function powder charging and dispersion system of claim 1 , wherein the at least one structure of the dispersion section is a powder extraction mechanism, and the dispersion section further includes a powder feeding roller positioned adjacent to the stripping brush.

10. The dual function powder charging and dispersion system of claim 1, wherein the at least one structure of the dispersion section is a scattering roller, and the dispersion section further includes a stripping brush positioned adjacent to the scattering roller.

11. The dual function powder charging and dispersion system of claim 1 , wherein the at least one structure of the dispersion section is both a scattering roller and a stripping brush positioned adjacent to the scattering roller.

12. A system for powder coating, the system comprising: a substrate configured to move from a proximal end to a distal end of a containment enclosure; and a dual function powder charging and dispersion system disposed adjacent to the substrate, the dual function powder charging and dispersion system including: a powder particle chamber configured to receive powder particles; a dispersion section configured to receive the powder particles from the powder particle chamber; and a power supply electrically connected to the dispersion section to supply a current to at least one structure within the dispersion section such that the at least one structure serves as a charging element for charging of the powder particles within the dispersion section;wherein the dispersion section acts as a means for both (i) charging the powder particles within the dispersion section with the charging element and (ii) dispersing or dispensing charged powder particles from the dispersion section onto the substrate.

13. The system of claim 12, wherein the at least one structure is fabricated from a conductive material.

14. The system of claim 12, wherein the at least one structure of the dispersion section is at least one of a spray nozzle, a distribution pipe with multiple openings formed therein, a stripping brush positioned adjacent to a scattering roller, or a scattering roller positioned adjacent to the stripping brush.

15. A method of powder coating, comprising: passing powder particles from a powder particle chamber to a dispersion section of a dual function powder charging and dispersion system; supplying a current to at least one structure within the dispersion section with a power supply electrically connected to the dispersion section such that the at least one structure serves as a charging element; and charging at least a portion of the powder particles within the dispersion section with the charging element; wherein the dispersion section acts as a means for both (i) charging the powder particles within the dispersion section with the charging element and (ii) dispersing or dispensing charged powder particles from the dispersion section onto a substrate.

16. The method of claim 15, wherein an insulation and / or isolation layer is disposed between the dispersion section and the powder particle chamber.

17. The method of claim 15, wherein an insulation and / or isolation layer is disposed between the at least one structure of the dispersion section and the powder particle chamber.

18. The method of claim 15, wherein contact of the powder particles with the at least one structure within the dispersion section during passage of the powder particles through the dispersion section charges at least a portion of the powder particlesprior to dispersing or dispensing of the powder particles from the dispersion section.

19. The method of claim 15, wherein the at least one structure is fabricated from a conductive material.

20. The method of claim 15, wherein the at least one structure of the dispersion section is at least one of a spray nozzle, a distribution pipe with multiple openings formed therein, a stripping brush positioned adjacent to a scattering roller, or a scattering roller positioned adjacent to the stripping brush.

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