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US 5,688,563 AGranted
Electrostatic system for controlling the flow of a fluid after being coated onto a substrate
AssigneeMinnesota Mining and Manufacturing Company
InventorsJohn W. Louks, Steven H. Gotz
Life of this patent
Estimating the term…
Abstract
A system controls the flow of a conductive fluid after the fluid is coated onto a substrate by applying an electrostatic force to the coated fluid. The force applied to the fluid can be controlled to counteract the fluid tendency to dewet to a thicker state if significant interfacial surface tension differences exists between the fluid and substrate.
Claims25
A method for minimizing the flow of a fluid after the fluid is coated by a coater onto a first side of a substrate and until further control of the fluid flow is not needed, the method comprising the steps of:
- positioning an electrostatic field generator having at least one element relative to the fluid on the substrate for imposing at least one electrostatic field on the fluid to oppose the dewetting tendency of the fluid and to minimize the flow of the fluid after the fluid is coated onto the substrate, the at least one electrostatic field having a field strength;
- and
- subjecting each given point in a desired region on the substrate to a pulsing electrostatic field to vary over time the field strength between a higher and a lower level at least once, thereby to prevent the fluid from becoming electrostatically unaffected by the at least one electrostatic field and to enable the at least one electrostatic field to continue to oppose the dewetting tendency of the fluid.
A method for minimizing the flow of a fluid after the fluid is coated by a coater onto a first side of a substrate and until further control of the fluid flow is not needed, the substrate having a second side opposite the first side of the substrate, wherein the method comprises the steps of:
- positioning an electrostatic field generator relative to the fluid on the substrate for imposing at least one electrostatic field on the fluid to pull the fluid against the first side of the substrate and to minimize the flow of the fluid after the fluid is coated onto the substrate, the at least one electrostatic field having a field strength, wherein the electrostatic generator comprises at least a first element and a second element positioned adjacent the second side of the substrate, the first element being charged to a first voltage to create a first electrostatic field having a first field strength and the second element being charged to a second voltage to create a second electrostatic field having a second field strength, the first and second field strengths being different, the first element being spaced from the second element such that the fluid is exposed to the first electrostatic field followed by the second electrostatic field, the electrostatic generator further comprising a third element and a fourth element positioned adjacent the second side of the substrate, the third element being charged to approximately the first voltage to create a third electrostatic field having approximately the first field strength, the fourth element being charged to approximately the second voltage to create a fourth electrostatic field having approximately the second field strength, the third and fourth elements being spaced from and positioned relative to the first and second elements such that the fluid is consecutively exposed to the first, second, third, and fourth electrostatic fields and such that the fluid is pulsed by electrostatic fields of differing field strengths;
- and
- varying the field strength sufficiently to prevent the fluid from becoming electrostatically unaffected by the electrostatic fields and to enable the at least one electrostatic field to continue to pull the fluid against the first side of the substrate.
A method for minimizing the flow of a fluid after the fluid is coated by a coater onto a first side of a moving substrate and until the apparatus is not needed to control the flow, the moving substrate having a second side opposite the first side, the method comprising the steps of:
- positioning a first element relative to the coater and adjacent the second side of the substrate, the first element being charged to a first voltage such that the first element imposes a first electrostatic field on the fluid pulling the fluid against the first side of the substrate, the first electrostatic field having a first field strength;
- positioning a second element relative to the coater and adjacent the second side of the substrate, the second element being charged to a second voltage such that the second element imposes a second electrostatic field on the fluid pulling the fluid against the first side of the substrate, the second electrostatic field having a second field strength, the second field strength being different from the first field strength, the second element being spaced from the first element such that the fluid is exposed to the first electrostatic field before being exposed to the second electrostatic field when transported from the coater;
- positioning a third element relative to the coater and adjacent the substrate second side, the third element being charged to a third voltage such that the third element imposes a third electrostatic field on the fluid pulling the fluid against the first side of the substrate, the third electrostatic field having a third field strength, the third field strength being different from the second field strength, the third element being spaced from the first and second elements such that the fluid is exposed to the first electrostatic field before being exposed to the second electrostatic field and such that the fluid is exposed to the second electrostatic field before being exposed to the third electrostatic field when the substrate is transported from the coater;
- and
- transporting the moving substrate adjacent the first, second, and third elements at a transport rate after the fluid is coated onto the moving substrate, the transport rate being sufficient to prevent the fluid from becoming electrostatically unaffected by the first, second, and third electrostatic fields and such that the flow of the fluid is minimized by the first, second, and third electrostatic fields.
2 more elements
A method for applying a fluid coating onto a first side of a substrate and for controlling the flow of the fluid coating until the fluid coating loses its tendency to flow, the method comprising the steps of:
- applying the fluid coating to the first side of the substrate;
- imposing at least one electrostatic field on the fluid coating to oppose the dewetting tendency of the fluid and to minimize the flow of the fluid coating after the fluid coating is applied to the substrate;
- subjecting each given point in a desired region on the substrate to a pulsing electrostatic field to vary over time the field strength between a higher and a lower level at least once, while imposing the at least one electrostatic field upon the fluid coating, thereby to prevent the fluid from becoming electrostatically unaffected by the at least one electrostatic field and to enable the at least one electrostatic field to continue to oppose the dewetting tendency of the fluid;
- and
- solidifying the fluid coating to reduce the fluid tendency to flow while the step of imposing the at least one electrostatic field is taken.
2 more elements
An apparatus for controlling the flow of a fluid after the fluid is coated by a coater onto a first side of a substrate and until the apparatus is not needed to control the flow, the apparatus comprising:
- an electrostatic field generator positioned relative to the fluid on the substrate for imposing at least one electrostatic field on the fluid to oppose the dewetting tendency of the fluid and to control the flow of the fluid after the fluid is coated onto the substrate, the at least one electrostatic field having a field strength;
- and
- means for subjecting each given point on the substrate to a pulsing electrostatic field to vary over time the field strength between a higher and a lower level at least once, thereby to prevent the fluid from becoming electrostatically uncontrollable by the at least one electrostatic field and to enable the at least one electrostatic field to continue to oppose the dewetting tendency of the fluid.
An apparatus for controlling the flow of a fluid after the fluid is coated by a coater onto a first side of a substrate and until the apparatus is not needed to control the flow, the substrate having a second side opposite the first side, wherein the apparatus comprises:
- an electrostatic field generator positioned relative to the fluid on the substrate for imposing at least one electrostatic field on the fluid to pull the fluid against the first side of the substrate and to control the flow of the fluid after the fluid is coated onto the substrate, the at least one electrostatic field having a field strength, the electrostatic generator comprising at least a first element and a second element positioned adjacent the second side of the substrate, the first element being charged to a first voltage to create a first electrostatic field having a first field strength and the second element being charged to a second voltage to create a second electrostatic field having a second field strength, the first and second field strengths being different, the first element being spaced from the second element such that the fluid is exposed to the first electrostatic field followed by the second electrostatic field, the electrostatic generator further comprising a third element and a fourth element positioned adjacent the second side of the substrate, the third element being charged to approximately the first voltage to create a third electrostatic field having approximately the first field strength, the fourth element being charged to approximately the second voltage to create a fourth electrostatic field having approximately the second field strength, the third and fourth elements being spaced from and positioned relative to the first and second elements such that the fluid is consecutively exposed to the first, second, third, and fourth electrostatic fields and such that the fluid is pulsed by electrostatic fields;
- and
- means for varying the field strength sufficiently to prevent the fluid from becoming electrostatically uncontrollable by the at least one electrostatic field and to enable the at least one electrostatic field to continue to pull the fluid against the first side of the substrate.
An apparatus for controlling the flow of a fluid after the fluid is coated by a coater onto a first side of a moving substrate and until the fluid is sufficiently set up and the apparatus is not needed to control the flow, the moving substrate having a substrate second side opposite the substrate first side, the apparatus comprising:
- a first element positioned relative to the coater and adjacent the substrate second side, the first element being charged to a first voltage such that the first element imposes a first electrostatic field on the fluid pulling the fluid against the substrate first side, the first electrostatic field having a first field strength;
- and
- a second element positioned relative to the coater and adjacent the second side, the second element being charged to a second voltage such that the second element imposes a second electrostatic field on the fluid pulling the fluid against the substrate first side, the second electrostatic field having a second field strength, the second electrostatic field strength being different from the first electrostatic field strength, the second element being spaced from the first element such that the fluid is exposed to the first electrostatic field before being exposed to the second electrostatic field.
Dependencies are inferred from the claim text.