Electrostatic spray coating system

Claim 2

An electrically insulated high voltage cable of predetermined length measured between opposite ends thereof for conducting electrostatic voltages in excess of approximately 50 KV to a coating-charging electrode in an electrostatic spray coating system, comprising: a plurality of substantially equal length continuous silicon carbide fibers electrically connected primarily in parallel, said fibers each having a length in the approximate range of 1 m-50 m and extending between opposite ends of the cable to provide electrical current flow paths primarily substantially longitudinally along the length of said cable, said plurality of parallel-connected fibers collectively having a diameter measured generally transversely to the length of the cable in the approximate range of 10 -2 cm.-1 cm. and a specific resistivity selected to provide a total resistance measured between the opposite ends of the cable in the approximate range of 1M-1000M ohms, and an insulative sheath surrounding said parallel-connected fibers having a wall thickness and dielectric strength to avoid dialectric breakdown when said cable is connected to an electrostatic voltage supply in excess of approximately 50 KV.

Claim 3

The cable of claim 1 wherein said fibers each have an average diameter in the approximate range of 0.1 micron-100 microns.

Claim 4

The cable of claim 1 wherein said fibers each have an average diameter in the approximate range of 1 micron-25 microns.

Claim 5

The cable of claim 1 wherein said fibers each have an average diameter of approximately 10 microns.

Claim 6

The cable of claim 1 wherein the specific resistivity of said fibers is in the approximate range of 10 2 ohm-cm-10 4 ohm-cm.

Claim 7

The cable of claim 1 wherein the specific resistivity of said fibers is in the approximate range of 2×10 2 ohm-cm.-15×10 2 ohm-cm.

Claim 8

The cable of claim 1 wherein the specific resistivity of said fibers is approximately 10 3 ohm-cm.

Claim 9

The cable of claim 1 wherein said parallel-connected fibers collectively have a total cross-sectional area in the approximate range of 10 -5 cm. 2- 10 -1 cm. 2 .

Claim 10

The cable of claim 1 wherein the fiber length is in the approximate range of 2 m-32 m.

Claim 11

The cable of claim 1 wherein the fiber length is in the approximate range of 4 m-16 m.

Claim 12

The cable of claim 1 wherein said parallel-connected fibers collectively have a cross-sectional area of approximately 3×10 -3 cm. 2 .

Claim 13

The cable of claim 1 wherein said parallel-connected fibers collectively have a cross-sectional area in the approximate range of 1×10 -3 cm. 2 -6×10 -3 cm. 2 .

Claim 14

The cable of claim 1 wherein said parallel-connected fibers collectively have a cross-sectional area in the approximate range of 10 -4 cm. 2 -10 -2 cm. 2 .

Claim 15

The cable of claim 1 wherein the number of fibers is approximately 2000.

Claim 16

The cable of claim 1 wherein the number of fibers is in the approximate range of 10 2 -10 5 .

Claim 17

The cable of claim 1 wherein the number of fibers is in the approximate range of 10 3 -10 4 .

Claim 18

An electrically insulated high voltage cable of predetermined length measured between opposite ends thereof for conducting electrostatic voltages in excess of approximately 50 KV to a coating-charging electrode in an electrostatic spray coating system, comprising: a plurality of substantially equal length continuous silicon carbide fibers electrically connected primarily in parallel, said fibers extending between opposite ends of the cable to provide electrical current flow paths primarily substantially longitudinally along the length of said cable, said plurality of parallel-connected fibers collectively having a total diameter measured generally transversely to the length of the cable and a resistivity selected to provide a total resistance measured between the opposite ends of the cable in the approximate range of 1M ohms-100M ohms per lineal meter of cable, and an insulative sheath surrounding said parallel-connected fibers having a wall thickness and dielectric strength to avoid dialectric breakdown when said cable is connected to an electrostatic voltage supply in excess of approximately 50 KV.

Claim 19

An electrically insulated high voltage cable of predetermined length measured between opposite ends thereof for conducting electrostatic voltages in excess of approximately 50 KV to a coating-charging electrode in an electrostatic spray coating system, comprising: a plurality of substantially equal length continuous silicon carbide fibers electrically connected primarily in parallel, said fibers extending between opposite ends of the cable to provide electrical current flow paths primarily substantially longitudinally along the length of said cable, said plurality of parallel-connected fibers collectively having a total diameter measured generally transversely to the length of the cable and a resistivity selected to provide a total resistance measured between the opposite ends of the cable in the approximate range of 1M ohms-100M ohms per lineal meter of cable, and an insulative sheath surrounding said parallel-connected fibers having a wall thickness and dielectric strength to avoid dialectric breakdown when said cable is connected to an electrostatic voltage supply in excess of approximately 50 KV.

Claim 20

The high voltage cable of claim 17 wherein said total resistance is in the approximate range of 5M ohms-65M ohms per lineal meter of cable.

Claim 21

The high voltage cable of claim 17 wherein said total resistance is in the approximate range of 10M ohms-40M ohms per lineal meter of cable.

Claim 22

An electrostatic spray coating system comprising: a high voltages electrostatic supply for providing electrostatic voltages in excess of 50 KV, a spray device for emitting coating particles toward an article to be coated, an electrode mounted to the spray device in charging relationship to coating particles emitted by the spray device, an electrical path interconnecting the high voltage supply and the electrode composed of a plurality of continuous silicon carbide fibers electrically connected primarily in parallel and disposed along said electrical path to provide electrical current flow paths primarily substantially longitudinally between said electrode and high voltage supply each said fiber having a length in the approximate range of 1 m-50 m, said fibers collectively having a total diameter measured generally transversely to said path in the approximate range of 10 -2 cm.-1 cm. and a specific resistivity selected to provide a total resistance between said electrode and high voltage supply in the approximate range of 1M-1000M ohms.

Claim 23

An electrostatic spray coating system comprising: a high voltages electrostatic supply for providing electrostatic voltages in excess of 50 KV, a spray device for emitting coating particles toward an article to be coated, an electrode mounted to the spray device in charging relationship to coating particles emitted by the spray device, an electrical path interconnecting the high voltage supply and the electrode composed of a plurality of continuous silicon carbide fibers electrically connected primarily in parallel and disposed along said electrical path to provide electrical current flow paths primarily substantially longitudinally between said electrode and high voltage supply each said fiber having a length in the approximate range of 1 m-50 m, said fibers collectively having a total diameter measured generally transversely to said path in the approximate range of 10 -2 cm.-1 cm. and a specific resistivity selected to provide a total resistance between said electrode and high voltage supply in the approximate range of 1M-1000M ohms.

Claim 24

An electrostatic spray coating system comprising: a spray device for emitting coating particles toward an article to be coated, an electrode mounted to the spray device in charging relationship to coating particles emitted by the spray device, a high voltage electrostatic supply located remote from said spray device for providing electrostatic voltages in excess of 50 KV, a first high voltage path terminating at opposite ends interconnected between the remote high voltage supply and the spray device, said first path composed of a plurality of continuous silicon carbide fibers electrically connected primarily in parallel and extending between said opposite ends of said path to provide electrical current flow paths primarily substantially longitudinally along said first path, each said fiber having a length measured between said opposite first path ends in the approximate range of 1 m-50 m, said fibers collectively having a total diameter measured generally transversely to said first path in the approximate range of 10 -2 cm.-1 cm. and a specific resistivity selected to provide a total resistance measured between the opposite ends of said first path in the approximate range of 1M-(1000-N)M ohms, where N is a number less than 1000, and a second high voltage path in the spray device interconnected between said first path and the electrode, said second path composed a plurality of continuous silicon carbide fibers electrically connected primarily in parallel, disposed between said first path and said electrode to provide electrical current flow paths primarily substantially longitudinally therebetween, and collectively having a total diameter measured generally transversely to said second path in the approximate range of 10 -2 cm.-1 cm. and a length and specific resistivity selected to provide a total resistance between said first path and said electrode in the approximate range of NM ohms.

Claim 25

An electrostatic spray coating system comprising: a spray device for emitting coating particles toward an article to be coated, an electrode mounted to the spray device in charging relationship to coating particles emitted by the spray device, a high voltage electrostatic supply located remote from said spray device for providing electrostatic voltages in excess of 50 KV, a first high voltage path terminating at opposite ends interconnected between the remote high voltage supply and the spray device, said first path composed of a plurality of continuous silicon carbide fibers electrically connected primarily in parallel and extending between said opposite ends of said path to provide electrical current flow paths primarily substantially longitudinally along said first path, each said fiber having a length measured between said opposite first path ends in the approximate range of 1 m-50 m, said fibers collectively having a total diameter measured generally transversely to said first path in the approximate range of 10 -2 cm.-1 cm. and a specific resistivity selected to provide a total resistance measured between the opposite ends of said first path in the approximate range of 1M-(1000-N)M ohms, where N is a number less than 1000, and a second high voltage path in the spray device interconnected between said first path and the electrode, said second path composed a plurality of continuous silicon carbide fibers electrically connected primarily in parallel, disposed between said first path and said electrode to provide electrical current flow paths primarily substantially longitudinally therebetween, and collectively having a total diameter measured generally transversely to said second path in the approximate range of 10 -2 cm.-1 cm. and a length and specific resistivity selected to provide a total resistance between said first path and said electrode in the approximate range of NM ohms.

Claim 26

An electrostatic spray coating system comprising: a spray device for emitting coating particles toward an article to be coated, an electrode mounted to the spray device in charging relationship to coating particles emitted by the spray device, a high voltage electrostatic supply mounted to said spray device for providing electrostatic voltages in excess of 50 KV at a location spaced from the electrode, and an electrical path terminating at opposite ends interconnecting the high voltage supply and the electrode composed of a plurality of continuous silicon carbide fibers electrically connected primarily in parallel and disposed between said opposite ends to provide electrical current flow paths substantially longitudinally along said paths, said fibers having a length measured along said path, a total diameter measured generally transversely to said path, and specific resistivity selected to provide a total resistance between the opposite ends thereof in the approximate range of 1M-1000 ohms.

Claim 27

An electrostatic spray coating system comprising: a spray device for emitting coating particles toward an article to be coated, an electrode mounted to the spray device in charging relationship to coating particles emitted by the spray device, a high voltage electrostatic supply mounted to said spray device for providing electrostatic voltages in excess of 50 KV at a location spaced from the electrode, and an electrical path terminating at opposite ends interconnecting the high voltage supply and the electrode composed of a plurality of continuous silicon carbide fibers electrically connected primarily in parallel and disposed between said opposite ends to provide electrical current flow paths substantially longitudinally along said paths, said fibers having a length measured along said path, a total diameter measured generally transversely to said path, and specific resistivity selected to provide a total resistance between the opposite ends thereof in the approximate range of 1M-1000 ohms.

Claim 28

The electrostatic spray coating system of claim 20 wherein the spray device includes a rotary atomizing member with respect to which said electrode is mounted for charging said coating particles atomized thereby, and wherein the electrode is composed of continuous silicon carbide fibers.

Claim 29

The electrostatic spray coating system of claim 23 wherein the atomizing member has an edge whereat atomization of coating particles occurs and a flow surface over which coating particles flows towards said edge for atomization thereat, and wherein said continuous silicon carbide fiber electrode is ring-shaped and mounted to said atomizing member for rotation therewith in electrostatic charging relationship to said coating.

Claim 30

An electrostatic spray assembly comprising: a spray device for emitting coating particles toward an article to be coated, an electrode mounted to the spray device in charging relationship to coating particles emitted by the spray device, and an electrical path terminating at opposite ends connectable between the electrode and a supply of electrostatic voltage in excess of 50 KV, said path composed of a plurality of continuous silicon carbide fibers electrically connected primarily in parallel and which are disposed between said oppoiste ends to provide electrical current flow paths primarily substntially longitudinally along said path, each said fiber having a length measured along said path in the approximate range of 1 m-50 m, said fibers collectively having a total diameter measured generally transversely to said path in the approximate range of 10 -2 cm.-1 cm. and a specific resistivity selected to provide a total resistance measured between the opposite ends thereof in the approximate range of 1M-1000M ohms.

Claim 31

An electrostatic spray assembly comprising: a spray device for emitting coating particles toward an article to be coated, an electrode mounted to the spray device in charging relationship to coating particles emitted by the spray device, and an electrical path terminating at opposite ends connectable between the electrode and a supply of electrostatic voltage in excess of 50 KV, said path composed of a plurality of continuous silicon carbide fibers electrically connected primarily in parallel and which are disposed between said oppoiste ends to provide electrical current flow paths primarily substntially longitudinally along said path, each said fiber having a length measured along said path in the approximate range of 1 m-50 m, said fibers collectively having a total diameter measured generally transversely to said path in the approximate range of 10 -2 cm.-1 cm. and a specific resistivity selected to provide a total resistance measured between the opposite ends thereof in the approximate range of 1M-1000M ohms.

Claim 32

The electrostatic spray assembly of claim 25 wherein the spray device includes a rotary atomizing member with respect to which said electrode is mounted to charge said coating particles, and wherein said electrode is composed of continuous silicon carbide fibers.

Claim 33

The electrostatic spray assembly of claim 26 wherein the atomizing member has an edge whereat atomization of coating particles occurs and a flow surface over which liquid coating particles flows toward said edge for atomization thereat, and wherein said continuous silicon carbide fiber electrode is ring-shaped and mounted to said atomizing member for rotation therewith in electrostatic charging relationship to said coating.

Claim 34

The system of claim 25 wherein said electrode is fabricated of at least one continuous silicon carbide fiber.

Claim 35

An electrostatic spray assembly comprising: a spray device for emitting coating particles toward an article to be coated, an electrode mounted to the spray device in charging relationship to coating emitted by the spray device, a high voltage electrostatic supply mounted to said spray device for providing electrostatic voltages in excess of 50 KV at a location spaced from the electrode, and an electrical path terminating at opposite ends thereof interconnecting the high voltage supply and the electrode composed of a plurality of substantially equal length continuous silicon carbide fibers electrically connected primarily in parallel, disposed between said opposite ends to provide electrical current flow paths primarily substantially longitudinally along said path, and collectively having a length measured along said path, a diameter measured generally transversely to said path, and a specific resistivity selected to provide a total resistance between the opposite ends thereof in the approximate range of 1M-1000M ohms.

Claim 36

An electrostatic spray assembly comprising: a spray device for emitting coating particles toward an article to be coated, an electrode mounted to the spray device in charging relationship to coating emitted by the spray device, a high voltage electrostatic supply mounted to said spray device for providing electrostatic voltages in excess of 50 KV at a location spaced from the electrode, and an electrical path terminating at opposite ends thereof interconnecting the high voltage supply and the electrode composed of a plurality of substantially equal length continuous silicon carbide fibers electrically connected primarily in parallel, disposed between said opposite ends to provide electrical current flow paths primarily substantially longitudinally along said path, and collectively having a length measured along said path, a diameter measured generally transversely to said path, and a specific resistivity selected to provide a total resistance between the opposite ends thereof in the approximate range of 1M-1000M ohms.

Claim 49

The cable of claim 1 wherein the continuous silicon carbide fibers are constructed by a process comprising the steps of: (1) preparing a spinning solution from at least one organosilicon high molecular weight compound having a softening point of higher than 50° C., in which silicon and carbon are the main skeleton components, and spinning said spinning solution into fibers, (2) preliminarily heating the spun fibers at a temperature of 350°-800° C. under vacuum to volatilize low molecular weight compounds contained therein, and (3) baking the thus treated fibers at a temperature of 800°-2000° C. under vacuum or at least one nonoxidizing atmosphere selected from the group consisting of an inert gas, CO gas and hydrogen gas, to form said silicon carbide fibers.

Claim 50

The system of claim 20 wherein the continuous silicon carbide fibers are constructed by a process comprising the steps of: (1) preparing a spinning solution from at least one organosilicon high molecular weight compound having a softening point of higher than 50° C., in which silicon and carbon are the main skeleton components, and spinning said spinning solution into fibers, (2) preliminarily heating the spun fibers at a temperature of 350°-800° C. under vacuum to volatilize low molecular weight compounds contained therein, and (3) baking the thus treated fibers at a temperature of 800°-2,000° C. under vacuum or at least one nonoxidizing atmosphere selected from the group consisting of an inert gas, CO gas and hydrogen gas, to form said silicon carbide fibers.

Claim 51

The high voltage cable of claim 1 further including an intermediate sheath located between said silicon carbide fibers and said insulative sheath, said intermediate sheath having a resistivity in the approximate range of 10 7 -10 9 ohm-cm. to provide resistance intermediate said fibers and insulative sheath.

Claim 52

The high voltage cable of claim 39 wherein said intermediate sheath comprises carbon-filled polypropylene.

Claim 53

The spray coating system of claim 20 further including: an insulative sheath surrounding said parallel-connected fibers having a wall thickness and dielectric strength to avoid dialectric breakdown when said cable is connected to an electrostatic voltage supply in excess of approximately 50 KV, and an intermediate sheath located between said silicon carbide fibers and said insulative sheath, said intermediate sheath having a resistivity in the approximate range of 10 7 -10 9 ohm-cm. to provide resistance intermediate said fibers and insulative sheath.

Claim 54

The spray coating system of claim 41 wherein said intermediate sheath comprises carbon-filled polypropylene.

Claim 55

A composite electrically resistive cable assembly having a length disposed between opposite ends thereof, comprising in combination: a fibrous electrically resistive core disposed along the length of said cable to provide electrical current flow paths primarily substantially longitudinally therealong, said core consisting substantially of silicon carbide; and an electrically insulating jacket surrounding and enveloping said silicon carbide core.

Claim 56

A composite electrically resistive cable assembly having a length disposed between opposite ends thereof, comprising in combination: a fibrous electrically resistive core disposed along the length of said cable to provide electrical current flow paths primarily substantially longitudinally therealong, said core consisting substantially of silicon carbide; and an electrically insulating jacket surrounding and enveloping said silicon carbide core.

Claim 57

The composite electrically resistive cable assembly of claim 43 wherein said core is constructed of a plurality of filaments consisting substantially of silicon carbide.

Claim 58

The cable assembly of claim 44 wherein the specific resistivity of said filaments is in the approximate range of 10 2 ohm-cm to 10 4 ohm-cm.

Claim 59

An electrical cable assembly for transmitting electrostatic voltage from an electrostatic power supply to an electrostatic spray coating device, comprising in combination: an elongated continuous flexible resistor consisting substantially of silicon carbide fibers disposed to provide electrical current flow paths primariy substantially longitudinally therealong; an electrically insulating flexible jacket surrounding and enveloping said silicon carbide resistor; and connection means at each end of said flexible resistor for facilitating connection of said flexible resistor between an electrostatic power supply and an electrostatic spray coating device.

Claim 60

An electrical cable assembly for transmitting electrostatic voltage from an electrostatic power supply to an electrostatic spray coating device, comprising in combination: an elongated continuous flexible resistor consisting substantially of silicon carbide fibers disposed to provide electrical current flow paths primariy substantially longitudinally therealong; an electrically insulating flexible jacket surrounding and enveloping said silicon carbide resistor; and connection means at each end of said flexible resistor for facilitating connection of said flexible resistor between an electrostatic power supply and an electrostatic spray coating device.

Claim 61

The cable assembly of claim 46 wherein said silicon carbide fibers have opposite ends connected to said electrical connection means for facilitating the flow of electrical current along the lengths thereof.

Claim 62

For use in an electrostatic spray coating system having a high voltage electrostatic supply, the combination comprising: a resistorized spray coating device for emitting charged coating particles toward an article to be coated; an electrode mounted to said device in charging relationship to coating particles emitted by said spray device; a resistive element consisting substantially of silicon carbide fibers disposed to provide electrical current flow paths primarily substantially longitudinally therealong; and electrical connection means electrically connected to said resistive silicon carbide fiber element to facilitate connecting said resistive silicon carbide fiber element in an electrical circuit between said high voltage power supply and said electrode.

Claim 63

For use in an electrostatic spray coating system having a high voltage electrostatic supply, the combination comprising: a resistorized spray coating device for emitting charged coating particles toward an article to be coated; an electrode mounted to said device in charging relationship to coating particles emitted by said spray device; a resistive element consisting substantially of silicon carbide fibers disposed to provide electrical current flow paths primarily substantially longitudinally therealong; and electrical connection means electrically connected to said resistive silicon carbide fiber element to facilitate connecting said resistive silicon carbide fiber element in an electrical circuit between said high voltage power supply and said electrode.

Claim 64

The combination of claim 48 wherein said silicon carbide fibers have opposite ends connected to said electrical connection means for facilitating the flow of electrical current along the lengths thereof.

Claim 65

The combination of claim 49 wherein said resistive element is elongated and provided with a cross-sectional configuration which permits flexure of the resistive element about an axis perpendicular to the direction of its length.

Claim 66

An electrostatic spray coating system comprising: a high voltage electrostatic supply for providing electrostatic voltages in excess of 50 KV; a spray device for emitting coating particles toward an article to be coated; an electrode mounted to the spray device in charging relationship to coating particles emitted by the spray device; and a resistive electrical path interconnecting the high voltage supply and the electrode consisting substantially of silicon carbide fibers disposed to provide electrical current flow paths primarily substantially longitudinally therealong.

Claim 67

An electrostatic spray coating system comprising: a high voltage electrostatic supply for providing electrostatic voltages in excess of 50 KV; a spray device for emitting coating particles toward an article to be coated; an electrode mounted to the spray device in charging relationship to coating particles emitted by the spray device; and a resistive electrical path interconnecting the high voltage supply and the electrode consisting substantially of silicon carbide fibers disposed to provide electrical current flow paths primarily substantially longitudinally therealong.

Claim 68

The system of claim 51 wherein said silicon carbide fibers are electrically connected primarily in parallel.

Claim 69

An electrostatic spray coating system comprising: a spray device for emitting coating particles toward an article to be coated; an electrode mounted to the spray device in charging relationship to coating particles emitted by the spray device; a high voltage electrostatic supply located remote from said spray device for providing electrostatic voltages in excess of 50 KV; a first high voltage resistive electrical path interconnected between the remote high voltage supply and the spray device, said first path consisting substantially of flexible silicon carbide filaments electrically connected primarily in parallel and disposed to provide electrical current flow paths primarily substantially longitudinally along the length of said first path; and a second high voltage resistive electrical path interconnected between the first path and the electrode, said second path consisting substantially of at least one silicon carbide filament.

Claim 70

An electrostatic spray coating system comprising: a spray device for emitting coating particles toward an article to be coated; an electrode mounted to the spray device in charging relationship to coating particles emitted by the spray device; a high voltage electrostatic supply located remote from said spray device for providing electrostatic voltages in excess of 50 KV; a first high voltage resistive electrical path interconnected between the remote high voltage supply and the spray device, said first path consisting substantially of flexible silicon carbide filaments electrically connected primarily in parallel and disposed to provide electrical current flow paths primarily substantially longitudinally along the length of said first path; and a second high voltage resistive electrical path interconnected between the first path and the electrode, said second path consisting substantially of at least one silicon carbide filament.

Claim 71

The electrostatic spray coating system of claim 53 wherein said filaments of said first and second paths are electrically and structurally continuous therebetween.

Claim 72

The electrostatic spray coating system of claim 54 wherein said second path consists substantially of a plurality of silicon carbide filaments electrically connected primarily in parallel.

Claim 73

An electrostatic spray coating system comprising: a spray device for emitting coating particles toward an article to be coated; an electrode mounted to the spray device in charging relationship to coating particles emitted by the spray device; a high voltage electrostatic supply mounted to said spray device for providing electrostatic voltages in excess of 50 KV at a location spaced from the electrode; and a resistive electrical path interconnecting the high voltage supply and the electrode consisting substantially of silicon carbide filaments disposed to provide electrical current flow paths primarily substantially longitudinally therealong.

Claim 74

An electrostatic spray coating system comprising: a spray device for emitting coating particles toward an article to be coated; an electrode mounted to the spray device in charging relationship to coating particles emitted by the spray device; a high voltage electrostatic supply mounted to said spray device for providing electrostatic voltages in excess of 50 KV at a location spaced from the electrode; and a resistive electrical path interconnecting the high voltage supply and the electrode consisting substantially of silicon carbide filaments disposed to provide electrical current flow paths primarily substantially longitudinally therealong.

Claim 75

The electrostatic spray coating system of claim 56 wherein said path consists substantially of a plurality of silicon carbide filaments electrically connected primarily in parallel.