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Unipolarity powder coating systems including improved tribocharging and corona guns

A technology of friction electrification and electrification polarity, which is applied in the direction of friction discharge spraying, electrostatic spraying device, spraying device, etc., and can solve problems such as internal corner spraying of parts that cannot be sprayed, damage to powder conveying parts, etc.

Inactive Publication Date: 2005-07-06
NORDSON CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

A major disadvantage of corona guns is that they do not coat the inside corners of parts well due to the strong electrostatic field or Faraday Cage effect generated by the corona electrodes
The second disadvantage of corona guns is: due to the formation of free ions, back ionization (back ionization) can occur on the surface of the sprayed part to form pinholes or orange peel surfaces
Another disadvantage of this type of gun is that system components such as nozzles, diffusers, and powder delivery system components such as pumps, hoppers, and other parts that come into contact with the powder delivery system are usually made of polyethylene or polytetrafluoroethylene. (PTFE) made of such materials
Additionally, this positive triboelectric charging can damage powder delivery components such as the hose that connects the pump body to the spray gun

Method used

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  • Unipolarity powder coating systems including improved tribocharging and corona guns
  • Unipolarity powder coating systems including improved tribocharging and corona guns
  • Unipolarity powder coating systems including improved tribocharging and corona guns

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0052] A mixture of 20% polytetrafluoroethylene and 80% nylon 6 / 6, a polyamide / halogenated hydrocarbon resin mixture, was prepared as a disc. For comparison, conventional materials such as nylon and Teflon (Teflon) samples were also prepared at the same time.

[0053] Relative conversion efficiencies were determined for powder coatings applied by a fan-shaped fog cone spray nozzle with an opening of 0.450 inches by 0.065 inches, which sprayed the paint on the pan at a 45-degree angle at an air flow rate of 4 cubic feet per minute superior. Powder impinging on the surface of the disc of tribo-charged material is deflected from the disc onto a grounded metal target. The raw charge measured for the powder present in the nozzle was zero. Therefore, all these powders are charged by impacting the friction material. The ratio of the powder sticking to the metal target to the total powder is defined as the relative conversion efficiency. Typically 50 grams of epoxy polyester powde...

example 2

[0056] Prepare several plates of 5% PTFE and 95% nylon 6 / 6, polyamide mixture, and conduct conversion efficiency experiments as in Example 1. The results are shown in Table I.

[0057] The advantage of using polyamide mixtures in powder spray guns is that the charging of the powder is increased due to the increased discharge on the surface of the triboelectric gun. The increase in surface discharge is due to the incompatibility of the polymers, which creates leakage paths that would not occur in homogeneous polymers. Another advantage of using these polyamide blends is that the hygroscopicity of the nylon is reduced when the nylon is filled with PTFE or polyethylene.

[0058] 2. Polyamide resin reinforced fiber

[0059] Polyamide resin reinforcement fibers include polyamide polymers filled with polyamide fibers. The weight percentage of the polyamide polymer is preferably about 50% to 99%, more preferably about 85% to 95%. Wherein the weight percentage of the polyamide fib...

example 3

[0064] Several disks of polyamide resin reinforced fibers were prepared. For comparison, conventional fiber-free nylon and Teflon samples were also prepared at the same time. The conversion efficiency experiment was carried out as in Example 1. The results are shown in Table I.

[0065] example

Material

Plate thickness (inch)

polarity

Relative Conversion Efficiency%

Compared

Nylon 6,6

0.155

-

16.5

1

Nylon 6, 5% in 6

PTFE

0.250

-

21.3

2

Nylon 6, 20% in 6

PTFE

0.250

-

24.7

3

Nylon 6, 10% in 6

KEVLAR®

0.123

-

39.2

Compared

100% KEVLAR® fiber

-

+

54.3

4

Fill R MoS 2 Nylon

0.118

-

22.4

[0066] Surprisingly, the nylon added to the fiber negatively charged the powder except for the KEVLAR(R) fiber in the comparative example, which charged the powder ...

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Abstract

The present invention describes a variety of unconventional tribo-negative materials for use as powder contact surfaces in tribo- and corona powder spray guns, in-gun components, and powder delivery system components. The present invention also provides a short barrel triboelectric powder spray gun having interchangeable powder contact inserts and nozzles. The present invention further provides a new type of friction electrification and corona gun structure. The improved powder coating system allows the use of a triboelectric negative gun with a negative corona gun to coat different parts of the same part in the powder coating system. The present invention also provides an inside-out structure in which pressurized air directs the powder coating to the charged surface. In other configurations of the present invention, the air nozzle-induced triboelectric charging and conventional triboelectric charging parts are also combined in a single gun.

Description

[0001] related application [0002] This application is a continuation-in-part of U.S. Patent Application Serial No. 09 / 724,363, filed November 28, 2000, for UNIPOLARITY POWDER COATING SYSTEMSINCLUDING IMPROVED TRIBOCHARGING AND CORONA GUNS, which is hereby incorporated by reference in its entirety this application. This application also claims priority to U.S. Patent Application UNIPOLARITY POWDER COATING SYSTEMSINCLUDING AN IMPROVED TRIBOCHARGING GUN, UNIPOLARITY GUN METHOD FOR MAKING SAME, filed July 11, 2000, with application serial number 60 / 217,216, the full text of which is hereby filed at This application is incorporated by reference. technical field [0003] This invention relates to powder coating systems which use corona and tribocharging powder coating guns to impart an electrostatic charge to the powder to deposit the powder onto a substrate. Background technique [0004] There are two basic types of powder coating guns commonly used when electrostatically pow...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B05B5/025B05B1/02B05B1/04B05B1/26B05B5/03B05B5/04B05B5/047B05B5/053B05B7/08
CPCB05B1/02B05B1/04B05B1/042B05B1/265B05B5/032B05B5/04B05B5/0407B05B5/0418B05B5/0426B05B5/047B05B5/053
Inventor M·R·萨内W·R·雷曼H·J·拉德J·W·梅瑟利G·W·克拉姆A·J·克诺贝S·古斯科夫
Owner NORDSON CORP
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