Process for Power Coating of Objects

Abstract

In a powder coating process, a primer step is implemented prior to electrostatically applying the powder coating, either in advance of preheating the object to be coated or subsequent thereto, depending upon the selection of materials used in the object to be coated, the primer material being diluted fabric softener applied in a fine mist spray or fog to the object.

Claims

1. A process for power coating, having the steps of electrostatically applying a coating to the surface of an object and then curing that coating at an elevated temperature, the improvement including the step of applying a primer to the surface of the object prior to applying the coating.

2. The process according to claim 1 wherein the primer is selected from materials to increase ability of the surface to support an electrostatic charge which attracts the coating to the surface.

3. The process according to claim 1 wherein the primer material includes fluid fabric softener.

4. The process according to claim 3 wherein the primer material includes a volume of water to dilute the fabric softener prior to application of the primer.

5. The process according to claim 4 wherein the fluid fabric softener is Downy® fabric softener and the volume of water is substantially equal to the volume of fabric softener.

6. The process according to claim 3 wherein the primer is applied to the surface of the object by a fine mist spray.

7. The process according to claim 6 wherein the surface is formed from wood material.

8. The process according to claim 7 wherein the wood material is selected from a group of hardwoods, including beech and maple.

9. The process according to claim 8 wherein the power coating process also includes a preheating step to elevate the temperature of the object prior to applying the coating, and the primer is applied to the surface of the object after the preheating step and before applying the coating to the surface.

10. The process according to claim 8 wherein the wood material is hardwood, and the powder coating process includes a preheating step to elevate the temperature of the object prior to applying the coating, and the primer is applied to the surface of the object before the preheating step.

11. The process according to claim 3 wherein the primer is applied to a hydroscopic surface and allowed sufficient time to be absorbed therein prior to applying the coating.

12. The process according to claim 3 wherein the primer reacts chemically with the surface to form part of the permanent bond of the coating with the surface.

Description

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0012] The present invention is an additional process step in conventional or pre-existing powder coating processes wherein a primer material is applied to the surface of the article or object which is to be powder coated. This extra process step is included prior to electrostatically applying the powder to the surface of the object. The primer material is conventional fluid fabric softener, such as Downy® fabric softener. Preferably, this fabric softener is diluted, such as by adding an equal volume of water, prior to application. Application of the primer material to the object is accomplished by passing the surface of the object through or subjecting it to a “fine mist spray” or fog of the primer material, such that primer material covers the entire surface. This “fine mist spray” is defined by the equivalent result of spraying the primer material (the 50% diluted Downey fabric softener) through a SATAjet® 5000 B spray gun using a 1.4 tip at 35 psi air setting. After the primer coating is applied, the powder coating is applied and then cured at elevated temperatures, in a conventional or pre-existing manner.

[0013] It is believed that fabric softener applied in this manner increases the ability of the surface to support an electrostatic charge which attracts the coating to the surface. Accordingly, the present invention anticipates the use of similar fluid primer materials applied to the surface in a similar manner to achieve this result.

[0014] In specific applications, such as very dry wood boards, the primer step of this invention can be used prior to conventional or pre-existing steps for pre-heating the object prior to applying the powder. In other specific applications, such as when the object to be coated is made from with Beech or Maple hardwoods having a moisture content within the normal range for such commercially available woods, the primer step of this invention can be used after the conventional or pre-existing steps for pre-heating the object.

[0015] In certain specific applications it is believed to be advantageous to allow sufficient time between applying the primer and applying the powder for the primer to be absorbed, at least in part, into the surface of the object to be coated, rather than having the primer merely exist on the surface of that object. In specific applications, it is also believed to be advantageous to allow the primer to react chemically with the surface of the object so as to form part of the permanent bond of the coating with that surface.

[0016] Although the present invention has been shown and described herein with respect to certain preferred embodiments and alternative configurations, those were by way of illustration and example only. For example, while wood, and hardwood in particular, has been used as an example for the material forming the object to be coating, the present invention is also believed to be useful where other materials, having a hydroscopic surface, are used to form that object. Accordingly, the spirit and scope of the present invention is intended to be limited only by the terms of the appended claims.