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Re: Powder Coating



Joanne:

You bring up some good questions. Actually there are many good uses
for the waste depending on the type of powder being applied. Powder
coatings can be formulated in a variety of chemistries dpending on the
characteristics required of the final product shell.  In addition to
resistance to UV rays and chemicals, the gloss, hardness and
durabil;ity are just a few of the characteristics demanded of the
final product. Because of the above it is extremely difficult to
determine the characteristics of the waste stream and what it could be
mixed with by a secondary user.

The powders may be epoxies, acrylics, polyesters, and polyurethanes,
with even the nylons, polypropelylenes and teflons also being used in
specialized formulations.  Since many of the resins don't tend to
cohabitate, all powders must be sorted by color, chemistry, and
supplier to  be sure of a set of common characteristics for a blend.  

The powders are carried within the coating system in a "fluidized"
state(floating in air) in order to get them to the "gun".  Most powder
systems make use of the High Voltage(100,000) volt Electrostaic
charges to direct the particles to the workpiece. Since the larger
particular pick up "more " charge, the "overspray" (recirculated
powder) gradually becomes a mix of fine and superfine pieces that may
lack some characteristics of the original batch of virgin material.

Not to appear entirely negative to the reuse of offal from any 
process, The reuse of powders within the process or an alternate
"fluidized Bed" coating process(heavy coatings like a dishwasher
frame) might be a better use than to guess at the tensile and
compression values of a remote use like a brick.


Vic Young

========================================

Date:          Wed, 02 Jul 1997 10:23:39 -0500 (EST)
From:          "Jo Anne Hollash (717) 787-7382"
<HOLLASH.JOANNE@a1.pader.gov> Subject:       Powder Coating To:       
    p2tech@great-lakes.net Reply-to:      p2tech@great-lakes.net

   I read this exchange with interest.  I am curious if the "waste"
   mixed coating powder can be blended into some form of plastic? 
   Would there be any way to supply a plastic products manufacturer to
   use the "waste" as a product where color is not critical?  For
   example, would it blend into automotive bumper plastic which, I
   think, is coated to match the automobile?

   Or

   If this bakes into a brick, could the material blended into plastic
   and baked into strips and marketed as garden edging, etc?  Could
   the speckles of color be marketed as a benefit - such as "one of a
   kind" consumer items?  Would the finished product be non-toxic? 
   Could the baked product be fashioned into flower pots, children's
   toys, etc ?

               Jo Anne
Vic Young, Waste Reduction Resource Center
PO Box 29569, Raleiigh, NC 27626-9569
(800)476-8686 Fax (919)715-6794
vic_young@owr.ehnr.state.nc.us
http://www.owr.ehnr.state.nc.us/wrrc1.htm