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Electrostatic Powder Coating of Nonconductors

IP.com Disclosure Number: IPCOM000101843D
Original Publication Date: 1990-Sep-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 58K

Publishing Venue

IBM

Related People

Buchanan, NE: AUTHOR [+3]

Abstract

Disclosed is a process for electrostatic powder coating of nonconductive materials. Previously this process could only be used to coat grounded, conductive materials.

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Electrostatic Powder Coating of Nonconductors

       Disclosed is a process for electrostatic powder coating
of nonconductive materials.  Previously this process could only be
used to coat grounded, conductive materials.

      With a standard EPC (electrostatic powder coating) process a
spray of dry powder is electrically charged and directed toward the
material to be coated.  The charged particles are attracted to the
ground potential of the target and adhere to it.  The coated object
is then heated, reflowing and curing the powder particles, resulting
in a thin solid coating.  Since nonconductors cannot be grounded,
providing a source of attraction for the charged powder, they could
not be powder coated.

      Historically liquid apply methods have been required to coat
such materials.  Use of powder systems present a number of
advantages.  In general liquid overspray cannot be reused, while
oversprayed powder can be.  Furthermore, liquid systems often require
use of hazardous and flammable solvents.

      One method involves backing the thin, nonconductive substrate
with a grounded piece of metal.  When the charged powder is sprayed
at the substrate, it 'sees' the ground potential of the metal plate
through the nonconducting substrate.  Although this technique worked,
it had several disadvantages.

      The subject technique uses two spray streams of oppositely
charged powder.  Each of the streams is directed at opposite sides of
the no...