POWDER COATING APPARATUS AND METHOD OF POWDER COATING USING AN ELECTROMAGNETIC BRUSH
Apparatus and methods for applying powder coatings to a substrate using a magnetic brush developer, including a method and apparatus for applying powder coatings to a substrate either directly or by intermediate transfer using a magnetic brush with a rotating magnetic field and for preparing the coating materials. The apparatus and method includes a supply of prepared powder coating material, a magnetic brush having a rotating magnetic field for applying the powder coating material to the substrate; and an electric field between the magnetic brush having a rotating magnetic field and the substrate.
1 . A layered composite material intended for forming images by electrostatic printing in conjunction with magnetic carrier, comprising:
a. an non-conductive undercoat layer comprising resinous, polymeric toner particles to allow an imaging layer to stick;
b. powder toner applied to the undercoat; and
c. surface coating for treatment of said toner wherein said surface coating comprises nanoparticles tribocharged to opposite polarities from the toner.
2 . The material of claim 1 wherein said polymeric toner particles comprise thermosettable, pigmented particles.
3 . The material of claim 1 wherein said toner particles and said surface coating are applied sequentially in two or more layers after the undercoat.
4 . The material of claim 3 wherein one said layer comprises a rigid material.
5 . The material of claim 4 wherein said rigid material comprises one of a metallic material and a ceramic material.
6 . The material of claim 1 wherein said surface coating comprises sub-micron particles of a transition metal oxide.
7 . The material of claim 1 wherein said toner comprises one or more of the following: silica, alumina, titania, and combinations thereof.
8 . The material of claim 1 wherein said toner comprises metal or metallized flakes compounded w/ resin and combinations thereof.
9 . The material of claim 1 wherein said toner comprises a dispersive catalyst including palladium or platinum and combinations thereof.
10 . The material of claim 1 further comprising a primary filler additive to the toner.
11 . The material of claim 10 , said primary filler additive further comprising a metal oxide has a particle size less then 12 microns to aid in the sequential application of the toner particles.
12 . The material of claim 10 further comprising an optional secondary filler additive to the toner, wherein said secondary filler additive forms a separate layer from the said toner.
13 . The material of claim 12 , the secondary filler additive further comprising an insulator including a ceramics.
14 . A method for forming mixtures of developer material including at least one powder toner component and one magnetic carrier component to provide a homogeneous mixture for use in electrostatic printing, comprising:
a) providing a thermosettable powder paint;
b) grinding the powder paint at low temperatures to form toner particles of less then 12 microns;
c) mixing the toner particles with a surface coating to form a mixture of materials comprising treated toner particles; and
d) combining the treated toner particles and magnetic carrier particles to form a developer material.
15 . The method of claim 14 , wherein the treated toner particles are prepared by regrinding electrostatic spray powder paint at low temperatures.
16 . The method of claim 14 , wherein said surface coating and a binder are tribocharged to opposite polarities when mixed with the toner particles to form the treated toner particles.
17 . The method of claim 14 , said surface coating comprising a charge agent at greater then 1.25 wt %.
18 . The method of claim 14 , further comprising repeating step c one or more times to create coatings having multiple lamina or layers.
19 . The method of claim 18 wherein the multiple lamina include a composite coating made of two layers of the one or more materials applied sequentially.
20 . The method of claim 14 , the mixture comprising an epoxy polyester powder paint recompounded with a charge agent comprising benzyldimethyloctadiecyl ammonium 3-nitrobenzene-sulfonic acid.
21 . A method for preparing developer material to provide a homogeneous mixture for use in electrostatic printing, comprising:
a. recompounding an epoxy polyester powder paint with a charge agent at a temperature of less then 100 degrees F. to form recompounded powder paint;
b. grinding the recompounded powder paint at low temperatures to form toner particles of less then 6 microns;
c. surface treating the toner with a surface treatment to form treated toner particles; and
d. combining said treated toner particles with magnetic carrier particles to form a developer material.
22 . The method of claim 21 , further comprising:
a. recompounding the polyester powder paint with 1.5 pph of chemical charge agent, a zinc complex of ditertbutylsalicylic acid for a charge agent;
b. surface treating the toner with 0.2 wt % colloidal silica such as with 0.2 wt % of R972 silica; and
c. agitating the developer material.
23 . The method of claim 21 , further comprising:
a. recompounding said epoxy polyester powder paint comprising a black commercial styrene butylacrylate polyester powder paint and grinding said paint to form a powder having a volume mean of less than 6 microns;
b. surface treating the toner to form treated toner particles; and
c. admixing said treated toner polymer with a carrier before heating the admixture in an oven to a point sufficient to fuse said treated toner to the carrier.
24 . A layered composite material intended for forming images by electrostatic printing in conjunction with a magnetic carrier, comprising:
a. an non-conductive undercoat layer comprising resinous, polymeric particles to allow a subsequent imaging layer to stick; and
b. a layer of rigid powder toner, wherein the toner comprises a rigid material and polymeric material.
25 . The method of claim 24 , further comprising a surface coating for treatment of said toner wherein said surface coating comprises nanoparticles tribocharged to opposite polarities from said toner.
26 . The material of claim 24 wherein said toner particles comprises thermosettable, pigmented particles.
27 . A method for forming mixtures of developer material including at least one powder toner component and one magnetic carrier component to provide a homogeneous mixture for use in electrostatic printing, comprising:
a) providing a powder paint;
b) grinding the powder paint at low temperatures to form toner particles of less than 6 microns;
c) mixing the toner particles with a surface coating to form a mixture of materials comprising treated toner particles; and
d) combining the treated toner particles and magnetic carrier particles to form a developer material.