U.S. patent application number 17/424643 was filed with the patent office on 2022-03-24 for system for electrocoating conductive substrates.
This patent application is currently assigned to PPG Industries Ohio, Inc.. The applicant listed for this patent is PPG Industries Ohio, Inc.. Invention is credited to Judith A. Bethoski, Mark L. Follet, Amy E. Harrison, Tod M. Hough, Tammy L. Hutchinson, Brent A. Schwartz, Irina G. Schwendeman, Dennis J. Siefer.
Application Number | 20220090288 17/424643 |
Document ID | / |
Family ID | |
Filed Date | 2022-03-24 |
United States Patent
Application |
20220090288 |
Kind Code |
A1 |
Schwartz; Brent A. ; et
al. |
March 24, 2022 |
SYSTEM FOR ELECTROCOATING CONDUCTIVE SUBSTRATES
Abstract
The present invention is directed towards an electrocoating
system comprising a tank comprising at least one sidewall and
configured to hold an electrodepositable coating composition for
receiving a substrate to be coated, and a movable electrode
positioned within the tank, wherein the movable electrode does not
extend through the sidewall. Also disclosed herein are methods of
coating substrates, systems for coating a substrate, and coated
substrates.
Inventors: |
Schwartz; Brent A.;
(Wapakoneta, OH) ; Hutchinson; Tammy L.; (Lima,
OH) ; Hough; Tod M.; (Cheswick, PA) ; Siefer;
Dennis J.; (Findlay, OH) ; Bethoski; Judith A.;
(Pittsburgh, PA) ; Follet; Mark L.; (Allison Park,
PA) ; Schwendeman; Irina G.; (Wexford, PA) ;
Harrison; Amy E.; (Monroeville, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PPG Industries Ohio, Inc. |
Cleveland |
OH |
US |
|
|
Assignee: |
PPG Industries Ohio, Inc.
Cleveland
OH
|
Appl. No.: |
17/424643 |
Filed: |
January 22, 2020 |
PCT Filed: |
January 22, 2020 |
PCT NO: |
PCT/US2020/014650 |
371 Date: |
July 21, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62795654 |
Jan 23, 2019 |
|
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|
International
Class: |
C25D 13/22 20060101
C25D013/22; C25D 3/56 20060101 C25D003/56 |
Claims
1. An electrocoating system comprising: a tank comprising at least
one sidewall and configured to hold an electrodepositable coating
composition for receiving a substrate to be coated, and a movable
electrode positioned within the tank, wherein the movable electrode
does not extend through the sidewall.
2. The electrocoating system of claim 1, further comprising at
least one means for positioning the movable electrode within the
tank.
3. The electrocoating system of claim 1, wherein the movable
electrode comprises an expandable electrode.
4. The electrocoating system of claim 3, wherein the expandable
electrode is positioned on the sidewall and is configured to expand
away from the sidewall.
5. The electrocoating system of claim 3, wherein the tank further
comprises a floor and the expandable electrode is positioned on the
floor, wherein the expandable electrode is configured to expand
away from the floor and does not extend through the floor of the
tank.
6. The electrocoating system of claim 3, further comprising at
least one means for expanding and/or means for retracting the
expandable electrode within the tank.
7. The electrocoating system of claim 6, wherein the means for
expanding and/or means for retracting the expandable electrode
within the tank comprise an apparatus positioned above the tank,
the apparatus having an arm configured to position the expandable
electrode within the tank.
8. The electrocoating system of claim 7, wherein the apparatus
comprises a cart, wherein the cart is positioned on at least one
rail and is laterally moveable on the rail relative to the
tank.
9. The electrocoating system of claim 8, wherein the electrocoating
system further comprises a second cart comprising an arm connected
to the expandable electrode, wherein the first and second carts are
configured to at least partially expand the expandable
electrode.
10. The electrocoating system of claim 9, wherein the system
further comprises a means for further expanding the expandable
electrode.
11. The electrocoating system of claim 6, wherein the means for
expanding and/or means for retracting the expandable electrode
comprises a driving means, wherein the driving means comprises a
rack and pinion, a pneumatic press, a hydraulic press, or a
combination thereof.
12. The electrocoating system of claim 3, wherein the expandable
electrode comprises a telescoping electrode.
13. The electrocoating system of claim 12, wherein at least a
portion of the telescoping electrode is formed of telescoping
sections that may be nested one within another, wherein the
telescoping electrode comprises n telescoping sections each having
a length of X, the telescoping sections allow expanding the length
of the telescoping electrode by a length of up to nX-X, wherein n
is an integer >1.
14. The electrocoating system of claim 3, wherein the expandable
electrode comprises a flexible material comprising a rope or
hose-like configuration.
15. The electrocoating system of claim 1, further comprising a
means for counter-balancing the movable electrode.
16. The electrocoating system of claim 1, further comprising at
least one stationary electrode.
17. The electrocoating system of claim 3, wherein the expandable
electrode further comprises a spacer.
18. The electrocoating system of claim 1, wherein the movable
electrode is located entirely within the tank.
19. The electrocoating system of claim 1, wherein the movable
electrode is completely submerged in the electrodepositable coating
composition.
20. The electrocoating system of claim 1, wherein the movable
electrode has a cross-sectional shape of a triangle, a square, a
rectangle, a pentagon, a hexagon, a heptagon, an octagon, a flat
plate, a C-shape, a fanned shape, or an annular shape.
21. The electrocoating system of claim 1, wherein the movable
electrode is connected to a terminal of a power supply and the
substrate to be coated is connected to a terminal of opposite
polarity of the power supply.
22. A method for coating a substrate using the electrocoating
system of claim 1, the method comprising: positioning the substrate
within the tank wherein a surface of the substrate to be coated is
submerged in the electrodepositable coating composition held in the
tank; positioning the movable electrode; electrically coupling the
movable electrode and the substrate to opposite poles of a power
source; and then applying an electrical current from the power
source to electrodeposit the electrodepositable coating composition
onto the surface of the substrate.
23. The method of claim 22, wherein the substrate comprises a
container having a cavity, and the movable electrode is positioned
in the cavity.
24. The method of claim 22, wherein the movable electrode has an
external surface, and the external surface is at a distance of less
than or equal to four feet from the surface of the substrate to be
coated after the positioning of the movable electrode.
25. The method of claim 22, further comprising at least one of:
pretreating the substrate prior to processing the substrate in the
electrocoating system; priming the substrate prior to processing
the substrate in the electrocoating system; and/or applying a
topcoat coating to the substrate after processing the substrate in
the electrocoating system.
26. A substrate coated by the method of claim 22.
27. A system for coating a substrate comprising the electrocoating
system of claim 1 and further comprising at least one of: a
pretreatment system for pretreating the substrate prior to
processing the substrate in the electrocoating system; a priming
system for priming the substrate prior to processing the substrate
in the electrocoating system; and/or a topcoat system for applying
a topcoat coating to the substrate after processing the substrate
in the electrocoating system.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to electrocoating systems for
electrocoating a substrate. The present invention also relates to a
system for coating substrates, methods for coating substrates, and
coated substrates.
BACKGROUND INFORMATION
[0002] Electrodeposition as a coating application method involves
the deposition of a film-forming composition onto a conductive
substrate under the influence of an applied electrical potential.
Electrodeposition has gained popularity in the coatings industry
because it provides higher paint utilization, outstanding corrosion
resistance, and low environmental contamination as compared with
non-electrophoretic coating methods. However, some conductive
substrates are more difficult to coat by electrodeposition because
of a number of factors, including the shape and size of the
substrate. For example, it may be difficult to coat both the
internal and external surfaces of substrates having an open-pocket
shape, such as a container or a pipe, using conventional
electrocoat systems. Therefore, an electrocoating system that is
capable of coating a wide range of substrates is desired.
SUMMARY OF THE INVENTION
[0003] Disclosed herein is an electrocoating system comprising a
tank comprising at least one sidewall and configured to hold an
electrodepositable coating composition for receiving a substrate to
be coated, and a movable electrode positioned within the tank,
wherein the movable electrode does not extend through the
sidewall.
[0004] Also disclosed herein is a method for coating a substrate
comprising electrophoretically applying an electrodepositable
coating composition to at least a portion of the substrate using
the electrocoating system of the present invention. This method
comprises positioning the substrate within the tank wherein a
surface of the substrate to be coated is submerged in the
electrodepositable coating composition held in the tank;
positioning the movable electrode; electrically coupling the
movable electrode and the substrate to opposite poles of a power
source; and then applying an electrical current from the power
source to electrodeposit the electrodepositable coating composition
onto the surface of the substrate.
[0005] Further disclosed herein are substrates coated by the method
of the present invention.
[0006] Still further disclosed herein is a system for coating a
substrate comprising the electrocoating system of the present
invention, and further comprising at least one of: a pretreatment
system for pretreating the substrate prior to processing the
substrate in the electrocoating system; a primer system for
applying a primer to the substrate prior to processing the
substrate in the electrocoating system; and/or a topcoat system for
applying a topcoat coating to the substrate after processing the
substrate in the electrocoating system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIGS. 1A and 1B is a top view of an exemplary electrocoating
system of the present invention with a movable electrode in a first
position in FIG. 1A and the movable electrode in a second position
in FIG. 1B. FIGS. 1C and 1D is a side view of an exemplary
electrocoating system of the present invention with a movable
electrode in a first position in FIG. 1C and the movable electrode
in a second position in FIG. 1D.
[0008] FIG. 2A is an illustration of an exemplary electrocoating
system of the present invention with an expandable electrode in a
first state in a tank with a substrate to be coated. FIG. 2B is an
illustration of the exemplary electrocoating system of FIG. 2A with
the expandable electrode in an expanded state.
[0009] FIG. 3A is a perspective view of an exemplary electrocoating
system of the present invention with an expandable electrode in a
first state present in a tank. FIG. 3A further shows a first
apparatus having an arm connected to the expandable electrode and
two legs positioned along a set of rails running along both sides
of the bottom of the tank, and a second apparatus also having a
second arm connected to another section of the expandable electrode
and two legs positioned along a second set of rails running along
both sides of the bottom of the tank. FIG. 3B is a top view of the
exemplary electrocoating system shown in FIG. 3A, and FIG. 3C is a
sideview of the exemplary electrocoating system shown in FIG.
3A.
[0010] FIG. 4A is a perspective view of an exemplary electrocoating
system of the present invention with the expandable electrode in a
partially expanded state. FIG. 4B is a top view of the exemplary
electrocoating system shown in FIG. 4A, and FIG. 4C is a side view
of the exemplary electrocoating system shown in FIG. 4A.
[0011] FIG. 5A is a perspective view of an exemplary electrocoating
system of the present invention with the expandable electrode in a
fully expanded state. FIG. 5B is a top view of the exemplary
electrocoating system shown in FIG. 5A, and FIG. 5C is a side view
of the exemplary electrocoating system shown in FIG. 5A.
[0012] FIG. 6A is a perspective view of an exemplary electrocoating
system of the present invention with an expandable electrode
wrapped completely around a reel, and a substrate present in the
tank. FIG. 6B is a perspective view showing the expandable
electrode partially inserted through the substrate, with the dotted
line indicating the expandable electrode is inside the substrate.
FIG. 6C is a perspective view showing the expandable electrode
fully expanded through the substrate and secured to a sidewall
using an anchor, with the dotted line indicating the expandable
electrode is inside the substrate.
[0013] FIG. 6D is a perspective view of an exemplary expandable
electrode having a spacer. FIG. 5E is an inline view of the
exemplary expandable electrode having a spacer.
[0014] FIG. 6F is a perspective view of an exemplary electrocoating
system of the present invention with an expandable electrode having
a spacer positioned within a substrate present in the tank.
[0015] FIG. 7A is an illustration of an exemplary electrocoating
system of the present invention with an expandable electrode
positioned on the floor of a tank in a first state with a substrate
to be coated. FIG. 7B is an illustration of the exemplary
electrocoating system of FIG. 7A with the expandable electrode in a
partially expanded state. FIG. 7C is an illustration of the
exemplary electrocoating system of FIG. 7A with the expandable
electrode in a fully expanded state.
DETAILED DESCRIPTION OF THE INVENTION
[0016] The present invention is directed to an electrocoating
system for electrocoating a substrate. The present specification
also discloses systems for coating a substrate, methods for coating
substrates, substrates coated in accordance with one or more of the
methods described herein, and/or through the use of one or more of
the systems described herein.
Electrocoating System
[0017] As shown for illustration purposes in FIGS. 1A and 1B, the
present invention is directed to an electrocoating system 10
comprising a tank 100 comprising at least one sidewall 120 and
configured to hold an electrodepositable coating composition 900
for receiving a substrate 1000 to be coated, and a movable
electrode 200 positioned within the tank 100, wherein the movable
electrode 200 does not extend through the sidewall 120. As used
herein, the term "movable electrode" refers to an electrode that is
configured to change its position and/or orientation in the tank.
The movement may be actual movement of the movable electrode 200 or
by a change in the configuration of the movable electrode 200. For
example, the movable electrode 200 may comprise an expandable
electrode 200, as discussed in more detail below. Alternatively,
the movable electrode 200 may comprise a means for positioning 300
the movable electrode in the tank, and the means for positioning
300 may allow for the movement of the movable electrode.
[0018] According to the present invention, and as shown in the
Figures, the tank 100 is configured to hold an electrodepositable
coating composition 900. The tank 100 may comprise any material
known in the art. For example, the tank 100 may comprise plastic,
metal having an insulating liner such as metal having an internal
plastic or fiberglass liner, or metal having an insulating coating.
The tank 100 may comprise any geometric shape. For example, the
tank 100 may be generally rectangular or generally round or
spherical. The tank 100 may comprise a floor 110 and at least one
sidewall 120, such as four sidewalls as in case of the depicted
exemplary rectangular configuration, extending up from the floor
110 to form a cavity within which the electrodepositable coating
composition 900 may be held.
[0019] The movable electrode 200 may comprise any suitable
conductive material known in the art, and the movable electrode 200
may comprise both conductive and non-conductive materials. For
example, the movable electrode 200 may comprise any other materials
that may comprise the substrate, as described herein, as well as
ruthenium oxide. The movable electrode 200 may optionally comprise
or be made of a non-porous material. As used herein, the term
"non-porous" generally refers to materials that are not permeable
to fluids such as water or air.
[0020] The movable electrode 200 may have any cross-sectional
shape. For example, the movable electrode 200 may have the shape of
any polygon, such as a triangle, square, rectangle, pentagon, and
the like, a flat plate, a C-shape, a fanned shape, annular shape,
as well as a generally round shape, such as tubular movable
electrodes having a circular or oval cross-sectional shape. The
cross-sectional shape of the movable electrode 200 may be selected
based upon a number of factors, such as, for example, the surface
area of the substrate 1000 to be electrocoated, the relative
surface area of the movable electrode 200 relative to the surface
area of the substrate 1000 to be coated, the distance between the
movable electrode 200 and substrate 1000 during electrocoating, and
the shape of the substrate 1000.
[0021] The cross-sectional area of the movable electrode 200 is not
particularly limited and may depend upon and/or be proportional to
the size of the substrate 1000 to be coated. For example, substrate
having large cross-sectional areas may require a movable electrode
200 having a larger cross-sectional area. In addition, the
cross-sectional shape of the movable electrode 200 may be selected
based upon the shape of the substrate 1000 to be coated. For
example, a movable electrode 200 may have a cross-sectional shape
that mirrors the cross-sectional shape of the substrate 1000 to be
coated. In addition, the cross-sectional area of the movable
electrode 200 may be such that the external surface of the movable
electrode 200 is within four feet of the surface of the substrate
1000 to be coated. For example, an exemplary movable electrode 200
having a square cross-sectional shape and a cross-sectional area of
at least 19.01 ft.sup.2 (1.77 m.sup.2) may be used to coat an
exemplary substrate 1000 having a square cross-sectional shape and
a cross-sectional area of 100 ft.sup.2 (9.29 m.sup.2).
[0022] The leading (or terminal) edge of the movable electrode 200
may optionally comprise one or more protrusions that extend from
the leading edge of the movable electrode 200. The protrusions may
extend into harder to reach portions of the substrate 1000 to be
coated, such as complex geometries or the corners of a square or
rectangular shaped substrate 1000. This may improve the charge
density of the electrodepositable coating composition 900 in such
corners and improve the deposition of the electrodepositable
coating composition 900 in such corners.
[0023] The movable electrode 200 may be configured to be free of
contact points with the substrate 1000 to be coated. As used
herein, the term "contact point" with reference to the movable
electrode 200 and substrate 1000 refers to physical contact between
the movable electrode 200 and substrate 1000 such that there is a
void present between the substrate 1000 and the movable electrode
200 that may be filled with the electrodepositable coating
composition 900. The term "contact point" explicitly excludes
electrical communication between the components.
[0024] The movable electrode 200 may be positioned in the tank 100
such that the entire movable electrode 200 is submerged in an
electrodepositable coating composition 900 when the tank 100 is at
least partially filled. The movable electrode 200 may be configured
such that the movable electrode 200 does not extend through the
floor 110 or a sidewall 120 of the tank 100. As used herein, the
term "through" with respect to the floor 100 or sidewall 120 of the
tank 100 means that the movable electrode 200 does not extend
through any opening located in the floor 110 or sidewall 120 of the
tank 100 such that a portion of the movable electrode 200 is
positioned outside of the tank 100.
[0025] The movable electrode 200 comprises a surface and the
surface may be essentially free of electrocatalyst. As used herein,
the term "electrocatalyst" refers to those used in electrochemical
ozone generating systems, such as, for example, lead dioxide.
[0026] As shown in FIGS. 1 and 2, the means for positioning 300 the
movable electrode 200 within the tank 100 may comprise one or more
apparatus(es) 310 positioned outside of the tank 100, and the
apparatus(es) 310 may comprise an arm connected to the movable
electrode 200 and configured to position the movable electrode 200
within the tank 100. The apparatus 310 may have any configuration
and be positioned anywhere outside the tank 100 as long as the arm
is configured to extend into the tank 100 to position the movable
electrode 200. For example, as shown in FIGS. 1A and 1B, the
apparatus 310 may comprise a cart 330, and the cart 330 may be
positioned on at least one rail 350 such that the cart is laterally
moveable on the rail 350 relative to the tank 100. The rail 350 may
be positioned above, beside or under the tank 100. For example, in
FIGS. 1A and 1B, two rails 350 are positioned on the top of
opposite sidewalls 120 of the tank 100 with each rail (350 and 370)
supporting a cart 330 that is connected to either side of the
apparatus 310. The means for positioning 300 the movable electrode
200 in FIGS. 1A and 1B move the movable electrode 200 from a first
position (FIG. 1A) to a second position (FIG. 1B) by moving the
carts 330 along the rails 350. The means for positioning 300 may
comprise any means known in the art, such as, for example, a rack
and pinion, a pneumatic press, a hydraulic press, a chain and the
like, or a combination thereof. The means for positioning 300 the
movable electrode 200 may further comprise a means for moving the
movable electrode in a vertical direction relative to the tank (not
shown). The means for moving in a vertical direction may comprise
any means known in the art, such as, for example, a rack and
pinion, a pneumatic press, a hydraulic press, a chain and the like,
or a combination thereof.
[0027] The electrocoating system 10 may comprise a means for
positioning and/or rotating the substrate 1000 (not shown). The
means for positioning and/or rotating the substrate 1000 allow for
the substrate 1000 to be positioned into the tank 100. The means
for positioning and/or rotating the substrate 1000 may further
allow for the substrate 1000 to be tipped and/or rotated along its
length in order to allow any air trapped in the substrate 1000 to
escape such that all or substantially all of the surface of the
substrate 1000 is in contact with the electrodepositable coating
composition 900 contained within the tank 100. The tipping may be,
for example, about 5.degree. relative to the main axis along the
length of the substrate 1000, and may be rotated, for example,
about 15.degree. around the main axis along the length of the
substrate 1000. The tipping and/or rotating of the substrate 1000
may occur before operation of the electrocoating system 10 or
during operation of the electrocoating system 10. In addition, the
movable electrode 200 may be configured to mirror the rotation of
the substrate 1000 during operation of the electrocoating system 10
to ensure that the movable electrode 200 maintains constant
distance from the surface of the substrate 1000 during
operation.
[0028] The means for positioning and/or rotating the substrate 1000
may comprise a Roll Over Dip (or RoDip) system wherein the
substrate 1000 is positioned on a conveyer above the tank 100, and
the conveyer rotates the substrate 1000 and allows it to be dipped
(i.e., submerged) into the electrodepositable coating composition
900 held within the tank 100 of the electrocoating system 10. The
movable electrode 200 may be moved into position while the conveyer
is rotating the substrate 1000, and the electrocoating system 10
may optionally be operated with the substrate 1000 being rotated by
the RoDip system, and the movable electrode 200 may also optionally
be rotated.
[0029] As discussed above, the movable electrode 200 may comprise
an expandable electrode 200. As shown for illustration purposes in
FIGS. 2A and 2B, the present invention is directed to an
electrocoating system 10 comprising a tank 100 configured to hold
an electrodepositable coating composition 900 for receiving a
substrate 1000 to be coated, and an expandable electrode 200
positioned within the tank 100. The expandable electrode 200 is
configured to expand from a first state (FIG. 2A) to an expanded
state (FIG. 2B).
[0030] According to the present invention, and as shown in FIGS. 2A
and 2B, the electrocoating system 10 further comprises an
expandable electrode 200 positioned within the tank 100. The
expandable electrode 200 may be configured to be expanded from a
first state, as shown in FIG. 2A, to an expanded state, as shown in
FIG. 2B. As used herein, the term "expandable electrode" refers to
an electrode having a dimension that can non-destructively be
increased in at least one spatial direction. As used herein, the
terms "expand", "expanding", "expandable" and the like refer to an
increase in the dimension of a body in at least one spatial
direction, and includes bodies that increase their length through a
change in structure (e.g., a telescoping mechanism or an unwinding
mechanism). The term "expandable electrode" does not include
unitary materials that may expand due to the application of an
external energy force, such as, e.g., a metal expanding due to the
application of heat. The expandable electrode configuration is not
limited as long as the expandable electrode is configured to expand
in length. A portion or substantially all of the expandable
electrode 200 may comprise a material that expands by a change in
the configuration of the material, such as, for example, a
telescoping section, an accordion-like section, a spring-shaped
section, and the like. Alternatively, the expandable electrode 200
may comprise a flexible material capable of having its positioning
expanded within the tank 100 without the length of the expandable
electrode material itself changing, such as, for example, a rope or
hose-like configuration that may be rolled up in a first state and
unrolled in the tank 100 to expand the length of the expandable
electrode 200 to an expanded state, and like structures.
[0031] The expandable electrode may also comprise combinations of
the above described mechanisms, including combinations of
telescoping sections, accordion-like configured sections,
spring-shaped sections, and flexible materials. The expansion of
the expandable electrode 200 may be along a generally linear path,
such as in FIGS. 2A and 2B, but expansion along a non-linear path,
as well as branching of the expandable electrode are also within
the scope of the invention. For example, the expandable electrode
200 may expand in a generally linear path with multiple branches
extending out from the direction of expansion of the main portion
of the expandable electrode 200, such as in a generally
perpendicular direction. Alternatively, the expandable electrode
may branch into two or more directions, such as a fork
configuration.
[0032] As shown in FIGS. 2A and 2B, the expandable electrode 200
may comprise a telescoping electrode 210. The telescoping electrode
210 may comprise telescoping sections 220 that may be nested one
within another when the expandable electrode 200 is not fully
expanded. The telescoping sections 220 may comprise a portion or
all of the telescoping electrode 210. The telescoping sections 220
of the telescoping electrode 210 may each have a substantially
uniform length of expansion, X, and the telescoping sections 220
may expand the length of the telescoping electrode 210 by up to
nX-X, wherein n is an integer >1 and equal to the total number
of telescoping sections 220. As used herein, the term "length of
expansion" with respect to a telescoping section 220 refers to the
maximum amount an additional telescoping section 220 will be able
to increase the length of the telescoping electrode 210. Although
the maximum expanded length of the telescoping electrode 210 is nX,
the expanded length in practice may be any length greater than X to
nX, depending upon the desired application and the substrate 1000
to be coated by the electrocoating system 10. The expansion of the
telescoping electrode 210 may include expansion of telescoping
sections 220 one at a time such that one telescoping section 220
"un-nests" at a time, the telescoping sections 220 may move all at
once such that each telescoping section 220 remains partially
nested at an expanded length, or a combination of the two.
[0033] The expandable electrode 200 may be fixedly positioned
entirely within the tank such that the entire expandable electrode
200 is submerged in the electrodepositable coating composition 900.
As used herein, an expandable electrode 200 is fixedly positioned
entirely within the tank 100 when the expandable electrode 200 is
secured to a portion of the tank 100 without further structures
located outside the tank 100 supporting the positioning of the
expandable electrode 200. For example, as shown in FIGS. 2A and 2B,
the expandable electrode 200 may be fixedly positioned on a
sidewall 120 of the tank 100 and may expand in a direction away
from the sidewall 120. Alternatively, as shown in FIGS. 7A, 7B and
7C, the expandable electrode 200 may be positioned on the floor 110
of the tank 100 and may expand in a direction away from the floor
110. The configuration of the expandable electrode 200 may depend
upon the application and the substrate 1000 to be coated by the
electrocoating system 10.
[0034] According to the present invention, the electrocoating
system 10 may comprise a means for positioning 300 the expandable
electrode 200 within the tank 100. The means for positioning 300
the expandable electrode 200 within the tank 100 generally refers
to a supporting structure connected to the expandable electrode 200
to provide support that is located at least partially outside of
the tank 100. As used herein, the term "at least partially outside
of the tank" with respect to a structure refers to a structure that
is not submerged in the electrodepositable coating composition 900
when the tank 100 is filled to its maximum level. The means for
positioning 300 the expandable electrode 200 within the tank 100
may comprise one or more apparatus(es) 310 positioned outside of
the tank 100, and the apparatus(es) 310 may comprise an arm
connected to the expandable electrode 200 and configured to
position the expandable electrode 200 within the tank 100. The
apparatus 310 may have any configuration and be positioned anywhere
outside the tank 100 as long as the arm is configured to extend
into the tank 100 to position the expandable electrode 200. For
example, as shown in FIGS. 3A, 3B, 3C, 4A, 4B, 4C, 5A, 5B and 5C
(collectively, "FIGS. 3-5"), the apparatus 310 may comprise a cart
330, and the cart 330 may be positioned on at least one rail 350
such that the cart is laterally moveable on the rail 350 relative
to the tank 100. The rail 350 may be positioned above, beside or
under the tank 100. For example, in FIGS. 3-5, two rails (350 and
370) are positioned on the bottom of opposite sidewalls 120 of the
tank 100 with each rail (350 and 370) supporting one of the two
legs 380 of one of the carts 330 and 340. The means for positioning
the expandable electrode 200 within the tank 100 may also function
to at least partially or fully expand the expandable electrode 200.
For example, in FIGS. 3-5, a first cart 330 and a second cart 340
are configured to position the expandable electrode 200 within the
tank 100. In FIGS. 3-5, the first cart 330 and second cart 340 each
comprise an arm 320, with the arm 320 of the first cart 330
attached to the end of the expandable electrode 200 and the arm 320
of the second cart 340 attached to a telescoping section 220 of the
expandable electrode 200. FIGS. 3A, 3B, and 3C show perspective,
top and side views, respectively, of the first cart 330 and second
cart 340 as positioned in a first (starting) state. FIGS. 4A, 4B,
and 4C show perspective, top and side views, respectively, of the
expandable electrode 200 in a partially expanded state with the
second cart 340 having moved laterally away from the first cart 330
and positioning the expandable electrode 200 further in the tank
100 relative to the first state. The expansion of the expandable
electrode 200 into the tank may be at least partially or fully
caused by the movement of the second cart 340 if the second cart
340 causes the length of the expandable electrode 200 to increase.
FIGS. 5A, 5B, and 5C show perspective, top and side views,
respectively, of the first cart 330 moved laterally towards the
second cart 340 to position the expandable electrode 200 in a fully
expanded state further into the tank 100. The means for positioning
300 the expandable electrode 200 may further comprise a means for
moving the expandable electrode in a vertical direction relative to
the tank (not shown). The means for moving in a vertical direction
may comprise any means known in the art, such as, for example, a
rack and pinion, a pneumatic press, a hydraulic press, a chain and
the like, or a combination thereof.
[0035] According to the present invention, the electrocoating
system 10 may further comprise a means for expanding 400 the
expandable electrode 200. The means for expanding 400 the
expandable electrode 200 may comprise any suitable means known in
the art. For example, as described above, the means for expanding
400 may comprise an apparatus 310 located outside of the tank 100
that moves the expandable electrode 200 into an expanded state,
i.e., increases the length of the expandable electrode 200. The
means for expanding 400 the expandable electrode 200 into an
expanded state may alternatively comprise a driving means, and the
driving means may comprise a rack and pinion, a pneumatic press, a
hydraulic press, a chain and the like, or a combination thereof.
Such means for expanding 400 the expandable electrode 200 may be
used in combination with any appropriate configuration of the
expandable electrode 200, such as a telescoping electrode, an
electrode having an accordion-like configuration, and the like. The
means for expanding 400 the expandable electrode 200 into an
expanded state may also comprise multiple means for expanding the
expandable electrode 200. For example, the means for expanding 400
the expandable electrode 200 may comprise an apparatus 310 located
outside of the tank 100 that moves the expandable electrode 200
into a partially expanded state, as described above, and the
electrocoating system 10 may comprise a further means for expanding
500 the expandable electrode 200 which may comprise a rack and
pinion, a pneumatic press, a hydraulic press, and the like, or a
combination thereof, that expands the expandable electrode 200 into
a further or fully expanded state.
[0036] The means for expanding 400 the expandable electrode 200 may
also comprise a means for moving a flexible material within the
tank. For example, the flexible material may be connected to an
extendable arm that may extend the material of the expandable
electrode 200 in the tank 100. Alternatively, the flexible material
may be connected to a runner that allows for the flexible material
of the expandable electrode 200 to be carried into the tank 100.
The flexible material of the expandable electrode 200 may be held
taut in the tank 100 by any suitable means, including, for example,
attachment to an anchor (not shown) present on an opposite sidewall
120 of the tank. The flexible material of the expandable electrode
200 may be especially suitable for coating long hollow substrates,
such as, for example, a pipe. The flexible material of the
expandable electrode 200 may be strung through the length of the
pipe and secured to an anchor to hold the expandable electrode 200
in a taut generally uniform distance from the interior surface of
the pipe. In such configuration, as shown in FIGS. 6A, 6B, 6C and
6F, the expandable electrode 200 may be present on a reel 210
positioned inside the tank 100, and the expandable electrode 200
may be unrolled from the reel 210 to extend through the hollow
substrate 1000. An anchor 220 may be positioned on a sidewall 120
of the tank 100 to secure the expandable electrode 200 in
place.
[0037] The electrocoating system 10 may further comprise a means
for retracting 600 the expandable electrode 200. Any suitable means
for retracting 600 the expandable electrode may be used. For
example, the means for retracting 600 the expandable electrode 200
may comprise the reverse motion of the means for expanding 400 the
expandable electrode 200, such as reversing the direction of force
of the driving means. In another example, as shown in FIGS. 3-5,
the means for retracting 600 the expanded electrode 200 may
comprise a return chain 610 that applies a force to at least
partially reduce expansion of the expandable electrode 200.
[0038] As mentioned above, the expandable electrode 200 may
comprise a flexible material capable of having its positioning
expanded within the tank 100 without the length of the expandable
electrode material changing. In such configuration, as shown in
FIGS. 6A, 6B, 6C and 6F, the means for retracting 600 the
expandable electrode 200 may comprise a mechanism such as winding
the reel 210 to retract the expandable electrode 200.
[0039] The retraction of the expandable electrode 200 may occur
during electrodeposition such that the expandable electrode 200
applies a charge to and deposits the electrodepositable coating
composition 900 onto a portion of the substrate 1000 as the
expandable electrode 200 moves past the portion of the substrate
1000.
[0040] As shown in FIGS. 6D and 6E, the expandable electrode 200
may optionally comprise a spacer 230 positioned on the expandable
electrode 200. The spacer 230 may be sized and configured in such a
way that the expandable electrode 200 is maintained at a constant
distance from the internal surface of the substrate 1000. For
example, if the substrate 1000 is a round pipe, the spacer 230
would contact the internal surface of the substrate 1000 to
maintain the expandable electrode equidistant from each portion of
the cross-section of the internal surface of the substrate 1000. As
shown in FIGS. 6D, 6E and 6F, the charged portion 250 of the
expandable electrode 200 may be positioned at the terminus of the
expandable electrode 200 after the spacer 230 such that the charge
is applied to portions of the substrate 1000 as the charged portion
250 of the expandable electrode 200 passes through the substrate
during electrodeposition. The charged portion 250 of the expandable
electrode 200 may optionally be positioned behind the spacer 230
such that the charged portion 250 provides a charge to portions of
the substrate 1000, and accordingly electrodeposits the
electrodepositable coating composition 900, after the spacer 230
has moved past said section of the substrate 1000. This
configuration may prevent the spacer 230 from producing defects in
the applied coating while it moves through and potentially contacts
the first surface 1010 of the substrate 1000.
[0041] The electrocoating system 10 may further comprise a means
for counter-balancing 700 the movable electrode 200. Any suitable
means for counter-balancing 700 may be used. For example, the means
for counter-balancing 700 may comprise one or more air bladders or
low-density materials, such as foam, attached to, or located
within, the movable electrode 200 body that increase the buoyancy
of the movable electrode 200 in the electrodepositable coating
composition 900, as well as mechanical means for counter-balancing
700 the movable electrode 200, such as the spacer 230 described
herein. The means for counter-balancing 700 the movable electrode
200 is meant to prevent sagging of the movable electrode 200
relative to the substrate 1000 that may result from the length of
the movable electrode 200, including the length of the expandable
electrode 200 in an expended state. The counter-balancing assists
in ensuring uniform distance between the outer surface of the
movable electrode 200 and the surface of the substrate 1000 that
allows for the substrate 1000 to be coated substantially uniform.
Accordingly, the means for counter-balancing 700 may help improve
the uniformity of the charge density of the electrodepositable
coating composition 900 during electrocoating as well as eliminate
arcs that may result from contact of the movable electrode 200 with
the substrate 1000 to be coated.
[0042] The tank 100 is also configured to contain, at least
partially, a substrate 1000 for electrocoating by the
electrocoating system 10. The substrate 1000 may be a grounded
electrical conductor and may generally be substantially configured
of a conductive substance, such as, for example, a metallic
substance. The substrate 1000 serves as a counter-electrode in
electrical communication with the stationary electrode(s) 800 (if
present) and movable electrode(s) 200. The substrate 1000 may
comprise any cross-sectional shape, or multiple cross-sectional
shapes if the substrate 1000 does not have a uniform
cross-sectional shape. The substrate may comprise any dimensions.
The substrate 1000 may comprise an open-polygon cross-sectional
shape, such as an open-pocket cross-sectional shape. The
cross-sectional shape may comprise a generally rectangular or a
generally round cross-sectional shape. The substrate may comprise a
first surface 1010 and a second surface 1020. The first surface
1010 may comprise an internal surface of the substrate 1000, and
the second surface 1020 may comprise an external surface of the
substrate 1000. For example, as shown in FIGS. 2A and 2B, when the
substrate 1000 has a generally rectangular cross-sectional shape,
the first surface 1010 may comprise the internal surface of the
substrate 1000, and the second surface 1020 may comprise the
external surface of the substrate 1000. The substrate 1000 may
comprise a container, such as, for example, an intermodal
container. For example, the substrate 1000 may have an external
length of about 8 feet (2.44 m) to about 53 feet (16.15 m), such as
8 feet (2.44 m), 10 feet (3.05 m), 20 feet (6.10 m), 40 feet (12.19
m), 45 feet (13.72 m) or 53 feet (16.15 m); an external width of
about 7 feet (2.13 m) to about 8 feet (2.44 m), such as 7 feet
(2.13 m) or 8 feet (2.44 m); and an external height of about 7.5
feet (2.29 m) to about 9.5 feet (2.90 m), such as 7.5 feet (2.29
m), 8.5 feet (2.59 m) or 9.5 feet (2.90 m). The substrate 1000 may
have a length of at least 8 feet (2.44 m), such as at least 10 feet
(3.05 m), such as at least 20 feet (6.10 m), such as at least 40
feet (12.19 m), such as at least 45 feet (13.72 m) or such as at
least 53 feet (16.15 m).
[0043] The first surface 1010 of the substrate 1000 may have a
surface area that varies based on the length of the substrate 1000.
The first surface 1010 of the substrate 1000 may have a surface
area of at least 285 ft.sup.2 (26.48 m.sup.2), such as at least 340
ft.sup.2 (31.59 m.sup.2), such as at least 600 ft.sup.2 (55.74
m.sup.2), such as at least 1,145 ft.sup.2 (106.37 m.sup.2), such as
at least 1,275 ft.sup.2 (118.45 m.sup.2), such as at least 1,490
ft.sup.2 (138.43 m.sup.2). The first surface 1010 of the substrate
1000 may have a surface area of 285 ft.sup.2 (26.48 m.sup.2) to
1,890 ft.sup.2 (175.59 m.sup.2) or larger. With respect to a
container, the surface area may vary depending upon the length of
the substrate 1000. For example, the first surface 1010 of an
8-foot substrate 1000 may have a surface area of 285 ft.sup.2
(26.48 m.sup.2) to 400 ft.sup.2 (37.16 m.sup.2), the first surface
1010 of a 10-foot substrate 1000 may have a surface area of 340
ft.sup.2 (31.59 m.sup.2) to 460 ft.sup.2 (42.74 m.sup.2), the first
surface 1010 of a 20-foot substrate 1000 may have a surface area of
600 ft.sup.2 (55.74 m.sup.2) to 795 ft.sup.2 (73.86 m.sup.2), the
first surface 1010 of a 40-foot substrate 1000 may have a surface
area of 1,145 ft.sup.2 (106.37 m.sup.2) to 1,460 ft.sup.2 (135.64
m.sup.2), the first surface 1010 of a 45-foot substrate 1000 may
have a surface area of 1,275 ft.sup.2 (118.45 m.sup.2) to 1,620
ft.sup.2 (150.50 m.sup.2), and the first surface 1010 of a 53-foot
substrate 1000 may have a surface area of 1,490 ft.sup.2 (138.43
m.sup.2) to 1,890 ft.sup.2 (175.59 m.sup.2).
[0044] The second surface 1020 of the substrate 1000 may have a
surface area that varies based on the length of the substrate 1000.
The second surface 1020 of the substrate 1000 may have a surface
area of at least such as at least 330 ft.sup.2 (30.66 m.sup.2), 380
ft.sup.2 (35.30 m.sup.2), such as at least 675 ft.sup.2 (62.71
m.sup.2), such as at least 1,250 ft.sup.2 (116.13 m.sup.2), such as
at least 1,390 ft.sup.2 (129.14 m.sup.2), such as at least 1,630
ft.sup.2 (151.43 m.sup.2). The second surface 1020 of the substrate
1000 may have a surface area of 330 ft.sup.2 (30.66 m.sup.2) to
1,750 ft.sup.2 (162.58 m.sup.2) or larger. With respect to a
container, the surface area may vary depending upon the length of
the substrate 1000. For example, the second surface 1020 of an
8-foot substrate 1000 may have a surface area of 330 ft.sup.2
(30.66 m.sup.2) to 440 ft.sup.2 (40.88 m.sup.2), the second surface
1020 of a 10-foot substrate 1000 may have a surface area of 380
ft.sup.2 (35.30 m.sup.2) to 520 ft.sup.2 (48.31 m.sup.2), the
second surface 1020 of a 20-foot substrate 1000 may have a surface
area of 675 ft.sup.2 (62.71 m.sup.2) to 865 ft.sup.2 (80.36
m.sup.2), the second surface 1020 of a 40-foot substrate 1000 may
have a surface area of 1250 ft.sup.2 (116.13 m.sup.2) to 1,575
ft.sup.2 (146.32 m.sup.2), the second surface 1020 of a 45-foot
substrate 1000 may have a surface area of 1,390 ft.sup.2 (129.14
m.sup.2) to 1,750 ft.sup.2 (162.58 m.sup.2), and the second surface
1020 of a 53-foot substrate 1000 may have a surface area of 1,630
ft.sup.2 (151.43 m.sup.2) to 2,030 ft.sup.2 (188.59 m.sup.2).
[0045] The substrate 1000 may have a cross-sectional area of at
least 40 ft.sup.2 (3.72 m.sup.2), such as at least 45 ft.sup.2
(4.18 m.sup.2), such as at least 50 ft.sup.2 (4.65 m.sup.2), and
may be no more than 100 ft.sup.2 (9.30 m.sup.2), such as no more
than 85 ft.sup.2 (7.90 m.sup.2), such as no more than 81 ft.sup.2
(7.53 m.sup.2). The substrate 1000 may have a cross-sectional area
of 40 ft.sup.2 (3.72 m.sup.2) to 100 ft.sup.2 (9.30 m.sup.2), such
as 45 ft.sup.2 (4.18 m.sup.2) to 85 ft.sup.2 (7.90 m.sup.2), such
as 50 ft.sup.2 (4.65 m.sup.2) to 81 ft.sup.2 (7.53 m.sup.2). As
used herein, the term "cross-sectional area" with respect to the
substrate 1000 refers to the largest cross-sectional area of the
substrate as measured perpendicular to the longest axis of the
substrate 1000. With respect to a container-shaped substrate 1000,
the cross-sectional area will be the width multiplied by the
height.
[0046] The substrate 1000 may comprise any conductive material. For
example, the substrate 1000 may comprise a metal, metal alloy,
and/or materials that have been metallized, such as nickel-plated
plastic. Additionally, substrate 1000 may comprise non-metal
conductive materials including composite materials such as, for
example, materials comprising carbon fibers or conductive carbon.
The metal or metal alloy may comprise, for example, cold rolled
steel, hot rolled steel, steel coated with zinc metal, zinc
compounds or zinc alloys, such as electrogalvanized steel,
hot-dipped galvanized steel, galvanealed steel, nickel-plated
steel, and steel plated with zinc alloy. The substrate 1000 may
comprise an aluminum alloy. Non-limiting examples of aluminum
alloys include the 1XXX, 2XXX, 3XXX, 4XXX, 5XXX, 6XXX, 7XXX or 8XXX
series as well as clad aluminum alloys and cast aluminum alloys.
The substrate 1000 may comprise a magnesium alloy. The substrate
1000 used in the present invention may also comprise other suitable
non-ferrous metals such as titanium or copper, as well as alloys of
these materials.
[0047] When the substrate 1000 is positioned at least partially
inside the tank 100, the electrocoating system 10 may be configured
such that the movable electrode 200 may be moved into a position
generally closer to the substrate 1000. For example, as discussed
above, the distance between the external surface of the movable
electrode 200 may be at a distance of four feet or less from the
surface of the substrate 1000 to be coated. For example, if the
substrate 1000 comprises a cavity, such as a container or a pipe,
the movable electrode 200 may positioned (or expanded) into the
cavity of the substrate 1000 to be coated.
[0048] The electrocoating system 10 may further comprise at least
one power source (not shown) to provide an electrical current to
the electrocoating system 10. The power source may optionally
include a rectifier. The power source is electrically coupled to
the movable electrode 200, the substrate 1000, and, if present, the
stationary electrodes 800, with one pole of the power source
coupled to the substrate, and the other pole of the power source
coupled to the movable electrode 200 and, if present, the
stationary electrode(s) 800, such that the substrate 1000 serves as
a counter-electrode to the movable electrode 200 and, if present,
the stationary electrode(s) 800. For example, if the
electrodepositable coating composition 900 is a cationic
electrodepositable coating composition, the substrate 1000 serves
as the cathode and the movable electrode 200 and, if present,
stationary electrode 800 serve as anodes, with the polarities
reversed for an anionic electrodepositable coating composition. The
power source provides an electric current to the electrocoating
system 10 such that the movable electrode 200 and, if present,
stationary electrode 800, provide an electric charge to the
electrodepositable coating composition 900 sufficient for
electrocoating purposes. Specifically, when the power source
provides an electrical current to the electrocoating system 10, the
electrodepositable coating composition 900 is charged by the
movable electrode 200 and, if present, the stationary electrode
800, and is attracted to, and deposits on, the oppositely-charged
substrate 1000. Equal, or substantially equal, charge distribution
throughout the electrically charged electrodepositable coating
composition 900 around the substrate 1000 provided by the
electrocoating system 10 of the present invention enhances the
electrocoating process by generally providing a substantially
uniform coating thickness of the electrodepositable coating
composition 900 deposited onto the entire surface of the substrate
1000. For example, but not by way of limitation, the electric
current provided to the power source may be, but is not limited to,
about 25 volts to about 600 volts or higher. The electrocoating
system 10 may also comprise any additional or other electrical
circuitry desired or needed to perform the purposes stated
herein.
[0049] As mentioned above, the electrocoating system 10 optionally
may further comprise at least one stationary electrode 800
positioned inside the tank 100 to provide additional electric
charge to the electrodepositable coating composition 900. The
stationary electrode 800 may comprise any suitable conductive
material known in the art. For example, the stationary electrode
800 may comprise a conductive pipe section electrically coupled
with the power source. The stationary electrode(s) 800 may be
membrane-free, or substantially membrane-free, or substantially
covered by a membrane. The electrocoating system 10 may comprise a
plurality of stationary electrodes 800, and the stationary
electrodes 800 may be positioned along a length of the tank 100
such that the electrodepositable coating composition 900 is
deposited substantially uniform along the length of the substrate
1000 to be electrocoated. For example, the stationary electrodes
800 may be positioned equidistant along a length of the tank 100.
The electrocoating system 10 may be configured such that the ratio
of a total combined surface area of the stationary electrode(s) 800
to the surface area of the second surface 1020 of the substrate
1000 may be from 1:7 to 1:1, such as 1:6 to 1:2, such as 1:5 to
1:3, such as 1:4.
[0050] Without intending to be bound by any theory, it is believed
that the use of a stationary electrode 800 alone in an
electrocoating system will not provide a sufficient charge to the
electrodepositable coating composition 900 to enable a uniform
deposition of the electrodepositable coating composition 900 over
the entire surface of the substrate 1000 without the movable
electrode 200 also being present. For example, the stationary
electrode 800 may provide a sufficient charge to the
electrodepositable coating composition 900 to deposit a coating on
a surface of the substrate 1000 located near the stationary
electrode 800, such as, for example, the second surface 1020 of the
substrate 1000, but may not provide a sufficient charge to enable
deposition of a continuous coating on other portions of the
substrate, such as, for example, the first surface 1010 of the
substrate 1000. The electrocoating system 10 of the present
invention may allow for substantial or complete coverage of the
first surface 1010 of the substrate 1000, for example, the
electrocoating system may result in at least 70% of the total
surface area of the first surface 1010 of the substrate 1000 to be
coated with a coating deposited from the electrodepositable coating
composition 900, such as at least 75%, such as at least 80%, such
as at least 85%, such as at least 90%, such as at least 95%, such
as at least 97%, such as at least 99%, such as 100%.
[0051] According to the present invention, the electrocoating
system 10 may be free of an ion exchange membrane, such as an ion
exchange membrane having an electrocatalyst applied onto a surface
thereof.
[0052] The electrodepositable coating composition 900 may comprise
any electrodepositable coating composition known in the art. As
used herein, the term "electrodepositable coating composition"
refers to a composition that is capable of being deposited onto an
electrically conductive substrate under the influence of an applied
electrical potential. For example, as mentioned above, the
electrodepositable coating composition 900 may comprise a cationic
or anionic electrodepositable coating composition.
[0053] The electrodepositable coating composition typically
comprises a film-forming binder. The film-forming binder may
comprise an ionic salt group-containing film-forming polymer and,
optionally, a curing agent.
[0054] According to the present invention, the ionic salt
group-containing film-forming polymer may comprise a cationic salt
group-containing film-forming polymer. The cationic salt
group-containing film-forming polymer may be used in a cationic
electrodepositable coating composition. As used herein, the term
"cationic salt group-containing film-forming polymer" refers to
polymers that include at least partially neutralized cationic
groups, such as sulfonium groups and/or ammonium groups, that
impart a positive charge to the polymer. As used herein, the term
"polymer" encompasses, but is not limited to, oligomers and both
homopolymers and copolymers. The cationic salt group-containing
film-forming polymer may comprise active hydrogen functional
groups. As used herein, the term "active hydrogen functional
groups" refers to those groups that are reactive with isocyanates
as determined by the Zerewitinoff test described in the JOURNAL OF
THE AMERICAN CHEMICAL SOCIETY, Vol. 49, page 3181 (1927), and
include, for example, hydroxyl groups, primary or secondary amino
groups, and thiol groups. Cationic salt group-containing
film-forming polymers that comprise active hydrogen functional
groups may be referred to as active hydrogen-containing, cationic
salt group-containing film-forming polymers.
[0055] Examples of polymers that are suitable for use as the
cationic salt group-containing film-forming polymer in the present
invention include, but are not limited to, alkyd polymers, acrylic
polymers, polyepoxide polymers, polyamide polymers, polyurethane
polymers, polyurea polymers, polyether polymers, and polyester
polymers, among others.
[0056] The cationic salt groups may be incorporated into the
cationic salt group-containing film-forming polymer as follows: The
film-forming polymer may be reacted with a cationic salt group
former. By "cationic salt group former" is meant a material which
is reactive with epoxy groups present and which may be acidified
before, during, or after reaction with the epoxy groups on the
film-forming polymer to form cationic salt groups. Examples of
suitable materials include amines such as primary or secondary
amines which can be acidified after reaction with the epoxy groups
to form amine salt groups, or tertiary amines which can be
acidified prior to reaction with the epoxy groups and which after
reaction with the epoxy groups form quaternary ammonium salt
groups. Examples of other cationic salt group formers are sulfides
which can be mixed with acid prior to reaction with the epoxy
groups and form ternary sulfonium salt groups upon subsequent
reaction with the epoxy groups.
[0057] More specific examples of suitable active
hydrogen-containing, cationic salt group containing film-forming
polymers include polyepoxide-amine adducts, such as the adduct of a
polyglycidyl ether of a polyphenol, such as Bisphenol A, and
primary and/or secondary amines, such as are described in U.S. Pat.
No. 4,031,050 at col. 3, line 27 to col. 5, line 50, U.S. Pat. No.
4,452,963 at col. 5, line 58 to col. 6, line 66, and U.S. Pat. No.
6,017,432 at col. 2, line 66 to col. 6, line 26, these portions of
which being incorporated herein by reference. A portion of the
amine that is reacted with the polyepoxide may be a ketimine of a
polyamine, as is described in U.S. Pat. No. 4,104,147 at col. 6,
line 23 to col. 7, line 23, the cited portion of which being
incorporated herein by reference. Also suitable are ungelled
polyepoxide-polyoxyalkylenepolyamine resins, such as are described
in U.S. Pat. No. 4,432,850 at col. 2, line 60 to col. 5, line 58,
the cited portion of which being incorporated herein by reference.
In addition, cationic acrylic resins, such as those described in
U.S. Pat. No. 3,455,806 at col. 2, line 18 to col. 3, line 61 and
U.S. Pat. No. 3,928,157 at col. 2, line 29 to col. 3, line 21,
these portions of both of which are incorporated herein by
reference, may be used.
[0058] Besides amine salt group-containing resins, the cationic
salt group-containing film-forming polymer may comprise a
quaternary ammonium salt group-containing resin. As used herein, a
"quaternary ammonium salt group" refers to a group comprising a
quaternary ammonium cation of the formula NR.sub.4.sup.+, wherein
each R group is independently an alkyl or aryl group, and a counter
anion. Examples of these resins are those which are formed from
reacting an organic polyepoxide with a tertiary amine acid salt.
Such resins are described in U.S. Pat. No. 3,962,165 at col. 2,
line 3 to col. 11, line 7; 3,975,346 at col. 1, line 62 to col. 17,
line 25 and U.S. Pat. No. 4,001,156 at col. 1, line 37 to col. 16,
line 7, these portions of which being incorporated herein by
reference.
[0059] Examples of other suitable cationic resins include ternary
sulfonium salt group-containing resins, such as those described in
U.S. Pat. No. 3,793,278 at col. 1, line 32 to col. 5, line 20, this
portion of which being incorporated herein by reference. Also,
cationic resins which cure via a transesterification mechanism,
such as described in European Patent Application No. 12463B1 at pg.
2, line 1 to pg. 6, line 25, this portion of which being
incorporated herein by reference, may also be employed.
[0060] Other suitable cationic salt group-containing film-forming
polymers include those that may form photodegradation resistant
electrodepositable coating compositions. Such polymers include the
polymers comprising cationic amine salt groups which are derived
from pendant and/or terminal amino groups that are disclosed in
U.S. Pat. Application Publication No. 2003/0054193 A1 at paragraphs
[0064] to [0088], this portion of which being incorporated herein
by reference. Also suitable are the active hydrogen-containing,
cationic salt group-containing resins derived from a polyglycidyl
ether of a polyhydric phenol that is essentially free of aliphatic
carbon atoms to which are bonded more than one aromatic group,
which are described in U.S. Pat. Application Publication No.
2003/0054193 A1 at paragraphs [0096] to [0123], this portion of
which being incorporated herein by reference.
[0061] The active hydrogen-containing, cationic salt
group-containing film-forming polymer may be made cationic and
water dispersible by at least partial neutralization with an acid.
Suitable acids include organic and inorganic acids. Non-limiting
examples of suitable organic acids include formic acid, acetic
acid, methanesulfonic acid, and lactic acid. Non-limiting examples
of suitable inorganic acids include phosphoric acid and sulfamic
acid. By "sulfamic acid" is meant sulfamic acid itself or
derivatives thereof such as those having the formula:
##STR00001##
wherein R is hydrogen or an alkyl group having 1 to 4 carbon atoms.
Mixtures of the above-mentioned acids also may be used in the
present invention.
[0062] The extent of neutralization of the cationic salt
group-containing film-forming polymer may vary with the particular
polymer involved. However, sufficient acid should be used to
sufficiently neutralize the cationic salt-group containing
film-forming polymer such that the cationic salt group-containing
film-forming polymer may be dispersed in an aqueous dispersing
medium. For example, the amount of acid used may provide at least
20% of all of the total theoretical neutralization. Excess acid may
also be used beyond the amount required for 100% total theoretical
neutralization. For example, the amount of acid used to neutralize
the cationic salt group-containing film-forming polymer may be
.gtoreq.0.1% based on the total amines in the active
hydrogen-containing, cationic salt group-containing film-forming
polymer. Alternatively, the amount of acid used to neutralize the
active hydrogen-containing, cationic salt group-containing
film-forming polymer may be .ltoreq.100% based on the total amines
in the active hydrogen-containing, cationic salt group-containing
film-forming polymer. The total amount of acid used to neutralize
the cationic salt group-containing film-forming polymer may range
between any combination of values, which were recited in the
preceding sentences, inclusive of the recited values. For example,
the total amount of acid used to neutralize the active
hydrogen-containing, cationic salt group-containing film-forming
polymer may be from about 20% to about 80%, such as 20%, 35%, 50%,
60%, or 80% based on the total amines in the cationic salt
group-containing film-forming polymer.
[0063] The cationic salt group-containing film-forming polymer may
be present in the cationic electrodepositable coating composition
in an amount of at least 40% by weight, such as at least 50% by
weight, such as at least 60% by weight, and may be present in an
amount of no more than 90% by weight, such as no more than 80% by
weight, such as no more than 75% by weight, based on the total
weight of the resin solids of the electrodepositable coating
composition. The cationic salt group-containing film-forming
polymer may for example be present in the cationic
electrodepositable coating composition in an amount of 40% to 90%
by weight, such as 50% to 80% by weight, such as 60% to 75% by
weight, based on the total weight of the resin solids of the
electrodepositable coating composition. As used herein, the "resin
solids" include the ionic salt group-containing film-forming
polymer, the curing agent (if present), and any additional
water-dispersible non-pigmented resinous component(s) present in
the electrodepositable coating composition.
[0064] According to the present invention, the ionic salt
group-containing film-forming polymer may comprise an anionic salt
group-containing film-forming polymer. As used herein, the term
"anionic salt group-containing film-forming polymer" refers to an
anionic polymer comprising at least partially neutralized anionic
functional groups, such as carboxylic acid and phosphoric acid
groups that impart a negative charge. The anionic salt
group-containing film-forming polymer may comprise active hydrogen
functional groups. Anionic salt group-containing film-forming
polymers that comprise active hydrogen functional groups may be
referred to as active hydrogen-containing, anionic salt
group-containing film-forming polymers. The anionic salt
group-containing film-forming polymer may be used in an anionic
electrodepositable coating composition.
[0065] The anionic salt group-containing film-forming polymer may
comprise base-solubilized, carboxylic acid group-containing
film-forming polymers such as the reaction product or adduct of a
drying oil or semi-drying fatty acid ester with a dicarboxylic acid
or anhydride; and the reaction product of a fatty acid ester,
unsaturated acid or anhydride and any additional unsaturated
modifying materials which are further reacted with a polyol. Also
suitable are the at least partially neutralized interpolymers of
hydroxy-alkyl esters of unsaturated carboxylic acids, unsaturated
carboxylic acid and at least one other ethylenically unsaturated
monomer. Still another suitable anionic electrodepositable resin
comprises an alkyd-aminoplast vehicle, i.e., a vehicle containing
an alkyd resin and an amine-aldehyde resin. Another suitable
anionic electrodepositable resin composition comprises mixed esters
of a resinous polyol. Other acid functional polymers may also be
used such as phosphatized polyepoxide or phosphatized acrylic
polymers. Exemplary phosphatized polyepoxides are disclosed in U.S.
Pat. Application Publication No. 2009-0045071 at [0004]-[0015] and
U.S. patent application Ser. No. 13/232,093 at [0014]-[0040], the
cited portions of which being incorporated herein by reference.
Also suitable are resins comprising one or more pendent carbamate
functional groups, such as those described in U.S. Pat. No.
6,165,338.
[0066] According to the present invention, the anionic salt
group-containing film-forming polymer may be present in the anionic
electrodepositable coating composition in an amount of at least 50%
by weight, such as at least 55% by weight, such as at least 60% by
weight, and may be present in an amount of no more than 90% by
weight, such as no more than 80% by weight, such as no more than
75% by weight, based on the total weight of the resin solids of the
electrodepositable coating composition. The anionic salt
group-containing film-forming polymer may be present in the anionic
electrodepositable coating composition in an amount of 50% to 90%,
such as 55% to 80%, such as 60% to 75%, based on the total weight
of the resin solids of the electrodepositable coating
composition.
[0067] According to the present invention, the electrodepositable
coating composition of the present invention may further comprise a
curing agent. The curing agent may be reactive with the ionic salt
group-containing film-forming polymer. The curing agent comprises
functional groups that react with the reactive functional groups,
such as active hydrogen groups, of the ionic salt group-containing
film-forming polymer to effectuate cure of the coating composition
to form a coating. As used herein, the term "cure", "cured" or
similar terms, as used in connection with the electrodepositable
coating compositions described herein, means that at least a
portion of the components that form the electrodepositable coating
composition are crosslinked to form a coating. Additionally, curing
of the electrodepositable coating composition refers to subjecting
said composition to curing conditions (e.g., elevated temperature)
leading to the reaction of the reactive functional groups of the
components of the electrodepositable coating composition, and
resulting in the crosslinking of the components of the composition
and formation of an at least partially cured coating. Non-limiting
examples of suitable curing agents are at least partially blocked
polyisocyanates, aminoplast resins and phenoplast resins, such as
phenolformaldehyde condensates including allyl ether derivatives
thereof.
[0068] Suitable at least partially blocked polyisocyanates include
aliphatic polyisocyanates, aromatic polyisocyanates, and mixtures
thereof. The curing agent may comprise an at least partially
blocked aliphatic polyisocyanate. Suitable at least partially
blocked aliphatic polyisocyanates include, for example, fully
blocked aliphatic polyisocyanates, such as those described in U.S.
Pat. No. 3,984,299 at col. 1 line 57 to col. 3 line 15, this
portion of which is incorporated herein by reference, or partially
blocked aliphatic polyisocyanates that are reacted with the polymer
backbone, such as is described in U.S. Pat. No. 3,947,338 at col. 2
line 65 to col. 4 line 30, this portion of which is also
incorporated herein by reference. By "blocked" is meant that the
isocyanate groups have been reacted with a compound such that the
resultant blocked isocyanate group is stable to active hydrogens at
ambient temperature but reactive with active hydrogens in the
film-forming polymer at elevated temperatures, such as between
90.degree. C. and 200.degree. C. The polyisocyanate curing agent
may be a fully blocked polyisocyanate with substantially no free
isocyanate groups.
[0069] The polyisocyanate curing agent may comprise a diisocyanate,
higher functional polyisocyanates or combinations thereof. For
example, the polyisocyanate curing agent may comprise aliphatic
and/or aromatic polyisocyanates. Aliphatic polyisocyanates may
include (i) alkylene isocyanates, such as trimethylene
diisocyanate, tetramethylene diisocyanate, pentamethylene
diisocyanate, hexamethylene diisocyanate ("HDI"), 1,2-propylene
diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate,
1,3-butylene diisocyanate, ethylidene diisocyanate, and butylidene
diisocyanate, and (ii) cycloalkylene isocyanates, such as
1,3-cyclopentane diisocyanate, 1,4-cyclohexane diisocyanate,
1,2-cyclohexane diisocyanate, isophorone diisocyanate, methylene
bis(4-cyclohexylisocyanate) ("HMDI"), the cyclo-trimer of
1,6-hexamethylene diisocyanate (also known as the isocyanurate
trimer of HDI, commercially available as Desmodur N3300 from
Convestro AG), and meta-tetramethylxylylene diisocyanate
(commercially available as TMXDI.RTM. from Allnex SA). Aromatic
polyisocyanates may include (i) arylene isocyanates, such as
m-phenylene diisocyanate, p-phenylene diisocyanate, 1,5-naphthalene
diisocyanate and 1,4-naphthalene diisocyanate, and (ii) alkarylene
isocyanates, such as 4,4'-diphenylene methane ("MDI"), 2,4-tolylene
or 2,6-tolylene diisocyanate ("TDI"), or mixtures thereof,
4,4-toluidine diisocyanate and xylylene diisocyanate.
Triisocyanates, such as triphenyl methane-4,4',4''-triisocyanate,
1,3,5-triisocyanato benzene and 2,4,6-triisocyanato toluene,
tetraisocyanates, such as 4,4'-diphenyldimethyl
methane-2,2',5,5'-tetraisocyanate, and polymerized polyisocyanates,
such as tolylene diisocyanate dimers and trimers and the like, may
also be used. The curing agent may comprise a blocked
polyisocyanate selected from a polymeric polyisocyanate, such as
polymeric HDI, polymeric MDI, polymeric isophorone diisocyanate,
and the like. The curing agent may also comprise a blocked trimer
of hexamethylene diisocyanate available as Desmodur N3300.RTM. from
Covestro AG. Mixtures of polyisocyanate curing agents may also be
used.
[0070] The polyisocyanate curing agent may be at least partially
blocked with at least one blocking agent selected from a 1,2-alkane
diol, for example 1,2-propanediol; a 1,3-alkane diol, for example
1,3-butanediol; a benzylic alcohol, for example, benzyl alcohol; an
allylic alcohol, for example, allyl alcohol; caprolactam; a
dialkylamine, for example dibutylamine; and mixtures thereof. The
polyisocyanate curing agent may be at least partially blocked with
at least one 1,2-alkane diol having three or more carbon atoms, for
example 1,2-butanediol.
[0071] Other suitable blocking agents include aliphatic,
cycloaliphatic, or aromatic alkyl monoalcohols or phenolic
compounds, including, for example, lower (e.g., C.sub.1-C.sub.6)
aliphatic alcohols, such as methanol, ethanol, and n-butanol;
cycloaliphatic alcohols, such as cyclohexanol; aromatic-alkyl
alcohols, such as phenyl carbinol and methylphenyl carbinol; and
phenolic compounds, such as phenol itself and substituted phenols
wherein the substituents do not affect coating operations, such as
cresol and nitrophenol. Glycol ethers and glycol amines may also be
used as blocking agents. Suitable glycol ethers include ethylene
glycol butyl ether, diethylene glycol butyl ether, ethylene glycol
methyl ether and propylene glycol methyl ether. Other suitable
blocking agents include oximes, such as methyl ethyl ketoxime,
acetone oxime and cyclohexanone oxime.
[0072] The curing agent may comprise an aminoplast resin.
Aminoplast resins are condensation products of an aldehyde with an
amino- or amido-group carrying substance. Condensation products
obtained from the reaction of alcohols and an aldehyde with
melamine, urea or benzoguanamine may be used. However, condensation
products of other amines and amides may also be employed, for
example, aldehyde condensates of triazines, diazines, triazoles,
guanidines, guanamines and alkyl- and aryl-substituted derivatives
of such compounds, including alkyl- and aryl-substituted ureas and
alkyl- and aryl-substituted melamines. Some examples of such
compounds are N,N'-dimethyl urea, benzourea, dicyandiamide,
formaguanamine, acetoguanamine, ammeline,
2-chloro-4,6-diamino-1,3,5-triazine,
6-methyl-2,4-diamino-1,3,5-triazine, 3,5-diaminotriazole,
triaminopyrimidine, 2-mercapto-4,6-diaminopyrimidine,
3,4,6-tris(ethylamino)-1,3,5-triazine, and the like. Suitable
aldehydes include formaldehyde, acetaldehyde, crotonaldehyde,
acrolein, benzaldehyde, furfural, glyoxal and the like.
[0073] The aminoplast resins may contain methylol or similar
alkylol groups, and at least a portion of these alkylol groups may
be etherified by a reaction with an alcohol to provide organic
solvent-soluble resins. Any monohydric alcohol may be employed for
this purpose, including such alcohols as methanol, ethanol,
propanol, butanol, pentanol, hexanol, heptanol and others, as well
as benzyl alcohol and other aromatic alcohols, cyclic alcohol such
as cyclohexanol, monoethers of glycols such as Cello-solves and
Carbitols, and halogen-substituted or other substituted alcohols,
such as 3-chloropropanol and butoxyethanol.
[0074] Non-limiting examples of commercially available aminoplast
resins are those available under the trademark CYMEL.RTM. from
Allnex Belgium SA/NV, such as CYMEL 1130 and 1156, and
RESIMENE.RTM. from INEOS Melamines, such as RESIMENE 750 and 753.
Examples of suitable aminoplast resins also include those described
in U.S. Pat. No. 3,937,679 at col. 16, line 3 to col. 17, line 47,
this portion of which being hereby incorporated by reference. As is
disclosed in the aforementioned portion of the '679 patent, the
aminoplast may be used in combination with the methylol phenol
ethers.
[0075] Phenoplast resins are formed by the condensation of an
aldehyde and a phenol. Suitable aldehydes include formaldehyde and
acetaldehyde. Methylene-releasing and aldehyde-releasing agents,
such as paraformaldehyde and hexamethylene tetramine, may also be
utilized as the aldehyde agent. Various phenols may be used, such
as phenol itself, a cresol, or a substituted phenol in which a
hydrocarbon radical having either a straight chain, a branched
chain or a cyclic structure is substituted for a hydrogen at the
aromatic ring. Mixtures of phenols may also be employed. Some
specific examples of suitable phenols are p-phenylphenol,
p-tert-butylphenol, p-tert-amylphenol, cyclopentylphenol and
unsaturated hydrocarbon-substituted phenols, such as the
monobutenyl phenols containing a butenyl group in ortho, meta or
para position, and where the double bond occurs in various
positions in the hydrocarbon chain.
[0076] Aminoplast and phenoplast resins, as described above, are
further described in U.S. Pat. No. 4,812,215 at col. 6, line 20 to
col. 7, line 12, the cited portion of which being incorporated
herein by reference.
[0077] The curing agent may be present in the cationic
electrodepositable coating composition in an amount of at least 10%
by weight, such as at least 20% by weight, such as at least 25% by
weight and may be present in an amount of no more than 60% by
weight, such as no more than 50% by weight, such as no more than
40% by weight, based on the total weight of the resin solids of the
electrodepositable coating composition. The curing agent may be
present in the cationic electrodepositable coating composition in
an amount of 10% to 60% by weight, such as 20% to 50% by weight,
such as 25% to 40% by weight, based on the total weight of the
resin solids of the electrodepositable coating composition.
[0078] The curing agent may be present in the anionic
electrodepositable coating composition in an amount of at least 10%
by weight, such as at least 20% by weight, such as at least 25% by
weight, and may be present in an amount of no more than 50% by
weight, such as no more than 45% by weight, such as no more than
40% by weight, based on the total weight of the resin solids of the
electrodepositable coating composition. The curing agent may be
present in the anionic electrodepositable coating composition in an
amount of 10% to 50% by weight, such as 20% to 45% by weight, such
as 25% to 40% by weight, based on the total weight of the resin
solids of the electrodepositable coating composition.
[0079] The electrodepositable coating composition according to the
present invention may optionally comprise one or more further
components in addition to the film-forming binder and curing agent
described above.
[0080] According to the present invention, the electrodepositable
coating composition may optionally comprise a catalyst to catalyze
the reaction between the curing agent and the polymers. Examples of
catalysts suitable for cationic electrodepositable coating
compositions include, without limitation, organotin compounds
(e.g., dibutyltin oxide and dioctyltin oxide) and salts thereof
(e.g., dibutyltin diacetate); other metal oxides (e.g., oxides of
cerium, zirconium and bismuth) and salts thereof (e.g., bismuth
sulfamate and bismuth lactate); or a cyclic guanidine as described
in U.S. Pat. No. 7,842,762 at col. 1, line 53 to col. 4, line 18
and col. 16, line 62 to col. 19, line 8, the cited portions of
which being incorporated herein by reference. Examples of catalysts
suitable for anionic electrodepositable coating compositions
include latent acid catalysts, specific examples of which are
identified in WO 2007/118024 at paragraph [0031] and include, but
are not limited to, ammonium hexafluoroantimonate, quaternary salts
of SbF.sub.6 (e.g., NACURE.RTM. XC-7231), t-amine salts of
SbF.sub.6 (e.g., NACURE.RTM. XC-9223), Zn salts of triflic acid
(e.g., NACURE.RTM. A202 and A218), quaternary salts of triflic acid
(e.g., NACURE.RTM. XC-A230), and diethylamine salts of triflic acid
(e.g., NACURE.RTM. A233), all commercially available from King
Industries, and/or mixtures thereof. Latent acid catalysts may be
formed by preparing a derivative of an acid catalyst such as
para-toluenesulfonic acid (pTSA) or other sulfonic acids. For
example, a well-known group of blocked acid catalysts are amine
salts of aromatic sulfonic acids, such as pyridinium
para-toluenesulfonate. Such sulfonate salts are less active than
the free acid in promoting crosslinking. During cure, the catalysts
may be activated by heating.
[0081] According to the present invention, the electrodepositable
coating composition may further comprise other optional
ingredients, such as a pigment composition and/or various additives
including fillers, plasticizers, anti-oxidants, biocides, UV light
absorbers and stabilizers, hindered amine light stabilizers,
defoamers, fungicides, dispersing aids, flow control agents,
surfactants, wetting agents, pH adjusters, buffering agents, or
combinations thereof. Alternatively, the electrodepositable coating
composition may be completely free of any of the optional
ingredients, i.e., the optional ingredient is not present in the
electrodepositable coating composition. The pigment composition may
comprise, for example, iron oxides, lead oxides, strontium
chromate, coal dust, titanium dioxide, talc, barium sulfate, as
well as color pigments such as cadmium yellow, cadmium red,
chromium yellow and the like. The pigment content of the pigment
composition, which excludes the electrically conductive particles
described above, may be expressed as the pigment-to-binder weight
ratio, and may be within the range of 0.03 to 0.1, when pigment is
used. The other additives mentioned above may be present in the
electrodepositable coating composition in amounts of 0.01% to 3% by
weight, based on total weight of the resin solids of the
electrodepositable coating composition.
[0082] According to the present invention, the electrodepositable
coating composition typically comprises an aqueous dispersion
medium comprising water and/or one or more organic solvent(s).
Water can for example be present in amounts of 40% to 90% by
weight, such as 50% to 80% by weight, such as 60% to 75% by weight,
based on total weight of the electrodepositable coating
composition. Examples of suitable organic solvents include
oxygenated organic solvents, such as monoalkyl ethers of ethylene
glycol, diethylene glycol, propylene glycol, and dipropylene glycol
which contain from 1 to 10 carbon atoms in the alkyl group, such as
the monoethyl and monobutyl ethers of these glycols. Examples of
other at least partially water-miscible solvents include alcohols
such as ethanol, isopropanol, butanol and diacetone alcohol. If
used, the organic solvents may typically be present in an amount of
less than 10% by weight, such as less than 5% by weight, based on
total weight of the electrodepositable coating composition. The
electrodepositable coating composition may in particular be
provided in the form of a dispersion, such as an aqueous
dispersion.
[0083] According to the present invention, the total solids content
of the electrodepositable coating composition may be at least 1% by
weight, such as at least 10% by weight, such as at least 20% by
weight, and may be no more than 60% by weight, such as no more than
40% by weight, such as no more than 20% by weight, based on the
total weight of the electrodepositable coating composition. The
total solids content of the electrodepositable coating composition
may be from 1% to 60% by weight, such as 10% to 40% by weight, such
as 20% to 30% by weight, based on the total weight of the
electrodepositable coating composition.
Method for Coating a Substrate and Coated Substrates
[0084] The present invention is also directed to a method for
coating a substrate comprising electrophoretically applying an
electrodepositable coating composition 900 to at least a portion of
the substrate 1000 using the electrocoating system 10 described
above. The method may comprise positioning the substrate 1000
within the tank 100 wherein a surface of the substrate 1000 to be
coated is at least partially submerged in the electrodepositable
coating composition 900; positioning a movable electrode 200;
electrically coupling the movable electrode 200 and the substrate
1000 to opposite poles of a power source; and then applying an
electrical current to the electrocoating system 10 from the power
source to electrodeposit the electrodepositable coating composition
900 onto the surface of the substrate 1000. For example, the
substrate 1000 may be electrically coupled to the positive or
negative terminal such that the substrate 1000 functions as a
cathode or anode, respectively, during electrocoating, and the
movable electrode 200 (and stationary electrode 800 if present) is
connected to the opposite pole to serve as a counter-electrode to
the substrate 1000. Once the movable electrode 200 is in position,
the external surface of the movable electrode 200 may be at a
distance of less than or equal to four feet from the surface of the
substrate 1000 to be coated.
[0085] The substrate 1000 used in the method of the present
invention may comprise a cavity. As discussed above, the substrate
1000 may comprise an open-polygon, polygon, or rounded
cross-sectional shape having at least one open end and a cavity.
For example, the substrate 1000 may be in the form of a container
or a pipe having at least one open end and an internal cavity. In
the method of the present invention, the movable electrode 200 may
be positioned or expanded such that the movable electrode 200
enters the cavity of the substrate 1000. As mentioned above, the
external surface of the movable electrode 200 may be at a distance
of less than or equal to four feet from the surface of the
substrate 1000 to be coated, such as less than or equal to 3.5
feet, such as less than or equal to 3 feet, such as less than or
equal to 2.5 feet, such as less than or equal to 2 feet, such as
less than or equal to 1.5 feet, such as less than or equal to 1
foot, such as less than or equal to 0.5 foot.
[0086] Following submersion of at least a portion of the substrate
1000 in the electrodepositable coating composition 900, an adherent
film of the electrodepositable coating composition 900 is deposited
on the substrate when a sufficient voltage is impressed between the
electrodes (i.e., the substrate 1000 and the movable electrode(s)
200 and, if present, stationary electrode(s) 800) by the power
source. The applied voltage may be varied and can be, for example,
as low as one volt to as high as several thousand volts, such as
between 25 and 600 volts. The current density may be between 0.5
ampere and 15 amperes per square foot.
[0087] The electrodepositable coating composition that may be used
in the method of the present invention may comprise any of those
known in the art, including those described above. For example, the
electrodepositable coating composition may comprise a cationic
film-forming resin comprising sulphonium groups and/or ammonium
groups, or the electrodepositable coating composition may comprise
an anionic electrodepositable coating composition comprising an
anionic film-forming resin comprising carboxylic acid and/or
phosphoric acid groups.
[0088] According to the present invention, the method may further
comprise at least partially curing the electrophoretically applied
electrodepositable coating composition on the substrate. As
discussed above, at least partially curing the electrodepositable
coating composition may comprise subjecting the substrate to
elevated temperatures. With respect to cationic electrodepositable
coating compositions, the coated substrate may be heated to a
temperature ranging from, for example, 250.degree. F. to
450.degree. F. (121.1.degree. C. to 232.2.degree. C.), such as from
275.degree. F. to 400.degree. F. (135.degree. C. to 204.4.degree.
C.), such as from 300.degree. F. to 360.degree. F. (149.degree. C.
to 180.degree. C.). With respect to anionic electrodepositable
coating compositions, the coated substrate may be heated to a
temperature ranging from, for example, 200.degree. F. to
450.degree. F. (93.degree. C. to 232.2.degree. C.), such as from
275.degree. F. to 400.degree. F. (135.degree. C. to 204.4.degree.
C.), such as from 300.degree. F. to 360.degree. F. (149.degree. C.
to 180.degree. C.). The curing time may be dependent upon the
curing temperature as well as other variables, for example, the
film thickness of the electrodeposited coating, level and type of
catalyst present in the composition, type of curing agent employed,
and the like. For purposes of the present invention, all that is
necessary is that the time be sufficient to effect cure of the
coating on the substrate. For example, the curing time can range
from 10 minutes to 60 minutes, such as 20 to 40 minutes. For
example, the thickness of the resultant cured electrodeposited
coating may range from 1 to 50 microns, such as 15 to 50
microns.
[0089] According to the present invention, the method for coating a
substrate may comprise (a) electrophoretically depositing onto at
least a portion of the substrate 1000 an electrodepositable coating
composition 900 using the electrocoating system 10 of the present
invention and (b) heating the coated substrate to a temperature and
for a time sufficient to at least partially cure the
electrodeposited coating composition 900 on the substrate.
According to the present invention, the method may optionally
further comprise (c) applying directly to the at least partially
cured electrodeposited coating one or more pigment-containing
coating compositions and/or one or more pigment-free coating
compositions to form an additional coating layer over at least a
portion of the at least partially cured electrodeposited coating,
and (d) curing the additional coating layer by allowing it to set
at ambient temperature or by applying a sufficient energy from an
external energy source to the coated substrate of step (c) to a
condition and for a time sufficient to at least partially cure the
additional coating layer. Non-limiting examples of external energy
sources include thermal energy and radiation such as ultraviolet,
infrared or microwave.
[0090] The optional additional coating layer may comprise one or
more primer layer(s) and suitable topcoat layer(s) (e.g., base
coat, clearcoat layer, pigmented monocoat, and color-plus-clear
composite compositions). It is understood that suitable additional
coating layers include any of those known in the art, and each
independently may be waterborne, solventborne, in solid particulate
form (i.e., a powder coating composition), or in the form of a
powder slurry. The additional coating compositions may comprise a
film-forming polymer, crosslinking material and, if a colored base
coat or monocoat, one or more pigments. The primer layer(s) may
optionally be disposed between the electrocoating layer and the
topcoat layer(s). Alternatively, the topcoat layer(s) may be
omitted such that the composite comprises the electrocoating layer
and one or more primer layer(s).
[0091] Moreover, the topcoat layer(s) may be applied directly onto
the electrodepositable coating layer. In other words, the substrate
may lack a primer layer such that the composite comprises the
electrocoating layer and one or more topcoat layer(s). For example,
a basecoat layer may be applied directly onto at least a portion of
the electrodepositable coating layer.
[0092] It will also be understood that any of the topcoat layers
may be applied onto an underlying layer despite the fact that the
underlying layer has not been fully cured. For example, a clearcoat
layer may be applied onto a basecoat layer even though the basecoat
layer has not been subjected to a curing step (wet-on-wet). Both
layers may then be cured during a subsequent curing step thereby
eliminating the need to cure the basecoat layer and the clearcoat
layer separately.
[0093] According to the present invention, additional ingredients
such as colorants and fillers may be present in the various coating
compositions from which the top coat layers result. Any suitable
colorants and fillers may be used, such as those described above.
For example, the colorant may be added to the coating in any
suitable form, such as discrete particles, dispersions, solutions
and/or flakes. A single colorant or a mixture of two or more
colorants can be used in the coatings of the present invention. It
should be noted that, in general, the colorant can be present in a
layer of the multi-layer composite in any amount sufficient to
impart the desired property, visual and/or color effect.
[0094] Example colorants include pigments, dyes and tints, such as
those used in the paint industry and/or listed in the Dry Color
Manufacturers Association (DCMA), as well as special effect
compositions. A colorant may include, for example, a finely divided
solid powder that is insoluble but wettable under the conditions of
use. A colorant may be organic or inorganic and may be agglomerated
or non-agglomerated. Colorants may be incorporated into the
coatings by grinding or simple mixing. Colorants may be
incorporated by grinding into the coating by use of a grind
vehicle, such as an acrylic grind vehicle, the use of which will be
familiar to one skilled in the art.
[0095] Example pigments and/or pigment compositions include, but
are not limited to, carbazole dioxazine crude pigment, azo,
monoazo, disazo, naphthol AS, salt type (lakes), benzimidazolone,
condensation, metal complex, isoindolinone, isoindoline and
polycyclic phthalocyanine, quinacridone, perylene, perinone,
diketopyrrolo pyrrole, thioindigo, anthraquinone, indanthrone,
anthrapyrimidine, flavanthrone, pyranthrone, anthanthrone,
dioxazine, triarylcarbonium, quinophthalone pigments, diketo
pyrrolo pyrrole red ("DPP red BO"), titanium dioxide, carbon black,
zinc oxide, antimony oxide, etc. and organic or inorganic UV
opacifying pigments such as iron oxide, transparent red or yellow
iron oxide, phthalocyanine blue and mixtures thereof. The terms
"pigment" and "colored filler" can be used interchangeably.
[0096] Example dyes include, but are not limited to, those that are
solvent and/or aqueous based such as acid dyes, azoic dyes, basic
dyes, direct dyes, disperse dyes, reactive dyes, solvent dyes,
sulfur dyes, mordant dyes, for example, bismuth vanadate,
anthraquinone, perylene, aluminum, quinacridone, thiazole,
thiazine, azo, indigoid, nitro, nitroso, oxazine, phthalocyanine,
quinoline, stilbene, and triphenyl methane.
[0097] Example tints include, but are not limited to, pigments
dispersed in water-based or water-miscible carriers such as
AQUA-CHEM 896 commercially available from Degussa, Inc., CHARISMA
COLORANTS and MAXITONER INDUSTRIAL COLORANTS commercially available
from Accurate Dispersions division of Eastman Chemical, Inc.
[0098] The colorant may be in the form of a dispersion including,
but not limited to, a nanoparticle dispersion. Nanoparticle
dispersions can include one or more highly dispersed nanoparticle
colorants and/or colorant particles that produce a desired visible
color and/or opacity and/or visual effect. Nanoparticle dispersions
may include colorants such as pigments or dyes having a particle
size of less than 150 nm, such as less than 70 nm, or less than 30
nm. Nanoparticles may be produced by milling stock organic or
inorganic pigments with grinding media having a particle size of
less than 0.5 mm. Example nanoparticle dispersions and methods for
making them are identified in U.S. Pat. No. 6,875,800 B2, which is
incorporated herein by reference. Nanoparticle dispersions may also
be produced by crystallization, precipitation, gas phase
condensation, and chemical attrition (i.e., partial dissolution).
In order to minimize re-agglomeration of nanoparticles within the
coating, a dispersion of resin-coated nanoparticles may be used. As
used herein, a "dispersion of resin-coated nanoparticles" refers to
a continuous phase in which is dispersed discreet "composite
microparticles" that comprise a nanoparticle and a resin coating on
the nanoparticle. Example dispersions of resin-coated nanoparticles
and methods for making them are identified in U.S. patent
application Ser. No. 10/876,031 filed Jun. 24, 2004, which is
incorporated herein by reference, and U.S. Provisional Pat.
Application Ser. No. 60/482,167 filed Jun. 24, 2003, which is also
incorporated herein by reference.
[0099] According to the present invention, special effect
compositions that may be used in one or more layers of the
multi-layer coating composite include pigments and/or compositions
that produce one or more appearance effects such as reflectance,
pearlescence, metallic sheen, phosphorescence, fluorescence,
photochromism, photosensitivity, thermochromism, goniochromism
and/or color-change. Additional special effect compositions may
provide other perceptible properties, such as reflectivity, opacity
or texture. For example, special effect compositions may produce a
color shift, such that the color of the coating changes when the
coating is viewed at different angles. Example color effect
compositions are identified in U.S. Pat. No. 6,894,086,
incorporated herein by reference. Additional color effect
compositions may include transparent coated mica and/or synthetic
mica, coated silica, coated alumina, a transparent liquid crystal
pigment, a liquid crystal coating, and/or any composition wherein
interference results from a refractive index differential within
the material and not because of the refractive index differential
between the surface of the material and the air.
[0100] According to the present invention, a photosensitive
composition and/or photochromic composition, which reversibly
alters its color when exposed to one or more light sources, can be
used in a number of layers in the multi-layer composite.
Photochromic and/or photosensitive compositions can be activated by
exposure to radiation of a specified wavelength. When the
composition becomes excited, the molecular structure is changed and
the altered structure exhibits a new color that is different from
the original color of the composition. When the exposure to
radiation is removed, the photochromic and/or photosensitive
composition can return to a state of rest, in which the original
color of the composition returns. For example, the photochromic
and/or photosensitive composition may be colorless in a non-excited
state and exhibit a color in an excited state. Full color-change
may appear within milliseconds to several minutes, such as from 20
seconds to 60 seconds. Example photochromic and/or photosensitive
compositions include photochromic dyes.
[0101] The photosensitive composition and/or photochromic
composition may be associated with and/or at least partially bound
to, such as by covalent bonding, a polymer and/or polymeric
materials of a polymerizable component. In contrast to some
coatings in which the photosensitive composition may migrate out of
the coating and crystallize into the substrate, the photosensitive
composition and/or photochromic composition associated with and/or
at least partially bound to a polymer and/or polymerizable
component in accordance with the present invention has minimal
migration out of the coating. Example photosensitive compositions
and/or photochromic compositions and methods for making them are
identified in U.S. patent application Ser. No. 10/892,919 filed
Jul. 16, 2004 and incorporated herein by reference.
[0102] The additional coating layers may be applied by a topcoat
system. The topcoat system may comprise any equipment and/or method
known in the art to apply a topcoat coating composition. For
example, the topcoat system may comprise equipment to apply a
powder coating composition or a liquid coating composition. For
example, the topcoat system may comprise a spray gun, a brush, a
roller, a tank for immersion coating, or combinations thereof. The
topcoat system may optionally further comprise a spraybooth, and
the spraybooth may optionally comprise a ventilation system.
[0103] As mentioned above, the coating composition may be a powder
coating composition. As used herein, "powder coating composition"
refers to a coating composition which is completely free of water
and/or solvent. Accordingly, the powder coating composition
disclosed herein is not synonymous to waterborne and/or
solventborne coating compositions known in the art.
[0104] According to the present invention, the powder coating
composition comprises (a) a film-forming polymer having a reactive
functional group; and (b) a curing agent that is reactive with the
functional group. Examples of powder coating compositions that may
be used in the present invention include the polyester-based
ENVIROCRON line of powder coating compositions (commercially
available from PPG Industries, Inc.) or epoxy-polyester hybrid
powder coating compositions. Alternative examples of powder coating
compositions that may be used in the present invention include low
temperature cure thermosetting powder coating compositions
comprising (a) at least one tertiary aminourea compound, at least
one tertiary aminourethane compound, or mixtures thereof, and (b)
at least one film-forming epoxy-containing resin and/or at least
one siloxane-containing resin (such as those described in U.S. Pat.
No. 7,470,752, assigned to PPG Industries Ohio, Inc. and
incorporated herein by reference); curable powder coating
compositions generally comprising (a) at least one tertiary
aminourea compound, at least one tertiary aminourethane compound,
or mixtures thereof, and (b) at least one film-forming
epoxy-containing resin and/or at least one siloxane-containing
resin (such as those described in U.S. Pat. No. 7,432,333, assigned
to PPG Industries Ohio, Inc. and incorporated herein by reference);
and those comprising a solid particulate mixture of a reactive
group-containing polymer having a T.sub.g of at least 30.degree. C.
(such as those described in U.S. Pat. No. 6,797,387, assigned to
PPG Industries Ohio Inc. and incorporated herein by reference).
[0105] Suitable film-forming polymers that may be used in the
powder coating composition of the present invention comprise a
(poly)ester (e.g., polyester triglycidyl isocyanurate), a
(poly)urethane, an isocyanurate, a (poly)urea, a (poly)epoxy, an
anhydride, an acrylic, a (poly)ether, a (poly)sulfide, a
(poly)amine, a (poly)amide, (poly)vinyl chloride, (poly)olefin,
(poly)vinylidene fluoride, or combinations thereof.
[0106] According to the present invention, the reactive functional
group of the film-forming polymer of the powder coating composition
comprises hydroxyl, carboxyl, isocyanate (including blocked
(poly)isocyanate), primary amine, secondary amine, amide,
carbamate, urea, urethane, vinyl, unsaturated ester, maleimide,
fumarate, anhydride, hydroxyl alkylamide, epoxy, or combinations
thereof.
[0107] Suitable curing agents (crosslinking agents) that may be
used in the powder coating composition of present invention
comprise an aminoplast resin, a polyisocyanate, a blocked
polyisocyanate, a polyepoxide, a polyacid, a polyol, or
combinations thereof.
[0108] After deposition of the powder coating composition, the
coating is often heated to cure the deposited composition. The
heating or curing operation is often carried out at a temperature
in the range of from 150.degree. C. to 200.degree. C., such as from
170.degree. C. to 190.degree. C., for a period of time ranging from
10 to 20 minutes. According to the invention, the thickness of the
resultant film is from 50 microns to 125 microns.
[0109] As mentioned above, the coating composition may be a liquid
coating composition. As used herein, "liquid coating composition"
refers to a coating composition which contains a portion of water
and/or solvent. Accordingly, the liquid coating composition
disclosed herein is synonymous to waterborne and/or solventborne
coating compositions known in the art.
[0110] According to the present invention, the liquid coating
composition may comprise, for example, (a) a film-forming polymer
having a reactive functional group; and (b) a curing agent that is
reactive with the functional group. In other examples, the liquid
coating may contain a film-forming polymer that may react with
oxygen in the air or coalesce into a film with the evaporation of
water and/or solvents. These film-forming mechanisms may require or
be accelerated by the application of heat or some type of radiation
such as ultraviolet or infrared. Examples of liquid coating
compositions that may be used in the present invention include the
SPECTRACRON.RTM. line of solvent-based coating compositions, the
AQUACRON.RTM. line of water-based coating compositions, and the
RAYCRON.RTM. line of UV cured coatings (all commercially available
from PPG Industries, Inc.).
[0111] Suitable film-forming polymers that may be used in the
liquid coating composition of the present invention may comprise a
(poly)ester, an alkyd, a (poly)urethane, an isocyanurate, a
(poly)urea, a (poly)epoxy, an anhydride, an acrylic, a (poly)ether,
a (poly)sulfide, a (poly)amine, a (poly)amide, (poly)vinyl
chloride, (poly)olefin, (poly)vinylidene fluoride, (poly)siloxane,
or combinations thereof.
[0112] According to the present invention, the reactive functional
group of the film-forming polymer of the liquid coating composition
may comprise hydroxyl, carboxyl, isocyanate (including blocked
(poly)isocyanate), primary amine, secondary amine, amide,
carbamate, urea, urethane, vinyl, unsaturated ester, maleimide,
fumarate, anhydride, hydroxyl alkylamide, epoxy, or combinations
thereof.
[0113] Suitable curing agents (crosslinking agents) that may be
used in the liquid coating composition of the present invention may
comprise an aminoplast resin, a polyisocyanate, a blocked
polyisocyanate, a polyepoxide, a polyacid, a polyol, or
combinations thereof.
[0114] In addition, a colorant and, if desired, various additives
such as surfactants, wetting agents or catalyst can be included in
the coating composition (electrodepositable, powder, or liquid). As
used herein, the term "colorant" means any substance that imparts
color and/or other opacity and/or other visual effect to the
composition. The colorant can be added to the composition in any
suitable form, such as discrete particles, dispersions, solutions
and/or flakes. A single colorant or a mixture of two or more
colorants can be used.
[0115] Example colorants include pigments, dyes and tints, such as
those used in the paint industry and/or listed in the Dry Color
Manufacturers Association (DCMA), as well as special effect
compositions. A colorant may include, for example, a finely divided
solid powder that is insoluble but wettable under the conditions of
use. A colorant can be organic or inorganic and can be agglomerated
or non-agglomerated. Colorants can be incorporated by use of a
grind vehicle, such as an acrylic grind vehicle, the use of which
will be familiar to one skilled in the art.
[0116] Example pigments and/or pigment compositions include, but
are not limited to, carbazole dioxazine crude pigment, azo,
monoazo, disazo, naphthol AS, salt type (lakes), benzimidazolone,
condensation, metal complex, isoindolinone, isoindoline and
polycyclic phthalocyanine, quinacridone, perylene, perinone,
diketopyrrolo pyrrole, thioindigo, anthraquinone, indanthrone,
anthrapyrimidine, flavanthrone, pyranthrone, anthanthrone,
dioxazine, triarylcarbonium, quinophthalone pigments, diketo
pyrrolo pyrrole red ("DPPBO red"), titanium dioxide, carbon black
and mixtures thereof. The terms "pigment" and "colored filler" can
be used interchangeably.
[0117] Example dyes include, but are not limited to, those that are
solvent and/or aqueous based such as phthalo green or blue, iron
oxide, bismuth vanadate, anthraquinone, perylene, aluminum and
quinacridone.
[0118] Example tints include, but are not limited to, pigments
dispersed in water-based or water-miscible carriers such as
AQUA-CHEM 896 commercially available from Degussa, Inc., CHARISMA
COLORANTS and MAXITONER INDUSTRIAL COLORANTS commercially available
from Accurate Dispersions division of Eastman Chemical, Inc.
[0119] As noted above, the colorant can be in the form of a
dispersion including, but not limited to, a nanoparticle
dispersion. Nanoparticle dispersions can include one or more highly
dispersed nanoparticle colorants and/or colorant particles that
produce a desired visible color and/or opacity and/or visual
effect. Nanoparticle dispersions can include colorants such as
pigments or dyes having a particle size of less than 150 nm, such
as less than 70 nm, or less than 30 nm. Nanoparticles can be
produced by milling stock organic or inorganic pigments with
grinding media having a particle size of less than 0.5 mm. Example
nanoparticle dispersions and methods for making them are identified
in U.S. Pat. No. 6,875,800 B2, which is incorporated herein by
reference. Nanoparticle dispersions can also be produced by
crystallization, precipitation, gas phase condensation, and
chemical attrition (i.e., partial dissolution). In order to
minimize re-agglomeration of nanoparticles within the coating, a
dispersion of resin-coated nanoparticles can be used. As used
herein, a "dispersion of resin-coated nanoparticles" refers to a
continuous phase in which is dispersed discreet "composite
microparticles" that comprise a nanoparticle and a resin coating on
the nanoparticle. Example dispersions of resin-coated nanoparticles
and methods for making them are identified in U.S. Pat. Application
Publication No. 2005-0287348 A1, filed Jun. 24, 2004, U.S.
Provisional Pat. Application No. 60/482,167 filed Jun. 24, 2003,
and U.S. patent application Ser. No. 11/337,062, filed Jan. 20,
2006, which is also incorporated herein by reference.
[0120] Example special effect compositions that may be used include
pigments and/or compositions that produce one or more appearance
effects such as reflectance, pearlescence, metallic sheen,
phosphorescence, fluorescence, photochromism, photosensitivity,
thermochromism, goniochromism and/or color-change. Additional
special effect compositions can provide other perceptible
properties, such as opacity or texture. According to the invention,
special effect compositions can produce a color shift, such that
the color of the coating changes when the coating is viewed at
different angles. Example color effect compositions are identified
in U.S. Pat. No. 6,894,086, incorporated herein by reference.
Additional color effect compositions can include transparent coated
mica and/or synthetic mica, coated silica, coated alumina, a
transparent liquid crystal pigment, a liquid crystal coating,
and/or any composition wherein interference results from a
refractive index differential within the material and not because
of the refractive index differential between the surface of the
material and the air.
[0121] According to the invention, a photosensitive composition
and/or photochromic composition, which reversibly alters its color
when exposed to one or more light sources, can be used.
Photochromic and/or photosensitive compositions can be activated by
exposure to radiation of a specified wavelength. When the
composition becomes excited, the molecular structure is changed and
the altered structure exhibits a new color that is different from
the original color of the composition. When the exposure to
radiation is removed, the photochromic and/or photosensitive
composition can return to a state of rest, in which the original
color of the composition returns. According to the invention, the
photochromic and/or photosensitive composition can be colorless in
a non-excited state and exhibit a color in an excited state. Full
color-change can appear within milliseconds to several minutes,
such as from 20 seconds to 60 seconds. Example photochromic and/or
photosensitive compositions include photochromic dyes.
[0122] The photosensitive composition and/or photochromic
composition can be associated with and/or at least partially bound
to, such as by covalent bonding, a polymer and/or polymeric
materials of a polymerizable component. In contrast to some
coatings in which the photosensitive composition may migrate out of
the coating and crystallize into the substrate, the photosensitive
composition and/or photochromic composition associated with and/or
at least partially bound to a polymer and/or polymerizable
component have minimal migration out of the coating. Example
photosensitive compositions and/or photochromic compositions and
methods for making them are identified in U.S. patent application
Ser. No. 10/892,919 filed Jul. 16, 2004, incorporated herein by
reference.
[0123] In general, the colorant can be present in the coating
composition in any amount sufficient to impart the desired visual
and/or color effect. The colorant may comprise from 1% to 65% by
weight, such as from 3% to 40% by weight or 5% to 35% by weight,
with weight percent based on the total weight of the
composition.
[0124] According to the present invention, the method may
optionally further comprise pretreating the substrate with a
pretreatment composition prior to applying the electrodepositable
coating composition using the electrocoating system. As used
herein, the term "pretreatment composition" refers to a composition
that is capable of reacting with and chemically altering the
substrate surface and binding to it to form a film that affords
corrosion protection. Non-limiting examples of a pretreatment
composition include zinc phosphate pretreatment compositions such
as, for example, those described in U.S. Pat. Nos. 4,793,867 and
5,588,989, zirconium containing pretreatment compositions such as,
for example, those described in U.S. Pat. Nos. 7,749,368 and
8,673,091, and the like. The pretreatment composition may be
brought into contact with the substrate by any of a variety of
known techniques, such as dipping or immersion, spraying,
intermittent spraying, dipping followed by spraying, spraying
followed by dipping, brushing, or roll-coating. According to the
invention, the pretreatment composition when applied to the
substrate may be at a temperature ranging from, for example,
40.degree. F. to 160.degree. F. (4.4.degree. C. to 71.1.degree.
C.), such as 60.degree. F. to 110.degree. F. (15.6.degree. C. to
43.3.degree. C.), such as 70.degree. F. to 90.degree. F.
(21.1.degree. C. to 32.2.degree. C.). For example, the pretreatment
process may be carried out at ambient or room temperature. The
contact time is often from 1 second to 15 minutes, such as 4
seconds to 10 minutes, such as 5 seconds to 4 minutes.
[0125] Following the contacting with the pretreatment composition,
the substrate optionally may be dried in place, e.g., air dried at
room temperature or be dried with hot air, for example, by using an
air knife, by flashing off the water by brief exposure of the
substrate to a high temperature, such as by drying the substrate in
an oven at 15.degree. C. to 100.degree. C., such as 20.degree. C.
to 90.degree. C., or in a heater assembly using, for example,
infrared heat, such as for 10 minutes at 70.degree. C., or by
passing the substrate between squeegee rolls. The substrate surface
may be partially, or in some instances, completely dried prior to
any subsequent contact of the substrate surface with any water,
solutions, compositions, or the like. According to the present
invention, following the contacting with the pretreatment
composition, the substrate (either wet or dried) optionally may be
rinsed with tap water, deionized water, and/or an aqueous solution
of rinsing agents in order to remove any residue and then
optionally may be dried, for example air dried or dried with hot
air as described in the preceding sentence. According to the
present invention, such water rinses may be eliminated and the
substrate (either wet or dried in place) may be contacted with
subsequent treatment compositions.
[0126] The pretreatment composition may be applied to the substrate
by a pretreatment system. The pretreatment system may comprise
tanks for immersion, brushes, rollers, spray guns, or combinations
thereof to apply the pretreatment composition to the substrate. The
pretreatment system may further comprise tanks, brushes, rollers,
spray guns, or combinations thereof for applying rinse
compositions, such as water, to the substrate after it is contacted
with the pretreatment composition.
[0127] According to the present invention, the method may
optionally further comprise priming the substrate with a priming
composition prior to applying the electrodepositable coating
composition using the electrocoating system. The priming
composition may be used alone or in combination with the
pretreatment composition or other treatments prior to applying the
electrodepositable coating composition. The priming composition may
comprise a metal-rich coating composition. As used herein, the term
"metal-rich coating composition" refers to film-forming
compositions that include an organic or inorganic binder and at
least 65% by weight metal particles, based on the total solids
weight of the coating composition. As used herein, the term "metal
particles" refers to elemental (i.e., zerovalent) metal and metal
alloy particles. As used herein, the term "particles" refers to
material in the form of particulates, such as powder or dust, as
well as flakes, and may be in the form of any shape, such as, for
example, spherical, ellipsoidal, cubical, rod-shaped, disk-shaped,
prism-shaped, and the like. The metal may comprise zinc, aluminum,
or alloys thereof. The priming composition may be brought into
contact with the substrate by any of a variety of known techniques,
such as dipping or immersion, spraying, electrostatic spraying,
intermittent spraying, dipping followed by spraying, spraying
followed by dipping, brushing, or roll-coating. It is appreciated
that the metal-rich primer coatings can also be applied in dry
forms such as powder or films. The metal-rich primer coatings
formed from the priming composition can be applied to a dry film
thickness of, for example, 2.5 to 500 microns.
[0128] After application of the priming composition to the
substrate, a film formed on the surface of the substrate may be
dried by driving solvent out of the film by heating or by an
air-drying period. Suitable drying conditions will depend on the
particular priming composition and/or application, but an exemplary
drying time of from about 1 to 5 minutes at a temperature of about
60 to 250.degree. F. (15.6 to 121.degree. C.), such as 70 to
212.degree. F. (27 to 100.degree. C.) may be sufficient. More than
one primer coating layer may be applied if desired. Between coats,
the previously applied coat may be flashed; that is, exposed to
ambient conditions for a desired amount of time.
[0129] After application of the priming composition to a substrate,
the applied priming composition may be cured by any means known in
the art. For example, the coating may be subjected to curing
conditions sufficient to cure the priming composition. For example,
the coating composition may be subjected to curing conditions such
as ambient conditions, as discussed above, for a period of hours or
days. Alternatively, the substrate may be subjected to curing
conditions such as radiation (e.g., UV radiation) or heated to a
temperature and for a time sufficient to cure the priming
coating.
[0130] The priming composition may be applied to the substrate by a
priming system. The priming system may comprise tanks for
immersion, brushes, rollers, spray guns, or combinations thereof to
apply the priming composition to the substrate. The priming system
may further comprise tanks, brushes, rollers, spray guns, or
combinations thereof for applying rinse compositions, such as
water, to the substrate.
[0131] According to the present invention, the substrate may
optionally be subjected to other treatments prior to
electrocoating. For example, the substrate may be rinsed, cleaned,
deoxidized, cleaned and deoxidized, anodized, acid pickled, plasma
treated, laser treated, or ion vapor deposition (IVD) treated. At
least a portion of the surface of the substrate may be cleaned by
physical and/or chemical means, such as mechanically abrading the
surface and/or cleaning/degreasing the surface with commercially
available alkaline or acidic cleaning agents that are well known to
those skilled in the art. These optional treatments may be used on
their own or in combination with a pretreatment composition and/or
a priming composition.
[0132] The present invention is also directed towards a substrate
coated using the electrocoating system described above. The
substrate may optionally be further coated using the topcoat
system. Accordingly, the substrate comprises an electrocoating
layer and an optional topcoat layer.
[0133] The present invention is also directed towards a substrate
coated using the pretreatment system and electrocoating system,
both as described above. The substrate may optionally be coated
using the topcoat system. Accordingly, the substrate may comprise a
pretreatment layer, an electrocoating layer and an optional topcoat
layer.
[0134] The present invention is also directed towards a substrate
coated using the priming system and electrocoating system, both as
described above. The substrate may optionally be coated using the
topcoat system. Accordingly, the substrate may comprise a priming
layer, an electrocoating layer and an optional topcoat layer.
[0135] The present invention is also directed towards a substrate
coated using the pretreatment system, priming system and
electrocoating system, each as described above. The substrate may
optionally be coated using the topcoat system. Accordingly, the
substrate comprises a pretreatment layer, a priming layer, an
electrocoating layer and an optional topcoat layer.
[0136] The present invention is also directed towards a substrate
coated according to the method of the present invention.
System for Coating a Substrate
[0137] The present invention is also directed towards a system for
coating a substrate comprising the electrocoating system as
described above. The system for coating a substrate may optionally
further comprise the pretreatment system, the priming system, the
topcoat system, or any combination thereof. For example, the system
for coating a substrate may comprise the pretreatment system for
pretreating the substrate; the priming system for priming the
substrate; the electrocoating system for electrocoating the
substrate; and the topcoat system for applying a topcoat coating to
the substrate. The system for coating a substrate may comprise any
combination of the systems discussed above applied sequentially.
For example, the system for coating a substrate may comprise the
pretreatment system followed by the electrocoat system; the system
for coating a substrate may comprise the pretreatment system
followed by the electrocoat system followed by the topcoat system;
the system for coating a substrate may comprise the priming system
followed by the electrocoat system; the system for coating a
substrate may comprise the priming system followed by the
electrocoat system followed by the topcoat system; the system for
coating a substrate may comprise the pretreatment system followed
by the priming system followed by the electrocoat system; the
system for coating a substrate may comprise the pretreatment system
followed by the priming system followed by the electrocoat system
followed by the topcoat system; or the system for coating a
substrate may comprise the electrocoat system followed by the
topcoat system.
[0138] In view of the foregoing, the present invention thus relates
inter alia, without being limited thereto, to the following
aspects: A first aspect is directed to an electrocoating system
comprising: a tank comprising at least one sidewall and configured
to hold an electrodepositable coating composition for receiving a
substrate to be coated, and a movable electrode positioned within
the tank, wherein the movable electrode does not extend through the
sidewall. A second aspect is directed to the electrocoating system
according to the first aspect, further comprising at least one
means for positioning the movable electrode within the tank. A
second aspect is directed to the electrocoating system of the
second aspect, wherein the means for positioning the movable
electrode within the tank comprises an apparatus positioned above
the tank, the apparatus having an arm configured to position the
expandable electrode within the tank. A fourth aspect is directed
to the electrocoating system of the third aspect, wherein the
apparatus comprises a cart positioned on at least one rail and is
laterally moveable on the rail relative to the tank. A fifth aspect
is directed to the electrocoating system according to any of the
preceding aspects, wherein the movable electrode comprises an
expandable electrode. A sixth aspect is directed to the
electrocoating system of the fifth aspect, wherein the expandable
electrode is positioned on the sidewall and is configured to expand
away from the sidewall. A seventh aspect is directed to the
electrocoating system of the fifth aspect, wherein the tank further
comprises a floor and the expandable electrode is positioned on the
floor, wherein the expandable electrode is configured to expand
away from the floor and does not extend through the floor of the
tank. An eighth aspect is directed to the electrocoating system of
any one of the fifth through seventh aspects, further comprising at
least one means for positioning, means for expanding and/or means
for retracting the expandable electrode within the tank. A ninth
aspect is directed to the electrocoating system according to any
one of the fifth through eighth aspects, wherein the means for
positioning, means for expanding and/or means for retracting the
expandable electrode within the tank comprise an apparatus
positioned above the tank, the apparatus having an arm configured
to position the expandable electrode within the tank. A tenth
aspect is directed to the electrocoating system of the ninth
aspect, wherein the apparatus comprises a cart, wherein the cart is
positioned on at least one rail and is laterally moveable on the
rail relative to the tank. An eleventh aspect is directed to the
electrocoating system of the tenth aspect, further comprising a
second cart comprising an arm connected to the expandable
electrode, wherein the first and second carts are configured to at
least partially expand the expandable electrode. A twelfth aspect
is directed to the electrocoating system of the eleventh aspect,
wherein the system further comprises a means for further expanding
the expandable electrode. A thirteenth aspect is directed to the
electrocoating system according to any one of the ninth through
twelfth aspects, wherein the means for expanding or means for
further expanding the expandable electrode comprises a driving
means, wherein the driving means comprises a rack and pinion, a
pneumatic press, a hydraulic press, or a combination thereof. A
fourteenth aspect is directed to the electrocoating system
according to any one of the preceding aspects, wherein the
expandable electrode comprises a telescoping electrode. A fifteenth
aspect is directed to the electrocoating system according to the
fourteenth aspect, wherein at least a portion of the telescoping
electrode is formed of telescoping sections that may be nested one
within another, wherein the telescoping electrode comprises n
telescoping sections each having a length of X, the telescoping
sections allow expanding the length of the telescoping electrode by
a length of up to nX-X, wherein n is an integer >1. A sixteenth
aspect is directed to the electrocoating system according to any
one of the fifth through eighth aspects, wherein the expandable
electrode comprises a flexible material comprising a rope or
hose-like configuration. A seventeenth aspect is directed to the
electrocoating system according to any one of the preceding
aspects, further comprising a means for counter-balancing the
expandable electrode in an expanded state. An eighteenth aspect is
directed to the electrocoating system according to any one of the
preceding aspects, further comprising at least one stationary
electrode and/or being free of an ion exchange membrane. A
nineteenth aspect is directed to the electrocoating system
according to any one of the fifth through eighteenth aspects,
wherein the expandable electrode further comprises a spacer. A
twentieth aspect is directed to the electrocoating system according
to any one of the preceding aspects, wherein the movable electrode
is at least one of: (1) located entirely within the tank, (2)
configured to be free of points of contact with the substrate to be
coated, (3) having a surface that is free of electrocatalyst, (4)
comprising a non-porous material, and/or (5) completely submerged
in the electrodepositable coating composition. A twenty-first
aspect is directed to the electrocoating system according to any
one of the preceding aspects, wherein the movable electrode is
connected to a terminal of a power supply and the substrate to be
coated is connected to a terminal of opposite polarity of the power
supply. A twenty-second aspect is directed to the electrocoating
system according to any one of the preceding aspects, further
comprising a means for tilting and/or rotating the substrate to be
coated. A twenty-third aspect is directed to the electrocoating
system according to any one of the preceding aspects, wherein the
movable electrode further comprises at least one protrusion. A
twenty-fourth aspect is directed to a method for coating a
substrate using the electrocoating system according to any one of
preceding aspects, the method comprising: positioning the substrate
within the tank wherein a surface of the substrate to be coated is
submerged in the electrodepositable coating composition held in the
tank; positioning the movable electrode; electrically coupling the
movable electrode and the substrate to opposite poles of a power
source; and then applying an electrical current from the power
source to electrodeposit a coating deposited from the
electrodepositable coating composition onto the surface of the
substrate. A twenty-fifth aspect is directed to the method
according to the twenty-fourth aspect, wherein the substrate
comprises a container having a cavity, and the movable electrode is
positioned into the cavity. A twenty-sixth aspect is directed to
the method according to any one of twenty-fourth or twenty-fifth
aspects, wherein the movable electrode has an external surface, and
the external surface is at a distance of less than or equal to four
feet from the surface of the substrate to be coated after the
positioning of the movable electrode. A twenty-seventh aspect is
directed to a method for coating a substrate using the
electrocoating system according to any one of the fifth through
twenty-third aspects, the method comprising: positioning the
substrate within the tank wherein a surface of the substrate to be
coated is submerged in the electrodepositable coating composition
held in the tank; expanding the expandable electrode; electrically
coupling the expandable electrode and the substrate to opposite
poles of a power source; and then applying an electrical current
from the power source to electrodeposit a coating deposited from
the electrodepositable coating composition onto the surface of the
substrate. A twenty-eighth aspect is directed to the method
according to the twenty-seventh aspect, wherein the substrate
comprises a container having a cavity, and the expandable electrode
is expanded into the cavity. A twenty-ninth aspect is directed to a
substrate coated by the method according to any one of the
twenty-fourth through twenty-eighth aspects. A thirtieth aspect is
directed to a system for coating a substrate comprising the
electrocoating system according to any one of the preceding first
through twenty-third aspects, and further comprising at least one
of (1) a pretreatment system for pretreating the substrate prior to
processing the substrate in the electrocoating system; (2) a
priming system for priming the substrate prior to processing the
substrate in the electrocoating system; and/or (3) a topcoat system
for applying a topcoat coating to the substrate after processing
the substrate in the electrocoating system.
[0139] For purposes of the detailed description, it is to be
understood that the invention may assume various alternative
variations and step sequences, except where expressly specified to
the contrary. Moreover, other than in any operating examples, or
where otherwise indicated, all numbers such as those expressing
values, amounts, percentages, ranges, subranges and fractions may
be read as if prefaced by the word "about", even if the term does
not expressly appear. Accordingly, unless indicated to the
contrary, the numerical parameters set forth in the following
specification and attached claims are approximations that may vary
depending upon the desired properties to be obtained by the present
invention. At the very least, and not as an attempt to limit the
application of the doctrine of equivalents to the scope of the
claims, each numerical parameter should at least be construed in
light of the number of reported significant digits and by applying
ordinary rounding techniques. Where a closed or open-ended
numerical range is described herein, all numbers, values, amounts,
percentages, subranges and fractions within or encompassed by the
numerical range are to be considered as being specifically included
in and belonging to the original disclosure of this application as
if these numbers, values, amounts, percentages, subranges and
fractions had been explicitly written out in their entirety.
[0140] Notwithstanding that the numerical ranges and parameters
setting forth the broad scope of the invention are approximations,
the numerical values set forth in the specific examples are
reported as precisely as possible. Any numerical value, however,
inherently contains certain errors necessarily resulting from the
standard variation found in their respective testing
measurements.
[0141] As used herein, unless indicated otherwise, a plural term
can encompass its singular counterpart and vice versa, unless
indicated otherwise. For example, although reference is made herein
to "a" movable electrode, "a" telescoping section, "a" means for
positioning the movable electrode within the tank, "an" arm, "a"
cart, "a" rail, "a" leg, "a" means for expanding the expandable
electrode, "a" means for retracting the expandable electrode, "a"
means for counterbalancing the movable electrode, and "a"
stationary electrode, a combination (i.e., a plurality) of these
components can be used. In addition, in this application, the use
of "or" means "and/or" unless specifically stated otherwise, even
though "and/or" may be explicitly used in certain instances.
[0142] As used herein, "including", "containing" and like terms are
understood in the context of this application to be synonymous with
"comprising" and are therefore open-ended and do not exclude the
presence of additional undescribed or unrecited elements,
materials, ingredients or method steps. As used herein, "consisting
of" is understood in the context of this application to exclude the
presence of any unspecified element, ingredient or method step. As
used herein, "consisting essentially of" is understood in the
context of this application to include the specified elements,
materials, ingredients or method steps "and those that do not
materially affect the basic and novel characteristic(s)" of what is
being described.
[0143] As used herein, the terms "on", "onto", "applied on",
"applied onto", "formed on", "deposited on", "deposited onto", mean
formed, overlaid, deposited, or provided on but not necessarily in
contact with the surface. For example, an electrodepositable
coating composition "deposited onto" a substrate does not preclude
the presence of one or more other intervening coating layers of the
same or different composition located between the
electrodepositable coating composition and the substrate.
[0144] Whereas specific embodiments of the invention have been
described in detail, it will be appreciated by those skilled in the
art that various modifications and alternatives to those details
could be developed in light of the overall teachings of the
disclosure. Accordingly, the particular arrangements disclosed are
meant to be illustrative only and not limiting as to the scope of
the invention which is to be given the full breadth of the claims
appended and any and all equivalents thereof.
[0145] It will be appreciated by skilled artisans that numerous
modifications and variations are possible in light of the above
disclosure without departing from the broad inventive concepts
described and exemplified herein. Accordingly, it is therefore to
be understood that the foregoing disclosure is merely illustrative
of various exemplary aspects of this application and that numerous
modifications and variations can be readily made by skilled
artisans which are within the spirit and scope of this application
and the accompanying claims.
* * * * *