U.S. patent application number 11/709483 was filed with the patent office on 2008-08-28 for electrocoated conductive fabric.
Invention is credited to Elizabeth Cates, Alfred R. DeAngelis.
Application Number | 20080202623 11/709483 |
Document ID | / |
Family ID | 39339783 |
Filed Date | 2008-08-28 |
United States Patent
Application |
20080202623 |
Kind Code |
A1 |
DeAngelis; Alfred R. ; et
al. |
August 28, 2008 |
Electrocoated conductive fabric
Abstract
The present invention generally relates to an insulated
electrically conductive textile comprising a textile selected from
the group consisting of nonwoven, woven, and knit comprising
nonconductive fibers or yarns and at least 1 elongated conductive
element and either another elongated conductive element or another
conductive body. The conductive bodies cross at a point to form an
electrical junction that is covered with an insulating coating. The
insulating coating is substantially located only on the conductive
bodies and is substantially continuous along the outer perimeter of
the elongated conductive elements.
Inventors: |
DeAngelis; Alfred R.;
(Spartanburg, SC) ; Cates; Elizabeth; (Duncan,
SC) |
Correspondence
Address: |
Legal Department (M-495)
P.O. Box 1926
Spartanburg
SC
29304
US
|
Family ID: |
39339783 |
Appl. No.: |
11/709483 |
Filed: |
February 22, 2007 |
Current U.S.
Class: |
139/425R ;
427/522 |
Current CPC
Class: |
D06N 3/0063 20130101;
D06N 2205/20 20130101; D06N 2209/041 20130101; D06N 2209/123
20130101; D06N 3/0086 20130101 |
Class at
Publication: |
139/425.R ;
427/522 |
International
Class: |
D03D 25/00 20060101
D03D025/00 |
Claims
1. An insulated electrically conductive textile comprising a
textile selected from the group consisting of nonwoven, woven, and
knit comprising nonconductive fibers or yarns and at least 2
conductive bodies having an electrically insulating coating that
cross at a point to form an electrical junction, wherein the
electrically insulating coating is substantially located only on
the conductive bodies, wherein the electrically insulating coating
covers at least 50% of the surface area of the conductive bodies
and greater than 99% of the surface area of the electrical
junction, and wherein the insulating coating on the conductive
bodies and the electrical junction are formed of the same
materials.
2. The insulated electrically conductive textile of claim 1,
wherein the conductive bodies comprise at least 2 elongated
conductive elements.
3. The insulated electrically conductive textile of claim 1,
wherein the conductive bodies comprise at least 1 elongated
conductive element and at least one electrically conductive
connector.
4. The insulated electrically conductive textile of claim 1,
wherein the insulating coating is formed on the conductive bodies
and the electrical junction simultaneously.
5. The insulated electrically conductive textile of claim 1,
wherein the conductive bodies comprise a metal selected from the
group consisting of stainless steel, nickel, aluminum, copper, tin,
silver, gold, and alloys thereof.
6. The insulated electrically conductive textile of claim 1,
wherein the conductive bodies comprise carbon.
7. The insulated electrically conductive textile of claim 1,
wherein the electrically insulating coating comprises a polymeric
material.
8. The insulated electrically conductive textile of claim 1,
wherein the conductive textile is flexible.
9. The insulated electrically conductive textile of claim 1,
wherein the electrically insulating coating covers at least 95% of
the surface area of the conductive bodies.
10. The insulated electrically conductive textile of claim 2,
wherein the electrically insulating coating is continuous between
the elongated conductive elements.
11. The insulated electrically conductive textile of claim 3,
wherein the electrically insulating coating is continuous between
the electrically conductive connector and the elongated conductive
element.
12. The insulated electrically conductive textile of claim 1,
wherein the nonconductive fibers comprise less than 10% by weight
insulating coating.
13. A process for producing an insulated electrically conductive
textile comprising: providing an solution comprising an ionizable
moiety; depositing a conductive textile selected from the group
consisting of nonwoven, woven, and knit comprising nonconductive
fibers or yarns and at least two conductive bodies forming an
electrical junction and a conductive electrode in contact with the
solution; applying an electric potential between the conductive
textile and the conductive electrode, causing the ionizable
moieties to deposit selectively on the elongated conductive bodies
of the textile forming an electrically insulating coating
substantially only on the conductive bodies, wherein the
electrically insulating coating covers at least 50% of the surface
area of the conductive bodies and greater than 99% of the surface
area of the electrical junction; removing the insulated conductive
textile from the solution; rinsing the insulated conductive
textile; and curing the insulated conductive textile.
14. The insulated electrically conductive textile of claim 13,
wherein the conductive bodies comprise at least 2 elongated
conductive elements.
15. The insulated electrically conductive textile of claim 13,
wherein the conductive bodies comprise at least 1 elongated
conductive element and at least one electrically conductive
connector.
16. The process of claim 13, further comprising cleaning and
rinsing the conductive textile before depositing the conductive
textile into the aqueous solution.
17. The process of claim 13, further comprising pretreating with an
acid bath and rinsing the conductive textile before depositing the
conductive textile into the aqueous solution.
18. The process of claim 13, wherein the conductive electrode
comprises graphite.
19. The process of claim 13, wherein the conductive textile serves
as the anode.
20. The process of claim 14, wherein the electrically insulating
coating is substantially continuous along the outer perimeter of
the elongated conductive elements.
21. The process of claim 13, wherein the nonconductive fibers
comprise less than 10% by weight insulating coating after the
textile is cured.
22. The insulated electrically conductive textile of claim 14,
wherein the electrically insulating coating is continuous between
the elongated conductive elements.
Description
TECHNICAL FIELD
[0001] The present invention generally relates to an insulated
electrically conductive fabric with insulated electrically
conductive bodies in the fabric while maintaining the electrical
connection between those elements and the process for making the
fabric.
BACKGROUND
[0002] Electrically conductive fabrics often need to be insulated,
both to protect the circuit from the environment or protect the
user from the circuit. Most conductive fabrics with insulation are
made by insulating the conductive materials before they are
incorporated into a fabric. For example, an insulated wire may be
woven into or stitched onto a fabric. This precludes easy or
automated electrical connections within the fabric.
[0003] Connections can be made more easily if the conductive
materials are not insulated when incorporated into the fabric. In
this case, insulating the conductive materials has meant the
application of a film or thick coating to the entire fabric, which
creates a stiff, impermeable product.
[0004] There is a need for an electrically conductive fabric that
is flexible, breathable (permeable to vapors or gases) that
insulates the electrical elements in the fabric while maintaining
the electrical connection between those elements.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] An embodiment of the present invention will now be described
by way of example, with reference to the accompanying drawings.
[0006] FIG. 1 is a schematic of a top view of one embodiment of the
insulated conductive fabric;
[0007] FIG. 2 is a schematic of a cut-away view of one embodiment
of the insulated conductive fabric;
[0008] FIG. 3 is a schematic of a side view of one embodiment of
the insulated conductive fabric;
[0009] FIG. 4 is a schematic of an insulated conductive
connector;
[0010] FIG. 5 is a schematic of a top view of one embodiment of the
conductive fabric before being insulated;
[0011] FIG. 6 is a schematic of an electrophoretic bath with the
conductive fabric;
[0012] FIG. 7 is a schematic of the electrophoretic process to form
an insulated conductive fabric;
[0013] FIG. 8 is a photograph on the top view of an insulated
conductive fabric; and,
[0014] FIG. 9 is a photograph on the cross-sectional view of an
insulated conductive fabric.
DETAILED DESCRIPTION
[0015] Referring to FIG. 1, there is shown a top view of one of the
embodiments of the insulated electrically conductive textile 10
comprising nonconductive yarns 100 and at least 2 insulated
conductive bodies which may be insulated elongated conductive
elements 201 and/or insulated electrically conductive connectors
202. In one embodiment, the textile 10 comprises at least 2
insulated elongated conductive elements 201 and in another
embodiment, the textile 10 comprises at least 1 insulated
electrically conductive connector 202 and at least 1 elongated
conductive element 201. The conductive bodies 201, 202 cross at
least one point in the textile 10 forming an electrical
junction.
[0016] FIG. 2 shows an illustrated cut-away view of the textile 10
and FIG. 3 shows an illustrated cross-section of the textile 10.
The insulated elongated conductive elements 201 shown contain an
elongated conductive element 210 surrounded by an insulating
coating 212. An elongated conductive element 210 means a single
independent unit of a continuous slender body having a high ratio
of length to cross-sectional distance, such as cords, wires, tapes,
threads, yarns, or the like. The elongated conductive element 210
can be a single component, or multiple components combined to form
the continuous elongated element. The electrical junction 110
between two insulated elongated conductive elements 201 may be seen
in FIG. 3 and as a cross-sectional photograph in FIG. 9.
[0017] Referring now to FIG. 4, one of the insulated conductive
bodies shown is an insulated conductive connector 202. The
insulated conductive connector 202 is formed from an electrically
conductive connector 211 with an insulting coating 213. Electrical
connectors can be any of a number of devices or materials designed
to connect two electrically conductive components in a
semi-permanent or permanent manner, including but not limited to
crimp connectors, insulation displacement connectors, wire lug
terminals, pin/socket terminals, clip connectors such as
"alligator" clips, snap connectors, rivets, and zippers such as
those used in apparel closures, and the like. Electrical connection
is guaranteed between the elongated conductive element and the
electrical connector by mechanically crimping, soldering, or
otherwise affixing with electrically conductive material such as
conductive paint, elastomer/rubber, epoxy, or glue the two
components together.
[0018] The elongated conductive elements 210 and conductive
connectors 211 may be formed from any conductive material. In one
embodiment the conductive bodies 210, 211 are formed from any metal
including copper, aluminum, nickel, carbonyl nickel, molybdenum,
silver, gold, zinc, cadmium, iron, tin, beryllium, lead, steel,
bronze, brass, and alloys of one or more of the foregoing metals.
In another embodiment, the conductive bodies 210, 211 comprise
carbon, such as carbon fiber, carbon filaments, or carbon-doped
polymers. In yet another embodiment, the conductive bodies 210, 211
are combinations of metal and polymers or yarns such as
silver-coated yarns or metal-doped polymers or certain conductive
polymers such as poly(aniline), poly(pyrrole), poly(thiophene),
poly(acetylene), poly(fluorene), poly(3-hexylthiophene),
poly(naphthalene), poly(p-phenylene sulfide), or
poly(para-phenylene vinylene). Additionally, the elongated
conductive elements 210 are of a material that is able to be formed
into an elongated element such as a wire or yarn.
[0019] The insulated elongated conductive elements 201 are
preferably flexible. Flexible, as used herein in association with
an insulated elongated element 201 or fabric 10, shall mean the
ability to bend around an axis perpendicular to the lengthwise
direction of the strand with light to moderate force while still
maintaining a working electrical connection. In one embodiment, the
flexible elongated element or fabric requires no more than about
1000 grams of force to be pressed through a 15 mm wide slot to a
depth 6 mm, such as performed by a Handle-O-Meter manufactured by
Thwing vAlbert Instrument Co., Philadelphia, Pa.
[0020] The insulated electrically conductive fabric 10 may be of
any stitch construction suitable to the end use, including by not
limited to woven, knitted, non-woven, and tufted textiles, or the
like. The conductivity of the insulated electrically conductive
fabric 10 will vary according to the end use. In one embodiment
where the insulated electrically conductive fabric 10 is used as a
heating garment, such as a glove, the surface resistance of the
insulated conductive fabric 10 may be approximately 0.01 to 100
ohms.
[0021] Woven textiles can include, but are not limited to, satin,
twill, basket-weave, poplin, and crepe weave textiles. Jacquard
woven structures may be useful for creating more complex electrical
patterns. Knit textiles can include, but are not limited to,
circular knit, reverse plaited circular knit, double knit, single
jersey knit, two-end fleece knit, three-end fleece knit, terry knit
or double loop knit, warp knit, and warp knit with or without a
microdenier face. The fabric 10 may be flat or may exhibit a
pile.
[0022] As used herein yarn shall mean a continuous strand of
textile fibers, spun or twisted textile fibers, textile filaments,
or material in a form suitable for knitting, weaving, or otherwise
intertwining to form a textile. The term yarn includes, but is not
limited to, yarns of monofilament fiber, multifilament fiber,
staple fibers, or a combination thereof. The nonconductive yarns
100 have a low conductivity such that any flow of electric current
through it is negligible. In one example, a non-conductive yarn
will have a resistivity of at least 1.times.10.sup.13
ohms/inch.
[0023] The non-conductive fibers or yarns 100 may be any natural or
man-made fibers including but not limited to man-made fibers such
as polyethylene, polypropylene, polyesters (polyethylene
terephthalate, polybutylene terephthalate, polytrimethylene
terephthalate, polylactic acid, and the like, including copolymers
thereof, nylons (including nylon 6 and nylon 6,6), regenerated
cellulosics (such as rayon or Tencel.TM.), elastomeric materials
such as Lycra.TM., high-performance fibers such as the polyaramids,
polyimides, PEI, PBO, PBI, PEEK, liquid-crystalline, thermosetting
polymers such as melamine-formaldehyde (Basofil.TM.) or
phenol-formaldehyde (Kynol.TM.), basalt, glass, ceramic, cotton,
coir, bast fibers, proteinaceous materials such as silk, wool,
other animal hairs such as angora, alpaca, or vicuna, and blends
thereof. Nonconductive yarns that are less porous are more
preferred as they absorb less of the electrophoretic bath chemistry
and solvent.
[0024] The insulating coatings 212, 213 on the insulated conductive
bodies 201, 202 are organic or inorganic polymers that are either
soluble or dispersible in the process solvent, most commonly water,
and possess ionizable moieties such that the polymers or polymer
dispersions can be forced to migrate in solution by application of
an electrical current. Suitable aqueous polymer dispersions
incorporate an ionizable functional group into the structure of the
polymer and/or may be stabilized by ionizable surfactants.
Preferred polymers undergo a change in solubility at the working
electrode, either by a change in the oxidation state of the polymer
itself, by reaction with the reduction or oxidation products of the
working electrode itself, by disruption of the stabilizing
surfactant dispersion, by exceeding the local solubility limit, or
by other means know in the art. More preferred polymers are those
that may be chemically cross-linked to form an insoluble durable
coating.
[0025] In one embodiment, the invention utilizes electrocoating to
selectively coat the conductive portions of a conductive fabric 1
shown in FIG. 5, while not depositing on the nonconductive fibers
or yarns 100. This forms the insulated conductive fabric 10 shown
in FIG. 1 with insulated conductive bodies 201, 202 while the
fabric 10 remains flexible, air permeable, and vapor permeable. It
also allows for further treatments of the nonconductive fibers and
yarns 100 for wicking, odor control, flame retardation, etc.
Electrocoating creates a very even, continuous coating on the
conductive elements, even in crevices and other partially occluded
areas that convention coatings traditionally miss or undercoat.
[0026] Electrocoating (e-coating) is a method of depositing
polymer-based paint or coatings onto conductive surfaces via
electrically-induced precipitation. E-coating is commonly used in
the automotive industry, for example. It involves using one
partially or fully conductive article as one electrode (working
electrode) (in our case the conductive fabric) and a second
conductive article (typically a graphite electrode) (counter
electrode) into an aqueous bath containing ionizable moieties and
passing a current between the two electrodes.
[0027] The organic or inorganic polymers, or organic or inorganic
compounds, collectively referred to as "ionizable moieties", are
deposited onto an electrically conductive substrate, typically
carbon or metallic. In the invention, the substrate may be formed
of individual fibers, or as a fabric of fibers. In either case, the
ionizable moieties deposit at and may or may not chemically bond to
the surfaces of the conductive bodies 210 and 211. For example,
polymers incorporating ionizable moieties in the structure of the
polymer may chemically bond to the electrode or may be
electrochemically transformed into a non-soluble species. Latexes
that are dispersed using ionic surfactants can be caused to
precipitate out at the electrode by disturbing the
surfactant-mediated dispersion, not chemical bonding to the
conductive body itself. The conditions for electrodeposition are
maintained until the desired thickness of deposition is
achieved.
[0028] The process is performed by immersing a conductive textile 1
in an electrolysis cell 500 containing a solution 501 (preferably
aqueous) with an organic compound or polymer, or inorganic compound
or polymer having ionizable moieties 400 as described above,
detailed in FIG. 6, and shown as step 650 in FIG. 7. The
electrophoretic process may be cationic or anionic (the process
being specified whether the conductive fabric serves as the cathode
or anode). In a cationic electrophoretic process, the working
electrode serves as the cathode at which reduction takes place that
is the cathode supplies electrons to the solution and attracts
cationic species in the solution. In an anionic electrophoretic
process, the polarity of the system is reversed, with the working
electrode acting as the positively charged anode that attracts
anionic species in the solution. With metal working electrodes, a
cationic process is preferred because the negative charge on the
working electrode effectively prevents electrolytic dissolution of
the metal working electrode. In anionic electrophoretic processes,
metal working electrodes may undergo oxidation to form soluble
metal cations in solution, which contaminate the bath and may cause
solution precipitation of the coating material. In one embodiment,
the electrodeposition is performed where the conductive textile 1
acts as the cathode, where the other electrode 510 in contact with
the solution of ionizable moieties acts as a anode, and where the
application of an electric potential causes the negatively
ionizable moiety in solution to migrate to the anode.
[0029] The insulating coating 212, 213 (formed from the ionizable
moieties) is simultaneously deposited on the conductive bodies 210,
211 and the electrical junctions, forming a continuous insulating
coating on the insulated conductive bodies 201, 202 and the
electrical junctions between them. The insulating coating 212, 213
on the insulated conductive bodies 201, 202 is of the same material
and chemical make up as the insulating coating on the electrical
junctions. The insulating coating covers greater than 99% of the
surface area of the electrical junctions between the conductive
bodies (elongated conductive elements 201 and electrically
conductive connectors 202). The insulating coating deposits
substantially only on the conductive elements in the conductive
textile. The portion of the insulating coating on the nonconductive
fibers or yarns 100 of the conductive textile comprise less than
10% by weight, more preferably 5% by weight, more preferably 2% by
weight, and more preferably 1%, of the insulating coating after the
electrophoretic process. In another embodiment, the amount of
insulating material added to the nonconductive elements is less
than 50%, more preferably less than 25%, more preferably less than
10%, of the amount of insulating material added to the conductive
elements. Preferably, the insulating coating is substantially
continuous along the outer perimeter of the insulated elongated
conductive elements 201 and the insulated electrically conductive
connectors 202. In another embodiment, the insulating coating
covers at least 95%, more preferably 99%, of the surface area of
the insulated elongated conductive elements 201 and the insulated
electrically conductive connectors 202.
[0030] Once the desired amount of insulating coating is deposited
onto the insulated conductive bodies 201 and 202 in the now
insulated conductive textile 10, the insulated conductive textile
10 is removed from the solution 660, rinsed 670, and cured 680. How
the insulated conductive textile 10 is cured in step 680 shown in
FIG. 7 depends on the materials of the conductive bodies 201 and
202, nonconductive yarns 100, and insulating coatings 212 and 213.
The curing may be at room temperature or at an elevated
temperature.
[0031] Additionally, before placing the conductive textile 1 into
the solution, there may be additional cleaning 610 and rinsing 620,
and/or pretreating with an acid bath 630 and rinsing 640 steps to
prepare the conductive bodies 210 and 211 for the electrophoretic
process.
[0032] The insulated electrically conductive textile 10 preferably
has an air permeability of greater than about 25 cfm at 125 Pa
using TexTest air permeability test equipment (ASTM D737). In one
embodiment, the air permeability of the insulated conductive fabric
10 is at least 90%, more preferably at least 96% of the air
permeability of the uncoated conductive fabric 1. This range of air
permeability has been shown to create textiles that may be used as
garments and other textile applications where the fabric needs to
"breathe". Prior art methods for insulating conductive elements in
a textile involving applying an insulting material to the entire
textile would not achieve this level of air permeability. In
another embodiment, the insulated electrically conductive textile
has a vapor permeability of greater than about 1000 g/m.sup.2/24
hours, in one embodiment with an upper limit of 15,000 g/m.sup.2/24
hours as measured by ASTM E 96-95. Having this range of vapor
permeability has also been shown to create textiles that may formed
into wearable and comfortable garments.
EXAMPLES
[0033] The example fabric was made starting with a coarse plain
weave fabric with a weight of heavy 6.25 oz/sq yd formed from
polyester filament yarns. The polyester yarns used in the warp
direction were 1134 denier at 22 ypi woven with 2 ends per
dent.
[0034] The polyester yarns used in the weft direction were 1148
denier with 18 ppi. Every 21/2 inches the fill yarn was replaced by
three consecutive conductive yarns. The first and third conductive
yarns were from IntraMicron of Alabama, consisting of 250 solid
copper filaments that were each 33 microns in diameter. The middle
conductive yarn was a silver-coated nylon 3-ply yarn, with two
monofilament yarns wrapped (S- and Z-) around a 24 filament core
yarn with a denier of 204.
[0035] Every 30 inches one pair of warp yarns was replaced by a
pair of the same copper yarns used in the weft. On either side of
the warp copper warp yarns were a pair of silver-coated nylon yarns
with 2-ply with 34 filaments in each singles yarn and a total
denier of 407.5, inserted as a leno weave. The conductive yarns
formed a connected electrical network.
[0036] Fabric samples (A) were prepared for electrocoating from the
aforesaid fabric construction by scouring according to standard
textile processing techniques known in the art. Samples were then
heat-set at 400.degree. F. for 5 minutes to stabilize the fabric
for further processing. A set of control fabric samples (B) was
made from greige fabric of the aforesaid construction. Sections of
fabric, approximately 16'' by 36'' were cut from the weft direction
of the fabric such that each section contained at least one set of
conductive yarns in the warp and the fabric edges were within 1''
of the nearest set of weft conductive yarns. The raw edges of the
fabric were turned and sewn to create a piece of fabric with
finished edges. The female half of uncoated rivet-style metal snaps
were inserted 8.5'' apart on center through the set of weft
conductive yarns nearest to the edge of the fabric. The metal snaps
served to connect the fabric with conductive yarns to a metal frame
(C) that would carry the fabric through the electrocoating process.
The metal frame had the corresponding male uncoated rivet-style
metal snaps affixed to it such that the fabric samples could be
snapped to it and held in place during the electrocoating
process.
[0037] The e-coating process had 12 tanks that samples were passed
through prior to the drying/curing ovens:
[0038] 1. caustic clean
[0039] 2. caustic clean
[0040] 3. water rinse
[0041] 4. conditioning rinse
[0042] 5. acid/zinc phosphate bath
[0043] 6. water rinse
[0044] 7. water rinse
[0045] 8. deionized water rinse
[0046] 9. e-coat bath
[0047] 10. water rinse
[0048] 11. water rinse
[0049] 12. water rinse
[0050] Experiment I: Fabric sample (A-1) was snapped to a metal
frame and loaded into the rack conveyor system of a commercial
electrocoating process as shown in FIG. 6. The coating system used
was an 800-series black cationic epoxy from PPG Industries of
Pittsburgh, Pa., typically used for automotive and other small
metal parts. Sample (A-1) was immersed sequentially in Tanks 3, 4,
and 6-12. A black coating was observed on the conductive yarns on
the fabric, while the non-conductive yarns retained only a slight
discoloration from excess electrocoating formula that had not been
successfully rinsed out. The fabric sample was then carried by the
rack conveyor system into a series of ovens to dry and cure the
electrocoating. The entry temperature of the curing ovens was set
at 400.degree. F., decreasing to 250.degree. F. at the exit. Total
dwell time in the curing ovens was about 20 minutes. The fabric
sample shrank a small amount during the curing process. Initial
continuity checks were made using a multimeter attached to the
snaps at each end of the fabric sample. All fabric samples retained
electrical continuity through the part after processing, including
continuity from warp to weft yarns. Attempts to measure the
conductivity of the coated conductive yarns using the multimeter
probes directly on the conductive yarns were unsuccessful,
indicating that the deposited coating electrically insulated the
conductive yarns.
[0051] Experiment II: Fabric sample (A-2) was snapped to a metal
frame and loaded into the rack conveyor system of a commercial
electrocoating process as shown in FIG. 6. The coating system used
was an 800-series black cationic epoxy from PPG, typically used for
automotive and other small metal parts. In this case, the fabric
sample was sent through the entire electrocoating process, tanks
1-12, identical to metal parts processing. A black coating was
observed on the conductive yarns on the fabric, while the
non-conductive yarns retained only a slight discoloration from
excess electrocoating formula that had not been successfully rinsed
out. The fabric sample was then carried by the rack conveyor system
into a series of ovens to dry and cure the electrocoating. The
entry temperature of the curing ovens was set at 400.degree. F.,
decreasing to 250.degree. F. at the exit. Total dwell time in the
curing ovens was about 20 minutes. The fabric sample shrank a small
amount during the curing process. Initial continuity checks were
made using a multimeter attached to the snaps at each end of the
fabric sample. All fabric samples retained electrical continuity
through the part after processing, including continuity from warp
to weft yarns. Attempts to measure the conductivity of the coated
conductive yarns using the multimeter probes directly on the
conductive yarns were unsuccessful, indicating that the deposited
coating electrically insulated the conductive yarns.
[0052] Experiment III: Fabric sample (B) was snapped to a metal
frame and loaded into the rack conveyor system of a commercial
electrocoating process. The coating system used was an 800-series
black cationic epoxy from PPG, typically used for automotive and
other small metal parts. Sample (B) was immersed in Tanks 3, 4, and
6-12. A black coating was observed on the conductive yarns on the
fabric, while the non-conductive yarns retained only a slight
discoloration from excess electrocoating formula that had not been
successfully rinsed out. The fabric sample was then carried by the
rack conveyor system into a series of ovens to dry and cure the
electrocoating. The entry temperature of the curing ovens was set
at 400.degree. F., decreasing to 250.degree. F. at the exit. Total
dwell time in the curing ovens was about 20 minutes. The fabric
sample (B) shrank a slightly larger amount than samples (A-1) and
(A-2) during the curing process. Initial continuity checks were
made using a multimeter attached to the snaps at each end of the
fabric sample. All fabric samples retained electrical continuity
through the part after processing, including continuity from warp
to weft yarns. Attempts to measure the conductivity of the coated
conductive yarns using the multimeter probes directly on the
conductive yarns were unsuccessful, indicating that the deposited
coating electrically insulated the conductive yarns.
[0053] FIG. 8 is a microscope image of the top of the electrocoated
fabric and FIG. 9 is a cross-sectional image of the electrocoated
fabric. In FIG. 8, the white-looking yarns are the nonconductive
yarns and the dark-looking yarns are insulation coated conductive
yarns. Referring now to FIG. 9, the white-looking yarns are the
nonconductive yarns and one can see the conductive elements
(grayish fibrous material) surrounded by the conductive coating
(the dark-looking material). As can be seen from FIG. 9, most of
the coating (dark areas) surrounded the conductive elements with
little to none on the nonconductive elements. Measurements indicate
that less than 10% of the total amount of coating deposited was
deposited on the nonconductive elements. The resultant fabric
maintained its electrical connections through the fabric and an air
permeability of 47.2 cfm at 125 Pa using TexTest air permeability
test equipment (ASTM D737). The air permeability was greater than
98% of the air permeability of the untreated fabric.
[0054] The invention has been described in detail with particular
reference to certain preferred embodiments thereof, but it will be
understood that variations and modifications can be effected within
the spirit and scope of the invention.
* * * * *