U.S. patent application number 10/518092 was filed with the patent office on 2006-03-16 for magnet wire insulation comprising a high-temperature sulfone polymer blend.
This patent application is currently assigned to SOLVAY ADVANCED POLYMERS, LLC. Invention is credited to Glenn W. Cupta, Mohammad Jamal El-Hibri, Shari Weinberg.
Application Number | 20060057380 10/518092 |
Document ID | / |
Family ID | 30000458 |
Filed Date | 2006-03-16 |
United States Patent
Application |
20060057380 |
Kind Code |
A1 |
Weinberg; Shari ; et
al. |
March 16, 2006 |
Magnet wire insulation comprising a high-temperature sulfone
polymer blend
Abstract
A magnet wire containing a melt processable, thermoplastic resin
blend insulative coating developed for use in high temperature
electrical insulation systems. The invention relates to a high
temperature electrical insulation containing a sulfone polymer
blend for particular use with magnet wire. The sulfone polymer
blend contains two poly(aryl ether sulfones), such as
polyphenylsulfone and polysulfone.
Inventors: |
Weinberg; Shari; (Atlanta,
GA) ; Cupta; Glenn W.; (Roswell, GA) ;
El-Hibri; Mohammad Jamal; (Atlanta, GA) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
SOLVAY ADVANCED POLYMERS,
LLC
Alpharetta
GA
|
Family ID: |
30000458 |
Appl. No.: |
10/518092 |
Filed: |
June 19, 2003 |
PCT Filed: |
June 19, 2003 |
PCT NO: |
PCT/US03/19318 |
371 Date: |
August 4, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60389484 |
Jun 19, 2002 |
|
|
|
Current U.S.
Class: |
428/375 |
Current CPC
Class: |
C08L 81/06 20130101;
H01B 3/301 20130101; C08L 81/06 20130101; Y10T 428/2933 20150115;
C08L 81/00 20130101 |
Class at
Publication: |
428/375 |
International
Class: |
D02G 3/00 20060101
D02G003/00 |
Claims
1. An insulated magnet wire comprising a metallic magnet wire and a
polymer composition insulation coating, said polymer composition
insulation coating comprising a blend of a polyphenylsulfone (PPSF)
and a polysulfone (PSF), wherein the PPSF comprises the following
structural repeat unit: ##STR10## and the PSF comprises the
following structural repeat unit: ##STR11##
2. The insulated magnet wire according to claim 1, wherein the
insulation coating comprises from about 20 wt. % to about 80 wt. %
PPSF and about 20 wt. % to about 80 wt. % PSF based on the total
polymer weight.
3. The insulated magnet wire according to claim 2, wherein the
insulation coating comprises greater than 50 wt. % PPSF based on
the total polymer weight.
4. The insulated magnet wire according to claim 1, wherein the
insulation coating comprises about 70 wt. % PPSF and about 30 wt. %
PSF based on the total polymer weight.
5. The insulated magnet wire according to claim 1, wherein the
insulation coating comprises about 55 wt. % PPSF and about 45 wt. %
PSF based on the total polymer weight.
6. The insulated magnet wire according to claim 1, wherein the
insulation coating further comprises at least one reinforcing
filler, fiber, pigment and/or additive.
7. The insulated magnet wire according to claim 6, wherein the
fiber is selected from the group consisting of glass fiber,
asbestos, synthetic polymeric fiber, aluminum silicate fiber,
wollastonite and rock wool fiber.
8. The insulated magnet wire according to claim 6, wherein the
reinforcing filler is selected from the group consisting of glass,
calcium silicate, silica, clays, talc and mica.
9. The insulated magnet wire according to claim 6, wherein the
pigment is selected from the group consisting of carbon black,
titanium dioxide, zinc oxide, iron oxide, cadmium red and iron
blue.
10. The insulated magnet wire according to claim 9, wherein the
pigment is titanium dioxide or zinc oxide.
11. The insulated magnet wire according to claim 1, wherein the
PPSF can be a copolymer wherein up to less than 50 mole % of the
biphenol residue structural units are substituted with one or more
aromatic dihydroxy compound residues other than those from
biphenol, and wherein the aromatic dihydroxy compound residues
other than those from biphenol are selected from the group
consisting of 4,4'-isopropylidenediphenol,
4,4'-dihydroxydiphenylether, 4,4'-dihydroxydiphenylsulfone,
4,4'-dihydroxybenzophenone, 1,4-bis(4-hydroxyphenyl) benzene, and
hydroquinone.
12. The insulated magnet wire according to claim 1, wherein the PSF
can be a copolymer wherein up to less than 50 mole % of the
bisphenol A residue structural units are substituted with one or
more aromatic dihydroxy compound residues other than those from
bisphenol A, and wherein the aromatic dihydroxy compound residues
other than those from bisphenol A are selected from the group
consisting of 4,4'-dihydroxydiphenylether,
4,4'-dihydroxydiphenylsulfone, 4,4'-dihydroxybenzophenone,
1,4-bis(4-hydroxyphenyl) benzene, 4,4'-dihydroxydiphenyl and
hydroquinone.
13. A method for providing an insulated magnet wire with a polymer
composition insulation coating, said method comprising coating a
polymer composition insulation on a bare metallic magnet wire, said
polymer composition insulation coating comprising a blend of a
polyphenylsulfone (PPSF) and a polysulfone (PSF), wherein the PPSF
comprises the following structural repeat unit: ##STR12## and the
PSF comprises the following structural repeat unit: ##STR13##
14. The method according to claim 13, wherein the insulation
coating comprises from about 20 wt. % to about 80 wt. % PPSF and
about 20 wt. % to about 80 wt. % PSF based on the total polymer
weight.
15. The method according to claim 14, wherein the insulation
coating comprises greater than 50 wt. % PPSF based on the total
polymer weight.
16. The method according to claim 13, wherein the insulation
coating comprises about 70 wt. % PPSF and about 30 wt. % PSF based
on the total polymer weight.
17. The method according to claim 13, wherein the insulation
coating comprises about 55 wt. % PPSF and about 45 wt. % PSF based
on the total polymer weight.
18. The method according to claim 13, wherein the coating step is
selected from the group consisting of melt extruding, solvent
coating, powder coating and film wrapping.
19. The method according to claim 18, wherein the coating step is
melt extruding.
20. The method according to claim 13, wherein the metallic magnet
wire is preheated prior to extruding the insulation coating on the
metallic magnet wire.
21. The method according to claim 13, wherein the insulation
coating is melt filtered prior to being extruded on the metallic
magnet wire.
22. The method according to claim 13, wherein said melt extruding
step is free of solvent.
23. The method according to claim 13, further comprising an
optional baking step to cure said coating.
24. The method according to claim 23, further comprising cooling
the cured coating on said metallic magnet wire.
25. The method according to claim 13, wherein the PPSF can be a
copolymer wherein up to less than 50 mole % of the biphenol residue
structural units are substituted with one or more aromatic
dihydroxy compound residues other than those from biphenol, and
wherein the aromatic dihydroxy compound residues other than those
from biphenol are selected from the group consisting of
4,4'-isopropylidenediphenol, 4,4'-dihydroxydiphenylether,
4,4'-dihydroxydiphenylsulfone, 4,4'-dihydroxybenzophenone,
1,4-bis(4-hydroxyphenyl) benzene, and hydroquinone.
26. The method according to claim 13, wherein the PSF can be a
copolymer wherein up to less than 50 mole % of the bisphenol A
residue structural units are substituted with one or more aromatic
dihydroxy compound residues other than those from bisphenol A, and
wherein the aromatic dihydroxy compound residues other than those
from bisphenol A are selected from the group consisting of
4,4'-dihydroxydiphenylether, 4,4'-dihydroxydiphenylsulfone,
4,4'-dihydroxybenzophenone, 1,4-bis(4-hydroxyphenyl) benzene,
4,4'-dihydroxydiphenyl and hydroquinone.
27. A high temperature electrical insulation system comprising said
insulated magnet wire according to claim 1.
28. The high temperature electrical insulation system according to
claim 27, wherein the high temperature electrical insulation system
is selected from the group consisting of voltage transformers,
motors, generators, alternators, solenoids, and relays.
29. A high temperature electrical insulation system comprising an
insulated magnet wire obtained by the process according to claim
13.
30. (canceled)
31. The high temperature electrical insulation system according to
claim 27, wherein the metallic magnet wire is in contact with an
insulating fluid selected from the group consisting of a mineral
oil, a silicone oil, a vegetable oil, a synthetic oil, and mixtures
thereof.
32. An electrical device comprising said insulated magnet wire
according to claim 1.
33. The electrical device according to claim 32, wherein said
electrical device is selected from the group consisting of voltage
transformers, motors, generators, alternators, solenoids, and
relays.
34. The high temperature electrical insulation system according to
claim 29, wherein the high temperature electrical insulation system
is selected from the group consisting of voltage transformers,
motors, generators, alternators, solenoids, and relays.
35. The high temperature electrical insulation system according to
claim 29, wherein the metallic magnet wire is in contact with an
insulating fluid selected from the group consisting of a mineral
oil, a silicone oil, a vegetable oil, a synthetic oil, and mixtures
thereof.
Description
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/389,484, filed on Jun. 19, 2002.
FIELD OF THE INVENTION
[0002] This invention relates to a magnet wire comprising a melt
processable, thermoplastic resin blend insulative coating developed
especially for use in high temperature electrical insulation
systems. More particularly, this invention relates to a high
temperature electrical insulation system containing sulfone
polymers for use with magnet wire and wherein the sulfone polymers
comprise a blend of two poly(aryl ether sulfones). The blend
exhibits improved electrical insulation and long term thermal and
environmental aging stability relative to polysulfone.
BACKGROUND OF THE INVENTION
[0003] Polymeric materials are used in magnet wire insulation
coatings. Although thermoset materials are commonly used, magnet
wire insulation coatings can include thermoplastics. These
polymeric materials are applied as extruded coatings, wrapped
films, powder coatings, and solvent-based enamels. Paper is also
commonly used as wire wrap insulation.
[0004] Examples of thermoplastic polymers used in magnet wire
insulation systems include poly(aryl ether sulfones), such as
polyphenylsulfone. A magnet wire comprising a polyphenylsulfone
resin insulation is commercially available under the tradename
Reymag.RTM. produced by Hanover Manufacturing Corporation.
Polyphenylsulfone is a tough linear polymer that possesses a number
of attractive features such as excellent high temperature
resistance, good electrical properties, high ductility, good
toughness, and very good hydrolytic stability. Polyphenylsulfone is
available from Solvay Advanced Polymers, LLC, under the trademark
of Radel.RTM. R. It corresponds to the following repeat unit
formula: ##STR1## and has a Tg of about 220.degree. C. It is
produced by the polycondensation of biphenol with
4,4'-dichlorodiphenyl sulfone as described in Canadian Patent No.
847,963. Polyphenylsulfone is an expensive resin due to the high
cost of biphenol.
[0005] High temperature insulation systems for magnet wire are
required in many applications including transformers, motors,
generators, solenoids, and relays. Requirements for such products
include high efficiency or low dissipation at use temperatures;
high continuous use temperatures; resistance to insulating fluids
such as a mineral oil, a silicone oil, a vegetable oil, a synthetic
oil, and mixtures thereof; and ability to withstand overload
conditions. Not only is the magnet wire coating required to provide
dielectric insulation, but it also must provide protection against
abrasion, mechanical stress, and corrosion. Thus, magnet wire
insulation systems have many more stringent requirements over mere
dielectric insulation. There is, therefore, a continual need in the
art to economically improve the performance of insulation systems
for magnet wire.
SUMMARY OF THE INVENTION
[0006] There exists a need in the magnet wire art for high
performance insulation coatings that exhibit robust electrical
insulation, long term thermal aging stability, and environmental
resistance. There exists a need in the magnet wire art to
economically produce high performance magnet wire insulation
coatings, by reducing the amount of expensive resins used in the
insulation coating. Further, there exists a need in the magnet wire
art to produce high performance insulation coatings containing
minimal amounts of consumable performance and stability additives.
In addition, there exists a need in the magnet wire art to be able
to economically and reliably insulate the wire by extrusion
coating, solvent coating, film wrapping or powder coating.
[0007] In addition, there exists a need in the electrical device
art for an electrical device comprising insulated magnet wire that
can withstand long term exposure to high temperature. There further
exists a need in the electrical device art for an electrical device
comprising insulated magnet wire that has superior chemical
resistance during long term exposure to oils.
[0008] These and other needs are met by certain embodiments of the
present invention, that provide an insulated magnet wire comprising
a metallic magnet wire and a polymer composition insulation
coating, wherein the insulation coating comprises a blend of
polyphenylsulfone (PPSF) and polysulfone (PSF), wherein the PPSF
comprises the following structural repeat unit: ##STR2## and the
PSF comprises the following structural repeat unit: ##STR3##
[0009] The earlier-stated needs are further met by an electrical
device comprising an insulated magnet wire comprising a metallic
wire and a polymer composition insulating coating, wherein the
insulation coating comprises a blend of polyphenylsulfone (PPSF)
and polysulfone (PSF), wherein the PPSF comprises the following
structural repeat unit: ##STR4## and the PSF comprises the
following structural repeat unit: ##STR5##
[0010] The earlier-stated needs are further met by certain
embodiments of the present invention that provide an insulated
magnet wire comprising a metallic magnet wire and a polymer
composition insulation coating comprising from about 20 wt. % to
about 80 wt. % PPSF and about 20 wt. % to about 80 wt. % PSF based
on the total polymer weight.
[0011] Additional advantages and aspects of the present invention
will become readily apparent to those skilled in the art from the
following detailed description, wherein embodiments of the present
invention are shown and described, simply by way of illustration of
the best mode contemplated for practicing the present invention. As
will be described, the present invention is capable of other and
different embodiments, and its several details are susceptible to
modification in various obvious respects, all without departing
from the spirit of the present invention. Accordingly, the
description is to be regarded as illustrative in nature, and not as
limitative.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 illustrates an insulated magnet wire according to an
embodiment of the present invention.
[0013] FIG. 2 illustrates an electrical device according to an
embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0014] The present invention provides magnet wire with a robust
electrical insulation coating. The present invention provides a
high performance poly(aryl ether sulfone) blend which exhibits
improved electrical insulation and long term thermal aging
stability. The present invention allows for the economical
production of a magnet wire comprising a high performance poly(aryl
ether sulfone) blend coating with optional amounts of performance
and stability additives. The present invention allows for the
production of an insulated magnet wire with a reduced amount of an
expensive resin, such as PPSF, which retains the high performance
properties of PPSF. Coupled with all the above benefits, the
present invention allows for the economical fabrication of metallic
magnet wire with a thermoplastic blend containing poly(aryl ether
sulfones). These benefits are provided by an insulated magnet wire
comprising a metallic magnet wire and a polymer composition
insulation coating, said polymer composition insulation coating
comprising a blend of polyphenylsulfone (PPSF) and polysulfone
(PSF). The PPSF comprises the following structural repeat unit:
##STR6## [0015] and the PSF comprises the following structural
repeat unit: ##STR7##
[0016] PPSF is available from commercial sources, including Solvay
Advanced Polymers, LLC, under the trademark of Radel.RTM. R.
Suitable PPSF for certain embodiments of the present invention has
a Tg of about 220.degree. C. PPSF is produced by the
polycondensation of biphenol with 4,4-dichlorodiphenyl sulfone as
described in Canadian Patent No. 847,963, the entire disclosure of
which is incorporated herein. In certain embodiments, the PPSF can
be a copolymer wherein up to less than 50 mole % of the biphenol
residue structural units are substituted with one or more aromatic
dihydroxy compound residues other than those from biphenol. The
aromatic dihydroxy compound residues other than those from biphenol
are selected from the group consisting of
4,4'-isopropylidenediphenol (bisphenol A),
4,4'-dihydroxydiphenylether (bisphenol O),
4,4'-dihydroxydiphenylsulfone (bisphenol S),
4,4'-dihydroxybenzophenone, 1,4-bis(4-hydroxyphenyl) benzene, and
hydroquinone.
[0017] PSF is available from commercial sources, including from
Solvay Advanced Polymers, LLC, under the trademark of UDEL.RTM..
Suitable PSF for certain embodiments of the present invention and
has a Tg of about 185.degree. C. PSF is made via the nucleophilic
polycondensation of bisphenol-A di-sodium salt with
4,4'-dichlorodiphenyl sulfone, as described in U.S. Pat. No.
4,108,837, the entire disclosure of which is incorporated herein.
In certain embodiments, the PSF can be a copolymer wherein up to
less than 50 mole % of the bisphenol A residue structural units are
substituted with one or more aromatic dihydroxy compound residues
other than those from bisphenol A. The aromatic dihydroxy compound
residues other than those from bisphenol A are selected from the
group consisting of 4,4'-dihydroxydiphenylether (bisphenol O),
4,4'-dihydroxydiphenylsulfone (bisphenol S),
4,4'-dihydroxybenzophenone, 1,4-bis(4-hydroxyphenyl) benzene,
4,4'-dihydroxydiphenyl (biphenol) and hydroquinone.
[0018] Properties of the PPSF/PSF blend provide benefits in the
end-use applications of magnet wire. For example, PPSF/PSF blend
coated magnet wire can be wound faster with fewer insulation tears
than paper wrapped wire. The required insulation thickness is
generally less than that required for paper wrapped wire which can
yield smaller windings. Moreover, because the PPSF/PSF blend has a
low equilibrium moisture content, magnet wire coils can be dried
quickly and do not contribute to hydrolysis of insulating oils. In
addition, the PPSF/PSF blend can perform under higher temperatures
and more rigorous conditions in oil environments thereby reducing
susceptibility to damage under overload conditions. The end result
is increased reliability and longer service time. Furthermore,
PPSF/PSF blend coated magnet wire uses a reduced amount of
expensive PPSF resin, while retaining the high performance
properties of PPSF required for magnet wire applications.
[0019] In FIG. 1, an insulated magnet wire 10 according to an
embodiment of the present invention is depicted. Insulated magnet
wire 10 comprises magnet wire 12 which can be comprised of a
copper, aluminum and the like. Magnet wire 12 is coated with
insulation coating 14 that is applied to magnet wire 12 to provide
a continuous coating.
[0020] Other embodiments of the present invention include an
insulated magnet wire comprising a metallic magnet wire and a
polymer composition insulation coating that comprises from about 20
wt. % to about 80 wt. % PPSF and about 20 wt. % to about 80 wt. %
PSF based on the total polymer weight. In certain embodiments of
the present invention the insulated magnet wire comprises a
metallic magnet wire and a polymer composition insulation coating
that comprises greater than 50 wt. % PPSF based on the total
polymer weight. In other certain embodiments of the present
invention the insulated magnet wire comprises a metallic magnet
wire and a polymer composition insulation coating that comprises
from about 30 wt. % to about 70 wt. % PPSF and about 30 wt. % to
about 70 wt. % PSF based on the total polymer weight. In other
certain embodiments of the present invention the insulated magnet
wire comprises a metallic magnet wire and a polymer composition
insulation coating that comprises from about 40 wt. % to about 60
wt. % PPSF and about 40 wt. % to about 60 wt. % PSF based on the
total polymer weight. Other certain embodiments of the present
invention include a magnet wire composition comprising a metallic
magnet wire and a polymer composition insulation coating comprising
about 70 wt. % PPSF and about 30 wt. % PSF based on the total
polymer weight. Other embodiments of the present invention include
a magnet wire comprising a metallic magnet wire and a polymer
composition insulation coating comprising about 55 wt. % PPSF and
about 45 wt. % PSF based on the total polymer weight.
[0021] The PPSF/PSF blend of the present invention, may optionally
include reinforcing filler, fiber, pigments, additives, and the
like. Representative fibers which may serve as reinforcing media
include glass fibers, asbestos, synthetic polymeric fibers,
aluminum silicate fibers, wollastonite, rock wool fibers, etc.
Representative filler and other materials include glass, calcium
silicate, silica, clays, talc, mica; pigments such as carbon black,
titanium dioxide, zinc oxide, iron oxide, cadmium red and iron
blue; polymers such as polyethersulfone; and other additives such
as, alumina trihydrate, sodium aluminum carbonate, and barium
ferrite. Additional additives commonly employed in the magnet wire
art such as thermal stabilizers, ultraviolet light stabilizers,
plasticizers, and the like, may be included. Titanium dioxide and
zinc oxide pigments are well suited for use in certain embodiments
of the present invention.
[0022] Other certain embodiments of the present invention include a
method for providing an insulated magnet wire with a polymer
composition insulation coating, the method comprising the step of
coating a polymer composition insulation on a metallic magnet wire.
The polymer composition insulation coating comprises a blend of
polyphenylsulfone (PPSF) and polysulfone (PSF), wherein the PPSF
comprises the following structural repeat unit: ##STR8## [0023] and
the PSF comprises the following structural repeat unit:
##STR9##
[0024] Other embodiments of the present invention include a method
of providing an insulated magnet wire with a polymer composition
insulation coating, wherein the insulation coating comprises from
about 20 wt. % to about 80 wt. % PPSF and about 20 wt. % to about
80 wt. % PSF based on the total polymer weight. In certain
embodiments of the present invention the insulated magnet wire
comprises a metallic magnet wire and a polymer composition
insulation coating that comprises greater than 50 wt. % PPSF based
on the total polymer weight. In other certain embodiments of the
present invention the insulated magnet wire comprises a metallic
magnet wire and a polymer composition insulation coating that
comprises from about 30 wt. % to about 70 wt. % PPSF and about 30
wt. % to about 70 wt. % PSF based on the total polymer weight. In
other certain embodiments of the present invention the insulated
magnet wire comprises a metallic magnet wire and a polymer
composition insulation coating that comprises from about 40 wt. %
to about 60 wt. % PPSF and about 40 wt. % to about 60 wt. % PSF
based on the total polymer weight. Other certain embodiments of the
present invention include a method of providing an insulated magnet
wire with a polymer composition insulation coating, wherein the
insulation coating comprises about 70 wt. % PPSF and about 30 wt. %
PSF based on the total polymer weight. Other embodiments of the
present invention include a method of providing an insulated magnet
wire with a polymer composition insulation coating, wherein the
insulation coating comprises about 55 wt. % PPSF and about 45 wt. %
PSF based on the total polymer weight.
[0025] Additional advantages realized through the use of present
invention's insulated magnet wire is the ability to fabricate
insulated magnet wire using multiple techniques. Insulation can be
applied by wrapping plastic extruded or solvent cast film. It can
also be applied by solvent coating like other common enamels or by
known powder coating techniques. In the case of solvent coating, an
oven step is used only for the purpose of driving off solvent
rather than curing and driving off solvent.
[0026] The most efficient and cost effective method is to melt
extrude the coating directly on the magnet wire. In melt extrusion
fabrication, solvent recovery systems are not required and curing
steps are optional. Extruders required to provide the necessary
throughput for wire coating applications are quite small and
economical to install. The excellent thermal stability of the
PPSF/PSF insulation coating also allows melt extrusion processing
of magnet wire at fabrication temperatures up to 400.degree. C.
Magnet wire can be prepared either by conforming, drawing, or
rolling. The PPSF/PSF insulation coating of the present invention
may be used with round and shaped aluminum and copper wire of
varying size.
[0027] Other embodiments of the present invention include forming
the magnet wire and then coating the wire by a metal conforming
line and melt extrusion coating line in tandem. A variety of round
and rectangular wire sizes are produced via this technique. The
metallic magnet wire is particularly suitable for use in oil-filled
transformers.
[0028] Other certain embodiments of the present invention include a
method for providing an insulated magnet wire comprising the
PPSF/PSF polymer composition insulation coating. The method
includes the step of melt extruding. The melt extrusion process
comprises providing a supply of metal feed stock and continuously
feeding the feed stock into a rotary extrusion press and
continuously forming the magnet wire. The magnet wire can be formed
in tandem with the extrusion operation or it can be formed in a
separate step and heated prior to the polymer composition coating.
The metal wire can be formed as described above with a rotary
extrusion press, or it may be drawn. It may also be formed by
rolling or flattening round wire into a rectangular shape. The
extruded magnet wire is moved through extrusion die at a set speed.
In certain embodiments of the present invention, sulfone
polymer-based insulation coating of the present invention is
extruded using a tubing or semi-tubing technique which involves a
crosshead assembly and a tip and die configuration that contains
flow channels designed to maximize the uniformity of the coating on
shaped magnet wire. The tube is extruded around and spaced from the
extruded magnet wire, and the tube is extruded such that the
thickness of the polymer material is reduced or drawn down before
it contacts the extruded magnet wire. A vacuum is provided between
the extruded magnet wire and the polymeric material being extruded
thereby causing atmospheric pressure to progressively press the
extruded polymeric material into contact with the extruded magnet
wire. Application of the polymer through means of pressure
extrusion technique may also be suitable. In pressure extrusion,
metal wire is brought into contact with molten polymer within the
crosshead die to form the coating and no tube is extruded. The
magnet wire is extruded in a heated condition, but the temperature
is controlled to a suitable range for application of the polymeric
material to the wire. The temperature is selected to control the
cooling rate of the polymer on the wire which in turn can minimize
stress in the coating and maximize adhesion of the coating to the
magnet wire. The particular metal of the magnet wire is not
critical and may include any commonly used electrically conductive
material including, for example, aluminum, aluminum-based alloys,
copper, and copper-based alloys.
[0029] Other embodiments of the present invention include using the
insulated magnet wire of the present invention in high temperature
electrical insulation systems. Suitable high temperature electrical
insulation systems include electrical devices, including voltage
transformers, motors, generators, alternators, solenoids, relays,
and the like. In FIG. 2, transformer 20, according to an embodiment
of the present invention is depicted. Transformer 20 comprises two
coils 21a, 21b of insulated magnet wire, which are wrapped around
core 30. Transformer 20 can be a step-up transformer, wherein coil
21a will be a primary coil (i.e. has an electric current passed
through it) and coil 21b will be a secondary coil (has an electric
current induced within it). Alternatively, transformer 20 can be a
step-down transformer, wherein coil 21a will be a secondary coil
(has an electric current induced within it) and coil 21b will be a
primary coil (i.e. has an electric current passed through it). In
either embodiment, core 30 is a magnet comprised of iron, or the
like.
[0030] Properties of the PPSF/PSF blend, Example 1, are depicted in
Table 1, and are compared with the PPSF resin, Control 1. The
PPSF/PSF blend absorbs slightly less moisture than PPSF and
exhibits greater melt stability than PPSF. Melt stability is
characterized by measuring the ratio of melt viscosity measured at
50 reciprocal seconds after exposure to 410.degree. C. for 40
minutes to the melt viscosity measured after 10 minutes. The
PPSF/PSF blend exhibits a viscosity ratio of 1.3 versus 1.5 which
is typical of PPSF resins. Example 1 is a 70 wt. %/30 wt. % based
on the total polymer weight RADEL.RTM. R PPSF/UDEL.RTM. PSF blend.
As demonstrated, the PPSF/PSF blend has comparable superior flame
resistance, mechanical strength, and minimum moisture absorption,
as the PPSF resin, Control 1. These properties demonstrate the
compatibility of the PPSF/PSF blend with magnet wire applications.
Further, the PPSF/PSF blend exhibits superior properties over the
PSF resin, Comparative Example 1. The supertough behavior of the
PPSF/PSF blend is evidenced by the high notched Izod impact
strength. Further the PPSF/PSF blend exhibits superior thermal
properties over the PSF resin, as evidenced by the heat deflection
temperature results in Table 1. It is noted that the glass
transition temperature for the PPSF/PSF blend is 185/220 due to the
immiscible blend of the two polymers (i.e. one glass transition
temperature will occur for each polymer). TABLE-US-00001 TABLE 1
Selected Properties of Polyphenylsulfone and a Polyphenylsulfone
Blend Example 1 Compara- 70 wt. % tive PPSF/ Example 1 Control 1 30
wt. % Physical Method Units PSF PPSF PSF Blend Moisture Absorption
ASTM -- After 24 hrs D-570 % 0.3 0.37 0.30 At Equilibrium D-570 %
0.6 1.1 0.95 Specific Gravity D-792 1.24 1.29 1.28 Mechanical
Tensile Strength D-638 MPa 70 70 70 Elongation at Break D-638 %
50-100 90 60 Flexural Strength D-790 MPa 105 105 105 Notched D-256
J/m 69 694 265 Izod Impact Un-notched Izod D-256 J/m 0 Breaks 0
Breaks 0 Breaks Thermal Glass Transition .degree. C. 185 220
185/220 Temp. Heat D-648 .degree. C. 174 207 200 Deflection Temp.
Electrical Dielectric Constant after 48 hours of conditioning at
23.degree. C. and 50% RH @ 1 MHz D-150 -- 3.1 3.45 3.40
Flammability Limiting Oxygen D-2863 % 26 38 36 Index
[0031] Relevant performance characteristics of aluminum wire coated
with the PPSF/PSF insulation blend were evaluated and the results
are given in Table 2. It can be seen in Table 2 that wire coated
with the PPSF/PSF blend exhibits good flexibility, adhesion, and
elongation, comparable to aluminum wire coated with the more
expensive PPSF resin. The PPSF/PSF magnet wire insulation is also
resistant to heat shock, and can maintain dielectric strength at
temperatures up to 200.degree. C. At temperatures of 200.degree.
C., the dissipation remains at about 0.007 which is far lower than
many polyvinylformal based resins and paper. Thus, the magnet wires
coated with the present invention's insulative coating are suitable
for use with high temperature systems. TABLE-US-00002 TABLE 2 NEMA
MW 1000 Quality Tests of Magnet Wire Using Test Methods NEMA MW
1000/ASTM D-1676. All measurements made by Eltek International
Laboratories on rectangular aluminum magnet wire. Test Control 1
Example 1 Aluminum Bare Wire Width 0.3253 in 0.3251 in Thickness
0.1137 in 0.1138 in Overall Dimensions Width 0.3367 in 0.3349 in
Thickness 0.1208 in 0.1201 in Increase in Dimension Width 0.1140 in
0.0098 in Thickness 0.0071 in 0.0063 in Average Film Build Width
0.0057 in 0.0049 in Thickness 0.0036 in 0.0032 in Elongation to
Break 20% (Rectangular Wire) 33% 35% (Round Wire) (Rectangular
Wire) Flatwise Bend No cracks visible in the film No cracks visible
in the film coating coating Egdewise Bend No cracks visible in the
film No cracks visible in the film coating coating Windability No
cracks visible in the film No cracks visible in the film coating
coating Heat Shock No cracks visible in the film No cracks visible
in the film coating after conditioning at coating after
conditioning at 260.degree. C. 175.degree. C. Thermoplastic Flow
265.degree. C. 245.degree. C. Breakdown Voltage after 48 hours of
conditioning at 23.degree. C. and 50% RH 23.degree. C. 10.88 kV
9.30 kV 150.degree. C. 8.96 kV 9.32 kV 180.degree. C. 8.79 kV 8.48
kV 200.degree. C. 8.90 kV 7.07 kV Dissipation after 48 hours of
conditioning at 23.degree. C. and 50% Rh 23.degree. C. 0.0022
0.0016 150.degree. C. 0.0007 0.0008 180.degree. C. 0.0021 0.0042
200.degree. C. 0.0042 0.0069
[0032] The insulation coating of the present invention also retains
properties after over 5 months of aging in hot transformer oil, and
the results are given in Table 3. The wires were coated with resin
by drawing them through a melt-flow apparatus. By passing the wire
through the die, and keeping the apparatus primed with resin
pellets, a coating was passed through the die and on to the bare
wire. For each coated wire, a length was wrapped around a rod 1/4''
in diameter, and 1/16'' in diameter to resemble a spring. Two
straight lengths of wire at approximately 2-3'' were also cut. The
wires were then placed into a glass-lined Parr reactor with
sufficient transformer oil to submerge the wires. The reactor was
placed in an oven and the temperature was set to 150.degree. C. The
wires were subjected to the heated oil in the reactor at a
temperature of about 150.degree. C..+-.1.degree. C. The reactor was
periodically removed from the oven, cooled to room temperature, and
the wire samples were removed from the reactor for evaluation.
Following each evaluation the wires were re-submerged in the oil
contained in the glass-lined Parr reactor. Evaluations were taken
at different intervals, and the results are summarized in Table
3.
[0033] The PPSF resin (RADEL.RTM. R) does not exhibit any failure
in this hot oil environment. Moreover, it is evident that the resin
blend (PPSF/PSF) of the present invention did not exhibit
stress-cracking behavior even after a period of 5 months. The
results are unexpected in view of the proximity of the hot oil
environment temperature to the glass transition temperatures (Tg)
of the PSF contained in the blend and the increased environmental
sensitivity that might be expected for the PSF at this temperature.
The PSF resin has a lower glass transition temperature
(Tg=185.degree. C.), compared to the PPSF resin (Tg=220.degree.
C.). Further, the test sample containing the PSF resin (UDEL.RTM.)
exhibited stress-cracking behavior after exposure to the silicone
oil at 150.degree. C. after only one week. However, the resin blend
(70 wt. % PPSF/30 wt. % PSF) of the present invention did not
exhibit stress-cracking behavior during the hot oil aging
experiment. Thus, the PPSF/PSF resin blend used in the present
invention offers high performance properties that are
characteristic of the PPSF resin. TABLE-US-00003 TABLE 3 Hot
Transformer Oil Experiment RESIN DAY 1 DAY 20 DAY 48 DAY 56 DAY 97
DAY 145 DAY 156 PPSF Insulated Clean and Same as Same as Same as
Same as Same as wire free of Day 20 - Day 48 - Day 56 - Day 97 -
Day 145 - submerged cracks and no no no no no in oil crazing -
significant significant significant significant significant no
change change change change change significant change 70 wt. %
Insulated Clean and Same as Same as Same as Same as Same as PPSF/
wire free of Day 20 - Day 48 - Day 56 - Day 97 - Day 145 - 30 wt. %
submerged cracks and no no no no no PSF in oil crazing -
significant significant significant significant significant Blend
no change change change change change significant change PSF
Insulated Straight Same as Same as Same as Same as Same as wire
wires Day 20 - Day 48 - Day 56 - Day 97 - Day 145- submerged crazed
and no no no no no in oil springs significant significant
significant significant significant have change change change
change change cracks
[0034] The present invention enjoys industrial applicability in the
production of insulated magnet wire for use with high temperature
electrical insulation systems. The present invention is
particularly applicable in the production of insulated magnet wire
having a polymer insulation coating for use with high temperature
electrical insulation systems. Further, the present invention is
particularly applicable in the production of magnetic wire having a
poly(aryl ether sulfone) blend insulative coating, exhibiting
robust electrical insulation and long term thermal aging stability
along with improved economics over the current art.
[0035] Only the preferred embodiment of the present invention and a
few examples of its versatility are shown and described in the
present disclosure. They should not be construed to limit the scope
of the claims. It is understood by one of ordinary skill in this
art that the present invention is capable of use in various other
combinations and environments and is susceptible of changes or
modifications within the scope of the inventive concept as
expressed herein.
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