Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
RD-7266
~07S~
This invention is concerned with a new class of polye-ther-
amide-imide coresin blends. More particularly, the invention is
concerned with polyetheramide-imide blends with either phenolic
resins or epoxy resins, which blends exhibit melt viscosities
suitable for solventless dry powder coating and curing of poly-
etherimide insulating films on various substrates.
Solventless-dry powder coating materials which can be applied
in the absence of pressure to various substrates to provide
electrical insulation for materials employed in the manufacture
of electrical items such as motors, coils, magnet wires, etc.,
are highly desired materials. The identification of thermosetting
materials having the foregoing properties which sinter, flow,
level and cure at elevated temperatures in the absence of pressure
to form smooth, continuous substantially void-free film surfaces
especially when employed in fluidized resin bed coating processes
are especially desirable raw materials. Heretofore, insulating
materials generally having the electrical characteristics
`~ associated with cured polyetheramide-imide resins, i.e. polyether-
imides have not been available which permit the solventless-dry
powder coating of electrical items in fluidized bed coating
~; processes.
The novel compositions of our invention comprise poly-
etheramide-imide co-resin blends of the empirical formula
]m~-]l-m) a ( ) b
polyetheramide-imide resin co-resin
wherein A represents a polyamide (polyamic acid) structural unit
of polyetheramide~imide resin, B represen-ts a polyimide structural
unit of the polyetheramide-imide resin, wherein the polymer mole
fraction m represents a number greater than or equal to zero,
preferably a number less than about 0.5, C stands for a phenolic
resin or an epoxy resin the resin blend proportion fraction a
-
.,'.'' ~ . , ~ .
RD-7266
~7~
represents a number greater than zero, preferably a number greater
than about 0.4 and less than 1, and more preferably greater -than
about 0.50 and less than about 0.95, and the sum of a plus b
equals 1.0
The A and _ units of formula I comprise, herein and in the
appended claims respectively, un~ts of the following formulas:
-- O ()
II. HN-C \ ~ ~ C-NH-R - _
/~-ozo~
HO C C-OH
L o
polyamide unit
- O O .
III. N ~ 7~0~ ~ 1 N-R
O O
polyimide unit
Th~ O-Z-O units of the polyamide or polyimide units can be in
` the 3 or 3' or 4 or 4' positions and Z is a member of the class
consisting of (1) CH3 CH3 CH3
.,~ .
CH ~ CH3 CH3 Br Br CH3
- j f ~ / W and
- 2 -
~. ' , .
Br 10 75846 RD-7266
~ Br
/' ¢ ~ ~ C ~CH3 ) 2
B~ \
br
~and (2) divalent organic radicals of the general ~ormula
q ~ ,,
where X is a member selected from the class consisting of
divalent radicals of the formulas
O O
.. ..
_CyH2y-~ _ C- -S- ~ -O- and -S-,
O
where q is 0 or 1, y is a whole number from 1 to 5, the
divalent bonds o the _O-Z-O- radicals are situated on the
phthalic anhydrided-dexived units, e.g., in the 3,3'-,3,4'-,
4,3'_ or the 4,4'-positions, and R is a divalent organic
radical selected from the class consisting of ~2~ aromatic
hydrocarbon radicals having from 6-20 carbon atoms and
halogenated derivatives thereof, (b) alkylene radicals and
cycloalkylene radicals having ~rom 2-20 carbon atoms, C(2 8)
alkylene terminated polydiorganosiloxame, and (c) divalent
radicals included by the formula
( O ~ Q ~C3
where Q is a ~ember selected from the class consisting of
O O
-Q- ? " I
- C_ - S- 9 -S- ~ and -CxH2X ~
and x is a whole numbex ~rom 1 to 5 inclusive.
As used herein and in the appended claims, it is to be
understood that the polyetheramide-imide compositions em-
ployed in the invention can have any degree of amidization
_ 3 --
. .. .
'.~'~:': ' : ' . ,
-,:' : ' . :
RD-7266
~75~
or imidization, which is generally determined by their methods
of preparation well-known to those skilled in the art. Gen-
erally useful polyetheramide-imide compositions have an
intrinsic viscosity L ~ ~ greater than about O.lS deciliters
per gram, preferably from about 0 20 to about 0.35 deciliters
per gram~ or even higher as measured in N~-methyl pyrrolidone
(O.l N in lithium bromide) at 25 C
In general, the above-described polyetheramide-imide
resins can be obtained by any of the methods well-knowm to
those skilled in the art including the reaction of any
aromatic bistether anhydride)s of the formula
O o
, .. ..
IV.O / \ ~ O-Z-o ~ ~ ,
.. ..
~ O O
-; where Z is as defined hereinbefore with any diamino compound
of the formula
H2N-R-NEl2 ~
where R is as defined hereinbefore. Suitable methods include,
in general, solution polymerization reactions that are ad-
vantageously carried out employing well-known solvents, e g.
tetrahydrofuran, o-dichlorobenzene~toluene mixtures, m-cresol/
toluence mixtures, N-methyl pyrrolidone, dioxane/o-dichloro-
benzene/toluene mixtures~ N,~-dimethylformamide~ etc., in
which to effect intraction between the dianhydrides and the
diamines at temperatures of from about 25 to about 60 C
Alternatively~ the polyetheramide-imides can be prepared by
melt polymerization of any dianhydride of Formula IV with
any diamino compound of Formula V while heating a mixture
of the ingredients at elevated temperatures with concurrent
intermixing. Generally, melt polymerization temperatures
between about 180 to about 350 C. preferably about 185 to
-- 4 _
. .
.,~' .
R~-7266
~75~3~6
about 300 C, and more preferably from about 19~-210 C are
employed. Any order of addition of chain stoppers ordinarily
used in melt polymerization can be employed. The conditions
of the reaction and the proportion~ o~ ingredients can be
varied widely depending on the dec:ired molecular weight,
intrin~ic viscosity, and solvent resistance. In genexal,
equimolar amounts of diamine and dianhydride are employed,
however, a slight molar excess (about 1 to 10 mol percent)
of an aliphatic or aromatic dianhydride or (about 1 to 10
mol percent of an aliphatic or aromatic diamine can be
employed in order to effect the production of polyetheramide-
imides having terminal anhydride or amine groups, respectively~
Included among the many well-known methods of making
polyetheramide-imides that can be employed in the practice
of this invention are those disclosed in the following U~S.
patents: Heath et al 3,847~867 Dated November 12, 1974,
Williams 3,847,869 dated November 12, 1974, Takakoshi et al
3,850,885 dated November 26, 1974, ~ite 3,852"242 dated
December 3, 1974 and 3,855,178 dated December 17, 1974.
The aromatic bis(ether anhydride)s of Formula IV
include, for example,
2~2-bis ~4-(2,3-dicarboxyphenoxy) phenyl J propane
dianhydride;
4,4'-bis(2"3-dicarboxyphenoxy) diphenyl ether
dianhydride;
1,3-bis(2,3-dicarboxyphenoxy~ben2ene dianhydride;
4,4'-bis(2,3-dicarboxyphenoxy) diphenyl sulide
dianhydride
:
1, 4-bis (2,3-dicaxboxyphenoxy)benzene dianhydride;
4,4'_bis~2,3-dicaxboxyphenoxy) ben20phenone
dianhydride
4,4'-bis(2,3-dicarboxyphenoxy) diphenyl sulfone
dianhydridet
2,2-bis 4-(3,4-dicarboxyphenoxy)phenyl ~ propane
dianhydr ide:
107584~ RD-7266
4,4'-bis~3,4-dicarboxyphenoxy)diphenyl ether
dianhydride;
4~4'-bis(3,4-dicarboxyphenoxy)diphenyl sulfide
dianhydride;
1,3-bis(3,4-dicarhoxyphenoxy~benzene dianhydride;
1,4-bis~3,4-dicarboxyphenoxy~benzene dianhydride;
4,4'-bis(3,4-dicarboxyphenoxy)benzophenone
dianhydrides
: 4,(2,3-dicarboxyphenoxy~-4'-(3,4-dicarboxphenoxy)-
diphenyl_2,2-propane dianhydride; etc.,
and mixtures of such dianhydrides
Additional aromatic bis(ether anhydride)s also included
by Formula IV are shown by Koton, M.M : ~lorinski, F S.,
Bessonov, M.I.; Ruda]sov, A.P. (Institute of Heteroorganic
Compounds~ Academy of Sciences, U S.S R ) , U.S~S R.
257,010, Novemker 11, 1969~ Appl. May 3, 1967~ and by M.M.
. Koton, F.S. Florinski, Zh Org. Khin, 4 t5), 774 (1968).
The organic diamines of Formula V include, for example,
~- m-phenylenediamine,
p-phenylenediamine,
4~4'-diaminodiphenylpropane,
; 4,4'-diaminodiphenylmethane,
benzidine,
4,4'-diaminodiphenyl sulfide,
4,4'_diaminodiphenyl sulfo~é~
434'-diaminodiphenyl ether,
1,5-diaminonaphthalene,
3,3'-dimethylbenzidine,
3,3'-dimethoxybenzidine,
2,4-bis(B -amino-t-butyl)toluene~
bis(p- ~ -amino-t-butylphenyl)ether,
bis(p~ methylo-o-aminopentyl)benzene,
1,3-diam:ino-4-isopropylbenzene,
: .
- 6 -
. ; ~ : : ~
'~ ' .
~75~ ~
RD-7266
1~2-bis(3-aminopropoxy)ethane,
m-xylylenediamine,
p-xylylenediamine,
2,4-diamlnotoluene,
2,6-diaminotoluene,
bis(4-aminocyclohexyl)methane,
3-methylheptamethylenediamine,
4,4-dimethylheptamethylenediamine,
` 2,11-dodecanediamine,
2,2-dimethylpropylenediamine,
octamethylenediamine,
3-methoxyhexamethylenediamine,
2,5-dimethylhexamethylenediamine,
2,5-dimethylheptamethylenediamine,
3-methylheptamethylenediamineS
` 5-methylnonamethylenediamine,
1,4-cyclohexanediamine,
1~12-octadecanediamine3 ~ '!
bis(3-aminopropyl~sulfide, -
N-methyl-bis(3-aminopropyl)amine
hexamethylenediamine,
: hepta~ethylen.edi~mine, .
nonamethylenediamine,
decamethylenediamine,
bis(3-aminopropyl)tetramethyldisiloxane,
bis(4-aminobutyl)tetramethyldisiloxane, etc.
: and mixtures of such diamines.
- The phenolic resins of the C units of Formula I,
` herein and in the appended claims, comprise phenolic com-
pounds commonl.y referred to by those skilled in the art as
oil soluble thermoplastic phenolic resins prepared from the
. ~ .
''
::, ~ - .
- ,
- ,
.. ,: . - . . . .
RD-7266
75~
reaction of phenols and aldehydes under acidic or basic
catalyzed reaction conditions.
In general, the acidic catalyzed phenolic resins
are commonly referred to as "novolac" resins, i.e. resins
prepared under conditions which employ less than one mole of
aldehyde per mole of phenol. In general, the phenol reactants
are preferably bifunctional reactants, i.e. phenols that are
- substituted in an ortho or para position which polymerize to
form substantially linear phenolic resins that contain from 2
-; 10 to 20 phenol rings or more. In general, the phenolic resins
described herein are limited to phenolic resins having an
average molecular weight in excess of 125-150. Preferably,
the molecular weight is within the range of from about 350 to
1,000, or even higher, for example 5,000 or more.
The phenolic resins which are employed in the
practice of this invention are well-known to those skilled in
the art. Methods for their preparation and characterization
`~ are also well-known and are set out in various well-known
publications, e.g. Encyclopedia of Polymer Science 10, pages
1-73, entitled Phenolic Resins and The Chemistry of Phenolic
Resins by R.W. Martin, copyrighted 1956, published by John
Wiley and Sons, Inc., Library of Congress Catalog, Card No.
56-5711, as well as in numerous U.S. patents and other
.: .
; 8
~.
:
5~ ~
RD-7266
literature sources described and recited in the aforementloned
reference publications.
In theory, not intendld to limit thls invention in
any way, a highly idealized novolac resin molecule -- made
by the condensation o phenol with formaldehyde wherein the
resin is phenol-ended --- is illustrated by the following
formula wherein the phenolic nuclei are joined by methylene
bridges located ortho and para to phenolic hydroxyl groups:
OH CH2 ~ OH
CH2
In general, commercial oil soluble thermoplastic
phenolic resins are almost invariably prepared with acidic
catalysts, however oil soluble thermoplastic phenolic resins
prepared under noncatalyzed or even base catalyzed reaction
conditions can also b~ employed in this lnvention. The
phenols most commonly employed are phenol, resorcinol, and
alkyl-substituted phenols, e.g. cresols, xylenols, para-
tertiary-butylphenol, paxa-~ertiary-amylphenol, para-phenyl-
phenol, etc. The aldehyde most commonly employed is fonm-
aldehyde, almost exclusively, although small amounts o
acetaldehyde and furfuraldehyde can also be used. As is
well-known to those skilled in the art, formaldehyde is some-
times used in the form of its polymer, paraform, as a dry
:'
- g _
. .
:
':
,
7 ~
RD-7Z66
powder. In the practlce of ~his invention, preferably, the
phenolic resins have a melting point range of from about 40
to about 200 C., more preferably from about 60 to about
; 125 C.
In ~ preferred embodiment of this invention9 it is
preferred that the phenolic resins be prepared substantially
from phenols having para substituentsg more preferably
tertiary acyclic or cyclic hydrocarbon groups, i~e., groups
free of hydrogen atoms associated with the carbon atom direct-
ly bonded to a ring carbon atom, e.g. tertiary alkyl or
tertiary alkylene substituents even more preferably having
from 4 to 30 carbon atoms, such tertiary butyl, tertiary amyl
groups, etc. In addition to the novolac resins described
hereinbefore which are permanently soluble and cure only
upon the addition of a curing agent~ it is to be understood
that the phenolic resins employed in the practice of this
invention, altXough lEss~`preferred than the noYolac resins,
can be "resole" resins, i.e. resins prepared under conditions.
which employ more than one mole of aldehyde per mole of
~0 phenol, subject to the proviso that the resole resins employed
have limited amounts of reactive methylol -CH20H groupsO In
general, the resole resins that can be employed in the
practice of this invention can have a methylol content, on a
weight basis, o less than about 10 %, preferably less than
about 5 % and even more preferably less than about
.
10 _
- . .
~5~46
RD-7266
: 1 % b2sed on tot81 weight of t:he phenolic resins, since
phenolic resins which possess reactive methylol groups are
heat reactive, i.e. are capzble of being cured by the appli-
cation of heat and acids, which cure results from the
. ~
: 5 condensa~ion of the methanol ~roups associated with the
phenolic moie~y.
~'
.,
'`
' .
!"-,.. ` -- ' .... ....
. ;~, ' :.: '
'- ~:
: .: . '
1 ,
;''''
' ' ' ' : '
' ~ ',
. . '
'
~' " . ' ,' . '. '
RD-7266
~758~6
The resins of the C unitq of Fo~mula I compxise epoxy
compounds posseccing at least two 1,2-epoxide group, i.e., a
--C--C--
group. These polyepoxides may be saturated or unsaturated
aliphatic, cycloaliphatic, aromatic or heterocyclic and may
be substituted if desired with noninterfering substituents,
such as halogen atoms, phosphorus atoms, hydroxyl groups~
ether radicals, and the like. They may also be monomeric
or polymeric.
For clarity, many of the polyepoxides and particularly
those of the polymeric type are describf~d in terms of epoxy
equivalent values. The meaning of this expression will be
known to those skilled in the ar, and is specifically
described in U.S. patent 2,633,458 dated March 31, 1953.
The polyepoxides used in this invention are those having an
epoxy equivalency within the range of from about 0.8 to
about 1.8 or even higher.
- 20 Various examples of polyepoxides that may be used in
this invention are given in the aforementioned U.S patent
No 2,633,458 dated March 31, 1953 and it is to be understood
that so much of the disclosure of that patent relative to
examples of polyepoxides and methos for their preparation
will be applicable herein. An example of these polyepoxides
include diglycidyl ethers of bisphenol-A (DGEBA), i~e., an
epoxy resin of thf~ general formula
-- 1 2
' ' ' ' ": . '' .
~7~ R~-7266
O c~3 OH
CH2-CH-CH2 -O--- ~ C ~ OCH2--CH-CH2~
C~
/
/ CN3 0
, ~ OC~I2-CH-CH2
CH3
: 10 wherein n is an integer having an average value o~ ~rom about
0.2 to about 10. Other examples of epoxy resins include the
glycidyl e-thers of novolac resins, i.e., phenol-aldehyde
condensates~ Preferred resins of this type are those of the
formula
'` '~ ~ O-C-C/-~ O-C-C/ \C O-C--C/ \C
R ~ C~2 ~ CE2
~: n
: 20 wherein R is hydrogen or an alkyl radical and n is an integer
of 1 to about 10 Preparation of these polyepoxides i9 ',
` illustrated in U S. Patent 2,216,099 dated September 24,1940
::~ and U.S~ Patent No. 2,658,885 dated NovemberO 10, 19530
- ~ ~ e~ ld~
- ~ L~J Still other examples include the cpo~i~ic~ esters o~
the polyethylenically unsaturated monocarboxy~ic acids,
. . .~
such as epoxidized linseed~ soybean, perilla~ oiticica, tung,
walnut and dehydrated castor oil, methyl linolea~e, butyl
:. linoleate, ethyl 9,12-octadecandienoate, butyl, 9, 12, 15-
octadecatrienoate, butyl oleostearate, mono or diglycerides
`~ 30 of tung oil, fatty acids, monoglycerides of soybean oil,
sunflower, rapeseed7 hempseed, sardine, cottonseed oil~ and
; ; the like.
:. _ 13 _
;
.
RD-7 2 6 6
~(~'7~846
Another group oE the epoxy-containin~ material~ that
can be used in this invention include the epoxidizecl e~ters
of unsaturated monohydric alcohol~ and polycarboxylic acids,
such as, for example, diglycidyl phthalate, diglycidyl
adipate, diglycidyl isophthalate, di(2,3-epoxybutylladipate,
dit2,3-epoxybutyl)oxalate, di(293-epoxyhyexyl~ succinate,
di(3,4-epoxybutyl)maleate, di(2,3-epoxyoctyl)pimelate, di(2,
3-epoxybutyl)phthalate, di(2,3-epoxyoctyl3tetrahydrophthalate,
di(4J5-epoxydodecyl)maleate, di(2,3-epoxybutyl~terephthalate~
di(2,3-epoxypentyl)thiodipropionate, di(5,6-epoxytatradecyl)-
diphenyldicarboxylate, di~3,4-epoxyheptyl)sulfonyldibutyrate,
tri(2,3-epoxybutyl)1,2,4-butanetricarboxylate, di(5~6-epoxy-
pentadecyl)tartarate,di~4,5-epoxytetradecyl)maleate,di(2,3_
epoxybutyl)azelate, di(3,4-epoxybutyl)citrate, di(5,6-epoxy-
octyl)cyclohexane-1,3-dicarboxylate, di~4,5-epoxyoctadecyl)-
malonate.
Another group of the epoxy-containing materials include
those epoxidi~ed esters of unsaturated alcohols and un-
saturated carboxylic acids, such as glycidyl glycidate, 2,3_
epoxybutyl 3,4-epoxypentanoate: 3,4-epoxy-hexyl~ 3,4-epoxy-
` pentanoate; 3,4-epoxycyclohexyl 394~epoxycyclohexyl methyl
epoxycyclohexane carboxylate.
Still another group of the epoxy-containing material~
include epoxidized derivatives o~ polyethylenically unsatu-
rated polycarboxylic acids, such as, for example, dimethyl
8,9,12,13-diepoxyeicosanedioate: dibutyl 7,8,11,12-diepoxy-
~; octadecanedioate; dioct~l 10,11-diethyl-8,9712gl3-diepoxy-
eicosanedioat:e: dihexyl 6,7310,11-diepoxyhexadecanedioate:
; didecyl 9-epoxyethyl-10,11-epoxyoetadecandecanedioate;
dibutyl 3-but:yl-3,4,5,6-diepoxycyclohexane-1,2-dicarboxylate;
dicyclohexyl 3,4,5,6-diepoxycyclohexane-192-dicarboxylate;
dibenzyl 1, 2J4,5-diepoxycyclohexane-1,2-dicarboxylate and
-- 1 4 --
.''. . '~, ~ ,.
-
~ 84~ RD-7266
diethyl 5,6,10911-diepoxyoctadecyl succinate
Still another group comprises the epoxidized poly-
esters obtained by reacting an un~aturated polyhydric and/
or unsaturated polycarboxylic acid or anhydride groups, such
as, for example, the polyester obtainecl by reacting 8,9,12
13-eicosanedienedioic acid with ethylene glycol, the polyester
obtained by reacting diethylene glycol with 2-cyclohexene-
1,4-dicarboxylic acid and the like, and mixtures thereof.
Still another group comprises the epoxidized poly-
ethylenically unsaturated hydrocarbons, such as epoxidized
2,2-bis(2-cyclohexenyl)propane, epoxidized vinyl cyclohexene
and epoxidized dimer of cyclopentadiene.
The epoxy resins employed in the practice of this
invention, although belonging broadly to the class of epoxy
compounds descri~ed hereinbefore are limited to polyepoxy
resins having an epoxide equivalent weight in excess of 70.
Preferably, the polyepoxide equivalent weight is within the
range of rom about 450 to about 1,000, or even higher, for
example 5,000 or more For clarity, polyepoxides are de-
fined herein and in the appended claims in terms of their
epoxide equivalent weight. The term epoxide "equivalent
weight" refers to the weight of the epoxy reQin in grams
which contains one gram equivalent of epoxy.
In the preparation of the polyatheramide-imide co-
resin compositions of this invention which are solventless-
dry powder coatings, it is essential that the coatings be
prepared from blends that are homogeneous. In general~
the polyetheramide-imide and the coreqin are combinable
with each other in all proportions~ Howevex, in the use
of the compositions o~ tbis invention in the manu~acture
of electrical insulation systemæ ~or motors, coil or magnet
wires (wire for magnetic coils), etc., it is preferred that
.;
::
RD-7266
~.07~8~L6
the compositions contain at least 4~/0 by weight polyeth-
eramide-imide and preferably more often at least 75%
polyetheramide-imide because of the outstanding electrical
properties contributed by the polyetheramide-imide com-
pound of solvent-ree PEAI-coresin compositions,
In general, the polyetheramide-imide coresin blends
of this invention in pulverulent form are particularly
suited to the continuous coating of wire su~strates em-
ploying fluidized bed coating 1:echniques, They are especially
useful in fluidized bed coating methods which coat wire
substrate by passing the wire through a cloud of elect-
rostatically charged particles of polyetheramide-imide co-
resins suspended above the upper surface of a fluidized
bed of a PEAI- co-resin powder contained within a coating
chamber, Subsequent passage of the electrostatically coated
wire to another chamber at temperatures elevated from that
' of the coating chamber wherein the polyetheramide-imide
co-resins are sintered, flowed, leveled and cured into the
uni~orm coating essentially free of voids - provides ex-
cellent insulated wire coating,
In general, in the solventless-dry powder coating
applications employing the novel compositions of this
invention~ the following powder characterizations are gen-
erally found to be deæirable - - and often essential - - to
the economic utilization of the resin b~ends of this in-
vention, In brief, the suitability of the polyetheramide-
- imide co-resin compositions to solventless-dry powder
coating requires consideration o~ the following factors:
Average Particle Size (APS)
Sintering Temperature Range (STR)
Viscous Flow Temperature Range (VFTR)
;~ Leveling Temperature Range (LTR)
:: Optimum Cure Time and Temperature Range (OCTTR)
With regard to Particle Size, as used herein and in
_ 16 _
:
~7584~ RD-7266
the appended claims, the resin powders when employed in
insulating wire proces~e~ generally comprise particles
having a diameter or fro~ about S to about 200 microns (~f)
and preferably from 5 to 60 microns for coatings up to 3
mils in thickness.
With regard to Sintering Temperature Ranges~ as used
herein in the apppended claims, the resin powder sintering
temperatures are defined as the lowest temperature in degress
centigrade (C.) at which solvent-free polyetheramideimide
co-resin powders - - hereinafter sometimes referred to for
brevity as resin powders - - having the particle size
limitations set out hereinbefore show adherence to themselves
and to a substrate, but sho no significant viscous flow or
leveling In general, the "STR' for solventless-dry powder
coatings are within the range of from about 75 to about
200 , preferably from about 140 to about 190 C In general~
the "STR" of any resin powder can be readily determined and
- reproduced within i 5 C. accuracy by simple laboratory
procedures described elsewhere in this specification.
With regard to ~iscous Flow Temperature Range, as used
herein and in the appended claims, viscous flow temperatures
` are defined as the lowest temperature in dPgress centigrade
( C ) at which individual polymer particles lose all angula-
rity and show a rounded or uniform curved surface at the air-
interface - - usually resembling a hemispherical droplet
with the largest cross-section at a substratemelt interface.
The viscosity of the melt of the resin powders within the
"VFTR" is in the ordex of 10 to 10 poise at zero or low
shear (0.025 sec. ) In general, the polymer powders
heated at the viscous flow temperature will form a film but
will not necessarily flow out to form a completely smooth
surface.
- 17 -
107 5~4~ RD-7Z66
In general, the xesin powder which exhibits viscous
Elow, as defined abovel is suitable for production of coatings
of thickness grea-ter than about 2 mils. A resin powder which
becomes fluid enough to show "leveling" b~fore cure is well-
adapted for production of high quality thin-film coatings in
the order of 1 to 2 mils, as well as thicker films.
In general, the "VFTR" for solventless-dry powder coatings
o o
are within the range of from about 75 to 240 , preferably
from about 155 to about 220 C In general, the "VFTR" of
any resin powder can also be readily determined and re~
produced within ~ 5C. accuracy by simply laboratory proced-
ures also described else~here in this specification.
With regard to the Leveling ~emperature Range, as uæed
herein and in the appended claims, "LTR" i5 defined as the
lowest temperature at which a resin powder flows and flattens
to give a thin film with a glossy surface wherein a group
of resin particles coalesce to form a flat upper surface
and exhibit an obvious curvature at the contact angle sur-
rounding a periphery of a coalesced resin powder.
In general, the "LTR" for solventless dry powder coat-
ings are within the range of from about 160 C to 280 C ,
preferably fr~m 200 ~ In general, the "LTR" of any resin
powder can also be raadily determined and reproduced with
+ 10 C accuracy by simply laboratory procedures also
described elsewhere in this specification.
- In general as defind above, resin powders which exhibitaverage particle size, sintering temperature range~ viscous
flow temperatuxe, and leveling temperature characteristic
are suitable solventless-dry powder insulating coating mat-
erials.
Summarily, finely dividad resin powders as characterized
hereinbefore coalesce at temperatures below the melting point
'
; - 18 _
:;.
` ` : ~. .
D-7 2 6 6
of the polyetheramide-imide resin component o~ the resin
powders and cure into solid, homogeneous cured coating~
under the influence of heat and in the absenca of pre~ureO
In general, any method well known to tho~e skilled in
the art can be employed in the preparation o~ the homogeneous
resin powders of this invention, including the preparation
of a homogeneous admixture of pc>lyetheramide-imid~ resins
and phenolic or epoxy resins employing either solution or
melt mixing techniques for the preparation of a homogeneous
uniform mixture. In general, homogeneous uni~orm admixtures
mixture. In general, homogeneous uniform admixtures can be
prepared by dissolving the polyetheramide-imide resin and
t~e solid co-resin in a suitable solvent such as ketra-
hydrofuran, dichlorobenzene, m-cresol, toluene, formamide,
N-methylpyrrolidona, dioxane/ortho-dichlorobenzene toluene
mixtures, N,N-dLmethylformamid2, etc., in which to affect a
ture solution between the polyetheramide-imide and phenolic
resins, at temperatures of from about 25 to about 100 C
The homogeneous solutions can be spray-dried to form polymer
resins of the desired particulate size, or alternatively
the homogeneous blend of polymers can be precipitated from
the solvent by using a suitable non~olvent such as w~ter or
hex~ne in which to affect precipitation of the homogeneous
blend of resins having a suitable particle size after drying
and grinding by any suitable means. Alternatively, the
polyetheramide-imides and the liquid or solid co-resin can
be melt blended and extruded with concurrent mixing at
elevated temperatures, e.g within the temperature range of
from about 170 to about 350 C The resulting extrudate can
be prepared in a particulate form by any suitable method
such as grinding, spray drying, precipitation ~rom non-
solvents, etc
_ 19 _
RD-7266
-~7~
In addition to the polyetheramide-imide resin and
phenolic resin components of the resin powders9 other
ingr~dients can be included in the resin powders which in-
clusion may assist in providing solvent-free polymer powders
that sinter, flow, level and cure into coherent films - -
other fillers which are nondelel:ericus to the characteristics
of electrical insulating resin E)owders can also be included,
e.y. nonmetallic fillers, such clS particulate polytetra-
fluoroethylene resin, asbestos, clay, mica? vermiculite,
kaolin, fumed silicas, titanium dioxide and other optional
fillers or ingredients, e.g. plasticizers, flexibilizers,
stabiliæers, surfactant agents, pigments, dyes, rein-
~orcements, flame retardants, diluents, and mixtures thereof,
etc In nonelectrical applications, fillers which are often
deleterious to the characteristics of electrical insulating
resin powders can also be include, e.g. silicon caxbide,
molybdenum disulfide, cryolite, boron nitxide, iron sulfide,
metal carbides, metal oxides, carbon fibers, graphite,
powdered metals such as aluminum, copper and the like. In
addition to the other fillers ox ingxedients noted hexein-
before3 conventional curing agents fox phenolic resins well-
known to those skilled in the art which enhance certain pro-
perties of the resin powders, e.g. cut-through temperatures,
may be used if desired. Where a polyepoxy resin comprises
the co-resin of this invention, the resin powders may
contain low molecular weight monoepoxides wherein said mono-
epoxides comprises no moxe than l~o by weight of the poly-
epoxides content of the resin powders. The monoepoxides may
be aliphatic or cycloaliphatic ox heterocyclic and may be
saturated or unsaturated and may be substituted with aromatic
rings, ether groups, halogen atoms, ester groups and the like.
Examples of suitable monoepoxides include, among others,
_ 20 _
,
RD-7266
7~8~6
styrene oxide~ phenyl glycidyl ether, allyl glycidyl ether,
ocatadecyl glycidyl ether, amyl glycidyl ether, tolyl gly-
cidyl ether, diacetate o monoglycidyl ether of glycerol,
dipropionate of the monoglycidyl ether of glycerol, dia-
crylate of the monoglycidyl ether of glycerol, 1,2-hexylene
oxide, ethylene oxide, propylene oxide 9 l-heptylene oxide,
3-ethyl-1,2-pentylene oxide, glycidyl acetatel glycidyl
benzoate, glycidyl propionate, glycidyl arcylate, glycidyl
allyl phthalate, glycidyl methyl maleate, glycidyl stearate,
methyl 1,2-epoxypropionate, butyl 1,2-epoxypropionate, and
the like
The inclusion of the monoepoxide ingredients may be
of assistance in providing solvent-free polymer powders
that sinter, flow, level and cure into coher2nt films.
Fillers as above mentioned for the phenolic co-resin
blends may also be employed when the polyepoxide is the
co-resin. In addition to these other fillers or ingredients
conventional curing agents for epoxy resins well-known to
those skilled in the art which enhance certain properties of
the resin powders, e.g cut_through temperatures, may be
used if desired. Representative curing agents include boron
trifluoride and complexes of boron trifluoride with amines,
amides, ethers, phenols and the like, etc.
The following examples illustrate - - but do not limit
_ _ the best mode of practicing the invention to a person
skilled in the artO
Unless otherwise indicated in the examples, the follow-
ing procedures were employed in the preparation and testing
of the polymer powders of this invention Any deviations
from the general procedura is noted in ~he specific examples.
A series of resin powders were prepared employing
polyetheramide-imide resins - - characterized by dianhy~
RD-7266
1~75i3A~
dride and diamino reactants _ - having an in-trin~ic viscocity,
[~] 0 2-0.6 dl./gm. at 25 C., measured in chloroform or
N-methylpyrrolidone (NMP) depending upon the degree of imidi-
zation and a glass-transition t:emperature Tg of 140-225 C
The polyetheramide-imide resins were prepared in accordance
with the procedures described in the a~orementioned U S
patent 3~850,885 dated November 26, 1974~
The phenolic resins employed in the preparation of
the resin powders were commercially available materials,
e.g., Union Carbide Company's CKM_2103, an oil-soluable
novolac resin prepared from a para-tertiary-butylphenol and
formaldehyde having a softening point within the range of
from about 100 to 120 C. (215-245 F ) and a specific
gravity range of 1.06 to 1.08: CKM-0036, a novolac resin
B prepared from a para-tertiary-amylphenol and dorm~l~ehy
having a softening point of range of from 85 to 100C.
~l85-2looF~ and a specific gravity range of 1.04 to 1.06;
CKM_1282, a resole phenolic resin prepared from the re-
action of paratertiary-butylphenol and formaldehyde having a
2~ so~tening point range of from 82 to 100 C (180-210 F.) and
a specific gravity range of 1.10 to 1.12; CKM-1634, an oil-
soluble resole resin having a softening point range of from
88 to 105 C. (190-220 F.) and a specific gravity range of
1.09 to 1~11, and CKM-1636, an oil-soluble resole resin
having a softening point range of from 105 to 127 C (220-
260 F.) and a specific gravity range of 1.09 to 1.11.
m e epoxy resins employed in the preparation of the
resin powders were commercially available materials, e.g.,
Ciba Products Co 's EC ~1280, a polyglycidyl ether of orth_
ocresol formaldehyde novolac having a molecular weight of
about 230, and Durrans~ melting point of about 78-81 C ;
DOW Chemical Co.'s DER 332, 661 and 741, diglycidyl ethers
- 2 2 -
;: ~
- :
RD-7266
-~75~4~
of biqphenol-A, an epoxide equivalent weight o~ 175$525,
370, respectively~ and DER 732 and 736, diglycidyls ethers
of propylene glycol having an epoxide Pquivalent weight of
about 320, 190, respectively, DEN~4399 an epoxy novolac
resin having an epoxide equivalent weight of about 200:
and Shell Chemical Co '~ EPON ( ) 828 and 1004 having an
epoxide equivalent weight of about 190, 925, respectively.
The sintering, vi~cous flow, and levelling tempera-
tures for the resin powders were determined according to the
following test sequence. A series of s~lvent-free powder
portions having an average particle size o~ 200 microns
or less (0.1 to 0.5 mg.) were sprinkled onto preheated glass
slides resting on temperature gradient blocks at temperature
intervals of about 5 C. over a temperature range of from
about 130 to about 250 C. After 5 minutes, the glass slides
were removed from each temperature gradient block position,
allowed to cool at room temperature and the polymer particles
were examined with a stereoscopic microscope at 45X magnifi-
cation The temperatures at which the polymer particles
reached their sintering temperature~ viscous flow temperature
or leveling temperature as defined elsewhere in this specifi-
cation were recorded.
Various resin powders in addition to being evaluated
under sintering, viscous flow, and leveling characteriza-
tion were also evaluated for cut-through temperature, dis-
sipation factor, initial flexibility after cure, and thermal
flexibility li~e according to the following test procedures.
Unsupported films of resin powders having a uniform
thickness of less than about 3 mils were prepared and were
cured, generally, for 15 to 30 minutes at 300 CO
me cured films were tested by placing a small piece
of the cured film between two bare copper wires crossed at
~ r~
!
1075B4~ RD-7266
a 90 angle in a cut-through apparatus commonly employed by
the electrical industry in the evaluation of enameled magnet
wire J A N -W-583 (7 April 1948). The copper wires were
electrically insulated Erom a metal plate by 5 mil mica sheet.
The cut-through temperature of the cured film was determined
by placing the test apparatus in an air circulating oven with
the copper wires connected to 110 volt AC circuit which con-
tained an alarm system A 1000 gram load was placed on the
upper copper wire - crossed wire pair. The loaded film rest-
ing between the crossed wires was heated in an air circulatingoven at a rate of about 10 C per minute and the temperature
was recorded at which the film flowed enough to permit elect-
rical contact between the wires, thus activating the alarm
system
Cured resin powders in the form of films wer0 tested
for the property described as dielectric dissipation factor
which is defined heræin as the "dielectric dis~ipation factor,
loss tangent" and which is related to the heat produced in an
electrically insulating material under imposed voltage. The
electrical insulating quality of a film is dependent on its
ability to retain a low dissipation factor at the maximum
temperature of use.
The tests were performed accordingly. Cured resin powder
film was clamped between two circular brass discs of 1.25"
diameter which serves as electrodes. The film with attached
electrodes was immersed in a number 10 C Transformer Oil and
the dissipation ~actor was reader on a capacitance test bridge
of standard type capable of measuring directly the dissipa-
tion factor of a film in the range from 0 0.5 at 60 hertz.
The oil was slowly raised in temperature and additional dis-
sipation factor values were measured at a series of temperatures
between 120 and 220 ~
. ~
_ 24 -
, ' ~ '
~7 5~4~ RD-7266
Flexibility of cured resin powder film w~s determined
by a simple 180 bend test accordingly, Cured resin films
of 3 mil thickness were tested for acceptable flexibility
by a test described as "bend and crease" in which a film i9
folded over on itself to a 180 angle and the fold is then
creased by normal pressure from the fingers, A film is con-
sidered to have adequate flexibility if it does not crack or
break into two pieces in this test,
Cured resin films were measured for their resistance
toward embrittlement at 300 C, Strips of 3 mil film were
heated in an air circulating oven maintained at 300 C, The
films were withdrawn periodically and cooled to room tem-
perature and thsn tested for flexibility by the above-
mentioned bend and crease test, By this procedura the~app-
roximate time at 300 C, required to proceduce enough em-
brittlement so that the thermally aged film would breaX into
two pieces in the hend and crease test was determined and
recorded,
EXAMPLE I
This example illustrates the reduction in the sinter,
viscous flow and leveling properties of polyethexamide-
imide phenolic resins which are suitable for dry powder coat-
ing applications, Set out in Table I hereafter is a summ-
ary of the proportions by weight of anhydride-capped poly-
etheramide-imide resin an~ phenolic resin) the sintering
temperature, the siscous flow temperature and the leveling
temperature of the various blends,
- 25 -
~D758'~
RD-7266
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RD-7266
3~)7S846
EXAMPLE I a
This example illustrate~ the reduction in the sinter,
viscous flow and leveling properties of polyether-amide-imide
epoxy resins which are suitable for dry powder coating
applications Set out in Table Ia hereafter is a summary of
the proportions by weight of polyetheramide-imide resin and
polyepoxy resin, the sintering temperature, the viscous flow
temperature and the leveling tempQrature of the various
blends.
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RD- 7 266
As illustrated by the above examples, the sinter,
viscous flow,and leveling characteristics, primarily the
viscous flow and sinter characteristics of the polymer
powders are significantly decreased in value 3S the amount of
co-resin increases in relationship to the amount of
anhydride-capped polyetheramide-imide resin contained in the
combination.
EXAMPLE II
This example illustrates the reduction in the
sinter, viscous flow and levelin~ propertles of polyether
~; amide-imide phenolic resins which are suitable for dry
- powder coating applications. Set out in Table ~ hereafter is
a summary of the proportions by weight of amine-capped
polyetheramide-imide resin and phenolic resin, t~e sintering
temperature, the viscous flow temperature and the leveling
: temperature of the various blends.
'~'
:
. . ............................. . .
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:~ , . . . .~ - .
. , . . - :
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.
.. .
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1~7S3 3~; RD-7266
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(D N ~r::: ~ N N ~ N
N ~ ~ N N N N 11')
~ Ul OOU~OU~ U~OOOO
h ::1 o N ~ ~ (~ I` O N ~r) N ~1
~ O N N N N N ~I N N N N ~N
~ ~1 n o u~ o o o o u~ o u~ S
.. ~ i` CD cn O N~ ) O H
U~ ~ ~1 ~I N N --I H -1 N N ::~ N
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H ~ ~ N N N N N ~ ~ H U
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75~
RD-7266
As illustrated by the above examples, the sinter,
viscous flow and leveling characteristics, prirnarily the
viscous flow and sinter characteristics of the polymer
powders are significantly decreased in value as the amount of
phenolic resin increases in relationship to the amount of
amine-capped polyetheramide-imide resin contained in the
combinations.
EXAMPLE III
A solution of 22.90 g. (.044 mol) of 2,2-bis[4-
~3,4-dicarboxyphenoxy)phenyl] propane dianhydride (4-BPADA)
in 200 ml. of tetrahydrofuran (THF) was treated dropwise with
7.93 g. (.040 mol) of methylene dianiline (MDA) in 100 ml. of
THF with stirring. After complete addition and stirring for
an additional hour, 10.28 g. of CKM 2103 was added and the
THF removed thermally to yield a powder which when cured as a
- film gave excellent flexibility and a cut-through temperature
of 280 C.
EXAMPLE IV
A series of polyetheramide=imide phenolic resin
20 blends were prepared and the resulting properties of the
resulting resin powders ater formation into cured films were
characterized, as set out in Table III, according to cut-
through temperature C~, dissipation factor at 220 C~,
and initial flexibilit~.
:.,
10 7S84t~ RD- 7 266
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RD-7266
~L~75~
Resin powders of the compositions and charaeteris-
tics of this example having an average particle size of from
5 to 60 microns can be employed in solventless-dry powder
fluid bed electrostatic coating and curing of PEAI-phenolic
resins onto wire substrates to readily form insulated wire
thiekness having a continuous film oE from 0.~-10 mils
(radial thickness) and from 1.0~20 mils (diametric thickness)
in wire coating process apparatuses employing fluidized bed
"~ electrostatic coating and thermal fusion and curing of the
polymer particles at wire speeds of from 1 to 60 feet per
-~ minute employing round, rectangular, or strip wire of any
thickness. Wire insula-tion of eonventional film thicknesses,
prepared accordingly, when tested at suitable voltage
- differentials for the deteetion of pinholes (voids in the
eured coating which permit the flow of eurrent from an
energy souree loeated on the surfaee of eoating through the
wire to ground) have the minimum pinhole loeations suited to
high eleetrieal integrity insulation.
EXAMPLE V
A soluticn of 22.90 g. (.044 mol) of 2,2-bis[4-
(3,4-diearboxyphenoxy)phenyl] propane dianhydride (4-spADA)
in 200 ml. of tetrahydrofuran (THF) was treated dropwise with
7.93 g. (.04 mol) of methylene dianiline (MDA)in 100 ml. of
~` THF in a one-necked l-liter round-bottomed flask equipped
- 33 -
~ O 7 5~4~ RD-7266
with magnetlc stirrer. After completing the addition of the
MDA, the mixture was stirred for an hour, the THF was
removed under vacuum and replaced with 600 ml. of a 50/50
mixture of toluene/chlorobenzene mixture. The flask was then
. .
equipped with a Dean Stark trap and condensor. The contents
of the flask were brought to reflux and the water of imidi-
zation removed over a 6-hour period by azeotropic distillation.
The toluene was removed by distillation and the chlorobenzene
solution was cooled. The polymer was precipitated in four
10 liters of methanol. The resulting PEAI white precipitate,
was collected and dried in a vacuum oven at 100 C. and
;
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RD-7266
~1.0758~6
exhibited an I,V, of 0,358 dl, /g, as measured in CHC13 and
0.375 dl./g, as measured in N-methyl pyrrolidone at 25C,
7,5 g, of the PEAL polymer was redissolved in methylene
chloride and 2,5 g, of CKM 2103 added, The solvent was re-
moved thermally to yield 10 g, of polyimide-phenolic blend,
The material sintered at 195C, and underwent viscous flow
at 235 C, When a melt-drawn film was cured at 3000C, for
1/2 ho~r, a cut-through temperature of 280 C, resulted.
EXAMPLE VI
80,41 ~ (,1545 mol) of 4-BPADA was placed in a Model
2CV-~e~ico~ Mixer made by Atlantic Research Corp, m e
mixer was heated to 545 F, with stirring and an inert gas
passing throu~h the bowl and 16,2 g, ( 0.15 mol) of m-
phenylenediamine was added over the period of 1,5 minutes,
After stirring for 60 minutes, the mixture was extruded out
to yield a polymer having an I,V. of 0.40 as measured in
CHC13 at 25 C. Subsequently, the polyetherimide w~s di~-
solved in chloroform with 30 g, of CKM 2103 and the solvent
was removed thermally to yield 120 g, of polyetherimide
phenolic blend, m e material sintered at 190 C, and under-
; went viscous ~low at 230C, When a melt-drawn film was
cured at 300 C, for 1/2 hours, a cut-through temperature of
305C, resulted. The results of this detailed example is
summarized in Table IV, Run A, m e resulr of other similarly
performed Runs, different from Run A with respect to the
amount of phenolic resin employed pluse a control Run, are
also set out in Table IV which follows:
_ 35-
RD-7266
~75846
TABLE IV
Run Phenolic BPADA:MPDA Weight Ratio Melt Character C
Nos. TypePBAI Type Phenolic:~EAI Sinter Viscous Leveling
ACKM 21033~c's BPADA 25:75 190 230 (3)
B " "15:85 195 ~235 "
C " "5:95 225 ~235 "
D none "0:100 225 ~235
(1) BPADA - same as in Example I, Table I
MPDA = m-phenylene diamine having the structural
formuLa:
NH
1 2
.
(2~ Intrinsic viscosity of the 3% excess BPADA polymer was
.040 dl./g. as measured in NMP at 25C~
(3) Cured before leveling
In commercial operations, most ~onveniently blending
and heating is carried out on a ~ixing extruder such as a
.. ~ .,
Werner-Pfleiderer Twin-Screw extruder. Alternatively, a
Bra~ender mixing bowl or Helicone mixer may be employed.
ExAMæLE YII -~
. .
A solutic~n of 20,82 g, (,0400 mol~ of 2~2-bis L4-(3,4-
dicarbox~phenoxy) pheny~ propane dianhydride (4-BPAD~) in
E~ 200 ml. of tetrahydrofuran $ ~ was added dropwise to 9.372
(,0473 mol) of methylene dia~iline (MDA) in 100 ml, of T~ in
a one-necked l-liter round-bottomed flask equipped with magnetic
stirrer. After completing the addition of the 4-BPA3A, the
mixture was stirred for an hour, the THF was removed under
vacuum and replaced with 600 ml. of a 50/50 micture of
toluene/chloroben2ene mixture. The flask was then equipp~d
with a Dean Stark trap and condensor. me contents of the
flask was brought to re~lux and the water of imidization re-
moved over a 6-hour period ~y azeotropic distillation. The
- 36 -
:. .
,
-~75~4~ RD-7266
toluene w~s removed by dis-tillation and the chloxobenzene
solution was cooled. The polymer was precipitated in four
liters of methanol. The resulting PEAI white precipitate
was then collected and dried in a vacuum oven at 100 C.
23 1 g. of the PEAI polymer was redissolved in meth-
ylene chloride and 5.76 g. of C~M 2103 added. The solvent
was removed thermally to yield 28.86 g. of polyimidephenolic
blend. The material sintered at 195 C and underwen~
viscous flow at 210C.
The resulting PEAI phenolic resin blend was ground in
a jet mill and sieved to yield powder with less than 53
particle size m e powder was coated at l5KV from an
electrostatic fluidiæed bed onto 2 mil aluminum foil and
cured for 5 min. at 275 C. The coating was well-fused, with
slightly rippled surface. A film having a 2 mil thickness
- could be bent and creased without cracking, and a 4 mil
thickness could be bent around a 50 8 ~il mandrel wi*hout
cracking. Dielectric breakdown for film thickness ranging
from 2-3 mils gave an average value of 1.7 KV.
Resin powders of the compositions and characteristics
of this example having an average particle~siæe of from 5
to 60 microns can be employed in solventless-dry powder
fluid bed electxostatic coating and curing of PEAI-phenolic
~- resins to wire substrates to readily form insulated wire
thickness having a continuous film o~ from 0.5-10 mils
~radial thickness) and from 1.0-20 mils (diametric thickness3
in wire coating process apparatuses employing fluidized bed
electrostatic coating and thermal curing of the polymer
-~ particles at wire speeds of from 1 to 60 feet per minute em-
~;~ 30 ploying round, rectangular, or strip wire of any thickness.
Wire insulation of conventional film thicknesses, prepared
accordingly, when tested at suitable voltage differentials for
~- _ 37_
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~7 5846 RD~7266
the detection of pinholes (voids in the cured coatings which
permit the flow of current from an energy source located on
the sur~ace of coating through the wire to ground) have the
minimum pinhole locations suited to high electrical in-
tegrity insulation.
EXAMPLE VI I I
This example illustrates that liquid epoxy resins may
be employed in the preparation of polyetheramide-imide epoxy
resins which are suitable for dry powder coating applications.
This is made possible by a concurrent blending and heating
operation of a polyetheramide-imide resin and epoxy resin
mixture in which the epoxy resin is lightly crosslinked or
B-staged to form a solid but fusible polyetheramide-imide
- epoxy resin~blend.
In this example the blending and heating o~ the PEAI and
liquid epoxy resin was performed on a laboratory scale using
a preheated glass slide on a temperature calibrated hot plate.
The solid polyetheramide-imide resin and the liquid poly-
epoxy resin were placed on the slide and mixed using a metal
spatule for the prescribed time.
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~7~84 RD-7266
In commercial operations, most conveniently blending
and heating is carried out on a mixing extruder such as
a Werner-Pfleiderer ~ Twin-Screw extruder. Alternatively,
a Bradender mixing bowl~ ~elicone @ mixer may be employed.
.i
. EXAMPLE IX
-,
~:~ A series of polyetheramide-imide epoxy resin blends
were prepared and the resulting properties of the resulting
resin powders after formation into cured films were charact-
erized according to cut-through temperature C., dissipation
: 10factor at 140 C.~ temperature at which dissipation factor
reached a value of 0.2, initial flexibility, and thermal
~lexibility life at 300C.
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~07 584~ RD_7266
Resin powders of the compositions and characteristics
of this example having an average particle size of from 5
to 60 microns can be employed in solventless-dry powder
fluid bed electrostatic coating and curing of PEAI-epoxy
resins onto wire substrates to readily form insulated wire
thickness having a continuous film of from 0.5-10 mils
~radial thickness) and from 1.0-20 mils (diametric thickness)
in wire coating process apparatuses employing fluidized bed
electrostatic coating and thermal fusion and curing of the
polymer particles at wire speeds of from 1 to 60 feet per
minute employing round, rectangular, or strip wire of any
thickness~ Wire insulation of conventional film thicknesses,
prepared accordingly, when tested at suitable voltage dif-
ferentials for the detection of pinholes ~voids in the
cured coating which permit the flow of current from an
energy source located on the surface of coating through
the wire to ground~ have the minimum pinhole locations
suited to high electrical integrity insulation.
EXAMPLE X
.
A solution of 22.90 g. t.044 mol) of 2,2-bis ~4-(3~4-
dicarboxyphenoxy)phenyl pxopane dianhydride (4-BPADA) in
200 ml. of tetrahydrofuran (THF) was treated dropwise with
7.93 g. (.04 mol) of methylene dianiline (MDA) in 100 ml.
of THF, in a one-necked l-liter round-bottomed flask equipped
with magnetic stirrer After complete addition and stirring
for an additional hour, the THF w~s removed under vacuum and
replaced with 600 ml. of a 50/50 mixtuxe of toluene/chloro-
... .
benzene mixture. The flasX was equipped with a Dean Stark
trap and conde!nsor. me contents of the flask were then
brought to reflux and the water of imidization removed over a
6-hour period by azeotropic distillation. rrhe ~ was
removed by distillation. m e resulting chlorobenzene sol~
:
107S84~i RD-7266
tion ~as cooled and the polymer was precipated in four liters
of methanol, A white precipitate was collected and dried in
a vacuum oven at 100 C. The polymer had an I.V. , 0,358 dl,/g,
as measured in CHC13 and 0,375 dl,/g, as measured in N-methyl
pyrrolidone at 25C,
7,5 g, of polymer was redissolved in methylene chloride
and 2.5 g. of DER 661 added. l~e solvent was removed the-
rmally to yield 10 g, of polyimide-epoxy blend~ The material
sintered at 170 C, 9 underwent viscous flow at 205 C, and
levelled at 235 C, When a melt-drawn film was cured at
300 C, for 1/2 hour a cut-through temperature of 215C.
resulted,
EXAMPLE XI
A solution of 22,90 g. (,044 mol) of 2,2-bis 4-(3g4_
dicarboxyphenoxy)phenyl propane dianhydride (4-BPADA) in
200 ml. of tetrahydrofuran (THF) was treated dropwise with
7,g3 g, (,040 mol) of methylene dianiline (MDA) in 100 ml,
of THF with stirring, After complete addition and stirr-
ing for an additional hour, 10,28 g, of EPON 1004 was added
and the THF removed thermally to yield a pol~mer which when
:~ cured as a film was excellent flexibility and a cut-thru
temperature of 225C.
EXAMPLE XII
80.41 g, (,1545 mol) of 4-BPADA was placed in a Model
2CV Helicone Mixer made by Atlantic Research Corp, The
mixer was heated to 545 F, with stirring and an inert gas
passing through the bowl and 16,2 g, (0,15 mol) of m-
phenylenediamine was added over the period of 1.5 minutes,
After stirring for 60 minutes~ the mixture was extruder
out to yield a polymer with I.V. = 0,40 as measured in
CHC13 at 25C, Subsequently, 90 g, of the polyimide was
dissolved in chloroform with 30 g, of DER 661 and the solvent
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E~MPLE XIII
.
A solution of 22,90 g, (,044 mol) of 2,2-bis 4-(3,4-
dicarboxyphenoxy)phenyl propane dianhydride (4~BP~DA) in
200 ml, of tetrahydrofuran ~T~) was treated dropwise with
7,93 g, (,04 mol) of methylene dianiline (MDA) in 100 ml,
of THF, in a one-necked l-liter round-bottomed flasX equipped
with magnetic stirrer. After complete addition and stirr-
ing for an additional hour, the THF was removed under vacuum
and replaced with 600 ml, of a 50/50 mixture of toluene/
chlorobenzene, and the flask equipped with a Dean Strak
trap and condenser, The contents of the flask were then
brought to reflux and the water of imidization removed over
a 6-hour period by azeotropic distillation, The toluene was
; then removed by distillation and the chlorobenzene solution
was coolad and the polymer subsequently precipitated in our
liters of methanol, m e shite precipitate was then collected
and dried in a vacuum oven at 100 C,I.V. dl/g, = 0,358 in
CHCH13 and 0.375 in ~-methyl pyrrolidone,
25 g~ of polymer was redissolved in chloroform and 25
g, of DER 661 added, The solvent was removed thermally to
yleld 50 g, of polyimide-epoxy blend, The material sintered
at less than 140 C., underwent viscous flow at 145C, and
leveled at 200C.
me polymer was ground, sieved to less than 53
;~ particle size, and was then coated onto aluminum strip from
an electrostatic fluid bed operating at 15 KV, The powder-
coated strips were heated for 5 minutes at 250 C,, followed
by 5 minutes at 275C, and either 10 minutes or 20 minutes
.: o
at 300 C, Cured ~ilms were smooth and glossy3 ranging ~rom
; 3 to 4 mils :in thi~kness, Dielectric breakdown tests gave
values of at least 6KV, and 2~3 of the tests gave values
greater than 7KV, Cut-through tempe~atures for film cured
10 minutes at 300C, were 215 C,; all samples had excellent
_ 46 -
~ 7584~ RD_7266
flexibility
The powdered partlcles which can be prepared from the
compositions of this illvention are particularly adapted
for use in electrostatic powder spraying equipment~ fluidized
resin bed coating processes as well as fluidized resin bed
coating processes which employ electrostatic transfer methods
for the coating of any article. In genera]., in a preferred
embodiment of this invention, the solventless-dry powder
resins are used in a fluidiæed bed coating process where a
wire is passed through the fluidized resin bed containing a
bath of fluidized powder having an electric potential dif-
ferent from that of the wire to be coated, such that the
charged polymer powder particles are attracted and secured
as a uniform layer over the surface of the wire. The
uniformly coated wire is thereafter passed into a heating
zone where the powdered particles are melted, flow out over
the wire and cure to form a smooth and uniform cured film
of resin on the wire
In general, in addition to the above wire insulating
processes~ the compositions of this invention can also be
employed in other wire insulating processes employing other
coating processes, e.g. where the wire substrates to be
coated is preheated to a temperature within the sintering,
viscous flow and leveling temperature of the resin powdexs
causing adherence of the powder particles to the wire with
subsequent withdrawal from the coating area, e.g. a
fluidized bath, with subsequent passage to a heating æone,
e.g. a curing tower, to form a smooth~ continuous, uniform
film cured wire insulation film over the surface of the wire.
The resin powders of this invention in general have the
desired powder characteristics required, i e. particle size,
charge acquisition, charge retention, melt flow, surface
- - 47 -
?
107 5~46 RD-7266
tension, wetting properties, which permit powder coating of
metallic conductors at temperatures of 20 to 300 C or
even higher, and which on subsequent heating to temperatures
above 200 C., e.g. temperatures of from about 250 to 400~
provide insulating coatings which meet the thermal, elect_
rical and mechanical insulation requirements for wire
coating films, e.g. coating films of from l to 30 mils, or
even thicker.
Although the preferred use of the compositions of this
invention is solventless-dry powder coating and curing of
; insulating films on various substrates, it is to be under-
stood that the resin powders can be molded using techniques
conventionally employed in molding powdered metals such as
by sintering or hot pressin~; see for example "Encyclopedia
of Chemical Technology" edited by Kirk and Othmer, Inter-
science Encyclopedia, Inc. ll, pages 54-55, New York 11953).
Further, the resin powders of this invention can be employed
for any of the uses to which high temperature resistant
polyetherimides are used~ for example, the resin powders can
be molded in the form of bushings, electric insulators, com-
pressor veins and impellers, piston rings, gears, thread
~uides, cams, brake linings, clutch faces, abrasive articles
and the like~ The resin powders can be employed also in
the casting or spraying o~ polyetherimide/ilms on a variety
of substrates such as metal, cexamic, fabric, polymerics
., . ~
and the like.
- Other modifications and variations of the present in-
vention are possible inlight of the above teachings. It
is, therefore, to be understood that changes may be mads in
the particular embodiments of the invention described which
are within the full intended scope of the invention as de-
~ined by the appended claims
48 _
