CA1075846A - Blend of polyether amic acid-imide resin and co-resin - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

This invention is concerned with a new class of polyeth-examide-imide coresin blends wherein the coresin is selected from phanolic resins and epoxy resins. More particularly, the invention is concerned with polyetheramide-imide coresin blends which exhibit melt viscosities suitable for solvent-less-dry powder coating and curing of polyetheramide-imide coresin blends are also suitable for the manufacture of filaments, fibers, films, molding compounds, coatings, etc.

Description

~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 -.,'.'' ~ . , ~ .

~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 --. .. .
'.~'~:': ' : ' . , -,:' : ' . :

~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, : .

. ; ~ : : ~
'~ ' .

~75~ ~

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 . ~ .
'' ::, ~ - .
- , - , .. ,: . - . . . .

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~ ~

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

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 ~

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 : 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 , ;'''' ' ' ' ' : ' ' ~ ', . . ' ' ~' " . ' ,' . '. ' ~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 ' ' ' ' ": . '' .

~7~ R~-7266 O c~3 OH
CH2-CH-CH2 -O--- ~ C ~ OCH2--CH-CH2~

C~
/

, ~ OC~I2-CH-CH2 : 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 _ ;
.

~(~'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 .''. . '~, ~ ,.

-~ 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 .;
::

~.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.

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 _ :;.
` ` : ~. .

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 _ -~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 _ , 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~

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 ;: ~

- :

-~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 ~

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_ 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, ~D758'~

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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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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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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~.

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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 ~ 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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~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-~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

.

(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 :. .
, -~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_ `:

.`' :, ':'~ ' ~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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_ 39 . ` ' ~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 _ 4 3-,:, , ': - ' ' ' . ' ' ' ' : ' ~ .

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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 ?

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 _

Claims (15)

The embodiments of the invention in which an exclu-sive property or privilege is claimed are defined as follows:
1. A polyetheramide-imide resin blend of the formula:

, wherein A represents a polyamide unit and B represents a polyimide unit of a polyetheramide-imide resin, m represents a mole fraction number greater than or equal to zero, C
represents a co-resin, a represents a resin blend proportion number greater than zero and less than 1, the sum of a plus b equals 1.0, further wherein said polyamide unit is of the formula:

, and said polyimide unit is of the formula:

, wherein the O-Z-O units of said polyamide or said polyimide units are in the 3 or 3' or 4 or 4' positions and Z is a member of the class consisting of (1)
1. claim 1 (cont'd) RD-7266 , , and and (2) divalent organic radicals of the general formula where X is a member selected from the class consisting of divalent radicals of the formulas -CyH2y- , , , -0- and -S-where q is 0 or 1, y is a whole number from 1 to 5, the divalent bonds of the -0-Z-0- radical are situated on the phthalic anhydride-derived units, 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 (a) aromatic hydrocarbon radicals having from 6-20 carbon atoms and halogenated derivatives thereof, (b) alkylene radicals and cycloalkylene radicals having from 2-20 carbon atoms, C(2 8) alkylene terminated polydiorganosiloxane, and (c) divalent radicals included by the formula where Q is a member selected from the class consisting of - 0 - , -C- , -S- , -S-, and -CxH2x- , and x is a whole number from 1 to 5 inclusive and further where said co-resin is selected from phenolic resins having an average molecular weight in excess of 125, and epoxy resins possessing at least two 1,2 epoxide groups having an epoxide equivalent weight in excess of 70.
   2. A solventless-dry powder comprising an homogeneous poly-etheramide-imide resin blend of the formula:
   
   wherein A represents a polyamide unit and B represents a polyimide unit of a polyetheramide-imide resin, m represents a mole fraction number greater than or equal to zero, C
   represents a co-resin, a represents a resin blend proportion num-ber greater than zero and less than 1, the sum of a plus b equals l.0, further wherein said polyamide unit is of the formula Claim 2 (cont'd) RD-7266 and said polyimide unit is of the formula:
   
   wherein the 0-Z-0 units of said polyamide or said polyimide units are in the 3 or 3' or 4 or 4' positions and Z is a member of the class consisting of (1) and and (2) divalent organic radicals of the general formula
2. Claim 2 continued:
   
   where X is a member selected from the class consisting of divalellt radicals of the formulas -CyH2y- , -C- , -0- and -S- , where q is 0 or 1, y is a whole number from 1 to 5, the divalent bonds of the -0-Z-0- radical are situated on the phthalic anhydride-derived units 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 (a) aromatic hydrocarbon radicals having from 6-20 carbon atoms and halogenated derivatives thereof, (b) alkylene radicals and cycloalkylene radicals having from 2-20 carbon atoms, C(2-8) alkylene terminated polydiorganosiloxane, and (c) divalent radicals included by the formula where Q is a member selected from the class consisting of -0- , -C- -S- , -S- , and -CxH2x-' and x is a who].e number from 1 to 5 inclusive and further wherein said co-resin is selected from phenolic resins having an average molecular weight in excess of 125, and epoxy resins possessing at least two 1,2 epoxide groups having an epoxide equivalent weight in excess of 70.
3. 3. A solventless-dry powder of the composition of claim 2, wherein the powder particles have a diameter within the range of from about 5 to about 200 microns, a sintering tem-perature range (STR) of from about 75 to about 200° C., a viscous flow temperature range (VFTR) of from about 75° to about 240°C., and a leveling temperature range (LTR) of from about 160 to 280°C.
4. 4. A solventless-dry powder of the composition of claim 3, wherein said coresin is a phenolic resin having an average molecular weight within the range of from about 350 to 1,000.
5. 5. A solventless-dry powder of the composition of Claim 3 wherein said coresin is an epoxy resin having an equiva-lent weight in the range of from about 70-5,000.
6. 6. A solventless dry powder of the composition of Claim 5 wherein said equivalent weight is in the range of from about 450 to 1,000.
7. 7. A solventless-dry powder coating of the composition of claim 4, 5 or 6 wherein the powder particles have a diameter of from about 5 to about 60 microns, a "STR" of 140 to 190°C.
   a "VFTR" of 155 to 220 C,, and a "LTR" of from 200 to 250°C.
8. 8, A solventless-dry powder of the composition of claim 4, wherein the phenolic resin has a melting point range of from about 40 to about 180°C.
9. 9. A solventless-dry powder of the composition of claim 4, 5 or 6 wherein a is at least equal to the number 0.5.
10. 10. An electrically conductive metal substrate coated with a polyetheramide-imide co-resin blend of the composition of claim 4, 5 or 6.
11. 11. The resin blend of claim 1, 2 or 3 wherein a has a value of at least 0.5.
12. 12. The resin blend of claim 1, 2 or 3 wherein a has a value of at least 0.75.
13. 13. The resin blend of claim 1, 2 or 3 wherein z is
14. 14. The resin blend of claim 8 wherein said phenolic resin comprises phenolic residues of phenols having tertiary acyclic or cyclic hydrocarbyl substituents in the para position.
15. 15. The resin blend of claim 8 wherein said phenols are para tertiary butyl phenols.