Self-bondable polyamides are prepared by reacting an aromatic diisocyanate or diamine with a mixture of terephthalic acid and an aliphatic dibasic acid having at least 6 carbon atoms. These self-bondable amides can also be used as topcoats for wires having basecoats of another polymer, e.g. a polyester, polyester-imide, or polyamideimide.

BACKGROUND OF THE INVENTION 
The present invention relates to a novel self bondable aromatic aliphatic 
polyamide. 
An all-aromatic polyamide as made in accordance with Allard U.S. Pat. No. 
3,642,715 does not exhibit self-bonding characteristics even when tested 
via the NEMA Bonding Test No. 57.1.1.2. at temperatures up to 260.degree. 
C. The all-aliphatic polyamides as described by the work of Otis U.S. Pat. 
No. 4,216,263 and Kawaguchi U.S. Pat. No. 4,163,826 are thermoplastic in 
nature and exhibit good bonding characteristics but do not offer the 
excellent humidity resistance and resistance to attack by refrigerants as 
do the aromatic-aliphatic polyamides of the present invention. 
Gilman U.S. Pat. No. 2,268,586 has a broad teaching of making polyamides by 
reacting a dibasic acid with a diisocyanate but does not show 
self-bondable polyamides. 
Onder U.S. Pat. No. 4,072,665 discloses a novel copolymer of the formula 
##STR1## 
where R is 60 to 85 percent of an aliphatic dibasic carboxylic acid with 
(CH.sub.2).sub.x recurring units and x being an integer of 7 to 12 
inclusive, the remaining 15 to 40 percent of R being m-phenylene. The 
proportions are indicated to be critical in Onder. Onder also indicates on 
column 6, lines 43-52 that a portion of the recurring units up to 10% can 
have R from a different dicarboxylic acid, e.g. terephthalic acid. Onder 
uses his products for many things including wire coatings, column 6, lines 
11-22. However, Onder makes no mention of a solution cast film which is 
baked and yet retains self-sealing or adhesive properties. 
SUMMARY OF THE INVENTION 
There have now been prepared random aromatic-aliphatic copolyamides having 
the recurring unit 
##STR2## 
where AL is the divalent hydrocarbon residue of an unsubstituted aliphatic 
dicarboxylic acid having 6 to 36 carbon atoms or more, usually AL is 
(CH.sub.2).sub.x where x is 4 to 34, preferably 6 to 12, most preferably 
10. However, AL can be the residue of an unsaturated dicarboxylic acid, 
e.g. dimerized linoleic acid or dimerized oleic acid or dimerized tall 
oil. R is tolylene, phenyl, 
##STR3## 
where F is O, CH.sub.2 or SO.sub.2. Less preferably all or a part of R can 
be cycloaliphatic, e.g. cyclohexylene or methylenedicyclohexyl, Ar is 
p-phenylene, y is 35 to 80% of the recurring units and z is 65 to 20% of 
the recurring units. Usually y is 40 to 70% of the recurring units and 
preferably y is about 60 to 70%, most preferably 65% of the recurring 
units. If y is above 70% there is a tendency to gel on standing. 
The copolyamides can be prepared in conventional manner by reacting a 
mixture of the dicarboxylic acids, e.g. dodecanedioic acid and 
terephthalic acid with a diisocyanate, e.g. toluene diisocyanate or 
methylene diphenyldiisocyanate, or with the corresponding diamine, e.g. 
toluene diamine, 4,4'-methylene diphenyl diamine (methylene dianiline), 
oxydianiline, phenylene diamine, diaminodiphenyl sulfone, or a mixture of 
such diisocyanates or of such diamines. As indicated there can also be 
employed a minor amount of 4,4'-methylene diphenyl diamine or cyclohexyl 
diamine. In reacting with the diamine rather than the diisocyanate it is 
of course possible to employ other acylating agents than the acid, e.g. 
there can be used the acyl halides, e.g. the dichloride or dibromide of 
dodecandioic acid or the lower alkyl esters, e.g. dimethyl dodecandioate, 
diethyl dodecandioate, and dibutyl dodecanedioate. 
Preferably in the formula R has the mole percent ratio of 
4-methyl-m-phenylene/2-methyl-m-phenylene/4,4'-methylene diphenylene in 
the range of 40/10/50 to 80/20/0. The reaction is carried out in an amide 
solvent such as N-methyl-2-pyrrolidone (NMP). 
The copolyamides of the invention are useful as a self-bonding coating for 
magnet wire. This coating is usually applied in an amide based solvent 
system, e.g., N-methyl pyrrolidone or a mixture of N-methyl pyrrolidone 
and an aromatic hydrocarbon. The major advantages offered by this novel 
enamel are: 
(1) High temperature retention of bond strength. 
(2) The quality of the base coat is not lessened, and in some cases, the 
quality of the base coat is improved by the bonding overcoat. 
(3) The coating is resistant to attack by refrigerants. 
(4) The coating has improved humidity resistance. 
(5) The coating has improved chemical resistance. 
(6) The coating is less costly than commercially available alternatives. 
(7) The end user's cost is reduced by elimination of a costly secondary 
insulation. 
(8) By eliminating the solvent-borne secondary insulation requirement, the 
bond coat offers obvious ecological advantages. 
(9) Good adhesion to self-supporting high-temperature films. 
Thus, the novel, self-bonding wire coating provides the magnet wire user an 
economical and ecological alternative with significant improvements in 
bond strengths, hermetic resistance, and chemical resistance when compared 
to other self-bond wire coatings. This novel coating also offers the motor 
manufacturer an option to eliminate secondary insulations as the 
self-bonding wire coating will produce results equivalent to or better 
than those achieved with the secondary insulations currently used. 
It was previously pointed out that the copolyamides of the present 
invention are superior, in humidity resistance and resistance to attack by 
refrigerants, to the products of Otis U.S. Pat. No. 4,216,263. Thus when a 
sample of a polyamide as described in Otis is subjected to a 100 percent 
humidity at 70.degree. C., it exhibits an initial resistance of about 
370,000 megohms. After aging one week, the megohm resistance was about 
280,000 megohms; after two weeks, the resistance had dropped to about 
160,000 megohms. The aromatic-aliphatic polyamide of the present invention 
(based on Mondur TD-80, 4,4-methylene diphenylenediisocyanate, 
terephthalic acid and dodecanedioic acid), when submitted to this test, 
gave the following results: 
______________________________________ 
After After 
Initial One Week Two Weeks 
______________________________________ 
422,000 megohms 
900,000 megohms 
820,000 megohms 
______________________________________ 
The dielectrics of the all-aliphatic polyamides of Otis were reduced by 50 
percent after two weeks at 100 percent relative humidity and 70.degree. C. 
The aromatic-aliphatic polyamides of this invention, however, did not 
significantly change after the two-week aging. The all-aliphatic nylons 
are true thermoplastics, unlike the aromatic-aliphatic polyamides of the 
invention which, when initially bonded at 200.degree. C., retain good bond 
strength at 200.degree. C. The aromatic-aliphatic polyamides of the 
invention, when coated over a polyester of the type described by Meyer in 
U.S. Pat. Nos. 3,201,276 and 3,211,585, will upgrade the base polyester to 
a NEMA Class 155.degree. C. or greater magnet wire coating system. The 
entire disclosure of the Meyer patents are hereby incorporated by 
reference and relied upon. When coated over other wire enamels or wire 
enamel systems, the inherent properties of the coated wire are not 
adversely effected. The aliphatic-aromatic polyamides of this invention 
will self-bond at temperatures of 170.degree. C. or greater when tested in 
accordance with NEMA Test Specification 57.1.1.2 with resulting bond 
strengths of greater than seven pounds when broken at 180.degree. C. 
When this novel enamel is coated over a self-supporting, high-temperature 
film, such as a polyimide, polyparabanic acid, polyamide, or 
polyamide-imide film, then baked to dry, the film may then be self-bonded 
and will exhibit outstanding inner laminar adhesion. 
If a polyamide, in 70/30 nmp/xylene, is made from 100% of an alkanedioic 
acid such as dodecanedioic acid and a mixture of toluene diisocyanate and 
methylene diphenyl diisocyanate, then the enamel product gels on standing. 
In fact there is a tendency for gelation to occur if the amount of 
dodecanedioic acid goes above 70 mole percent and especially above 78 mole 
percent based on the total of dodecanedioic acid and terephthalic acid. 
Among the advantages of the copolyamides of the invention, in addition to 
or in amplification of those set forth above are: 
(1) The wire coating is bondable at 200.degree. C. and yet retains good 
bond strength at 180.degree. C. However, once the polymer is "Heat Set" 
above the apparent glass transition temperature of the aromatic-aliphatic 
polyamide, the apparent glass transition temperature increases, thus 
giving some thermoset properties to the coating. 
(2) The aromatic-aliphatic polyamide system of the invention is the only 
amide bonding system offered which is not in part a physical blend of an 
all aliphatic amide such as Nylon 6;6,6; 11 or 12. The aromatic-aliphatic 
polyamide is, however, an in situ reaction product of an aromatic diacid 
and an aliphatic diacid, preferably with a blend of aromatic diisocyanates 
to yield a random aromatic-aliphatic polymer. The preferred reactants are 
terephthalic acid and dodecanedioic acid with toluene diisocyanate and 
methylenediphenyl diisocyanate in a 70:30 mole ratio. The reaction is 
carried out in an amide-type solvent such as N-methyl-2-pyrrolidone. 
(3) The aromatic-aliphatic polyamide, when coated over ISONEL 200, yields a 
Class 155.degree. C. magnet wire; and, with the exception of the heat 
shock, displays Class 180.degree. C. properties. 
When coated over ISOMID, excellent properties as a Class 180.degree. C. 
magnet wire are observed. 
(4) The aromatic-aliphatic polyamide coated over ISONEL 200 pases the A. O. 
Smith Freon Blister Test; conventional Nylon 6,6 coated over ISONEL 200 
fails this test. 
(5) The moisture resistance of the aromatic-aliphatic polyamide is also 
superior to the Nylon 11 types. 
(6) The aromatic-aliphatic polyamides offer a significant cost advantage 
over the systems based upon Nylon 11 or 12. 
As indicated above the enamels of the invention exhibit good bond strengths 
when coated over ISONEL 200 and ISOMID wire enamel. Thus when bonded at 
200.degree. C. for 20 minutes they have shown bond strengths of 1 to 6.2 
lbs. and even up to 7.4 pounds at 180.degree. C. without degrading other 
wire properties by application of the bond coat. 
The heat-bondable copolyamide film of the invention can be applied by 
conventional wire coating techniques to give a wire that may be wound into 
coils, armatures, stators, etc., and heat bonded, thereby eliminating the 
need for an impregnating varnish, to give a wire-insulation system of 
unusual thermal resistance. In the process of eliminating the need for a 
varnish dip, the need for expensive dipping apparatus ovens, lengthy cure 
cycles, and high energy costs are eliminated. 
The bondable copolyamide of the invention can be employed, for example, as 
a top coat over a wire having a base coat or coats of, for example: 
1. a glycerine or other aliphatic polyhydric alcohol polyester, e.g. 
glycerineethylene glycol terephthalate polymer as in Precopio U.S. Pat. 
No. 2,936,296, 
2. tris(2-hydroxyethyl)isocyanurate polyester, e.g. tris(2-hydroxyethyl) 
isocyanurate(THEIC)ethylene glycol-terephthalate polymer as in Meyer U.S. 
Pat. No. 3,342,780, 
3. a polyester coated with an amide-imide polymer, e.g. the polyester of 
Precopio or Meyer 3,342,780 coated with an amide-imide polymer as shown in 
Koerner U.S. Pat. No. 3,022,200 and Standard Oil British Pat. No. 
1,056,564. 
4. a polyester-imide which is the reaction product of THEIC, ethylene 
glycol, terephthalic acid (or isophthalic acid), methylene dianiline (or 
oxydianiline) and trimellitic anhydride, e.g. as in Meyer U.S. Pat. No. 
3,426,098. In place of THEIC, there can be used glycerine, e.g. as in the 
polyester-imides of Schmidt U.S. Pat. No. 3,697,471. Likewise, there can 
be used as the base coat the diethylene glycol or triethylene glycol 
monoether modified polyester-imide resins of Keating U.S. Pat. No. 
4,119,608, 
5. amide-imide coated polyester-imide as in the Koerner and Standard Oil 
patents, 
6. monolithic amide-imide as in the Standard Oil patent, 
7. polyimide such as Pyre ML as in Edwards U.S. Pat. Nos. 3,179,634; 
3,179,630; 3,179,631; 3,179,632, and 3,179,633, 
8. as a coating over an acrylic (acrylic-methacrylic acid ester) top coated 
polyimide of the type of Lecton (DuPont), 
9. conventional Formvar (polyvinyl formal), epoxy (e.g. bisphenol 
A-epichlorohydrin), urethane, and nylon top coated urethane. The entire 
disclosures of the Meyer Pat. No. 3,342,780, Precopio, Koerner, Standard 
Oil, Keating, Meyer U.S. Pat. No. 3,426,098, and the Edwards patents are 
hereby incorporated by reference and relied upon. 
The wire enamels can be applied to either bare or base coated copper, 
aluminum, silver, or other wires using conventional coating procedures and 
wire speeds, e.g., 30-150 ft/min. and curing the wire is carried out at 
conventional temperatures. The speed is adjusted according to wire size 
and enamel to obtain optimum cure as is known in the art. 
The copolyamides of the invention are also useful as bondable coatings over 
film wrapped wire, e.g. 
1. Kapton--a polyimide film of DuPont as in the Edwards patents 
2. Nomex--a DuPont aromatic polyamide (isophthalic acid with an aromatic 
diamine). 
The copolyamides of the invention can be used as adhesives to apply over 
self-supporting films, e.g. used in printed circuit boards and capacitors. 
Typical self-supported films include Kapton polyimide, Mylar (polyethylene 
terephthalate) polyester, Nomex, polytetrafluoroethylene and 
perfluoroethylene-perfluoropropylene copolymer. 
The copolyamides of the invention can be employed as cast films for 
adhesive use. The film is cast from solution and can then be used as an 
adhesive. 
In film, strand or filament form the copolyamide can be used as a 
substitute for Dacron in wrapped glass cloth. Dacron is not high 
temperature resistant. Hence replacing the Dacron filaments by filaments 
of the copolyamide of the invention gives higher temperature resistant 
products. 
Nomex is available as cast or sheet insulation. The heat bondable 
copolyamide of the invention can be used as a wrapping therefore to hold 
the Nomex together.

The composition can comprise, consist essentially of, or consist of the 
materials set forth. 
EXAMPLE 1 
This example is a working example of the present invention. 
______________________________________ 
Load 
Raw Materials in Grams 
______________________________________ 
(1) N--methyl-2-pyrrolidone 4168 
(2) Toluene diisocyanate (Mondur TD-80)* 
1033 
(3) 4,4' Methylene diphenyldiisocyanate 
637 
(4) Terephthalic Acid 494 
(5) Dodecanedioic Acid 1267 
(6) Xylene 2243 
(7) N--methyl-2-pyrrolidone 1050 
______________________________________ 
*Mondur TD80 is a 80/20 blend of 4methyl-m-phenylene diisocyanate and 
2methyl-m-phenylene diisocyanate and is commercially available from Mobay 
Chemical Company, Pittsburgh, Pennsylvania. 
Parts one through three charged at room temperature into a 12-liter, 
round-bottom reaction flask, equipped with an agitator, a thermometer, an 
inert gas purge, and a water-cooled condenser fitted with a flexible tube 
which was immersed in a flask containing a mixture of water and denatured 
ethyl alcohol. (The reaction by-products carried through the condenser by 
the carbon dioxide and nitrogen are trapped in the water-alcohol 
solution). Parts four and five were added at room temperature with 
agitation and a blanket of nitrogen was applied over the reaction. The 
temperature was raised slowly by use of an electric heating mantel to 
approximately 75.degree. C. when carbon dioxide evolution began. The 
external heat was then reduced and the temperature of the batch was 
allowed to rise over a four-hour time period to approximately 170.degree. 
C. At about 80.degree. C., the batch became clear. After an approximate 
four-hour hold at 170.degree. to 175.degree. C., the reaction was allowed 
to cool slowly to room temperature over night. The next morning the 
reaction mixture was sampled and a 60 percent solution in 
N-methyl-2-pyrrolidone was determined to have a viscosity at 25.degree. C. 
on the Gardner-Holdt scale of W 1/2. Parts six and seven were then added. 
The final viscosity of the solution at 25.degree. C. was Z on the 
Gardner-Holdt scale, or 2,500 centipoises as measured by a Brookfield RVT 
Viscometer. 
The percent non-volatiles of the solution were determined to be 27 percent 
by baking a two-gram sample for two hours at 200.degree. C. The specific 
gravity of the solution was determined to be 1.025 at 25.degree. C. This 
solution was then used to overcoat a commercially available polyester 
(ISONEL 200)**. The test properties were as shown in Table One. It was 
also coated over a commercially available polyester-imide (ISOMID)*** and 
tested as shown in Table One. 
FNT **ISONEL 200 is a commercially-available polyester wire coating from 
Schenectady Chemicals, Inc., Schenectady, N.Y. and is 
tris(2-hydroxyethyl)isocyanurate-ethylene glycol-terephthalic acid 
polymer. 
FNT ***ISOMID is a commercially-available polyesterimide wire enamel also from 
Schenectady Chemicals, Inc., Schenectady, N.Y. and is a 
tris(2-hydroxyethyl)isocyanurate-ethylene glycol terephthalic 
acid-methylene dianiline-trimellitic anhydride polymer. 
The temperature of coating the wires in all of the examples was 
370.degree.-480.degree. C. 
EXAMPLE 2 
______________________________________ 
Load 
Raw Materials in Grams 
______________________________________ 
(1) N--methyl-2-pyrrolidone 4168 
(2) Toluene diisocyanate (Mondur TD-80) 
1033 
(3) 4,4-Methylene diphenyldiisocyanate 
637 
(4) Terephthalic Acid 494 
(5) Dodecanedioic Acid 1267 
(6) Xylene 1982 
(7) N--methyl-2-pyrrolidone 910 
______________________________________ 
The reaction was carried out much in the same fashion as described in 
example one, with the exception of the over night cooling step. The 
reaction medium was sampled after a three-hour hold at 165.degree. to 
180.degree. C. at 60 percent in N-methyl-2-pyrrolidone and found to have a 
viscosity of V 1/2 at 25.degree. C. on the Gardner-Holdt Scale. The batch 
was then reduced with six and seven to a final viscosity of Y 1/4 at 
25.degree. C. on the Gardner-Holdt Scale at 28.45 percent non-volatiles 
determined as described in Example One. 
The material was then coated over a polyester (ISONEL 200), a polyester 
imide (ISOMID), a polyester overcoated with a polyamide-imide, (ISONEL 200 
overcoated with trimellitic anhydride-methylene dianiline polymer), a 
polyamide-imide (trimellitic anhydride-methylene dianiline polymer) wire 
coating and as a monolithic enamel. The results of the testing on the 
coated conductors are as shown in Table one. 
EXAMPLES 3 THROUGH 8 
Examples Three through Eight describe the effects of the mole percent ratio 
of aliphatic diacid to aromatic diacid. The effects on bond strength are 
shown on Graph Number One. (Bond strength versus percent aliphatic 
diacid). Also shown on Graph Number One is the relationship of bond 
strength to breaking temperature. The other properties of the coated 
conductors are as displayed in Table One. 
The general procedure for making these enamels is as described in Example 
One. 
______________________________________ 
Example 3 4 5 6 7 8 
______________________________________ 
Reactants Batch weight 
______________________________________ 
(1) N--methyl-2- 
644 611 623 633 655 664 
pyrrolidone 
(2) Toluene 159 159 159 159 159 159 
diisocyanate 
(3) 4,4'-methylene 
98 98 98 98 98 98 
diphenyl 
diisocyanate 
(4) Terephthalic 
76 141 118 97 54 32 
Acid 
(5) Dodecanedioic 
194 104 135 164 224 254 
Acid 
(6) Xylene 327 382 346 331 335 366 
(7) N--methyl-2- 
119 140 241 140 126 210 
pyrrolidone 
Gardner-Holdt 
Y3/4 X1/2 Y+ Z+ Y1/4 Y 
Viscosity @ 25.degree. C. 
Percent Non- 
27.8 24.9 25.2 26.8 23.8 25.7 
Volatiles 
Determined 
2 gm., 2 hr., 
200.degree. C. 
______________________________________ 
EXAMPLE 9 
This example describes the use of an aliphatic acid as described in the 
disclosure where X equals four. 
______________________________________ 
Reactants Batch Weight 
______________________________________ 
(1) N--methyl-2-pyrrolidone 
600 
(2) Toluene diisocyanate 171 
(3) 4,4' Methylene diphenyldiisocyanate 
105 
(4) Terephthalic Acid 81 
(5) Adipic Acid 133 
(6) Xylene 257 
Gardner-Holdt Viscosity (25.degree. C.) 
W1/2 
Determined Percent Non-Volatiles 
32.4 
(2 grams, 2 hours, 200.degree. C.) 
______________________________________ 
This example was prepared as described in Example One. 
The properties of this enamel when used to overcoat ISOMID are as described 
in Table One. 
EXAMPLE 10 
This example describes the use of an aliphatic diacid as described in the 
disclosure where X equals seven. 
______________________________________ 
Reactants Batch Weight 
______________________________________ 
(1) N--methyl-2-pyrrolidone 
622 
(2) Toluene diisocyanate 165 
(3) 4,4' Methylene diphenyl diisocyanate 
161 
(4) Terephthalic Acid 78 
(5) Azelaic Acid 165 
(6) N--methyl-2-pyrrolidone 
198 
(7) Xylene 412 
Gardner-Holdt Viscosity (@ 25.degree. C.) 
X3/4 
Determined percent Non-Volatiles 
22.9 
(2 grams, 2 hours, 200.degree. C.) 
______________________________________ 
This example was prepared in the same fashion as Example One. This enamel 
was applied on 18-AWG copper wire over ISOMID. The electrical test 
properties are as shown in Table one. 
EXAMPLE 11 
This example demonstrates the use of a diabasic acid where X equals eight. 
______________________________________ 
Reactants Batch Weight 
______________________________________ 
(1) N--methyl-2-pyrrolidone 
560 
(2) Toluene diisocyanate 145 
(3) 4,4' Methylene diphenyl diisocyanate 
89 
(4) Terephthalic Acid 69 
(5) Sebacic Acid 156 
(6) N--methyl-2-pyrrolidone 
207 
(7) Xylene 411 
Gardner-Holdt Viscosity (@ 25.degree. C.) 
X1/2 
Determined percent Non-Volatiles 
24.2 
(2 grams, 2 hours, 200.degree. C.) 
______________________________________ 
This example was prepared in accordance with the procedure described in 
Example One. The test results obtained when this enamel was applied over 
18-AWG copper wire coated with ISOMID are shown in Table One. 
EXAMPLE 12 
This example indicates that the allowable number of methylene groups 
between the two carboxyl groups of the aliphatic diacid may not have an 
upper limit. 
______________________________________ 
Reactants Batch Weight 
______________________________________ 
(1) N--methyl-2-pyrrolidone 
585 
(2) Toluene diisocyanate 94 
(3) 4,4' methylene diphenyl diisocyanate 
68 
(4) Terephthalic Acid 45 
(5) Empol 1010* 283 
(6) N--methyl-2-pyrrolidone 
140 
(7) Xylene 310 
Gardner-Holdt Viscosity (@ 25.degree. C.) 
Y1/4 
Determined percent Non-Volatiles 
29.4 
(2 grams, 2 hours, 200.degree. C.) 
______________________________________ 
*Empol 1010 is a C.sub.36 dimerized fatty acid available from Emery 
Industries, Inc., Cincinnati, Ohio. 
This reaction was cooked in accordance with the procedure outlined in 
Example One. The test results obtained when this enamel was applied over 
18-AWG copper wire coated with ISOMID are shown in Table One. 
EXAMPLE 13 
This working example demonstrates the use of a cyclic aliphatic 
diisocyanate to replace a portion of the aromatic diisocyanate. 
______________________________________ 
Reactants Batch Weight 
______________________________________ 
(1) N--methyl-2-pyrrolidone 
600 
(2) Toluene diisocyanate 146 
(3) Desmondur W* 97 
(4) Dodecanedioic Acid 179 
(5) Terephthalic Acid 76 
(6) N--methyl-2-pyrrolidone 
155 
(7) Xylene 323 
Gardner-Holdt Viscosity (@ 25.degree. C.) 
Z1/4 
Determined Percent Non-Volatiles 
27.5 
(2 grams, 2 hours, 200.degree. C.) 
______________________________________ 
*Desmondur W is a cycloaliphatic diisocyanate available from Mobay 
Chemical Company, Pittsburgh, Pennsylvania. 
This enamel was prepared as described in Example One. It was then applied 
as an overcoat to ISOMID-coated copper wire. The test results obtained 
from this construction are as shown in Table One. 
EXAMPLE 14 
This example shows the use of all toluene diisocyanate to make an 
acceptable bond coat. 
______________________________________ 
Reactants Batch Weight 
______________________________________ 
(1) N--methyl-2-pyrrolidone 
606 
(2) Toluene diisocyanate 226 
(3) Dodecanedioic Acid 194 
(4) Terephthalic Acid 76 
(5) N--methyl-2-pyrrolidone 
210 
(6) Xylene 350 
Gardner-Holdt Viscosity (@ 25.degree. C.) 
X1/4 
Determined percent Non-Volatiles 
27.2 
(2 grams, 2 hours, 200.degree. C.) 
______________________________________ 
This example was prepared using the procedure described in Example One. 
However, as indicated no 4,4'-methylene diphenyl diisocyanate was 
employed. When coated over 18-AWG ISOMID coated wire, the bond coat gave 
the properties as shown in Table One. 
EXAMPLE 15 
This example defines the lower preferred limit of toluene diisocyanate in 
the bond coat. 
______________________________________ 
Reactants Batch Weight 
______________________________________ 
(1) N--methyl-2-pyrrolidone 
615 
(2) Toluene diisocyanate 150 
(3) 4,4' Methylene diphenyl diisocyanate 
179 
(4) Dodecanedioic Acid 70 
(5) Terephthalic Acid 140 
(6) N--methyl-2-pyrrolidone 
35 
(7) Xylene 280 
Gardner-Holdt Viscosity (@ 25.degree. C.) 
Y 
Determined Percent Non-Volatiles 
31.4 
(2 grams, 2 hours, 220.degree. C.) 
______________________________________ 
This enamel was also cooked as described in Example One. It was then 
applied to ISOMID coated 18-AWG copper wire giving the test results as 
reported in Table One. 
COMATIVE EXAMPLE 1 
A commercial solution of Nylon 66 was coated over a polyester wire enamel, 
namely, ISONEL 200. The resulting magnet wire exhibited the properties 
shown in Table One. 
COMATIVE EXAMPLE 2 
A solution of Nylon 11 was prepared in accordance with U.S. Pat. No. 
4,216,263 by Otis. The viscosity of this solution was approximately Z5 1/2 
on the Gardner-Holdt Scale at 25.degree. C. The percent non-volatiles of 
the solution was determined to be 16.1 percent by baking a two-gram sample 
for two hours at 200.degree. C. This enamel solution was coated over a 
polyester-imide of the ISOMID type on AWG-24 copper wire. The electrical 
and bonding test results are shown in Table One. 
COMATIVE EXAMPLE 3 
A solution of Nylon 11 was prepared in accordance with U.S. Pat. No. 
4,216,263 by Otis. The viscosity of the solution was approximately Z2 3/4 
on the Gardner-Holdt Scale at 25.degree. C. at approximately 16.1 percent 
non-volatiles determined as in Example One. This enamel was coated over a 
polyesterimide wire coating, namely ISOMID on 18-AWG copper wire. The test 
results are shown on Table One. A comparison of the bond strength of this 
example to the preferred composition of this disclosure as described by 
Example One is shown on Graph Number Two. 
COMATIVE EXAMPLE 4 
A solution of Nylon 11 was prepared in accordance with U.S. Pat. No. 
4,216,263 Otis. The viscosity of this solution was approximately Z3 1/2 on 
the Gardner-Holdt Scale at 25.degree. C. The percent non-volatiles 
determined as in Example One were 16.8 percent. This enamel was coated 
over a polyester wire coating, namely ISONEL 200 on 18-AWG copper wire. 
The electrical and bonding test results are as shown in Table One. 
______________________________________ 
Abbreviation Key for Table 1 
______________________________________ 
F.O.M. Figure of Merit 
Hrs. Hours 
FPM Feet per Minute 
VPM Volts per Mil 
Base Coat: 
PE Polyester of the ISONEL .RTM. 200 type 
PEI Polyester-imide of the ISOMID .RTM. type 
PAI Aromatic polyamide-imide 
PAI/PE Polyamide imide based upon 
4,4' methylene diphenyl diisocyanate 
and trimellitic anhydride over- 
coated over a polyester of the 
ISONEL .RTM. 200 type 
None Indicates the bond coat was applied 
in eight passes to obtain a three- 
mil build 
Build total increase in the wire diameter 
as a result of the coating. 
Wire Size All AWG sizes 
Speed The rate the wire traveled as it 
was coated in multiple passes and baked 
in a 15-foot, gas-fired oven. -Appearance: 
G Indicates good or smooth surface. 
VSW Indicates smooth surface with a 
very slight wave. 
SW Indicates minor flaws in the coating 
surface 
Heavy Grain Indicates a rough surface without 
blisters 
Rough Is an indication the coating is 
unacceptable as it may contain 
blisters, or a very heavy grain, 
or an extreme wave. 
(+) Indicates slightly better than given 
rating 
(-) Indicates slightly worse than given 
rating 
Snap Measured in accordance with NEMA 
Standards Publication Part 3, 
paragraph 3.1.1. 
Mandrel After Snap 
Smallest mandrel around which wire 
which has been "snapped" as above can 
be wound without exhibiting surface 
cracks. 
Abrasion Measured in accordance with NEMA 
Unilateral Standard Publication Part 3, 
Scrape paragraph 59.1.1. 
Windability 1500 volts are passed through a 
six foot long wire sample which is 
wrapped around a specified mandrel. 
The mandrel moves along the wire 
at fixed rate elongating and 
abrading the wire. Failure is 
described when three shorts occur 
along the surface of the sample. 
Cut Through Measured in accordance with NEMA 
Standards Publication Part 3, 
paragraph 50.1.1.2. 
Heat Shock Tested in accordance with NEMA 
Standards Publication, Part 3, 
paragraph 4.1.1. 
Burn Out Tested in accordance with NEMA 
Standards Publication, Part 3, 
paragraph 53.1.1.4. F.O.M. is 
Figure of Merit calculated as 
described in NEMA Standards 
Publication, Part 3, paragraph 
53.1.1.3. 
A. O. Smith A five-foot sample of wire is 
Freon Blister 
wound into a coil which produces 
Test four to six percent stretch, baked for 
two hours at 150.degree. C., then cooled 
to room temperature. The samples 
are then placed in a freon bomb 
charged with Freon 22 .RTM. and the 
pressure in the bomb is brought up 
to 600 pounds per square inch by 
heating and held six hours. After 
the six-hour hold, the pressure is 
immediately released and coils are 
placed in an oven at 150.degree. C. for 
four hours. The coils are then 
removed from the oven and checked 
for blistering. One large blister, 
or two medium, or five small blister 
constitutes a failure. The wire is 
then wrapped around a five times 
mandrel for ten turns and checked 
for cracks or peeling. If the 
coating cracks or peels, it is 
a failure. Finally, the wire is 
made into a twisted pair and 
dielectrics are determined in 
accordance with NEMA Standards 
Publication, Part 3, paragraph 
7.1.1.3. 
Dielectrics: 
Dry Determined in accordance with NEMA 
Standards Publication, Part 3, 
paragraph 7.1.1.3. 
Wet After soaking in water for 24 hours, 
the samples are tested as described 
above. 
Bonding Determined following the procedure 
described in NEMA Standards Publication 
Part 3, paragraph 57.1.1.2. at the 
temperature stated under Bonding 
Temperature. 
Dissipation Factor 
Tested in accordance with NEMA 
Standards Publication, Part 3, 
Paragraph 9.1.1.2. 
Heat Aging Number of hours up to 168 (at 180.degree. C.) 
at 180.degree. C. 
required for a sample to be baked 
to fail a post winding of around a 
one times mandrel. 
______________________________________ 
3 TABLE 1 
Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- ple ple ple ple ple ple 
ple ple 1 2 3 4 5 6 7 8 
PAI/ Basecoat PE PEI PE PEI PEI PEI PE PAI None None PEI PEI PEI P 
EI PEI PEI Build (mils) bondcoat/basecoat 1.0/2.0 1.0/2.0 1.0/2.1 
0.9/1.9 1.0/2.0 1.0/2.0 1.1/ 1.0/2.0 1.0/2.0 1.0/2.0 1.0/2.0 1.0/2.0 
1.0/2.0 1.0/2.1 0.7/2.3 Wire Size (AWG) 18 18 18 24 24 24 18 18 
18 18 18 18 18 18 18 18 Wire Speed (fpm) 50 50 50 100 120 130 50 50 40 
50 50 50 50 50 50 50 Appearance, bondcoat/basecoat VSW/ VSW/ VSW/ VSW/ 
VSW/ VSW-/ VSW/ VSW/ VSW/ VSW/ VSW/ VSW/ VSW/ VSW-/ VSW VSW VSW+ VSW 
VSW VSW VSW/ VSW VSW VSW VSW VSW VSW VSW VSW MECHANICAL 
PROPERTIES Mandrel, before snap 1X 1X 1X 1X 1X 1X 1X 1X 1X 1X 1X 1X 1X 
1X 1X 1X Snap (OK or Fail) OK OK OK OK OK OK OK OK OK OK OK OK OK OK OK 
OK Mandrel, after snap 1X 1X 1X 1X 1X 1X 1X 1X 1X 1X 1X 1X 1X 1X 1X 1X 
Abrasion (gms.) 2000+ 2000+ 1933 1000+ 1000+ 1000+ 2000+ 1816 2000+ 
2000+ 1883 1866 1800 1950 2000+ 1933 Windability 25 20 17 14 Helical 
Coil Bonding; Bond Temp., .degree.C. 200 200 200 200 200 200 200 200 
200 200 200 200 200 200 200 Bond Str., lbs. @ 25.degree. C. 10.63 16.09 
6.6 9.7 9.2 19.80 18.65 -- -- 21.7 0.4 1.0 2.9 16.2 12.5 150.degree. 
C. 6.40 10.88 4.9 5.2 5.6 -- -- -- -- 10.9 0.0 1.0 2.0 8.0 5.2 
180.degree. C. 3.52 5.87 1.7 0.9 0.8 4.3 3.43 7.4 3.68 6.2 0.0 0.0 1.4 
4.7 1.5 200.degree. C. 2.09 2.64 0.4 0.4 0.2 -- -- -- -- 3.2 0.0 
0.0 1.4 2.2 1.1 THERMAL PROPERTIES Cut Through Temp., .degree.C. 365 340 
355 342 318 316 385 325 280 260 Heat Shock, 1X 50 80 70 80 60 70 80 70 
80 80 (1/2 Hr. at test, 2X 80 90 80 90 80 80 90 90 90 90 temp., 20%, 3X 
100 100 100 100 100 100 100 100 100 100 pre-stretch), 4X 100 100 100 100 
100 100 100 100 100 100 Heat Shock Test Temp., .degree.C. 175 200 175 
200 200 200 260 260 260 260 Burnout (F.O.M.) 5.4 6.67 8.51 2.46 
1.13 Heat Aging (hrs.) 168-OK ELECTRICAL PROPERTIES Dielectric Strength, 
dry 14.6 15.6 15.9 11.5 (vpm), wet 11.1 11.1 14.5 11.2 Dissipatio 
n Factor 11.5 4.92 3.34 3.16 5.45 28.72 22.26 453.0 1874.0 CHEMICAL 
PROPERTIES A. O. Smith Freon Test; appearance/flexibility Fail OK/OK 
dielectric after test (VPM) 
Compara- Compara- Compara- Compara- tive tive tive tive Exam- Exam- 
Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- ple ple ple ple 
ple ple ple ple ple ple ple 9 10 11 12 13 14 15 1 2 3 4 
Basecoat PEI PEI PEI PEI PEI PEI PEI PE PEI PEI PEI PE Build (mils) 
bondcoat/basecoat 1.0/2.0 1.0/2.0 1.0/2.0 1.0/2.1 1.0/2.1 1.0/2.1 
1.0/2.1 1.0/2.0 1.0/2.0 1.0/2.0 1.0/2.1 1.0/2.0 Wire Size (AWG) 18 18 18 
18 18 18 18 18 18 24 18 18 Wire Speed (fpm) 50 50 50 50 50 50 50 50 50 
90 50 50 Appearance, bondcoat/basecoat Wavy/ VSW/ VSW/ VSW-/ SW/ Hvy. 
Grain/ Hvy. Grain/ VSW-/ VSW-/ SW/ VSW-/ SW/ VSW VSW VSW+ VSW VSW VSW 
VSW VSW VSW VSW VSW VSW MECHANICAL PROPERTIES Mandrel, before snap 1X 
1X 1X 1X 1X 1X 1X 1X 1X 1X 1X Snap (OK or Fail) Fail OK OK OK OK OK OK 
OK OK OK OK OK Mandrel, after snap -- 1X 1X 1X 1X 1X 1X 1X 1X 1X 1X 1X 
Abrasion (gms.) -- 1833 1808 1708 1950 2000+ 2000+ 2000+ 1916 1000+ 
1750 1608 Windability Helical Coil Bonding; Bond Temp., .degree.C. 200 
200 200 200 200 200 200 200 200 200 200 200 Bond Str., lbs. @ 25.degree. 
C. -- -- -- -- -- -- -- 0.0 0.0 4.7 22.4 21.7 150.degree. C. -- 
-- -- -- -- -- -- -- -- 0.8 11.0 180.degree. C. 0.4 6.2 2.8 1.25 
6.3 5.5 3.6 0.0 0.0 0.2 2.8 200.degree. C. -- -- -- -- -- -- -- 
-- -- -- 0.4 THERMAL PROPERTIES Cut Through Temp., .degree.C. 
280 285 334 315 395 Heat Shock, 1X 80 90 50 90 20 (1/2Hr. at 
test, 2X 90 100 70 100 30 Temp., 20%, 3X 100 100 80 100 40 
pre-stretch), 4X 100 100 100 100 40 Heat Shock Test Temp., 
.degree.C. 175 200 200 175 175 Burnout (F.O.M.) 5.97 
5.46 Heat Aging (hrs.) ELECTRICAL PROPERTIES Dielectric Strength, dry 
11.1 (vpm), wet Dissipation Factor CHEMICAL PROPERTIES A. O. 
Smith Freon Test; appearance/flexibility OK/OK dielectric after test 
(VPM) 
It is critical to use terephthalic acid in copolyamides of the invention. 
Thus if in place of terephthalic acid there is used isophthalic acid in 
whole or in part as taught by Onder U.S. Pat. No. 4,072,665, the bond 
strength is reduced. 
Thus there were prepared copolyamides similar to Example 1 replacing the 
terephthalic acid in whole or in part by isophthalic acid. 
COMATIVE EXAMPLE 5 
The procedure was similar to Example 1 but there were used as reactants a 
70/30 molar ratio mixture of toluene diisocyanate and methylene 
diisocyanate and there was used a 65/25/10 molar mixture of dodecanedioic 
acid, isophthalic acid and terephthalic acid. 
COMATIVE EXAMPLE 6 
The procedure was the same as in Comparative Example 5 except the dibasic 
acids employed was 65/35 molar mixture of dodecanedioic acid and 
isophthalic acid. 
Examples 1 and 3 which are within the present invention both employ a 65/35 
molar mixture of dodecanedioic acid and terephthalic acid. The bond 
strength of Comparative Example 5, Comparative Example 6, Example 1, and 
Example 3 were tested by coating their resultant enamel solutions on top 
of ISOMID-coated wire at 50 ft./min., followed by bonding at 200.degree. 
C. for 20 minutes under 1-kg load. The results were as set forth in Table 
2: 
TABLE 2 
______________________________________ 
Test Bond Strength, 
Specimen Lbs. at 180.degree. C. 
______________________________________ 
Comparative Example 5 
4.75 
Comparative Example 6 
3.2 
Example 1 5.9 
Example 3 6.2 
______________________________________ 
It can be seen from Table 2 that the greater the replacement of 
terephthalic acid by isophthalic acid the greater the reduction in bond 
strength.