Process for producing electric windings

Electric machine windings produced by wrapping a composite insulating material around an electrical conductor, said composite insulating material having been prepared by bonding two or more insulating materials with a silicone resin containing hydroxyl groups in the molecular structure, impregnating said composite insulating material with an insulating varnish comprising 1 equivalent of a polyfunctional epoxy compound and 2.5 to 25 equivalents of a polyfunctional isocyanate compound and curing said varnish, have excellent insulation properties under high temperatures and high humidity and thermal resistance of class H or more.

This invention relates to a process for producing electric machine 
windings, more particularly to a process for producing highly moisture 
resistant and heat resistant electric windings having excellent insulation 
properties even under high humidity and high temperatures. 
Recently, in electric machines such as rotary machines, etc., highly 
moisture resistant and heat resistant electric windings having excellent 
insulation properties even under high humidity and high temperatures have 
been demanded with the enlargement of capacity or miniaturization and 
weight saving of electric machines, or with the use of electric machines 
under severe conditions. In order to meet such demands, there have been 
studied electric windings having thermal resistance of class H to class C 
by combining insulating materials obtained by bonding heat resistant 
materials such as glass tape, mica tape, polyimide tape, polyamide tape, 
etc. each other by using heat resistant resin adhesives such as polyimide 
resins, polyamide resins, silicone resins, diphenyl ether resins, epoxy 
resins, etc. with heat resistant resin insulating varnishes such as 
polyimide resins, silicone resins, epoxy resins, etc. But, there have not 
been developed electric windings having thermal resistance corresponding 
to class C. Among various combinations mentioned above, electric windings 
having the most excellent thermal resistance can be obtained in the case 
of using silicone resins. But in such a case, there is much room for 
improving mechanical strength and moisture resistance of silicone resins 
themselves. 
It is an object of this invention to provide a process for producing highly 
moisture resistant and heat resistant electric windings having thermal 
resistance of class H to class C and excellent moisture resistance, 
overcoming disadvantages of conventional windings as mentioned above. 
This invention provides a process for producing an electric winding which 
comprises 
wrapping a composite insulating material around an electrical conductor, 
said composite insulating material having been obtained by bonding two or 
more insulating materials with a silicone resin containing hydroxyl groups 
in the molecular structure, 
impregnating said composite insulating material with an insulating varnish 
comprising 1 equivalent of a polyfunctional epoxy compound and 2.5 to 25 
equivalents of a polyfunctional isocyanate compound, and 
curing the resulting impregnated composite insulating material. 
In electric machine windings, when one or more very small voids are 
generated in the insulating layer or layers, degradation of the material 
around the voids is accelerated by corona discharge. At the same time, a 
decomposed gas is generated due to the degradation and is expanded to 
increase inner pressure, which results in peeling of insulating layers and 
lowering in insulation properties. The degree of lowering in such a case 
becomes greater when the winding is used under extremely high temperatures 
such as in the case of that having thermal resistance of class C. 
Therefore, it is necessary to use an insulating material having 
particularly excellent properties in impregnation with a varnish. In order 
to meet such a requirement, special composite insulating materials such as 
a combination of glass tape and mica sheet, a combination of a polymer 
sheet having imide rings in the molecular structure and mica sheet, etc. 
are used in this invention, also taking thermal resistance of the 
materials into consideration. 
On the other hand, from the viewpoint of wrapping workability of the 
composite insulating material around an electrical conductor, the 
composite insulating material should be formed in one piece and should be 
excellent in flexibility. In order to meet such requirements, selection of 
adhesives for bonding at least two insulating materials for forming 
composite insulating materials is very important in this invention. 
Further, said adhesives should prevent the generation of very small voids 
which cause peeling of insulating layers of the winding. In order to 
satisfy these requirements, silicone resin containing hydroxyl groups in 
the molecular structure (hereinafter referred to as "silicone resin 
containing hydroxyl groups") is used in this invention. 
Silicone resins containing hydroxyl groups are different from addition 
polymerization type silicone resins in that the former can adhere two or 
more insulating materials very strongly and thus is effective for 
preventing the resulting laminated insulating materials from peeling due 
to insufficient adhesive strength. Further, the silicone resins containing 
hydroxyl groups have good thermal resistance due to having siloxane 
linkages in the main molecular chain, so that the generation of decomposed 
gas due to degradation is very little, which results in scarcely causing 
peeling of laminated insulating material layers due to accumulation of the 
decomposed gas in the laminated insulating material layers. In addition, 
since the silicone resins containing hydroxyl groups have remarkably 
larger gas permeability coefficient due to their molecular structure 
comparing with other organic materials, even if there is generated a gas 
due to degradation, it can easily be released out of the insulating layer 
system and there hardly takes place peeling of laminated insulating 
materials due to the accumulation of the decomposed gas in the laminated 
insulating material layers. Still further, the most important thing in 
using the silicone resins containing hydroxyl groups is that the hydroxyl 
groups in the silicone resins can easily be reacted with the isocyanate 
moieties of epoxy-isocyanate series resins used as an insulating varnish 
for impregnation to form a strong and tough insulating layer by combining 
the insulating materials and the insulating varnish uniformly in one 
piece. According to the results of thermal resistance tests, no sufficient 
result can be obtained for electric windings produced by using, as 
adhesive for bonding two or more insulating materials, heat resistant 
adhesives such as addition polymerization type silicone resins containing 
no hydroxyl group, polyimide resins, polyamide resins, diphenyl ether 
resins, etc. 
As the insulating materials for forming the composite insulating materials, 
there can be used glass insulating materials commercially available such 
as glass tape, and the like, mica sheet commercially available, polymer 
sheet containing imide rings in the molecular structure such as polyimide 
film, polyamideimide film, etc. Among them, a combination of glass tape 
and mica sheet, e.g. glass tape-backed mica sheet, etc., and a combination 
of polymer sheet containing imide rings in the molecular structure and 
mica sheet, e.g. polyimide film or polyamideimide film-backed mica sheet, 
etc. are preferable. 
As the mica sheet, that obtained in the form of sheet from soft or hard 
mica without calcination or with calcination can preferably be used. 
As the polymer containing imide rings in the molecular structure, there can 
be used a reaction product of a tetracarboxylic acid anhydride and a 
diamine, a reaction product of a tetracarboxylic acid anhydride and a 
diisocyanate, a reaction product of bisphthalimide or bismaleimide and a 
diamine, a reaction product of bisphthalimide or bismaleimide and a vinyl 
compound, and the like. As the polyamideimide, there can be used a 
reaction product obtained by reacting a reaction product of an excess 
primary diamine and a dicarboxylic acid chloride, with a tetracarboxylic 
acid anhydride, a reaction product obtained by reacting a reaction product 
of a tetracarboxylic acid anhydride and an excess diamine, with a 
dicarboxylic acid chloride, a reaction product of a primary diamine and 
trimellitic acid anhydride, and the like. There can also be used 
polyesterimide compounds which can be obtained from a reaction product of 
trimetallitic acid anhydride with a diol as a precursor using the same 
procedure as mentioned in the case of obtaining the polyamideimide 
compounds. Among these polymers containing imide rings, from the 
viewpoints of availability, workability and physical and chemical 
properties, etc., Kapton (a polyimide film manufactured by E. I. du Pont 
de Nemours & Co.), Pifron II (a polyamideimide film manufactured by 
Hitachi Chemical Co., Ltd.) and the like can preferably be used. 
As the silicone resin containing hydroxyl groups, there can be used that 
obtained by conventional processes, e.g. by formulating silanes 
represented by the formulae, RSiX.sub.3, R.sub.2 SiX.sub.2 and R.sub.3 
SiX, wherein R is hydrogen, an alkyl group such as methyl, ethyl, etc., an 
aromatic group, such as phenyl, tolyl, etc.,; and X is halogen or a group 
which can be hydrolyzed such as alkoxy, in a desired composition depending 
on objects, hydrolyzing the resulting composition with addition of water, 
carrying out partial dehydration condensation of the hydroxyl groups 
bonded to silicon atoms in the presence of heat or a catalyst, and 
increasing degree of polymerization to a proper value. 
These silicone resins containing hydroxyl groups are available 
commercially. For example, there can preferably be used silicone resins 
KR-275 (hydroxyl group content 0.5-1% by weight), KR-272 (hydroxyl group 
content 2% by weight), KR-214 (hydroxyl group content 4% by weight) and 
KR-216 (hydroxyl group content 6% by weight), all of them being 
manufactured by Shin-etsu Silicone Co., Ltd., together with amine compound 
catalysts such as triethanolamine, etc. or organometallic salt catalysts 
such as zinc octoate, etc. It is preferable to use silicone resins 
containing hydroxyl groups in an amount of 0.5% by weight or more and more 
preferably 6% by weight or less. The silicone resins can be used alone or 
as a mixture of two or more of them. Too high hydroxyl group contents make 
the silicone resins solid at room temperature, so that too high hydroxyl 
group content is not preferable from the viewpoint of workability. 
The amount of silicone resin containing hydroxyl groups to be coated on 
insulating materials, e.g. mica sheet, is not limited particularly, but 
from the viewpoints of workability, impregnation properties with varnish, 
and properties of electric windings, it is preferable to use 1 to 35% by 
weight of the silicone resin based on the total weight of the silicone 
resin and the insulating materials, e.g. mica sheet and glass type. 
The composite insulating material can be prepared by a conventional method. 
The composite insulating material is wrapped around an electrical 
conductor using a conventional method. 
Subsequently, the wrapped composite insulating material is impregnated with 
the insulating varnish comprising a polyfunctional epoxy compound and a 
polyfunctional isocyanate compound with special proportions. 
As the polyfunctional epoxy compound used in the present invention, there 
can be used bifunctional epoxides such as, for example, diglycydylether of 
bisphenol A, butadiene diepoxide, 
3,4-epoxycyclohexylmethyl-(3,4-epoxy)-cyclohexane carboxylate, 
vinylcyclohexene dioxide, 4,4'-di(1,2-epoxyethyl)diphenylether, 
4,4'-di(1,2-epoxyethyl)biphenyl, 2,2-bis(3,4-epoxycyclohexyl)propane, 
diglycidyl ether of resorcinol, diglycidyl ether of phloroglucinol, 
diglycidyl ether of methylphloroglucinol, bis(2,3-epoxycyclopentyl)ether, 
2-(3,4-epoxy)cyclohexane-5,5-spiro(3,4-epoxy)-cyclohexane-m-dioxane, 
bis(3,4-epoxy-6-methylcyclohexyl)adipate, 
N,N'-m-phenylenebis(4,5-epoxy-1,2-cyclohexanedicarboxyimide) and the like; 
and tri- or more functional epoxy compounds such as triglycidyl ether of 
p-aminophenol, polyallylglycidyl ether, 1,3,5-tri(1,2-epoxyethyl)benzene, 
2,2',4,4'-tetraglycidoxybenzophenone, tetraglycidoxytetraphenylethane, 
polyglycidyl ether of phenol-formaldehyde novolac, triglycidyl ether of 
glycerol, triglycidyl ether of trimethylolpropane and the like. With 
respect to the other epxoy compounds, a book entitled "Epoxy Resins" 
(American Chemical Society, 1970) written by Henry Lee and a book entitled 
"Handbook of Epoxy Resin" (McGraw Hill Book Co., 1967) written by Henry 
Lee and K. Neville contain the descriptions of the resins. 
Among the aforesaid polyfunctional epoxides, the diglycydylether of 
bisphenol A and the polyglycydylether of phenol-formaldehyde novolac have 
a particular good reactivity. Therefore, they are useful compounds. 
Further, the halides of these compounds can be used, too. 
As the polyfunctional isocyanate compounds, there can be used bifunctional 
isocyanates, such as, for example, methane diisocyanate, 
butane-1,1-diisocyanate, ethane-1,2-diisocyanate, butane-1,2-diisocyanate, 
transvinylene diisocyanate, propane-1,3-diisocyanate, 
butane-1,4-diisocyanate, 2-butene-1,4-diisocyanate, 
2-methylbutane-1,4-diisocyanate, pentane-1,5-diisocyanate, 
2,2-dimethylpentane-1,5-diisocyanate, hexane-1,6-diisocyanate, 
heptane-1,7-diisocyanate, octane-1,8-diisocyanate, 
nonane-1,9-diisocyanate, decane-1,10-diisocyanate, dimethylsilane 
diisocyanate, diphenylsilane diisocyanate, 
.omega.,.omega.'-1,3-dimethylbenzene diisocyanate, 
.omega.,.omega.'-1,4-dimethylbenzene diisocyanate, 
.omega.,.omega.'-1,3-dimethylcyclohexane diisocyanate, .omega., 
.omega.'-1,4-dimethylcyclohexane diisocyanate, 
.omega.,.omega.'-1,4-dimethylbenzene diisocyanate, 
.omega.,.omega.'-1,4-dimethylnaphthalene diisocyanate, 
.omega.,.omega.'-1,5-dimethylnaphthalene diisocyanate, 
cyclohexane-1,3-diisocyanate, cyclohexane-1,4-diisocyanate, 
dicyclohexylmethane-4,4'-diisocyanate, 1,3-phenylene diisocyanate, 
1,4-phenylene diisocyanate, 1-methylbenzene-2,4-diisocyanate, 
1-methylbenzene-2,5-diisocyanate, 1-methylbenzene-2,6-diisocyanate, 
1-methylbenzene-3,5-diisocyanate, diphenylether-4,4'-diisocyanate, 
diphenylether-2,4-diisocyanate, naphthalene-1,4-diisocyanate, 
naphthalene-1,5-diisocyanate, biphenyl-4,4'-diisocyanate, 
3,3'-dimethylbiphenyl-4,4'-diisocyanate, 
2,3'-dimethoxybiphenyl-4,4'-diisocyanate, 
diphenylmethane-4,4'-diisocyanate, 
3,3'-dimethoxydiphenylmethane-4,4'-diisocyanate, 
4,4'-dimethoxydiphenylmethane-3,3'-diisocyanate, 
diphenylsulfide-4,4'-diisocyanate, diphenylsulfone-4,4'-diisocyanate and 
the like; and trifunctional or more isocyanates, such as, for example, 
polymethylenepolyphenylisocyanate, triphenylmethanetriisocyanate, 
tris(4-isocyanatephenyl)thiophosphate), 
3,3',4,4'-diphenylmethanetetraisocyanate and the like. 
Further, dimers and trimers of the foregoing polyisocyanates are useful. 
The dimers and trimers are terminated by free isocyanate groups and 
contain one or more isocyaurate ring or uretdione ring, or both. Methods 
of preparing various kinds of trimers and uretdiones are disclosed in U.S. 
Pat. No. 3,494,888; U.S. Pat. No. 3,108,100; and U.S. Pat. No. 2,977,370, 
etc. 
Liquid polyisocyanates are also useful to obtain varnishes of the 
compositions. Among the liquid polyisocyanates preferable are mixtures of 
a polyisocyanate and carbodiimide polyisocyanates disclosed in German 
Offenlegungsschrift No. 2,601,927; Belgian Pat. No. 678,773; German 
Offenlegungsschrift No. 1,904,575; W. Neuman, P. Fischer: Angewandte 
Chemide, vol. 74, p. 803 (1962); F. Kurzer, K. Douraghi-Zadahi: Chemical 
Review, vol. 67, pp. 110-120 (1967); U.S. Pat. No. 3,657,161; U.S. Pat. 
No. 3,157,662; U.S. Pat. No. 2,491,983; U.S. Pat. No. 3,426,025; U.S. Pat. 
No. 3,406,198; etc. The carbodiimide polyisocyanates are represented by 
the general formula: 
EQU OCN--R--N.dbd.C--N--.sub.n R--NCO 
wherein R is a residue of a polyisocyanate and n is an integer of not less 
than one, preferably one to four. 
The proportions of the epoxy compound and the isocyanate compound in the 
insulating varnish should be within limited ranges in order to impart 
excellent thermal resistance to the cured article. Said proportions are 
2.5 to 25 equivalents of the isocyanate compound per equivalent of the 
epoxy compound. If the proportions are outside the above-mentioned range, 
the resulting cured article has no good balance in weight loss by heating, 
electrical properties, mechanical properties, etc., which may result in 
lowering in insulation properties of the electric winding. 
In order to form isocyanurate rings and oxazolidone rings in the molecular 
structure by reacting the epoxy compound and the isocyanate compound in 
the insulating varnish with heating, it is necessary to use a hetero ring 
forming catalyst. As these catalysts, organic compounds having at least 
one atom selected from the elements belonging to the group Va in the 
periodic table in the molecule are useful. 
Examples of suitable catalysts are tertiary amines such as trimethylamine, 
triethylamine, tetramethylbutanediamine, tetramethylpentanediamine, 
tetramethylhexanediamine, triethylenediamine, N,N-dimethylaniline, etc.; 
oxyalkylamines such as dimethylaminoethanol, dimethylaminopentanol, etc.; 
amines such as tris(dimethylaminomethyl)phenol, N-methylmorpholine, 
N-ethylmorpholine, etc.; quaternary ammonium salts such as 
cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, 
dodecyltrimethylammonium iodide, trimethyldodecylammonium chloride, 
benzyldimethyltetradecylammonium chloride, benzyldimethylpalmitylammonium 
chloride, allyldodecyltrimethylammonium bromide, 
benzyldimethylstearylammonium bromide, benzyldimethyltetradecylammonium 
acetate, etc.; imidazoles such as 2-methylimidazole, 2-ethylimidazole, 
2-undecylimidazole, 2-heptadecylimidazole, 2-methyl-4-ethylimidazole, 
1-butylimidazole, 1-propyl-2-methylimidazole, 1-benzyl-2-methylimidazole, 
1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 
1-cyanoethyl-2-phenylimidazole, 
1-(4,6-diamino-s-triazinyl-2-ethyl)-2-ethylimidazole, 
1-(4,6-diamino-s-triazinyl-2-ethyl)-2-phenylimidazole, 
1-(4,6-diamino-s-triazinyl-2-ethyl)-2-isopropylimidazole, 
2-phenylimidazole, 1-(4,6-diamino-s-triazinyl-2-ethyl)-2-ethylimidazole, 
1-(4,6-diamino-s-triazinyl-2-ethyl)-2-methylimidazole, 
1-(4,6-diamino-s-triazinyl-2-ethyl)-2-undecylimidazole, etc.; 
tetra-substituted borate type compounds of phosphorus, arsenic, antimony 
and bismuth such as 
______________________________________ 
##STR1## 
##STR2## 
##STR3## 
##STR4## 
##STR5## 
##STR6## 
______________________________________ 
wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.6 are independently 
hydrogen, an alkyl group having 1 to 5 carbon atoms, an alkenyl group 
having 2 to 6 carbon atoms, a phenyl group, or a substituted phenyl group 
such as a C.sub.1-4 alkyl-substituted phenyl group, a C.sub.1-4 
alkoxy-substituted phenyl group, and R.sub.5 is a phenyl group, or a 
substituted phenyl group such as a C.sub.1-4 -alkyl-substituted phenyl 
group, a C.sub.1-4 alkoxy-substituted phenyl group. 
Among them, those having nitrogen oxide or phosphorus are particularly 
useful from the viewpoints of availability and workability. 
These catalyst are preferably used in an amount of 0.001 to 10.0% by weight 
based on the weight of the insulating varnish. If the amount of the 
catalyst is outside the above-mentioned range, the resulting cured article 
shows a tendency to become brittle or to generate a gas due to thermal 
degradation much more. 
In some cases, the catalyst for the insulating varnish may be mixed with 
the silicone resins containing hydroxyl groups and added to the insulating 
materials prior to the impregnation with the insulating varnish. In such 
cases, it is very important for improving properties of the resulting 
electric winding to conduct a condensation reaction of the silicone resin 
with heating at a temperature not to decompose the catalyst thermally and 
at the same time not to lower flexibility of the composite insulating 
tape. This is because if the condensation reaction of the silicone resin 
is conducted in the insulating layers of the electric winding, there will 
be formed very small voids due to the generation of condensation water in 
the insulating layers, degradation of the materials around the voids will 
be accelerated by corona discharge in such portions, and gas generated by 
the degradation will expand and increase the inner pressure so as to cause 
peeling between the insulating layers and to lower insulation properties 
of the winding. Therefore, it is preferable to cure the silicone resin 
which bonds the insulating materials with heating at a temperature of 
80.degree. to 160.degree. C.

This invention is illustrated in more detail by way of the following 
Examples in which all parts and percents are by weight unless otherwise 
specified. 
EXAMPLES 1 TO 3 
(1) Preparation of a composite insulating material 
Glass-backed mica tape of 25 mm wide was prepared by piling uncalcined soft 
mica sheet on glass tape, coating a toluene or xylene solution of silicone 
resin containing hydroxyl groups (hydroxyl group content 2%; KR-272 
manufactured by Shin-etsu Silicone Co., Ltd.) therebetween so that the 
amount of the silicone resin as a solid became 15% based on the total 
weight, and cutting superfluous portions. Zinc octoate as a curing 
catalyst was included in the silicone resin in an amount of 1% together 
with 2-ethyl-4-methylimidazole (2E4MZ) (manufactured by Shikoku Kasei Co., 
Ltd.) as a curing catalyst for an insulating varnish in an amount as 
listed in Table 1. The glass-backed mica tape was dried at 
80.degree.-160.degree. C. for 15 hours with heating. 
(2) Preparation of an insulating varnish 
An insulating varnish of epoxy-isocyanate series for impregnation was 
prepared by mixing 100 parts of a bisphenol series diglycidyl ether 
(DER-332 manufactured by Dow Chemical Co., epoxy equivalent 175) and 200, 
400 or 800 parts of liquid diphenylmethane diisocyanate (Desmodur CD 
manufactured by Bayer A. G., isocyanate equivalent 140). 
(3) Production of electric winding 
The composite insulating material prepared in the above-mentioned (1) was 
wrapped around a bare electric conductor. The resulting winding was vacuum 
impregnated under pressure with the insulating varnish prepared in the 
above-mentioned (2) and then cured at 100.degree.-150.degree. C. for 20 
hours and at 200.degree.-220.degree. C. for 4 hours with heating. 
Moisture resistance and thermal resistance of the resulting windings were 
tested in the following two ways. 
(A) Moisture resistance and thermal resistance test 
A sample was heated at 270.degree. C. for 24 hours and subsequently was 
placed under the conditions of a temperature of 40.degree. C. and a 
relative humidity of 95% for 24 hours. This procedure was defined as one 
cycle and repeated for 10 times. Each end of each cycle, dielectric loss 
tangent (tan .delta.) and insulation resistance were measured. The results 
are as shown in Table 1. 
(B) Short time thermal resistance test 
A specimen of 50.times.50 mm was cut out of the insulating layer of the 
electric winding mentioned above and heated at 270.degree. C. for 10 days 
to measure a weight loss due to thermal degradation. The results are as 
shown in Table 1. 
EXAMPLE 4 
(1) Preparation of a composite insulating material 
Glass-backed mica tape was prepared in the same manner as described in 
Example 1 except for using a silicone resin containing hydroxyl groups 
(hydroxyl group content 4%; KR-214 manufactured by Shin-etsu Silicone Co., 
Ltd.) and 4.0 parts of 1-cyanoethyl-2-phenylimidazole (2PZ-CN) 
(manufactured by Shikoku Kasei Co., Ltd.) as a curing catalyst for an 
insulating varnish. 
(2) Preparation of an insulating varnish 
An epoxy-isocyanate series insulating varnish was obtained by mixing 70 
parts of DER-332, 30 parts of a novolac type polyglycidyl ether (DEN-431 
manufactured by Dow Chemical Co., epoxy equivalent 175) and 1200 parts of 
Desmodur CD. 
(3) Production of electric winding 
Using the materials prepared in the above items (1) and (2), an electric 
winding was produced in the same manner as described in Example 1 (3). 
The same tests as described in Example 1 were conducted. The results are 
listed in Table 1. 
EXAMPLE 5 
(1) Preparation of a composite insulating material 
Glass-backed mica tape of 25 mm wide was prepared by piling uncalcined soft 
mica sheet on glass tape, coating a solution of silicone resin mixture 
prepared by mixing KR-216 (hydroxyl group content 6%, manufactured by 
Shin-etsu Silicone Co., Ltd.) and KR-272 (hydroxyl group content 2%) with 
a mixing ratio of 2:1 by weight therebetween so that the amount of the 
silicone resins as a solid became 15% based on the total weight, and 
cutting superfluous portions. 2PZ-CN as a curing catalyst for an 
insulating varnish was also included in the silicone resin mixture in an 
amount of 4.0 parts together with 1% of zinc octoate as a curing catalyst. 
The glass-backed mica tape was dried at 80.degree.-160.degree. C. for 15 
hours with heating. 
(2) Preparation of an insulating varnish 
An epoxy-isocyanate series insulating varnish was obtained by mixing 70 
parts of DER-332, 20 parts of DEN-431, 10 parts of novolac type 
polyglycidyl ether (DEN-438 manufactured by Dow Chemical Co., epoxy 
equivalent 178) and 2000 parts of Desmodur CD. 
(3) Production of electric winding 
Using the materials prepared in the above items (1) and (2), an electric 
winding was produced in the same manner as described in Example 1 (3). 
The same tests as described in Example 1 were conducted. The results are 
listed in Table 1. 
EXAMPLES 6 TO 9 
(1) Preparation of a composite insulating material 
Glass-backed mica tape of 25 mm wide was prepared by piling uncalcined soft 
mica sheet on glass tape, coating a solution of silicone resin containing 
hydroxyl groups (hydroxyl group content 0.5-1.0%; KR-275 manufactured by 
Shin-etsu Silicone Co., Ltd.) therebetween so that the amount of the 
silicone resin as a solid became 15% based on the total weight, and 
cutting superfluous portions. The glass-backed mica tape was dried at 
80.degree.-160.degree. C. for 15 hours with heating except for Example 9. 
As a curing catalyst for the silicone resin, 1% of zinc octoate was used 
in Example 6 and 1% of triethanolamine was used in Examples 7 to 9, while 
3.0 parts of 2E4MZ was used as a curing catalyst for an insulating varnish 
in Examples 6 to 9. But in Example 8, 2E4MZ was not added to the silicone 
resin but to the insulating varnish. 
(2) Preparation of an insulating varnish 
An epoxy-isocyanate series insulating varnish was obtained by mixing 100 
parts of DER-332, and 800 parts of liquid diphenylmethane diisocyanate 
(Desmodur CD). But in Example 8, the curing catalyst 2E4MZ was added to 
the insulating varnish. 
(3) Production of electric winding 
Using the materials prepared in the above items (1) and (2), an electric 
winding was produced in the same manner as described in Example 1 (3). 
The same tests as described in Example 1 were conducted. The results are 
listed in Table 1. 
EXAMPLES 10 TO 12 
(1) Preparation of a composite insulating material 
Polyimide film-backed mica tape of 25 mm wide was prepared by piling 
calcined hard mica sheet on polyimide sheet (Kapton, a registered 
trademark of E. I. du Pont de Nemours & Co.), coating a solution of 
silicone resin containing hydroxyl groups (hydroxyl group content 2%; 
KR-272) therebetween so that the amount of silicone resin as a solid 
became 10% in Example 10, 20% in Example 11, and 30% in Example 12, based 
on the total weight, and cutting superfluous portions. The polyimide 
film-backed mica tape was dried at 80.degree.-160.degree. C. for 15 hours 
with heating. As a curing catalyst for the silicone resin, 1% of zinc 
octoate was used and as a curing catalyst for an insulating varnish, 
2PZ-CN was used in an amount as listed in Table 1. 
(2) Preparation of an insulating varnish 
An epoxy-isocyanate series insulating varnish was obtained by mixing 
Desmodur CD and DER-332 and in Example 10 together with DEN-431 in amounts 
as listed in Table 1. 
(3) Production of electric winding 
Using the materials prepared in the above items (1) and (2), an electric 
winding was produced in the same manner as described in Example 1 (3). 
The same tests as described in Example 1 were conducted. The results are 
listed in Table 1. 
EXAMPLES 13 TO 15 
(1) Preparation of a composite insulating material 
Polyimide film-backed mica tape of 25 mm wide was prepared by piling 
calcined hard mica sheet on polyimide sheet (Kapton), coating a solution 
of silicone resin containing hydroxyl groups (hydroxyl group content 
0.5-1.0%; KR-275) therebetween so that the amount of the silicone resin as 
a solid became 15% based on the total weight, and cutting superfluous 
portions. The polyimide film-backed mica tape was dried at 
80.degree.-160.degree. C. for 15 hours except for Example 15. As a curing 
catalyst for the silicone resin, 1% of zinc octoate was used in Example 13 
and 1% of triethanolamine was used in Examples 14 and 15, while as a 
curing catalyst for an insulating varnish, 4.5 parts of 
(4,6-diamino-s-triazinyl-2-ethyl)-2-undecylimidazole (C.sub.11 Z-AZINE) 
(manufactured by Shikoku Kasei Co., Ltd.) was added to the silicone resin. 
(2) Preparation of an insulating varnish 
An epoxy-isocyanate series insulating varnish was prepared in the same 
manner as described in Example 6 (2). 
(3) Production of electric winding 
Using the materials prepared in the above items (1) and (2), an electric 
winding was produced in the same manner as described in Example 1 (3). 
The same tests as described in Example 1 were conducted. The results are 
listed in Table 1. 
EXAMPLE 16 
(1) Preparation of a composite insulating material 
Polyamideimide film-backed mica tape of 25 mm wide was prepared by piling 
calcined hard mica sheet on polyamideimide sheet (Pifron II manufactured 
by Hitachi Chemical Co., Ltd.), coating a solution of silicone resin 
containing hydroxyl groups (hydroxyl group content 0.5-1.0%; KR-275) 
therebetween so that the amount of the silicone resin as a solid became 
15% based on the total weight, and cutting superfluous portions. The 
polyamideimide film-backed mica tape was dried at 80.degree.-160.degree. 
C. for 15 hours. As a curing catalyst for the silicone resin, 1% of 
triethanolamine was added and as a curing catalyst for an insulating 
varnish, 4.5 parts of C.sub.11 Z-AZINE was added to the silicone resin. 
(2) Preparation of an insulating varnish 
An epoxy-isocyanate series insulating varnish was prepared in the same 
manner as described in Example 6 (2). 
(3) Production of electric winding 
Using the materials prepared in the above items (1) and (2), an electric 
winding was produced in the same manner as described in Example 1 (3). 
The same tests as described in Example 1 were conducted. The results are 
listed in Table 1. 
COMATIVE EXAMPLE 1 
(1) Preparation of a composite insulating material 
Glass-backed mica tape of 25 mm wide was prepared in the same manner as 
described in Example 1 (1) except for using as a curing catalyst for an 
insulating varnish 2PZ-CN as used in Example 4 (1). 
(2) Production of electric winding 
The procedure described in Example 1 (3) was repeated except for using an 
insulating varnish containing 100 parts of DER-332 and 120 parts of 
Desmodur CD for producing an electric winding. 
The same tests as described in Example 1 were conducted. The results are 
listed in Table 1. 
COMATIVE EXAMPLE 2 
(1) Preparation of a composite insulating material 
Glass-backed mica tape of 25 mm wide was prepared in the same manner as 
described in Comparative Example 1 (1). 
(2) Production of electric winding 
The procedure described in Example 1 (3) was repeated except for using an 
insulating varnish containing 100 parts of DER-332 and 2400 parts of 
Desmodur CD for producing an electric winding. 
The same tests as described in Example 1 were conducted. The results are 
listed in Table 1. 
COMATIVE EXAMPLE 3 
(1) Preparation of a composite insulating material 
Polyimide film-backed mica tape of 25 mm wide was prepared in the same 
manner as described in Example 13 (1) except for using as a curing 
catalyst for an insulating varnish 2PZ-CN as used in Example 4 (1). 
(2) Production of electric winding 
The procedure described in Example 1 (3) was repeated except for using an 
insulating varnish as used in Comparative Example 1 (2) for producing an 
electric winding. 
The same tests as described in Example 1 were conducted. The results are 
listed in Table 1. 
COMATIVE EXAMPLE 4 
Polyimide film of 25 mm wide (Kapton) was wrapped around a bare conductor. 
The resulting winding was vacuum impregnated under pressure with the same 
insulating varnish as used in Example 2 except for containing 4.5 parts of 
2PZ-CN. Then the same procedure as described in Example 1 (3) was repeated 
in order to produce an electric winding. 
The same tests as described in Example 1 were conducted. The results are 
listed in Table 1. 
COMATIVE EXAMPLE 5 
(1) Preparation of a composite insulating material 
Glass-backed mica tape of 25 mm wide was prepared by piling uncalcined soft 
mica sheet on glass tape, coating a heat resistant epoxy resin (DEN-438 
manufactured by Dow Chemical Co., epoxy equivalent 178) therebetween so 
that the amount of the epoxy resin became 15% based on the total weight, 
and cutting superfluous portions. 
(2) Preparation of an insulating varnish 
An insulating varnish was prepared by mixing 400 parts of Desmodur CD, 100 
parts of DER-332 and 4.5 parts of 2PZ-CN as in the case of Comparative 
Example 4. 
(3) Production of electric winding 
Using the materials prepared in the above items (1) and (2), an electric 
winding was produced in the same manner as described in Example 1 (3). 
The same tests as described in Example 1 were conducted. The results are 
listed in Table 1. 
COMATIVE EXAMPLE 6 
The glass-backed mica tape used in Example 7 was wrapped around a bare 
conductor and impregnated under reduced pressure with a solventfree 
addition polymerization type silicone resin (KR-2019, Shin-etsu Silicone 
Co., Ltd.) containing 1.5 parts of dicumyl peroxide per 100 parts of the 
resin as a polymerization catalyst. The impregnated insulating varnish was 
cured at 160.degree. C. for 15 hours and at 200.degree. C. for 15 hours to 
produce an electric winding. 
The same tests as described in Example 1 were conducted. The results are 
listed in Table 1. 
As is clear from the results shown in Table 1, the electric windings 
produced by wrapping the composite insulating materials prepared by 
bonding, for example, mica sheet to glass sheet or polyimide or 
polyamideimide or the like polymer sheet by using silicone resins 
containing hydroxyl groups in the molecular structure and impregnating the 
wrapped composite insulating materials with epoxy-isocyanate series 
insulating varnishes having special compositions are remarkably superior 
to those produced in Comparative Examples 5 and 6 in moisture resistance 
and thermal resistance. The properties of windings can be improved further 
by using composite insulating materials dried with heating prior to 
wrapping around conductors. In Comparative Example 4, since mica sheet is 
not used as insulating material, the insulating varnish is insufficiently 
impregnated into the insulating layers. In Comparative Example 5, although 
the epoxy resin adhesive having thermal resistance of class H is used, the 
generation of gas cannot be prevented and the gas thus generated cannot be 
released out of the insulating layers and causes peeling of the insulating 
layers due to highly increased inner pressure of the generated gas in the 
layers. Further the results of Comparative Examples 1 and 2 show that if 
the proportions of the polyfunctional epoxy compound and the 
polyfunctional isocyanate compound are outside the special range, moisture 
resistance and thermal resistance of the windings are lowered due to 
decreases of properties of the cured articles. 
As mentioned above, according to this invention, insulated electric machine 
windings having excellent insulation properties under high temperatures 
and high humidity comparing with those obtained by a conventional method 
can be produced. 
Table 1 
__________________________________________________________________________ 
Example No. 1 2 3 4 5 6 7 
__________________________________________________________________________ 
AdhesiveSilicone resin 
KR-272 
KR-272 
KR-272 
KR-214 
KR-272 
KR-275 
KR-275 
KR-216 
Zn octoate 1.0 1.0 1.0 1.0 1.0 1.0 -- 
Catalyst 
(wt. %)Triethanol- 
-- -- -- -- -- -- 1.0 
amine 
Adhesive content (wt. %) 
15 15 15 15 15 15 15 
Insulating material 
G-U G-U G-U G-U G-U G-U G-U 
Drying with heating 
Done Done Done Done Done Done Done 
Desmodur CD 200 400 800 1200 2000 800 800 
Insulat-DER-332 100 100 100 70 70 100 100 
ingDEN-431 -- -- -- 30 20 -- -- 
varnishDEN-438 -- -- -- -- 10 -- -- 
(parts)NCO eq. ratio 
2.5/1 
5/1 10/1 
15/1 
25/1 5/1 5/1 
Catalyst2E4MZ 3.0 3.0 10 -- -- 3.0 3.0 
2PZ-CN -- -- -- 4.0 4.0 -- -- 
C.sub.11 Z-AZINE 
-- -- -- -- -- -- -- 
Properties 
Initialtan .delta. (%) 
1.8 1.6 1.2 1.4 1.9 1.2 1.2 
MoisturetimeMeg. (M.OMEGA.) 
.infin. 
.infin. 
.infin. 
.infin. 
.infin. 
.infin. 
.infin. 
andAfter 5tan .delta. (%) 
11.4 8.3 8.2 9.3 10.9 10.0 9.3 
thermalcyclesMeg. (M.OMEGA.) 
.infin. 
.infin. 
.infin. 
.infin. 
.infin. 
.infin. 
.infin. 
resist-After 10tan .delta. (%) 
8.8 8.3 6.1 8.3 8.5 8.5 7.3 
ancecyclesMeg. (M.OMEGA.) 
.infin. 
.infin. 
.infin. 
.infin. 
.infin. 
.infin. 
.infin. 
Weight loss (%), 270.degree. C./10 days 
8.1 7.2 6.8 6.5 6.3 6.9 7.1 
__________________________________________________________________________ 
(Note) 
G-U: Glassbacked mica tape, 
K-U: Polyimide filmbacked mica tape, 
P-U: Polyamideimide filmbacked mica tape 
- 
Example No. 8 9 10 11 12 13 14 15 16 
__________________________________________________________________________ 
Silicone resin KR-275 
KR-275 
KR-272 
KR-272 
KR-272 
KR-275 
KR-275 
KR-275 
KR-275 
Zn octoate -- -- 1.0 1.0 1.0 1.0 -- -- -- 
Triethanolamine 1.0 1.0 -- -- -- -- 1.0 1.0 1.0 
Adhesive content 
15 15 10 20 30 15 15 15 15 
Insulating G-U G-U K-U K-U K-U K-U K-U K-U P-U 
material 
Drying Done None Done Done Done Done Done None Done 
Desmodur CD 800 800 400 800 2000 400 400 400 400 
DER-332 100 100 50 100 100 100 100 100 100 
DEN-431 -- -- 50 -- -- -- -- -- -- 
DEN-438 -- -- -- -- -- -- -- -- -- 
NCO eq. ratio 5/1 5/1 5/1 10/1 25/1 5/1 5/1 5/1 5/1 
2E4MZ 3.0* 3.0 -- -- -- -- -- -- -- 
2PZ-CN -- -- 3.0 4.5 10 -- -- -- -- 
C.sub.11 Z-AZINE 
-- -- -- -- -- 4.5 4.5 4.5 4.5 
Properties 
Initial tan .delta. (%) 
1.3 1.9 1.1 1.2 1.4 1.1 1.2 1.4 1.2 
time Meg (M.OMEGA.) 
.infin. 
.infin. 
.infin. 
.infin. 
.infin. 
.infin. 
.infin. 
.infin. 
.infin. 
After 5 tan .delta. (%) 
8.2 11.3 11.0 11.3 12.0 10.5 10.1 12.1 11.1 
cycles Meg (M.OMEGA.) 
.infin. 
800 .infin. 
.infin. 
.infin. 
.infin. 
.infin. 
.infin. 
.infin. 
After tan .delta. (%) 
6.3 12.5 10.7 12.3 13.2 9.6 9.8 14.0 10.0 
10 
cycles Meg (M.OMEGA.) 
.infin. 
.infin. 
.infin. 
.infin. 
.infin. 
.infin. 
.infin. 
.infin. 
.infin. 
Weight loss (%) 7.2 9.8 6.0 6.6 7.0 6.2 6.1 8.3 7.6 
__________________________________________________________________________ 
(Note) 
*The catalyst was added to the insulating varnish. 
Comparative Example No. 
1 2 3 4 5 6 
__________________________________________________________________________ 
Silicone resin KR-272 
KR-272 
KR-272 
(Epoxy 
(Epoxy 
KR-275 
resin) 
resin) 
AdhesiveZn octoate 
1.0 1.0 1.0 -- -- -- 
Catalyst 
(wt. %)Triethanol- 
-- -- -- -- -- 1.0 
amine 
Adhesive content (wt. %) 
15 15 15 -- 15 15 
Insulating material 
G-U G-U K-U K G-U G-U 
Drying with heating 
Done Done Done None None Done 
Desmodur CD 120 2400 120 400 400 
InsulatingDER-332 varnish (parts) 
100 100 100 100 100 
##STR7## 
NCO eq. ratio 1.5/1 
30/1 1.5/1 
5/1 5/1 
Catalyst 2PZ-CN 1.5 10 1.5 4.5* 4.5* 
Properties 
Initial 
tan .delta. (%) 
2.2 2.1 1.9 3.2 1.2 2.1 
Moisture 
time Meg. (M.OMEGA.) 
.infin. 
.infin. 
.infin. 
.infin. 
.infin. 
.infin. 
and After 5 
tan .delta. (%) 
18.6 17.5 19.1 18.0 21.0 18.5 
thermal 
cycles 
Meg. (M.OMEGA.) 
500 500 500 500 100 100 
resist- 
After 10 
tan .delta. (%) 
17.5 19.3 18.9 20.0 21.9 19.7 
ance cycles 
Meg. (M.OMEGA.) 
80 80 80 80 5 5 
Weight loss (%), 270.degree. C./10 days 
10.1 9.4 11.6 18.6 20.6 6.8 
__________________________________________________________________________ 
(Note) 
K:Polymide tape 
*:The catalyst was added to the insulating varnish.