Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~Z~4~ RD-163~4
RD 15364
.
,
FLAME RETARDANT WIRE COATING CO~OSITIONS
BACKGROUND OF_THE INVENTION
Prior to the present invention, as shown by Holub,
U.S. Patent 3,325,450, polysiloxane imides useful as insula-
tion for electrical conductors were prepared by effecting
reaction between a diaminopolysiloxane and benzophenonedi-
anhydride in the presence of a suita~le organic solvent,
such as dimethylformamide, N-methyl-2-pyrrolidone, cresol,
etc. The initial reaction was generally carried out from
room temperature to 150C resulting in the production of an
intermediate polyamide acid derivative. Thereafter, the
solvent was removed from the resulting amide acid derivative
by heating at temperatures of from about 150~C to 400DC to
effect cyclization and formation of the imide structure.
A similar procedure is shown by Greber, Polykon-
densationsreaktionen Bifunktioneller Siliciumorganischer
Verbindungen, Journal fur praktische Chemie. Band 313, HEFT
3, 1971, S. 461-483, J.A. Barth, Leipzig. Although the
procedure of Greber is somewhat different from that shown by
Holub, both Holub and Greber utilize a dipolar aprotic
solvent, such as dimethylacetamide to form a solution of a
silicone-polyamide acid from which films can be cast onto a
--1-- ~ ..
RD-15364
~Z7~8
substrate and further heating is required to effect the
cyclization of the polyamide acid to the polyimide state.
Improved results in methods for making silicone-
pol~imides can be obtained by utilizing aromatic bis(ether
a~hydride) or the corresponding tetracarboxylic acid in
combination with amino alkylene terminated polydiorgano-
siloxanes as shown, for example, by Takekoshi et al., U.S.
Patent 3,833,546 and Heath et al., U.S. Patent 3,847,867,
assigned to the same assignee as the present invention.
Although silicone-polyimides have long been
recognized for their potential as a source for extrudable
wire coating insulation, the flammability requirements o~
the wire çoating industry has generally restricted the use
of these materials. In addition to flame retardance, wire
coating fabricators also favor extrudable wire coating
insulation having at least 150% elongation at break when
pulled-laterally from a clamped portion of the extrudate
along the wire surface. However, efforts to increase the
elongation characteristics of silicone-polyimide by increas-
ing the weight percent of silicone has generally been foundto increase the flammability of the silicone-polyimide.
The present invention is based on a discovery that
silicone-polyimide utili7ing aromatic bis(ether anhydride)
and amino alkylene termi~ated polydiorganosiloxane having a
critical block length can be extruded onto wire and exhibit
an elongation percent of 150 or greater-while satisfying UL
94 flammability requirements as defined hereinafter. Wire
coating industry requirements can be satisfied providing a
critical relationship is maintained between the polydior-
ganosiloxane block length and the weight percen' siliconewhich is preferably 25% to 45% by weight based on the weight
of silicone-polyimide. Polydiorganosiloxane block lengths
having an average value of about 20 diorganosiloxy units or
RD-16364
~7~6~
less has been found to provide effective results, while a
block length of about 5 to about 15 chemically combined
diorganosiloxy units is preferred.
As used hereinafter, the expressions "flame
resistance", "flammable", "nonflammable" or "flame retar-
dance" with respect to silicone-polyimide means that the
silicon -polyimide has satisfied UL 94 ~-0 requirements for
flammability as shown by the Flammability of Plastic Materi-
als Bulletin of January 24, 1980. More particularly, a 5" x
1/2" x 1/8" silicone-polyimide test bar was suspended
vertically over a 3/4" Bunsen burner flame as provided in
the aforementioned UL 94 test. The test sample exhibited a
~4 V-0 rating, which includes the following criteria:
A. Not have any specimens which burn with
flaming combustion for more than 10 seconds
after either application of the test flame.
B. Not have a total flaming combustion time
exceeding 50 seconds for the 10 flame appli-
cations for each set of five specimens.
C. Not have any specimens which burn with
flaming or glowing combustion up to the
holding clamp.
D. Not have any specimens which drip flaming
particles that ignite the dry absorbent
surgical cotton located 12 inches (305 mm)
below the test specimen.
E. Not have any specimens- with glowing combus-
tion which persists for more than 30 seconds
after the second removal of the test flame.
The silicone polyimides of the present invention
can be made by effectin~ reaction between amine terminated
polydiorganosiloxane having the formula
RD-1635~
~Z7~
( 1 ) NH~-R~iO)~i-R~ 2
and organic dianhydrides, as defined hereinafter, where R is
a C(l 14) monovalent hydrocarbon radical or substituted
C(l 14) monovalent hydrocarbon radical, Rl is a C(l 14)
: divalent hydrocarbon radical or substituted C(l 14) divalent
hydrocarbon radical, and n is an integer having an average
value of from about 3 to 20 inclusive, and preferably 5 to
15. Rl is preferably C(l 4) polymethylene.
STAT~MENT OF THE INVENTION
There is provided by the present invention,
extrudable, flame retardant, silicone-polyimide copolymer
comprising by weight,
(A) from about 40 to 90% of chemically combined
arylimide blocks and
(B) from about 10 to 50% of chemically combined
polydiorganosiloxane blocks consisting essentially of from
about 3 to about 20 diorganosiloxy units, where the organo
radicals attached to silicone are selected from monovalent
C(l 14) hydrocarbon radicals and substituted monovalent
C(1-14) hYdrCarbon radicals.
Chemically combined arylimide blocks which can be
present in the silicone-polyimide compositions of the
present invention are included within the formula,
RD-16364
~74~4~3
~/ <~
where R2 is selected from Rl radicals, or the same or
different C~l 14) monovalent hydrocarbon radicals and
substituted C(l 14) monovalent hydrocarbon radicals, Q i~ a
tetravalent radical selected from
, and
~ D
D is a member selected from
-O-, -S~ NRlN~ oR30~- and
-OR Q- -
and R3 is a divalent radical selected from
P~-16364
~7~
~H3
~ . ~r, r~
CH3 H3
~3~ ~ 3
C 3 r BrCH3
~r Br
CtCH3)
Br r
and divalent organic radicals of the general formula,
,:
X is a member selected from the cl~ss consisting of divalent
radicals of the formula,
c ~ ~ 3 o and -S-
p is 0 or 1, y is ~n integer equal to l to 5 inclusive and m
is an intPger equal to from 1 to about 60 inclusive.
~7~4~ h~-16364
.~mong the preferred arylimide included within
formula (2) there is included aryletherimide of the formula
(3) -N ~ o_R4_o ~ _
where R4 is a di~alent aryl radical selected from the class
consisting of
CH3 CH3 CH3 CH3 CH3
- CH3 CH3
C~3Br ~rlH3 Br Br
)
CH3Br BrCH3 Br r
and
~}~xl~
xl is a member selected from the class consisting of
RD-1~354
~LZ7~
yH2y ~ ~, -O- and -S-
and p and y are as previously deined.
Radicals included within K of formula (1~ are, for
example, C(l 8~ alkyl radicals such as methyl, ethyl,
propyl, butyl, pentyl, etc.; C(6 13) aryl radicals such as
phenyl, tolyl, xylyl, anthryl; halogenated alkyl and aryl
radicals such as chlorophenyl; cyanoalkyl radicals, for
example, cyanoethyl, cyanobutyl, trifluoropropyl, etc.
Radicals included within Rl and R2 of formulas (1) and ~2
are, for example, C(l 8) alkylene radicals such as methy-
lene, dimethylene, trimethylene, tetramethylene, etc. and
arylene radicals such as phenylene, tolylene, xylene,
naphthalene, etc.
Organic anhydrides which can be utilized in the
practice of the present invention are preferably aromatic
bis(etheranhydride)s which are included within the formula,.
(4) ~ I ~ oR40 ~ ~ ~
where R4 is as previously deined. Some of the dianhydriàes
included within formula (4~ are, for example,
2,2'-bis~4-(2,3-dicarboxyphenoxy)phenyl]propane
dianhydride;
4,4'-bis(2,3-dicarboxyphenoxy~diphenyl ether
dianhydride;
- ~D-16364
~Z7~6~1~
1,3-bis(2,3-dicarboxyphenoxy)benzene dianhydride;
4,4'~bis)2,3 dicarboxyphenoxy)diphenyl sulfide
dianhydride;
1,4-bis~2,3-dicarboxyphenoxy)benzene dianhydride;
4,4'-bis(2,3-dicarboxyphenoxy~diphenylsulfone
dianhydride, etc.;
2,2-bis[4-(3,4~dicarboxyphenoxy)phenyl]propane
dianhydride;
4,4'-bis(3,4-dicarboxyphenoxy)diphenyl ether
dianhydride;
4,4'-bis(3,4-dicarboxyphenoxy)diphenyl sulfide
dianhydride;
l,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride;
1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride;
4,4'-bis(3,4-dicarboxyphenoxy)diphenylsulfone
dianhydride;
4-(2,3-dicarboxyphenoxy)-4'(3,4-dicarboxyphenoxy)-
2,2-diphenylpropane dianhydride, etc.
The dianhydrides of formula (4) can be made in
accordance with Webb, U.S. Patent 4,116,980, assigned to the
same assignee as the present invention.
In addition to the preferred aromatic bis(ether
anhydrides) of formula (4), there can be used other organic
dianhydrides in combination with such aromatic bis(ether
anhydrides) to make the silicone-polyimide wire coating
compositions of the present invention. These organic
dianhydrides can be used at up to 50 mole percent based on
total dianhydride and include pyromellitic dianhydrides,
benzophenone dianhydride and 5,5'-(1,1,3,3-tetramethyl-
1,1,3-disiloxanedilyl-bis-norbornane-2,3-dicarboxylic
dianhydride.
Procedures for making the aminoorgano terminated
polydiorganosiloxane of formula (l) are well known in the
RD-16364
l;Z7g~4~
art. For example, aminoorganotetraorganodisiloxane can be
eguilibrated with an octaorganocyclotetrasiloxane, such as
octamethylcyclotetrasiloxane, to increase the block length
of the polydiorganosiloxane. The corresponding aminoorgano-
tetraorganodisiloxane, such as aminobutyltetramethyldisilox-
ane can be made by the procedure shown by Prober, U.5.
Patent 3,185,719, assigned to the same assignee as the
present invention. Prober reacts allylcyanide with di-
methylchlorosilane and then hydrolyzes the resulting cyano-
propyldimethylchlorosilane in the presence of sodium bicar-
bonate to produce the l,3-bis-~ cyanopropyltetramethyl-
disiloxane which then can be reduced with hydrogen in the
presence of Raney nickel to yield 1,3-bis-~-aminobutyltetra-
methyldisiloxane. In a similar manner, 1,3-aminopropyl
terminated polydimethyIsiloxane can be obtained by the
equilibration of 1,3-bis-~-aminopropyltetramethyldisiloxane
which is prepared by utilizing acrylonitrile in a manner
similar to that shown for the production of aminobutyltetra-
methyldisiloxane utilizing allylcyanide.
In addition to the aminoorganopolydiorganosiloxane
in formula (1), there can be utilized in making the sili-
cone-polyimides of the present invention, up to about 90
mole percent of aryldiamines based on the total moles of the
aminoorganopolydiorganosiloxane of formula (1) and such
aryldiamines having the formula
- where R5 is a divalent C(6 14) arylene radical.
Included within the arylamines of formula (5) are,
for example,
m-phenylene diamine;
p-phenylenediamine;
--10-
~D-16364
4~
4,4'-diaminodiphenylpropane;
4,4-diaminodiphenylmethane;
benzidine;
4,4'-diaminodiphenyl sulfide;
4,4'-diaminodiphenyl sulfone;
4,4'-diaminodiphenyl ether;
1,5'-diaminonaphthalene;
3,3'-dimethylbenzidine;
3,3'-dimethoxybenzidine;
2,4-bis(~-amino-t-butyl)toluene;
bis(p-~-amino-t-butylphenyl)ether;
bis(p-~-methyl-o-aminopentyl)benzene;
l,3'-diamino-4-isopropylbenzene;
1,2-bis(3-aminopropoxy)ethane;
m-xylylenediamine;
p-xylylenediamine;
2,4-diaminotoluene;
2,6-diaminotoluene.
In instances where aryldiamine of formula (5) is
used in combination with the aminoorgano terminated polydi-
organosiloxane of formula (l), the weight percent of the
aryldiamine is included in the weight percent of the aryl-
imide.
The silicone-polyimides can be made by effecting
reaction between the organic anhydride, which hereinafter
means aromatic bis(ether anhydride) of formula (4) or a
mixture thereof with other organic anhydrides, and amino
polydiorganosiloxane which hereinafter will mean the amino-
organo terminated polydiorganosiloxane of formula (l), or a
mixture thereof with aryldiamine of formula (5) in a suit-
able organic solvent. Some of the organic solvents which
can be used are, for example, dipolar aprotic solvents, such
as dimethylformamide, N-methyl-2-pyrrolidone, cresol,
--11--
RD-16364
~Z7g~
orthodichlorobenzene, etc. In general, there can be used
from about 0.9 to 1.1 mole of the amine functional groups in
the terminal position on the aminoorgano terminated polydi-
organosiloxane, per mole of the anhydride functional groups
of the organic anhydride.
The initial amino-organic anhydride reaction can
be carried out from about 100C to 390~C. Reaction can
continue until the water of reaction produced during the
copolymerization of the organic anhydride and the amino-
organo terminated polydiorganosiloxane is achieved and tnewater of reaction is completely removed such as by azeotrop-
ing from the reaction mixture. There can be used a typical
polymerization catalyst at 0.025 to 1.0% by weight, based on
the weight of the reaction mixture, such as an alkali metal
aryl phosphinate or alkali metal aryl phosphonate, for
example, sodium phenylphosphonate.
At the completion of the polymerization reaction,
the silicone-polyimide can be isolated by diluting the
reaction mixture with a material such as chloroform to
reduce the solids level to about 10% and reprecipitating the
resulting mixture in an organic solvent such as isopropanol.
The resulting product can thereafter be dried by convention-
al means such as a vacuum oven.
The silicone-polyimides of the present invention
are valuable as wire coating compositions and can be extrud
ed onto metallic conductors such as aluminum or copper wire
to thicknesses up to 50 mil. During the polymerization
reaction, a chain-stopper, such as a monofunctional aromatic
anhydride or monofunctional aromatic amine, for example,
aniline or phthalic anhydride, can be used if desired to
control the molecular weight of the silicone-polyimide.
In order that those skilled in the art will be
better able to practice the present lnvention, the following
-12-
P~-163~
~LZ~4~
examples are given by way of illustration and not by way of
limitation. All parts are by weight unless otherwise speci-
fied.
ExamPle 1
A series of 3-aminopropyldimethylsiloxy terminated
polydimethylsiloxanes were prepared having an average of
from about 8 to about 30 dimethylsiloxy units. The proce-
dure for making a 3-aminopropyl terminated polydimethyl-
siloxane having an average of about 9.5 dimethylsiloxy units
was as follows:
A mixture of 102.52 moles of bis-(3-aminopropyl)-
tetramethyldisiloxane and 230.66 moles of octamethylcyclo-
tetrasiloxane and 1.0 moles of tetramethylammonium hydroxide
was stirred at a temperature of about 80C for 6 to 8 hours
under a nitrogen atmosphere. The equilibration was monitor-
ed by gas chromatography. When the equilibration was
completed, the temperature was raised to 150~C to effect
catalyst decomposition and devolatilization of from 10-15%
by weight of low molecular cyclics. The mixture was aliowed
to cool to room temperature and then titrated for amine end
groups with standardized perchloric acid in acetic acid
using methyl violet at the indicator. There was obtained a
3-aminopropyldimethylsiloxy polydimethylsiloxane having an
average of about 9.5 dimethylsiloxy units and a molecular
weight of about 949.13 per chain.
A silicone-polyimide was prepared in accordance
with the following procedure:
A mixture of 7.502 grams of 2,2-bis[4-(3,4-dicar-
boxyphenoxy)phenyl]propane dianhydride, 0.17B grams of
phthalic anhydride, 0.811 grams of metaphenylenediamine,
6.173 grams of a 3-aminopropyldimethylsiloxy terminated
-13
RD-16354
31 Z~ 8
polydimethylsiloxane having an average of 7.7 dimethylsilsxy
units per chain, 40 ml. of orthodichlorobenzene and 0.004
gram of sodium phenylphosphinate was heated under a positive
nitrogen pressure at 140C for 1 hour. Solvent and water
were removed from the reaction mixture until a total of
about 15 ml. of orthodichlorobenzene was collected resulting
in a reaction mixture having about 30% solids. The mixture
was refluxed for an additional 4 hours and then allowed to
cooL. The cooled reaction mixture was diluted with 25 ml.
of chloroform and poured with vigorous stirring into 250 ml.
of isopropanol. A product was isolated by filtration and
washed with copious quantities of isopropanol. The result-
ing solid was dried for at least 4 hours at 120-150C in a
vacuum oven. The dried solid was then redissolved in
chloroform (to 15% solid) and again reprecipitated into
isopropanol. There was obtained 11.4 grams for an 81% yield
of a silicone-polyimide after drying in a vacuum oven.
Based on method of preparation the resulting silicone-poly-
imide consisted essentially of polyimide having 42% by
weight of polydimethylsiloxane blocks having an average of
about 7.3 dimethylsiloxy units.
Several additional silicone polyimides were
prepared from a 3-aminopropyl dimethylsiloxy terminated
polydimethylsiloxane having an average of about 15 dimethyl-
siloxy units. These silicone polyimides varied over a
wei~ht percent range of 29-48 of chemically combined poly-
dimethylsiloxane based on weight of silicone-polyimide.
Tensile elongations were determined from extruded strands
obtained from dried polymer charged to a Tinius-Olsen
Extrusion Plastometer heated to 275-320~C.
The results of those measurements are shown in
Figure 1 and in the following table:
-14-
~D-16~64 .
12~4~
Table I
Effect of Wt% Dimethylsiloxane
, On Percent Elongation
Wt~ Siloxane ~ Elongation
29 25
33 50
36 100
42 200
48 300
10 The above results show that percent elongation is
dependent on the weight percent of diorganosiloxane in
silicone-polyimide.
Example 2
The procedure of Example 1 was repeated to provide
: 15 several silicone-polyimides with polydimethylsiloxane blocks
having from about 8-30 chemically combined dimethylsiloxy
units. The silicone-polyimides were evaluated for elonga-
tion and flammability in accordance with UL-94 as shown in
Figure 2 and the following table:
Table II
Flammability and Percent Elongation
of Silicone-Polyimide
SiloxaneWt% UL-94
BlockDiorgano- Flame Out*
25 LengthSiloxane% Elongatio~ Time (sec)
9.5 37 200 21
11 42 230 48
37 25 28
46 190 45
57 200 '50 sec
~Flame out time (FOT) average for 10 ignitions
-15-
RD-1~364
~'~7~69~
.
The above results show that silicone-polyimide
wire coating compositions having an average block length of
from about 8 to about 20 dimethylsiloxy units, can provide a
percent elsngation of at least 150%, while satisfying the
V-O requirements of less than 50 seconds FOT for an average
of 10 ignitions. An average block length of about 30
required too much chemically combined methylsiloxane to
achieve a satisfactory degree of elongation which rendered
it flammable.
Example 3
In accordance with the procedure of Thames et al,
Journal of Organic Chemistry, A. Org. Chem. 1975, 40, 1090,
there was prepared 3-bromo-N,N~bis(trimethylsilyl)aniline.
There was added 2.6 moles of butyl lithium in
hexane over a 15 minute period to a mixture of 50 grams of
the 3 bromo-N,N-bis(trimethylsilyl)aniline in 400 ml. of
anhydrous ether cooled to 0C under a nitrogen atmosphere.
The resulting reaction mixture was allowed to stir for an
additional 2 hours at 0~C. The mixture was then added to a
mixture of 100 ml. of anhydrous ether and 16.06 grams of
1,3-dichloro-1,1,3,3-tetramethyldisiloxane at 0C. After
the solution was filtered and the solvents were removed
under reduced pressure, there was obtained a 77% yield of
1,3-bis[N,N-bis(trimethylsilyl)-3-aminophenyl]-1,1,3,3-tetr-
amethyldisiloxane in the form of a pale-yellow oil having a
boiling point of about 169-174C.
A mixture of 38 grams of the above-bis-substituted
trimethylsilylaminophenyltetramethyldisiloxane, 30 grams of
methanol, 100 milligrams of p-toluene sulfonic acid monohy-
drate and 300 ml. of anhydrous ether was stirred for 12
hours at room temperature. The resulting etherial solution
-1~-
~27~ RD-16364
was washed with two 100 ml. portions of a saturated sodium
bicarbonate solution and then with 100 ml. of brine. The
organic phase was dried over anhydrous magnesium sulfate,
filtered and the solvents were removed under reduced pres-
sure. There was obtained a 90% yield of a pale-yellow oil
after vacuum distillation of the crude product which had a
boiling point of 169-174C. Based on method of preparation
and NMR spectra, the product was 1,3-bis(m-aminophenyl)-
1,1,3,3-tetramethyldisiloxane.
A mixture of 4.8 grams of the above 1,3-bis(m-
aminophenyl)-1,1,3,3-tetramethyldisiloxane, 22.48 grams of
octamethylcyclotetrasiloxane and 30 milligrams of powdered
potassium hydroxide was heated at 150~C for 12 hours under a
nitrogen atmosphere. The temperature was lowered to 120C
and 68 milligrams of sodium bicarbonate was added. The
reaction mixture was stirred for 1 hour at 120C and then
cooled to 90C. The reaction mixture was diluted with 100
ml. of toluene. After an additional heating for 30 minutes
at 90~C, the solution was cooled to room temperature and
filtered. There was obtained a yellow oil. Based on method
of preparation, IR spectra and NMR spectra the resulting
product was a polysiloxanediamine. Based on the average
molecular weight of the isolated material (20.6 grams
determined by titration) the average length of the poly-
siloxane was found to be sufficient to provide a value of n
of about 19-21.
A mixture of 16.84 grams of the above aminophenyl
terminated polydimethylsiloxane and 4.636 grams of 2,2-bis-
[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride dis-
solved in 40 ml. of orthodichlorobenzene along with 0.0012
yram of sodium phenylphosphinate. The resulting reaction
mixture was heated for 1.5 hours at 140C and then brought
to reflux. Water was removed over a 2 hour period and then
-17-
RD-16364
1~74~
the mixture was refluxed for an additional 18 hours. A
material was isolated by diluting the polymerization reac-
tion mixture with chloroform to reduce the solids level to
10%. A product was obtained by reprecipitating the result-
ing solids in isopropanol. There was obtained a polymerwhich was dried in a vacuum oven at 210C for 18 hours. The
product was a rubbery-like light-brown material having a
glass transition temperature below room temperature and an
IV of 1.4.
Example 4
The procedure of Example 3 was repeated, except
that m-phenylenediamine was also used in the polymerization
mixture. There was utilized 1.5674 grams of m-phenylenedia-
mine, 8.1222 grams of the abo~e aminophenyl terminated
polydimethylsiloxane, 10.032 grams of the aromatic bis(ether
anhydride), 0.0034 grams of sodium phenylphosphinate and 40
ml. of orthodichlorobenzene. The resulting product was less
flexible than the silicone-polyetherimide containing the
silicone blocks having an average value of 19-21 dimethyl-
siloxy units. It exhibited a glass transition temperature
at about 184C. However, it had significantly superior
flexibility as compared to polyetherimide resin resulting
from the polymerization of m-phenylenediamine and the
aromatic bis(ether anhydride) free of the aminophenyl
terminated siloxane.
Exam~le 5
The procedure of Example 3 was repeated to make a
variety of silicone-polyimides. Some of the silicone-poly-
imides were based on the use of polydimethylsiloxane having
-18-
~7~ RD-l53~4
terminal aminophenyldimethylsiloxy units, while other
silicone-polyimides were based on the use of polydimethyl-
siloxane having terminal aminopropyldimethylsiloxy units.
In addition, the aminoorgano terminated polydimethylsiloxane
was used in the form of a disiloxane and a polydimethylsi-
loxane having about 20 chemically combined dimethylsiloxy
units. A further silicone-polyimide was made utilizing
aromatic bis(ether anhydride) in accordance with Example 3
and difunctional amine material consistiny of a mixture o~
equal molar amounts of m-phenylenediamine and aminopropyl-
dimethylsiloxy terminated polydimethylsiloxane having about
20 chemically combined dimethylsiloxy units.
The above silicone-polyimides were then evaluated
for thermal stability utilizing TGA analysis. The following
results were obtained heating the respective silicone-poly-
imides in air at a heating rate of 10C/min. to determine
the temperature at which a 5% weight loss and 10% weight
loss were experienced, where ArSi(2) indicates the phenyl
substituted disiloxane containing silicone-polyetherimide
and ArSi(20) indicates the phenyl terminated polydimethyl-
siloxane containing silicone-polyetherimide, while GAPSi(2)
indicates the aminopropyldisiloxane containing silicone-
polyetherimide and GAPSi(20) indicates the aminopropyldi-
methylsiloxane containing silicone-polyetherimide:
Table III
Wt. Loss in Air (~C)
Silicone-~ol~etherimide
ArSi(2) 490 520
GAPSi(2) 463 470
ArSi(20) 430 4A5
GAPSi(20) 390 405
It was further found that the silicone-polyimide
having chemically combined m-phenylene units experienced a
--19--
~D-1~364
~74~
5% weight loss at 395 and a 10% weight loss at 410. This
data indicates that the silicone-polyimides obtained from
the use of aminophenyl terminated polydimethylsiloxane ha~e
significantly higher oxidative stability than the silicone-
polyimides derived from the use of aminopropyl terminatedpolydimethylsiloxane. In addition, the use of m-phenylene-
diamine in combination with aminopropyl terminated polydi-
methylsiloxane ~as found to enhance the oxidative stability
of the resulting silicone-polyimide.
ExamPle 6
An additional evaluation of the flexibility of the
silicone-polyetherimides of the present invention were made
having polydimethylsiloxane blocks of about 17 chemically
combined dimethylsiloxy units based on the use of aminopro-
pyldimethylsiloxy terminated polydimethylsiloxane. The fol-
lowing results were obtained, where "n" is the number of
dimethylsiloxy units in the silicone block, "Mol ~" indi-
cates the moles of dimethylsiloxy units in the silicone-
polyetherimide based on total moles of chemically combined
units, "MW" is the molecular weight of the silicone-poly-
etherimide and "Flex Mod" is the flexural modulus of the
silicone-polyetherimide:
Table IV
n Mol~ MW Flex Mod
25 17 5~ 97,200 22,000
17 20 71,000 59,000
17 15 65,000 150,000
17 10 59,200 250,000
The above results show that mole percent of
silicone diamine relative to the total moles of diamine used
-20-
RD-16364
12'~
in making the silicone-polyimide and molecular weight can
influence the flexural modulus.
Although the above examples are directed to only a
.few of the very many variables which can be u~ed in the
practice of the present invention to make the silicone-poly-
imide wire coating compositions, it should be understood
that the present invention is directed to a much broader
variety of aminoorganosiloxanes as shown by formula (1) and
organic dianhydride as illustrated by formula (4) where R
can be further defin~d as a divalent C(6 20) aromatic
- organic radical which are shown in the description preceding
these examples.
-21-
