Injection moldable amide-imide polymers and copolymers containing amorphous polyamides

Flow properties of polyamide-imide polymers are improved by the addition of amorphous polyamides. These polymers are useful as engineering resins, laminates, and molded objects.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The field of this invention relates to polyamide-imide polymers containing 
amorphous polyamides and to molding powders and molded articles prepared 
therefrom. 
2. Background 
Amide-imide polymers and copolymers are a relatively new class of organic 
compounds known for their solubility in nitrogen containing solvents when 
in the largely polyamide form. In the past the major application of these 
amide-imide polymers has been as wire enamels. This is illustrated in U.S. 
Pat. Nos. 3,661,832 (1972), 3,494,890 (1970) and 3,347,828 (1967). 
Amide-imide polymers and copolymers have also been found useful for 
molding applications as shown in U.S. Pat. Nos. 4,016,140 (1977) and 
3,573,260 (1971). U.S. Pat. Nos. 4,136,085 (1979), 4,313,868 (1982), and 
4,309,528 (1982) are incorporated herein by reference. These polyamides 
are known for their outstanding mechanical properties, but they are also 
difficult to process, particularly to injection mold. This difficulty is a 
consequence of insufficient flow of the polymer. The art has been looking 
for improvements in the flow and reduction in melt reactivity during 
fabrication of the polymers, but it is essential that an additive not 
impair the excellent mechanical properties of the polyamide-imide polymers 
and copolymers, particularly the flexural and heat deflection properties. 
The ideal flow improving agent for these polymers would be one which 
plasticizes the polymers during injection molding and cross-links links 
the polymers and copolymers during the curing or annealing step so that 
the plasticizing effect would be neutralized by cross-linking. 
The general object of this invention is to provide polyamide-imide polymers 
and copolymers containing amorphous polyamides. A more specific object of 
this invention is to provide polyamide-imide polymers and copolymers 
suitable for use as engineering plastics and high pressure laminates 
particularly for use in injection molding wherein the polymer flow is 
improved while its melt reactivity is hindered by the addition of up to 
about 20 percent by weight of amorphous polyamides. Other objects appear 
hereinafter. 
I have now found that amide-imide polymers and copolymers obtained by 
reacting a polycarboxylic acid anhydride with one primary diamine or a 
mixture of primary diamines containing up to 20 percent of amorphous 
polyamides have excellent flow properties and can readily be injection 
molded to provide engineering plastics with excellent properties but which 
can be produced or molded at a much faster rate since the polymer flow has 
been substantially increased when compared to the polymers which do not 
contain amorphous polyamides. The amorphous polyamides improve the flow 
and reduce the melt reactivity of neat or filled amide-imide polymers and 
also when glass fibers, glass beads, mineral fillers, graphite fiber or 
graphite powder are coated with the amorphous polyamide, these can more 
readily be incorporated into a molded amide-imide object. Amorphous 
polyamides have also been found to aid the manufacture of amide-imide 
impregnated graphite woven fiber laminates. Suitable amorphous polyamides 
have both aromatic and aliphatic moieties. Advantageously, the amorphous 
polyamide comprises recurring units of the following structure: 
##STR1## 
wherein Y is a straight chain of one to six methylene groups, said chain 
being substituted by at least one alkyl group, the total number of side 
chain carbon atoms introduced by the alkyl substitution being at least 
one. 
Another amorphous polyamide group suitable for use in improving the melt 
flow and reducing the melt reactivity of our amide-imide polymer has the 
following structure: 
##STR2## 
Amorphous polyamides of the following structure are preferred for use in 
our process, both for flow improvement and for coating the glass fibers, 
glass beads, mineral fillers or graphite fibers incorporated into a molded 
polyamide-imide object of this invention. 
The amorphous polyamide, Trogamid-T, manufactured by the Dynamit Nobel 
Company, has the following structure and is particularly useful in 
improving the flow properties and reducing the melt reactivity of the 
polyamide-imide: 
##STR3## 
wherein X is CH.sub.2. 
Another very useful amorphous polyamide is Amidel, manufactured by Union 
Carbide Company and having the following structure: 
##STR4## 
more particularly wherein the first X is (CH.sub.2).sub.7, the second X is 
CH.sub.2 and the third X is (CH.sub.2).sub.4. 
Other useful polyamides include the Upjohn amorphous polyamide of the 
following structure: 
##STR5## 
wherein the first X is (CH.sub.2).sub.9 and the second X is CH.sub.2, and 
the copolyamide of the following structure: 
##STR6## 
wherein X is (CH.sub.2).sub.6. 
In all of the foregoing structures X can be a straight chain of one to five 
CH.sub.2 groups. X can be the same or different in each amorphous 
polyamide moiety. 
FIG. 1 shows that the amide-imide resins of our invention are very reactive 
in that the cavity pressure can drop down about 14,000 psi to 0 psi after 
only a 20 to 30 second increase in cycle time. Particular attention is 
drawn to steep negative slopes of the control in FIG. 1. The control is an 
amide-imide polymer filled with 40 percent glass fibers prepared in 
Example II. When about 1 percent, 3 percent, and 5 percent of an amorphous 
polyamide were dry blended with our glass fiber filled amide-imide 
polymer, a drastic improvement in melt stability and flow occurred. This 
is clearly shown in FIG. 1, wherein the amorphous polyamide stabilized 
amide-imide was compared with the unstabilized amide-imide polymer. That 
Figure shows that a 110 percent improvement in flow occurred with the 5 
percent amorphous polyamide-imide blend with respect to the amide-imide 
control sample. Equally significant is that the amide-imide melt 
reactivity is reduced when the amorphous polyamide is added, thus the flow 
increased as the cycle time increased. This is clearly contrary to the 
behavior of an amide-imide polymer not containing amorphous polyamides. 
The same is shown in FIG. 2 where different amorphous polyamides are used. 
The amount of the amorphous polyamide added to the amide-imide polymer can 
be about 0.1 to 20 weight percent, usually in the range of about 0.1 to 
about 10 percent. The amorphous polyamide is miscible in our amide-imide 
polymers, thus forming a single glass transition (Tg) matrix. When 5 
weight percent of the amorphous polyamide such as Trogamid-T was dry 
blended with our amide-imide polymer (see Example I) and was molded, a 
single Tg was found. The Tg of our amide-imide polymer used as a control 
was 257.degree. C. as molded while the polymer containing 5 percent by 
weight of Trogamid-T had a glass transition temperature of about 
254.degree. C. After being cured at a temperature of 160.degree. C. to 
260.degree. C., the glass transition temperature for our control 
polyamide-imide polymer rose to 277.degree. C. and for the sample 
containing 5 percent Trogamid-T rose to 237.degree. C. An increase in Tg 
also occurred with amide-imide resin with glass fiber filler. For a 40 
percent glass filled resin as given in Example IX, the glass transition 
temperature increased by 43.degree. F. This clearly demonstrates that 
imidization and solid state polymerization occurred during post cure. The 
amorphous polyamides reduce the reactivity of our amide-imide polymer melt 
while allowing solid state polymerization during post cure. Thus, with 
these amorphous polyamides excellent post cure can be carried out and it 
is during this post cure that the excellent physical and thermal 
properties of our amide-imide polymer containing amorphous polyamides are 
obtained. 
Amide-imide materials build their properties during the annealing step such 
that as molded properties are significantly below the annealed properties 
as illustrated in Table 1 below. To build amide-imide properties, parts 
are annealed at temperatures up to about 530.degree. F. but preferably 
500.degree. F. Since the amorphous polyamides are miscible in the 
amide-imides, the blend Tg falls between the two constituents. It is 
important that the blend Tg is maintained above the maximum annealing 
temperature such that optimum properties can be built during annealing. It 
is also important that the blend Tg is above the maximum annealing 
temperatures so that part distortion due to stress relaxation does not 
occur. 
TABLE 1 
______________________________________ 
As Annealed 
Molded at 500.degree. F. 
______________________________________ 
% Glass Loading 40 40 
Injection Molding Temperatures 
600 600 
Physical Properties 
Tensile Strength (psi) 
13,500 33,600 
Tensile Elongation (%) 
1.7 4.2 
Tensile Modulus (psi) 
1,680,000 1,820,000 
HDT .degree.F. 479 546 
Izod Impact ft.-lbs. 0.92 1.14 
in. of notch 
______________________________________ 
After cure a representative 5 percent Trogamid-T neat amide-imide sample 
had total shrinkage of 8.7 mils per inch, while the control had a 
shrinkage of 7 mils per inch. 
It should be particularly emphasized that when our amides are blended with 
amorphous polyamides a one phase miscible amide-imide amorphous polyamide 
system is obtained. This is critical in the effectiveness of our process 
and our novel process and novel compositions since if a one phase miscible 
system is not formed, delamination of the incompatible components can 
readily occur with a multiphase polymer system. 
Amorphous polyamides coated on sized fillers such as glass fibers give 
better molding characteristics and higher cavity pressures. This allows 
for higher filler content without restricting the flow. Thus 
polyamide-imide polymers and copolymers, containing 20 to 60 percent 
filler can be marketed without loss of the excellent physical properties 
of our amide-imide polymers. The amorphous polyamide stabilized polymers 
of this invention are prepared by reacting an acyl halide derivative of an 
aromatic tricarboxylic-acid-anhydride with one or a mixture of largely- or 
wholly-aromatic primary diamines. The resulting products are polyamides 
wherein the linking groups are predominantly amide groups, although some 
may be imide groups, and wherein the structure contains free carboxylic 
acid groups which are capable of further reaction. Such polyamides are 
moderate molecular weight (7-13,000 as prepared) polymeric compounds 
having in their molecule units of: 
##STR7## 
wherein the free carboxyl groups are ortho to one amide group, Z is an 
aromatic moiety containing 1 to 4 benzene rings or lower-alkyl-substituted 
benzene rings; R.sub.1, R.sub.2 and R.sub.3 are the same for homopolymers 
and are different for copolymers and are divalent wholly- or 
largely-aromatic hydrocarbon radicals. These hydrocarbon radicals may be a 
divalent aromatic hydrocarbon radical of from 6 to about 10 carbon atoms, 
or two divalent aromatic hydrocarbon radicals each of from 6 to about 10 
carbon atoms joined directly or by stable linkages such as --O--, 
methylene, --CO--, --SO.sub.2 --, --S--; for example, --R'--O--R'--, 
--R'--CH.sub.2 --R'--, --R'--CO--R'--, --R'--SO.sub.2 --R'-- and 
--R'--S--R'--. 
Said polyamides are capable of substantially complete imidization by 
heating, by which they form the polyamide-imide structure having to a 
substantial extent reoccurring units of: 
##STR8## 
wherein one carbonyl group is meta to and one carbonyl group is para to 
each amide group and wherein Z, R.sub.1, R.sub.2 and R.sub.3 are defined 
as above. Typical copolymers of this invention have up to about 50 percent 
imidization prior to heat treatment, typically about 10 to about 40 
percent. 
Our process is also useful for improving the flow compositions of 
polyamide-imide of the foregoing composition wherein between about 20 to 
80 percent of imide-containing moieties are replaced by the following 
composition: 
##STR9## 
wherein R.sub.4 is the same as R.sub.1, R.sub.2 or R.sub.3 and X is a 
divalent aromatic radical. The preferred composition for X is 
##STR10## 
or a mixture of these. 
The polyamide-imide copolymers are prepared from an anhydride-containing 
substance and a mixture of wholly- or partially-aromatic primary diamines 
or fully or partially acylated diamines. The process using acylated 
diamines is disclosed in U.S. Pat. No. 4,309,528 incorporated herein by 
reference. Usefully the anhydride-containing substance is an acyl halide 
derivative of the anhydride of an aromatic tricarboxylic acid which 
contains 1 to 4 benzene or lower-alkyl-substituted benzene rings and 
wherein two of the carboxyl groups are ortho to one another. More 
preferably, the anhydride-containing substance is an acyl halide 
derivative of an acid anhydride having a single benzene or 
lower-alkyl-substituted benzene ring, and most preferably, the substance 
is the acyl chloride derivative of trimellitic acid anhydride (4-TMAC). Up 
to 80 percent of the dianhydride can be replaced by aromatic diacids such 
as terephthalic acid or isophthalic acid. The process is disclosed in U.S. 
Pat. No. 4,313,868, incorporated herein by reference. 
We can use a single diamine but usefully the mixture of diamines contains 
two or more, preferably two or three, wholly- or largely-aromatic primary 
diamines. More particularly, they are wholly- or largely-aromatic primary 
diamines containing from 6 to about 10 carbon atoms or wholly- or 
largely-aromatic primary diamines composed of two divalent aromatic 
moieties of from 6 to about 10 carbon atoms, each moiety containing one 
primary amine group, and the moieties linked directly or through, for 
example, a bridging --O--, --S--, --SO.sub.2 --, --CO--, or methylene 
group. When three diamines are used they are preferably selected from the 
class composed of: 
##STR11## 
said X being an --O--, --CH.sub.2 --, or --SO.sub.2 -- group. More 
preferably, the mixture of aromatic primary diamines is in the one 
component or two-component and is composed of meta-phenylenediamine and 
p,p'-oxybis(aniline) and meta-phenylenediamine, or 
p,p'-sulfonylbis(aniline) and p,p'-methylenebis(aniline). Most preferably, 
the mixture of primary aromatic diamines contains meta-phenylenediamine 
and p,p'-oxybis(aniline). In the one component system the preferred 
diamines are oxybis (aniline) or meta-phenylene diamine. The aromatic 
nature of the diamines provides the excellent thermal properties of the 
homopolymer copolymers while the primary amine groups permit the desired 
imide rings and amide linkages to be formed. 
Usually the polymerization or copolymerization is carried out in the 
presence of a nitrogen-containing organic polar solvent such as 
N-methylpyrrolidone, N,N-dimethylformamide and N,N-dimethylacetamide. The 
reaction should be carried out under substantially anhydrous conditions 
and at a temperature below about 150.degree. C. Most advantageously, the 
reaction is carried out from about 20.degree. C. to about 50.degree. C. 
The reaction time is not critical and depends primarily on the reaction 
temperature. It may vary from about 1 to about 24 hours, with about 2 to 4 
hours at about 30.degree. C. to 50.degree. C. preferred for the 
nitrogen-containing solvents. 
Cavity pressure measurements are used as quality control checks of 
polyamide-imide resin viscosity. Pressure buildup during the filling of an 
injection molded part is measured at a point in the cavity (ejector pin). 
This is accomplished by placing a pressure transducer behind the ejector 
pin and recording the pressure with a chart recorder or other readout 
device. Cavity pressure normally rises as the mold is being filled and 
peaks as the molten resin is packed into the cavity. As the resin 
solidifies, cavity pressure decreases. 
We have found that resins that have low cavity pressure process poorly and 
that spiral flow measurements were not sensitive enough to discriminate 
between resins in the viscosity range of interest. Low cavity pressures 
indicate a large pressure drop between injection and cavity pressures. 
This indicates higher resin viscosities. In the same manner high cavity 
pressures indicate less pressure change between injection and cavity 
pressures, suggesting lower resin viscosities. 
Amide-imide polymer and copolymer viscosities had been measured by spiral 
flow determinations previous to the implementation of the cavity pressure 
procedure, see U.S. Pat. No. 4,224,214. Cavity pressure was selected over 
spiral flow because of its greater sensitivity. The cavity pressure test 
has been implemented as an amide-imide homopolymer and copolymer quality 
control procedure. Like spiral flow, cavity pressure is a test that can be 
done conveniently in a molder's shop. 
The injection molding machine was equipped with a horizontally mounted 
thermoset screw and barrel assembly. The mold was heated with hot oil from 
a Mokon Model 105-057 heating unit. Cavity pressure was recorded with a 
Control Process Model 241 recorder. The mold was equipped to handle 
pressure transducers at the ejector pins located at the gate end of the 
tensile bar and the gate end of the flex bar before we began our work. 
Since it was desirable to make cavity pressure measurements at the dead 
end of the flex bar, it was necessary to make some modifications in the 
mold base to accommodate a transducer at this pin position. 
Resins were dried in a desiccant hot air circulating oven at 300.degree. F. 
for at least 16 hours before testing. Moisture in amide-imide homopolymer 
copolymers has a very significant effect on their flow properties; 
therefore, special care was taken to be sure the samples were properly 
dried. This drying procedure was used before making flow rate and cavity 
pressure measurements. 
The flow rate procedure was patterned after the standard method described 
in ASTM D1238. A 335.degree. C. (635.degree. F.) barrel temperature with a 
30 minute preheat time was used. This is about the largest set of weights 
that can be used safely with the standard extrusion plastometer apparatus. 
A standard 0.0825 in. diameter, and a 0.315 in. long orifice was used. 
Special care was taken to be sure that each flow rate measurement was 
started when an equivalent volume of resin was in the barrel. Previous 
rheology work indicated that there is a very large "barrel height" effect 
on amide-imide homopolymers and copolymers. Each flow rate measurement was 
initiated while the top of the piston collar was between the two scribe 
marks on the piston. This precaution is also required by ASTM in method 
D1238. 
Laminates of amide-imide homopolymer and copolymer solution impregnated 
graphite fiber woven fabric have been produced at lower molding pressures 
when up to 10 percent by weight of amorphous polyamide is added to the 
impregnation solution. 
The blended solution was used to coat 26".times.42" pieces of graphite 
fiber woven fabric. The fabric was woven from Thornel 300 fiber into an 8 
harness satin weave weighing 370 g/m.sup.2. Both solution and fabric were 
preweighed to yield 35 percent dry resin content coated fabric after 
solvent extraction. The fabric was taped to polyethylene film and the 
solution was worked into the fabric with a propylene squeegee. The coated 
fabric was dried at ambient until tack free, then oven dried at 
300.degree. F. for 16 hrs. After drying, the fabric was cut to size and 
loaded in a mold preheated to 650.degree. F. The mold was partially closed 
on 0.250" shims for 5 minutes to allow additional devolitization while the 
material and the mold were heated to the 650.degree. F. mold temperature. 
Full pressure was applied for 5 minutes followed by a double bump (partial 
opening of mold) to allow venting of entrapped volatile matter. The 
laminates were then cooled to 450.degree. F. for demolding. 
It has been found that the amide-imide homopolymers and copolymers are 
improved by the addition of amorphous polyamide coated or sized 
reinforcing material; particularly the mechanical properties of the 
polyimides are improved if these copolyimides contain from about 20 to 60 
percent by weight glass fibers, glass beads, industrial materials such as 
talc, or graphite or mixtures thereof. In the preferred range the 
polyimides contain 30 to 40 percent by weight of the glass fibers, glass 
beads, talc or graphite or mixtures thereof. Suitably reinforcing 
materials can be glass fibers, glass beads, glass spheres, and glass 
fabrics. The glass fibers are made of alkali-free boron-silicate glass or 
alkali-containing C-glass. The thickness of the fiber is suitably on the 
average between 0.003 mm and 0.03 mm. It is possible to use both long 
fibers with average lengths of from 1.5 to 15 mm and also short fibers of 
an average filament length from 0.05 to 5 mm. In principle, any standard 
commercial-grade fibers, especially glass fibers, may be used. Glass beads 
ranging from 0.005 mm to 0.8 mm in diameter may also be used as a 
reinforcing material. 
The reinforced polyamide-imide homopolymers and copolymers may be prepared 
in various ways. For example, so-called roving endless glass fiber strands 
are coated with the amorphous polyamides disclosed herein and then are 
further coated with the polyamic acid melt and subsequently chopped. The 
chopped fibers or the glass beads coated with amorphous polyamides may 
also be mixed with granulated polyamic acid and the resulting mixture 
melted in a conventional extruder, or alternatively the fibers coated with 
amorphous polyamide may be directly introduced into the polyamic acid melt 
through a suitable inlet in the extruder. Injection molding of the 
unfilled or glass-filled copolyamide-imides accomplished by injecting the 
copolyamide-imides into a mold maintained at a temperature of about 
350.degree. F. to 450.degree. F. In this process a 15 to 30 second cycle 
is used with a barrel temperature of about 580.degree. F. to 640.degree. 
F. The injection molding conditions are given in Table 2. 
TABLE 2 
______________________________________ 
Set 
Points 
______________________________________ 
Cylinder Temperatures (.degree.F.) 
Nozzle 630 
Front Zone 630 
Rear Zone 620 
Timer (seconds) 
Clamp Closed (cure) 18 
Injection Hold 6 
Booster (Inj. Hi) 2 
Cycle Delay (open) 1 
High-Low 2 
Injection Pressure (psi) 
High 20,000 
Low 10,000 
Machine Settings 
Clamp Pressure (tons) 
Max. 
Injection Rate Max. 
Screw RPM 50 
Feed Setting As required 
Cushion 1/4" 
Back Pressure (psi) 220 
Mold Temperature (.degree.F.) 
Stationary 450 
Movable 450 
Hopper Drier 220 
______________________________________ 
The mechanical properties of the unfilled amide-imide copolymers containing 
amorphous polyamides (melt compounded) and also the filled amide-imide 
copolymers are given in Table 3 and it shows that these homopolymers and 
copolymers have excellent mechanical and thermal properties despite the 
fact that they contain 4 to 5 weight percent of amorphous polyamides. 
TABLE 3 
__________________________________________________________________________ 
Amide-Imide 
Amide-Imide 
Amide-Imide (Example II 
(Example I 
(Example I Preparation) 
Preparation) 
Preparation) 
__________________________________________________________________________ 
Mineral Fiber 
0 0 0 0 0 0 40 40 
Content, % 
Glass Fiber 
0 0 30 30 40 40 0 0 
Content, % 
% Trogamid-T* 
0 5 0 4.3 0 5 0 5 
Annealed Properties 
Tensile Strength 
28.9 
25.4 
31.0 
29.9 
30.6 
26.2 
21.2 
18.0 
.times. 10.sup.3 psi 
Tensile Elongation % 
14.2 
17.1 
7.45 
6.84 
5.7 4.8 3.7 3.5 
Flexural Strength 
33.6 
32.3 
45.3 
44.8 
50.9 
44.4 
28.3 
25.1 
.times. 10.sup.3 psi 
Flexural Modulus 
.792 
.635 
1.72 
1.61 
1.95 
1.83 
1.51 
1.43 
.times. 10.sup.6 psi 
HDT at 264 psi .degree.F. 
534 526 539 526 560 544 545 510 
Izod Impact 
2.5 2.6 1.5 1.6 0.95 
0.86 
0.75 
0.73 
ft.-lbs./in of 
notch 
Tg .degree.F. molded 
495 478 -- -- -- -- -- -- 
annealed 538 527 540 540 545 536 
545 518 
Thermal Aging 
Tensile Strength 
.times. 10.sup.3 psi 
250 hrs. at 500.degree. F. 
29.2 
25.0 
-- -- 32.7 
28.9 
1000 hrs. at 500.degree. F. 
28.0 
23.1 
-- -- 32.5 
26.4 
Flexural Modulus 
.times. 10.sup.6 psi 
250 hrs. at 500.degree. F. 
.761 
.635 
-- -- 2.05 
1.88 
1000 hrs. at 500.degree. F. 
.766 
.659 
-- -- 1.94 
1.88 
Tg .degree.F. 
250 hrs. at 500.degree. F. 
538 527 -- -- 554 541 
1000 hrs. at 500.degree. F. 
554 543 -- -- 554 543 
400.degree. F. Properties 
Flexural Strength 
-- -- 29.1 
27.9 
36.1 
31.1 
.times. 10.sup.3 psi 
% R.T. Retention 
-- -- 64 62 71 70 
Flexural Modulus 
-- -- 1.38 
1.34 
1.72 
1.59 
.times. 10.sup.6 psi 
% R.T. Retention 
-- -- 81 83 88 87 
Flow; Cavity Pressure 
.times. 10.sup.3 psi 
at 18 seconds 
12.7 
15.4 
5.0 11.7 
13.5 
19.1 
0 11.4 
at 90 seconds 
NR NR 0 9.5 0 20.3 
NR NR 
__________________________________________________________________________ 
*Polymer Weight: Melt compounded with AmideImide prior to injection 
molding. 
NR: Not Run. 
Glass Fibers: 1/8" PPG 3540. 
Mineral Fibers: Wollastokup 1100 0.5. 
All of the materials studied were molded on the 10 oz. Stokes injection 
molder under Table I molding conditions unless specified otherwise. A 10 
oz. Stokes injection molder is fitted with a 1:1 compression thermoset 
screw which can hold approximately 365 grams of amide-imide polymer and 
copolymer (approximately 0.8 lbs.). Since each test tree weighs 
approximately 23 grams (neat parts) only 1/16th of the complete injection 
stroke (shot volume) is used during the molding evaluation. Under these 
conditions (18 second clamp), the total time the polymer is trapped in the 
barrel is approximately 7.2 minutes (total cycle is 27 seconds). This does 
not mean that the polymer is in the melt state for the complete 7.2 
minutes due to the temperature gradient (front to rear) in the barrel. For 
a complete material transition (purge) 16-20 shots must be taken before 
collecting data. 
Amide-imide polymer and copolymer flow, under molding conditions, is 
determined by its cavity pressure which is measured at a point farthest 
from the sprue. In this test, a pressure transducer is fitted behind a 
knockout point located behind the flex bar. The higher the cavity 
pressure, the better the flow thus making for easier mold filling. To 
determine our amide-imide copolymer reactivity a plot of cavity pressure 
vs. cycle time is drawn. A stable or non-reactive resin will exhibit good 
flow characteristics under adverse molding conditions resulting in a melt 
insensitive to a change in cycle time. A reactive polymer will be cycle 
time dependent in that its viscosity increases with cycle time. This is 
illustrated by a steep negative cavity pressure slope. Amide-imide polymer 
and copolymer samples were all dried for approximately 16 hours at 
300.degree. F. in a hot air circulating oven containing a suitable 
desiccant. The amorphous polyamides were dried overnight in a vacuum oven 
at 230.degree. F. Samples were dry blended together and stored under 
vacuum in sealed containers. (A-I Product define in Example 2.) 
Amide-imide polymer and copolymer samples were cured in a Blue M hot air 
programmable oven under a 7 day cycle with 1 day at 320.degree. F., 
400.degree. F., 450.degree. F., 475.degree. F. and 3 days at 495.degree. 
F. Several tensile bars were cured under a 7 day cycle with 3 days at 
500.degree. F. These parts were measured for shrinkage. The 3 percent 
(total weight) Trogamid-T, Amidel and Copolyamide, amide-imide blends were 
cured at 500.degree. F. and these materials were ASTM tested.

The following examples illustrate the preferred embodiment of the 
invention. It will be understood that the examples are for illustrative 
purposes only and do not purport to be wholly definitive with respect to 
conditions or scope of the invention. 
EXAMPLE I 
A 200 ml. round bottom 4-neck flask, equipped with a nitrogen inlet tube, 
stirrer, thermometer, and solids addition funnel, was charged with 99.9 
parts by weight of (pbw) p,p'-oxybis(aniline) (OBA), 23.1 pbw 
metaphenylenediamine (MPDA) and 604 pbw N-methylpyrrolidone (NMP). When 
solution at room temperature (72.degree. F.) was complete, 142.5 pbw 
4-trimellitoyl anhydride chloride (4-TMAC), having a percent purity of 
99.5 percent .+-.0.5 percent as determined from chloride content and 6.8 
pbw of trimellitic acid anhydride (TMA) was added over 2.5 hours while 
maintaining a solution temperature of between about 77.degree.-95.degree. 
F. When addition was complete the solution was stirred for 3 hours during 
which time the solution viscosity increased to a Gardner-Holdt value of 
Z5+or about 110 poises. 
Solid polymer was obtained by first pouring the viscous solution into twice 
its volume of distilled water in a Waring blender and then filtering. The 
filtrate is washed with 5 increments of 3000 pbw each of distilled water 
to remove hydrogen chloride that had been generated during reaction. 
The solid was dried under a vacuum of 20 inches of mercury for 24 hours at 
122.degree. F. The above material was heated for 2 hours in an oven set at 
450.degree. F. to give the final product. 
EXAMPLE II 
A 10 gal glass-lined Pfaudler kettle equipped with a water-cooled jacket 
and nitrogen inlet was charged with 9.87 lbs. of m-phenylenediamine, 0.35 
lbs. of trimellitic anhydride and 59.2 lbs. of N-methylpyrrolidone. After 
solution had occurred under a nitrogen purge, an intimate blend of 9.52 
lbs. of 4-trimellitoyl anhydride chloride and 9.17 lbs. of isophthaloyl 
dichloride was added over 2.5 hrs. keeping the temperature below 
35.degree. C. The resulting viscous solution was brought to 50.degree. C. 
When the Gardner viscosity had reached a Z3 viscosity the solution was 
precipitated by passage through a Fitzpatrick comminuting mill. The 
polymer product was washed five times with deionized water followed by 
air-drying on a filter for 3 days. The product was then brought to a 
solids content of 98.3 percent by heating in a forced air oven for 2 hrs. 
at 470.degree. F. 
EXAMPLE III 
Metaphenylenediamine (540 g) and acetic acid (900 ml) were placed in a five 
liter three-necked round bottom flask equipped with mechanical stirrer, 
pressure equalizing addition funnel and nitrogen sparge tube, and 
distillation head and condenser. The nitrogen sparge was set at 300 cc/min 
and 765 g of acetic anhydride was added over 5 min. This was followed by 
the addition of 415 g of isophthalic acid and 480 g of trimellitic 
anhydride. The temperature of the bottom half of the spherical heating 
mantle surrounding the flask was set at 700.degree. F. and the top half of 
the mantle was heated with a Variac set at 50. After 105 min., 1730 ml of 
distillate was collected and the polymer had become very viscous. The heat 
was turned off and the polymer was cooled under nitrogen. 
EXAMPLE IV 
A 690 gram portion of dimethylacetamide was stirred and cooled to 5.degree. 
C. with dry nitrogen purging to keep the system dry. An intimate mixture 
composed of 252.2 grams of 4-TMAC, 119.0 grams of 
p',p-methylene-bis(aniline), and 120.0 grams of p,p'-oxybis(aniline) was 
then added to the solvent over a period of 30 minutes. The temperature of 
the reaction was allowed to rise to 50.degree. C. At that temperature it 
was controlled by means of an ice bath. An additional 100 grams of DMAC 
were then added to wash in all solids, and the reaction continued for 
another 31/2 hours at 50.degree. C. The reaction solution was then poured 
into a large excess of rapidly-agitated water, whereupon precipitation of 
the copolymer took place. The solids were then washed several times with 
distilled water and soaked overnight. Finally, the solids were dried at 
120.degree. F. A 443 gram yield of the copolymer was obtained. 
EXAMPLE V 
A solution consisting of 533.3 grams of NMP, 300 grams of DMAC, and 58.0 
grams of propylene oxide was stirred and cooled to 8.degree. C. A mixture 
of 168.5 grams of 4-TMAC, 80.1 grams of OBA, and 79.3 grams of MBA was 
then added to the solvent over a period of 50 minutes. During this time 
the reaction was allowed to warm to 36.degree. C. An additional 66.7 grams 
of NMP were added to wash in all solids, then the reaction mixture was 
heated to 50.degree. C. and held at that temperature for 31/2 hours. The 
solution was then filtered. 
EXAMPLE VI 
The general procedure for preparing a copolymer containing three diamines 
is illustrated by the reaction of OBA, MPDA and MBA and 4-TMAC in DMAC. 
Thus, a 242.0 gram portion of OBA (1.21 moles), a 130.7 gram portion of 
MPDA (1.21 moles) and a 239.6 gram portion of MBA (1.21 moles) were 
dissolved in 3,900 grams DMAC contained in a 6 liter flask equipped with a 
nitrogen purge, stirrer, addition funnel and thermometer. A 765 gram 
portion of 4-TMAC (3.63 moles) in flake or lump form was then added to the 
solution in portions over 90 minutes. The reaction exotherm was allowed to 
raise the temperature to about 35.degree. C. The reaction temperature was 
maintained at 33.degree.-38.degree. C. for the remainder of the 4-TMAC 
addition using cooling water when necessary. After the TMAC addition was 
completed, any residual TMAC clinging to the addition funnel was 
completely washed into the reaction solution with 70 grams DMAC. A heating 
mantle was applied to the reaction flask and the temperature quickly 
raised (about 20 min.) to 50.degree. C. The reaction solution was stirred 
at 50.degree. C. for 90 minutes and then the solution precipitated by 
admixing with water. Prior to precipitation the solution viscosity was 
about 7.5 stokes (25.degree. C., 20 percent solids). The polymer was 
precipitated in distilled water in a model D, W. J. Fitzpatrick Company, 
comminuting machine (Fitz mill). After precipitation the polymer was 
washed with distilled water to aqueous pH 4 to 5 (3 to 4 hours washing 
time), then filtered onto large Buchner funnels. The polymer was dried 
overnight by drawing air through the funnels, then finally dried in an 
aeromat drier at 30.degree.-35.degree. C. for 12-15 hours. 
EXAMPLE VII 
A 78 gram amount of the copolymer in powdered form made according to the 
procedure set forth in Example I was heated at 550.degree. F. for about 1 
hour. It was then cooled and charged cold into a mold preheated in the 
press to about 600.degree. F. to about 650.degree. F. A maximum pressure 
of 4,200 psi was applied over a 25 minute period and thereafter the mold 
and contents cooled to 500.degree. F. under a pressure of 2,100 psi and 
the molded item immediately ejected. A disk measuring 51/2 inches in 
diameter and 1/8 inch thick had been formed. 
EXAMPLE VIII 
Neat amide-imide amorphous polyamide blends can be prepared by physically 
blending the constituents together, either pellet to pellet, powder to 
powder, powder to pellet, or pellet to powder with or without a 
compounding step prior to injection molding. It is preferred that the 
constituents are melt compounded; however, favorable results can be 
achieved without melt compounding. 
The filled amide-imide amorphous polyamide blends can be prepared as 
described above or the amorphous polyamide can be dissolved in a solvent 
and spray coated or dip coated on the filler and/or reinforcement 
(graphite fibers, glass fibers, and mineral fillers). Trogamid-T is 
readily soluble in N-methyl-2-pyrrolidone (NMP). Thus a solution of about 
1 to 5 percent Trogamid-T by weight of total solution can be coated on the 
reinforcement and/or filler. Table 4 compares 40 percent glass-filled 
amide-imides (Example II) which have been dry blended and melt compounded 
with an amorphous polyamide. 
TABLE 4 
______________________________________ 
Glass Content, % 40 40 
Blend Procedure dry melt 
% Amorphous Polyamide 
5 5 
(Polymer Wgt.) 
Physical Properties* 
Tensile Strength .times. 10.sup.3 (psi) 
27.0 26.2 
Tensile Elongation % 5.0 4.8 
Flexural Strength 43.1 44.4 
.times. 10.sup.3 (psi) 
Flexural Modulus 1.86 1.83 
.times. 10.sup.6 (psi) 
HDT (.degree.F.) 538 544 
Izod Impact (ft.-lb./ 
1.0 0.86 
in. of notch) 
______________________________________ 
*Annealed 
EXAMPLE IX 
An amide-imide resin (Example II preparation) was dry blended with 40 
percent glass fibers from Pittsburg Plate Glass Corporation, identified as 
PPG 3540, and 1 percent PTFE and then melt compounded. This sample was dry 
blended with 1 to 5 percent by total weight of an amorphous polyamide 
(Trogamid-T) or 1.67 to 8.33 percent by weight of the amide-imide polymer 
weight and injection molded. Parts were annealed on a 7-day cycle, 
320.degree. F., 400.degree. F., 450.degree. F., 475.degree. F., and 3 days 
at 495.degree. F. Physical properties, molded part physical properties, 
and molded part shrinkage are given in Table 5 below. 
TABLE 5 
______________________________________ 
Glass Content, % 40 40 
Amorphous Polyamide 0 1 
Content, % 
Part I.V. dl/g 
0.30 0.30 
Thermal Properties 
ASTM Method 
Glass Transition 
Temperature (Tg), .degree.F. 
As Molded 505 493 
Annealed* 532 525 
Annealed Tg Increase 27 32 
Physical Properties* 
HDT, .degree.F. 
D-48 549 540 
Tensile Strength, 
D-1708 20,400 23,600 
psi 
Tensile Elongation, 
D-1708 5.6 6.8 
Flexural Modulus, 
D-790 1,970,000 1,930,000 
psi 
Flexural Strength, 
D-790 45,000 46,600 
psi 
Izod, ft-lbs/in 
D-256 0.89 0.86 
of notch 
Molding Results 
Total Shrinkage 0.7 0.7 
(mils/in) 
Cavity Pressure, 10,300 12,600 
psi 
______________________________________ 
EXAMPLE X 
An amide-imide (Example II preparation) resin was dry blended with 40 
percent PPG 3540 glass fibers and 1 percent PTFE and melt compounded. The 
sample was dry blended with 3 percent by total weight of Trogamid-T, 
Amidel, or Copolyamide. Parts were annealed on a 7-day cycle with 3 days 
at 500.degree. F. Physical properties, flow, and shrinkage dates are shown 
below in Table 6. 
TABLE 6 
______________________________________ 
Amide-Imide (Example II Preparation) 
Amorphous 
Polyamide Copoly- 
Content Control Trogamid-T Amidel amide 
______________________________________ 
Total weight 
0 3 3 3 
basis, % 
A-I Polymer 
0 5 5 5 
weight basis, % 
Cavity Pressure, 
10,300 16,900 21,100 18,800 
psi 
Total Shrinkage, 
0.7 1.7 1.7 1.7 
mils/inch 
Physical 
Properties* 
Tensile Strength, 
30,500 27,000 25,700 24,100 
psi 
Tensile Elong- 
5.5 5.0 4.3 4.2 
ation, % 
Flexural Strength, 
50,900 43,100 44,100 43,200 
psi 
Flexural Modu- 
1,960,000 
1,860,000 1,750,000 
1,850,000 
lus, psi 
HDT, .degree.F. 
555 538 519 518 
Izod Impact, 
0.9 1.0 0.9 0.9 
Ft-lbs/in notch 
Annealed Tg, 
532 520 523 523 
.degree.F. 
______________________________________ 
*Cure Cycle: 1 day at 320.degree. F., 400.degree. F., 450.degree. F., 
475.degree. F.; 3 days at 500.degree. F. 
EXAMPLE XI 
An amide-imide resin prepared as in Example I which was melt compounded 
with 0.5 percent PTFE or 30 percent PPG 3540 glass fibers and 1 percent 
PTFE and pelletized. These materials were dry blended with an amorphous 
polyamide (Trogamid-T). The parts injection molded from these materials 
were annealed under a 7-day cycle with 3 days at 500.degree. F. Physical 
properties, flow, and shrinkage data are given in Table 7 below. FIG. 4 
illustrates the difference in flow and melt stability the Trogmaid-T added 
to the 30 percent glass filled amide-imide resin. FIG. 5 illustrates the 
difference in flow and melt stability with Trogamid-T added to an 
amide-imide resin without glass fiber filler. 
TABLE 7 
__________________________________________________________________________ 
Amide-Imide (Example I) 
__________________________________________________________________________ 
Glass Content, % 30 30 0 0 
Amorphous Polyamide 
Content 
Total Weight 0 5.00 0 5 
Basis, % 
Amide-Imide Weight 0 7.14 0 5 
Basis, % 
Cavity Pressure, 8,800 15,500 
14,500 
16,400 
psi 
Total Shrinkage, 0.7 4.4 7.0 8.7 
(mils/in) 
Physical Properties* 
ASTM Method 
Tensile Strength, 
D-1708 31,200 
25,300 
28,400 
27,200 
psi 
Tensile Elongation, 
D-1708 7.6 7.5 15.4 16.6 
Flexural Modulus, 
D-790 1,790,000 
1,490,000 
710,000 
680,000 
psi 
Flexural Strength, 
D-790 47,100 
42,600 
33,600 
32,300 
psi 
Izod, ft-lbs/in 
D-256 1.61 1.77 2.45 2.71 
of notch 
Thermal Properties 
Tg, as molded, .degree.F. 
502 464 495 481 
Tg, annealed, .degree.F. 
540 507 531 523 
HDT, .degree.F. 
D-48 513 515 535 535 
__________________________________________________________________________ 
*7-Day Cure Cycle: 1 day at 320.degree. F., 400.degree. F., 450.degree. 
F., 475.degree. F.; 3 days at 500.degree. F. 
EXAMPLE XII 
An amide-imide Example III preparation) resin which contained 40 percent 
milled glass and 1 percent PTFE was melt compounded and dry blended with 5 
percent by weight of Trogamid-T. Parts were molded with and without 
Trogamid-T. The control (no Trogamid-T) was so viscous that it stalled the 
injection molder screw during reciprocation, thus, the run was aborted to 
prevent the screw from seizing. When 5 percent (total weight) Trogamid-T 
was dry blended into this material, a cavity pressure of 12,000 psi was 
obtained. The melt reactivity during plastication was inhibited as 
illustrated in FIG. 5. 
EXAMPLE XIII 
A neat amide-imide (Example I preparation) was melt compounded with 5 
percent and 20 percent by weight of Trogamid-T. Parts were molded on the 
10 oz. Stokes injection molder at about 630.degree. F. The 5 percent 
Trogamid-T amide-imide material and the control were annealed at 
500.degree. F. for 3 days prior to testing. The 20 percent Trogamid-T 
amide-imide blend parts distorted during the 500.degree. F. annealing 
processing, thus, properties were not measured. At the 20 percent 
Trogamid-T loading the as molded amide-imide part Tg was 410.degree. F. 
(210.degree. C.) and after annealing it rose 40.degree. F. to 450.degree. 
F. (232.degree. C.). The 20 percent Trogamid-T amide-imide blend maximum 
Tg was 450.degree. F., some 50.degree. F. below the maximum annealing 
temperature, thus examplifying the distortion during annealing due to 
stress relaxation of the part. The amide-imide controls as molded and 
annealed Tg's were 495.degree. F. and 531.degree. F. while the 5 percent 
Trogamid-T amide-imide blend had as molded and annealed Tg's of 
489.degree. F. and 523.degree. F. 
EXAMPLE XIV 
N-methyl-2-pyrrolidone (NMP) is a solvent for both polymers of 
interest-polyamide-imide and Trogamid-T. A 27.5 percent solids solution of 
Trogamid-T in NMP was prepared as follows. The NMP 725 grams) was heated 
to 180.degree. F., and stirred with a high shear blade mixer with 
sufficient speed to keep the Trogamid-T pellets from agglomerating when 
added to the solvent. The Trogamid-T pellets were added to the hot solvent 
over a 20-minute period. After .apprxeq.11/2 hours mixing, all pellets 
were dissolved. Mixing was continued for 2 hours after all pellets 
appeared to be dissolved. The solution was allowed to cool and sit 16 
hours before using. 
The Trogamid-T solution described above was blended with a 
polyamide-imide/NMP solution (27.5 percent solids) at a 95:5 weight ratio. 
The polyamide-imide solution was first heated to 150.degree. F. The 
Trogamid solution was thus added, and the blend was stirred with a high 
shear mixer for four hours. The blended solution was allowed to cool and 
sit 16 hours before using. 
The blended solutions of polyamide-imide/Trogamid-T were used to coat 
graphite fiber woven fabric. The laminates formed from these blends and a 
control are listed in the Table below. 
TABLE 8 
______________________________________ 
Molded Short Beam 
Sample Pressure, psi 
Shear (SBS), ksi 
______________________________________ 
Control 3000-4000 10-11 
82-01-13-01 2000 11.45 
82-01-13-02 1500 11.69 
82-01-14-01 1000 11.50 
______________________________________ 
Laminates using 100 percent polyamide-imide require molding pressures of 
3000 to 4000 psi to obtain void free parts with good surface appearance. 
Laminates utilizing the polyamide-imide/Trogamid-T blend were molded at 
pressures of 2000, 1500, and 1000 psi: mold pressure respectively. A good 
quality laminate will have short beam shear (SBS) strength of 10-11 ksi as 
molded. The blend laminates have SBS strengths above 11 ksi.