Polyetherimide having long chain aliphatic end groups and method for making

Polyetherimides having long chain aliphatic end groups have been found to exhibit significantly lower melt viscosities and higher notched izod impact values compared to comparable polyetherimides end capped with organic radicals derived from aromatic organic amines or aromatic organic anhydrides.

CROSS REFERENCE TO RELATED APPLICATIONS 
Reference is made to my copending application Ser. No. 37,438, filed May 9, 
1979, now abandoned, for Injection Moldable Polyetherimide Oligomers and 
Ser. No. 37,437, now abandoned, filed May 9, 1979, for Particulated 
Polyetherimide and Method for Making of Eugene G. Banucci et al, where 
both applications are assigned to the same assignee as the present 
invention. 
BACKGROUND OF THE INVENTION 
The present invention relates to a method for improving the melt viscosity 
of polyetherimides by incorporating long chain alkylamine chain-stoppers 
during the melt polymerization of aromatic bis(ether anhydride) and 
aromatic diamine used in the production of such polyetherimides, or during 
the formation of polyetherimide prepolymers. 
Prior to the present invention, as shown by copending application Ser. No. 
37,438, filed May 9, 1979 and assigned to the same assignee as the present 
invention, injection moldable polyetherimide oligomers were made by 
effection reaction between substantially equal molar amounts of organic 
dianhydride of the formula, 
##STR1## 
and organic diamine of the formula, 
EQU H.sub.2 N--R--NH.sub.2, (2) 
under interfacial polymerization conditions, where Z is a member selected 
from 
##STR2## 
and divalent organic radicals of the general formula, 
##STR3## 
where X is a member selected from the class consisting of divalent 
radicals of the formulas, 
##STR4## 
where y is an integer from 1 to 5, and R is a divalent organic radical 
selected from the class consisting of aromatic hydrocarbon radicals having 
from 6 to about 20 carbon atoms and halogenated derivatives thereof, 
alkylene radicals having from 2 to about 20 carbon atoms, cycloalkylene 
radicals having from 3 to about 20 carbon atoms, from C.sub.2 to about 
C.sub.8 alkylene terminated polydiorganosiloxane and divalent radicals of 
the formula, 
##STR5## 
where Q is a member selected from --O--, --S--, --SO.sub.2 --, --CO--, and 
--C.sub.x H.sub.2x --, x is an integer from 1 to 5 and a is 0 or 1. 
Although the above described polyetherimides consisting essentially of 
chemically combined units of the formula, 
##STR6## 
where R and Z are as previously defined, can be used as high performance 
injection moldable thermoplastics, the zero shear viscosity of the 
resulting thermoplastic can be 15.8.times.10.sup.5 poise at 300.degree. C. 
Even though the aforementioned thermoplastic materials have valuable 
injection moldable characteristics, those skilled in the art know that the 
aforementioned zero shear viscosity is undesirably high for particular 
applications. In addition, the resulting molded parts are often found to 
adhere to the surfaces of the mold resulting in complications in 
fabrication. In addition, the surface characteristics of the 
polyetherimide often did not satisfy the requirements of the fabricator in 
instances where a glossy appearance was required. The present invention is 
based on the discovery that polyetherimides, consisting essentially of 
units of formula 3 having a significant reduction in melt viscosity during 
melt polymerization and improved mold release and surface characteristics 
can be made by utilizing an effective amount of a long chain aliphatic 
hydrocarbon alkyl amine of the formula, 
EQU R.sup.1 --NH.sub.2, (4) 
where R.sup.1 is a aliphatic radical having from 12-20 carbon atoms, during 
the melt polymerization of substantially equal molar amounts of the 
organic dianhydride of formula (1) and organic diamine of formula (2). 
STATEMENT OF THE INVENTION 
There is provided by the present invention polyetherimides consisting 
essentially of chemically combined units of the formula, 
##STR7## 
and terminal radicals of the formula, 
EQU --R.sup.1, 
where Z, R and R.sup.1 are as previously defined. 
There is further provided by the present invention a method for making 
polyetherimide consisting essentially of chemically combined units of 
formula (3) which effects a substantial reduction in the melt viscosity of 
the resulting polyetherimide and improves its mold release properties 
which comprises melt polymerizing substantially equal molar amounts of 
organic dianhydride of formula (1) and organic diamine of formula (2) or 
prepolymer obtained therefrom in the presence of an effective amount of 
aliphatic organic amine of formula (4). 
Among the aromatic bis(ether anhydride)s of formula (1) there are included 
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; 
4,4'-bis(3,4-dicarboxyphenoxy)benzophenone dianhydride; 
4,4'-bis(3,4-dicarboxyphenoxy)diphenyl sulfone dianhydride; 
2,2-bis[4-(2,3-dicarboxyphenoxy)phenyl]propane dianhydride; 
4,4'-bis(2,3-dicarboxyphenoxy)diphenyl ether dianhydride; 
4,4'-bis(2,3-dicarboxyphenoxy)diphenyl sulfide dianhydride; 
4,4'-bis(2,3-dicarboxyphenoxy)benzophenone dianhydride; 
4,4'-bis(2,3-dicarboxyphenoxy)diphenyl sulfone dianhydride; 
4-(2,3-dicarboxyphenoxy)-4'-(3,4-dicarboxyphenoxy)diphenyl-2,2-propane 
dianhydride, 
and mixtures thereof. 
Aromatic bis(ether anhydride)s especially preferred herein are 
2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, 
2,2-bis[4-(2,3-dicarboxyphenoxy)phenyl]propane dianhydride; 
4-(2,3-dicarboxyphenoxy)-4'-(3,4-dicarboxyphenoxy)diphenyl-2,2-propane 
dianhydride; and mixtures thereof. 
Some of the aromatic bis(ether anhydride)s of formula (1) are shown in U.S. 
Pat. No. 3,972,902 (Darrell Heath and Joseph Wirth). As described therein, 
the bis(ether anhydride)s can be prepared from the hydrolysis, followed by 
dehydration of the reaction product of a nitro-substituted phenyl 
dinitrile with a metal salt of a dihydric phenol compound in the presence 
of a dipolar aprotic solvent. 
Additional aromatic bis(ether anhydride)s also included by formula (1) are 
shown by Koton, M. M. Florinski, F. S. Bessonov, M. I. Rudakov, A. P. 
(Institute of Heteroorganic Compounds, Academy of Sciences, (U.S.S.R.) 
257,010, November 11, 1969, Appl. May 3, 1967, and by M. M. Koton, F. S. 
Florinski, Zh. Org. Khin. 4 (5), 774 (1968). 
There are included within formula (3), organic diamines such as 
o-phenylenediamine; 
m-phenylenediamine; 
p-phenylenediamine; 
4,4'-diaminodiphenylpropane; 
4,4'-diaminodiphenylmethane (commonly named 4,4'methylenedianiline); 
4,4'-diaminodiphenylsulfide (commonly named 4,4'thiodianiline); 
4,4'-diaminodiphenyl ether (commonly named 4,4'oxydianiline); 
1,5-diaminonaphthalene; 
3,3'-dimethylbenzidine; 
3,3'-dimethoxybenzidine; 
2,4-bis(.beta.-amino-t-butyl)toluene; 
bis(p-.beta.-amino-t-butyl)ether; 
bis(p-.beta.-methyl-o-aminopentyl)benzene; 
1,3-diamino-4-isopropylbenzene; 
1,2-bis(3-aminopropoxy)ethane; 
benzidine; 
m-xylylenediamine; 
p-xylylenediamine; 
2,4-diaminotoluene; 
2,6-diaminotoluene; 
bis(4-aminocyclohexyl)methane; 
3-methylheptamethylenediamine; 
4,4-dimethylheptamethylenediamine; 
2,11-dodecanediamine; 
2,2-dimethylpropylenediamine; 
octamethylenediamine; 
3-methoxyhexamethylenediamine; 
2,5-dimethylhexamethylenediamine; 
2,5-dimethylheptamethylenediamine; 
3-methylheptamethylenediamine; 
5-methylnonamethylenediamine; 
1,4-cyclohexanediamine; 
1,12-octadecanediamine; 
bis(3-aminopropyl)sulfide; 
N-methyl-bis(3-aminopropyl)amine; 
hexamethylenediamine; 
heptamethylenediamine; 
nonamethylenediamine; 
decamethylenediamine; 
bis(3-aminopropyl)tetramethyldisiloxane; 
bis(4-aminobutyl)tetramethyldisiloxane; 
and mixtures of such diamines. 
Organic diamines preferred herein are 4,4'-methylenedianiline, 
4,4'-oxydianiline, metaphenylenediamine, paraphenylenediamine, and 
mixtures thereof. 
In the practice of the invention the long chain alkyl amine chain-stopper, 
hereinafter referred to as "chain stopper", for example dodecylamine, 
cetyl amine, octadecylamine, etc., can be incorporated into the resulting 
polyetherimide during melt polymerization or as part of the prepolymer 
prior to melt polymerization. In one procedure, for example, the organic 
dianhydride and organic diamine can be melt polymerized in the presence of 
the chain-stopper. In another procedure the chain-stopper can be 
incorporated into the prepolymer chain ends prior to melt polymerization. 
In a further procedure the chain-stopper can be added to the prepolymer 
prior to melt polymerization. 
Experience has shown that during melt polymerization of the organic 
dianhydride and organic diamine, or in the formation of the prepolymer, 
substantially equal molar amounts of organic dianhydride and organic 
diamine will provide for effective results. However, higher or lower 
amounts of the aforementioned ingredients can vary in particular 
situations. It has been found that significant improvement in both a 
reduction in melt viscosity at injection molding temperatures of about 
300.degree. C. and mold release properties can be achieved in the 
polyetherimide to provide 0.5 to 10 mole percent of the chain-stopper, 
based on the total moles of organic dianhydride, and organic diamine used 
in the melt polymerization mixture. 
Melt polymerization of the various ingredients, for example, the organic 
dianhydride of formula (1), organic diamine of formula (2) and 
chain-stopper of formula (4) can be achieved at temperatures in the range 
of from 200.degree. C. to 400.degree. C., while a preferred temperature 
range is about 250.degree. C. to 350.degree. C. 
In instances where the polyetherimide consisting essentially of formula (3) 
units is prepared from prepolymer, the prepolymer can be prepared by 
contacting the organic dianhydride of formula (1) and organic diamine of 
formula (2) under conditions of high agitation in the presence of water 
and organic solvent to produce an oligomer. As previously indicated, the 
chain-stopper can be introduced during the formation of the oligomer or it 
can be added with the oligomer during the melt polymerization step. The 
recovery of the oligomer from the mixture can be achieved by stripping the 
organic solvent followed by recovery of the prepolymer from the aqueous 
mixture. 
Suitable organic solvents which can be used during the interfacial 
polymerization making the prepolymer are chlorinated hydrocarbons, such as 
methylene chloride, chloroform, dichloroethylene, aromatic hydrocarbons, 
such as benzene, toluene, xylylene, ethylbenzene, cumine; ether solvents, 
such as diethylether, isobutylether, etc. 
In preparing the prepolymer, it is preferred to add the organic diamine as 
an aqueous solution to an organic solvent solution of the organic 
dianhydride, while it is being agitated, such as being stirred, shaken, 
etc. However, effective results can be achieved if both solutions are 
contacted simultaneously, for example, in a common mixing vessel along 
with means for agitation. 
Reaction between the organic dianhydride and the organic diamine can be 
effected under interfacial conditions at a temperature in the range of 
0.degree. C. to 100.degree. C., and preferably 15.degree. C. to 50.degree. 
C. Depending upon such factors as the temperature, degree of agitation, 
nature of reactants, etc., time for the formation of the polymeramide acid 
can vary from 5 to 10 minutes or less to 1 to 2 hours or more. 
Polyetherimide made in accordance with the practice of the present 
invention can be injection molded at substantially lower pressures and 
temperatures and the resulting thermoplastic exhibits extremely good mold 
release properties. In general, the molded samples have a smooth and 
glossy surface. In addition, the notched Izod impact strength of the 
resulting polyetherimide is substantially better as compared to 
polyetherimide free of such chain-stopping units while the other 
mechanical advangages of polyetherimide are substantially maintained. 
Although the unexpected results of the enhanced properties of the 
polyetherimide made in accordance with the present invention are not 
completely understood, one possible explanation is that the change in 
surface properties is affected based on the orientation of aliphatic end 
groups towards the surface. The change in surface characteristics is 
evidenced by the dramatic change in the contact angle of the polymer 
surface with water. The polyetherimide thermoplastics or prepolymer can be 
blended with various inert fillers such as various particulated fillers, 
for example, glass fibers, silica fillers, carbon whiskers, which can be 
utilized at up to 50% by weight of the resulting blend.

In order that those skilled in the art will be better able to practice the 
invention, the following examples are given by way of illustration and not 
by way of limitation. All parts are by weight. 
EXAMPLE 1 
A mixture of 182.04 parts of metaphenylene diamine, 903.25 parts of 
2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride and 28.064 
parts of n-octadecylamine was heated at 265.degree. C. under argon. The 
mixture was vigorously stirred for 1.75 hours at 265.degree. C. and 
thereafter extruded. There was obtained tough amber colored strands of 
polyetherimide based on method of preparation. The intrinsic viscosity of 
the resulting polymer in chloroform was 0.48 dl/g. A dynamic visco elastic 
measurement indicated that the zero shear viscosity of the polyetherimide 
was 2.9.times.10.sup.5 poise at 300.degree. C. Molded specimens of the 
polyetherimide had high quality glossy surfaces and excellent mold release 
properties. The improved mold release properties and glossy surface is in 
agreement with the low surface energy which can be shown by a high contact 
angle with water droplets. In order to further determine the unexpected 
properties of the polyetherimide made in accordance with the practice of 
the present invention, polyetherimide was made following the same 
procedure, except that phthalic anhydride was used as a chain stopping 
agent in place of the n-octadecyl amine. In preparing the phthalic 
anhydride melt polymerization mixture, there was utilized a mole ratio of 
97 moles of organic dianhydride, 100 moles of meta-phenylene diamine and 6 
moles of phthalic anhydride. As shown in Table I below, two polymers were 
prepared by melt polymerization with the octadecylamine as a chain-stopper 
utilizing a mole ratio of 98 moles of meta-phenylene diamine, 100 moles of 
organic dianhydride and 4 moles of the octadecylamine, while the second 
polymer contained a mole ratio of 98 moles of the meta-phenylenediamine, 
100 moles of the organic dianhydride and 6 moles of the octadecylamine. 
The weight percent concentration of C.sub.18 H.sub.37 end groups and the 
contact angle with water for the resulting polyetherimide are shown in 
Table 1. 
TABLE I 
______________________________________ 
Polymer 
End Groups (WT %) 
Contact Angle 
Chain-stopper (mole %) 
(C.sub.18 H.sub.37) 
with H.sub.2 O 
______________________________________ 
Phthalic anhydride (6) 
-- 27.degree. 
Octadecylamine (4) 
1.69 41.degree. 
Octadecylamine (6) 
2.51 82.degree. 
______________________________________ 
The above results show that an increase in the concentration of --C.sub.18 
H.sub.37 end groups improves the surface characteristics of the resulting 
polyetherimide as shown by a high contact angle with water. 
The following table shows a comparison between polyetherimide made by the 
above procedure utilizing mixtures having phthalic anhydride at a mole 
ratio of about 6 moles to 100 moles of the metaphenylenediamine and 97 
moles of organic dianhydride with a melt polymerization product containing 
a mole ratio of 6 moles of octadecylamine with 100 moles of the organic 
dianhydride and 97 moles of metaphenylenediamine: 
TABLE II 
______________________________________ 
Polymer End Groups 
Mechanical Properties 
Phthalic Anhydride 
Octadecylamine 
______________________________________ 
Tensile Strength (PSI) 
at yield 15,100 15,500 
at rupture 13,000 12,400 
Elongation (%) 
at yield 7.8 7.4 
at rupture 92 80 
Flexural strength (PSI) 
at yield 21,000 23,000 
Flexural Modulus (PSI) 
480,000 480,000 
Notched Izod Impact 
1.0 1.4 
(ft.lb/m) 
______________________________________ 
The above results show that polyetherimide made with the above 
chain-stoppers are substantially the same, except that the octadecylamine 
shows a significant improvement in notched Izod Impact. 
EXAMPLE 2 
There was added 2.78 parts of octadecylamine over a period of about 10 
minutes to a mixture while it was stirring under nitrogen at room 
temperature consisting of 89.65 parts of 
2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride and 468 parts 
of methylene chloride. There was then added to the resulting mixture over 
a period of 15 minutes, an aqueous solution which was formed under 
nitrogen with 500 parts of deaerated water and 18.069 parts of 
metaphenylenediamine. There was obtained a polyamideacid which 
precipitated to form a white slurry. The slurry was further stirred at 
room temperature for an additional 4.5 hours and then heated to distill 
the methylene chloride. The methylene chloride was completely removed in 1 
hour and the temperature rose to 55.degree. C. The resulting aqueous 
suspension of the polyamide acid was cooled to room temperature and 
filtered. The precipitate was washed with about 200 parts of water and 
dried. There was obtained a 95.6% yield or 105.6 parts of polyamideacid. 
The above polyamideacid powder was placed in a vertical helicone mixer and 
heated with stirring at 270.degree. C. for 2 hours under argon. The 
resulting polymer was found to be glossy and exhibited the substantially 
the same characteristics with respect to reduced melt viscosity and 
improved notched Izod Impact as shown with the polyetherimide of Example 
1. 
EXAMPLE 3 
There was added 1.112 parts of dodecylamine over a period of five minutes 
to a stirred mixture of 51.046 parts of 
4,4'-bis(3,4-dicarboxyphenoxy)diphenyl sulfide dianhydride, 250 parts of 
water and 300 parts of chloroform. There was then added 19.423 parts of 
finely pulverized 4,4'-oxydianiline over a period of 15 minutes. The 
resulting slurry of a prepolymer was stirred at room temperature for an 
additional 15 minutes and heated to reflux for 45 minutes. The chloroform 
was then allowed to distill off over a period of 40 minutes and cooled to 
room temperature. The prepolymer was filtered and dried. There was 
obtained 71.2 parts of product which, based on its method of preparation 
and its infrared spectrum was a polyetheramide acid. 
Ther was placed 70 parts of the above oligomer in a Vertical Helicon Mixer 
and heated with stirring under an argon atmosphere at 280.degree. C. for 2 
hours. There was obtained an amber colored polyimide which had an 
intrinsic viscosity of 0.70 in m-cresol and glass transition temperature 
of 209.degree. C. 
Although the above examples are directed to only a few of the very many 
variables included within the method of the present invention, it should 
be understood that the present invention is directed to the use of a much 
broader variety of organic dianhydride of formula (1), organic diamine of 
formula (2) and chain stopper of formula (3).