Polyetherimide resins which crystallize from the melt contain crystallizing repeating units based on biphenoldianhydride or hydroquinone dianhydride and a linear aromatic diamine. The melt crystalline polyetherimides exhibit improved solvent resistance. The melt crystalline polymers retain the advantageous properties associated with their known amorphous polyetherimide counterparts.

BACKGROUND OF THE INVENTION 
The present invention relates to improvements to polyetherimide resins. 
More particularly, the present invention relates to polyetherimides which 
are melt crystalline. 
The polyetherimides form a now well-known class of engineering 
thermoplastic polymers. These polymers offer such attributes as high heat 
resistance, stiffness, impact strength and transparency, high mechanical 
strength, good electrical properties, high flame resistance, low smoke 
generation and broad chemical resistance. In addition to these important 
properties, the polyetherimides exhibit the ease of processability 
associated with traditional engineering thermoplastics, although in 
general higher melt temperatures are required. 
Polyetherimides are sold by the General Electric Company under the 
trademark Ultem.RTM.. Polyetherimide resins are of considerable commercial 
value for use in molding compositions because of the excellent physical, 
chemical and thermal properties mentioned above. The high glass transition 
and heat deflection temperatures exhibited by these polymers permit their 
use in high performance applications. The polyetherimides find 
applications in the automotive, aerospace and electrical industries, for 
example. 
It is well known and accepted by those skilled in the art that the 
conventional, commercially available polyetherimides exist in an amorphous 
state upon solidifying from the melt This is true of the polyetherimide 
resins commercially available from the General Electric Company under the 
ULTEM.RTM. trademark including ULTEM-1000 (a copolymer of bisphenol A 
dianhydride and meta-phenylene diamine), ULTEM-6000 (a copolymer of bis 
phenol A dianhydride, pyromellitic dianhydride and meta-phenylene diamine) 
and ULTEM-5001 (a copolymer of bisphenol A dianhydride and para-phenylene 
diamine). 
Various efforts have been made to improve even further the properties of 
polyetherimide resins. One approach to such improvements has been to 
prepare melt crystalline forms of the resins An increased solvent 
resistance is one example of an improvement that might be achieved by 
increasing the melt crystallinity of the resins. 
Examples of melt crystalline polyetherimides using exotic diamines are 
described by Takekoshi, et al., in Journal of Polymer Science, 74, pp. 
93-108 (1986). The use of an exotic diamine, 
1,3-bis(4-aminophenoxy)-benzene allowed certain polyetherimides to be melt 
crystalline and yielded higher solvent resistance to ordinary chemical 
reagents which are used for industrial purposes The disadvantages of these 
types of `exotic diamine` polyetherimides are scarcity and high price of 
the amines. 
It is one object of the present invention to provide melt crystalline 
polyetherimide resin compositions Another object of the invention is to 
provide such compositions which retain the ease of synthesis and 
processing associated with the commercially available amorphous 
polyetherimide resins. A further object of the invention is to provide 
melt crystallizable polyetherimide resin compositions having production 
costs permitting them to become commercially attractive to industry. 
SUMMARY OF THE INVENTION 
We have now discovered that polyetherimides including repeating units 
prepared from certain dianhydrides and diamines are highly crystalline in 
nature. We have also discovered that the substitution of even minor 
amounts of these crystalline polyetherimide repeating units within the 
polymer chains of known amorphous polyetherimide resins renders the 
modified composition crystalline. These crystalline polyetherimide 
materials exhibit extremely high thermal oxidative stability, heat 
distortion temperatures as well as extremely high solvent resistance The 
crystalline polyetherimides retain the processing ease of their amorphous 
counterparts and are useful as molding compounds and in the preparation of 
high strength fibers with excellent chemical and heat resistance. 
Conventional amorphous polyetherimide resin compositions begin to exhibit 
heat distortion at or slightly below their respective glass transition 
temperatures (T.sub.g). Heat distortion temperatures of the present 
compositions advantageously may lie well above their T.sub.g s, however. 
When properly reinforced with glass fiber, carbon fibers or mineral 
fillers, the heat distortion temperatures of the crystalline compositions 
could increase and approach their respective melting points (T.sub.m). For 
many compositions of the present invention this translates into about a 
60.degree. to 100.degree. C. increase in heat distortion temperature over 
corresponding amorphous polyetherimide resins. 
In one aspect, the present invention relates to melt crystalline 
polyetherimide resins comprising repeating units based on 
biphenoldianhydride and a linear aromatic diamine. In another aspect, the 
present invention relates to melt crystalline polyetherimide resins 
comprising repeating units based on hydroquinone dianhydride and a linear 
aromatic diamine. In other aspects, the present invention relates to 
specific melt crystalline polyetherimide resins comprising one or more of 
the aforementioned crystallizing repeating units. 
DETAILED DESCRIPTION 
The polyetherimides have been previously described in the literature as 
containing repeating groups of the formula 
##STR1## 
wherein "a" is a whole number greater than 1, e.g., from 10 to 10,000 or 
more; the group --O--A&lt; is selected from: 
##STR2## 
R' being hydrogen, lower alkyl or lower alkoxy, preferably a 
polyetherimide including the latter --O--A&lt; group where R' is hydrogen 
such that the polyetherimide is of the formula: 
##STR3## 
T is --O-- or a group of the formula 
EQU --O--Z--O-- 
wherein the divalent bonds of the --O-- or the --O--Z--O-- group are in the 
3,3'; 3,4'; 4,3', or the 4,4' position; Z is a member of the class 
consisting of (A): 
##STR4## 
and (B) divalent organic radicals of the general formula 
##STR5## 
where X is a member selected from the group consisting of divalent 
radicals of the formulas 
##STR6## 
where q is 0 or 1, y is an integer from 1 to about 5; and R is a divalent 
organic radical selected from the group consisting of (a) aromatic 
hydrocarbon radicals having from 6 to about 20 carbon atoms and 
halogenated derivatives thereof, (b) alkylene radicals having from 2 to 
about 20 carbon atoms, cycloalkylene radicals having from 3 to about 20 
carbon atoms, C.sub.2 to C.sub.8 alkylene- terminated 
polydiorganosiloxanes and (c) divalent radicals of the general formula 
##STR7## 
where Q is a member selected from the group consisting of 
##STR8## 
and y is a whole number from 1 to about 5, inclusive. 
Included among the many methods of making the polyetherimides are those 
disclosed in U.S. Pat. Nos. 3,847,867 (Heath et al.), 3,847,869 
(Williams), 3,850,885 (Takekoshi et al.), 3,852,242 and 3,855,178 (White) 
and 4,417,044 (Parekh) and others. These disclosures are incorporated 
herein in their entirety by reference for the purpose of teaching, by way 
of illustration, general and specific methods for preparing 
polyetherimides. 
Some of the aromatic bis(ether anhydride)s of formula (I) 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 by the hydrolysis, followed by 
dehydration, of the reaction product of a nitrosubstituted phenyl 
dinitrile with a metal salt of dihydric phenol compound in the presence of 
a dipolar, aprotic solvent. 
Additional aromatic bis(ether anhydride)s also included within formula (I) 
above are shown by Koton, M.M., Florinski, F.S., Bessonov, M.I. and 
Rudakov, A.P. (Institute of Heteroorganic Compounds, Academy of Sciences, 
U.S.S.R), U.S.S.R. patent 257,010, Nov. 11, 1969, Appl. May 3, 1967, and 
by M. M. Koton, F. S. Florinski, Zh. Org. Khin. 4(5), 774 (1968). 
We have now discovered that polyetherimides including even minor amounts of 
repeating units prepared from biphenoldianhydride (BPDA) and certain 
linear aromatic diamines, i.e. repeating units of formula: 
##STR9## 
and/or repeating units prepared from hydroquinone dianhydride (HQDA) and 
certain linear aromatic diamines, i.e. repeating units of formula: 
##STR10## 
wherein R.sup.1 is the residue of a linear aromatic diamine, are melt 
crystalline and exhibit the improved properties mentioned earlier. 
In each of formulas (II) and (III) (referred to herein as crystalline 
repeating units) the R.sup.1 moiety is the residue of a linear aromatic 
diamine. The term "linear" in this context means that the diamine is 
incorporated in a linear fashion within the linear polyetherimide chain. 
Examples of such linear diamines include para-phenylenediamine (pPD), 
2,6-diamino-naphthalene and 1,4-diaminonaphthalene. Paraphenylenediamine 
is preferred. 
Homopolymers consisting totally of repeating units of either Formula II or 
Formula III, while crystalline, have been found to be relatively 
intractable and infusible materials which are not melt processible. Thus, 
these homopolymers in and of themselves are not attractive for use in 
thermoforming processes. The incorporation of as little as five percent 
(mole percent basis) of one or both of these repeating units into the 
polymer chains of amorphous melt processible polyetherimide resins, 
however, renders the modified composition crystalline upon solidifying 
from the melt, improves solvent resistance and heat deflection, yet does 
not adversely impact upon the processing ease of the resins. The 
crystallizing repeating units of Formulas II and III can be incorporated 
into the polymer chain during synthesis by employing appropriate 
quantities of BPDA and/or HQDA and linear aromatic diamine(s), or 
derivatives thereof, in the reaction mixture. 
The present invention is not limited to the substitution of these 
crystalline repeating units within the polymer chains of commercially 
available amorphous polyetherimide resins. Melt crystalline polyetherimide 
resin compositions including various other constituents can be prepared 
via the conventional polymerization processes referenced herein with the 
proviso that the starting materials be chosen so as to result in a 
sufficiently high BPDA/linear aromatic diamine and/or HQDA/linear aromatic 
diamine content in the resin. In this manner a wide variety of melt 
crystalline polyetherimide resins can be prepared. The relative 
proportions of the various crystalline repeating units within the 
polyetherimide polymer chain can be selected via routine experimentation 
to obtain polymers having a desired degree of crystallinity. 
We have found that the incorporation of at least about five percent (mole 
percent basis) of these crystalline repeating units within the 
polyetherimide chain is required to impart a degree of crystallinity 
effective to meaningfully improve the properties of the resin. Preferably 
about five to 90 percent of these repeating units are incorporated within 
the polyetherimide chain. As mentioned earlier homopolymers of these 
subunits are not melt processible, thus the BPDA/linear aromatic diamine 
and/or HQDA/linear aromatic diamine content of the polymer should not 
exceed the point where processability is lost. Those skilled in the art 
can readily determine optimum content on a case by case basis. 
It is contemplated that the melt crystalline polyetherimides of the present 
invention may also include other additive materials such as fillers, 
stabilizers, plasticizers, flexibilizers, surfactant agents, pigments, 
dyes, reinforcement, flame retardants and diluents in conventional 
amounts. 
The role of reinforcing agents in the present melt crystalline polymers is 
especially important when it is desired to obtain maximum heat deflection 
properties. As is known in connection with other crystalline polymers, 
heat distortion temperatures exceeding the T.sub.g and approaching the 
T.sub.m may be obtained by properly reinforcing the polymer matrix. 
Examples include glass fibers, carbon fibers and mineral fibers.