Quaternary Group VA salt catalyzed method for making polyetherimide

A method is provided for making polyetherimides, based on the use of certain quaternary Group VA salts, for example tetra-alkylammonium halides, to accelerate the intercondensation of aromatic bis(ether anhydride) and organic diamine under solution or melt polymerization conditions. The resulting polyetherimides are high performance, injection moldable thermoplastics.

CROSS REFERENCE TO RELATED APPLICATIONS 
Reference is made to our copending applications Ser. No. 190,613, filed 
Sept. 25, 1980. Organic Amine Catalyzed Method for Making Polyetherimide, 
Ser. No. 118,756, filed Sept. 19, 1980, A Method for Making 
Polyetherimide, RD-12236, Method for Making Polyetherimides and Takekoshi, 
Ser. No. 118,755, filed Sept. 19, 1980, A Method for Making Polyimides, 
where all of the aforementioned applications are assigned to the same 
assignee as the present invention. 
BACKGROUND OF THE INVENTION 
The present invention relates to a method for making polyetherimides by 
effecting reaction between aromatic bis(ether anhydride) and an organic 
diamine under solution polymerization conditions. More particularly, the 
present invention relates to the use of certain quaternary salts of Group 
Va elements as polymerization catalysts for making aromatic 
polyetherimides. 
Prior to the present invention, certain catalysts, such as sodium chloride 
and ferric sulfate, as shown by Williams et al, U.S. Pat. No. 3,998,840, 
assigned to the same assignee as the present invention, were used to 
enhance the rate of formation of polyetherimide under melt polymerization 
conditions. Although valuable results were achieved by such procedures, it 
was found that the aforementioned catalysts were either less effective or 
not effective when utilized for making polyetherimides from aromatic 
bis(ether anhydride) and organic diamine under solution polymerization 
conditions. In addition, the presence of chloride ion may interfere with 
the use of such polyetherimide in electrical applications. Various metal 
compounds were also used to catalyze polyetherimide formation by 
imideamine exchange reactions, as shown by U.S. Pat. No. 3,847,870, 
Takekoshi and U.S. Pat. No. 3,850,885, Takekoshi et al, assigned to the 
same assignee as the present invention. However, the nature of the 
polymerization is quite different from polyetherimide formation by the 
melt polymerization of aromatic bis(ether anhydride) and organic diamine, 
which is amine-anhydride interaction rather than imide-amine exchange. 
Statement of the Invention 
The present invention is based on the discovery that certain quaternary 
salts of Group Va elements, for example, tetraalkyl ammonium halides, 
trialkylammonium hydrohalides and tetraphenylphosphonium halides, etc., 
can enhance the rate of formation of such aromatic polyetherimides 
resulting from aromatic bis(ether anhydride) and organic diamine 
interaction under melt polymerization or solution polymerization 
conditions when such Group VA catalysts are utilized in an effective 
amount in the polymerization mixture. 
There is provided by the present invention, a method for making aromatic 
polyetherimide which comprises, 
(1) effecting reaction between a C.sub.(6-30) aromatic bis(ether anhydride) 
and a C.sub.(2-20) aromatic diamine in the presence of an effective amount 
of an quaternary salt catalyst of a Group Va element selected from the 
class consisting of nitrogen and phosphorous, and 
(2) recovering the aromatic polyetherimide from the mixture of (1). 
Among the aromatic organic dianhydrides which can be utilized in the 
practice of the invention are aromatic bis(ether anhydride)s of the 
formula, 
##STR1## 
where R is a divalent aromatic organic radical having from 6-30 carbon 
atoms. In addition to the aromatic bis(ether anhydride)s of formula (1) 
there also can be used other aromatic bisanhydrides, for example, 
##STR2## 
Organic diamines which can be utilized in the practice of the invention are 
included by the following formula, 
EQU H.sub.2 NR.sup.1 NH.sub.2 ( 2) 
where R.sup.1 is a divalent organic radical selected from R radicals, 
alkylene radicals having from 2-20 carbon radicals, cyclo alkylene 
radicals and C.sub.(2-8) alkylene terminated polydiorganosiloxane 
radicals. 
Radicals included by R are, for example, aromatic hydrocarbon radicals and 
halogenated aromatic hydrocarbon radicals, for example, phenylene, 
tolylene, chlorophenylene, napthalene, etc., and radicals included by the 
formula, 
EQU --R.sup.2 --(Q).sub.a --R.sup.2 -- 
where R.sup.2 is a divalent aromatic radical having 6-13 carbon atoms 
selected from hydrocarbon radicals and halogenated hydrocarbon radicals, 
and Q is a divalent organo radical selected from --C.sub.y H.sub.2y --, 
##STR3## 
where a is 0 or 1, y is an integer having a value of from 1-5 inclusive, 
and R.sup.3 is a monovalent hydrocarbon radical selected from methyl, 
phenyl, etc. 
Radicals included by R.sup.1 are, for example, 
##STR4## 
etc.; alkylene radicals such as hexamethylene, etc., cyclohexylene, 
##STR5## 
where R.sup.3 is as defined above, m is equal to 0 to 100 inclusive and n 
is 2-8 inclusive. 
Included by the aromatic bis(ether anhydride) of formula (1) which can be 
used in the practice of the present invention are, for example, 
##STR6## 
where R is as defined above. 
Dianhydrides included by formula (4) are, for example, 
2,2-bis[4-(2,3-dicarboxyphenoxy)phenyl]propane dianhydride; 
4,4'-bis(2,3-dicarboxyphenoxy)diphenyl ether dianhydride; 
1,3-bis(2,3-dicarboxyphenoxy)benzene dianhydride; 
4,4'-bis(2,3-dicarboxyphenoxy)diphenylsulfide dianhydride; 
1,4-bis(2,3-dicarboxyphenoxy)benzene dianhydride; 
4,4'-bis(2,3-dicarboxyphenoxy)diphenylsulfone dianhydride; etc. 
Dianhydrides included by formulas (3) and (5) are, for example, 
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; 
1,3-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. 
Included by the organic diamines of formula (2) are, for example, 
m-phenylenediamine; 
p-phenylenediamine; 
4,4'-diaminodiphenylpropane; 
4,4-diaminodiphenylmethane; benzidine; 
4,4'-diaminodiphenylsulfide; 
4,4'-diaminodiphenylsulfone; 
4,4'-diaminodiphenyl ether; 
1,5-diaminonapthalene; 
3,3'-dimethylbenzidine; 
3,3'-dimethoxybenzidine; 
2,4-bis(.beta.-amino-t-butyl)toluene; 
bis(p-.beta.-amino-t-butylphenyl)ether; 
bis(p-.beta.-methyl-o-aminopentyl)benzene; 
1,3-diamino-4-isopropylbenzene; 
1,2-bis(3-aminopropoxy)ethane; 
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; etc. 
Quaternary Group Va catalysts which have been found to be in the practice 
of the method of the present invention are, for example, 
tributylmethylammonium benzoate; 
tetramethylammonium benzoate; 
tetrabutylammonium benzoate; 
tetrabutylammonium acetate; 
bis(tetramethylammonium)phthalate; 
bis(tetraethylammonium)phthalate; 
bis(tetrabutylammonium)phthalate; 
tris(tetrabutylammonium)trimellitate; 
tetrabutylammonium chloride; 
tributylammonium chloride; 
tetraphenylphosphonium bromide; 
bis(tetraphenylphosphonium)isophthalate; 
tetrabutylphosphonium benzoate; 
tetrabutylarsonium benzoate; 
tetrabutylstibonium bromide, etc. 
In the practice of the present invention, reaction can be effected between 
an organic dianhydride and an organic diamine in the presence of the Group 
Va salts which hereinafter will represent the aforedescribed 
tetralkylammonium halides, trialkylammonium hydrohalides, etc., under 
solution polymerization conditions at a temperature in the range of from 
130.degree. C. to 300.degree. C. or under melt polymerization conditions 
at a temperature in the range of from 250.degree. C. to 350.degree. C. 
In instances where solution polymerization is practiced, there can be 
utilized various organic solvents, for example, 
chlorobenzene; 
o-dichlorobenzene; 
m-dichlorobenzene; 
1,2,4-trichlorobenzene; 
4-chlorotoluene; 
bromobenzene; 
biphenyl; 
phenyl ether, etc. 
It has been found that a proportion of from about 0.9 to 1.1 moles of 
organic diamine, per mole of organic dianhydride can be used, while 
substantially equal molar amounts of such reactants along with appropriate 
quantities of chain-stoppers, such as aniline or phthalic anhydride, are 
preferred. The solids concentration of at least 10% by weight to 50% by 
weight during solution polymerization has been found to be effective. 
Group Va catalyst can be used at a concentration of from 0.2 to 5% by 
weight, based on the weight, based on the weight of total solids in the 
polymerization mixture and vary within this range, depending upon the 
particular structure of the Group Va catalyst used. 
Reaction times can vary widely depending upon the particular aromatic 
organic dianhydride and organic diamine utilized, as well as the 
temperature of the reaction. However, an enhancement of the rate of 
reaction will be effected and readily discernable as the result of the use 
of the amine catalyst. 
In instances where melt polymerization is employed, substantially similar 
proportions of reactants and catalysts as described above for solution 
polymerization can be utilized in the absence of organic solvent. Melt 
polymerization can be achieved satisfactorily in a melt extruder, as 
taught, for example, by Mellinger et al, U.S. Pat. No. 4,073,773. 
The polyetherimides made in accordance with the practice of the present 
invention can be employed as high performance injection moldable 
thermoplastics. Depending upon the nature of the organic dianhydride and 
the organic diamine utilized, the resulting polyimides also can be 
utilized in a variety of other applications, for example, insulation, 
films, wire coatings, glass and graphite fiber composites, laminates, etc.

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 163 parts of o-dichlorobenzene, 67.66 parts of 
2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, 13.64 parts of 
metaphenylene diamine, 0.72 part of aniline and 0.80 part of Group Va 
catalyst was stirred under a nitrogen atmosphere and immersed in an oil 
bath preheated to 145.degree. C. The oil bath was then heated over a 60 
minute time period to 195.degree. C. 
Within 5 minutes of the start of the reaction, precipitation of an 
intermediate reaction product was noted. With increased stirring, the 
solids began to go back into solution and evolution of water was noted. 
After 60 minutes, the o-dichlorobenzene began to reflux and aliquots of 
mixture were removed for GPC analysis. Additional samples were taken at 
intervals of 0.5, 2, 4, 6 and 22 hours. 
A portion of each sample was diluted with chloroform immediately upon 
removal from the reaction mixture for GPC analysis. The remainder of each 
sample was diluted with chloroform and precipitated from solution with a 
10 fold volume of methanol, followed by filtration, washing the 
precipitate and drying. 
Some of the Group Va salts utilized as catalyst as shown in the Table below 
were prepared from tetra-alkylammonium hydroxide with an appropriate 
aromatic acid, for example, benzoic acid compound (III), phthalic acid (I) 
and isophthalic acid (II). Compounds (II) and (III) were prepared as 
follows: There was added 0.02 moles of aqueous tetra-butylammonium 
hydroxide in the form of a 40.7% aqueous solution to 0.01 mole of the 
appropriate phthalic acid. Additional water was added to facilitate 
dissolving of the acid. The resulting mixture was warmed on a steam bath 
for 5 minutes then evaporated to dryness on a rotary evaporator. In the 
following Table, weight percent is based on the weight of the anticipated 
polyetherimide: 
TABLE I 
______________________________________ 
Catalyst --Mw (.times. 10.sup.-3).sup.a at time 
[.eta.] at time 
Compound 
WT % .5 hr 1 hr 2 hr 4 hr 6 hr 1 hr 6 hr 
______________________________________ 
Control 0.0 7 10 14 20 23 .24 .35 
I.sup.b,c 
3.0 8 10 14 22 29 .22 .42 
I.sup.b,c 
1.0 17 20 23 29 26 .32 .46 
I.sup.b 0.1 16 18 19 20 24 .34 .38 
I.sup.d 1.0 18 22 25 28 27 .36 .43 
I.sup.d 0.1 17 17 22 22 21 .25 .33 
II 1.0 24 26 28 28 31 .48 .48 
II 0.1 12 16 20 22 25 .32 .41 
III 0.3 21 25 26 26 29 .44 .48 
III .1 15 19 23 23 24 .33 .35 
III .05 14 17 19 19 25 .33 .36 
Bu.sub.4 NCl 
1.0 18 21 26 28 28 .38 .46 
.phi..sub.4 PBr 
1.0 -- -- -- -- -- .33 .47 
Bu.sub.3 N . HCl 
1.0 26 25 25 28 31 .43 .47 
" 0.1 -- 14 -- -- 23 .25 .39 
Benzoic 0.1 -- 14 -- -- 19 .23 .31 
Acid 
______________________________________ 
.sup.a --Mw by GPC with polystyrene calibration corrected to 
polyetherimide by a Q factor of 0.60. 
.sup.b Added in aqueous solution. 
.sup.c Catalyst used as chain terminator. 
.sup.d Used along with phthalic anhydride as chain terminator. 
EXAMPLE 2 
A mixture of 65.6 parts of 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane 
dianhydride, 14.06 parts of meta-phenylene diamine and 1.155 part of 
phthalic anhydride was dry blended in a Waring blender. A mixture of 10 
parts of the blend and 0.02 part of the Group Va catalyst was blended 
further and then heated in an open glass tube in an aluminum block which 
was being heated from 265.degree. C. to 280.degree. C. over a 10 minute 
period. During this period, the temperature of the mixture rose to 
280.degree. C. The resulting product was then dissolved in chloroform to 
form a 5% solution and precipitated with 5 volumes of methanol. The 
resulting product was then washed and dried and then analyzed by GPC. 
The following results were obtained: 
TABLE II 
______________________________________ 
Group VA 
Catalyst WT % --Mw .times. 10.sup.-3 ** 
______________________________________ 
Control None 17 
Tetrabutylammonium 
0.5 22 
benzoate* 
______________________________________ 
*Added as a 33% aqueous solution 
**Weight average molecular weight based on PS calibration corrected to 
polyetherimide. 
The above results show that the Group Va catalyst of the present invention 
is an effective polymerization catalyst under melt polymerization 
conditions. 
Although the above examples are directed to only a few of the very many 
variables within the scope of the present invention, it should be 
understood that the present invention is directed to the use of a much 
broader variety of organic dianhydrides and organic diamines and Group Va 
catalysts.