Process for capping quinone-coupled polyphenylene oxides

A process is disclosed which provides for an increase in the oxidative and/or thermal stability of quinone coupled polyphenylene oxides which comprises contacting quinone-coupled polyphenylene oxides with a capping agent in the presence of a water soluble base, and a catalytic phase transfer agent. The resulting new polymers have improved color and in combination with styrene resins provide thermoplastic compositions having improved chemical and physical properties.

Cross Reference to Related Applications 
This invention is related to subject matter disclosed in our copending U.S. 
application Ser. Nos. 800,646, 800,647 and 800,648, all filed on May 26, 
1977. All of the aforesaid applications are also our inventions and are 
assigned to the same assignee as the assignee of this application. All of 
the disclosures referenced above are incorporated herein in their entirety 
by reference. 
BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to the process for increasing the oxidative and/or 
thermal stability of quinone-coupled polyphenylene oxides by contacting 
the quinone-coupled polyphenylene oxides with a capping agent in the 
presence of a water soluble base and a catalytic phase transfer agent. 
2. Description of the Prior Art 
Hay et al., U.S. Ser. No. 613,072, now U.S. Pat. No. 4,048,143, discloses 
the capping of polyphenylene oxides having an average hydroxyl group per 
molecule of 1.0 or less as described in various U.S. patent applications 
including Hay's U.S. Pat. Nos. 3,306,879, 3,914,266; application Ser. No. 
540,473, filed Jan. 13, 1975, now U.S. Pat. No. 4,028,341; a 
continuation-in-part of Ser. No. 441,295, filed Feb. 11, 1974, now 
abandoned; and Olander's U.S. Pat. Nos. 3,956,442, 3,965,069, 3,972,851; 
and Ser. No. 582,910, filed June 2, 1975, now U.S. Pat. No. 4,054,553. All 
the Hay and Olander disclosures referenced above are incorporated herein 
in their entirety by reference. 
In White's copending U.S. patent application Ser. No. 800,635, filed on May 
26, 1977, new polyphenylene oxide quinone-coupled polymers having an 
average hydroxyl group per molecule value greater than 0, including 2.0 or 
less are described. These new polymers either alone or in combination with 
polyphenylene oxide reaction products of the prior art, i.e. polyphenylene 
oxides having an average hydroxyl group per molecule value greater than 
zero including 1.0 or less can be capped as described in greater detail 
hereafter to form other polymers having increased oxidative and thermal 
stability. 
DESCRIPTION OF THE INVENTION 
This invention embodies a process for increasing the oxidative and/or 
thermal stability of quinone-coupled polyphenylene oxides by contacting 
the quinone-coupled polyphenylene oxides with a capping agent in the 
presence of the water soluble base and a catalytic phase transfer agent. 
Broadly, the quinone-coupled polyphenylene oxides employed in my process 
are illustrated by the formula 
##STR1## 
wherein independently each --OZO-- is a divalent quinone residue, Z is a 
divalent arene radical, either a or b is at least equal to 1, the sum of a 
plus b is preferably at least equal to 10, more preferably 40 to 170, R' 
is hydrogen, a hydrocarbon radical, a halohydrocarbon radical having at 
least 2 carbon atoms between the halogen atoms and phenol nucleus, a 
hydrocarbonoxy radical, or a halohydrocarbonoxy radical having at least 
two carbon atoms between the halogen atoms and phenol nucleus, R" being 
the same as R' and, in addition, halogen. A presently preferred 
quinone-coupled polyphenylene oxide is of formula (I) above wherein 
independently each R' is hydrogen, a hydrocarbon radical, a 
halohydrocarbon radical, and even more preferably is a methyl radical, R" 
being hydrogen. 
Broadly, the quinone-coupled polyphenylene oxides can be prepared as 
described in our copending U.S. application Ser. No. 800,646, referenced 
hereinbefore. 
Broadly, the capping agents that can be employed in our process are 
illustrated by the following formulae: 
##STR2## 
including mixtures thereof, wherein R is alkyl, cycloalkyl, aryl or 
mixtures thereof, such as alkaryl, alkcycloalkyl, aralkyl, arcycloalkyl, 
cycloalkaryl, etc., and X is chlorine, bromine, fluorine or iodine. 
Preferably, the R groups contain from about 1 to about 30 carbon atoms, 
and more preferably contain from about 1 to about 20 carbon atoms. 
Representative examples of specific capping agents include the following: 
(A) monoacyl halides of formula (II) above, e.g. acetyl fluoride, acetyl 
chloride, acetyl bromide, the propionyl halides, butyryl halide, stearoyl 
halides, benzoyl chloride, toluoyl halides, naphthoyl halides, cinnamoyl 
halides, etc.; 
(B) monsulfonyl halides of formula (III) above, e.g. methanesulfonyl 
chloride, benzenesulfonyl halides, toluene sulfonyl bromide, xylene 
sulfonyl halides, etc.; 
(C) anhydrides of monocarboxylic acids of formula (IV) above, e.g. acetic 
anhydride, propionic anhydride, octanoic anhydride, benzoic anhydride, 
toluic anhydride, butyric anhydride, pivalic anhydride, m-dichlorobenzoic 
anhydride, 2,3,4,5,6-tentachlorobenzoic anhydride, pentaoic anhydride, 
palmatoic anhydride, stearic anhydride, etc.; 
(D) alkyl halides of formula (V) above, e.g. methylchloride, methylbromide, 
methyliodide, isopropyl halides, amyl halides, hexadecyl halides, 
cyclopentyl halides, 1-halo-1, 3-dimethylcyclopentanes, 
diphenyldihalomethanes, triphenyl halomethanes, etc.; and 
(E) dialkylsulfates of formula (VI) above, e.g. dimethyl sulfate, diethyl 
sulfate, dibutyl sulfate, diisoamyl sulfate, dicyclohexyl sulfate, 
didodecyl sulfate, di(octadecyl) sulfate, etc. A presently preferred 
capping agent is acetic anhydride since it is a readily available 
inexpensive capping agent. 
Our process is carried out by introducing a capping agent to a solution of 
a quinone-coupled polyphenylene oxide under fluid mixing conditions 
wherein the liquid reaction medium experiences high fluid shear stress 
since our process is highly sensitive to the dispersion of the reactants. 
In a preferred embodiment, the capping reaction is carried out while 
introducing the acyl halide to the quinone-coupled polyphenylene oxide 
solution at a point or region within a reaction environment near a mixing 
impeller, e.g. an axial-flow or radial flow impeller, such as a 
marine-type mixing propeller, fan turbine, pitched paddle, curved blade 
turbine, spiral backswept turbine, flat-blade turbine, gate impeller, 
anchor impeller, etc., in order to establish and maintain high fluid shear 
rates and accordingly relatedly high fluid shear stresses. The addition of 
acyl halide under the aforesaid process conditions facilitates the 
establishment and maintenance of a substantially uniform dispersion of 
reactants, acyl halide, quinone-coupled polyphenylene oxide, water soluble 
base, and catalytic phase transfer agent, and accordingly optimum process 
efficiency. In general, process equipment employing high-speed axial-flow 
impeller mixers are presently preferred in our process. 
Advantageously and preferably, our process is carried out employing 
substantially the exact stoichiometric amounts of acyl halide required to 
completely cap essentially all of the hydroxyl components associated with 
the quinone-coupled polyphenyl oxide reactants. Preferably the acyl halide 
is added to the reaction medium continuously during the course of the 
reaction so that the exact stoichiometric acyl halide requirements for 
completion of the capping reaction are only satisfied as the last portion 
of acyl halide is added to the reaction medium. 
In a preferred embodiment, our process is carried out in the substantial 
absence of any hydrolyzing agent, e.g. water methanol, etc., or other 
chemical constituents which can promote undesirable side reactions, such 
as primary or secondary amines. Accordingly, it is highly desirable that 
the individual and preferably the collective water, methanol, etc., 
primary and secondary amine content be limited to less than 1%, and more 
preferably less than 1/2% based on the weight of quinone-coupled 
polyphenylene oxide reactant. 
The acyl halide coupling reaction is carried out in the presence of water 
soluble base, preferably in solution in an aqueous phase. The water 
soluble base can be any water soluble base which, in the presence of 
polyphenylene oxides, can convert substantially all of the hydroxy groups 
associated therewith to phenoxides, i.e. alkali metal or alkaline earth 
metal cation phenoxides or "onium" phenoxides derived from catalytic phase 
transfer agents described in greater detail later herein. Further 
illustrative of the bases that can be employed are alkali metal or 
alkaline earth metal hydroxides and carbonates, e.g. potassium hydroxide, 
sodium hydroxide, sodium monocarbonate, barium carbonate, etc. In general, 
any amount of water soluble base can be employed, e.g. 0.1 to about 1000, 
preferably 1 to about 20, and more preferably 1.5 to about 5 moles of base 
per hydroxyl group associated with the polymers as identified by hydroxyl 
group infrared absorption at 3610 cm..sup.-1 based on a 2.5% solution in a 
CS.sub.2 over a 1 cm. path calibrated against CS.sub.2 in a matched cell. 
Further, preferably, the water soluble base is employed in solution in an 
aqueous phase wherein the water soluble base content is at least 10% and 
more preferably at least 25-50% by weight of the aqueous base solution. 
Preferably the acyl halide capping reaction is carried out in the presence 
of a catalytic phase transfer agent. The agent can be any phase transfer 
agent known to those skilled in the art, e.g. quaternary ammonium 
compounds, quaternary phosphonium, tertiary sulfonium compounds, etc., 
including mixtures thereof. Presently preferred phase transfer agents can 
be described by the formulae: 
##STR3## 
wherein each R' is independently selected from aliphatic hydrocarbon 
radicals having from about 1 to about 30 carbon atoms, preferably from 
about 2 to about 15 carbon atoms, each Y.sup.- is selected from the group 
consisting of Cl.sup.-, Br.sup.-, F.sup.-, CH.sub.3 SO.sub.3.sup.-, 
CH.sub.3 CO.sub.2.sup.-, CF.sub.3 CO.sub.2.sup.- or OH.sup.- , and each 
Y.sup.-- is selected from the group consisting of SO.sub.4.sup.--, 
CO.sub.3.sup.--, or C.sub.2 O.sub.4.sup.--. The catalytic phase transfer 
agents can also be employed in any amount, e.g. in amounts of from 0.001 
to 10, preferably from 0.01 to 1.0, and more preferably from 0.05 to 0.5 
moles based on the molar amounts of hydroxyl groups associated with the 
polymer. 
Broadly, reaction time can be any time, e.g. 1/10 hour or less, to 10 
hours, or more. Broadly, the reaction temperature can be any temperature, 
e.g. 0.degree. C. or less to 150.degree. C. or more. Broadly, the reaction 
pressures can be any pressure, e.g. subatmospheric, atmospheric or 
superatmospheric. Preferably, the reaction is carried out under optimum 
time, temperature and pressure reaction conditions which integrates 
substantially all, e.g. 90- 99% or more of the acyl halide contained 
within the reaction medium into the polymer backbone during the process. 
Broadly, the acyl-capped quinone-coupled polyphenylene oxides can be 
isolated from the reaction medium by any means employed heretofore to 
isolate the polymer produced by the processing of Hay and Orlander. 
Preferably, the products of our process are isolated from the reaction 
medium by spray drying, steam precipitation or any other method which 
avoid costly distillation procedures involved in the separation by 
distillation of mixed solvents.

In order that those skilled in the art may better understand my invention, 
the following example is given which is illustrated with the best mode of 
practicing our invention. 
EXAMPLE I 
(A) Polymer Preparation 
A 2.5 gallon stainless steel reactor equipped with an air-driven paddle 
stirrer, oxygen inlet tube, and water-cooled coil and jacket was charged 
with 5.48 l. toluene, 121.2 ml. of a stock catalyst solution, i.e. (29.5 
ml. bromine added slowly to a chilled solution of 7.76 g. cuprous oxide 
and 132.0 g. 2,6-xylenol in methanol, then diluted to 1.0 l.), 4.51 g. 
N,N'-di(t-butyl)ethylenediamine (DBEDA), 26.5 g. N,N-dimethylbutylamine 
(DMBA), and 16.0 g. di(n-butyl)amine (DBA). Oxygen was bubbled into the 
resulting admixture at a rate of 10 SCFH while vigorously agitating the 
admixture, 1600 g. of 2,6-xylenol dissolved in 1.8 l. toluene was pumped 
into the reactor over a 30 minute period. Summarily, the reaction 
prameters relative to molar ratios of 2,6-xylenol:Cu:DBEDA:DMBA:Br:DBA 
were as follows: 1000:1:2:20:8:9.4. The reaction temperature was 
maintained at 25.degree. C. throughout the monomer addition, and was 
increased to and maintained at 40.degree. C. until the reaction was 
terminated. 
(B) Catalyst Deactivation 
The reaction was terminated after 58 minutes (measured from start of 
monomer addition) by replacing oxygen with nitrogen and the addition of 
16.0 ml. 38% Na.sub.3 EDTA in water. Polymer analysis showed an [.eta.] 
equal to 0.59 dl./g. and an OH absorbance of 0.042 units. 
(C) Quinone Coupling 
The resulting TMDQ containing reaction mixture was heated under nitrogen at 
50.degree. to 60.degree. C. for 30 minutes and then at 95.degree. C. for 
15 minutes. At this point the mixture no longer exhibited the 
characteristic TMDQ color. Polymer analysis after methanol precipitation, 
washing and drying the polymer sample collected on a filter, washed with 
methanol and dried in a circulating air oven at 80.degree. C. showed an 
[.eta.] equal to 0.53 dl./g., and an OH absorbance of 0.139 units. 
(D) Capping 
(1) One-half of the resulting quinone-coupled polyphenylene oxide reaction 
mixture was cooled to 60.degree. C., transferred to a 2.5 gallon stainless 
steel reactor equipped with a high-shear stirrer (Polytron homogenizer), 
nitrogen inlet tube and heating coils. 35.5 ml. of a 10% solution of 
Aliquat.RTM. 336 in toluene and 16.7 g. 50% aqueous NaOH was added. The 
mixture was stirred vigorously under nitrogen for 2 minutes and then 19.7 
ml. acetic anhydride in 30 ml. toluene was added over a 3 minute period. 
The reaction mixture was diluted with an equal volume of toluene, washed 
with an equal volume of water and passed through a liquid-liquid 
centrifuge to remove the aqueous phase. Methanol was added to precipitate 
the acetate capped polymer. Polymer analysis after methanol washing and 
drying showed an intrinsic viscosity [.eta.] equal to 0.53 dl./g. as 
measured in chloroform at 25.degree. C., a hydroxyl end group infrared 
absorbtion at 3610 cm..sup.-1 of 0.004, and a nitrogen content of 1038 
ppm. 
(2) The remaining half of the resulting quinone-coupled polyphenylene oxide 
reaction mixture was acetylated and washed as described in (D)(1) above, 
then isolated by steam precipitation by spraying the capped 
quinone-coupled polyphenylene oxide reaction mixture with steam through a 
nozzle into water at 95.degree. C. at a rate sufficient to provide rapid 
azeotropic removal of toluene and other materials such as amines. The 
steam precipitated solid polymer is collected on a filter, washed with 
additional water and dried at 90.degree. C. in a circulating air oven. 
Polymer analysis showed an intrinsic viscosity [.eta.] equal to 0.53 
dl./g., and OH absorbance at 3610 cm..sup.-1 of 0.001 units, in a nitrogen 
content of 1267 ppm. 
A summary of polymer processing and results are set out in Table I 
hereafter: 
TABLE I 
__________________________________________________________________________ 
OH 
Reaction 
[.eta.] 
Absorbance 
Process Step(s) Temp. .degree.C. 
dl./g. 
at 2610 cm..sup.-1 
__________________________________________________________________________ 
(A) 
Polymer Preparation, and 
(B) 
Catalyst Deactivation 
25-40 0.59 
0.042 
(C) 
Quinone Coupling 
50-95 0.53 
0.139 
(D) 
Capping 60 
(1) Methanol precipitation 
0.53 
0.004 
(2) Steam precipitation 
0.53 
0.001 
__________________________________________________________________________ 
As illustrated by the foregoing examples, anhydrides of monocarboxylic 
acids can be reacted effectively with quninone-coupled polyphenylene 
oxides. Analogous results are obtained wherein other anhydrides of 
monocarboxylic acids or any of the monoacyl halides, the monosulfonyl 
halides, the alkyl halides, or the dialkylsulfates described hereinbefore 
are employed in our process. 
Acyl capped quinone-coupled polyphenylene oxides prepared by our process 
can have any intrinsic viscosity and any number average molecular weight 
M.sub.n. Presently preferred polymers generally have an M.sub.n value of 
5,000 to 60,000, more preferably 15,000 to 30,000, having generally 
corresponding intrinsic viscosities of 0.17 to 1.7, and 0.4 to 0.7, 
respectively. 
The polymers of this invention can be combined with other fillers, 
modifying agents, etc., such as dies, pigments, stabilizers, flame 
retardant additives with beneficial results.