Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2000-08-07
2001-07-24
Hampton-Hightower, P. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C528S125000, C528S126000, C528S128000, C528S171000, C528S172000, C528S173000, C528S174000, C528S175000, C528S179000, C528S182000, C528S183000, C528S185000, C528S188000, C528S214000, C528S215000, C528S219000, C528S220000, C528S229000, C528S351000, C528S352000, C528S353000
Reexamination Certificate
active
06265521
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to the preparation of polyether polymers, and more particularly to the preparation of polymers of closely controlled molecular weight by a simple and reliable method.
Various types of aromatic polyethers, including polyetherimides, polyethersulfones, polyetheretherketones, and polyetherketones, have become important as engineering resins by reason of their excellent properties. These polymers are typically prepared by the reaction of salts of dihydroxyaromatic compounds, such as bisphenol A disodium salt, with dihaloaromatic molecules such as bis(4-fluorophenyl) sulfone, bis(4-chlorophenyl) sulfone, the analogous ketones and bis(halophenyl)bisimides or bis(nitrophenyl)bisimides as illustrated by 1,3-bis[N-(4-chlorophthalimido)]benzene. Substantially equimolar proportions of the two reagents are normally required, with adjustment if desired for the presence of endcapping reagents such as 1-[N-(4-chlorophthalimido)]-3-(N-phthalimido)benzene.
According to U.S. Pat. No. 5,229,482, polyether polymers are prepared by the above-described reaction in a solvent of low polarity such as o-dichlorobenzene and in the presence of a catalytically active amount of a phase transfer catalyst which is substantially stable at the temperatures employed, such as a hexaalkylguanidinium halide. A similar method of preparation, employing a monoalkoxybenzene such as anisole as solvent, is described in U.S. Pat. No. 5,830,974.
One difficulty in the preparation of polyether polymers by this method is the preparation of polymers of controlled and desired molecular weights. Since very nearly equimolar proportions of the principal reagents are required in all instances, it is typically very difficult to predict or control the molecular weight of the polyether polymer. For example, polyetherimides having weight average molecular weights in the ranges of about 43,000-46,000 and about 50,000-55,000 may be desired by reason of their advantageous properties, but a given reaction may afford a product whose molecular weight is much higher or, more often, much lower. That product, being off specification, must be discarded, increasing the cost and size of the waste stream, with adverse consequences to the environment.
It is highly desirable, therefore, to develop a method for preparing polyether polymers which is adapted to the close control of molecular weight by relatively simple means.
SUMMARY OF THE INVENTION
The present invention is based on the discovery that it is possible to prepare an intermediate low molecular weight polyether polymer by withholding a portion of the dihydroxyaromatic compound salt in a first reaction step, and employing said intermediate polymer in a second step of reaction with further salt to produce a polymer of predetermined molecular weight. Further, the amount of further salt to be used in the second step can be determined from the molecular weight of the intermediate polymer.
In one embodiment the invention is a method for preparing a desired aromatic polyether polymer having a predetermined molecular weight which comprises:
(A) contacting, at a temperature and sufficiently dry state effective to promote a polymer-producing condensation reaction, at least one alkali metal salt of a dihydroxy-substituted aromatic hydrocarbon with at least one substituted aromatic compound of the formula
Z(A
1
−X
1
)
2
, (I)
wherein Z is an activating radical, A
1
is an aromatic radical and X
1
is fluoro, chloro, bromo or nitro, the proportion of said alkali metal salt being less than the total amount calculated to produce said desired polymer, thereby producing an intermediate low molecular weight polymer;
(B) determining the molecular weight of said intermediate polymer; and
(C) adding a further portion of at least one alkali metal salt, said further portion being calculated to produce said desired polymer and being in the range of about 0.2-8.0 mole percent of total alkali metal salt, and continuing said condensation reaction to produce said desired polymer.
DETAILED DESCRIPTION; PREFERRED EMBODIMENTS
At least one dihydroxy-substituted aromatic hydrocarbon is employed in the reaction. Suitable dihydroxy-substituted aromatic hydrocarbons include those having the formula
HO—A
2
—OH, (II)
wherein A
2
is a divalent aromatic hydrocarbon radical. Suitable A
2
radicals include m-phenylene, p-phenylene, 4,4′-biphenylene, 4,4′-bi(3,5-dimethyl)phenylene, 2,2-bis(4-phenylene)propane and similar radicals such as those which correspond to the dihydroxy-substituted aromatic hydrocarbons disclosed by name or formula (generic or specific) in U.S. Pat. No. 4,217,438.
The A
2
radical preferably has the formula
—A
3
—Y—A
4
—, (III)
wherein each of A
3
and A
4
is a monocyclic divalent aromatic hydrocarbon radical and Y is a bridging hydrocarbon radical in which one or two atoms separate A
3
from A
4
. The free valence bonds in formula III are usually in the meta or para positions of A
3
and A
4
in relation to Y. Compounds in which A
2
has formula III are bisphenols, and for the sake of brevity the term “bisphenol” is sometimes used herein to designate the dihydroxy-substituted aromatic hydrocarbons; it should be understood, however, that non-bisphenol compounds of this type may also be employed as appropriate.
In formula III, the A
3
and A
4
values may be unsubstituted phenylene or halo or hydrocarbon-substituted derivatives thereof, illustrative substituents (one or more) being alkyl, alkenyl, bromo, chloro. Unsubstituted phenylene radicals are preferred. Both A
3
and A
4
are preferably p-phenylene, although both may be o- or m-phenylene or one o- or m-phenylene and the other p-phenylene.
The bridging radical, Y, is one in which one or two atoms, preferably one, separate A
3
from A
4
. Illustrative radicals of this type are methylene, cyclohexylmethylene, 2-[2.2.1]-bicycloheptylmethylene, ethylene, isopropylidene, neopentylidene, cyclohexylidene, cyclopentadecylidene, cyclododecylidene and adamantylidene; gem-alkylene (alkylidene) radicals are preferred. Also included, however, are unsaturated radicals.
Also included among suitable dihydroxy-substituted aromatic hydrocarbons are the 2,2,2′,2′-tetrahydro-1,1′-spirobi[1H-indene]diols having formula IV:
wherein each R
1
is independently selected from monovalent hydrocarbon radicals and halogen radicals; each R
2
, R
3
, R
4
, and R
5
is independently C
1-6
alkyl; each R
6
and R
7
is independently H or C
1-6
alkyl; and each n is independently selected from positive integers having a value of from 0 to 3 inclusive. A preferred 2,2,2′,2′-tetrahydro-1,1′-spirobi[1H-indene]-diol is 2,2,2′,2′-tetrahydro-3,3,3′,3′-tetramethyl-1,1′-spirobi[1H-indene]-6,6′-diol.
Some preferred examples of dihydric phenols of formula II include 6-hydroxy-1-(4′-hydroxyphenyl)-1,3,3-trimethylindane, 4,4′-(3,3,5-trimethylcyclo-hexylidene)diphenol; 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane; 2,2-bis(4-hydroxyphenyl)propane (commonly known as bisphenol-A); 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane; 2,2-bis(4-hydroxy-3-methylphenyl)propane; 2,2-bis(4hydroxy-3-ethylphenyl)propane; 2,2-bis(4-hydroxy-3-isopropylphenyl)propane; 2,4′-dihyroxydiphenylmethane; bis(2-hydroxyphenyl)methane; bis(4-hydroxy-phenyl)methane; bis(4-hydroxy-5-nitrophenyl)methane; bis(4-hydroxy-2,6-dimethyl-3-methoxyphenyl)methane; 1,1-bis(4-hydroxyphenyl)ethane; 1,1-bis(4-hydroxy-2-chlorophenyl)ethane; 2,2-bis(3-phenyl-4-hydroxyphenyl)-propane; bis(4-hydroxyphenyl)cyclohexylmethane; 2,2-bis(4-hydroxyphenyl)-1-phenylpropane; resorcinol; C
1-3
alkyl-substituted resorcinols. For reasons of availability and particular suitability for the purposes of this invention, the preferred dihydric phenol is bisphenol A in which the radical of formula III is the 2,2-bis(4-phenylene)propane radical and in which Y is isopropylidene and A
3
and A
4
are each p-phenylene.
Th
Fyvie Thomas Joseph
Howson Paul Edward
Kailasam Ganesh
Phelps Peter David
Rohr Donald Frank
Brown S. Bruce
General Electric Company
Hampton-Hightower P.
Johnson Noreen C.
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