Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2001-11-02
2002-12-31
Hampton-Hightower, P. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S420000, C525S432000, C525S436000, C528S125000, C528S126000, C528S128000, C528S170000, C528S171000, C528S172000, C528S173000, C528S174000, C528S176000, C528S183000, C528S185000, C528S188000, C528S220000, C528S229000, C528S350000, C528S351000, C528S353000
Reexamination Certificate
active
06500904
ABSTRACT:
BACKGROUND OF INVENTION
The present invention relates generally to poly(imide)s and, more particularly, to high molecular weight poly(imide)s and methods of synthesis thereof.
Specialized applications of poly(imide)s capitalize on their unique chemical and physical properties, such as chemical resistance, selective gas permeability, good thermo-oxidative stability, excellent adhesion to metals, high heat performance, and mechanical strength. Poly(imide)s are particularly useful in certain specialized applications, for example in textiles, membranes with selective gas permeability, and in aerospace, aircraft, automotive, and related industries. Manufacture of certain of these articles (particularly selective gas permeable membranes) depends on the solubility and solution properties of the poly(imide). Accordingly, manufacture is preferably being based on solutions having high viscosities and low solid content. Although poly(imide)s having molecular weights of up to 50,000 Daltons are presently used, poly(imide)s having very high molecular weights, (especially greater than 100,000 Daltons) would be even more desirable, as high molecular weight poly(imide)s have high intrinsic viscosities, generally greater than about 0.75 deciliters per gram in the condensed (molten) phase. However, because of these very high viscosities, synthesis and isolation of high molecular weight poly(imide)s using techniques and equipment developed for use with lower molecular weight poly(imide)s is prohibitively difficult.
SUMMARY OF THE INVENTION
The above-described drawbacks and disadvantages are overcome by a method for the synthesis of a high molecular weight poly(imide) comprising coupling a first poly(imide) precursor having first a functional group and a weight average molecular weight less than about 50,000 Dalton with a second poly(imide) precursor having a second functional group and a weight average molecular weight less than about 50,000 Daltons to form a high molecular weight poly(imide) having a weight average molecular weight greater than 50,000 Daltons.
In an alternate embodiment, a method for the synthesis of a high molecular weight poly (imide) comprises coupling an amine-functionalized precursor poly(imide) having a weight average molecular weight of less than about 50,000 Daltons with an anhydride-functionalized precursor poly(imide) having a weight average molecular weight of less than about 50,000 Daltons to provide a poly(imide) having a molecular weight of greater than 50,000 Daltons. The above-described and other features and advantages will be appreciated and understood by those skilled in the art from the following detailed description and appended claims.
DETAILED DESCRIPTION
High molecular weight thermoplastic poly(imide)s are available from the coupling of lower molecular weight functionalized precursor poly(imide)s. As used herein,“high molecular weight poly(imide)s” refers to poly(imide)s having weight average molecular weights (M
W
) of greater than 50,000 Daltons, as measured by gel permeation chromatography/laser light scattering/differential viscometry. The method comprises coupling precursor poly(imide)s having complementary functional groups having a weight average molecular weight of less than about 50,000 Daltons. Preferably the method comprises coupling an amine-functionalized precursor poly(imide) having a weight average molecular weight of less than about 50,000 Daltons with an anhydride-functionalized precursor poly(imide) having a weight average molecular weight of less than about 50,000 Daltons. The resultant poly(imide)s have weight average molecular weights greater than 50,000 Daltons, preferably greater than about 60,000 Daltons, more preferably greater than about 75,000 Daltons, even more preferably greater than about 100,000 Daltons, and most preferably greater than about 120,000 Daltons.
The functionalized precursor poly(imide)s as well as the high molecular weight poly (imide) are characterized by the presence of an imide group having the general formula —C (O)NRC(O)—. The imide group can be part of either an acyclic or cyclic system within the polymer. Preferred classes of precursor poly(imide)s are aromatic poly(imide)s, characterized by the presence of both an aromatic group and an imide group; poly(amidimide)s, characterized by the presence of both an imide group and an amide group (—C(O)NH—); and poly(etherimide)s, characterized by the presence of both an ether group and an imide group. Useful precursor poly(imide)s include those known in the art which are melt processable, such as those disclosed in U.S. Pat. Nos. 3,803,085 and 3,905,942.
Useful precursor polyimides have the general formula (I)
wherein V is a tetravalent linker without limitation, as long as the linker does not impede synthesis or use of the polyimide, and a is more than 1, typically from about 4 to about 1000 or more, and more preferably from about 4 to about 200. Suitable linkers include but are not limited to: (a) substituted or unsubstituted, saturated, unsaturated or aromatic monocyclic and polycyclic groups having about 5 to about 50 carbon atoms, (b) substituted or unsubstituted, linear or branched, saturated or unsaturated alkyl groups having 1 to about 30 carbon atoms; or combinations thereof. Suitable substitutions and/or linkers include, but are not limited to, ethers, epoxides, amides, esters, and combinations thereof. Preferred linkers include but are not limited to tetravalent aromatic radicals of formula (II), such as
wherein W is a divalent moiety selected from the group consisting of —O—, —S—, —C(O)—, —SO
2
—, C
y
H
2y
— (y being an integer from 1 to 5), and halogenated derivatives thereof, including perfluoroalkylene groups, or a group of the formula —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′ positions, and wherein Z includes, but is not limited, to divalent radicals of formula (III).
R in formula (I) includes but is not limited to substituted or unsubstituted divalent organic radicals such as: (a) aromatic hydrocarbon radicals having about 2 to about 20 carbon atoms and halogenated derivatives thereof; (b) straight or branched chain alkylene radicals having about 2 to about 20 carbon atoms; (c) cycloalkylene radicals having about 3 to about 20 carbon atoms, or (d) divalent radicals of the general formula (IV)
wherein Q includes but is not limited to divalent a divalent moiety selected from the group consisting of —O—, —S—, —C(O)—, —SO
2
—, C
y
H
2y
— (y being an integer from 1 to 5), and halogenated derivatives thereof, including perfluoroalkylene groups.
Preferred poly(etherimide) precursors resins comprise more than 1, typically about 4 to about 85 or more, and more preferably about 4 to about 75 structural units, of the formula (V)
wherein T is —O— or a group of the formula —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′ positions, and wherein Z includes, but is not limited, to divalent radicals of formula (III) as defined above.
In one embodiment, the polyetherimide may be a copolymer which, in addition to the etherimide units described above, further contains polyimide structural units of the formula (VI)
wherein R is as previously defined for formula (I) and M includes, but is not limited to, radicals of formula (VII).
The polyetherimide can be prepared by any of the methods well known to those skilled in the art, including the reaction of an aromatic bis(ether anhydride) of the formula (VIII)
with an organic diamine of the formula (IX) H
2
N—R—NH
2
wherein T and R are defined as described above in formulas (I) and (IV).
Examples of specific aromatic bis(ether anhydride)s and organic diamines are disclosed, for example, in U.S. Pat. Nos. 3,972,902 and 4,455,410. Illustrative examples of aromatic bis(ether anhydride)s of formula (VII) include: 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl] propane dianhydride; 4,4′-bis(3,4-dicarboxyphenoxy)diphenyl ether dianhydride
General Electric Company
Hampton-Hightower P.
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