Stock material or miscellaneous articles – Composite – Of polyester
Reexamination Certificate
2001-06-05
2002-07-16
Acquah, Samuel A. (Department: 1711)
Stock material or miscellaneous articles
Composite
Of polyester
C528S354000, C528S357000, C528S359000, C525S437000
Reexamination Certificate
active
06420048
ABSTRACT:
TECHNICAL FIELD
This invention generally relates to thermoplastics and articles formed therefrom. More particularly, the invention relates to high molecular weight copolyesters and their preparation from macrocyclic oligoesters and cyclic esters.
BACKGROUND INFORMATION
Linear polyesters such as poly(alkylene terephthalate) are generally known and commercially available where the alkylene typically has 2 to 8 carbon atoms. Linear polyesters have many valuable characteristics including strength, toughness, high gloss and solvent resistance. Linear polyesters are conventionally prepared by the reaction of a diol with a dicarboxylic acid or its functional derivative, typically a diacid halide or ester. Linear polyesters may be fabricated into articles of manufacture by a number of known techniques including extrusion, compression molding, and injection molding.
Recently, macrocyclic oligoesters were developed which have unique properties. These properties make them attractive as matrices for engineering thermoplastic composites. The desirable properties stem from the fact that macrocyclic oligoesters exhibit low melt viscosity, allowing them easily to impregnate a dense fibrous preform followed by polymerization to polyesters. Furthermore, certain macrocyclic oligoesters melt and polymerize at temperatures well below the melting point of the resulting polymer. Upon melting and in the presence of an appropriate catalyst, polymerization and crystallization can occur virtually isothermally.
Despite the above-described properties and other advantages, some of the resulting polyesters prepared from macrocyclic oligoesters typically display an increase in crystallinity that invariably diminishes the favorable properties including the polymer's ductility. Thus, methods are needed for preparing polyesters with favorable cystallinity and ductility while retaining the advantages of using macrocyclic oligoesters as precursors to polyesters.
SUMMARY OF THE INVENTION
Copolyesters of high molecular weight have been prepared from macrocyclic oligoesters and cyclic esters in the presence of a transesterification catalyst. The copolyesters so prepared show favorable crystallinity and ductility while retaining other desirable properties of polyesters prepared from macrocyclic oligoesters as precursors.
In one aspect, the invention generally features a method of making a copolyester. In one embodiment, the method includes the steps of providing a macrocyclic oligoester, providing a cyclic ester other than a macrocyclic oligoester, and contacting the macrocyclic oligoester and the cyclic ester in the presence of a transesterification catalyst at an elevated temperature to produce a copolyester. The macrocyclic oligoester has a structural repeat unit of formula (I):
wherein A is an alkylene, a cycloalkylene, or a mono- or polyoxyalkylene group; and B is a divalent aromatic or alicyclic group.
In another aspect, the invention generally features a method of making a block copolymer of polyesters. In one embodiment, the method includes contacting a macrocyclic oligoester and a transesterification catalyst at an elevated temperature to form a first polymeric segment. Subsequently contacting the first polymeric segment, a cyclic ester that is not a macrocyclic oligoester, and the transesterification catalyst at an elevated temperature forms a second polymeric segment. The above steps then are sequentially repeated a desired number of times to form a block copolyester having additional first and second polymeric segments.
In another embodiment that is a variation of the above method of making a block copolymer, a first polymeric segment is formed by contacting a cyclic ester that is not a macrocyclic oligoester and a transesterification catalyst at an elevated temperature. Subsequently contacting this first polymeric segment, a macrocyclic oligoester, and the transesterification catalyst at an elevated temperature forms a second polymeric segment. The above steps then are sequentially repeated a desired number of times to form a block copolymer having additional first and second polymeric segments.
In yet another aspect, the invention features a composition that is a copolyester. In one embodiment, the copolyester contains, within its polymeric backbone, at least one structural unit of formula (I) (as defined above) and at least one structural unit of formula (II)
—R
1
—O—C(O)—R
2
(II)
wherein R
1
and R
2
are independently an organic moiety with the proviso that R
1
is not —O—A′— if R
2
is —B′—C(O)—. A′ is an alkylene, a cycloalkylene, or a mono- or polyoxyalkylene group. B′ is a divalent aromatic or alicyclic group.
In yet another aspect, the invention features a block copolymer of polyesters. A first block unit of the copolymer has, within its polymeric backbone, at least one first structural unit of formula (I), as defined above. A second block unit has, within its polymeric backbone, at least one second structural unit of formula (II), as defined above.
The foregoing and other objects, aspects, features, and advantages of the invention will become more apparent from the following description and claims.
DESCRIPTION
The present invention is related to the surprising discovery that high molecular weight copolyesters having favorable crystallinity and ductility can be prepared from macrocyclic oligoesters and cyclic esters in the presence of a transesterification catalyst.
Definitions
The following general definitions may be helpful in understanding the various terms and expressions used in this specification.
As used herein, a “macrocyclic” molecule means a cyclic molecule having at least one ring within its molecular structure that contains 8 or more atoms covalently connected to form the ring.
As used herein, an “oligomer” means a molecule that contains 2 or more identifiable structural repeat units of the same or different formula.
As used herein, an “oligoester” means a molecule that contains 2 or more identifiable ester functional repeat units of the same or different formula.
As used herein, a “macrocyclic oligoester” means a macrocyclic oligomer containing 2 or more identifiable ester functional repeat units of the same or different formula. A macrocyclic oligoester typically refers to multiple molecules of one specific formula having varying ring sizes. However, a macrocyclic oligoester may also include multiple molecules of different formulae having varying numbers of the same or different structural repeat units. A macrocyclic oligoester may be a co-oligoester or multi-oligoester, i.e., an oligoester having two or more different structural repeat units having an ester functionality within one cyclic molecule.
As used herein, a “cyclic ester” means a cyclic molecule having at least one ring within its molecular structure that contains an ester functionality within the ring. A cyclic ester typically refers to multiple molecules of one specific cyclic ester. A cyclic ester as used herein is not a macrocyclic oligoester as defined above.
As used herein, “an alkylene group” means —C
n
H
2n
—, where n≧2.
As used herein, “a cycloalkylene group” means a cyclic alkylene group, —C
n
H
2n-x-
, where x represents the number of H's replaced by cyclization(s).
As used herein, “a mono- or polyoxyalkylene group” means [—(CH
2
)
m
—O—]
n
—(CH
2
)
m
—, wherein m is an integer greater than 1 and n is an integer greater than 0.
As used herein, “a divalent aromatic group” means an aromatic group with links to other parts of the macrocyclic molecule. For example, a divalent aromatic group may include a meta- or para-linked monocyclic aromatic group (e.g., benzene).
As used herein, “an alicyclic group” means a non-aromatic hydrocarbon group containing a cyclic structure therein.
As used herein, a “block copolymer” means a copolymer having segments of two or more polymers linked to one another. A block copolymer has constitutionally different structural units. Adjacent segments (i.e., blocks) contain structural units derived from different characteristic
Acquah Samuel A.
Cyclics Corporation
Testa Hurwitz & Thibeault LLP
LandOfFree
High molecular weight copolyesters from macrocyclic... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with High molecular weight copolyesters from macrocyclic..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and High molecular weight copolyesters from macrocyclic... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2879071