Stock material or miscellaneous articles – Composite – Of polyester
Reexamination Certificate
2001-07-16
2002-08-20
Acquah, Samuel A. (Department: 1711)
Stock material or miscellaneous articles
Composite
Of polyester
C525S437000, C525S439000, C525S440030, C525S444000, C525S445000, C525S446000, C525S450000, C524S783000, C524S784000
Reexamination Certificate
active
06436549
ABSTRACT:
TECHNICAL FIELD
This invention generally relates to thermoplastics and articles formed therefrom. More particularly, the invention relates to block copolymers and their preparation from macrocyclic oligoesters and dihydroxyl-functionalized polymers.
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 are precursors to linear polyesters. Macrocyclic oligoesters exhibit low melt viscosity, which can be advantageous in some applications. 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.
Block copolymers such as copolyester elastomers are known that are typically prepared from short-chain aliphatic diols, aromatic diacids, and polyalkylene ether diols. For example, one commercial product is a copolymer of 1,4-butanediol, dimethyl terephthalate, and polytetramethylene ether glycol. This copolymer is prepared via polycondensation reactions in two steps at high temperature and high vacuum. The polycondensation reactions may take tens of hours or even days. In addition, the high temperature (about 250° C.) that is necessary for the polycondensation reactions causes significant degradation of polytetramethylene ether glycol. Furthermore, the molecular weight of polytetramethylene ether glycol is limited to 1000 or less in order to minimize significant phase separation during the polycondensation reaction.
SUMMARY OF THE INVENTION
Block copolymers of high molecular weight have been prepared from macrocyclic oligoesters and dihydroxyl-functionalized polymers at an elevated temperature in the presence of a transesterification catalyst. The methods of the invention allow the design and control of the elasticity, the crystallinity, the ductility, and the molecular weight of the resulting block copolymers, while retaining other desirable properties of polyesters prepared from macrocyclic oligoesters as precursors.
In one aspect, the invention generally features a method for making a block copolymer. In one embodiment, the method includes the step of contacting a macrocyclic oligoester and a dihydroxyl-functionalized polymer at an elevated temperature in the presence of a transesterification catalyst. The co-polymerization produces a block copolymer of polyester (derived from the macrocyclic oligoester) and the dihydroxyl-functionalized polymer. The macrocyclic oligoester has a structural repeat unit of formula (I):
wherein R is an alkylene, a cycloalkylene, or a mono- or polyoxyalkylene group; and A is a divalent aromatic or alicyclic group.
In another aspect, the invention features a method for making high molecular weight block copolymer. In one embodiment, the method includes the steps of: (a) contacting a macrocyclic oligoester and a dihydroxyl-functionalized polymer at an elevated temperature in the presence of a transesterification catalyst to produce a block copolymer of polyester and the dihydroxyl-functionalized polymer; and (b) heating the block copolymer in the presence of a chain extension agent. The chain extension step results in a higher molecular weight block copolymer of polyester and the dihydroxyl-functionalized polymer.
In yet another aspect, the invention features another method for making high molecular weight block copolymer. In one embodiment, the method includes the steps of (a) heating a dihydroxyl-functionalized polymer with a diester in the presence of a transesterification catalyst, thereby producing a chain-extended dihydroxyl-functionalized polymer; and (b) contacting the chain-extended dihydroxyl-functionalized polymer with a macrocyclic oligoester at an elevated temperature in the presence of a transesterification catalyst. The co-polymerization produces a block copolymer of polyester and the chain-extended dihydroxyl-functionalized polymer.
In yet another aspect, the invention generally features a method for extending the chain length of a polyester polymer. In one embodiment, the method includes the step of contacting the polyester polymer and a chain extension agent at an elevated temperature.
In yet another aspect, the invention features a block copolymer. The block copolymer has at least two block units. The first block unit has, within its polymeric backbone, at least one first structural unit of formula (II)
where R is an alkylene, or a cycloalkylene or a mono- or polyoxyalkylene group, and A is a divalent aromatic or alicyclic group. The second block unit has, within its polymeric backbone, at least one second structural unit of formula (III)
—B— (III)
where B is an alkylene, or a cycloalkylene or a mono- or polyoxyalkylene group. One or more of the carbon atoms in B may be replaced with an oxygen atom, a nitrogen atom, or a sulfur atom.
The foregoing and other objects, aspects, features, and advantages of the invention will become more apparent from the following description and claims.
DESCRIPTION
In an embodiment according to the present invention, high molecular weight block copolymers can be prepared from macrocyclic oligoesters and dihydroxyl-functionalized polymers at an elevated temperature 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 “dihydroxyl-functionalized polymer” means a polymer having at least two hydroxyl functional groups. Typically, the at least two hydroxyl functional groups are at the ends of a polymer chain. However, the polymer may be branched and each of the two or more of branches of the polymer chain may have a hydroxyl functionalized end.
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
Acquah Samuel A.
Cyclics Corporation
Testa Hurwitz & Thibeault LLP
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